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The preservation of Milankovitch cycles in the stratigraphic record provides independent geological information to study our ancient solar system and can be leveraged to constrain existing theoretical models. Here, we identify 34 high-quality cyclostratigraphic records spanning the past 650 million years and use them to infer the evolution of the Earth-Moon system through a Bayesian inversion method. We reconstruct the time evolution of Earth's axial precession frequency, lunar distance, length of day, and the periods of obliquity and climatic precession cycles. The results indicate an interval of high tidal energy dissipation in the Earth-Moon system at ~300 to 200 million years ago, and are broadly consistent with an independently calculated tidal evolution model. Our results provide an improved determination of the past periods of obliquity and climatic precession for astrochronology applications and yield important constraints on the history of tidal energy dissipation during the Phanerozoic Eon. [ABSTRACT FROM AUTHOR]

East Asia experienced complex climatic changes during the Eocene. Due to the lack of a high‐precision time framework covering the Eocene, the characteristics of sedimentary and climate evolution in this period remain unclear. The Jianghan Basin (Central China) developed an Eocene continental succession, which is composed of lower red beds and upper salt‐lake deposits exhibiting clear sedimentary rhythms, making these strata an ideal target for astronomical cycle analysis. Based on the established floating astronomical timescale, the lower red beds in the basin formed during the early–middle Eocene and were dominated by eccentricity cycles. The upper salt‐lake deposits formed during the middle–late Eocene and recorded obliquity cycles. The change in facies indicates that the climate transitioned from continuously arid to less arid with periodic relative wetness, which was forced by orbital cycles. Significant obliquity signals recorded by salt rhythmites responded to Eocene global temperature changes and Tibetan region uplift, which can be important markers of a monsoon‐like climate. Comparing the sedimentary and climatic characteristics of other Eocene lake basins in East Asia, the extension of the Eocene East Asian monsoon may have initiated during ca 43.6 to 40.0 Ma. This study provides a new perspective for understanding the early evolution of the East Asian monsoon. [ABSTRACT FROM AUTHOR]

Numerical forward modelling and laboratory experiments suggest that autogenic factors in the sediment routing system serve as long‐pass filters, preserving only orbital cycles with a period exceeding the compensation timescale, Tc, or thickness in the depth domain exceeding the compensation depth scale, Hc. For a specific orbital cycle with a certain period, this preservation in alluvial strata occurs unless it exhibits a sufficiently large amplitude. This study stratigraphically confirms, for the first time, the long‐pass filtering of autogenic dynamics using elemental data from the alluvial–lacustrine Sifangtai and Mingshui formations in the Songliao Basin. Spectral analysis of the Si and Zr series in coarse‐grained sediments reveals no cyclic signal with thicknesses below the estimated lower limits of Hc. This implies that the spatial storage threshold for orbital cycles in proxies of the coarse‐grained sediment component is equal to or less than Hc. However, cyclic signals of obliquity and precession with smaller thicknesses are identified in Ti, Fe and Al enriched in the fine‐grained sediment components of the stratigraphy. Notably, previously reported proxies preserving high‐frequency orbital cycles are derived from fine‐grained sediment components, differing from the sedimentation rate series used in the reported experimental studies. Therefore, the authors hypothesize a grain‐size component‐dependent storage threshold, suggesting that the storage threshold of orbital cycles in proxies associated with fine‐grained components is lower. This hypothesis arises from the weaker effect of autogenic dynamics on the content of fine‐grained sediment components transported to the sampling site by a suspended load compared to coarser components that are subjected to stronger autogenic dynamics within or near channels. The hypothesis and model presented propose a dynamic process elucidating the nuanced roles of autogenic dynamics in preserving orbital cycles. This perspective, considering sediment composition, inspires prioritizing proxies enriched in the fine‐grained fraction for identifying allogenic cycles in alluvial strata. [ABSTRACT FROM AUTHOR]

Cyclostratigraphy is an important observational window into the history of the Earth-Moon system. However, there is limited information from the Mesoproterozoic era (1.0 to 1.6 billion years ago); accordingly, only weak constraints on Earth-Moon separation and tidal dissipation are available for this time. To close this knowledge gap, we analyze cyclostratigraphy from the Yemahe Formation (~1.2 billion years ago), Wumishan Formation (~1.5 billion years ago), and Chuanlinggou Formation (~1.6 billion years ago) in China. We use a Bayesian inversion method to analyze the three cyclostratigraphic sections. We combine previous results with these three estimates to construct an updated Earth-Moon system evolution and tidal dissipation history after 2.5 billion years ago. The results show a tidal dissipation peak that is consistent with the model predictions within the error range but also that there may be an additional resonance fluctuation in the Mesoproterozoic era. [ABSTRACT FROM AUTHOR]

Alluvial stratigraphy builds up over geologic time under the complex interplay of external climatic and tectonic forces and internal stochastic processes. This complexity makes it challenging to attribute alluvial stratigraphic changes to specific factors. Geological records indicate pronounced and persistent climatic changes during the Phanerozoic, while the effects of these changes on alluvial stratigraphy remain insufficiently documented. We provide evidence for 405 k.y. long-eccentricity climate forcing of alluvial stratigraphy in the lower Eocene Willwood Formation of the Bighorn Basin, Wyoming (USA). Two ∼90-m-thick intervals, characterized by a relative paucity of sand, dominance of sinuous-river channels, and floodplain sediments with better-developed paleosols, coincide with eccentricity maxima as determined through integrated stratigraphic methods. These intervals are interspersed with three contrasting intervals, marked by relatively high sand content, prevalent braided-river channels, and less-developed paleosols, corresponding to eccentricity minima. A comprehensive genetic model that integrates climate, source-to-sink system, and alluvial dynamics to explain these findings remains to be elucidated. Given the consistent presence of the 405 k.y. eccentricity cycle throughout Earth’s history, it is plausible to infer that its influence may be discernible across a wide array of alluvial stratigraphic records. [ABSTRACT FROM AUTHOR]

The rhythmic evaporation cycle is an ideal recorder of astronomical cycle signals, but studies on cyclostratigraphy have yet to be directly conducted on halite-rich strata. The Qianjiang Depression of the Jianghan Basin is a representative Eocene East Asian halite-rich basin, and the salt rhythmites that developed therein are important recorders of climate evolution in East Asia. This study selected five wells for basin-scale cyclostratigraphy analysis, taking the Lower Qian 4 member of the Qianjiang Formation as the research object. This study found that the basinal salt lake facies were dominated by obliquity cycles, whereas the shallow-water deposits mainly recorded short eccentricity cycles. The study also found that s3-s6 obliquity cycles could be detected throughout the salt lake sedimentary record. Therefore, a stepwise astronomical tuning scheme was adopted. First, the target intervals in different sedimentary areas were preliminarily tuned to s3-s6 obliquity cycles, and stratigraphic correlation was performed. Then, the tuned data were further adjusted using obliquity cycles to reveal the impact of obliquity on the development of salt rhythmites and establish a floating astronomical time scale (ATS). Sedimentary noise models and pollen analysis further demonstrated that obliquity amplitude modulation cycles drove periodic changes in hydrology and climate. Based on the spatiotemporal distribution of salt rhyth-mite-rich strata in Paleogene East Asia, this study proposes that the development of rhythmic evaporites can reveal the existence of a monsoon-like climate. Astronomical influence was an important driving force for developing the middle Eocene East Asian monsoon. [ABSTRACT FROM AUTHOR]

The coal‐bearing series of the Eocene Pinghu Formation is one of the focused reservoir exploration in the Xihu Sag. This study conducted a cyclostratigraphy time series analysis using natural gamma‐ray (GR) logging data from four boreholes of the Xihu Sag. The spectral analysis shows a good match with the La2004 orbital solution. The sedimentation duration calculated by the astronomical age models spans at least 4.31–5.94 Myr, with an average sedimentation rate of 13.47–18.57 cm/kyr. The Pinghu Formation is subdivided into 1 second‐order, 3 third‐order and 14 fourth‐order sequences within seismic, well logging and 405 kyr‐long cycles constraints. Based on available age‐control data, the Pinghu Formation is corresponding to the middle‐late Eocene. The floating astronomical timescale of XH‐3 borehole now provides a new age constraint for the Pinghu Formation. There are four shorter‐term (<2 Myr) regional sea‐level cycles in the Pinghu Formation, which are similar to the calibrated global sea‐level fluctuations. Inconsistencies between reconstructed sea‐level curve by sedimentary noise modelling and true sea level inferred from lithology and sequence reveal various sources of noise in the sedimentary record. Variations in the distribution and thickness of coal seams in the Pinghu Formation appear to be a stratigraphic response to astronomical and non‐astronomical forcing such as regional tectonicssm and facies changes. [ABSTRACT FROM AUTHOR]

Astronomical (or Milanković) forcing of the Earth system is key to understanding rhythmic climate change on time scales ≳104 y. Paleoceanographic and paleoclimatological applications concerned with past astronomical forcing rely on astronomical calculations (solutions), which represent the backbone of cyclostratigraphy and astrochronology. Here we present state‐of‐the‐art astronomical solutions over the past 3.5 Gyr. Our goal is to provide tuning targets and templates for interpreting deep‐time cyclostratigraphic records and designing external forcing functions in climate models. Our approach yields internally consistent orbital and precession‐tilt solutions, including fundamental solar system frequencies, orbital eccentricity and inclination, lunar distance, luni‐solar precession rate, Earth's obliquity, and climatic precession. Contrary to expectations, we find that the long eccentricity cycle (LEC) (previously assumed stable and labeled "metronome," recent period ∼405 kyr), can become unstable on long time scales. Our results reveal episodes during which the LEC is very weak or absent and Earth's orbital eccentricity and climate‐forcing spectrum are unrecognizable compared to the recent past. For the ratio of eccentricity‐to‐inclination amplitude modulation (recent individual periods of ~2.4 and ~1.2 Myr, frequently observable in paleorecords) we find a wide distribution around the recent 2:1 ratio, that is, the system is not restricted to a 2:1 or 1:1 resonance state. Our computations show that Earth's obliquity was lower and its amplitude (variation around the mean) significantly reduced in the past. We therefore predict weaker climate forcing at obliquity frequencies in deep time and a trend toward reduced obliquity power with age in stratigraphic records. For deep‐time stratigraphic and modeling applications, the orbital parameters of our 3.5‐Gyr integrations are made available at 400‐year resolution. Key Points: We provide orbital eccentricity, inclination, oliquity, and climatic precession for use in paleostudies/climate models over the past 3.5 GyrThe long eccentricity cycle (previously used as "metronome") can become unstable on long time scalesEarth's past obliquity forcing/amplitude was significantly reduced. We predict reduced obliquity power with age in stratigraphic records [ABSTRACT FROM AUTHOR]

According to Milankovitch's theory, periodic climate change in Earth's history is controlled by the periodic changes in the Earth's orbit and axis of rotation. Milankovitch cycle include eccentricity, obliquity, and precession cycles. In addition to them, there are also some amplitude modulation (AM) cycles that affect the climate system through a series of "nonlinear" feedback processes, such as the 173 kyr obliquity AM cycle. Previous studies have demonstrated that the -170 kyr cycle modulate the paleoclimate and carbon cycle at mid- high latitude regions in the Meso-Cenozoic. However, due to the limitation of astronomical solutions and the lack of high-resolution geological records, the -170 kyr cycle has been less reported in the Paleozoic Era. In this study, cyclostratigraphic analysis of natural gamma ray (GR) logging data from four wells (Ji30, Ji31, Ji32, and Ji174) and total organic carbon (TOC) data from well Ji174 penetrating the Early Permian Lucaogou Formation in Jimusar Sag, Junggar Basin suggests preservation of eccentricity, obliquity, and precession cycles, and the -170 kyr AM cycle. Through the astronomical tuning of GR logging data obtained from four wells to eccentricity target cycles, we established the floating astronomical time scale (ATS). The results indicate an average sedimentation rate ranging from 7.4 to 9.5 cm/kyr and a duration from 2.8 to 3.2 million years (Myr) for the Lucaogou Formation. The differences in sedimentation rate and duration among these four wells may result from different well locations. Moreover, the -170 kyr cycle signal has been identified in the detrended GR logging and TOC data series, and its obliquity AM series. This signal might be attributed to the obliquity AM cycles originated from the interaction between s3 and s6 (s3 and s6 represent the precession of nodes of Earth and Saturn), which was recorded in the GR logging and TOC data time series due to nonlinear responses within the depositional system. [ABSTRACT FROM AUTHOR]

