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Sediment source-to-sink processes of river systems have significant impacts on depositional environments in coastal and shelf seas and on long-term climate change. Typically, sediments at the outlets of small mountainous rivers (SMRs) are considered to represent the average composition of particles eroded from the entire river basin due to the fast sediment transfer rate and short residence time in the basins. However, this assumption may be challenged by the significant heterogeneity in sediment erosion and transport processes within the SMRs catchments. In this study, we compare the geochemical and provenance heterogeneity of two typical mountainous rivers in subtropical East Asia, the Mulanxi in Mainland China and the Zhuoshuixi in Taiwan. These two SMRs have similar monsoon climate regimes but different tectonic, geomorphic, and hydrological settings, as well as sediment routing processes. Neodymium isotopes (εNd) and stable elemental ratios of Cr/Th and Sc/Th demonstrate the remarkable intra-catchment geochemical heterogeneity of both rivers. The εNd decreases from −7.1 to −10.0 from non-tidal to tidal reaches in the Mulanxi, while it changes from −11.5 in the upper reaches to −14.1 in the lower reaches of Zhuoshuixi. Apart from the general controls of provenance lithology and weathering processes on sediment geochemical heterogeneities between these two SMRs, the intra-catchment heterogeneity of the Zhuoshuixi is mainly induced by uneven sediment mixing in the flat and low connectivity areas (accounting for ∼36.5% of the downstream area). Meanwhile, the strong tidal influence is the primary control for the intra-catchment geochemical heterogeneity of the Mulanxi sediment, and relatively long sediment residence time in the catchment also plays some role. Our study suggests that samples collected at the river mouths cannot be simply treated as representative of the basin average or fluvial end-member to the sea. The compositional heterogeneity of the SMRs and its environmental effects and responses to rapid climate change require more in-depth investigations. • Distinct geochemical heterogeneity observed between SMRs in subtropical East Asia • Tide-induced sediment mixing accounts for heterogeneity of SMRs in SE China coast • Geomorphic features and climate events explain the heterogeneity of Taiwan rivers • Samples in the river mouth cannot represent the fluvial end-member to the sea [ABSTRACT FROM AUTHOR]

The hydrology of western Central Asia is highly sensitive to climatic perturbations. In order to understand its long-term variability and to infer linkages between precipitation and atmospheric and oceanic systems, we conducted a thorough sedimentary and geochemical study on a composite core retrieved in lake Son Kul (central Kyrgyzstan). A multi-proxy approach was conducted on lake sediments based on grain size analyses, magnetic susceptibility, total organic carbon (TOC), total nitrogen (TN) and carbon and oxygen isotope analyses on bulk and biogenic materials (ostracoda and molluscs shells) at a resolution equivalent to ca 40 years, aiming to characterise the sequence of palaeolimnological changes in Son Kul. As indicated by δ 18 O record of bulk carbonates, mainly consisting of aragonite, the Holocene hydrological balance was negative during most of time, suggesting an excess of evaporation (E) over precipitation (P). Limnological conditions fluctuated rapidly before 5000 cal yr BP indicating significant changes in regional hydrology and climate. In particular, the long-term negative hydrological balance was impeded by several short stages with marked increase of precipitation, lasting several decades to a few centuries (e.g., 8300–8200, 6900–6700, 6300–6100, 5500–5400, 5300–5200 and 3100–3000 cal yr BP). Precipitation changes as inferred from δ 18 O data are also documented by increased minerogenic detritus and higher TOC. We propose that the seasonal pattern of precipitation varied transiently in western Central Asia during the Holocene, although evaporation changes may also account for the rapid changes observed in δ 18 O data. When the annual water balance was less critical (P ≤ E), the excess of water might be ascribed to increased precipitation during cold seasons mainly because winter precipitation has more negative δ 18 O than its summer equivalent. Conversely, when the annual water balance is negative (P ≪ E), the moisture was mainly delivered during the warm season, as between 5000 and 2000 cal yr BP. Our results thus imply that moisture sources could have changed as well during the Holocene. Moisture was delivered as today mainly during summer from the extended Caspian-Aral Basin and eastern Mediterranean, although Arctic and even North Atlantic seas might be important moisture sources when seasonal precipitation was dominated by winter precipitation. We hypothesise that warming Arctic and North Atlantic seas were important for the North Hemisphere circulation during the cold season. [ABSTRACT FROM AUTHOR]

Abstract: We investigated mineral aerosol (dust) deposition in the Aral Sea with intention to understand the variability of dust in central Asia and its implications for atmospheric circulation change in the late Holocene. Using an 11.12-m sediment core of the lake, we calculated bulk sediment fluxes at high time-resolution and analyzed grain-size distributions of detrital sediments. A refined age-depth model was established by combined methods of radiocarbon dating and archeological evidence. Besides, a principal component analysis (PCA) of grain-size fractions and elements (Fe, Ti, K, Ca, Sr) was used to assess the potential processes controlling detrital inputs. The results suggest that two processes are mainly relevant for the clastic input as the medium silt fractions and Ti, Fe and K are positively correlated with Component 1 (C1), and the fine size fractions (<6 μm) are positively correlated with Component 2 (C2). Taking the results of the PCA, geological backgrounds, clastic input processes into account, we propose that the medium silt fractions and, in particular, the grain-size fraction ratio (6–32 μm/2–6 μm), can serve as indicators of the variability of airborne dust in the Aral Sea region. On the contrary, the fine size fractions appear to be contributed mainly by the sheetwash processes. The bulk sediment deposition fluxes were extremely high during the Little Ice Age (LIA; AD 1400–1780), which may be related to the increased dust deposition. As indicated by the variations of grain-size ratio and Ti, the history of dust deposition in central Asia can be divided into five distinct periods, with a remarkably low deposition during AD 1–350, a moderately high value from AD 350–720, a return to relatively low level between AD 720 and AD 1400 (including the Medieval Warm Period (MWP, AD 755–1070)), an exceptionally high deposition from AD 1400 to 1940s and an abnormally low value since 1940s. The temporal variations in the dust deposition are consistent with the changes in the Siberian High (SH) and mean atmospheric temperature of the northern hemisphere during the past 2000 years, with low/high annual temperature anomalies corresponding to high/low dust supplies in the Aral Sea sediments, respectively. The variations in the fine size fraction also show a broadly similarity to a lacustrine δ18O record in Turkey (), implying that there was less moisture entering western central Asia from the Mediterranean during the LIA than during the MWP. [Copyright &y& Elsevier]

