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According to modern atmospheric circulation models, the Intertropical Convergence Zone (ITCZ), as the Earth's meteorological equator, plays an essential role in the low-latitude hydrologic cycles. The limited availability of high-resolution tropical climate archives, especially from the Early Paleozoic Era, severely limits our understanding of ITCZ migration dynamics in deep time. Here we present high-resolution climate-proxy records (i.e., magnetic susceptibility (MS) and Zirconium/Aluminum (Zr/Al)) from tropical marine sediments of the ∼526-million-year-old Qiongzhusi Formation in South China to investigate the link between orbitally forced insolation changes, ITCZ migration dynamics, and low-latitude climate processes. These orbital-scale variations in MS and Zr/Al series are interpreted as alternations between wet and dry cycles, controlled by monsoon intensity under the orbitally forced ITCZ-related paleo-Hadley Cell dynamics. Our results show that combined precession and obliquity orbital cycles had an impact on the Early Cambrian ITCZ migration. Specifically, the precession and obliquity forcing shift the mean position of the ITCZ latitudinally by changing the interhemispheric pressure contrasts, thus affecting the low latitude hydroclimate cycle. We report semi-precession cycles of 8.3–7.9 kyr, which were probably associated with the twice-annual passage of the ITCZ across the intertropical zone, consistent with the paleogeographical location of South China near the equator during the Early Cambrian. Observed ∼1.1 – ∼1.5 Myr eccentricity amplitude modulation (AM) cycles and ∼ 1.0 – ∼1.2 Myr obliquity AM cycles may provide geological evidence for the chaotic motion between Earth and Mars in the Early Cambrian. • Combined precession and obliquity cycles regulated the Early Cambrian ITCZ migration. • We report the semi-precession cycles of 7.9–8.3 kyr in the Early Cambrian. • Our study provides geological evidence for the chaotic Solar System in the Early Cambrian. [ABSTRACT FROM AUTHOR]

• We develop a 10.8-Myr astronomical time scale for the Early Cambrian Stage 2-Stage 3. • ∼1.5-Myr obliquity cycles significantly affect sea-level oscillations in the greenhouse period. • New chaotic resonance of Mars-Earth system may occur in the Early Cambrian Period. • Constraints on the Earth-Moon system evolution in deep time are refined. The early Cambrian was a critical period of Earth history, marked by explosive diversification of metazoans and several profound changes in Earth's surface environments and global climate. A valid temporal framework for the early Cambrian Period and across the major bio-events is poorly constrained, and the key underlying forcings of million-year (Myr) scale sea-level variations in a greenhouse lacking polar ice sheets are still disputed. Here, the high-resolution gamma-ray logs (GR) and Fe/Al records are utilized to conduct cyclostratigraphic analysis of the early Cambrian Stage 2-Stage 3 Qiongzhusi Formation of the Well A borehole in South China. A ∼10.8 Myr-long high-resolution astronomical time scale across Stage 2-Stage 3 is developed by astronomical tuning of gamma-ray logs and Fe/Al series to the stable 405-kyr long-eccentricity cycles. The Myr-scale sea-level fluctuations in the early Cambrian greenhouse are reconstructed through the sedimentary noise modeling of the 405-tuned GR series and agree with sequence stratigraphic interpretations, lithofacies stacking patterns, and depositional environment changes. The antiphase correlation of filtered ∼1.5 Myr cycles of sedimentary noise curves with the ∼1.5 Myr obliquity modulation cycles demonstrates that the variations in land-ocean water exchange linked to changes in poleward moisture and heat transport dominated by ∼1.5 Myr obliquity modulation cycles may be a primary driver for eustasy during non-glacial early Cambrian period. A new resonance state in the early Cambrian Stage 2-Stage 3, manifested by ∼1.5 Myr eccentricity: ∼1.5 Myr obliquity, could be mainly associated with the Earth-Mars secular resonance and constrain the chaotic evolution of the Solar System in deep time. Two independent approaches are employed to reconstruct the history of Earth-Moon system characteristics, including the precession constant, the Earth-Moon distance and the day length. Our results enhance knowledge of the connection of Myr-scale sea-level variations to astronomically induced climate change under greenhouse climate and provide new empirical constraints on the chaotic motion of the Solar System and the evolution of the Earth-Moon System in deep time. [ABSTRACT FROM AUTHOR]