The Late Albian- Early Turonian Formation is the second-largest carbonate reservoir in the South and Southwest of Iran hosting significant accumulations of hydrocarbons deposited on the edge of the Neotethys. The purpose of this study is to analyze the sequence stratigraphy and Milankovitch cycles of the Sarvak Formation in three wells of the Anaran exploration block by using the Maximum Entropy Spectral Analysis (MESA) of gamma ray logs and integration with core studies to achieve a comprehensive understanding of the formation. The study of 353 microscopic samples led to the identification of 8 microfacies including (a) mudstone to oligostigenid wackestone with benthic and pelagic foraminifera, (b) packstone-rudstone, (c) rudistic with benthic foraminifers, (d) bioclast intraclast, (e) grainstone with benthic foraminifers, (f) peloid Wackestone to peloid wackestone with low benthic foraminifera diversity, (g) Peloid packstone with diverse benthic Foraminifers and (h) Bioclast Wackestone, which are distributed in three facies belts ranging from lagoon to shoal and open marine settings. In addition to four third-order sedimentary sequences were also identified based on facies changes combined with the Prediction Error Filter Analysis (PEFA), Integrated Prediction Error Filter Analysis (INPEFA) diagrams. Examining the Milankovitch cycles based on the analysis of the distances between gamma peaks and MESA revealed 100 thousand year cycles. Orbital dating according to the counting of the Milankovitch cycles indicates the equivalent age of 11 to 12 million years for the Sarvak Formation. [ABSTRACT FROM AUTHOR]

Repeated carbon isotope excursions and widespread organic-rich shale deposition mark the Middle and Upper Devonian series. Various explanations such as extensive volcanism and land plant evolution have been given for these perturbations and the general sensitivity of the Devonian oceans to the development of anoxia, but their repeated nature suggests that astronomical forcing may have controlled their timing. Here, a cyclostratigraphic study of the Kellwasser Crisis at the Frasnian–Famennian stage boundary (ca. 372 Ma) is carried out. The Kellwasser Crisis was one of the most ecologically impactful of the Devonian perturbations and is ranked among the "Big Five" Phanerozoic mass extinctions. The studied site is the Winsenberg roadcut section in the Rhenish Massif, Germany, which represents a quiet tropical shelf basin setting. Centimetre-scale elemental records, generated by portable X-ray scanning, allow for testing of the hypothesis that a 2.4 Myr eccentricity node preceded the Upper Kellwasser event. The study's results are supportive of this hypothesis. We find enhanced chemical weathering (K 2 O / Al 2 O 3) during the period leading up to the Upper Kellwasser and a peak in distal detrital input (SiO 2 / CaO) and riverine runoff (TiO 2 / Al 2 O 3) just prior to the start of the Upper Kellwasser event. We interpret this pattern as the long-term eccentricity minimum facilitating excessive regolith build-up in the absence of strong seasonal contrasts. The Earth's system coming out of this node would have rapidly intensified the hydrological cycle, causing these nutrient-rich regoliths to be eroded and washed away to the oceans, where they resulted in eutrophication and anoxia. An astronomical control on regional climate is observed beyond this single crisis. Wet–dry cycles were paced by 405 kyr eccentricity, with both the Lower and Upper Kellwasser events taking place during comparatively drier times. A precession-sensitive monsoonal climate system prevailed on shorter timescales. Intensification of this monsoonal system following the node may have caused the widespread regolith erosion. We estimate the total duration of the Kellwasser Crisis at ca. 900 kyr, with the individual events lasting for ca. 250 and 100 kyr, respectively. If astronomical control indeed operated via regolith development in monsoonal climates, then land plants may have played an important role. This would not have been through evolutionary steps directly triggering Kellwasser perturbations but by gradually strengthening the climatic response to orbital forcing via soil development – creating soils thick enough to meaningfully respond to orbital forcing – and intensifying the hydrological cycle. [ABSTRACT FROM AUTHOR]

The Early Eocene Climatic Optimum (EECO) may be a potentially useful analog for future global warming under high CO2 concentrations. However, a paucity of orbital‐scale terrestrial records limits our understanding of how the hydrological cycle responded during this protracted (∼4 Myr) interval of global warmth. In this study, we combine zircon U‐Pb dating and cyclostratigraphy to establish a high‐resolution astronomical timescale spanning the EECO (∼52.9 Ma to ∼49.9 Ma) through a >1 km fluviolacustrine succession from the Gonjo Basin, Southeast Tibet. Our results suggest that hydroclimate variability in the region during this interval was strongly controlled by eccentricity forcing (∼405 Kyr, ∼135–100 Kyr, and possibly ∼200 Kyr cycles). The dominance of eccentricity forcing in our record is consistent with coeval marine records, and indicates that modulation of low‐latitude summer insolation through nonlinear interactions with the global carbon cycle likely controlled hydroclimate and paleolake level in the Gonjo basin during the EECO. Our study offers new perspectives for the forcing mechanisms of terrestrial hydroclimate changes of East Asia in response to subtle changes in insolation during the EECO. Plain Language Summary: High resolution and relatively long‐duration terrestrial paleoenvironmental records across an interval of extreme warmth ∼50 million years ago (called the EECO) are rare, limiting our understanding of how the hydrological cycle operated during this time interval. In this study, we present high‐resolution geochemical data through a succession of continental sedimentary rocks from the Gonjo Basin (Southeast Tibet) spanning the EECO. Our data suggest that EECO hydroclimate was dominated by climate forcing controlled by variations in Earth's eccentricity, emphasizing the importance of eccentricity modulation of low‐latitude summer insolation through nonlinear interactions with the global carbon cycle. This finding is consistent with coeval marine records. Our study provides new insights into the forcing mechanisms of terrestrial paleoclimate change in East Asia under warm climate conditions and high CO2. Key Points: Astronomical timescale spanning the Early Eocene Climatic Optimum (EECO) established in East Asia terrestrial recordRelatively wetter and warmer climate during ∼52.9–52.39 Ma and ∼50.34–49.9 MaEccentricity forcing of EECO terrestrial climate, consistent with coeval marine records [ABSTRACT FROM AUTHOR]

The Hirnantian period, making the end of the Ordovician with significant mass extinctions and large ice‐sheets, is a critical interval for studying paleoclimate variations. This research represents the first cyclostratigraphic study of this period, utilizing high‐resolution (1 mm sampling rate) geochemical data from the ∼7‐m thick SH‐1 drill core, capturing the latest Ordovician glaciation. Our analysis identifies the presence of Milankovitch cycles with periods of 17–21, ∼33, and ∼100‐kyr, suggesting an optimal sedimentation rate of 3.1 m/Myr. Notably, we detected signals of millennial‐scale variability, aligning with the ∼1.5‐kyr Dansgaard‐Oeschger and ∼2.4‐kyr Hallstatt heliomagnetic cycles, even in deposits lacking visible laminae alternation. This finding bolsters the hypothesis of an external origin for these millennial‐scale features. Additionally, our reconstruction of sea‐level variations, using principal component analysis and sedimentary noise modeling, reveals two intervals of sea‐level fall and one sea‐level rise, linked to an astronomical forcing cycle of ∼1.2‐Myr. The obliquity band power‐total power ratios correspond to ∼1.2‐Myr periodicities for s4‐s3 term. The synchronization of ∼1.2‐Myr cycle minimum with a sea‐level drop (low PC1 value) suggests that glacio‐eustatic variations were influenced by ∼1.2‐Myr obliquity modulation cycles. This research enhances our understanding of glacio‐eustasy during the latest Ordovician from an astronomical perspective, offering valuable insights into the interplay between orbital cycles and Earth's paleoclimate. Key Points: Millennial‐scale cycles have been detected based on five high‐resolution proxy seriesMillennial‐scale cycle preserved in the Hirnantian was linked to the D‐O and Hallstatt cycle∼1.2‐Myr PC1 filter revealed one rise and two falls of sea‐level during Hirnantian [ABSTRACT FROM AUTHOR]

There are few documentations of far‐field effects of coolhouse glaciation and its signature preserved within Middle Jurassic carbonate platforms. Through outcrop logging and time series analysis we document the cyclostratigraphy of the upper Bajocian‐Bathonian interval of the Adriatic Platform, Croatia. The 200 m thick, ∼3.3 Myr duration cyclic platform record consists of peritidal carbonate parasequences (n = 109) with high‐energy grainstone‐rudstone bases fining up into micritic carbonate caps. There is little evidence of long‐term exposure near purported sequence boundaries, indicating the succession is conformable above the parasequence scale. Time series were constructed using Dunham rank and stratigraphic position, and parasequence thickness and stratigraphic position. A statistical estimation of accumulation rates using average spectral misfit (ASM) and correlation coefficient (COCO) methods that compare spectral peaks with an astronomical model at various sedimentation rates suggests that these rates ranged from 4.5 to 6 cm/kyr, which is compatible with long‐term rates based on thickness divided by duration. The time series analysis of rank series and cycle thickness series indicates long‐term obliquity modulation (∼1 Myr), short obliquity modulation (173 kyr), strong obliquity, and weak precession. The 173 kyr cycle is particularly evident in the cycle thickness series. The similarity of the spectra to the obliquity‐dominated Cenozoic coolhouse supports moderate southern hemisphere glaciation driving glacioeustatic sea level changes during the Middle Jurassic. Plain Language Summary: Earth's climate has been paced by eccentricity of its orbit (periods of 405,000 and 100,000 years) which modulates precession (or wobble, ∼20,000 years), and the tilt (obliquity) of its axis (∼40,000 years), with tilt and wobble being slightly shorter as we go back in time. We examined the succession of carbonate rocks in a 166–169.5 million‐year‐old, Middle Jurassic carbonate platform in Croatia, deposited during a time when there is evidence of moderate glaciation at the poles. The results indicate that the rock record was dominated by the tilt signal with little evidence of eccentricity. This is very similar to the deep sea record from 2 million to 700,000 years ago, which also is dominated by obliquity associated with moderate glaciation at both poles. The results strongly support the contention of moderate glaciation during the Middle Jurassic. Key Points: Middle Jurassic Bajocian‐Bathonian dominated by obliquity forcing of climate/sea levelOrbital signal is dominated by ∼1 Myr long obliquity cycle, short (173 kyr) obliquity modulation cycle, obliquity, and minor precessionObliquity forcing supports the existence of moderate ice sheets at high latitudes in the Middle Jurassic [ABSTRACT FROM AUTHOR]