Abstract: The Mangshan loess plateau is located 25 km to the west of Zhengzhou on the south bank of the Yellow River. Here the river flows out through the Sanmen Gorge releasing most of its suspended load following a dramatic decrease in gradient. The stratigraphy of the Mangshan loess deposits, consisting of a number of loess and palaeosol sequences, was established following magnetostratigraphic studies and measurements of magnetic susceptibility and grain size distribution. The Bruhnes/Matuyama boundary was found at the depth of about 130 m, indicating that this sequence at Mangshan resembles what is observed elsewhere in the Loess Plateau. The upper part of the Mangshan loess displays extremely high sedimentation rates (∼50 m3 per 1000 years), lower susceptibility values and coarser grain-size distribution, unlike the lower part of the profile and other sections in the Loess Plateau. This striking change indicates that the upper Mangshan loess had a different sediment source, different from the deserts that act as a common source for most of the loess deposits in central China. This sediment source is believed to be the proximal Yellow River floodplain, and the ancient alluvial fan lying at the eastern end of the Sanmen Gorge. The age estimation of the formation of the alluvial fan, based on Mangshan loess, suggests that the Yellow River may have eroded the Sanmen Gorge at approximately MIS 7. [Copyright &y& Elsevier]

Abstract: The Yecheng profile, lying in the southwest Tarim Basin at the northern foot of the West Kunlun Mountains, comprises 4.5 km of conformable Miocene to Pliocene strata. The lower part of the section, the Wuqia Group, is composed of interbedded red mudstone and pale-coloured fine sandstone with a thickness of 1700 m. The Artux Formation is 800 m thick and composed of mudstone, sandstone with thin gravel and conglomerate beds. The upper part of the section, known as the Xiyu Formation, consists of 2000 m of cobble and boulder conglomerate intercalated with massive siltstone lenses. Compositional study of the sandstones in the Wuqia Group and Artux Formation indicates that they were sourced from low relief areas of the Kunlun region and probably further south from Tibet. The provenance of the conglomerate in the Xiyu Formation is the West Kunlun Mountains. Compositional trends within the conglomerate indicate that Upper Palaeozoic marine, and Mesozoic to Tertiary terrestrial silicic rocks were eroded first, along with the Proterozoic to Lower Palaeozoic Proto-Tethys metasedimentary rocks. Erosion into deeper levels of the Kunlun Mountains provided igneous and high-grade metamorphic sediment, which first appears 640 m above the base of the Xiyu Formation. Lithofacies change from fine-grained mudstone and sandstone to coarse clasts coincides with the onset of aeolian sedimentation, indicating major shift of regional palaeoclimatic regime. Although climatic changes may have played an important role in controlling the sedimentary regime worldwide, our study of the lithostratigraphy and petrography of the Yecheng section suggests that the lithofacies change recorded the progressive unroofing history of the source rocks in the West Kunlun Mountains. [Copyright &y& Elsevier]

Detrital zircon U Pb geochronology and geochemical proxies derived from immobile elements and isotopes are commonly applied to trace sediment sources because of their durability and stability in most earth surface processes and environments. However, little is known on whether these different tracers can contain identical or similar provenance signals for sediments of interest. This study presents the U Pb ages of detrital zircons from a grain-size fraction of 63–125 μm and elemental and Nd isotopic compositions for bulk sediments from the Mulanxi, a small mountainous river in southeast China. We aim to retrieve provenance signals preserved by different tracers and to test whether they are robust in discriminating the effect of sediment mixing in this tidal-dominated river. Our results show that detrital zircons in the Mulanxi catchments and estuarine have two major age groups at 90–110 Ma and 120–150 Ma. Moreover, the results of probability density plots (PDPs) suggest there is no significant difference in detrital zircon U Pb ages between the sediments from non-tidal and tidal reaches. The detrital zircon age distributions in the Mulanxi catchments are significantly different from those in the Changjiang (Yangtze River) catchments and in the inner shelf mud belt of the East China Sea which have distinct multiple age populations. A statistical multidimensional scaling (MDS) analysis suggests there is no a source-to-sink connection between the Changjiang and Mulanxi zircons. On the contrary, the geochemical proxies of Sc/Th, Cr/Th, and Nd isotopes reveal different sediment sources between the non-tidal and tidal reaches of Mulanxi, with the fine tidal-reach sediments having mixed sources from the offshore mud and the Mulanxi River, while the coarse-grained sediments from the non-tidal upstream being completely contributed by the Mulanxi. The contradictory results from these different provenance proxies suggest their implications and limitations for sediment source tracing. Detrital zircon ages can track the 'inherited' source signals of zircons and relating coarse fractions in sediments, but they are less sensitive to source changes in fine fractions than the geochemical proxies of Nd isotopes, Sc/Th and Cr/Th ratios. It is therefore essential and a prerequisite to carefully evaluate all possible factors controlling detrital sediment compositions, and to weigh the pros and cons of different tracers for sediment provenance discrimination especially in dynamic Small Mountainous Rivers (SMRs) and continental margins. • We examine the sediment provenance signals carried by different geochemical proxies. • Immobile elemental ratios and Nd isotopes can discriminate the sediment mixing in the tidal dominated river. • Detrital zircon ages cannot indicate the source signals of bulk sediments. • Grain size effect and sedimentary recycling may bias the provenance indications of different proxies. [ABSTRACT FROM AUTHOR]

Linking marine sinks to potential terrestrial sources is one of most intriguing but challenging aspects of sediment source-to-sink studies. In this study, we analyzed 23 zircon samples (3271 filtered best ages) from surface sediments of the east China seas (ECSs) that cover a large portion of the Bohai Sea, Yellow Sea, East China Sea to part of the northeastern South China Sea. The results of U-Pb age distributions exhibit variable signatures in different seas. The Bohai Sea is characterized by 4 age populations at 203–286 Ma, 383–481 Ma, 1830–1940 Ma and 2480–2548 Ma, whereas the southern Yellow Sea and the East China Sea are featured by 5 age populations at 176–223 Ma, 383–481 Ma, 732–830 Ma, 1830–1940 Ma and 2480–2548 Ma. We propose that the presence or absence of the population of 732–830 Ma in the Yangtze Craton (YC) and the North China Craton (NCC) is a possible geochronological signature to distinguish zircon grains derived from the two source regions. Furthermore, on the basis of multidimensional scaling (MDS), U-Pb ages in the sediments of the Bohai Sea, East China Sea and the Taiwan Strait could be correspondently linked to those of the Yellow River, the Yangtze River and Taiwan rivers. The good linkages support the view that U-Pb age distributions of detrital zircons in the margin seas are mainly controlled by fluvial discharges, and ultimately, by the tectonic history of the corresponding source regions. Using a sediment forward mixing model, we obtained the relative sediment contributions and spatial variations of five most important river discharges in the region. The mixing results suggest that the major rivers in the region, i.e., the Yangtze and the Yellow Rivers, are the dominant sediment contributors to the continental margin, and their mixing coefficients could be used to infer relative sediment budgeting. In addition, spatial variations in mixing coefficient in the East China Sea indicate that sediment mixing and partitioning processes in the marine depositional environment have played a part role in propagating the provenance signals as a result of interaction of oceanic currents and tides. The combined method between provenance analysis and mixing modeling provides a feasible way to appreciate sediment budgeting in the geological past. [ABSTRACT FROM AUTHOR]

