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In recent years, the evolution of the magnetic flux lobes in terms of location and intensity has been attributed to paleosecular variation of the geomagnetic field, reflecting outer‐core fluid convection close to the core‐mantle boundary. However, most results were based on observational data for the past 400 years supplemented by sparse archeomagnetic studies with data for approximately 3 kyr. In this paper, we construct a relative paleointensity (RPI) record and an inclination record spanning the past ∼90 kyr based on two cores from Tengchong Qinghai Lake (Yunnan Province, China), a closed crater lake that formed in the late Pleistocene. The evolution of flux lobes and the non‐dipole field can be assessed on a much longer time scale. Although the concentration and domain state of magnetic grains in the cores vary significantly, the RPI record is still representative of geomagnetic field features in the region of Yunnan Province, China. The contrasting trends in RPI with the records for eastern China since the late Holocene indicate the southeastward migration of the Siberian flux lobe. During the last glacial period, the RPI records of Tengchong Qinghai Lake and the North Atlantic Ocean show opposite trends, denoting the diverse and strong influence of the two flux lobe systems. The strong reverse flux lobe in the North Atlantic Ocean strengthened the non‐dipole field, while the weak normal flux lobe in Tengchong weakened the non‐dipole field. Plain Language Summary: Earth's magnetic field is composed of two main field components: a dipole field and a non‐dipole field. Although the non‐dipole field constitutes a minor component of the geomagnetic field, its variations in strength and location over different time scales have a significant influence on the surface expression of the geomagnetic field. The flux lobes arising from the fluid convection at the boundary between the core and mantle may produce the main components of the non‐dipole field. In recent years, the distribution of magnetic flux has been discussed based mainly on instrumental data and archeomagnetic data spanning a few kyr, which limits our understanding of flux lobe evolution on a much longer time scale. In this paper, we reconstruct a relative paleointensity (RPI) and an inclination records over the past ∼90 kyr from sediments of a closed volcanic lake in Tengchong, Yunnan Province, China. The results show that the RPI in the Tengchong area differs from the records for eastern China in the Holocene and from the records in the North Atlantic Ocean during the last glacial period. We conclude that a flux lobe may have played an important role in the non‐dipole field in the Tengchong and in the North Atlantic Ocean. Key Points: High‐resolution paleosecular variation records, including relative paleointensity (RPI) and inclination for the past 90 kyr, are derived from sediments in a closed lake in ChinaThe Holocene RPI trend obtained differs from records from records from eastern China, indicating the movement and intensification of the Siberian flux lobeThe opposing RPI patterns from the lake and the North Atlantic Ocean during the last glacial period indicate the influence of flux lobe systems on the non‐dipole field [ABSTRACT FROM AUTHOR]

The glacial trough is a common glacier erosion landscape, which plays an important role in the study of glacier erosion processes. In a sharp contrast with the developing river, which is generally meandering, the developing glacial trough is usually wide and straight. Is the straightness of the glacial trough just the special phenomenon of some areas or a universal feature? What controls the straightness of the glacial trough? Until now, these issues have not been studied yet. In this paper, we conduct systematic numerical models of the glacier erosion and simulate the erosion evolution process of the glacial trough. Numerical simulations show that: (1) while the meandering glacier is eroding deeper to form the U-shaped cross section, the glacier is eroding laterally. The erosion rate of the ice-facing slope is bigger than that of the back-slope. (2) The smaller (bigger) the slope is, the smaller (bigger) the glacier erosion intensity is. (3) The smaller (bigger) the ice discharge is, the smaller (bigger) the glacier erosion intensity is. In the glacier erosion process, the erosion rate of the ice-facing slope is always greater than that of the back-slope. Therefore, the glacial trough always develops into more straight form. This paper comes to the conclusion that the shape evolution of the glacial trough is controlled mainly by the erosion mechanism of the glacier. Thereby, the glacial trough prefers straight geometry. [ABSTRACT FROM AUTHOR]

Clues of climate change on the Alashan Plateau since the last glacial period (40 ka) are important for revealing the mechanism of desertification of middle-latitude deserts in the Northern Hemisphere (NH). Studies are still rare for the understanding of the specific relationship of climate changes between the Alashan Plateau and the global. Based on a systematic and comparative analysis of the existing research in China and the international academic community, this paper reviews the environmental evolution history of the Alashan Plateau since the last glacial period from the records of paleo-environment and geomorphological characteristics in different deserts of the plateau (e.g., Badanjilin, Tenggeli, and Wulanbuhe). From about 40 ka to the end of the last glacial maximum, the climate on the plateau was wetter than it is today, and to the end of the Pleistocene, the climate was generally dry and the aeolian activities were enhanced. However, the climate was arid during the whole last glacial period in the Wulanbuhe Desert, evidently different from the overall pattern of the plateau. The Tenggeli Desert was characterized by an arid climate in the early Holocene. The most controversial events for the Alashan Plateau are the drought events in the middle Holocene in the Badanjilin Desert. The role and impact of the westerlies and the East Asian Summer Monsoon (EASM) systems on the climate change of the desert and even the whole plateau is a vexed question that brings different views in different periods. There is still a lack of definite evidence representing the events of global environmental change that occurred on the plateau during the discussed period. The distinctive morphology of dune mountains and the distribution of sand dunes are mutually indicative of the direction and energy of wind systems on the plateau. It is suggested that appropriate wind energy is the significant key to the desertification in these middle-latitude deserts on the plateau. From a global-scale review of climate change, the desertification of the modern-scale sandy desert landscapes on the Alashan Plateau is generally related to the global glacial period and the cold and dry climate during the past 40 ka. [ABSTRACT FROM AUTHOR]

Understanding ancient climate changes is hampered by the inability to disentangle trends in continental ice volume from records of relative sea-level change. As a unique coastal deposit in tropical and subtropical regions, beachrock has been proved to be reliable for constraining the glacial meltwater signal and thus the total volume of land-based ice in Quaternary. However, beachrock is rarely recognized in the fossil record due to (a) the two-dimensional distribution of beach deposits, as opposed, for example, to extended platform sediments, and (b) the fact that specific environmental conditions are required in order to lithify sediments directly on the beach. By combining the stratigraphic architecture with petrography of characteristic carbonate cements, we demonstrate the first known occurrence of Ordovician beachrock in the Tarim Block, northwestern China. According to biostratigraphic data, a middle Katian (Upper Ordovician) palaeokarst surface is capped by carbonate conglomerate beachrock and this is suggesting a significant relative sea-level rise in late Katian. The beachrock can be correlated with widespread subaerial exposure surfaces and a pronounced stratigraphic gap within the Katian in northwestern Tarim. We suggest that the beachrock ‘fingerprinted’ a strong melt-water pulse in high latitudes after a short-lived Katian glaciation, which has not received much attention in scientific papers so far. [ABSTRACT FROM AUTHOR]