The Paleoproterozoic was an important stage in the evolution of life and the environment during Earth's history. Understanding astronomical rhythms and solar system behavior in the Paleoproterozoic is often challenging. In this study, ∼190 m high‐resolution magnetic susceptibility (MS) and ∼30 m high‐resolution Ba/Al data are used to conduct cyclostratigraphic analyses of the Chuanlinggou Formation in the Yanliao Rift, North China Craton. Spectral analysis indicates significant peaks at wavelengths of 12.1–7.7, 2.8–1.6, 0.58–0.33, and 0.29–0.22 m, which matches well with the astronomical cycles predicted by Waltham for ∼1,640 Ma. A 9.9‐Myr astronomical time scale is constructed by tuning the MS series to the 405‐kyr‐long eccentricity cycle. The geological records show ∼1.56‐Myr very long eccentricity period and ∼1.0‐Myr very long obliquity period (close to 3(s4 − s3) − 2(g4 − g3) = 0) in the Paleoproterozoic. The sea‐level change curve predicted by dynamic noise models reveals a significant ∼1.0‐Myr period, indicating that sea level fluctuation may have been driven by the very long obliquity period. Bayesian inversion is used to further estimate the evolution of the ancient Earth‐Moon orbital parameters, constraining a precession rate of 87.14 ± 0.25 arcsec/year and an Earth‐Moon distance of 341,530 ± 390 km for the Paleoproterozoic Changcheng System. These results indicate that astronomical orbital forcing may have played an important role in climate and sea‐level changes in the Precambrian, increasing the understanding of the fundamentals of global sea level fluctuations, orbitally driven mechanisms and the chaotic behavior of the Precambrian solar system. Plain Language Summary: Orbital parameters and long‐term behavior have changed during geological history. For the first time, we found new resonance states between Mars and Earth (i.e., a very long eccentricity period of ∼1.56 Myr and a very long obliquity period of ∼1.0 Myr) from the geological records of the Paleoproterozoic Changcheng System in the Yanliao Rift of the North China Craton. The reconstructed sea‐level change curve shows a significant ∼1.0‐Myr period, indicating that sea level fluctuations may have been driven by the very long obliquity period in the Precambrian. The orbital parameters in the Paleoproterozoic are recovered using Ba/Al ratios, and the calculated precession constant is 87.14 ± 0.25 arcsec/year. The Earth‐Moon distance was 341,530 ± 390 km, and the length of day (LOD) was 18.06 ± 0.05 hr, which indicates that lunar recession may have been slower in deep time. These results increase the understanding of astronomical rhythms and the chaotic behavior of the solar system in the Precambrian. Key Points: A new Earth‐Mars resonance state (3(s4 − s3) − 2(g4 − g3) = 0) is revealed from the Precambrian geological recordsThe ∼1.0‐Myr very long obliquity period significantly affected sea level fluctuations under the Mesoproterozoic greenhouse climate [ABSTRACT FROM AUTHOR]

Over the last 66 million years, Earth has undergone dramatic climate changes, shifting from a warm greenhouse to the more recent cold icehouse with polar ice caps in both hemispheres. Geological records show that the transition between these equilibrium states caused significant long‐term eustatic sea‐level and atmospheric CO2 decline paced by external orbital motions. Such eustatic variability influenced the stacking pattern of sedimentary successions, generating cyclic sequence boundaries that may be globally correlated. However, the impact of such oscillation along the Brazilian margin is largely unknown. This study used the natural gamma‐ray log from a well (ES‐2) at the offshore Espírito Santos Basin (western South Atlantic) measured between late‐Palaeocene and late‐Miocene. Null hypothesis tests ‐ evolutionary Average Spectral Misfit and Correlation Coefficient of no orbital modulation ‐ were executed to confirm the influence of astronomical parameters. The evolutionary Time Optimization algorithm was used to extract the sedimentation rate and depositional time. The anchored timescale shows a chronological interval placed between 58.97 and 7.72 ± 0.1 Ma (mid‐Thanetian – late Tortonian), mostly influenced by long‐eccentricity and short‐eccentricity (405 kyr and ca 100 kyr, respectively) and obliquity (ca 40 kyr) and their respective amplitude modulations (ca 2.4 Myr and 1.2 Myr). Applying the Integrated Prediction Error Filter Analysis and a high‐resolution age model, this study identified main depositional trends through time and correlated them to global sea‐level change. The correlation indicates that several intervals of global sea‐level reduction agree with a regressive trend at the ES‐2 site, but this relation is affected during enhanced regional tectonic activity intervals, as related to the emplacement of the Abrolhos Archipelago. The strategy adopted here is a way to join cyclostratigraphy and sequence stratigraphy, and promotes high‐resolution local‐to‐global correlation by identifying key stratigraphic surfaces. This will be relevant for palaeoclimatic studies and the geoscientific industry. [ABSTRACT FROM AUTHOR]

We present high‐resolution (every 2 cm) magnetic susceptibility (MS) data from the Sancerre‐Couy drill core (Paris Basin), spanning the latest Sinemurian to the earliest Aalenian (Early Jurassic). This record allows to build a 20‐million‐year cyclostratigraphic interval using the stable 405 kyr (g2–g5) orbital eccentricity cycle and to focus on long‐period cyclicities and their potential implications for the chaotic diffusion in the inner Solar System and sea‐level changes. Time series analysis indicates evidence of two long‐period cyclicities of 1.6 and 3.4 Myr. These Early Jurassic cyclicities likely correspond to the Cenozoic orbital cyclicities of 2.4 Myr (g4–g3) and 4.7 Myr eccentricity terms. Shortening of eccentricity terms during the Early Jurassic is potentially related to the chaotic orbital motion of the inner planets expressed in the resonant argument θ = 2(g4–g3) − (s4–s3). The 1.6 Myr (g4–g3) cycle matches the third‐order eustatic sequences, whereas the 3.4 Myr cycle has no equivalent in the reference eustatic chart. These cycles of several million years are superimposed a cyclicity of ca. 7.5 Myr, which may correspond to the eccentricity term of 9.5 Myr, previously detected in the Cenozoic. Such cyclicity matches the global, 'shorter' second‐order sea‐level sequences and is strongly documented in the sedimentological and mineralogical proxy data, hence supporting the potential key role of orbitally paced climate and sea‐level changes at this timescale. [ABSTRACT FROM AUTHOR]

The article focuses on the history of Earth's atmospheric thermal tide, its composition, and mean temperature. It mentions the study explores the hypothesis that an atmospheric oscillation resonated with the Solar driving around 600 million years ago, affecting the length of the day. It highlight ny using global circulation models and geologic data, the researchers find evidence supporting the resonance hypothesis and provide insights into the Earth-Moon system's history.

In this communication, Earth temperature series in air and soil are analyzed and features that become convoluted with the known earth cycles of day-night and its orbit around the sun are separated. Atmospheric carbon dioxide concentrations are also considered. Earth weather changes (e.g., cloud, wind, rain, polar jet streams, and atmospheric pressure) in real time affect daily temperatures in a complex manner. A statistical model that accounts for autocorrelation and linear trend is evaluated together with empirical description of the series. Further graphical analysis is used to enhance remaining features and extreme events. Gaussian bell-shaped curve modeling of each year's daily profile is described. Further, Gaussian parameter-based anomalies are introduced together with soil anomalies at 30 cm depth. Semi-variogram components are shown along with folded percentile or mountain plots for data visualization. The Chow test is described for detection of any structural changes in data series. For much of the statistical analysis, temperatures observed daily are most appropriate because they carry variation due to earth, sea and sky weather over a single day-night earth rotation cycle. Also, the ever changing earth position along its orbital path captures a varying amount of solar energy, hence the shape of the temperature cycle as one sees it. Human activity and climate changing factors appear to affect temperature cycles within and over years. A double bell-shaped Gaussian curve fit can indicate climate changing effects of Earth life. [ABSTRACT FROM AUTHOR]

The semi‐enclosed marginal Japan Sea is sensitive to global changes and responds to orbital‐scale variability. Sediment core samples from Integrated Ocean Drilling Program Site U1423 were processed for detrital grain size and semi‐quantitative mineral analysis to assess the sediment characterization and depositional environment in the Japan Sea over the last 1200 ka. The mean grain data suggest the dominance of the silt size fraction over sand and clay in the whole period, while sand content increases dramatically between 600 and 150 ka. The end‐member energy modelling of grain size data suggests that sediment deposition took place under two energy conditions over the last 1200 ka. The low‐energy conditions observed during the middle Pleistocene transition (MPT) is mainly related to the wind deposition with the sediment characteristics being moderately to poorly sorted and coarse to nearly symmetrical skewed during global cooling and enhanced East Asian Winter Monsoon (EAWM) winds in the northern Japan Sea. Post MPT, periodic fluctuations between higher and lower energy conditions are observed, and the depositional environment is controlled by the EAWM wind, and precipitation intensity, glacio‐eustatic sea‐level changes and sea‐ice volumes. During the period, detrital sediments are poorly sorted and nearly symmetrically skewed, marked by the dominance of quartz, plagioclase and k‐feldspar. The spectral analysis grain size‐related data shows the presence of 228, 41 and 23 kyr orbital paced cycles, which are also observed in the Chinese Loess Plateau's normalized quartz mean grain size. This study is the first report of 228 kyr cycles from the Pleistocene Japan Sea sediments indicate that sediment deposition in the Japan Sea is associated with ~200 kyr eccentricity cycle as in the Chinese Loess Plateau. [ABSTRACT FROM AUTHOR]

The Zhujiang Formation in the Baiyun Sag, Pearl River Mouth Basin, China, is formed primarily in a deep-water continental slope environment. Its chronostratigraphic framework is based on biostratigraphy and sequence stratigraphy, and its geological dating is based on micropaleontological data. This makes it difficult to obtain precise absolute ages for various geological events. In this study, gamma ray (GR) well log data from Wells Y1, Y2, and Y3 were used as paleoclimate proxies, and spectral and wavelet analyses were used to conduct cyclostratigraphic research. The results show that the Milankovitch cycles were preserved in the Zhujiang Formation in the Baiyun Sag. Stratigraphic cycles controlled by 405 and 95 ka orbital eccentricity, 40.4 ka orbital obliquity, and 23.5 ka orbital precession cycles can be identified; the signal of stratigraphic cycles controlled by the 405 ka long eccentricity cycle is the strongest. The floating astronomical time scale is constructed based on 405 ka orbital eccentricity cycle tuning of the GR series. The precise durations of the Zhujiang Formation in Wells Y1, Y2, and Y3 are 7.13, 6.93, and 7.18 Ma, and the average deposition rates are 4.68, 5.91, and 5.33 cm/ka, respectively. The Zhujiang Formation was divided into 17 fourth-, 76 fifth-, and 174 sixth-order cycles using the 405, 95, and 40.4 ka orbital periods as the dividing scales, respectively. This study provides a quantitative method for high-precision isochronous stratigraphic division and correlation in deep-water sedimentary systems.

Climate oscillations preserved in sedimentary archives tend to decrease in resolution further back in Earth's history. High‐frequency climate cycles (e.g., ∼20‐Kyr precession cycles) are especially prone to poor preservation due to sediment reworking. Recent studies have shown, however, that given sufficient basin accommodation space and sedimentation rate, shallow‐marine paleoclimate archives record precession‐driven hydroclimate change in mid‐low latitude regions. Our study evaluates how the evolution of a rapidly uplifting orogen influences the recording of astronomical climate forcing in shallow‐marine sedimentary strata in the Taiwan Western Foreland Basin (WFB). Time‐series analysis of gamma‐ray records through the late Miocene–Pliocene Kueichulin Formation shows that during early stages of Taiwan orogenesis (before 5.4 Ma), preservation of precession‐driven East Asian Summer Monsoon variability is low despite increasing monsoon intensities between 8 and 3 Ma. The Taiwan Strait had not formed, and the southeast margin of Eurasia was open to the Pacific Ocean. Consequently, depositional environments in the WFB were susceptible to reworking by large waves, resulting in the obscuration of higher‐frequency precession cycles. From 5.4 to 4.92 Ma, during early stages of emergence of Taiwan, basin subsidence increased while sedimentation rates remained low, resulting in poor preservation of orbital oscillations. After 4.92 Ma and up to 3.15 Ma, Taiwan became a major sediment source to the WFB, and sheltered the WFB from erosive waves with the development of Taiwan Strait. The elevated sediment influx, increased basin accommodation as the WFB developed, and formation of a semi‐sheltered strait, resulted in enhanced preservation of precession‐driven East Asian Summer Monsoon variability. Plain Language Summary: Rhythmic changes in the shape of Earth's orbit (eccentricity, ∼100‐Kyr cycles), tilt (obliquity, ∼41‐Kyr cycles), and axial rotation (precession, ∼20‐Kyr cycles) drive climate change that may be preserved in sedimentary records. Orbital climate cycles are recorded in clastic shallow‐marine strata where the amount of sediment transported from land to sea and space available for deposition in the basin are sufficiently high. Our study of the Kueichulin Formation in the Taiwan Western Foreland Basin (WFB) shows how a rapidly uplifting orogen influences the preservation of different climate cycles in the shallow‐marine realm. During early Taiwan orogenesis (before 5.4 Ma) when the Taiwan Strait did not exist, sediment in the WFB were susceptible to reworking by erosive waves generated in the Pacific Ocean, which obscured higher‐frequency precession cycles. From 5.4 to 4.92 Ma, Taiwan began to emerge from the Pacific Ocean and the WFB began to subside, but sedimentation rates were low, so climate cycles were poorly preserved. After 4.92 Ma, rapid uplift and erosion of Taiwan and WFB subsidence continued, resulting in increased sedimentation to the sea, increased sediment accumulation space, and the formation of a strait that sheltered the WFB from waves, which all served to enhance the preservation of precession. Key Points: Preservation of different climate cycles in shallow‐marine records is influenced by a rapidly uplifting orogenDuring early uplift of Taiwan (before 5.4 Ma), only eccentricity and obliquity were preserved due to low sedimentation/basin accommodationFormation of a sheltered strait and increased sediment flux/basin subsidence as Taiwan uplifted enhanced preservation of precession cycles [ABSTRACT FROM AUTHOR]