Objective: Trauma is a leading cause of death worldwide, with many incidents resulting in hemorrhage before the patient reaches the hospital. Despite advances in trauma care, the majority of deaths occur within the first three hours of hospital admission, offering a very limited window for effective intervention. Unfortunately, a significant increase in mortality from hemorrhagic trauma is primarily due to delays in hemorrhage control. Therefore, we propose a machine learning model to predict the need for urgent hemorrhage intervention. Methods: This study developed and validated an XGBoost-based machine learning model using data from the National Trauma Data Bank (NTDB) from 2017 to 2019. It focuses on demographic and clinical data from the initial hours following trauma for model training and validation, aiming to predict whether trauma patients require urgent hemorrhage intervention. Results: The XGBoost model demonstrated superior performance across multiple datasets, achieving an AUROC of 0.872 on the training set, 0.869 on the internal validation set, and 0.875 on the external validation set. The model also showed high sensitivity (77.8% on the external validation set) and specificity (82.1% on the external validation set), with an accuracy exceeding 81% across all datasets, highlighting its high reliability for clinical applications. Conclusions: Our study shows that the XGBoost model effectively predicts urgent hemorrhage interventions using data from the National Trauma Data Bank (NTDB). It outperforms other machine learning algorithms in accuracy and robustness across various datasets. These results highlight machine learning's potential to improve emergency responses and decision-making in trauma care. [ABSTRACT FROM AUTHOR]

• Climate controlled wildfires in the Changjiang River Basin before the mid-Holocene. • Enhancing human activities induced the fire regime shift since ∼ 5 ka. • Farming and bronze smelting promoted natural landscape changes by fire use. Deforestation and technical innovation have changed the natural fire regimes, topography and carbon reservoirs during the history of human evolution. Recognition of the timing, scope, and magnitude of wildfire events in large river basins such as the Changjiang (Yangtze River) is essential for understanding the impacts of climate forcing and human perturbation on Earth surface processes. Here, we present a multi-proxy study based on the pollen and black carbon (BC) abundance in sediments of Core CM97 taken from the Changjiang Delta, aiming to reconstruct the paleo-fire history in the Changjiang River Basin and further disentangle anthropogenic and climatic influences on fire regimes during the Holocene. Our results show that the average BC abundance increased from 0.88 ‰ at 12–8 cal kyr BP to 1.17 ‰ at 8–5 cal kyr BP, well corresponding to the evolution of the Asian Summer Monsoon (ASM). This suggests the wildfire occurrences were dominated by hydroclimatic conditions during 12–5 cal kyr BP. After the early Bronze Age (∼5 cal kyr BP), the sustained high anomaly of BC abundance (average 1.30 ‰), however, was decoupled from the weakened monsoon climate. We propose that this might be associated with anthropogenic destruction of natural forests through fire-assisted agriculture and bronze smelting. Especially, with the prosperity of the Han Dynasty (202 BCE − 220 CE), a rapid increase in population promoted the transition of ecosystem (vegetation type) from forests to permanent farmlands in the drainage basin. Human intervention has overwhelmed the long-term climate control over wildfire, plant diversity, soil erosion, and sediment source-to-sink processes, suggesting the dominance of anthropogenic activities on nature over the last 2 kyrs. Our study provides deep insight on the enhancing perturbation of human activities on Earth's surface at a continental scale and provides more constraints on the Anthropocene epoch. [ABSTRACT FROM AUTHOR]

The Yangtze (Changjiang) Delta serves as a prominent depocenter for siliciclastic sediments from the Tibetan Plateau and Yangtze Craton, providing essential data on sediment source-to-sink dynamics and geomorphological evolution of large river drainage systems. This study presents the detrital zircon geochronology of Plio–Pleistocene sediments in the Yangtze Delta, alongside the data from modern river sediments, to elucidate provenance evolution since the Pliocene. The zircon geochronology reveals a considerable shift in sediment provenance during the Pliocene–Pleistocene transition. The Pliocene sediments exhibit a straightforward and predominant zircon age spectrum characterized by a typical peak age of 100–200 Ma. This spectrum markedly differs from the modern upper–middle Yangtze River sediments but closely resembles those of local rivers in the lower Yangtze River region. This demonstrates that the Pliocene sediments originated from local mountainous rivers, indicating the paleo-Yangtze River channelization prior to the Quaternary. In contrast, the zircon age spectra of Pleistocene sediments in the present-day delta reveal several dominant age groups ranging from 11.9 ± 1 to 3643 ± 30 Ma, similar to those found in present-day upper–middle Yangtze River sediments. This implies that the Pleistocene sediments were mainly derived from the upper–middle Yangtze River, showing a diversity of source rocks with varying geological ages and origins. The presence of the upper Yangtze River provenance signal, characterized by Cenozoic (<65 Ma) zircons, in early Pleistocene strata (ca. 1.6 Ma) of the delta suggests that the paleo-Yangtze River transported Tibet-sourced sediments into the modern delta area no later than that time. These findings indicate the geomorphological evolution of the Yangtze River Delta from an intermontane basin in the Pliocene to an alluvial–fluvial plain during the Quaternary. This geomorphological and geographic evolution, along with changes in sediment source, directly reflect extensive tectonic subsidence in eastern China since the late Cenozoic. • The Pliocene sediments of Yangtze River Delta differ markedly from modern Yangtze-, but closely resembles those from local regions. • At the initial Quaternary, middle-upper Yangtze River sediment had arrived in northern Yangtze River Delta area. • The paleo-Yangtze River delivered the Tibet-sourced sediments into the modern delta no later than ca.1.6 Ma. [ABSTRACT FROM AUTHOR]

Silicate weathering has long been considered to maintain the Earth's climate stability, yet how the weathering responds to the late Cenozoic cooling remains unclear, partly because of the complicated factors which obscure the weathering records. Large rivers in East Asia integrate continental weathering history, but how the source-to-sink system evolution affected the weathering signals need to be clarified. We compile proxy data of Nd isotopes, zircon ages and Chemical Index of Alteration (CIA) in East Asian margin and source terranes, along with new proxy data from core CSDP-2 in the shelf region, to understand the large river evolution and assess their influence on weathering proxy records. The median εNd values of East Asian marginal sediments increased from −18.8 in pre-3.6 Ma period to −11.3 since the 1.0 Ma, corresponding to the isotopic signatures in North China Craton and Northeastern (NE) Tibetan Plateau/Loess Plateau terranes, respectively. The zircon ages further confirmed the provenance shift, hinting that the modern-like Huanghe (Yellow River) system has been fully integrated during early Pleistocene, no later than ∼1.0 Ma. This integration facilitated the sediment transportation from plateaus into the continental margin. Consequently, the CIA records in marginal regions show a more significant decrease than other Asian regions, within the context of Plio-Pleistocene cooling. Our study found that the upland expansion of large river system and global cooling jointly controlled the decline in the weathering intensity records, highlighting the importance to understand the evolution of source-to-sink system before interpreting the weathering signals from the continental margin sediments. • Detrital Nd isotopes and zircon ages are compiled to constrain the sediment sources in East Asian margin. • The sediment provenance shifted from proximal lowlands to uplands, links to the Huanghe integration. • Large river expansion in East Asia amplified the decline in weathering intensity proxy records since the Pliocene. [ABSTRACT FROM AUTHOR]