It is imperative to elucidate the process of evaporation in lakes, particularly those that are freshwater and are situated in middle and high latitudes. Based on one-year evaporation and high-frequency meteorological–water quality data of Lake Wuliangsuhai, this study analyzed the applicability and driving mechanism of the evaporation model. These dynamics are elucidated by the vorticity covariance method combined with the multivariate constrained evaporation Modelling method. The findings of this study revealed that (1) Lake evaporation (ET) is affected by multiple meteorological–water quality constraints, and the water quality indicators significantly related to ET are also affected by lake stratification. The coupled meteorological–water quality evaporation model can explain 93% of the evaporation change, which is 20% higher than the traditional meteorological Modelling evaporation model. (2) The nighttime ET is mainly affected by the thermal inertia lag, and the nighttime ET loss in Lake Wuliangsuhai accounts for 37.34% of the total evaporation, which cannot be ignored. (3) The actual water surface evaporation of the lake is much smaller than that measured by the pan conversion method and the regional empirical C formula method. The cumulative evaporation of Lake Wuliangsuhai from the non-freezing period to the early glacial period converted from meteorological station data is 1333.5 mm. The total evaporation in the non-freezing period is 2.77~3.68 × 108 m3, calculated by the lake area of 325 km2, while the evaporation calculated by the eddy station is 1.91 × 108 m3. In addition, the ET value measured by the cumulative C formula method was 424.2% higher than that of the model method and exceeded the storage capacity. Low-frequency and limited environmental index observations may lead to an overestimation of the real lake evaporation. Therefore, in situ, high-frequency meteorological–water quality monitoring and the eddy method deserve more consideration in future research on lake evaporation. [ABSTRACT FROM AUTHOR]

The goal of this research study is to describe academic issues which have been debated in the field of Chinese geosciences for a century. In 1922, Jonquei S. Lee (Li Siguang) discovered Quaternary glacial relics at Taihang Mountainin eastern China. In 1947, he published his research findings in the magazine Mount Lushan in Glacial Age. The research results had established three Ice Ages: Poyang (Gonzi), Dagu (Minde), and Lushan (Lisi). However, at that time, no Wurm glacial relics of the last Ice Age had been found in Lushan Mountain. Since then, the research team represented by Shi Yafeng, who is considered to be "the father of glaciers in China", questioned Jonquei S. Lee's research results and concluded that "Professor Jonquei S. Lee's Quaternary glacier research in Lushan Mountain having misread the debris flow". In 2005, the "middle‐low mountains" in eastern China were finally defined as follows: "We clearly and unambiguously believe that there were no glacial activities in the middle‐low mountainous areas of eastern China (east of 102° to 104°E; below 3,000 and 2,500 m) during the Quaternary Period". Currently, the long‐standing academic debate appears to have come to a conclusion. As of 2015, the author and others began to investigate and study the Quaternary glacial relics in Mengshan Mountain (1,156m above sea level), Shandong Province, one of the "middle‐low mountains" of eastern China. The relics have been observed to posses the systematic features of glacial erosion, trough and valley striations, and moraine deposits. The applied dating method shave confirmed that there were not only glacial relics of the last Ice Age (Wurm), but also Holocene glacial relics in the Mengshan Mountain area. Therefore, in order to further establish the corresponding relationship between the glacier, loess, stream sediment series, and MIS in the Mengshan Mountain area, a large number of chronological studies have been carried out regarding the various types of sediments in the area, and 24 dating datahave been obtained using OSL, CRN, and 14Cmethods. On this basis, the corresponding relationship between the sedimentary sequences and the MIS was established for the first time in eastern China, which in dicates the environmental changes which had occurred in eastern China since 80ka. These discoveries s and chronological study results confirm the existence of the Last Ice Age, as well as Holocene glacial relics at Mengshan Mountain, there by confirming that Quaternary glaciation had occurred in the middle‐low mountain areas of eastern China. [ABSTRACT FROM AUTHOR]

China is a crucial region for investigating the relationship between climate change and hominin evolution across diverse terrestrial ecosystems. With the continuous development of palaeoclimatology, chronology, and archaeology, the environmental and hominin record of the Early and Middle Pleistocene in China is steadily accumulating, shedding light on the effects of climate change on the distribution of early human settlements and population dynamics. However, the migration and dispersal of these early humans within long-term climate fluctuations and their underlying mechanisms remain to be clarified. Based on the spatial-temporal distribution of 95 Early to Middle Pleistocene archaeological sites in China, we found that intensified hominin activities gradually shifted southward under the influence of multiple glacial–interglacial cycles. The frequent bidirectional movements of these early humans between north and south were assumed as follows. During glacial periods, hominins living in North China migrated to southern areas, while inter-glacial periods witnessed the northward expansion of hominins inhabiting South China. Among all the potential driving mechanisms, we suggest that the available resources in terrestrial ecosystems may be the most fundamental factor. Combined with paleoenvironmental and archaeological records, we provide an Asian perspective for a better understanding of how the glacial–interglacial cycles shaped early human evolution. [ABSTRACT FROM AUTHOR]

Late Pleistocene paleoclimatic history on northeastern Qinghai-Tibetan Plateau (QTP) has been reconstructed mainly from lake sediments; however, data regarding dry-wet climate changes reported in this region are still not clear and controversial. Based on shoreline features and highstand lacustrine sediments around lakes on the QTP, high lake level histories in this paper were summarized and compared with paleoclimatic records from lake sediments, ice core and glaciation evolution surrounding mountains on the NE QTP during late Pleistocene. The results indicate that periods of high lake level occurred at MIS 5, MIS 3 and early-middle Holocene and most likely corresponding to warm and wet climate periods, while periods of low lake level existed in intervening intervals, corresponding to cold and dry climate periods, which most likely coincide with glacial advances surrounding high mountains. With an exception, no wide glacial advance in study area was found during MIS 3, possibly suggesting that effective moisture is lower than that in the other region of NE QTP in this period. [ABSTRACT FROM AUTHOR]

The aeolian deposits in the coastal region of North China are important for reconstructing paleoclimate. In this paper, chronology, climatic proxies and chemical compositions of four loess sections were studied. Optically stimulated luminescence (OSL) dating results indicate that the coastal loess was accumulated during late Quaternary, with ages ranging from the penultimate glacial period to the latest Holocene. Both granulometric characteristics and geochemical properties indicate that the dust provenance of the coastal loess is partially different from that of the Chinese Loess Plateau, characterized by more proximal contributions. Except distal dust transported by northwesterly winter winds from the inland gobi and sand deserts, the coastal loess also contains proximal, local coarse particles, which were derived from the exposed shelf as well as neighboring hills. Multiple climatic proxies, including color, magnetic susceptibility and particle size parameters, correlate well with the marine SPECMAP δ18O record, indicating that climatic changes in the coastal region of North China during the late Quaternary was mainly controlled by variations of the East Asian monsoon, driven by changes in global ice volumes. • Luminescence dating of coastal loess in eastern North China. • Coastal loess contain both distal and proximal source materials. • Exposed shelf during glacial time serving as an important source for coastal loess. • Costal loess reflects orbital climatic fluctuations driven by East Asian monsoon. [ABSTRACT FROM AUTHOR]

Depositional evidence for glaciation (dropstones, diamictites) is common in Neoproterozoic strata, and often debated, but erosional evidence (e.g., unconformities cut directly by ice) is rare. Only two such unconformities are known to have been well preserved globally from the Ediacaran Period (in western Australia and central China). This paper provides the first full description of a spectacular subglacial landscape carved beneath ice masses in the Shimengou area of central China, with classical subglacial bed forms including general faceted forms, müschelbruche, cavetto, spindle forms, and striations that testify to an abundance of meltwater during subglacial erosion. These features were produced during the southward, somewhat sinuous, flow of a temperate to polythermal ice mass. [ABSTRACT FROM AUTHOR]