The global climate of the early Oligocene was characterized by initiated Antarctic glaciation and meridional overturning circulation, which then led to profound eutrophication in the upper ocean. Generating a high‐resolution coccolith record helps to understand the responses of marine phytoplankton to the newly established environment. Using highly resolved (∼6 kyr time‐resolution) marine sediment samples from Deep Sea Drilling Project Site 522 in the South Atlantic Ocean, we conducted a comprehensive morphological study on coccoliths from the genera Reticulofenestra, Dictyococcites, and Coccolithus, which dominated the study interval between ∼33.1 and 32.8 Ma. Our results showed that the size variations of the three measured genera were significantly correlated (p < 0.01) with each other, indicating homogeneous responses to the environmental changes. Moreover, spectrum analysis on integrated morphologic data of all measured coccoliths showed distinct obliquity (∼40‐kyr) and precession (∼23‐kyr and ∼18‐kyr) cycles. We suggest that these variations were mainly driven by temperate, short‐term ecological fluctuations, which periodically altered the nutrient conditions in the common living habitats of the studied coccolithophores. We proposed two tentative explanations focusing on the obliquity signal. First, the cyclic variation could result from obliquity‐modulated changes in ice volume and variations in ocean circulation intensity, which influenced nutrient export from deep waters to the upper ocean. Alternatively, the changes in coccolith size may indicate the strength of seasonality that influenced upper ocean mixing on the west coast of South Africa. Plain Language Summary: Phytoplankton sizes yield important information to understand changes in marine ecosystems. Coccoliths, the fossil remains of unicellular algae coccolithophores, are preserved in marine sediments and thus are ideal for recording phytoplankton size changes in the past. We present a high‐resolution coccolith record spanning a period of ∼300,000 years in the early Oligocene (∼33 million years ago). Our data showed changes in coccolithophore sizes, corresponding to Earth's orbital cycles. We propose that the increased size of coccolithophore corresponded to nutrient‐rich conditions. Strengthened ocean circulation or enhanced wind‐driven mixing that is related to Earth's orbital cycles are two possible driving mechanisms for the nutrient increase in the upper ocean. Our study provides direct evidence of Earth's orbital forcings on the marine ecosystem in the early Oligocene when Antarctica started to be covered by a continental ice sheet. Key Points: This study presents a high‐resolution morphological record of early Oligocene coccolithophores in the South AtlanticThree measured coccolithophore genera showed homogenous responses to short‐term ecological fluctuationsOcean circulation and seasonality modulated by orbital forcing might have controlled the nutrient availability in the upper ocean [ABSTRACT FROM AUTHOR]

The Late Paleozoic Fengcheng Formation within the Mahu Sag of the Junggar Basin (China) harbors the world’s oldest alkaline lake hydrocarbon source rocks. Spectral analysis of the natural gamma-ray (GR) series obtained from four boreholes traversing the Fengcheng Formation, with wavelength ranges of 28.4 m–50 m, 5.9 m–12.6 m, 2.3 m–3.9 m, and 1.2 m–2.7 m. These were controlled by Early Permian astronomical cycles, including 405 kyr long eccentricity, 100 kyr short eccentricity, 34.2 kyr obliquity, and 20.7–17.4 kyr precession. The most significant cycle was notably that of the 405 kyr long eccentricity, which was instrumental for dividing and correlating the high-frequency sedimentary sequences in lacustrine shales. Nine intermediate-term and 36 short-term base-level cycles were identified in the P1f1 and P1f2 members of the Fengcheng Formation. These cycle types are equal to the 405 kyr long eccentricity cycle and ∼100 kyr short eccentricity cycle, respectively. The paleolake-level variations in the Fengcheng Formation were reconstructed using sedimentary noise modeling, revealing that lake levels reached their highest value during the deposition of the P1f2 Member. The spatial distribution patterns of lithofacies in the Fengcheng Formation can be clearly demonstrated within the isochronous cycle framework under the constraints of long eccentricity cycles. The use of astronomical cycles in isochronous stratigraphic correlation offers great potential for characterizing alkaline lacustrine sequences and predicting favorable areas for shale oil exploration with higher accuracy.

The continuous sedimentary cores recovered at the International Ocean Discovery Program (IODP) Site U1505, Expedition 368, provide an opportunity for paleoceanography and paleoclimate reconstruction in the continental margin of the northern South China Sea (SCS). In this study, we conducted detailed rock‐ and paleomagnetic studies on 420 discrete samples from the top ∼200 m of the synthetic records of Holes U1505C and U1505D. Rock magnetic analyses indicate that low‐coercivity pseudosingle domain magnetite dominates as the primary ferromagnetic mineral of Site U1505. The magnetostratigraphic age model was constructed by correlating the interpreted polarity sequence with the Geomagnetic Polarity Time Scale 2020 with the constraints of the biostratigraphic data and the distribution probability of the age of each polarity zone provided by a Dynamic Time Warping algorithm. The Milankovitch cycles of the short eccentricity, obliquity, and precession cycles were identified in the magnetic susceptibility (MS) and natural gamma radiation (NGR) series based on paleomagnetic results. We established an ∼9 Myr high‐resolution astronomical time scale by tuning the MS and NGR records to the global oxygen isotope curves, the obliquity, and the eccentricity curves of the La2004 astronomical solution. Our new age model reveals detailed sedimentation rate variations and a ∼500 kyr hiatus across the Brunhes‐Matuyama boundary related to local tectonic activity. These results lay the foundation for understanding the paleoceanography and paleoclimate evolution of the SCS. Plain Language Summary: A high‐resolution time framework is essential for achieving the scientific objectives of the International Ocean Discovery Program Expedition 368 in the northern South China Sea. Here we conducted detailed magnetostratigraphic and cyclostratigraphic analyses on cores of Site U1505, providing a robust age constraint of the upper ∼200 m of the cores. Our results provide an almost continuous succession since ∼9 Ma with a ∼500 kyr hiatus at ∼30.517 m. Significant Milankovitch cycles corresponding to the short eccentricity, obliquity, and precession cycles were identified in the geophysical data, indicating an orbital forcing on the monsoon climate and terrigenous input variations over the northern South China Sea. The new magneto‐cyclostratigraphic age model will contribute to further paleoceanographic, paleoclimatic, and correlation studies. Key Points: Rock magnetic studies indicate that magnetic remanence is dominated by low‐coercivity magnetite in International Ocean Discovery Program Site U1505The fluctuation of the content of terrigenous materials over the northern South China Sea is driven and modulated by Milankovitch cyclesA new magneto‐cyclostratigraphic age model since ∼9 Ma is established, highlighting a ∼500 kyr hiatus across the Bruhnes/Matuyama boundary [ABSTRACT FROM AUTHOR]

Peatlands, an important organic carbon reservoir, play a crucial role in the global carbon cycle. The carbon accumulation of peatlands, reflected by net primary productivity (NPP), can have an impact on global carbon cycling and climate change. The late Carboniferous - early Permian is an icehouse period, during which numerous thick coal beds were accumulated in the North China Block (NCB) located within a low-latitude area, providing an opportunity for studying the carbon cycling under the glacial and interglacial climates. In this study, spectral analysis was performed on the natural gamma-ray (GR) logs of the Benxi, Taiyuan, and Shanxi formations of the late Carboniferous to early Permian in a borehole section located within the Ordos Basin in western NCB. Cyclic signals related to astronomical orbital parameters were identified, including long eccentricity (∼405 kyr), short eccentricity (∼125 kyr and ∼ 95 kyr), and obliquity (∼35.5 kyr). A floating astronomical time scale was established by using the long eccentricity signal, and this time scale was further used to constrain the durations of the accumulation of coal-forming paleo-peatlands. The paleo-peatland for the C 8+9 coal seam (9 m thick) of the Taiyuan Formation lasted approximately 203 kyr, and the paleo-peatland for the C5 coal seam (4 m thick) of the Shanxi Formation lasted approximately 46 kyr. Using this timeframe and an estimation of carbon loss during coalification, the carbon accumulation rates of the late Carboniferous - early Permian low-latitude peatlands are calculated to be 104.7 ± 14.9 g· C ·m−2·a−1for the C 8+9 coal seam and 192.6 ± 11.6 g· C ·m−2·a−1for the C 5 coal seam. The NPP of the paleo-peatlands, which deducts a part of the carbon loss caused by the loss of CO 2 and CH 4 , can be calculated from the carbon accumulation rates. The calculated average NPP of the paleo-peatlands for the C 8+9 seam was 199 ± 28 g· C ·m−2·a−1, and that of the C 5 seam was 366 ± 22 g· C ·m−2·a−1. In combination with the absolute time scale calibrated by high-precision U Pb dates from Palougou section in western NCB, the depositional time of the investigated strata was constrained to be from 300.1 ± 0.5 Ma to 294.3 ± 0.5 Ma. The coal seams of the late Carboniferous to early Permian in the NCB correspond to an interglacial interval around ∼298 Ma. The peatland with a lower NPP corresponds to the warming stage and the peatland with a higher NPP corresponds to the cooling stage. This implies that a lower NPP of paleo-peatland tends to be less efficient in carbon storage, and could not reduce the atmospheric CO 2 substantially. In contrast, a higher NPP of paleo-peatland tends to accelerate carbon fixation, leading to temperature decrease and the termination of interglacial interval in early Permian. The results of this study could provide insights into the relationship between the development of paleo-peatlands and the record of the paleoclimates during the same period, and could be helpful for the prediction of future climate change. • The astronomical scale is used to constrain the ages of Permo-Carboniferous coal measures. • Net primary productivity (NPP) of paleo-peatlands for coal seams can be estimated with these ages. • The rising NPP of low-latitude peatlands led to the termination of deglaciation in the early Permian. [ABSTRACT FROM AUTHOR]

• Total organic carbon (TOC) data show astronomical cycles of 1.2 Myr in East Asia. • Higher lake levels favoured organic carbon burial. • Orbital forcing is a key driver of organic carbon burial in terrestrial basins. Carbon sources and sinks are primary components of the climate system, but their response to external forcing remain unconstrained, especially for past greenhouse climates. Lakes are important carbon sinks that play a key role in the global carbon cycle. In this study, we investigate organic carbon burial processes and the possible role played by astronomical forcing in low to middle latitude lakes in China during the Eocene. Sediment noise modeling of lake level fluctuations in the three basins suggests that TOC maxima coincided with lake level maxima. We suggest that elevated lake levels likely led to stagnation of bottom waters, thereby promoting the development and preservation of organic matter. Total organic carbon (TOC) data spanning the Eocene from three borehole cores of separate basins show a common cyclicity of ∼1.2 Myr. According to the three TOC time series studied, maxima in TOC are linked to maxima in long-term 1.2 Myr obliquity modulation cycles, with long-term 2.4 Myr eccentricity cycles either at a maxima or minima. Our analysis elucidates a likely control on the burial of organic carbon by long-term astronomical climate cycles. The superposition of different orbital cycles may have driven the process of differential enrichment of organic matter by inducing perturbations in the carbon cycle through nonlinear climate effects. Overall, our chemostratigraphy results illustrate the sensitivity of the terrestrial carbon cycle to orbital forcing on geological timescales. [ABSTRACT FROM AUTHOR]