The terrigenous sediment source-to-sink processes in continental margins are determined by complex interactions among climate, sediment discharge, sea level and oceanic circulations on various temporal and spatial scales. The northeastern South China Sea (NSCS) margin is a natural laboratory to catch a glimpse of these processes due to large amounts of terrigenous sediment inputs and continuous sedimentations during the late Quaternary. Based on a 35 m-long sedimentary sequence (core MD12-3429) retrieved from the NSCS upper continental slope, we distinguished sediment sources based on geochemical compositions, and then linked sedimentary responses to sea level change and Kuroshio intrusion over the past 244 kyrs via various sedimentary records including mass accumulation rates (MAR), foraminifera data, grain-size end-member modeling (EMM) and spectral analysis. Geochemical proxies including major element ratios and fractionation parameters of rare earth elements suggest that the detrital sediment in the core was derived primarily from the Taiwan. The MAR of terrigenous sediment yields an average 9.6 g/cm2/kyr, and high MAR values are both observed in glacial and interglacial intervals. The results of EMM reveal three end-members with dominant modal grain sizes of 6.6 μm (EM1), 26.3 μm (EM2) and 49 μm (EM3), respectively. The temporal variations of the finest end-member (EM1) and the coarsest end-member (EM3) demonstrate clearly glacial-interglacial cyclicity, and the spectral analysis indicates the dominance of 100-kyr eccentricity, which suggests that sea level changes are the first-order control for the NSCS continental margin sedimentation. In addition, the temporal variations in hydrodynamic sensitive component (EM2) and its MAR display gradually increasing trends with weakening East Asian monsoon. Combing with modern observation and modeling results, we suggest that enhanced Kuroshio intrusion might account for the transport of Taiwan-derived sediment during the late Quaternary. As indicated by a 31 kyr periodicity in EM2, we infer that the development of El Niño-like condition strengthened the intrusion of oligotrophic Kuroshio from the Luzon Strait, resulting in the obvious increase of Taiwan terrigenous MAR but decreases of the primary productivity in the northeastern South China Sea. This study provides deep insight into the complex terrigenous sediment source-to-sink processes in a fast-changing marginal sea environment during the late Quaternary. • Sea-level change was the primary control for terrigenous sediment source-to-sink processes in the NSCS since MIS7. • Strengthened intrusion of Kuroshio dominated Taiwan sediments transport. • Kuroshio intrusion and ENSO forcing were coupled on glacial-interglacial scale. • Grain size end-member modeling provides insights into sedimentary response to changes of sea level and oceanic circulation. [ABSTRACT FROM AUTHOR]

Abstract: River bed sediments were collected from the main stream and major tributaries of the Yangtze River for clay mineralogy study. Surface sediments from the Yarlung Zangbo River on the Tibetan Plateau were also examined for comparison. The results show that the clay mineral compositions of the Yangtze River display a similar pattern through the whole truck stream, with illite being dominant, kaolinite and chlorite being lesser abundant, and smectite being minor component. Clay mineralogy shows distinct differences in the tributaries, which correspond to the heterogeneous source rocks and weathering intensity of the drainage. The illite crystallity and the illite chemical weathering index (5Å/10Å peak ratio) both increase downstream, indicating a increasing trend of hydrolysis along the river. It also indicates that the upperstream of the drainage is characterized with physical weathering while the middle- and lower reaches are controlled by chemical weathering process. In accordance with the result derived by the illite indexes, sediment input from upperstream including Yalong Jiang, Dadu He, Min Jiang and Jialing Jiang accounts for the major sediment load, whereas Wu Jiang, Xiang Jiang, Gan Jiang and Dongting Lake provide relatively less sediments. [Copyright &y& Elsevier]

Detrital zircon grains of Late Cenozoic sediments dated back to ca. 3.6 Ma from core DY03 in the Yangtze delta were dated by LA-ICP-MS, in order to investigate the sedimentary provenance and to find some clue for the evolution of the Yangtze River. Most of the detrital zircon U-Pb ages are distributed at 100-300 Ma, 350-550 Ma, 600-1000 Ma, 1400-2000 Ma and 2200-2800 Ma, which correspond well with the main tectonic and magmatic events in the Yangtze drainage. The detrital zircon age patterns show distinct difference between the 3 samples below 189.8 m and other 6 above 189.8 m. 43%-55% zircons in the 3 samples below 189.8 m fall within Cretaceous, while ages from 150 to 2800 Ma are distributed with no obvious peaks, which indicate the sedimentary provenance may be limited to the lower Yangtze drainage. The 6 samples above 189.8 m show similar age patterns, and the ages are relatively evenly distributed, indicating the sedimentary provenance broadened distinctly. All 6 samples deposited later than ca. 3.2 Ma show age information from the upper Yangtze drainage (including the Emeishan large igneous province), indicating that the Three Gorges may have already been cut through by then. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt is complex and little understood in its geotectonic history. Here, we apply a new approach to conclude on the paleogeography of major Mongolian terrains using small skeletal fossil assemblages and a combined analysis of U‐Pb ages and typology of detrital zircons. We document a new Cambrian Stage 3 fauna from the Telmen Block located between the Dzhabkan and Tuva‐Mongolia cratons. Based on a hierarchical cluster analysis of 35 blocks, we observe the most robust biogeographic relationship between Telmen and Kusnetzk Alatau and between Tuva‐ Mongolia and Lake Zone. These results challenge the view that these cratons were assembled during the Ediacaran/Cambrian in a single ribbon‐shaped paleocontinent. Detrital zircon U‐Pb ages indicate a unique age population at ∼516 Ma at Telmen derived from I‐type granitoids, neither seen on Dzhabkan nor Tuva‐Mongolia cratons supporting their different tectonic evolution within the Palasian Ocean after the breakup of Rodinia. Plain Language Summary: The Central Asian Orogenic Belt is the largest orogeny on Earth, with main orogenetic events spanning the late Cambrian to early Triassic (ca. 500–250 Ma) reaching from the Ural Mountains to the Pacific Ocean. It included many Proterozoic Terrains, part of which are situated in Mongolia. However, until now, little is known about the pre‐orogenic paleogeographic settings of these terrains. Here we investigated detrital zircon age populations and biogeographic relationships of small skeletal fossils of the Cambrian cover strata to conclude on the pre‐orogenic tectonic evolution of the terrains. U‐Pb ages of detrital zircons allowed us to compare age histograms of different blocks and draw interpretations of their source rocks. Studying the mineralized skeletal remains of various metazoan groups concludes their paleobiogeographic relationships within the Mongolian micro blocks. In particular, the Telmen Block provides new insights challenging the previous hypotheses on the existence of one large ribbon‐shaped continent before the onset of the orogeny. This study instead argues for individual tectonic and metazoan evolution pathways of early Cambrian Mongolian blocks after the breakup of the supercontinent Rodinia. Key Points: Novel reconstruction tool for paleogeography of Mongolian Central Asian Orogenic Belt terrains using detrital zircon age provenance and small skeletal fossilsRewriting the long‐held theory that the Mongolian terrains formed a single ribbon‐shaped continent during the Ediacaran/CambrianZircon provenance and small skeletal fossils biogeography argue for individual tectonic evolution of Mongolian terrains from Ediacaran to early Cambrian [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt is complex and little understood in its geotectonic history. Here, we apply a new approach to conclude on the paleogeography of major Mongolian terrains using small skeletal fossil assemblages and a combined analysis of U‐Pb ages and typology of detrital zircons. We document a new Cambrian Stage 3 fauna from the Telmen Block located between the Dzhabkan and Tuva‐Mongolia cratons. Based on a hierarchical cluster analysis of 35 blocks, we observe the most robust biogeographic relationship between Telmen and Kusnetzk Alatau and between Tuva‐ Mongolia and Lake Zone. These results challenge the view that these cratons were assembled during the Ediacaran/Cambrian in a single ribbon‐shaped paleocontinent. Detrital zircon U‐Pb ages indicate a unique age population at ∼516 Ma at Telmen derived from I‐type granitoids, neither seen on Dzhabkan nor Tuva‐Mongolia cratons supporting their different tectonic evolution within the Palasian Ocean after the breakup of Rodinia. Plain Language Summary: The Central Asian Orogenic Belt is the largest orogeny on Earth, with main orogenetic events spanning the late Cambrian to early Triassic (ca. 500–250 Ma) reaching from the Ural Mountains to the Pacific Ocean. It included many Proterozoic Terrains, part of which are situated in Mongolia. However, until now, little is known about the pre‐orogenic paleogeographic settings of these terrains. Here we investigated detrital zircon age populations and biogeographic relationships of small skeletal fossils of the Cambrian cover strata to conclude on the pre‐orogenic tectonic evolution of the terrains. U‐Pb ages of detrital zircons allowed us to compare age histograms of different blocks and draw interpretations of their source rocks. Studying the mineralized skeletal remains of various metazoan groups concludes their paleobiogeographic relationships within the Mongolian micro blocks. In particular, the Telmen Block provides new insights challenging the previous hypotheses on the existence of one large ribbon‐shaped continent before the onset of the orogeny. This study instead argues for individual tectonic and metazoan evolution pathways of early Cambrian Mongolian blocks after the breakup of the supercontinent Rodinia. Key Points: Novel reconstruction tool for paleogeography of Mongolian Central Asian Orogenic Belt terrains using detrital zircon age provenance and small skeletal fossilsRewriting the long‐held theory that the Mongolian terrains formed a single ribbon‐shaped continent during the Ediacaran/CambrianZircon provenance and small skeletal fossils biogeography argue for individual tectonic evolution of Mongolian terrains from Ediacaran to early Cambrian [ABSTRACT FROM AUTHOR]