The Sturtian (720–670 Ma) glacial–interglacial transition period was an important interval for sedimentary manganese metallogenesis, including the Mn oxide deposit in the Otjosondu region in Namibia and Mn carbonate deposits in the Datangpo Formation in the south-eastern Yangtze Platform, South China. During this period, Earth experienced the breakup of Rodinia, the Sturtian glaciation, and the Neoproterozoic oxygenation event. In this study, we investigate scenarios that might have provided geologically and geochemically favorable conditions for Mn metallogenesis. In these scenarios, the global recovery of microorganisms enhanced marine primary productivity and O2 levels of the hydrosphere and atmosphere during the Sturtian glacial–interglacial transition. However, the water column was not completely oxidized, maintaining redox stratification. Transgression–regression cycles or O2-rich downwelling drove the exchange of oxygenated topwater and anoxic deep water in rift-related basins that developed due to Rodinia's breakup. The coupling of these processes precipitated existing dissolved Mn(II) at the margins of basins (Otjosondu region) or at their centers (Yangtze Platform). In the latter case, precursor Mn oxides were further converted into Mn carbonates via the reduction of Mn oxides coupled with organic matter oxidation during early diagenesis. A brief review of Mn metallogenesis in the geological record reveals that Mn metallogenic processes typically occur under geo-environmental conditions that, in concert, produce favorable conditions for Mn sourcing, concentration, and sedimentation. [ABSTRACT FROM AUTHOR]

Loess is a product of aeolian deposition during Quaternary glaciation cycles. Loess–paleosol sequences are rich in calcareous nodules (CNs). In the literature, two models are widely cited for the formation of CNs, namely “per descendum” and “per ascendum”. However, there has been no direct testing or monitoring to support either of these contradictory models. This paper reviews a large number of multidisciplinary literature to evaluate the consistency, reliability and rationality of these two models. Three main conclusions are drawn: (1) the causative factors (variation of pH value along loess–paleosol sequence, decrease of CO 2 partial pressure, and reduction of solvent water) that are used to support the per descendum model do not completely explain the supersaturation of infiltration solution with CaCO 3 , thereby making this model questionable; (2) the per ascendum model explains the formation of CNs along narrow horizons through upward evaporation; however, it fails to produce sporadic distributions and irregular shapes of nodules on loess slope faces and the frequent appearance of nodules around plant roots. In order to reconcile these deficiencies, we conducted an extensive field survey in various parts of Shanxi province. Based on this new set of observations, it was concluded that the “per ascendum” model can be extended to explain all occurrences of CNs. This extended model is called “per evapotranspiration”. [ABSTRACT FROM AUTHOR]

The Ordovician-Silurian (O S) transition witnessed dramatic tectonic, climatic, marine, and biological coevolution, during which organic-rich black shale was widely deposited and is considered an important source rock. However, the potential links between the differential enrichment pattern of organic matter and climate fluctuations and paleoenvironmental evolution during this period are still unclear. In this paper, the Late Ordovician-early Silurian black shale in a JieLong (JL) section in South China was identified by graptolitic fossils, total organic carbon (TOC) content, X-ray diffraction (XRD), scanning electron microscopy (SEM) and geochemical analysis. The results show that the provenances of sedimentary rocks are all granodiorite-like. According to the variations in the TOC content and geochemical indicators, four layers are delineated. Under warm and humid climatic conditions, sea level rise and unstable seasonal upwelling led to Unit 1 organic matter enrichment controlled by high primary productivity, anoxic conditions and effective smectite production. Unit 2 organic matter burial was controlled by cold, arid and oxic environmental conditions, but primary productivity was still relatively high. After the end of the glacial period, warm and humid climatic conditions and rapid transgression were the main factors affecting the burial of organic matter in Unit 3. Under hot and humid climate conditions, higher terrigenous detrital inputs and unfavourable preservation environments, the dilution of organic matter in Unit 4 was accelerated. The corrected chemical index of alteration (CIA corr) values show that the study area experienced a climate change of alternating cold and warm conditions in response to the climate fluctuation during the glacial-interglacial period. The CIA corr value is negatively correlated with the TOC content, while the generation of available clay minerals (smectite) in warm and humid climates is usually consistent with the enhanced burial flux of organic matter, supporting the important role of climate fluctuations in the accumulation of organic matter. Finally, a comparison of the data from the present study with geochemical data from different profiles in South China reveals the role of climatic fluctuations during the O S transition in controlling paleoenvironmental evolution and organic matter enrichment, while such a heterogeneous factor is usually associated with global or regional geological events. Our study highlights this differential enrichment mechanism as a combined response of multiple factors and provides important implications for glacial-interglacial organic matter enrichment mechanisms. • Rapid changes of weathering indices imply climatic fluctuations during the Late Ordovician-Early Silurian. • Four different patterns were established for organic matter accumulation across the O/S. • Climate fluctuations and the heterogeneity nature of ocean systems explain the regional variations of OM accumulation. [ABSTRACT FROM AUTHOR]

In recent years, coastal areas have been threatened by many potential hazards due to global warming, glacier melting and sea level rise. Understanding their evolutionary history and development trends can help predict disasters and further reduce the corresponding losses. The Hanjiang River delta in the southeastern part of China is the second largest delta in Guangdong Province and has such challenges. Studying the sedimentary evolution and delta initiation of the Hanjiang Delta is beneficial for understanding the response of the Hanjiang Delta to present and future sea level and climate changes. In this research, we drilled a series of cores from the Hanjiang subaqueous delta, which contains information on the sedimentary environment, climate change and sea level change during the late Quaternary. Combined with previous research results and under the constraint of high-precision and high-resolution AMS14C and OSL, we carried out a multi-proxy analysis that included micropaleontology and grain size to obtain information on the sedimentary environment, sea level change and climate change. We then further discussed the initiation of the Hanjiang delta and its primary factors. The Quaternary sediments began depositing in the early Late Pleistocene (MIS5), and three sedimentary cycles can be recognized from bottom to top. The dating results also indicate that the first two cycles were formed during the late Pleistocene, while the last cycle was formed during the Holocene. The initiation of the Hanjiang Delta was indicated by a progradation in the process of a transition from estuary to a typical delta. At this time, the rate of delta progradation seaward was fast, and increasing amounts of sediments moved through the third line of islands into the sea. The barrier–lagoon system began to develop in the estuary of Hanjiang during this period. With the sequential construction of the delta, the lagoon was filled and covered by delta deposition, and the barrier bar moved to the sea; thus, the barrier-coast delta depositional model was established in the study area. Since the last glacial period (LGM), the Hanjiang River Delta and other river deltas in the region seem to have experienced similar evolutionary histories, including the filling of incised paleo-valleys and estuaries in the Early Holocene and deltaic progradation in the Middle to Late Holocene, controlled by sea level change. [ABSTRACT FROM AUTHOR]

The rainfall changes in East Asian summer monsoon (EASM) regions on the orbital timescale remain controversial due to the lack of reliable rainfall records. Here, we present new multiproxy records (δ18O, δ13C, Sr/Ca and Mg/Ca) of a 230Th-dated stalagmite from Hulu Cave in central eastern China. Multiproxy records reconstruct a regional hydroclimate history from 340 to 261 kyr BP (thousand years before present), approximately covering the antepenultimate glacial period. The δ18O record is dominated by the precessional cycles, suggesting that EASM responds to changes in Northern Hemisphere summer insolation (NHSI) on the orbital timescale. Significant correlations amongst the δ13C, Sr/Ca and Mg/Ca suggest that a common factor, i.e., the local hydrological cycle, controlled their variability, and their leading principal component can be used as a proxy linked to regional rainfall. This composite record bears a good similarity to those from the Chinese Loess Plateau, showing a gradually decreasing rainfall during the antepenultimate glacial period, consistent with changes in global ice volume. Superimposed on the long-term trend, three relative wetter intervals were responding to the higher NHSI periods, suggesting that EASM rainfall variability was induced by integrated effects of global ice volume and NHSI. The increased ice sheets and lower NHSI resulted in an increased meridional temperature gradient and southward shift of the westerlies, which shortened the duration of Meiyu and midsummer rainfall. The differences between the rainfall record and the stalagmite δ18O record indicate that the latter represents the overall EASM intensity linked to monsoon circulation, but does not directly reflect the rainfall changes at the cave sites. [ABSTRACT FROM AUTHOR]