The Cambrian period is an important era in geological history, marked by numerous major geological and biological events. To better understand these events, it is important to establish a high-precision chronostratigraphic framework. An astronomical time scale can be created by the identified Milankovitch cycles in well-preserved stratigraphic successions. Duibian B section in Jiangshan (Zhejiang Province, China) is the global stratotype section and point (GSSP) for the Jiangshanian Stage, and this section provides well-preserved records covering the upper Paibian to lower Jiangshanian stages. In this study, we use high-resolution magnetic susceptibility record to conduct cyclostratigraphic analysis of the Duibian B section. Our results indicate that the 2.44 m, 0.84–0.73 m, 0.20–0.19 m, and 0.12–0.09 m sedimentary cycles may represent long-eccentricity, short-eccentricity, obliquity, and precession cycles, respectively. Using the stable 405-kyr eccentricity cycles, we constructed an ∼5.96 Myr floating astronomical time scale to calibrate agnostoid trilobite zones. In addition, we reconstructed the precession rate k from geological records, and our result provides an insight into the Earth-Moon distance and length of day in the late Cambrian (Paibian–Jiangshanian, ∼494.2 Ma). It enriches our understanding of the Earth-Moon evolutionary history in deep time. • Milankovitch cycles were identified in the late Cambrian marine strata. • An ∼5.96 Myr ATS was constructed for geological events during the Paibian–Jiangshanian time. • Deep-time evolution of the Earth–Moon system was reconstructed. [ABSTRACT FROM AUTHOR]

Interannual-to millennial-scale climate cycles have been recognized in ancient sedimentary strata and may be closely associated with solar activity. However, the physical driving mechanisms of such cycles remain a mystery. To better understand the nature and evolution of suborbital cycles in ice-free conditions, we performed a quantitative analysis of high-resolution phosphorus (P), gray-scale values, and iron (Fe) data obtained from a core deposited in a mid-latitude lake (Funing Formation of the Subei Basin) during the Late Paleocene-Early Eocene. Time series analysis reveals evidence for ∼88-yr and ∼ 11-yr solar activity cycles in the gray value data, and ∼ 20-kyr precession cycles, ∼10-kyr half-precession cycles, and ∼ 2-kyr solar activity cycles in the Fe data. The data indicate that paleoclimate changes in the Subei Basin at this time were driven by both orbital and suborbital cycles. Amplitude modulation analysis suggests that ∼20-kyr precession modulated the amplitude of the observed 2-kyr cycles. It is inferred that the Earth's climate is driven not only by eccentricity-modulated precession cycle, but also by precession-modulated millennial cycles. • Terrestrial late Paleocene-early Eocene strata record changes in solar activity. • Palaeoclimate changes in the Subei Basin were driven by orbital and suborbital cycles. • Millennial-scale solar cycles are modulated by orbital cycles. [ABSTRACT FROM AUTHOR]

Exploring the interdependence between watermass conditions and climate change in marginal marine regions is essential for gaining insights into contemporary environmental challenges arising from global warming. Salinity, a key parameter of watermass conditions in coastal areas, plays a crucial role in influencing nutrient availability, stratification, and the spatial-temporal distribution of redox conditions. Here, we focus on the cyclostratigraphic analysis of gamma-ray (GR) data obtained from Eocene strata in the Luo-69 drillcore from the Bohai Bay Basin (NE China). This analysis establishes a high-resolution astronomical time scale (ATS) for the lower third member of the Shahejie Formation (Es3l), spanning 39.04 Ma to 41.46 million years ago (Ma). Various proxies for watermass conditions, such as salinity, sedimentary structures, mineral content, total organic carbon (TOC), organic carbon isotopes and nitrogen isotopes (δ13C org and δ15N), exhibit a strong correlation with 405-kyr long orbital eccentricity climate forcing. Notably, spectral analysis of salinity data (represented by the Sr/Ba proxy) reveals a clear astronomical control, with 405-kyr eccentricity cycles that align closely with variations in the GR data. Peaks in paleosalinity, as indicated by Sr/Ba (as well as B/Ga and S/TOC), correspond with maxima in 405-kyr long orbital eccentricity cycles in the GR data. As such, we infer that astronomical forcing regulated long-term changes in watermass conditions, likely through mediation of the East Asia monsoon system. Specifically, during eccentricity maxima, the basin would have experienced a warm and humid climate with pronounced seasonality and a robust summer monsoon. During such periods, increased continental runoff would lead to a rise in lake-levels, facilitating better connections with the ocean, and hence increased salinity. By contrast, during eccentricity minima, cooler and more arid conditions with weaker seasonality would result in lower lake levels which together with a global eustatic lowstand would result in as weakened connection with the open ocean restricting the ingress of seawater into the basin lowering salinity. Our dataset spans the Middle Eocene Climatic Optimum (MECO, ∼40.60–40.10 Ma), identified by elevated GR values and a conspicuous negative excursion in oxygen isotopes. This interval is characterized by a significant decline in salinity, likely attributed to enhanced freshwater runoff driven by an extremely warm and humid climate. The paleosalinity fluctuation recorded by the proxies B/Ga, Sr/Ba, and S/TOC in Bohai Bay Basin demonstrate the sensitivity of marginal-marine environment to subtle changes in climate driven by astronomical forcing. Our results provide new insights into how elemental salinity proxies can be utilized in paleoenvironmental reconstruction studies. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of sedimentary successions and paleoenvironmental indicators in two wells, Rh3 and Rh46, located in NE Jordan, within the context of the Ordovician-Silurian boundary transition. By integrating spectral analysis, cyclostratigraphy and sedimentary architecture, significant shifts and cyclical patterns are identified, shedding light on paleoenvironmental changes and orbital forcing dynamics. The study reveals distinct lithological and geochemical signatures at the Risha/Mudawwara (Hirnantian/Rhuddanian) boundary, indicative of major shifts in depositional environments. Analysis of Milankovitch cycles suggests orbital forcing as a driver of sedimentary cyclicity, with implications for understanding climatic variations during the Ordovician-Silurian transition. Spectral analysis revealed significant cycles with different periodicities. Testing the sediment accumulation rates (SAR) revealed an optimum SAR at 5.9 and 4.6 cm/kyr in Rh3 and Rh46 wells, respectively. A new refined astronomical time scale (ATS) is created based on the 100 kyr eccentricity cycle. The new ATS assigns the Risha Formation to the Hirnantian age and revealed a probable time gap at the base of Risha Formation of about 0.3 myr in Rh46 well; deposition of the Risha Formation commenced at 444.88 myr and 444.58 myr in Rh3 and Rh46 wells, respectively, with sedimentation continuing up to the Ordovician/Silurian boundary at 443.07 myr. The Ordovician/Silurian transition experienced shortening in the obliquity and precession cycles. The tuned data show that the 41, 36 and 31 kyr obliquity cycles, in addition the 21, 19 and 16 kyr precession cycles, were recognised. Furthermore, 740, 425, 250, 147 and 100 kyr eccentricity cycles were also recognised. Notably, the study identifies the glacial/fluvioglacial Risha Formation is bounded by g4-g3 eccentricity nodes coinciding with Hirnantian stage boundaries that correspond to significant geological events, such as the Late Ordovician Mass Extinction and the Hirnantian glaciation events. The g4-g3 eccentricity cycle is estimated to be 1.8 myr. Surprisingly, the lower Silurian OAE coincided with the g4-g3 eccentricity node at the Ordovician/Silurian transition. Additionally, the application of DYNOT modelling has elucidated sea-level fluctuations and their relationship with sedimentary sequences, highlighting the role of tectonic and climatic factors in shaping the sedimentary architecture. Furthermore, the investigation of Th/U and Th/K ratios provides insights into marine and terrestrial depositional settings. • Sedimentary Successions Analysis in NE Jordan's Rh3 and Rh46 Wells. • The Ordovician-Silurian boundary transition characterised by significant shifts and cyclical patterns. • Integration of spectral analysis, cyclostratigraphy, and sedimentary architecture..• Revelation of distinct lithological and geochemical signatures at Risha/Mudawwara boundary. • Milankovitch cycle analysis suggests orbital forcing as sedimentary cyclicity driver. [ABSTRACT FROM AUTHOR]

Today and in the geologic past, climate changes greatly affect and have affected Earth surface processes. While the climatic parameters today can be measured with high precision, they have to be interpreted from the sedimentary record for ancient times. This review is based on the detailed analysis of stratigraphic sections of Oxfordian (Late Jurassic) age, with the aim to reconstruct and discuss the climate changes that controlled the sedimentation on the shallow marine carbonate platform that today is represented in the Swiss Jura Mountains. The sediments formed under subtropical conditions in which carbonate-producing organisms proliferated, and ooids and oncoids were common. The sections are composed of hierarchically stacked elementary, small-scale, and medium-scale depositional sequences wherein facies changes imply deepening–shallowing trends. The major sequence boundaries Ox 6, Ox 7, and Ox 8 can be correlated with those of other European basins and place the studied sections in a broader framework. The chronostratigraphic tie points imply that the medium- and small-scale sequences formed in tune with the orbital eccentricity cycles of 405 and 100 kyr, respectively, and the elementary sequences with the precession cycle of 20 kyr. Orbitally controlled insolation changes at the top of the atmosphere translated into climate changes: low insolation generally resulted in low amplitudes of sea level fluctuations at the 20 kyr frequency and in a cool and humid climate at the palaeolatitude of the Jura platform. Terrigenous material was eroded from the hinterland and distributed over the platform. High insolation led to sea level rise, as well as to warm and semiarid to arid conditions in which coral reefs could grow. However, nutrient input favoured growth of microbialites that encrusted the corals. The reconstruction of high-frequency sea level fluctuations based on facies analysis compares well with the curve of insolation changes calculated for the past 550 kyr. It is therefore assumed that the sea level fluctuations were mainly due to thermal expansion and retraction of ocean surface water. Two models are presented that explain the formation of elementary sequences: one for low and one for high insolation. Despite the important lateral facies variations typical of a shallow marine platform, and despite the uncertainties in the reconstruction of sea level changes, this study demonstrates the potential of carbonate ecosystems to record past climate changes at a time resolution of 20 000 years. Relatively short time windows can thus be opened in the deep geologic past, and processes and products there can be compared with those of the Holocene and the Anthropocene. For example, it appears that today's anthropogenically induced sea level rise is more than 10 times faster than the fastest rise reconstructed for the Oxfordian. [ABSTRACT FROM AUTHOR]

The long-term history of the Earth–Moon system as reconstructed from the geological record remains unclear when based on fossil growth bands and tidal laminations. A possibly more robust method is provided by the sedimentary record of Milankovitch cycles (climatic precession, obliquity, and orbital eccentricity), whose relative ratios in periodicity change over time as a function of a decreasing Earth spin rate and increasing lunar distance. However, for the critical older portion of Earth’s history where information on Earth–Moon dynamics is sparse, suitable sedimentary successions in which these cycles are recorded remain largely unknown, leaving this method unexplored. Here we present results of cyclostratigraphic analysis and high-precision U–Pb zircon dating of the lower Paleoproterozoic Joffre Member of the Brockman Iron Formation, NW Australia, providing evidence for Milankovitch forcing of regular lithological alternations related to Earth’s climatic precession and orbital eccentricity cycles. Combining visual and statistical tools to determine their hierarchical relation, we estimate an astronomical precession frequency of 108.6 ± 8.5 arcsec/y, corresponding to an Earth–Moon distance of 321,800 ± 6,500 km and a daylength of 16.9 ± 0.2 h at 2.46 Ga. With this robust cyclostratigraphic approach, we extend the oldest reliable datum for the lunar recession history by more than 1 billion years and provide a critical reference point for future modeling and geological investigation of Precambrian Earth–Moon system evolution. [ABSTRACT FROM AUTHOR]