Abstract We examined the spatial and vertical distribution of total mercury (THg) in 119 surface sediment samples and 4 sediment cores from the coastal East China Sea. The THg concentrations (3.6–69.2 μg kg−1, average 34.7 μg kg−1) in surface sediments exhibited a decreasing trend from the inner shelf towards the outer shelf. The THg levels in sediment cores showed a significant increasing trend from the bottom to the top layer. Both the spatial and vertical distribution of THg indicates the impacts of anthropogenic inputs. The THg concentrations in the surface sediments of Yangtze River estuary were strongly correlated with sediment particle size and organic matter, governing by the Yangtze River inputs. The relatively higher THg levels in the surface sediments of southern inner shelf were attributed to the stronger binding affinity of the finer-grained sediments, the nature of organic matter, as well as local inputs. The spatial distribution of toxic methylmercury (MeHg) was distinct from THg, controlled by direct terrigenous MeHg inputs and in situ MeHg formation. The net Hg methylation potential (indicated by MeHg/THg ratio) in surface sediments were significantly influenced by both geochemical factors (DO, temperature and water depth) and the physicochemical properties of sediments (grain size, TOC, S, Fe 2 O 3 and MnO), and exhibited the highest correlation with TOC, suggesting the key role of organic matter in governing net MeHg production. Moreover, sites with high MeHg/THg ratios mainly occurred within the summer hypoxia zones adjacent to the Yangtze River estuary, suggesting special attention on Hg ecological risks should be paid in this region. Graphical abstract Unlabelled Image Highlights • Sediments THg distribution in East China Sea (ECS) indicates anthropogenic inputs. • Organic matter and sediment grain size control the spatial distribution of THg. • Terrigenous inputs and in situ MeHg formation control the MeHg spatial distribution. • Organic matter plays key role in governing Hg methylation potential in the ECS. • Sites with high methylation potential mainly occurred in the summer hypoxia zones. [ABSTRACT FROM AUTHOR]

Abstract We have examined the possible use of Mn/Ca ratios in benthic foraminifera as a proxy for hypoxia, which has increasingly become a serious environmental issue in many coastal zones. We collected samples from the Yangtze River Estuary, one of the largest and most intense seasonally hypoxic zones in the world. In order to obtain high quality Mn/Ca data, unaffected by contamination, we examined two different cleaning protocols and instrument-based analysis methods. Our results showed that a relatively simple physical cleaning approach coupled to laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) provided excellent results on single specimens. Our observations were comparable to ICP analyses of solutions made up from dozens or even hundreds of specimens and involving complicated sample pretreatments. Using the LA methodology, we analyzed Mn/Ca ratios from living Florilus decorus (F. decorus) specimens from stations in the Yangtze River Estuary with varying bottom water dissolved oxygen (DO) concentrations. Our results showed that Mn/Ca ratios in penultimate chambers of living benthic foraminifera are sensitive to bottom water DO concentrations. We also observed significant variations of both Mn/Ca and Mg/Ca ratios from different chambers within foraminiferal shell specimens. These fluctuations were likely a response to changing ambient water DO and temperature during the specimen's growth history. Combined use of foraminiferal Mn/Ca ratios together with other proxies could provide a powerful tool for historical reconstruction of low oxygen conditions in seasonal hypoxia areas. [ABSTRACT FROM AUTHOR]

