The Qiongzhou Strait is a key pathway for sediments and water exchange between the Beibu Gulf and the northern South China Sea, yet its provenance and associated sedimentary processes remain poorly constrained. In this study, AMS 14C dating, grain-size analysis, and detrital zircon U-Pb geochronology were applied to sediments of drilling core from the strait to track sediment provenance and its temporal evolution during the Holocene. The results show that detrital zircon ages from the sediments exhibit four prominent age populations at 105-146 Ma, 222-254 Ma, 416-435 Ma, and 784-952 Ma, indicating mixed sources from the Red River and Pearl River systems, and rivers on Hainan Island. Quantitative results reveal a dynamic shift in sediment supply in the Qiongzhou Strait: from a Pearl River-dominated source (81.3%) at 8.95 ka BP, to Red River-dominated source (88.6%) by 7.79 ka BP, and subsequently to increased input from Hainan Island (44.2%) during the late Holocene. These variations reflect the influence of Holocene climatic shifts and sea-level changes on sediment transport pathways of the strait. In addition, our results indicate that the Qiongzhou Strait was already open prior to 8.95 ka BP, enabling east-to-west sediment transport across the strait. The results provide new constraints on sedimentary processes in the Qiongzhou Strait and enhance understanding of source-to-sink systems in the northwestern South China Sea.

Depositional and erosional bedforms are prevalent in submarine environments worldwide, and have the potential to preserve critical records of continental margin evolution, ocean circulation, climate variability, and paleogeohazards. However, the origin and evolution of such bedforms remain debated. This study employs highresolution three-dimensional seismic reflection data to investigate the origin, evolution, and controlling factors of undulating bedforms on the eastern Shenhu slope, northern South China Sea. Morphometric analyses of these bedforms, as well as morphometric-based calculating of turbidity currents velocity, distinguish them as turbidity current-generated bedforms. Initiated since Marine Isotope Stage (MIS) 38 (horizon SB3) until the present, bedforms on the Shenhu slope are divided into two stages: (1) from MIS 38 to MIS 20 (horizons SB3-SB4), where erosional crescentic scours and elongated troughs, are formed under vigorous turbidity currents; (2) from MIS 12 to the present (horizon SB5-seafloor), where depositional bedforms, sediment waves, with near-linear crests, formed under relatively weaker current. Their evolution was governed by the interplay of the progradation of the paleo-Pearl River shelf-edge delta and the development of a horsetail normal fault system in the upper slope, with an increase in sediment supply since 1.6 Ma and a decrease in fault activity between 2.58 Ma until 474 ka (MIS 12). Fault-controlled conduits enhanced current velocity and erosion until MIS 20, which transitioned into unconfined flows and depositional waves as faults were progressively buried. These findings highlight the pivotal roles of sediment supply and seafloor topography in shaping deep-water sedimentary systems, offering insights into the sedimentary dynamics on continental margins.

The Beibu Gulf is a key region for investigating sediment transport and source-to-sink systems in the northern South China Sea, yet its sediment provenance remains poorly constrained. This study investigates core S08–2 from the eastern Beibu Gulf, integrating radiocarbon dating, clay mineralogy, and detrital zircon U-Pb geochronology to reveal sediment provenance and reconstruct sedimentary evolution since the Last Glacial Maximum. The results show that detrital zircon ages are dominated by three populations at 94–108 Ma, 241–247 Ma, and 418–439 Ma, indicating dominant contribution from the Red River and drainage systems of Hainan Island, with additional input from the Yunkai Massif. In contrast, clay minerals are dominated by smectite with minor kaolinite, illite, and chlorite, and show limited downcore variability, suggesting a stable fine-grained sediment source. This fine-grained fraction was mainly derived from reworked shelf sediments formed during the Last Glacial Maximum. During the Holocene, rising sea level and intensified ocean circulation enhanced fluvial sediment delivery, increasing the contribution from the Red River. These results reveal a pronounced grain-size dependence of provenance signals in the eastern Beibu Gulf, as coarse-grained detrital zircons record proximal inputs, whereas fine-grained clay minerals reflect regional sediment mixing.