The Ediacaran-Cambrian transition was a critical period of Earth history because of the coincidence among climate change, bioevolution, and tectonic activity. The nature of carbon and sulfur-cycling processes spanning the Ediacaran-Cambrian boundary remains debatable. This study considers high-resolution stable isotope chemostratigraphy of the Sugetbrak and Yutixi sections of the Keping area of the Tarim Basin, northwestern China. The sections display a pronounced negative δ13C carb shift (the Basal Cambrian Carbon Isotope Excursion) that spans the Ediacaran-Cambrian boundary. Deposits overlying the negative excursion are characterized by heavier δ13C carb values ranging from −7.8‰ to +4.1‰. The biostratigraphically calibrated δ13C carb profiles likely reflect widespread perturbation of the global oceanic carbon cycle and associated mass extinction and subsequent biological evolution. The δ34S py profiles of the studied sections display a wide distribution of values, ranging from −16.4‰ to 23.8‰. The variable δ34S py signatures of these sections are partially controlled by microbial sulfate reduction rates, which are sensitive to local sulfate concentration, availability of organic matter and the marine redox state. The strong coupling between enhanced organic carbon and pyrite burial, the appearance of Cambrian-type animals and a shift to a more oxidizing marine environment might suggest a temporal causality of higher oxygen levels of the atmosphere-ocean realm with bio-events during the Ediacaran–Cambrian transition. The development of ecosystems across the Ediacaran–Cambrian transition may have significantly impacted the oceanic carbon and sulfur biogeochemical processes in Earth's history and, in turn, affecting themselves. • Negative δ13C carb excursions (Cn1 and Cn2) can be traced in the sections. • The pronounced negative δ13C carb shift (Cn1) can be traced globally. • Cn1 may reflect widespread perturbation of the global oceanic carbon cycle. • The δ34S py are partially controlled by microbial sulfate reduction rates. [ABSTRACT FROM AUTHOR]

The astrochronology for the Early Triassic has been constructed from well-preserved marine successions; however, astronomical analyses of terrestrial strata have continued to be rare and problematic. Physical logs (natural gamma ray logging data) from two wells in the Junggar Basin, northwestern China cover the entire Lower Triassic terrestrial Baikouquan Formation and have been shown to be a powerful tool in cycle analysis. Therefore, these logs offer an excellent opportunity to detect astronomically forced sedimentation in a terrestrial setting from mid to high latitudes. Power spectral analysis revealed that the sedimentary cycles had wavelengths of 31.3–35.9 m, 8.4–10.0 m, 4.0–4.6 m, and ~4.0 m. These are interpreted to correspond to the orbital eccentricity cycles of 405 kyr and ~100 kyr and to the obliquity cycles of ~51 kyr and ~34 kyr, respectively. We, thus, established an astronomical time scale for the studied interval, assuming that the 31.3–35.9 m cycles represent the 405 kyr eccentricity cycles. This astrochronology indicated that the duration of the Baikouquan Formation was 2.0 ± 0.1 Myr. Statistical evaluations of optimal sediment accumulation rates using the correlation coefficient approach showed that the rates of the investigated successions were approximately 6.0–12.0 cm/kyr. Orbitally controlled climate change was the major dynamic mechanism for the formation of Early Triassic fan delta successions in the Junggar Basin. • Astronomical forcing controlled the Early Triassic fan delta deposition • Astrochronology indicates a 2.0 ± 0.1 Myr duration of the Baikouquan Fm. • Mesozoic fan-delta succession responds to orbitally controlled climate change. [ABSTRACT FROM AUTHOR]

[Display omitted] • The source areas of the sediments experienced weak to medium chemical weathering. • Elemental diagrams indicate that the shales were primarily from igneous rocks. • Sediments in the southeast part were sourced in the tectonically active Dianqian and Xuefeng Uplifts. • Sediments of the northwest area were transported from the passive margin setting. Organic-rich shales of the Lower Silurian Longmaxi Formation have produced commercial amounts of natural gas. The nature of the paleoclimate and tectonic setting of the provenance region from which these deposits were derived remains the topic of debate. This paper describes the results of a multi-faceted geochemical investigation of 46 samples of the Longmaxi Formation of the Upper Yangtze Platform. Chemical Index of Alteration (CIA) values of the analyzed samples indicate that parent rock experienced relatively weak to medium chemical weathering prior to deposition. Th/Sc, and Zr/Sc ratios suggest that the sediment shed from the provenance area experienced three kinds of different recycling and sorting trend. Variations of Index of Compositional Variability (ICV) and K 2 O/Al 2 O 3 ratios suggest that the