The Quaternary was the main evaporite deposition period in the Qaidam Basin (QB), but the correlation between the evaporite deposition period and the glacial period is still unclear. In this study, the research objects are primarily evaporite‐bearing strata in a 461.58 m‐long drill core in the QB. X‐ray powder diffraction (XRD) and scanning electron microscopy (SEM) were applied to study the evaporite minerals, U‐Th dating being applied to construct the 230Th geochronological framework. Evaporite deposition from Marine Isotope Stage (MIS) 15 to MIS 4 in the borehole was reconstructed via mineralogical and geochronological data. The evaporite minerals are mainly halite (NaCl), mirabilite (Na2SO4·10H2O), thenardite (Na2SO4) and gypsum (CaSO4·2H2O). A total of 9 effective 230Th data points, ranging from 492.5 ± 43.0 ka to 62.0 ± 11.9 ka, were obtained. The depositional age of the earliest halite layer in the borehole is 592.5–563.0 ka. There were mirabilite deposits in the QB during the cold glacial environment of MIS 6. During MIS 4, the study area desiccated, with mirabilite and halite being deposited. This study suggests that mirabilite is an indicator mineral for the glacial environment in the QB, while halite deposition does not correspond well to glaciation. [ABSTRACT FROM AUTHOR]

Organic carbon isotopic composition (δ13Corg) in loess deposits is an important indicator of terrestrial paleovegetation, and it has been widely used for paleoenvironmental reconstruction in aeolian sediments around the world. However, little research has been done on the variation and paleoenvironmental implication of δ13Corg from loess deposits on Shengshan Island, East China Sea, during the last glacial period (LG). In this research, we present optically stimulated luminescence (OSL) ages, total organic carbon (TOC) data and δ13Corg records of the loess section at Chenqianshan (CQS) on Shengshan Island. Additionally, to study the effectiveness of δ13Corg in documenting paleoenvironmental changes, magnetic susceptibilities and diffuse reflectance spectra were surveyed. TOC concentration for the CQS loess section ranged from 0.11% to 0.47%, and the δ13Corg composition of the CQS loess section varied between −20.80‰ and −24.56‰ during the LG. The average value of C4 abundance was 21.31%. TOC, δ13Corg, χfd, and Hm/(Hm + Gt) curves for the CQS loess section showed similar patterns. The results of our study indicated that the vegetation of the CQS loess deposit was mainly C3/C4 mixed vegetation, and C3 vegetation was the most important vegetation. The comparison between the δ13Corg curve for the CQS section and other existing δ13Corg records of the loess sections from central and northern China showed similar trends and their vegetation succession exhibited synchronous change during the LG. Based on a comparison of the δ13Corg record, C4 abundance and χfd of the CQS section and other global geological records, it was concluded that the mutual effects of precipitation and temperature caused the change of paleovegetation in loess deposits on islands in the East China Sea during the LG. [ABSTRACT FROM AUTHOR]

As a result of the influence of plate movement, the upper reaches of Jinsha River have strong geological tectonic activities, large topographic fluctuations, and complex climate characteristics, which result in the frequent occurrence of landslide disasters. Hence, there is the need to carry out landslide susceptibility mapping in the upper reaches of Jinsha River to ensure the safety of local people's property and the safe exploitation of hydraulic resources. In this study, InSAR technology and a field geological survey were used to map the landslides. Then, the curvature watershed method was used to divide the slope units. A conditioning factor system was established, which can reflect the characteristics of the rapid uplift and vertical distribution of rainfall in the special geological environment of the study area. Finally, logistic regression, random forest, and artificial neural network models were used to establish the landslide susceptibility model. The results show that the random forest model is optimal for the landslide susceptibility mapping in this area. Additionally, the area percentages of the very low, low, moderate, high, and very high susceptibility classes were 40.13%, 20.06%, 13.39%, 12.55%, and 13.87%, respectively. Based on the analysis of the landslide susceptibility map, we suggest that the landslide geological hazards resulting from the rapid uplift of the Tibetan Plateau and the significant decrease in sea level during a glacial period in the upper reaches of Jinsha River are controlled by the double disaster effect of the geodynamic system. Consequently, this study can guide local prevention and mitigation. [ABSTRACT FROM AUTHOR]

The Huanglong travertine landscape, which is located on the eastern edge of the Qinghai‐Tibet Plateau, is a World Natural Heritage Site with important tourism, aesthetic and scientific research value. However, no convincing travertine sedimentary age data have been reported for this area, and these late Cenozoic terrestrial carbonates have not been effectively included in studies of the Qinghai‐Tibet Plateau geological environment. In this study, U‐series dating of the travertines was carried out using a multi‐collector inductively coupled plasma mass spectrometer to determine a time series for travertine deposition in the Dawan Valley (only a mountain away from Huanglong). The analyses of the processes operating during travertine deposition as the trench system evolved are performed based on a comprehensive study of the geological setting, structure and glacial landforms. The results suggest that travertine deposition in the Dawan Valley started at ca 13 ka and had begun to wane by the early Holocene (ca 7 ka). At the same time, the Huanglong Valley travertines began to be deposited on a large scale in response to a hydrological transition event. This event might reflect tectonic activity in particular, or possibly earthquakes or glacial retreat caused by climate warming. The findings reported here provide age data for late Cenozoic geological and environmental events such as climate variations and continental activity on the eastern margin of the Qinghai‐Tibet Plateau. It also presents new insights for research on glaciation, tectonic activity and seismicity; however, depositional breaks and forcing factors need to be explored further. [ABSTRACT FROM AUTHOR]

Abstract: In the regions surrounding the Qinghai Tibet Plateau, changes in erosion rates have been linked to the tectonics, climate and topography over different time scales. To understand the mechanisms governing the changes of erosion rates, it is important to study erosion rates by different methods and for different time scales. In inland drainage basins, deposition rates of terminal lake sediments can indicate basin-wide erosion rates at the millennial-scale. This paper presents three lake records of the Last Deglaciation and Holocene (Huahai Lake, Zhuye Lake and Yanchi Lake) from the Hexi Corridor, north of the Qilian Mountains, in arid China. Organic matter, terrestrial pollen concentrates, seeds, grasses and plant debris are used for conventional and AMS 14C dating. On the basis of 66 radiocarbon dates, lithology and grain-size, we infer relatively high basin-wide erosion rates during the Last Deglaciation and early Holocene in the three drainage basins, when the three lake sediments were seriously affected by reworking. The deposition rates were an order of magnitude or greater in these lakes during the Last Deglaciation and early Holocene than during the mid-to-late Holocene. During the transition period of the last glacial–interglacial cycle, significant climatic changes occurred in East and Central Asia, corresponding to the strengthening of the Asian summer monsoon and to increasing effective moisture in arid Central Asia, which can have strong impacts on basin-wide erosion rates north of the Qinghai Tibet Plateau. Moreover, melting glaciers in the Qilian Mountains probably also contributed to the high basin-wide erosion rates. At the same time, tectonic activity was not recognizable in the study area during that period. In the arid and semiarid regions surrounding the Qinghai Tibet Plateau, dramatic changes in erosion rates appear during the transition periods of the glacial–interglacial cycles, which illustrate the climatic controls on erosion rates at this time scale. [Copyright &y& Elsevier]