The Cenozoic strata in the Rakhine Basin play a crucial role in hydrocarbon exploration; however, the provenance of these sedimentary rocks remains poorly investigated. In this study, we employed detrital zircon geochronology and geochemistry in the northern Rakhine shelf to investigate the provenance of sedimentary rocks and, combined with the previous studies, to identify their spatial and temporal variations and to elucidate the provenance evolution since the middle Miocene. The geochemical results of the zircons indicate that the primary source rocks of the sedimentary rocks are magmatic and metasedimentary rocks, particularly those of continental arc and post-collision granites. The origin of these rocks can be attributed to the Gangdese arc magmatic belt in the north, as well as the Indo-Burma Ranges in the east. The sedimentary rocks in the northern Rakhine yield zircon U-Pb age peaks primarily at 0-150 Ma, 400-600 Ma, 600-1000 Ma, and 1600-2100 Ma, with minor populations at 150-400 Ma and >2100 Ma. The detrital zircon provenance study shows that the zircons in the Miocene sedimentary rocks were primarily derived from the paleo-Brahmaputra River, with contributions ranging from 68.7% to 77.0%. During the Pliocene, the paleo-Brahmaputra River and the Chittagong-Tripura Fold Belt were the most significant sediment suppliers. Since the early Pleistocene, the northern Rakhine coastal region has played a significant role in their composition. The Brahmaputra River was the predominant contributor to upper Pleistocene rocks, and the Rakhine coastal region's contribution to the shelf intensified throughout the Pleistocene. In conjunction with regional tectonic evolution, our study underscores the importance of the Indian Plate subduction as a pivotal factor influencing the provenance transitions in the northeastern Bay of Bengal.

The ventilation of deep-water masses plays a critical role in carbon storage within the ocean, which in turn strongly influences atmospheric CO2 levels. The well-ventilated North Pacific Intermediate Water (NPIW), formed in the subarctic Pacific during glacial periods, was believed to have significantly influenced the water circulation in the northern Pacific. Yet, whether it could have extended southwards to the equatorial Pacific and modified the deep-water circulation of the South China Sea (SCS) remains debated. This study reconstructs the 43,000-year oxygenation history of the SCS Deep Water (SCSDW) by analyzing sediment core S12 from the Shenhu slope. We investigate the influence of glacial NPIW on SCSDW during the last glacial periods, using a combination of radiocarbon dating, grain size analysis, ichnology, and redox-sensitive trace element (RSTE). Cross-validation between RSTEs and trace fossil distributions reveals three distinct oxygenation phases in SCSDW: moderate oxygen conditions prior to the Last Glacial Maximum (LGM), anoxic conditions during the LGM and the last deglaciation, and oxic conditions during the Holocene. Turbidity current events introduced several periodic oxic episodes within the anoxic LGM and last deglaciation. The mean sortable silt sizes indicate a moderate intensity of SCSDW prior to the LGM, higher intensity during the LGM and the last deglacial, and lower intensity in the Holocene. The reconstructed oxygenation and current intensity of SCSDW presented in this study were compared with those of the NPIW and the Upper Circumpolar Deep Water (UCDW). Our findings do not support glacial NPIW influence on SCSDW oxygenation or intensity below 1700 m, challenging previous hypotheses of glacial NPIW intrusion into the deep SCS. Instead, changes in SCSDW oxygenation and intensity appear to be primarily controlled by its main source, the UCDW. However, the influence of NPIW on the upper boundary of SCSDW (above 1700 m) may have occurred during Heinrich event 1.

Riverine sediment transport is a crucial Earth surface process, with geochemistry offering insights into provenance, weathering, and controlling factors such as climate and tectonics. The Pearl River, a major sediment contributor to the South China Sea under a humid monsoon climate with diverse geology, presents an ideal drainage system for such study. This study presents the geochemical analysis and applies weathering indices and element ratios to sediments from the Pearl River tributaries, the main stream, and the estuary, systematically revealing the controls on composition variation within the Pearl River drainage. The results show that the major element compositions of the samples, such as SiO2, are slightly enriched compared to the upper continental crust (UCC). Al2O3 and Na2O are relatively depleted, and CaO exhibits the greatest variation in the drainage system. Rare earth elements (REEs) are significantly depleted in the Bei and Dong rivers, which are located in the Cathaysia Block. The Chemical Index of Alteration (CIA = 56.8 similar to 82.8) and Robust Weathering Index (RW = 23.3 similar to 60.2) indicate moderate weathering within the drainage basin, with an increasing trend from west to east. The discrimination function and Co/Th vs. La/Sc suggest a mafic source in the uppermost reach and a granite source in the Dong River. The sediment maturity is low (Index of Compositional Variability, ICV = 0.74 similar to 3.14), suggesting limited sediment recycling. Our study demonstrates that lithology and chemical weathering are two key factors governing the sediment compositional variations in the Pearl River system. This study delineates the spatial distribution of sediment geochemistry in the Pearl River and offers valuable insights into the drivers of compositional variability in the sediments of large drainage systems.

