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A high-precision geologic time scale is the essential key for understanding the Earth’s evolutionary history and geologic processes. Astronomical tuning of orbitally forced stratigraphic records to construct high-resolution Astronomical Time Scales (ATS) has led to a progressive refinement of the geologic time scale over the past two decades. In turn, these studies provide new insights regarding the durations and rates of major Earth events, evolutionary processes, and climate changes, all of which provide a scientific basis for contextualizing and predicting future global change trends. South China hosts some of the best-exposed and well-dated Neoproterozoic through Mesozoic stratigraphic sections in the world; many of which are suitable for cyclostratigraphy and calibrating the geologic time scale. In North China, several Cenozoic oil-bearing basins have deep boreholes with continuous sampling and/or well logging that enable derivation of astronomically tuned time scales for an improved understanding of basin evolution and hydrocarbon generation. This Special Issue focuses on case studies of astrochronology and applied cyclostratigraphy research using reference sections within China. In this introductory overview, we: (1) summarize all existing astrochronology studies of the Neoproterozoic through Cenozoic sections within China that have been used to enhance the international geologic time scale, (2) examine briefly the astronomically forced paleoclimate information recorded in various depositional systems and the modern techniques employed to analyze the periodicity of these signals encoded within the sedimentary record, and (3) summarize the 20 contributions to this Special Issue of Palaeogeography, Palaeoclimatology, Palaeoecology on 'Cyclostratigraphy and Astrochronology: Case studies from China’.

This paper presents a late Holocene chironomid-inferred record of July air temperature from a core obtained from Lake Uddelermeer in the Netherlands. The core interval, which dates from 2500 to 400 cal. yr. BP, was analysed at multi-decadal resolution for organic content, pollen, spores and NPPs (Non Pollen Palynomorphs), and chironomid head capsules. These proxies indicate that, from 2500 to 1140 cal. yr. BP, the lake was mesotrophic and sustained a Littorellion community, while the chironomid assemblage was dominated by littoral species associated with macrophytes. At 1140 cal. yr. BP, a shift in the lake ecology occurred from low-nutrient to high-nutrient conditions dominated by algae. This shift might be linked to a concurrent increase in human impact and is reflected in the chironomid assemblage by increases in eurytopic taxa, which are resistant to disturbances. Shifts in the chironomid record between 2500 and 1140 cal. yr. BP do not coincide with changes in lake ecology and are presumably driven by climate change. Using a Norwegian-Swiss calibration dataset as a modern analogue, we produced a chironomid-inferred temperature (C-IT) reconstruction. This reconstruction compares well to other regional temperature reconstructions in timing and duration showing a Roman Warm Period between 2240 and 1760 cal. yr. BP, a Dark Age Cold Period starting at 1760 cal. yr. BP and the Medieval Climate Anomaly beginning at 1280 cal. yr. BP. The C-IT record indicates a temperature drop of 1.5 °C from the Roman Warm Period to the Dark Age Cold Period. Findings improve knowledge of the first millennium AD in NW Europe, which was characterised by changes in landscape, vegetation, society and climate.

This paper reviews quantitative biostratigraphic data from 101 petroleum exploration wells from the Malay, Sarawak and Sabah basins, and places the stratigraphy of each area into a precise chronostratigraphic framework comprising 41 transgressive-regressive depositional packages which are fully defined here. Each package is ‘fingerprinted’ by foraminiferal, nannofossil and palynological index fossils, and then tied to the global pattern of glacio-eustatic sea level and climate changes based on the global δ18O and δ13C datasets used to calibrate the geological timescale. The result is a tightly constrained chronostratigraphic framework that is applicable from deep to shallow water and is of high accuracy. It is concluded that there is a sedimentation ‘pulsebeat’ across Southeast Asia, independent of local and regional tectonics, driven by patterns of global climate change. For the Oligocene and Miocene, Antarctic glaciation is the key driver, whereas the Pliocene cycles are mainly driven by the expansion and contraction of Northern Hemisphere glaciers. The new chronostratigraphic framework allows unconformities across Malaysia to be better characterised, and the different classification schemes of seismic “Groups” in Malay and Penyu basins, “Cycles” in offshore Sarawak and “Stages” in offshore western Sabah to be correlated. Also, with a clear understanding of the effect of fluctuating sea levels on the stratigraphy of the region, it is easier to make firm judgments regarding the effect of tectonics. The study also characterises systems tracts from shelf to basin floor using biostatigraphic assemblages, which should help in ground-truthing the architecture of depositional sequences in the region based on seismic. The new framework is proposed as an alternative to the outdated TB scheme of Haq et al. (1988) , widely used to interpret depositional cycles across Sarawak and Sabah.