This is a response to: Knight, J., 2012. The shape of glacial valleys: comment on Hall (2010). South African Geographical Journal, http://dx.doi.org/10.1080/03736245.2012.663953. This was in turn a comment on: Hall, K., 2010. The shape of glacial valleys and implications for southern African glaciation. South African Geographical Journal, 92, 35–44. [ABSTRACT FROM AUTHOR]

A multidisciplinary fieldwork and research project was recently begun at the Yangshang site (220–140 ka), a late Early Paleolithic locale in the western Chinese Loess Plateau. 1696 lithic artifacts and 337 faunal remains were recovered during the excavation. Sedimentological and paleoenvironmental investigations indicate the site preserves a relatively long and minimally disturbed archaeological sequence associated with paleoenvironmental changes during MIS 7–6. A detailed techno-typological analysis of Yangshang's lithic assemblages was undertaken to examine the influence of glacial cycles on late Middle Pleistocene hominin technological strategies in the western Chinese Loess Plateau. The results show that while the Yangshang site is dominated by quartz-based core/flake assemblages typical of most Early Paleolithic sites in North China, the lithic assemblages provide evidence that different provisioning systems existed during the penultimate glaciation. We argue that these shifts reflect changes in land use and mobility that were tied to climate change. Our results suggest that theoretically informed statistical analyses of so-called unchanging and crude lithic technology can yield meaningful evidence for behavioral shifts. [ABSTRACT FROM AUTHOR]

Focusing on the Shuixiakou Section (Xikou area, Zhen'an County, Shaanxi Province, southeastern Qinling region, China), the Roadian-Wordian conodonts are investigated. More than 2 000 conodont elements including 6 genera and 14 species have been obtained. Based on these materials, the Guadalupian Jinogondolella nankingensis and J. aserrata zones have been recognized. The Roadian-Wordian boundary is tentatively defined by the first occurrence of J. aserrata in the lower part of Unit III in the Shuixiakou Formation. The sedimentary succession of Xikou area records similar sea-level changes to those observed in Laibin area (South China). The 40 m-thick bioclastic limestone of Unit IV in this section can be correlated with the reefs of Bed 114 in Laibin area. A temperature drop indicated by δ18Oapatite values suggests this Wordian interval coincides with a period of glaciation and global regression. [ABSTRACT FROM AUTHOR]

Detailed organic carbon isotope (δ13Corg) measurements were conducted on two peat sequences recovered from the north bank of the Yangtze River, East China. Seven radiocarbon dates provided firm age control of this δ13Corg record and reveal palaeoclimatic changes since the Late Glacial period. The results show that the Holocene Megathermal Maximum occurred between 8385 and 7040 cal. yr BP. The Late Glacial climate was generally cold but fluctuated frequently between 12940 and 11815 cal. yr BP. The Older Dryas (from 12940 to 12810 cal. yr BP) and the Younger Dryas (from 12645 to 12170 cal. yr BP) were characterised by cold climate conditions. In contrast, 12810 to 12645 cal. yr BP (corresponding to the Allerød Warm Period) and 12170 to 11815 cal. yr BP (corresponding to a rapid warming period after the Younger Dryas, marking the beginning of the Holocene) were relatively warm phases. In contrast to other high-resolution records, it shows that the δ13Corg records of our study peats are largely controlled by a common forcing mechanism of solar insolation changes in the Northern Hemisphere, and exhibit similar variability to δ18O records obtained from stalagmites and GISP2 during the Late Glacial and early-mid Holocene. [ABSTRACT FROM AUTHOR]

The Last Glacial Maximum (LGM; 21 ka BP) was the most recent glacial period when the global ice sheet volume was at a maximum. Therefore, the LGM can be used to investigate atmospheric dynamics under a climate that differed significantly from the present. This study quantitatively compares pollen records of boreal summer (June–July–August) precipitation with the PMIP3 LGM simulations. The data-model comparison shows an overall agreement on a drier than pre-industrial East Asian summer monsoon (EASM) climate. Nevertheless, 17 out of 55 records show a regional precipitation increase that is also simulated over the additional land mass area due to sea level drop. The thermodynamic and dynamic responses are analyzed to explain a drier LGM EASM as a combination of these two antagonistic mechanisms. Relatively low atmospheric moisture content was the main thermodynamic control on the lower LGM (relative to pre-industrial levels) EASM precipitation amounts in both the reconstructions and the models. In contrast, two dynamic processes in relation to stationary eddy activity act to increase EASM precipitation regionally in records and simulations, respectively. Precipitation increase in records is explained by dynamic enhancement of the horizontal moisture transport, while dynamic enhancement of the vertical moisture transport leads to simulated precipitation increase over the specific region where landmass was exposed during LGM along continental coastlines of China due to significant drop in sea level (relative to pre-industrial levels). Overall, the opposing effects of thermodynamic and dynamic processes on precipitation during the LGM provide a means to reconcile the spatial heterogeneity of recorded precipitation changes in sign, although data-model comparison suggests that the simulated dynamic wetting mechanism is too weak relative to the thermodynamic drying mechanism over data-model disagreement regions. [ABSTRACT FROM AUTHOR]

The Tarim Craton, China, records several significant events in the history of the Rodinia supercontinent, including Neoproterozoic glaciations and rift evolution. In this study, we use geochronological, geochemical, and geophysical data from the Aksu region, northwest Tarim Craton, to investigate the rifting history and three discrete Cryogenian glaciations in the Tarim Craton. A total of 268 concordant zircon U–Pb ages were obtained from three samples in the lowermost unit of the Cryogenian Xifangshan Formation. These ages define four Neoproterozoic populations of ca. 975–900, 885–810, 795–755, and 740–720 Ma, which reflect magmatic events in the Rodinia supercontinent. The age of the Xifangshan Formation is constrained by two maximum depositional ages of 739 ± 9 Ma and 719 ± 7 Ma, suggesting a stratigraphic correlation with the Cryogenian Baiyisi Formation in the Kuruktag region, northeast Tarim Craton. Field and geochemical evidence identify three discrete Cryogenian glaciations in the Aksu region, which are the Xifangshan, Qiaoenbrak, and Youermeinark glaciations that can be chronologically correlated with the Baiyisi, Altungal, and Tereeken glaciations in the Kuruktag region, respectively. The northern rift basin in the Aksu region formed at ca. 740 Ma and is filled by a thick Cryogenian volcanic–sedimentary succession. This rift basin gradually expanded to entire northern Tarim Craton, with sediments being unconformably deposited on underlying formations. Although large-scale deformation occurred in the late Ediacaran, corresponding to the Pan-African orogeny, the Aksu rift depocentre was covered with a series of deep-water rocks in the Early Cambrian and Ordovician. [ABSTRACT FROM AUTHOR]