The chaotic behavior of the Solar System prevents the prediction of the precise evolution of the planetary secular frequencies. Here we use four cyclostratigraphic sequences, ∼259 Ma Wujiaping Formation, ∼455 Ma Pingliang Formation, ∼655 Ma Datangpo Formation and ∼2,465 Ma Dales Gorge Member, and Bayesian inversion to provide powerful geological constraints to this problem. The inversion provides constraining estimates for the Solar System fundamental secular frequencies g1, g2, g3, g4, and g5, and the Earth's precession rate k from 105.26 ± 2.68 (2σ) arcseconds/year at ∼2,465 Ma to 55.86 ± 2.60 (2σ) arcseconds/year at ∼259 Ma. Stochastic monotone interpolation enables the reconstruction of Earth‐Moon distance from 2.5 billion years to the present. Calculation of tidal dissipation supports the ocean model before 1.4 Ga, but is outside the error range after ∼1.8 Ga, suggesting lower tidal dissipation in the early Proterozoic Eon, and a possible high value in the early Paleozoic. Plain Language Summary: The chaotic history of the Solar System imposes unknown uncertainties on the fundamental secular frequencies of the planets over most of geologic time. This is complicated by a lack of knowledge about the evolution of Earth‐Moon distance, Earth's length of day and tidal dissipation. Geological evidence provides powerful constraints on all of these parameters. To shed light on the parameters, here we carry out Bayesian inversion of fundamental secular frequencies and Earth precession rate on four cyclostratigraphic sequences, and stochastic monotone interpolation to reconstruct Earth‐Moon distance from 2.5 billion years ago to present. From these results we estimate the Earth's tidal dissipation variation, which we compare with theoretical models. Our results provide critical geological constraints for paleotidal simulation, and shine a light on the unique potential of cyclostratigraphy to constrain Earth‐Moon system history across geologic time. Key Points: We obtain new estimates of Earth‐Moon and Solar System dynamical parameters from cyclostratigraphy at four ages from ∼2.5 Ga to ∼259 MaWe interpolate Earth‐Moon distances inferred from the cyclostratigraphy to reconstruct a continuous history from ∼2.5 Ga to the presentWe estimate Earth's tidal dissipation variations from ∼2.5 Ga to the present [ABSTRACT FROM AUTHOR]

• Unveils how orbital signals are preserved in sedimentary strata. • Highlights the 405-kyr cycle's reliability in ATS. • Demonstrates the impact of sedimentation rates on ATS resolution. Orbital forcing, a primary climatic driver, imprints discernible signatures in sedimentary strata that are instrumental for elucidating climatic change mechanisms and establishing high-resolution astronomical time scales (ATS). Our research dives into sedimentology and cyclostratigraphy, tackling the longstanding enigma of how orbital signals survive in dynamic environments where sediment deposition occurs at highly variable rates. Utilizing a stochastic sedimentation model, we simulate stratigraphic records containing orbital rhythms, representative of a range of depositional settings. We show that the 405-kyr eccentricity cycle is often the most reliably preserved, and sometimes even the sole trustworthy metronome in devising ATS among various tuning strategies. This holds particularly true in environments with high energy and unsteady sedimentation, such as fluvial or deltaic settings. In contrast, environments with lower sedimentation rate variability and higher overall sedimentation rates allow for the use of shorter-period orbital parameters in astronomical tuning, thereby enhancing the temporal resolution of ATS. This study has implications not only for decoding past climate forces but also for refining the precision of ATS, contributing significantly to our understanding of Earth's geological history. [ABSTRACT FROM AUTHOR]

The Oceanic Anoxic Event 2 (OAE 2) is widely regarded as one of the most significant global-scale biological and environmental perturbations in the Mesozoic Era. However, the duration and driving mechanisms of this event at southern high latitudes remain largely unknown due to a lack of available geological records. Here, we present a cyclostratigraphic analysis of high-resolution records of lightness variability (L*) and gamma-ray attenuation (GRA) bulk density, which are associated with changes of marine primary productivity and continental weathering, respectively, from Site U1516 located in the Mentelle Basin, offshore southwest Australia. This analysis permits establishment of an astronomical time framework for a stratigraphic interval of 455.205–485.24 m rCCSF (revised Core Composite Depth below Sea Floor) by tuning the 100 kyr filter to short eccentricity. The studied section encompasses the entire OAE 2 interval at the depth of 460.13–473.94 m rCCSF. Based on the established high-resolution astronomical time scale using astronomical tuning of L* records to the short eccentricity cycles (100 kyr), the duration of OAE 2 is estimated to be ∼990 kyr at Site U1516. A relatively high amplitude of short eccentricity occurred at the build-up stage, accompanied by a gradual rise in obliquity amplitude during the recovery phase of the OAE 2. Combining previous proposals for enhanced oceanic water stratification and terrestrial weathering, we suggest that obliquity, coupled with short eccentricity, paced the evolution of this event at southern high latitudes by controlling insolation changes received by the Earth's surface. • The OAE 2 duration is ∼990 kyr at southern high latitudes. • Short orbital eccentricity amplified the large igneous province affection at the OAE 2 build-up stage. • The orbital obliquity paced the OAE 2 recovery stage at southern high latitudes. [ABSTRACT FROM AUTHOR]

The coal‐bearing Yan'an Formation in the Ordos Basin of the Middle Jurassic was deposited in a river delta–lacustrine sedimentary environment with relatively stable accumulation rates. Spectral analysis and wavelet transform analysis of the natural gamma‐ray (GR) curves from several boreholes through the Yan'an Formation yielded five main sedimentary cycles with wavelengths of 34–57, 10–18, 8–14, 2.9–4.1, and 2–3 m. These cycles were controlled by orbital cycles of eccentricity (405, 128, and 97 kyr), obliquity (35 kyr), and precession (22 kyr), and the long‐eccentricity period of 405 kyr was the most significant cycle. Filtering the sedimentary records for the long‐wavelength cycle and short‐wavelength cycle implies that there are 11 long‐eccentricity cycles and 35 short‐eccentricity cycles preserved in the Yan'an Formation. Assigning the 405 kyr long‐eccentricity cycle to the filtered 11 primary long‐wavelength cycles implies that the Yan'an Formation spanned 4.4 Myr. The orbital–climate cycles were critical factors in the sediment facies changes and episodes of coal formation within the basin. The long‐eccentricity cycles of the Milankovitch cycle are the predominant control factors of the coal seams deposited in the Middle Jurassic Yan'an Formation. [ABSTRACT FROM AUTHOR]

Time indications for the correlation and calibration of the Rotliegend of Germany are integrated and presented in a new way. The correlations are based on the visual balance of bio- and ecostratigraphic indications and radio-isotopic age determinations (RIA), whereby confidence limits, equivalent to those of the RIA, are applied also for other time indications (conchostracans, aquatic tetrapods, fishes, insects, macroflora, and ecostratigraphic indications). In contrast, terrestrial tetrapods and their tracks, chemo- and sequence stratigraphy, and magnetic susceptibility did not contribute to correlations in the Rotliegend in Central Europe. The Illawarra Reversal of the Earth' magnetic field (≈ 265 Ma) is fundamental for correlation and calibration. In general, however, the Regional Stratigraphic Scale is calibrated using U-Pb CA-ID-TIMS-RIA on zircon, Ar-Ar- and Rb-Sr-based RIA and, in addition, in the Early and Late Rotliegend using orbital-climatically controlled eccentricity cycles (≈ 100 ka, ≈ 400 ka). The boundary ages of the subgroups and of most formations are rounded to 0.5 Ma to avoid overinterpretation. Because of some inconsistent time indications alternative interpretations are also offered. The hitherto differing ages for the global Carboniferous-Permian boundary are the result of different dating methods: The ≈ 296 Ma in the Stratigraphic Tables of Germany 2002 and 2016 A (STG 2002; STG 2016 A) is an integrative age based on RIA from Central Europe, whereas the ≈ 299 Ma in the Global Stratigraphic Scales 2004 ff. and the STG 2016 B is based on a CA-ID-TIMS RIA on zircon from the southern Ural area. The age of ≈ 299 Ma is plausible from the perspective of the current Rotliegend RIA because the Rb-Sr age of 290.7 ± 0.9 Ma for the Donnersberg Formation (Lippolt & Hess 1989) has been replaced by the age of 294.5 ± 2.2 Ma, as recalculated in the present work. The updated time scale developed here will be integrated in the Stratigraphische Tabelle von Deutschland Kompakt 2022 (STDK 2022) and into the Stratigraphic Table of Germany Compact 2022 (STGC 2022). The age of the base of the Rotliegend in the Saar-Nahe Basin (SN, base Remigiusberg Formation and Glan Subgroup) is ≈ 299 Ma (U-Pb CA-ID-TIMS, zircon) resp. ≈ 300 Ma (Ar-Ar); the balanced compromise age of both is ≈ 299.5 Ma. In the Thüringer Wald (TW), the Rotliegend begins with the Ilmenau Formation (Subkommission Perm-Trias 2011) at ≈ 299.5 Ma (U-Pb CA-ID-TIMS). On the Flechtingen Block, at the southern margin of the Central European Basin, the oldest volcanic rock of the Altmark Subgroup is dated at 302 ± 3 Ma (U-Pb SHRIMP data). Accordingly, the Rotliegend in the STG 2002 and STG 2016 A starts at ≈ 302 Ma. However, the mean age calculated in the present work for the SHRIMP data of Breitkreuz & Kennedy (1999) is 298.6 ± 1.9 Ma, so that the base of the Altmark volcanic succession is here re-dated as ≈ 300.5 Ma. Thus, the ages of the present lithostratigraphic lower limits of the Rotliegend in northern Germany (CEB), in the TW and in the SN are, with ≈ 300.5 Ma to ≈ 299.5 Ma, only weakly diachronous if the nominal (face) values, which are both in the latest Carboniferous, are compared without the confidence intervals. For the first time, the Rotliegend of Germany is geochronologically subdivided into Early (≈ 300.5-295.5/294 Ma), Middle (≈ 295.5/294-266 Ma) and Late Rotliegend (≈ 266-257.5 Ma). The very long lasting Middle Rotliegend includes numerous and also extremely long stratigraphic gaps as a result of the amalgamation and the associated immense uplift of Pangaea in the area of Central and Western Europe. A very large stratigraphic gap in the Central European Basin (CEB) of ≈ 15 Ma (≈ 281-266 Ma, here called the Pangaea Gap) is supported by conchostracans, the Illawarra Reversal and the different palaeomagnetic properties of the sediments below and above the gap, which are discussed here for the first time. The Middle Rotliegend (duration of ≈ 29.5/28 Ma) is approx. twice as long as the Early (≈ 5.5/7 Ma) and Late Rotliegend (≈ 8.5 Ma) combined. The latter, however, contain the thickest successions in the Saar-Nahe Basin and the Central European Basin, respectively, which are free of gaps in the basin centre, with 'gaps' being defined in this context as time spans of ≤ 100 ka and ≤ 400 ka, respectively. In the CEB, the Elbe Subgroup is cyclostratigraphically calibrated to 5.6 Ma. A gapless area in the Saar-Nahe Basin is the Glan Subgroup, which covers only 4 Ma and 3 Ma, respectively; correspondingly, its subunits G1 to G10 (Glan 1 to Glan 10), introduced here, last on average 0.4 Ma and 0.3 Ma, respectively. This results in a maximum accumulation rate of 870 Bubnoff (Bub, m/Ma, mm/ka) and of 1150 Bub, respectively, which can be explained by a maximum of tectonic activity along the Hunsrück Southern Border Fault. For the lower Nahe Subgroup (N1 to N5, Nahe 1 to Nahe 5), the maximum accumulation rates are ≈ 450-200 Bub and for the upper Nahe Subgroup (N6-N8), at an estimated duration of 12 Ma ≈ 125 Bub and ≈ 50 Bub at a duration of 30 Ma, respectively. In the Central European Basin the maximum accumulation rates are much lower compared to the Glan Subgroup, with 200 Bub in the Elbe Subgroup and ≈ 360 Bub in the Havel Subgroup (Fig. 27), although here the subsidence rate may have been higher than the accumulation rate, as the basin was ≈ 130 m below sea level at the end of Folge ro4 (Top of the Hannover Formation; this paper). We recommend (1) Bubnoff (Bub) as unit of measure of the accumulation rate and (2) the stratigraphic terminology of the Subkommission Perm-Trias (2011) and the STG 2016 A. We here propose that numerous tuffs of the Glan Subgroup could originate from volcanic centres of the TW, whereas so far only source areas south of the SN were discussed: On the one hand, the tuff-rich time of the upper Jeckenbach Subformation - Odernheim Formation (= Glan units 7 and 8 = G7/G8) seems to correlate with the volcanogenic Oberhof time in the TW and, on the other hand, the tuff-poor time of the Wahnwegen Formation - middle Jeckenbach Subformation (G2/G6) seems to correlate with the upper Ilmenau, Manebach, Goldlauter and lowest Oberhof formations, which are devoid of volcanic rocks in the TW. Should causality exist here, an additional and also precise criterion for correlation would be established. At present there are two variants: On the one hand, volcanism in the Oberhof Formation, according to RIA (U-Pb CA-ID-TIMS on zircon), begins ≈ 1.8 Ma earlier and ends ≈ 0.8 Ma earlier than in the Donnersberg Formation (Ar-Ar, Rb- Sr recalculated). On the other hand, the conchostracan Lioestheria pseudotenella in the TW, if considered equivalent to L. cf. pseudotenella in the SN, the ecostratigraphic and lithofacial indications and the aquatic tetrapod D. pulcherrimus, point to for a similar age of these magmatites. The Sobernheim Lens (SN, Nahe units N4/N5) with its fossils so important for correlations is here assigned to the Jakobsweiler Member (N4, upper Donnersberg Formation), to the Quartzite-Conglomerate (N5, in literature often Wadern) and to the lowermost Standenbühl Formation (N4/N5). The youngest time indication Co13, the conchostracan Lioestheria arroyoensis sp. nov. correlates the upper Standenbühl Formation (N8, Martens 2020, where N8 may be extremely long), roughly with the Arroyo Formation in Texas (≈ early Kungurian). The here favoured age of the Tambach Formation of ≈ 294-292 Ma is significantly higher than the ≈ 286-283 Ma of STG 2016 A and the ≈ 284-281 Ma of STG 2016 B. It is based on RIA R25 (Table 9; lower Rotterode Formation, 295.8 ± 0.4 Ma; Lützner et al. 2021), which is the youngest CA-ID-TIMS RIA in the TW, and the duration estimate of the Rotterode - Tambach gap. In the SN, the youngest RIA R29 (Rb/Sr) is from the Donnersberg Formation (294.5 ± 2.2 Ma, this paper). From here on until ≈ 265 Ma (Illawarra Reversal), the numerical ages of all Rotliegend units and their connection to the Global Stratigraphic Scale (GSS) are uncertain and therefore correlations between Central Europe and the global reference section in the southern Ural area, partly biostratigraphically via North America, vary greatly. In this contect, the „series“ Wolfcampian and Leonardian (standard Permian units of the USA) played an important role. However, these lithostratigraphic units are at least unsuitabel as a reference system for large parts of North America, because they represent very variable time spans from region to region, similar with the "Lower Rotliegend" ("Autun") and "Upper Rotliegend" ("Saxon") of Central and Western Europe and therefore their assignement to the GSS is also very variable. This is due, among other things, to the fact that the Wolfcampian is often still understood as "lower Lower Permian", although considerable parts of it are now placed in the Carboniferous, because as a result of the introduction of the Global Stratigraphic Section and Point (GSSP) for the base of the Asselian Stage (= global base of the Permian in the southern Ural area), the conventional regional Carboniferous-Permian boundaries shifted to an higher stratigraphic level and thus to a younger age in the USA, China and the Donbass (Fig. 14). If the 57 sedimentary cycles in the Ottweiler and Glan subgroups (Königer & Stollhofen 2001: mean duration 245 ka each) in the SN are orbital-climatically induced, these cycles can only be 100 ka cycles (short eccentricity). This is also supported by the 6 cycles in units G7 and G8 that have been described in detail in the literature, which are consistent with the duration of the Glan Subgroup of 3 Ma and (preferred) 4 Ma, respectively. The total duration to be expected from 57 cycles à ≈ 100 ka is ≈ 5.7 Ma in contrast to the duration determined here according to RIA of ≤ 8 Ma. One reason for the difference could be that in the Ottweiler und Glan subgroups there are cycles that have not been recorded so far. The time span of ≤ 8 Ma is also an outcome of the new estimate for the duration of the Cantabrian Gap (early Stephanian) in the Saar-Nahe Basin of ≈ 3.6 Ma that is clearly longer than proposed in the STG 2002 and STG 2016. [ABSTRACT FROM AUTHOR]