International audience; This paper presents the first continuous pollen record from the southern Namib Desert spanning the last 50,000 years. Obtained from rock hyrax middens found near the town of Pella, South Africa, these data are used to reconstruct vegetation change and quantitative estimates of temperature and aridity. Results indicate that the last glacial period was characterised by increased water availability at the site relative to the Holocene. Changes in temperature and potential evapotranspiration appear to have played a significant role in determining the hydrologic balance. The record can be considered in two sections: 1) the last glacial period, when low temperatures favoured the development of more mesic Nama-Karoo vegetation at the site, with periods of increased humidity concurrent with increased coastal upwelling, both responding to lower global/regional temperatures; and 2) the Holocene, during which time high temperatures and potential evapotranspiration resulted in increased aridity and an expansion of the Desert Biome. During this latter period, increases in upwelling intensity created drier conditions at the site. Considered in the context of discussions of forcing mechanisms of regional climate change and environmental dynamics, the results from Pella stand in clear contrast with many inferences of terrestrial environmental change derived from regional marine records. Observations of a strong precessional signal and interpretations of increased humidity during phases of high local summer insolation in the marine records are not consistent with the data from Pella. Similarly, while high percentages of Restionaceae pollen has been observed in marine sediments during the last glacial period, they do not exceed 1% of the assemblage from Pella, indicating that no significant expansion of the Fynbos Biome has occurred during the last 50,000 years. These findings pose interesting questions regarding the nature of environmental change in southwestern Africa, and the significance of the diverse records that have been obtained from the region.

The Last Interglacial Period (LIP) is often regarded as a good analogue for potential climatic conditions under predicted global warming scenarios. Despite this, there is still debate over the nature, duration and frequency of climatic changes during this period. One particularly contentious issue has been the apparent evidence of climatic instability identified in many marine cores but seemingly lacking from many terrestrial archives, especially within the Arctic, a key region for global climate change research. In this paper, geochemical records from Lake El'gygytgyn, north-eastern Russia, are used to infer past climatic changes during the LIP from within the high Arctic. With a sampling resolution of ~ 20–~ 90 years, these records offer the potential for detailed, high-resolution palaeoclimate reconstruction. This study shows that the LIP commenced in central Chukotka ~ 129 thousand years ago (ka), with the warmest climatic conditions occurring between ~ 128 and 127 ka before being interrupted by a short-lived cold reversal. Mild climatic conditions then persisted until ~ 122 ka when a marked reduction in the sedimentation rate suggests a decrease in precipitation. A further climatic deterioration at ~ 118 ka marks the return to glacial conditions. This study highlights the value of incorporating several geochemical proxies when inferring past climatic conditions, thus providing the potential to identify signals related to environmental change within the catchment. We also demonstrate the importance of considering how changes in sedimentation rate influence proxy records, in order to develop robust palaeoenvironmental reconstructions.

article i nfo In South America, the arid and semiarid subtropical regions through the Atacama Desert and north-central Chile between 19° and 32°S are currently a gap in the tree-ring chronology network. Only a short tree-ring chronology has been published for this vast region and little is known about the suitability of many woody species for tree-ring analysis and dendroclimatology. In this paper we present the first detailed analysis of the climate responses and influences of the El Nino-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) on the tree-rings of three species new to dendrochronology and that typically occur at high elevations in the Andes of central and north-central Chile. Three well-replicated tree-ring chronologies of Kageneckia angustifolia, Proustia cuneifolia and Fabiana imbricata are compared with century-long regional records of precipitation and temperature, and with the N3.4 SSTand PDO indices in both time and frequency- domains using correlation and wavelet analysis. The radial growth of these species is controlled by winter precipitation and is also positively correlated with temperature during most of the rainy season from April to September (autumn-spring). The regional climate as well as tree growth is strongly modulated by ENSO and ENSO-like conditions in the equatorial Pacific at both interannual and interdecadal timescales. The decadal and interdecadal variability is not correlated with PDO and appears to be related to the Interdecadal Pacific Oscillation (IPO), a Pacific-wide ENSO-like mode of climate variability. Despite their relatively short lifespans, these three new species have a high potential for dendrochronological and dendroclimatic studies in the semiarid region of Chile over the last two centuries.

This paper reports the pollen analysis of an 8 m core from a mire at 445 m altitude and 2°S latitude on ultramafic soils near the western shore of Lake Matano, South Sulawesi. The area is almost undisturbed by humans and the record is believed to cover about 50–75,000 yr B.P., with some breaks in the record. A section from 17,000 to around 5500 yr B.P. and the last 1000 years of the record may be missing or disturbed. The results show that montane forest grew around the site continuously through the late Pleistocene with a maximum increase in higher altitude taxa from 35,000 to after 17,000 yr B.P., the time of glacial maxima elsewhere. Also in this period, increases in grass and Casuarina indicate possible drier conditions. The Holocene sections record lower altitude forest with increased taxonomic diversity, including secondary species. The results show that vegetation in the region has been sensitive to climatic change, the Pleistocene ecology being consistent with a temperature change of about 2.5–3.5°C with a phase up to 50% drier than present. The site climate was possibly affected by shelf exposure in the Gulf of Bone due to lower sea levels. However the tropical forest demonstrates overall long term stability in which changes in dominance may reflect minor shifts in disturbance and tree longevity. A distinctive record of fine charcoal occurs throughout the deposit. This shows that the forest has never been continuously fire-free for a very long time. The cause of the fires may be natural as no evidence for human occupation was discerned.