Chemical speciation of iron (Fe) in sediment offers a better understanding on iron cycle, early diagenesis, paleoredox condition and paleoclimatic changes. This study reports the Fe chemical speciation (total concentration Fe T , highly reactive Fe HR , poorly reactive Fe PR and unreactive Fe U ) in the surface sediments from the Changjiang (Yangtze River) Estuary and the East China Sea shelf. The Fe HR concentrations in the estuarine and shelf sediments are much lower than those from the Changjiang and other rivers in the world, confirming the previous observations on geochemical fractionation effect in estuarine and shelf sediments. The high correlations of Fe HR with Fe T and Al concentrations and sediment surface area, suggest the dominance of clay minerals on Fe HR composition in the sediments. The apparent enrichments of Fe HR , total organic carbon and surface area in the hypoxia zone off the Changjiang Estuary are primarily caused by the local hydrodynamics and sedimentary processes. Despite the wide application of Fe HR /Fe T ratio for redox condition, its spatial distribution from the Changjiang river mouth to open shelf reveals no obvious enrichment in the hypoxia zone. This suggests that the episodic occurrence of hypoxia off the Changjiang Estuary (mostly in August) is hardly imprinted in particulate iron speciation. The distributions of Fe chemical speciation along the “river-estuary-open shelf” transect suggest the complex controls of particulate iron “shuttle transport” and deposition in the continental margin where fluvial input dominates and intense anthropogenic impact exists. Our study sheds new light on the source-to-sink process of particulate iron in the estuary and open shelf, and also provides important constraints of Fe speciation in modern and ancient archives from various depositional environments. [ABSTRACT FROM AUTHOR]

• River sediments in the eastern and western Fujian have distinct source rock compositions. • Indosinian magmatic rocks predominantly originated from the Proterozoic crust. • Yanshanian magmatic rocks originated from both the DM (Depleted Mantle) and Proterozoic crust. • The middle Zhenghe-Dabu Fault predominantly account for geochemical heterogeneity of river sediments. The Cathaysia Block is featured by intense tectonic activities and magmatic intrusions during the Mesozoic, and its geochemical evolution might greatly imprint the river sediment compositions in southeast China. This paper presents a comprehensive synthesis of data from petrology, U-Pb geochronology, and geochemistry of both river sediments and plutons in Fujian Province, and aims to reveal the constraints of Mesozoic geochemical heterogeneity and geochronology of the Northeast Cathaysia Block on local river sediment geochemistry. The Fujian terrane and relating river systems can be divided into western and eastern parts with the boundary of the Zhenghe-Dabu Fault. The sediments of eastern rivers are characterized by heavy minerals derived from granites and two major U-Pb age groups (90–110 Ma and 120–150 Ma) of detrital zircons. However, the sediments of western rivers are featured by heavy minerals from the Precambrian rocks and have seven zircon U-Pb age groups (from 90 Ma to 3.0 Ga). The Indonesian magmatic rocks predominantly originated from the Proterozoic crust, with less contribution from the depleted mantle, which are much different from the Yanshanian A-type granites and gabbros in the eastern terrane. We infer that the middle part of Zhenghe-Dabu Fault formed in the Jingningian Period primarily caused geochemical and geochronological heterogeneity of the Northeast Cathaysia Block, which further determined the totally different sediment compositions between the western and eastern Fujian rivers. [ABSTRACT FROM AUTHOR]

The Late Triassic was a key period for the evolution of the western Sichuan Basin from marine to continental sedimentation. However, the provenance of the earliest terrigenous sediments during this period remains debated, hindering our understanding of the tectonic events that ruled the evolution of the basin at that time. Herein, samples of fine sandstone from the Upper Triassic Ma'antang and Xiaotangzi formations in the western Sichuan Basin were collected for petrology, heavy mineral analysis, bulk rock geochemistry, and detrital U–Pb dating. In addition, corresponding data from potential source areas were collected for comparison. The sedimentological, geochronological, and geochemical characteristics of terrigenous sediments suggest that the clastic materials were mainly sourced from the Qinling orogenic belt and Yangtze Craton (including the northern and western margin). The Longmen Shan thrust belt likely provided clastics since the Early Norian. Siliciclastic deposits of the Late Triassic sedimentary succession of the western Sichuan Basin (Ma'antang and Xiaotangzi formations) yielded young zircon U–Pb ages of 214–245 Ma, suggesting that these zircons were likely sourced from the magmatic activities in the South Qinling orogenic belt or Yidun Island Arc. Combined with previous research, this study predates the transformation of the western Sichuan Basin from marine to continental sedimentation in the Late Carnian/Early Norian period. • The terrigenous clastics of the western Sichuan Basin first appeared in the Ma'antang during the Late Carian period. • The terrigenous clastics possibly derived from the Qinling Orogenic Belts, Yangtze Craton and its marginal blocks. • Since the deposition of the Xiaotangzi Fm., the Longmenshan thrust belt provided clastics for the Western Sichuan Basin. • The young volcanic zircons (214∼245Ma) were probably sourced from the South Qinling orogenic belt or Yidun Island Arc. [ABSTRACT FROM AUTHOR]

In recent years, herbaceous species such as Deyeuxia angustifolia (Kom.) Y. L. Chang has invaded alpine tundra regions of the western slope of the Changbai Mountains. Because atmospheric nitrogen deposition is predicted to increase under a warming climate and D. angustifolia is sensitive to nitrogen addition, field experiments were conducted from 2010 to 2013 to determine the effect of increased nitrogen deposition on the mechanisms of D. angustifolia invasion. The goal of this study is to evaluate the impact of increased nitrogen deposition on the changes in alpine tundra vegetation (consisting mostly of Rhododendron chrysanthum Pall. and Vaccinium uliginosum Linn.). The results showed that: 1) simulated nitrogen deposition affected overall characteristics and structure of R. chrysanthum and V. uliginosum communities and had a positive impact on the growth of tundra vegetation invaded by D. angustifolia; 2) R. chrysanthum was more resistant to invasion by D. angustifolia than V. uliginosum; 3) simulated nitrogen deposition could improve the growth and enhance the competitiveness of D. angustifolia, which was gradually replacing R. chrysanthum and V. uliginosum and might become the dominant species in the system in future, transforming alpine tundra into alpine meadow in the Changbai Mountains. [ABSTRACT FROM AUTHOR]

In this paper, sea-level fluctuations during the Carnian Pluvial Episode (CPE) are investigated. A revision of published data from multiple successions worldwide indicates a sea-level drop that occurred in different geodynamic settings after the onset of the first of multiple carbon-isotope perturbations that characterize the CPE. New stable isotope data, zircon U-Pb geochronology, carbonate petrology, conodont and foraminifer biostratigraphy from the Carnian of the Sichuan Basin and comparison to the well-dated coeval successions of the Dolomites allow pinpointing with unprecedented precision this sea-level fall and determine that it occurred after the onset of the first, but prior to the third negative δ 13 C shift of the CPE. These lines of evidence indicate that such sea-level oscillation was eustatic. Facies analysis and sequence stratigraphy of units deposited during the ensuing sea-level rise in the Sichuan and Dolomites, further show that a Tethys-wide crisis of microbial carbonate production and drowning of carbonate platforms were followed by a recovery of marine calcification, widely testified by the deposition of oolitic bodies. Whereas a Tethys-wide recovery of microbial carbonate production is documented at the end of the Carnian, this increase in chemical calcification occurred earlier, at the beginning of the Tuvalian, and suggest that global transformations in carbonate systems coincident with the CPE were complex and share commonalities with other times in the geological record when a similar evolution was linked to ocean acidification. • New bio-, chrono-, chemostratigraphic and sedimentological data on the CPE. • Tethys wide correlation of carbonate platform successions across the CPE. • Correlations and sequence stratigraphy highlight an eustatic sea-level fall. • Results suggest global fluctuations in carbonate production during the CPE. [ABSTRACT FROM AUTHOR]