Orographic and climatic oscillations have played crucial roles in shaping the nucleotide diversity and evolutionary history of many species across the Northern Hemisphere. In this study, based on 10 nuclear loci and a chloroplast DNA marker, we analyzed the nucleotide polymorphisms and demographic history of the endangered conifer species Pinus bungeana in Northwest China and investigated the phylogenetic relationships between P. bungeana and two related species, that is, Pinus gerardiana and Pinus squamata. We found that P. bungeana exhibited an extremely low level of nucleotide diversity (πsil = 0.00159). Demographic simulations based on DIYABC analysis showed that P. bungeana underwent demographic expansion and contraction during the Miocene. According to ecological niche modeling, we found that this species survived in situ during the glacial period and was not restricted to southern refugia. We speculate that P. bungeana may have experienced widespread population shrinkage from the Last Interglacial to the Last Glacial Maximum due to geological or climatic events. Isolation‐with‐migration analysis revealed that the divergence (~2.4–4.2 Ma) among P. bungeana and its related species was significantly associated with the Qinghai–Tibetan Plateau uplift events in the mid‐to‐late Tertiary period. Species tree analyses suggested that these three related Pinus species formed a monophyletic clade with high bootstrap support. These results suggest that the Miocene–Pliocene and Pleistocene geological and climatic fluctuations might have profoundly affected the nucleotide diversity and demography of this psychrotolerant conifer species in western China. [ABSTRACT FROM AUTHOR]

The distribution of soil moisture in loess-paleosol sequences is a critical factor that impacts the regional environment in the Chinese Loess Plateau (CLP). In this study, samples were collected from the Xiushidu (XSD) profile at the southern edge of the Jinghe River in Guanzhong Basin; specifically, the Holocene-Middle Pleistocene Lishi strata loess. They were then dry weighed, and moisture content and grain size distribution were determined using the grain size testing method. The impacts of different soil textures, sedimentary environments and other factors on the XSD profile moisture distribution in the study area were examined. The results showed that: (1) During the sequence change process from top to bottom, the soil moisture content of the loess-paleosol sequence increased and the overall average moisture content of the XSD profile was ranked in a descending order as: the middle layer of Middle Pleistocene Lishi loess > the upper layer of Middle Pleistocene Lishi loess > the Holocene > the Late Pleistocene; (2) When film water was predominant, the correlation coefficients for soil moisture content and clay, fine-silty sand, coarse silt sand and microsand content were 0.389, 0.394, − 0.419 and − 0.451, respectively; (3) In adjacent loess and paleosol layers, the soil moisture content of the overlying loess layer was always greater than the underlying paleosol layer. (4) In the same loess layer, minimum moisture content values were subject to the East Asia winter monsoon; as such, they often appeared in the middle layer of this glacial period. In the same paleosol layer, the opposite trend was observed. [ABSTRACT FROM AUTHOR]

The Neoproterozoic glaciations represent a milestone in the Earth evolution due to their influence on atmosphere, biosphere and hydrosphere. Evidence for the Sturtian glaciation, the early stage of Cryogenian, has been recorded worldwide, but the precise timing and synchroneity of its counterpart, the Chang'an glaciation, in South China have been controversial. As such, new zircon U–Pb ages from the pre-Sturtian Gongdong Formation and the overlying the Chang'an Formation in southeastern Yangtze Block were reported. The youngest U–Pb zircon age from a tuff sample of the topmost Gongdong Formation was 716.8 ± 6.8 Ma, and that from a sandstone sample of the lower Chang'an Formation was 725.9 ± 4.4 Ma. The zircon weighted mean age of 716.8 ± 6.8 Ma was interpreted as the maximum depositional age of the termination of the Danzhou Group. This age, along with the ages reported from the bottom of the Danzhou Group, constrains deposition of the Danzhou Group to between ca. 820 Ma and ca. 715 Ma. The age of 716.8 ± 6.8 Ma from the top of the Gongdong Formation is consistent with the SIMS U-Pb age of 715.9 ± 2.8 Ma from the Sibao section, as well as ages from the Banxi Group, Liantuo Group, and Kaijianqiao Formation in the Yangtze Block, which further constrain the onset time of the Sturtian glaciation in South China at ca. 715 Ma. It is also, with uncertainties, consistent with ages from pre-Sturtian strata in Laurentia and Oman, which indicates a global synchroneity and extent for the Sturtian glaciation. [ABSTRACT FROM AUTHOR]

Cryptocercus cockroaches are remarkable for their similarity in external morphology while having a diversity in chromosome numbers. Most species are therefore delimited by karyotyping combined with phylogenetics. However, the investigation of chromosome diversity within a limited region is not well-studied, and the causes of their geographic distribution patterns remain unclear. Here, we applied a multipronged set of analyses that included external morphological analysis, chromosomal data, molecular species-delimitation methods and phylogenetic reconstruction after extensive sampling on the Western Sichuan Plateau (WSP) in western China. As a result, six new species were discovered, which increases the known species in WSP to 15. Multiple extinction-isolation events caused by the lifting of the Qinghai-Tibetan Plateau and by glacial periods likely account for the present-day distribution of WSP species. For Manchurian species, major extinctions may have been caused by the Quaternary glaciation and Cenozoic volcanic activities. We believe that three factors shaped the current distribution of Cryptocercus karyotypes: (1) a variability of chromosomes, (2) their low capability for dispersal, and (3) their vulnerability to climate change. [ABSTRACT FROM AUTHOR]

The Neoproterozoic successions in the Aksu region, NW China, which lies unconformably on the Precambrian Aksu Group basement, comprises the Qiaoenbrak, Yuermeinak, Sugetbrak, and Chigebrak formations (from bottom to top). The two lowermost units include two distinct glacial diamictites, which indicate distinct episodes of glaciations. We report the major and trace element (including rare earth element) data for the Qiaoenbrak, Yuermeinak, and Sugetbrak formations to identify the paleoclimatic perturbations. The chemical index of alteration (CIA) values show variations from Qiaoenbrak to Yuermeinak, then Sugetbrak formations. The diamictites have relatively lower chemical index of alteration values (45.23-59.64) than inter-, post- and non-glacial sediments (48.28-66.96). This result supported the condition that the diamictites underwent relatively weak chemical weathering from a dry-cold sedimentary environment, which is associated with the sedimentary facies description. The lower Neoproterozoic successions recoded at least two glaciations, one is Qiaoenbrak glaciation and the other is Yuermeinak glaciation. [ABSTRACT FROM AUTHOR]

The Earth has undergone a significant climate switch from greenhouse to icehouse during the Plio-Pleistocene transition ( PPT) around 2.7-2.4 million years ago (Ma), marked by the intensification of the Northern Hemisphere glaciation ( NHG) ~2.7 Ma. Evidence based on oceanic CO2 [( CO2)aq], supposed to be in close equilibrium with the atmospheric CO2 [( CO2)atm], suggests that the CO2 decline might drive such climate cooling. However, the rarity of direct evidence from [ CO2]atm during the interval prevents determination of the atmospheric CO2 level and further assessment on the impact of its fluctuation. Here, we reconstruct the [ CO2]atm level during 2.77-2.52 Ma based on a new developed proxy of stomatal index on Typha orientalis leaves from Shanxi, North China, and depict the first [ CO2]atm curve over the past 5 Ma by using stomata-based [ CO2]atm data. Comparisons of the terrestrial-based [ CO2]atm and the existed marine-based [ CO2]aq curves show a similar general trend but with different intensity of fluctuations. Our data reveal that the high peak of [ CO2]atm occurred at 2.77-2.52 Ma with a lower [ CO2]aq background. The subsequent sharp fall in [ CO2]atm level might be responsible for the intensification of the NHG based on their general temporal synchronism. These findings shed a significant light for our understanding toward the [ CO2]atm changes and its ecological impact since 5 Ma. [ABSTRACT FROM AUTHOR]