The South China Sea is the largest collection area of fluvial sediments among the semi-closed marginal seas, offering a desirable geological window for studying the source-to-sink transport process of terrigenous sediments in global marginal seas. K-feldspar is a common rock-forming mineral that is likely representative of the source terranes and could offer a more unbiased constraint on the sediment routing system. Moreover, its susceptibility to weathering prevents it from undergoing more than one sedimentary cycling, thereby providing a better indication of the material's primary source. In this study, Pb isotopes in detrital K-feldspars were analyzed on the northern shelf of the South China Sea with the aims of tracking the provenance of sediments and understanding the sedimentary process in the continental margin. The results show that the compositions of 206Pb/204Pb isotopes in detrital K-feldspars are mainly concentrated in the range of 18.5 to 19.0, with a wide range of 207Pb/204Pb ratios from 15.1 to 16.7. Quantitative provenance results indicate that the detrital K-feldspar primarily originated from the Pearl River catchment (55 %) and southeastern Chinese mainland (37 %), with minor contributions from Taiwan Island (8 %). For the Pearl River system, the Xi River is the most important sediment contributor, while the Bei River also provides a large amount of sediments. In contrast to detrital zircons, conspicuous differences in provenance were discerned for the two distinct proxies. This discrepancy arises from variations in the density and volume of K-feldspar and zircon grains, leading to their distinct sedimentary patterns during transportation. The study emphasizes the limitations of relying solely on a single proxy and highlights the utility of Pb isotopes in detrital K-feldspar for understanding the sedimentary processes within the marginal source-to-sink systems.

As the widespread and prominent features of the ocean, seamounts are served as natural repositories for sediments, creating a special environment for understanding the sediments from terrigenous source to oceanic sink. However, opportunities to delve into the provenance and sedimentary processes of seamounts has been notably restricted. Here we examine the geochemistry and clay minerals of sediments from the Zhongnan Seamount in the South China Sea, with aims to reveal the provenance of sediments and investigate the transport pathways during the glacial-interglacial periods. Geochemical results indicate that the parent rocks of the sediments vary from andesite and felsic volcanic rocks, which were formed under tectonic settings similar to the continental island arc, suggesting a predominantly terrigenous source. Provenance results indicate that the sediments of the seamount were primarily derived from the islands of Taiwan Island, Luzon, and the Red River, with the sources of sediments varied during glacial-interglacial periods. Since MIS 3, shifts in the provenance of seamount sediments have been associated with variations in sea level prompted by climate change and the transport dynamics of ocean currents. This study proposes the potential of sediments in seamounts to record the hydrodynamic patterns and reveal transport pathways in the source-to-sink systems.

Glacial-interglacial sea-level fluctuations affect meridional overturning dynamics in the marginal South China Sea, although their influence on intermediate water exchange with the North Pacific remains unclear. Here, we reconstruct the evolution of South China Sea Intermediate Water since about 31,000 years ago using radiocarbon dating, grain size, redox-sensitive trace elements, and ichnological data from core S17 at 751 m depth. The results reveal more intense flows, better ventilation, and higher oxygenation during the glacial interval. These conditions stemmed from the closure of shallow seaways (Taiwan and Karimata, <50 m sills; Balabac, ~100 m sill) during lowered sea level, which impeded outflow and enhanced downwelling of the South China Sea Surface Water. Comparisons with North Pacific Intermediate Water proxies indicate warmer, saltier South China Sea Intermediate Water outflows modified mixed-North Pacific Intermediate Water during Heinrich Event 1 and the Younger Dryas, potentially weakening deep stratification and facilitating carbon dioxide outgassing. Closures of shallow straits impede South China Sea surface water outflows and amplify intermediate water ventilation via downwelling and mixing with deep water, according to combined analysis of radiocarbon dating, grain size, trace elements, and ichnological data.