A multiproxy study was conducted on Holocene sediments from the alpine lake Son Kul (3010 m a.s.l, 41°48′33N/75°07′38E) in central Tien Shan (Kyrgyzstan). The combination of high-resolution pollen, palynofacies and magnetic susceptibility data allowed reconstruction of changes in sedimentary and vegetation dynamics regionally at Son Kul between 8350 and ca 2000 cal. BP. Using pollen data to quantify climatic parameters, a quantitative reconstruction of climatic conditions was performed using the “Modern Analogue Vegetation types” (MAV) method and a ranged index of seasonality. The most temperate (e.g. moister) climate conditions occurred between 8350 and 5000–4500 cal. BP when alpine meadow vegetation was enriched in plants requiring moister conditions and trees developed regionally. Conversely, more continental and arid conditions prevailed after 4500 cal. BP with the decline of arboreal vegetation (especially Juniperus) and the extension of an alpine steppe-meadow along with a regional decrease in Poaceae. This climate transition was associated with a change in seasonality as the continentality greatly intensified after 5000–4500 cal. BP. Our results are consistent with other records from the Tien Shan range and the Chinese Province Xinjiang showing that relatively wet conditions prevailed regionally before 5000 cal. BP, whereas reduced moisture conditions were established after that time. From a more global perspective, we highlight that regional rainfall in central Tien Shan and western Central Asia is likely to be predominantly controlled by the Eastern Mediterranean cyclonic system and North Atlantic climate, as based on the close correspondence between climatic archives from western Central Asia, the Levant, the Eastern Mediterranean and Caspian Sea regions. However, the effect of monsoonal dynamics on the regional climatic system in central Tien Shan still remains dubious, since recent modelling studies have shown that no dynamic link exists between humidity in Central Asia and the Indian Summer Monsoon. This study pinpoints the need to explore the effect of remote Eurasian atmospheric circulation patterns on past climate variability in Central Asia. [ABSTRACT FROM AUTHOR]

• C, Sr, Nd and trace element chemostratigraphy of Neoproterozoic Witvlei Group carbonates. • Zircon provenance of Witvlei Basin sandstones is comparable with nearby Ghanzi Group tracing erosion of the Kalahari Craton. • Variable weathering fluxes and ocean circulation patterns affecting post-glacial seawater. • Putative Shuram anomaly equivalent coincides with a decrease in bio-essential trace metals and less oxidised surface waters. • Bio-essential and redox-sensitive trace element enrichments in late Ediacaran seawater similar to the Phanerozoic. The Neoproterozoic witnessed several low latitude glaciations (i.e., the Sturtian, Marinoan and Gaskiers glaciations) and the geodynamic reorganization of cratonic blocks after the breakup of Rodinia. Trace element and stable isotope geochemistry from approximately coeval carbonate deposits on continental marginal sea and foreland basins (Yangtze Platform, China; Otavi and Nama Groups, Namibia) have shown fluctuating oxygen increase on the marine shelves. To gain an increasingly global picture of the bio-geochemical conditions in late Neoproterozoic seawater, we here present new redox-sensitive trace element, stable (C, O) and radiogenic (Nd, Sr) isotope records of carbonates from the Cryogenian Blaubeker and Court, and the Ediacaran Buschmannsklippe Formations (Witvlei Group, Namibia). Shale-normalised REE + Y patterns of post-Sturtian and post-Marinoan carbonates parallel modern seawater showing positive La, Gd and Y anomalies. Negative Ce anomalies argue for their preservation in increasingly more oxidising sea/porewater conditions in the Witvlei Basin from the Ediacaran on. While Cryogenian carbonates underwent radiogenic basin-fluid type overprinting, Ediacaran carbonates upsection record pristine Sr isotopic compositions that match the global Neoproterozoic seawater curve. Partly coupled negative correlations between Sr and Nd suggest long-term shifts in continental weathering and short-term changes in ocean circulation patterns. The δ13C carb values range from −7.2 to +3.5 ‰ and record a negative isotope excursion in the upper part of the Witvlei stratigraphy. This excursion might be equivalent to the 'Shuram' carbon isotope excursion (CIE). However, the causes, global extent and correlation of the Shuram CIE are still debated. Typical for carbonates of the putative Shuram excursion are less pronounced Ce anomalies, lower Y/Ho ratios, and lower bio-essential and redox-sensitive trace metal concentrations, arguing for periodic redoxcline oscillations in a redox-stratified late Neoproterozoic shelf environment. The overall long-term decrease in redox-sensitive element enrichments throughout the Witvlei Group argues for a progressively increasing, presumably biologically-driven metal cycling towards values typical for Phanerozoic carbonates. The combination of changes in local weathering flux and ambient redox conditions in the late Neoproterozoic ocean may have caused dynamic (bio)geochemical metal cycling, predating (and possibly promoting) the metazoan radiation documented in the overlying Nama Group. [ABSTRACT FROM AUTHOR]

• Silicate weathering intensity was enhanced during the Pliocene and weakened during the Quaternary. • Response of weathering intensity to temperature in Southeast Asia since the Pliocene is consistent with modern observations. • Amplified weathering response to cooling climate in East Asia relates to midlatitude cooling, provenance and weathering regime shifts. • First observation on silicate weathering response to temperature change at various latitudes in geological past. Silicate weathering plays a key role in maintaining a habitable climate on Earth. Although the climate-weathering link has been verified by observations on river geochemistry and weathering profiles, it remains a big challenge to quantify this link in the geological past mainly because sedimentary records of weathering intensity are complicated by other factors such as tectonics, sediment provenance and sorting effects. To clarify the climate dependence of weathering on different spatial and temporal scales, 4 Myr weathering intensity records determined by Chemical Index of Alteration (CIA), are compiled from 12 sites along the East and Southeast Asian margins ranging from ca. 10°N to 40°N. All the CIA records show overall decreasing trends, corresponding to global cooling. The CIA stacks that indicate regional and continental-scale weathering intensity are produced by binning and averaging the CIA data from each site. To explore the weathering intensity-temperature relationship, literature data on sea surface temperature (SST) anomaly are presented for the paleo-temperature changes at comparable latitudes. The results show that the decrease in CIA stack since 4 Ma is larger in East Asia (71-82 in Pliocene down to ca. 62 in late Quaternary) than in Southeast Asia (73-75 in Pliocene to ca. 72 in late Quaternary), in part due to the amplified midlatitude cooling. The correlation analyses indicate the temperature sensitivity of stacked CIA record in Southeast Asia (ca. 0.8 CIA units/°C) is consistent with modern observations of surface soils and river sediments. In comparison, the response of weathering intensity to temperature change is more sensitive in East Asia, with a magnitude of ca. 2.4 CIA units/°C, which may relate to dynamic source-to-sink processes and weathering regime changes. This study provides the first observation on silicate weathering responses to temperature changes at various latitudes since the Pliocene, showing the similar responses, but with different magnitudes. Our findings provide new insights on continental weathering mechanism and late Cenozoic cooling. [ABSTRACT FROM AUTHOR]