Investigation of climatic conditions prior to the Sturtian glaciations is critical to understanding the trigger mechanism for the series of Neoproterozoic global glaciations. In this study, we report high-resolution chemical index of alteration (CIA) records in the sediments of South China prior to the Sturtian glaciation (820∼720 Ma). Our results showed there occurred multiple climate cooling before the Sturtian glaciations in South China: (1) a series of episodic and possibly global climate cooling periods from ca. 750 Ma to 725 Ma, which also caused some diachronous regional glaciations; (2) a permanent climate cooling period between ca. 800 Ma and 770 Ma, probably contemporaneous to the global "Bitter Springs stage"' δ13C negative excursion; (3) a climate cooling period between ca. 815 Ma and 810 Ma. The three stages of climate cooling are also supported by their correspondence to previously reported extremely low δ18O records of igneous/metamorphic minerals from South China. These climate cooling periods also coincide with the magmatism and rifting events in South China. We argue that tectonic movements were the primary control on the climate cooling before the Neoproterozoic global glaciations. [ABSTRACT FROM AUTHOR]

The main old lands in China include the North China Block (NCB), South China Block (SCB) and Tarim Block (TRB), all of which have individual tectonic evolving histories. The NCB experienced complex geological evolution since the early Precambrian onwards, and carries important records from the old continental nuclei, giant crustal growth episode and cratonization (stabilitization), then to the Paleoproterozoic rifting-subduction-accretion-collision with imprints of the Great Oxygen Event (GOE), and to the Late Paleoproterozoic-Neoproterozoic multi-stage rifting representing North China platform tectonic features. The TRB has two-layer basement of the Early Precambrian metamorphic complexes and Neoproterozoic sedimentary sequences. Three till sheets have been reported. The SCB consists of the Yangtze Block (YZB) and Cathaysia Block (CTB) that were cohered in the Neoproterozoic. The YZB recorded tectonic processes of the Early Precambrian crustal growth, 1.0-0.9 Ga and 0.8-0.6 Ga metamorphic-magmatic events, and two Neoproterozoic glaciations. The CTB consists of ca. 1.8 Ga, 1.0 to 0.9 Ga and ca. 0.8 Ga granitic gneisses and metamorphic rocks, indicating there was a vast Precambrian basement. The Neoproterozoic sedimentary rocks overlie partly on the basement. That the YZB and CTB have a Neoproterozoic uniform cover layer illustrates the SCB should form, at least, during 1.0-0.9 Ga, corresponding to the Rodinia Supercontinent. The Central Chinese Orogenic System with high-ultra-high-pressure metamorphic rocks supports a suggestion that the above-mentioned three old lands were collided to assemble a unified Chinese Continent during the Pangea orogenic period. [ABSTRACT FROM AUTHOR]

The ~635 Ma Marinoan glaciation is marked by dramatic Earth system perturbations. Deposition of nonmass-dependently 17O-depleted sulfate (SO42-) in worldwide postglacial sediments is, thus far, unique to this glaciation. It is proposed that an extremely high-pCO2 atmosphere can result in highly 17O-depleted atmospheric O2, or the Marinoan Oxygen-17 Depletion (MOSD) event. This anomalous 17O signal was imparted to sulfate of oxidative weathering origin. However, 17O-depleted sulfate occurs in limited sedimentary intervals, suggesting that Earth surface conditions conducive to the MOSD had a finite duration. An MOSD duration can, therefore, provide much needed constraint on modeling Earth system responses at that time. Unfortunately, the sulfate 17O record is often sparse or lacks radiometric dates. Here, we report 11 barite layers from a post-Marinoan dolostone sequence at Wushanhu in the South China Block. The 17O depletion fluctuates in magnitude in lower layers but is persistently absent up section, providing the most confident first and last sedimentary appearance of the anomaly. δ13C chemostratigraphy is used to correlate the Wushanhu section to two proximal sections on the same shallow platform that lack barite layers but have published U-Pb dates that occur in dolostone and shale. Assuming a similar pattern and rate for carbonate and shale deposition among the different sections, we estimate the MOSD duration at 0-0.99 My. This number can be further constrained by new radiometric dates from equivalent sequences worldwide, thus underpinning models on the nonsteady-state Earth system response in the immediate aftermath of the Marinoan meltdown. [ABSTRACT FROM AUTHOR]

Based on the analysis of sedimentary facies and chemical index of alteration (CIA) in Nanhua and Ediacaran Systems in the southwest of Tarim Block, some features of glacial records in Neoproterozoic become more clear. Six sedimentary facies have been divided in the study area, including alluvial fan facies, lacustrine facies, glacial facies, littoral facies, neritic facies, and lagoonal facies, showing that this area underwent a process from continent to marine, with mainly littoral and neritic sedimentation. Two cold events have been recognized by analysis of CIA values in the study area, called Bolong and Yutang glaciation, respectively. They present as thick-layer tillite deposition in the Bolong Formation and thin-layer tillite deposition in the Yutang Formation, respectively. The Bolong glacial period in the study area can be correlated to the Yulmeinak glacial period in Aksu area, Tereeken glacial period in Qurugtagh area, and the Nantuo glacial period in South China, which is equivalent to the universally acknowledged Marinoan glacial period. The Yutang glacial period can be correlated to the Hankalchough glacial period in Qurugtagh, which is equivalent to Gaskers glaciation in Newfoundland. [ABSTRACT FROM AUTHOR]

The Lantian biota at the Lantian Town of Xiuning County, Anhui Province, is preserved in black shales of the Ediacaran Lantian Formation. It yields some of the oldest known complex macroorganisms, including fan-shaped seaweeds and possible animal fossils with tentacles and intestinal-like structures reminiscent of modern coelenterates and bilaterians. The Lantian Lagerstätte sheds new light on the origin and early evolution of multicellular organisms in relatively quiet and deep environments soon after the Neoproterozoic Marinoan glaciation. The morphological complexity and diversity of early multicellular organisms may be closely related to sexual reproduction and alternation of generations. The fluctuation of oceanic redox conditions during this period may have played a role in the ecology and preservation of the Lantian biota. [ABSTRACT FROM AUTHOR]

The Gongga Mountain is the largest area of modern glaciation in the Hengduan Mountains and, with a summit elevation of 7556 m, is the highest mountain on the eastern margin of the Tibetan Plateau. During the Quaternary glacial-interglacial cycles the Gongga Mountain was extensively and repeatedly glaciated, and glacial landforms and outwash deposits from multiple glaciations are well-preserved in valleys, in basins, and on piedmonts. To constrain the glacial chronology of the eastern slope of Gongga Mountain, sample sites were selected based on the distribution and weathering of glacial tills, relationships among glacial deposits, and soil development on moraines. Dating of the tills and glaciofluvial deposits was undertaken with electron spin resonance (ESR) and optically stimulated luminescence (OSL). The ages of the glacial deposits can be divided into four clusters: 2.2±0.5, 11.9±0.6, 35.9±2.7-58.0±6.3 and 119.2±15.9-194.2±32.8 ka. Five glacial advances in this region have been identified, which are equivalent in age to the Little Ice Age (LIA), Neoglaciation, marine oxygen isotope stage (MIS) 2, mid-MIS3, and MIS6. The largest local last glacial maximum (LGM) occurred on Gongga Mountain during mid-MIS3, characterized by a cold-humid climate, rather than the global Last Glacial Maximum (LGM) of MIS2. The Gongga, Nanmenguangou (NMGG) and Yajiageng Glaciations occurred during the late part of the last glacial cycle, the middle of the last glacial cycle and the penultimate glacial cycle, respectively. On the basis of geomorphological, sedimentological, and compositional characteristics, landforms of the Moxi Platform and terraces can be grouped by facies and geochronology. In combination with the dating results, this analysis indicates the basal part of the Moxi Platform between Xinxin and the Moxi Hotel is correlative with the till of the Nanguanmen Glaciation (mid-MIS3). This basal unit has occasional lenses of glaciofluvial sandy gravel and lacustrine sediments. The remainder of the Moxi Platform and the terraces beside the platform are glaciofluvial deposits occasionally mixed with debris flow deposits and range in age from MIS3 to Holocene. [ABSTRACT FROM AUTHOR]