Abstract The Zakeen Formation is one of the possible gas reservoirs in the Zagros sedimentary basin. In this paper, the cyclostratigraphic study of the upper part of the Zakeen Formation was performed by using evolutionary spectral analysis methods. The Multi-Tapper Method (MTM) periodogram is one of the evolutionary spectral analysis methods used in this study to identify and prove the frequency ratios of Milankovitch cycles in the studied sediment sequences. In this study, using the introduced methodology, the frequency ratios of the Milankovitch cycles in the upper part of the Zakeen Formation was identified for the first time, and their existence was confirmed. Besides, the spectral powers of spectral gamma-ray (SGR) and density (RHOB) series, in evolutionary Fast Fourier Transform (FFT) and Wavelet Transform (WT) Scalograms, in 2SK-1 and 2SKD-1 wells of Salman gas field show strong astronomical signals of the Milankovitch cycles (E, e, O, P). After investigating the cyclostratigraphy of the upper part of the Zakeen Formation in the studied wells, by using new methods of evolutionary correlation coefficient and evolutionary significance levels, comparison of sediment accumulation rate variations of the Zakeen Formation was performed in the studied wells. Keywords: Cyclostratigraphy, Sediment accumulation rate, Milankovitch cycles, Zakeen Formation, Salman gas field Introduction The Zakeen Formation is a clastic succession and in its type section at Faraghan Mountains, north Bandar-Abbas, has 285 m thickness. It is composed of sandstones, shales, and with several dolostones horizons (Ghavidel-Syooki 1999). The Zakeen Formation, based on palynological studies by Ghavidel-Syooki (1999 & 2003), is attributed to the early to late Devonian (Lochkuvian to Frasnian). In this study, only the Frasnian sequence of the upper part of the Zakeen Formation in 2SK-1 and 2SKD-1 wells of the Salman gas field was studied. Cyclostratigraphic studies were also focused primarily on proving the existence of Milankovitch cycles in sedimentary sequences, determining timelines, calculating sediment accumulation rates and stratigraphic classifications (Zheng & Luo 2004; Li et al. 2018a; Chen et al. 2019). To compare the sediment accumulation rates of the upper part of the Zakeen Formation in the studied wells, cyclostratigraphy study was first performed to show the existence of the Milankovitch cycles and the way they affect the upper part of the Zakeen Formation. The spectral analysis methods together with density and spectral gamma-ray logs data were used to study the cyclostratigraphy of the studied formation. Milankovitch (Serbian scientist) has calculated the duration of the three main parameters of the Earth's orbit around the sun that affect global climate change, known as eccentricity, obliquity, and precession, and these are referred to Milankovitch cycles (Milankovitch 1941; Fletcher 2013). Cyclostratigraphy of the Devonian system in the different parts of Earth including southern China (Gong et al. 2001; Chen & Tucker 2003; De Vleeschouwer et al. 2017), France, Morocco (Ellwood et al. 2011), Canada (De Vleeschouwer et al. 2012; De Vleeschouwer et al. 2017), Poland (De Vleeschouwer et al. 2013, 2017), Belgium (De Vleeschouwer et al. 2014, 2017), USA (De Vleeschouwer et al. 2017; Pas et al. 2018) and varying frequencies of Milankovitch cycles from the deposits of these areas have been reported. The purpose of this study is to analyze cyclostratigraphy and compare the sediment accumulation rates of the upper part of the Zakeen Formation in 2SK-1 and 2SKD-1 wells of the Salman gas field. Material & Methods In this paper, by using evolutionary spectral analysis techniques (FFT spectrogram and WT scalogram) and MTM periodogram in a series of digital signal processing methods in Acycle v2.0 software (Li et al. 2018a), time series were extracted from SGR and RHOB logs. Afterward, their spectral powers were used in the cyclostratigraphic analysis of the upper part of the Zakeen Formation. Milankovitch cycles recorded in the upper part of Zakeen Formation were identified using a set of evolutionary spectral analysis methods for the desired logs including MTM and subsequently analyzed in the FFT Spectrogram (Kodama and Hinnov 2015). The influence of such cycles on sedimentation of the upper part of the Zakeen Formation and their abundance in this formation at different depths from the two studied wells were studied. The WT scalogram is then used to compare statistically significant zones between time series (Grinsted et al. 2004). The frequency ratio method (Mayer & Appel 1999) was used to establish the link between the cycles identified in the sedimentary signals and the theoretical astronomical parameters. After identifying the Milankovitch cycles in MTM periodograms, they were then extracted from the SGR logs by filtering the cycles of 405 kyr (E), 100 kyr (e), 34.4 kyr (O) and 21.3 kyr (P). Subsequently, confidence levels with median, 90, 95, 99% levels were plotted for each MTM periodogram and almost all cycles were sampled from the median confidence level and some above 90%. Through performing MTM periodograms, Milankovitch cycles were detected. Also, by using FFT spectrograms (reviewed by Hinnov), their influence on deposition of the upper part of Zakeen Formation and their abundance were labeled. Through the extraction of WT scalograms, high statistical significance zones were compared (correlation against E, e, O, and P cycle filters) to find the main lithological changes, probabilistically. Finally, cyclostratigraphic results in two studied wells were investigated. Moreover, sediment accumulation rates of the upper part of the Zakeen Formation in two studied wells (2SK-1 and 2SKD-1) were estimated. Through applying evolutionary correlation coefficients and evolutionary significance levels of spectral analysis methods for the SGR logs in both wells, estimates of sediment accumulation rates of the upper part of Zakeen Formation was precisely carried out. Discussion of Results & Conclusions Through plotted MTM periodograms for each well logs, the cycles ratio were identified in well 2SK-1 based on SGR MTM periodogram as 18.03, 5.63, 3.6, 2.39, 2.08, 1.58, 1.2, while with refer to RHOB MTM periodogram they are 20.8, 7.11, 4.0, 2.33, 2.0, 1.48, 1.33. This is close to the ratio of 20:5:2:1 cycles (from left to right we have the component ratio of the cycles E, e, O, and P). In contrast, in the MTM periodogram plotted for the SGR log, the ratios are 18.24, 6.08, 3.78, 2.87, 2.38, 1.55, while in MTM periodogram plotted for the RHOB log, ratios of 19.38, 6.45, 4.43, 3.6, 2.62, 2.16, 1.83, 1.49 were obtained. All ratios in two wells, being approximately equal to 20:5:2:1 and thus the relative ratios, each based on their value, are interpreted as one of the Milankovitch cycles (E or e or O or P). In this study, by evolutionary spectral analysis methods including MTM periodograms, FFT spectrograms, and WT scalograms, cyclostratigraphy study of the upper part of the Zakeen Formation were performed in 2SK-1 and 2SKD-1 wells of Salman gas field. Evaluation of sediment accumulation rates of the upper part of Zakeen Formation in these two wells was performed with evolutionary correlation coefficients and evolutionary significance levels. This allows them to be observed in the stratigraphic domain alongside the well log data. Based on FFT spectrograms in 2SK-1 well, three cycles including E, e and O have more effect on the sedimentation rate of the upper part of the Zakeen Formation. In 2SKD-1 well such an effect is due to four cycles comprising of E, e, O and P. Subsequent analyses by the evolutionary correlation coefficient spectrogram plotted for the SGR log in 2SK-1 well revealed that only the E cycle affected the deposition of the upper part of the Zakeen Formation. The evolutionary correlation coefficient plotted for SGR log in 2SKD-1 well also confirmed the effect of E and O cycles on the deposition of Zakeen Formation. Other cycles with low impact on cyclic sedimentation of the upper part of the Zakeen Formation have been involved in these two wells. Sediment accumulation rates of the upper part of Zakeen Formation were estimated by time columns from cyclostratigraphy and thickness of the upper part of the Zakeen Formation for both wells by approximately 0.8 cm per thousand years. Subsequently, through the analysis of evolutionary correlation coefficients plotted for SGR logs, it was determined that sediment accumulation rates of the upper part of the Zakeen Formation in 2SK-1 wells show ascending, constant and descending trends. In contrast, in the 2SKD-1 well, sediment accumulation rates have been almost constant. In general, the sediment accumulation rates of the upper part of Zakeen Formation in 2SK-1 well are estimated more compared to 2SKD-1 well. Also, large variations in sediment accumulation rates of the upper part of the Zakeen Formation were observed in the 2SK-1 well compared to the 2SKD-1 well, indicating the occurrence of hidden effective processes for these changes.