Upper Triassic deposits formed at the onset of subsidence in the Sichuan foreland basin of South China, and may record a crisis of carbonate deposition related to the Carnian Pluvial Episode. However, there is no consensus yet on the precise age of these deposits in northwestern Sichuan. In this work, ammonoid biostratigraphy has been improved, and a U/Pb age from detrital zircons has been obtained from the Upper Triassic of northwestern Sichuan. New ammonoid taxa Sinotropites sichuanensis n. gen., n. sp. and Hadrothisbites hanwangensis n. sp. are described from the upper part of the Ma'antang Formation in Hanwang and Jushui area and are assigned to the uppermost Tuvalian (Anatropites spinosus Zone, Gonionotites italicus Subzone). Ammonoid and conodont biostratigraphy, combined with U/Pb concordant ages of 227.2 ± 1.1 Ma obtained from youngest detrital zircons, provide a robust constrain on the initial sedimentation phases of the foreland basin in northwestern Sichuan, and suggest that the terrigenous turnover was not related to the Carnian Pluvial Episode. • We report a U/Pb age of 227.2 ± 1.1 Ma associated with ammonoids in South China. • Sinotropites sichuanensis and Hadrothisbites jushuiensis are described in Sichuan. • The terrigenous turnover in Hanwang and Jushui area is not related to the CPE. [ABSTRACT FROM AUTHOR]

• Systematic zircon ages from offshore basins of eastern China are firstly reported. • Zircon age spectra of the modern Yangtze River firstly appeared in the late Miocene. • The Yangtze River with present erosion patterns was formed in the late Miocene. The Yangtze River originates in the Tibetan Plateau and supplies tremendous sediments to the East China Sea. To date, when and how the Yangtze River was formed is still highly debated. This paper presents systematic detrital zircon U-Pb ages (3575 grain ages from a total of 29 samples) from the Cenozoic sediments of offshore basins in East China. The zircon age spectra vary significantly in the South Yellow Sea Basin, but are relatively stable in the East China Sea Shelf Basin (ECB) and significantly different from those of present-day Yangtze River (PYR) before the late Miocene. Comparisons of zircon ages with potential source terranes suggest that the ECB has received detrital sediments that PYR features since the late Miocene, whereas before that time, the sediment provenances show a North China and Korea affinity. Considering the overwhelming sediment input from the eastern Tibetan Plateau, the first occurrence of the PYR-featured sediments in the ECB in the late Miocene suggests that the Yangtze River with approximately present erosion patterns was established at that time. This agrees well with the exhumation history of the eastern Tibetan Plateau. The unique zircon ages in the Eocene to mid-Miocene sediments imply that the Yangtze River with headwaters in eastern Tibet might not exist before the late Miocene. This study provides new insights into the Yangtze River evolution although more lines of evidence are required, which is mainly because of the complex river sediment source-to-sink processes and tectonic and climatic forcings in the large catchment. [ABSTRACT FROM AUTHOR]

The Bogeda Shan (Mountain) is in southern part of the Central Asian Orogenic Belt (CAOB) and well preserved Paleozoic stratigraphy, making it an ideal region to study the tectonic evolution of the CAOB. However, there is a long-standing debate on the tectonic setting and onset uplift of the Bogeda Shan. In this study, we report detrital zircon U-Pb geochronology and whole-rock geochemistry of the Permian sandstone samples, to decipher the provenance and tectonic evolution of the West Bogeda Shan. The Lower-Middle Permian sandstone is characterized by a dominant zircon peak age at 300–400 Ma, similar to the Carboniferous samples, suggesting their provenance inheritance and from North Tian Shan (NTS) and Yili-Central Tian Shan (YCTS). While the zircon record of the Upper Permian sandstone is characterized by two major age peaks at ca. 335 Ma and ca. 455 Ma, indicating the change of provenance after the Middle Permian and indicating the uplift of Bogeda Shan. The initial uplift of Bogeda Shan was also demonstrated by structural deformations and unconformity occurring at the end of Middle Permian. The bulk elemental geochemistry of sedimentary rocks in the West Bogeda Shan suggests the Lower-Middle Permian is mostly greywacke with mafic source dominance, and tectonic setting changed from the continental rift in the Early Permian to post rift in the Middle Permian. The Upper Permian mainly consists of litharenite and sublitharenite with mafic-intermediate provenances formed in continental island arcs. The combined evidences suggest the initial uplift of the Bogeda Shan occurred in the Late Permian, and three stages of mountain building include the continental rift, post-rift extensional depression, and continental arc from the Early, Middle, to Late Permian, respectively. [ABSTRACT FROM AUTHOR]

This study investigates heavy mineral assemblages in sediments of the modern Changjiang Delta (Yangtze River) and the Quaternary/Pliocene (Q/N) boundary strata within the delta area with the aim of deciphering changes in sediment provenance and the depositional environment during the Pliocene to Pleistocene transition. Major heavy mineral assemblages in the modern Changjiang sediments originate from their provenance rocks, while the distribution of unstable (amphibole), ultrastable (zircon, tourmaline, and rutile), and altered minerals (limonite, leucoxene) are closely related to the climate and the hydrodynamic environment within the catchment. The ratio of a certain unstable mineral (amphibole) to an altered mineral (limonite) is considered to be a sensitive indicator of the chemical weathering intensity that is largely affected by climate conditions. Heavy mineral data of core sediments reveal distinctly different environments and provenances between the upper (Quaternary) and lower (Pliocene) sedimentary strata in the Changjiang Delta. The Pliocene sediments are characterized by abnormally high contents of limonite (42%), leucoxene (8%) and zircon (15%), but an extremely low amphibole content (5%). Enrichment of zircon is indicated from the mid-lower Changjiang catchment, where granitoid rocks are widely distributed. The strong enrichment of altered minerals and the considerable great loss of unstable minerals suggest that Pliocene weathering was much stronger than it is nowadays. In contrast, high contents of amphibole, garnet, and pyroxene, and the low stable mineral content in the Quaternary strata indicate that sediment provenances may have extended to the upper Changjiang catchment, which underwent weak chemical weathering. These results imply that Changjiang as a large river system might have drained the East China's continental margin prior to the Q/N transition. The distinct heavy mineral assemblages found at the Q/N boundary in the Changjiang Delta are indicative of a drastic environment with provenance changes in response to intensive neotectonics. It is thus inferred that sensitive heavy mineral indices can be used to indicate the Q/N boundary in the Changjiang Delta, where reliable geochronological proxies have rarely reached an agreement. • We observe different heavy mineral assemblages in the modern Changjiang sediments. • Heavy mineral analysis was carried out on the core sediments from the Changjiang Delta. • Remarkable changes in heavy mineral assemblages were observed in Q/N boundary strata. • Sensitive heavy mineral indices may help recognize the Q/N boundary strata. [ABSTRACT FROM AUTHOR]