Isolated NE-SW stretching the Helan Mountain massif, separating the temperate grassland of the Ordos plateau from the Tenggeli Desert, is a key position of studying the glacier development in west China as well as the coupling conditions of climate change with tectonic uplift. The glacial landforms and deposits including cirques, peaks, knife-edge ridges, lateral moraines, and terminal moraines distribute above 2800 m a.s.l. in the middle part of the Helan Mountain. This distribution indicates that here was once glaciated during the late Quaternary. Morphology features show a clear sequence of landscape forming events took place throughout the Helan Mountain. Laboratory optically stimulated luminescence (OSL) and accelerator mass spectrometry radiocarbon dating (AMS C) results indicate a late history of glacial advance. Late Pleistocene glaciers in the middle part of the Helan Mountain advanced to near their positions at least four times, and the glacial sequences can be assigned as the middle stage of last glacial cycle (MIS3b, 43.2±4.0 ka), last glacial maximum (LGM, ∼18 ka), late glacial (12.0±1.1 ka) and neo-glacial (3.4±0.3 ka) respectively. Adopting equilibrium line altitude ∼2980 m of last glacial maximum and the modern theoretical snowline altitude ∼4724 m as the maximum amplitudes, and the standard marine isotope curve (MIS) as the glacial equilibrium line change since the Gonghe Movement (150 ka), the relationship between the mountain altitude and glacier development is discussed herein. Compared with other environmental indexes such as the loess-paleosol and ice core, conclusions are made that glacier advances in the Helan Mountain during the late Quaternary obviously depended on the coupled control of tectonic uplift of mountain with the climate condition. It is at last glaciation that the mountain reached the altitude above snowline and coupled with the glacial climate. The glacial advances occurred in the early and middle stages of last glacial cycle after the Gonghe Movement. [ABSTRACT FROM AUTHOR]

Neoproterozoic sedimentary sequences in the South China Block provide great opportunity to examine the tectonic evolution and crustal accretion during this period. This study presents U-Pb ages and Hf isotope composition of detrital zircons and Nd isotope composition of whole rocks of the Neoproterozoic sequences from the Yangtze Block, part of the South China Block. Age patterns of detrital zircons imply that the source area experienced three major periods of magmatic activity at 2,300-2,560, 1,900-2,100 and 770-1,000 Ma and two major episodes of juvenile crust accretion at 2,600-3,400 and 770-1,000 Ma. The maximum age of the Gucheng glaciation can be restricted at ~768 Ma from the youngest detrital zircon ages, probably corresponding to the Kaigas glaciation rather than to the Sturtian glaciation. High La/Sc ratio and low Cr/Th, Sc/Th and Co/Th ratios of the sedimentary rocks point to a derivation from dominantly felsic upper continental crustal sources, whereas large variation of ε( t) and ε( t) values indicates that mantle-derived magmatic rocks also provided material to the sedimentary sequences in different degrees. The shift in ε( t) values of whole rocks and U-Pb age spectra of detrital zircons records the evolution from a back-arc to retro-arc foreland to a rift basin. Age distribution of detrital zircons from the Neoproterozoic sequences, compared with those of the major crustal blocks of Rodinia, implies that the position of the Yangtze Block was probably adjacent to northern India rather than between Australia and Laurentia before the breakup of the Rodinia supercontinent. [ABSTRACT FROM AUTHOR]

The article offers information on a study based on contemporary glacier systems of continental Eurasia. It mentions that continental Eurasia was distinguished into 32 regional glacier systems for the purpose of study including Karakorum range, Kunlun mountains and Nyangchentanglha. It adds that the "World Atlas of Snow and Ice Resources" depicting the maps of heights of equilibrium line and the regional glacier system regimes was used in the study for the determination of the feeding sources of distinguished regions. It mentions, the study reveals that area of glaciations has decreased in last 150 years.

C-isotope analysis of the carbonates in the Upper Neoproterozoic in Keping, Xinjiang indicates that the Qigebrak Formation and the Upper Sugaitbrak Formation mainly record positive C-isotope values, and a distinct positive excursion occurs in the lower part of the Qigebrak Formation. There are three negative excursions in the boundary between the Qigebrak Formation and the Cambrian, the uppermost and lowermost Upper Sugaitbrak Formation. These characters resemble those of the Upper Neoproterozoic in the Three-Gorge area, which suggests that the Upper Sugaitbrak Formation and Qigebrak Formation can be correlated with the middle and upper parts of the Doushantuo Formation and Dengying Formation, respectively. The negative excursion at the top of the Upper Sugaitbrak Formation corresponds to that at the top of the Doushantuo Formation, while the negative excursion at the bottom of the Sugaitbrak Formation can be correlated with that at the middle part of the Doushantuo Formation in the Three-Gorge area and that at the top of the Hangelchaok diamictites in the Quruqtagh area. [ABSTRACT FROM AUTHOR]

The Neoproterozoic Era witnessed two low-latitude glaciations, which exerted a fundamental influence on ocean–atmosphere redox conditions and biogeochemical cycling. Climate models and palaeobiological evidence support the belief that open waters provided oases for life that survived snowball Earth glaciations, yet independent geochemical evidence for marine redox conditions during the Marinoan glaciation remains scarce owing to the apparent lack of primary marine precipitates. In this study, we explore variability in rare earth elements (REEs) and trace metal concentrations in dolostone samples of the Cryogenian Nantuo Formation taken from a drill core in South China. Petrological evidence suggests that the dolostone in the Nantuo Formation was formed in near-shore waters. All the examined dolostone samples featured significant enrichment of manganese (345–10,890 ppm, average 3488 ppm) and middle rare earth elements (MREEs) (Bell Shape Index: 1.43–2.16, average 1.76) after being normalized to Post-Archean Australian Shale (PAAS). Most dolostone samples showed slight to no negative Ce anomalies (Ce*/Ce 0.53–1.30, average 0.95), as well as positive Eu anomalies (Eu*/Eu 1.77–3.28, average 1.95). This finding suggests that the dolostone samples were deposited from suboxic to iron-enriched and anoxic waters. Although total REE concentrations correlated positively with Th concentrations in dolostone samples, MREE-enriched PAAS-normalized patterns preclude the conclusion that REEs were largely introduced by terrestrial contamination. Rather, we interpret the correlation between REEs and Th as an indication that the former were transported by colloids and nanoparticles in meltwaters. Taken together, we propose that anoxic and ferruginous water columns dominated in South China during the Marinoan glaciation with a thin oxic/suboxic layer restricted to coastal waters. The extreme anoxic and ferruginous conditions prevailing in the Cryogenian would have provided a baseline for subsequent transient Ediacaran ocean oxygenation and life evolution. [ABSTRACT FROM AUTHOR]