The Miocene aged Shanwang Formation from the Shanwang National Geopark in China represents a succession of lacustrine diatomaceous shales containing an abundant and diverse biota with lagerstätte fossilization of soft tissues. To date, the Shanwang Formation has not been investigated for cyclostratigraphy nor has it been dated with high precision methods. Now we use thorium data as a paleoenvironmental and paleoclimatic proxy to conduct a detailed cyclostratigraphic analysis. A new and simple cyclostratigraphic method, Wavelet Scale Series Analysis (WSSA) is developed to recognize Milankovitch cycles. A total of three short eccentricity and fifteen precession cycles are identified; obliquity cycles are not apparent. In the sedimentary succession, the corresponding precession and short eccentricity cycles are 1.17 m and 4.98 m thick respectively, with this verified by Correlation Coefficient (COCO) analysis and Multitaper-Method (MTM) spectral analysis. We estimate the studied interval was deposited over a duration of 0.3 Myr with a depositional rate of c. 5.7 cm/kyr. Paleomagnetic and radio isotope dating data shows that the diatomaceous shale was deposited during Chron C5En, which places it at approximately 18.5 Ma during the Burdigalian stage of the Early Miocene, rather than in the Middle Miocene as previously thought. The Shanwang lagerstätte biota therefore predates the Middle Miocene Climate Optimum (MMCO) and did not form within it. The geological time scale with a high resolution of 20 kyr was set accordingly. [ABSTRACT FROM AUTHOR]

• First sub-orbital scale hydrological record of PETM in East Asia. • Eccentricity forcing coincides with multi-phased precipitation variability. • Precession and half-precession cycles control precipitation intensity. • Orbital forcing of low-latitude insolation develops in East Asia during the PETM. The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) was an abrupt global warming event linked to massive carbon release into the ocean-atmosphere system. As such, it is considered a potentially useful analogue for present and future climate change. Consequently, deciphering its impact on the hydroclimate is important for predicting future changes under high p CO 2 and temperature conditions, especially in East Asia where more than a quarter of the world's population lives. Here, we use magnetic and geochemical data obtained through a thick lacustrine record of the PETM from China to demonstrate a large-scale increase in weathering and precipitation coeval with the PETM. Moreover, we show that precipitation variations through the PETM were strongly controlled by eccentricity, precession and half-precession climate cycles. Our results show that orbital forcing of low-latitude insolation played a key role in driving hydroclimate fluctuations and multi-phase changes in precipitation during the PETM, emphasizing the sensitivity of East Asian hydroclimate to subtle changes in insolation under conditions of high temperature and p CO 2 , perhaps similar to those expected in the future. [ABSTRACT FROM AUTHOR]

With the further exploration and development of shale oil and gas, cycle division of fine-grained sedimentary rock strata has been increasingly highly focused on by scholars. Owing to the application of the theory of classical sequence stratigraphy based on water depth changes and its technical methods being unsatisfactory in the isochronous division and correlation of deep-water fine-grained sedimentary strata, the cycle division of fine-grained sedimentary rock strata has always been a difficult point in the study of sequence stratigraphy. In this paper, the Milankovitch cycle recorded from the study interval and the environment response characteristics were studied, with the lacustrine shale in the lower third submember of the Paleogene Shahejie Formation (lower Es3 submember) in Well Fanye-1 of the Dongying sag, Bohai Bay Basin, as the object of study, by such technical means as thin section identification and X-ray whole rock diffraction, based on such data as logging data and geochemistry, combining the methods of spectral analysis, wavelet transform, and modulus extremum. The results showed that the stratigraphic cycle thicknesses caused by long eccentricity, short eccentricity, and obliquity periods were 38.95 m, 12.98 m, and 4.10 m, respectively, and a total of 16 short eccentricity periods and 4.5 long eccentricity periods were identified in the study interval. Thus, it was further calculated that the sedimentation time was approximately 1.905 Ma, and the average sedimentation rate was estimated to be 0.105 m/ka. Studies have shown that the sedimentary environment of lacustrine fine-grained sedimentary rocks is controlled by the astronomical period, based on which the climate as a whole changes from relatively dry and cold to warm and wet when the eccentricity increases. The identification of the Milankovitch cycle of the lacustrine fine-grained sedimentary strata will provide references for the study of high frequency sequence and the division of high-resolution sequence strata, which can effectively solve the scientifically difficult isochronous division and correlation of lacustrine shale strata. [ABSTRACT FROM AUTHOR]

A detailed biostratigraphic, chemostratigraphic, and chronostratigraphic study was carried out in the South‐Western margin of the Neo‐Tethys ocean (Tunisia) covering the Eocene‐Oligocene interval to report potential paleoenvironmental and paleoclimatic changes associated with the growth of the Antarctic ice sheet (AIS). The studied section consists of marls and limestones extending from the Helicosphaera compacta nannofossil Zone (CNE21) to the Reticulofenestra umbilicus Zone (CNO2). The Bc of Clausicoccus subdistichus coincides in northeastern Tunisia with the extinction of hantkeninids and is thus used here to define the Eocene/Oligocene boundary (EOB) at 34.03 Ma. Calcareous nannofossil assemblages suggest a significant change from oligotrophic/warm surface waters during the late Eocene to eutrophic/cool waters during the early Oligocene. The observed changes in trophic conditions are synchronous with a shallowing trend testified by an increase in nearshore species and enhanced terrigenous input. Major environmental changes occurred at the EOB and across glaciation event Oi‐1a whereas we record a poor imprint of glaciation event Oi‐1. Three orbital configurations have been distinguished: (1) The late Eocene is characterized by a prominent 405‐kyr cycle and a weak obliquity component; (2) the onset of cooling at 34.35 Ma coincides with the rosette‐shaped discoaster extinction and is reflected by a shift toward enhanced obliquity and short‐eccentricity cycles. The installation of a fully developed AIS (event Oi‐1a, 32.75 Ma) shows the most pronounced obliquity imprint reflecting an increased influence of high‐latitude climate processes; (3) after 31.75 Ma, the obliquity decreases in coincidence with the return to a dominant long‐eccentricity cycle. Plain Language Summary: The Eocene/Oligocene transition corresponds to one of the most important climatic shifts in the Cenozoic. This paleoclimatic shift from the greenhouse of the late Eocene to the icehouse regime in the early Oligocene triggered changes in the paleoenvironmental conditions of the Neo‐Tethyan area. We used calcareous nannofossil assemblages, carbon isotopes, elemental data (X‐ray fluorescence), and spectral analysis applied on magnetic susceptibility to report the possible effects of ice volume changes associated with the Antarctic glaciation on the Southern Neo‐Tethyan region and on the expression of Milankovitch cycles at low latitudes. We observe a change in the calcareous nannofossil assemblages that suggests a transition from low‐nutrient/warm‐water conditions to more heterotrophic/cooler conditions across the Eocene/Oligocene interval associated with the shift from a dominant 405‐kyr long‐eccentricity cycles to a prevalent obliquity and short‐eccentricity forcing. However, the situation shifted again at 31.75 Myr, with the return of dominant long‐eccentricity cycles. Key Points: High phytoplankton productivity across the EOT of the Southern Neo‐Tethys (Tunisia)Astronomical calibration of the Tunisian record and power variations in the expression of distinct orbital components across the EOTMajor changes in trophic conditions and sediment composition at the EOB and across Oi‐1a but minor changes across the main Oi‐1 glaciation [ABSTRACT FROM AUTHOR]

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Cyclostratigraphy claims to rely on an accurate astronomical time scale and further on a clear imprint it supposedly makes on the sedimentary record. Grounded upon the Milankovitch theory, geologists first sought to apply this method to develop a timescale for Quaternary glacial/interglacial oscillations. But there are several glaring unresolved problems with this approach. Although solar radiation measurements at high latitude appear to lend support to the mechanism, the data are carefully selected, typically restricted to the summer solstice or the months of June or July. By contrast, the larger dataset for the warm half-year for the whole hemisphere shows the Milankovitch effect is very small. Moreover, geologists believe glacial episodes over the past 900,000 years have been controlled by the 100,000-year eccentricity cycle, but that cycle has a very small effect relative to other cycles. Further, glacial cycles should be out of phase between the hemispheres, yet they are not. Finally, proponents rely on correlation between Milankovitch cycles and deep-sea cores, but these appear to be the result of circular reasoning and the reinforcement syndrome. [ABSTRACT FROM AUTHOR]

The shale lithofacies shows obvious heterogeneity during the Late Ordovician-Early Silurian in the Upper Yangtze area, SW China. To elucidate the Wufeng-Longmaxi shale lithofacies' formation mechanism, we conducted high-resolution cyclostratigraphic analysis and geochemical studies of the W2 well. The findings indicate significant disparities in the sedimentation rates of the Wufeng-Longmaxi Formations, with both units recording the ∼1.2-Myr-long obliquity cycles and the ∼405-kyr-long eccentricity cycles period. Notably, the ∼1.2-Myr-long obliquity cycles predominantly influenced sea-level fluctuations by mediating latitudinal heat distribution between high and low latitudes during the Late Ordovician-Early Silurian. Additionally, leveraging the sedimentary noise model and core log data, we identified five distinct sequences (SQ1∼SQ5) based on reconstructed sea-level fluctuations. During the transgressive system tract (TST1) of SQ1, siliceous shale lithofacies association (S) was prominently developed. In the subsequent highstand systems tract (HST1) of SQ1, shifts in the depositional environment facilitated the enhanced development of calcareous shale lithofacies association (C). During the SQ2 period, the swift elevation of sea-levels facilitated the pronounced proliferation of siliceous shale lithofacies association (S). During the SQ3 and SQ4 period, lower sea-levels coupled with significant terrigenous contributions resulted in the well-developed mixed shale lithofacies association (M). Throughout the SQ5 period, intensified bottom currents and substantial clay material deposition favored the development of the argillaceous shale lithofacies association (CM) developed as the predominant lithofacies. Ultimately, our research reveals that the heterogeneity of shale lithofacies is a multifaceted response to a series of changes in the paleoredox environment, paleoproductivity levels, and terrigenous influx, all driven by sea-level fluctuations forced by astronomical orbits. Paleoredox conditions dictate biosilica's degradation and preservation, influencing sediment composition. Paleontogenic types and productivity levels set the sediment's mineral composition. Meanwhile, terrigenous input crucially impacts the accumulation of clay and clastic materials in the sediment. • Division of marine shale sequences using sedimentary noise model. • The ∼1.2-Myr-long obliquity cycles drive the glacial eustasy changes in the Upper Yangtze area. • Eustatic changes driven by Milankovitch cycles is the key for formation of shale lithofacies. • Sea-level changes control shale lithofacies development patterns. [ABSTRACT FROM AUTHOR]