sediment source shifted over paleogeographic locations. The Al 2 O 3 -(CaO*+Na 2 O)-K 2 O triangular diagram, Th/Sc and Th/Yb ratios, and Al 2 O 3 -TiO 2 , TiO 2 -Zr, and La/Th-Hf bivariate diagrams suggest that the sediment was primarily derived from felsic and intermediate igneous rocks. High- and low-silica multidimensional diagrams and discriminant function-based multidimensional diagrams indicate an active tectonic setting for the sediments in the south and east of the Upper Yangtze Platform and a passive continental margin setting for the sediments in the north part. Also they illustrate that the sediments in the central and west part were sourced in both an active tectonic setting and a passive continental margin. Variation of multiple geochemical proxies provide new insight into temporal and spatial variations of the provenance, climate, and tectonic setting from which sediment of the Longmaxi Formation were derived. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Whole herb of Lysimachia christinae has long been used as a remedy for cholelithiasis extensively in China. This study was aimed to validate the effect of L. christinae on eliminating preestablished cholesterol gallstone (CGS) in model animals. Materials and methods Acute toxicity of aqueous extract of L. christinae (LCAE) was estimated in male C57BL/6 mice, so was the efficiency of LCAE on preformed CGS induced by lithogenic diet. The effects of LCAE were also examined on bile secretion rate, the lipid profiles of bile and serum, body weight, main visceral organ indexes, and histomorphology of main visceral organs. Results Single dose of LCAE did not lead to death and changes on body weight gain, main visceral organ indexes, histomorphology of main visceral organs, and blood hemogram and biochemical indexes, even at dose of 50 g material/kg body weight. Preestablished CGSs were almost entirely eliminated after administration of LCAE for 2 wk at high dose or for 4 wk at low dose. LCAE promoted bile secretion and lowered cholesterol levels in either cystic bile or hepatic bile. LCAE also decreased serum cholesterol content, especially LDL-C content, tremendously, reduced the levels of serum HDL-C, phospholipid, and triglycerine a little, and lowered body weight and liver index significantly. After medication of LCAE for 8 wk , neither visceral indexes nor histomorphology of heart, kidney, and spleen were influenced, but fatty degeneration of liver induced by high fat and high cholesterol diet was reverted. Conclusion L. christinae can be considered as non-toxic. It showed prominent efficiency of eliminating preexisted CGS in mice and indicated a hypolipidaemic effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six types of the organic-rich shale laminae are reported in the Dongying Sag. • Discontinuous laminae were formed under high-energy hydrodynamic conditions. • Shale laminae containing favorable reservoir storage space are in the order of wavy laminar > lenticular laminar > weak laminar. • Thick and wavy laminae are the most favorable types for shale oil exploration. Shale oil exploration in China has demonstrated that laminated shales are favorable lithofacies for producing shale oil effectively. It is of great significance to study the type and reservoir properties of shales with different laminar structures. In this study, the laminae of Paleogene organic-rich shales in the Dongying Sag, Bohai Bay Basin were divided into two categories and six types based on thin section petrography, scanning electron microscopy (SEM), and geochemical characterization. The laminar types include thin parallel laminae, thick parallel laminae, wavy laminae, lenticular laminae, weak laminae, and sandy laminae. The first three types of laminae have good continuity and were formed under low-energy hydrodynamic conditions. In comparison, the latter three types are discontinuous and were formed under relatively high-energy hydrodynamic conditions with a strong terrigenous input. Significant differences were observed in the reservoir space types, microcracks, and oil-bearing properties among the different laminae. Analyses of porosity and oil saturation further revealed that laminated shales with high laminar continuity exhibit higher porosity, permeability, and oil saturation values than shales with poor laminar continuity. Shales with thick parallel laminar shale and wavy laminar shale possess favorable petrophysical parameters. Thus, from the perspectives of reservoir and oil-bearing properties, laminated shales with high laminar continuity are better than shales with poor laminar continuity for shale oil exploration in the Dongying Sag. The new findings provide a reference for the optimization and evaluation of favorable continental shale oil reservoirs in eastern China. [ABSTRACT FROM AUTHOR]