The Ulgen porphyry Mo deposit, recently discovered in the northeastern segment of the Derbugan metallogenic belt, NE China, is a large and hidden ore deposit. Investigation of this deposit provides insights into the geodynamic background and metallogenic mechanism of Mesozoic porphyry Mo deposits that are exposed elsewhere in NE China. The host rocks consist of muscovite monzonitic granite (MMG) and biotite granitic porphyry (BGP), which are intruded into Lower and/or Middle Jurassic intermediate-felsic volcanic-sedimentary rocks and pre-ore monzogranitic porphyry (MP). Zircon laser ablation−inductively coupled plasma−mass spectrometric (LA-ICP-MS) U-Pb age dating indicates that the MMG and BGP were emplaced at 144.9 Ma and 144.7 Ma, ca. 14 m.y. younger than the intrusion age of MP (159.3 Ma). Molybdenite Re-Os isotopic dating indicates that Mo mineralization occurred at 144.9 Ma, almost simultaneously with the 145 Ma magmatic activity. Geochemically, all of the Ulgen granitoids are enriched in large ion lithophile elements (e.g., Rb, Th, U, and K) and light rare earth elements, and are depleted in high field strength elements (e.g., Nb, Ta, and Ti). The pre-ore MPs belong to I-type granites with moderately negative Eu anomalies (Eu/Eu* = 0.62−0.65), whereas the syn-ore MMGs exhibit S-type affinity with pronounced negative Eu anomalies (Eu/Eu* = 0.29−0.39). The ore-forming BGPs display adakite-like geochemical features in terms of high-Sr, low-Y, and low-Yb contents, and slightly negative Eu anomalies (Eu/Eu* = 0.72−0.74). All intrusive rocks have relatively low initial (87Sr/86Sr)i ratios (0.7044−0.7055) and positive εNd(t) values (+1.15 to +2.65), positive εHf(t) values (+4.0 to +9.4), young two-stage Nd and Hf model ages (tDM2(Nd) = 841−731 Ma, tDM2(Hf) = 943−604 Ma), and moderate (206Pb/204Pb)i (18.300−18.402), (207Pb/204Pb)i (15.557−15.564), and (208Pb/204Pb)i (38.180−38.307) ratios. Therefore, it is most likely that these intrusive rocks originated from a mixture of two sources of magma derived from the mantle and juvenile lower crust, in which there were variable degrees of the fractional crystallization of ilmenite, apatite, and plagioclase. Rather than the partial melting of oceanic slabs, the fractional crystallization of hornblende and accessory minerals (e.g., ilmenite and apatite) induces the adakitic geochemical signature of BGPs. Compared with the BGPs, the MPs had a relatively deeper magma source region, whereas the MMGs had a relatively shallower magma source region. The BGPs and the Mo-bearing fluids of the Ulgen deposit were most probably derived simultaneously from magma that was generated at an extensional setting following the closure of the Mongol-Okhotsk Ocean during the latest Jurassic. Enrichment of Mo by late-stage fractional crystallization most likely played an important role in concentrating Mo during the formation of the Ulgen hidden Mo deposit.

The northwestern continental margin of the South China Sea, extending from the broad shelf and canyon-growth slope across the Xisha Trough, represents a relic crustal rift that eventually connects to the abyssal plain. However, the provenance and source-to-sink process of sediments in this special topography remains unclear. In this study, we present the detrital zircon U-Pb geochronology of surface sediments from the northwestern margin of the South China Sea to identify the sediment provenance, track the transport pathway, and understand the source-to-sink process in this margin. The results showed that detrital zircons exhibit a wide range of U-Pb ages from 3,062.9 to 41.5 Ma and are characterized by peaks centered on 140–154 Ma, 240–258 Ma, 425–452 Ma, and 738–991 Ma. Statistical analysis indicated that the clastic sediments on the shelf closely resemble those sourced from the Pearl River system. Conversely, sediments on the slope and abyssal plain demonstrated characteristics indicative of multiple sources, primarily originating from the Pearl River, with a minor contribution from the Red River. Further quantitative study revealed a progressive increase (from 8.2% to 43.2%) in the prevalence of Red River-derived sediments with ascending water depth on the shelf and slope, whereas sediment influx in the deepest sector remains predominantly sourced from the Pearl River. This study emphasizes the controls of topography and currents in modulating the transportation of coarse-grained and fine-grained sediments within the source-to-sink system and provides a favorable solution for reconstructing the sedimentary process in continental margins.

U–Pb geochronology of detrital zircon is a powerful proxy that has seen significant growth and led to breakthroughs in understanding the sedimentary process and tectonic evolution in the South China Sea and its adjacent source terranes. However, uncertainties remain in determining the provenance of sediments due to the lack of systematic age compositions of the surrounding eroding sources. Here we present a new zircon U–Pb geochronological dataset from major drainage systems in seven geological domains surrounding the South China Sea, including large and coastal rivers in the South China and Indochina blocks, as well as rivers on the islands of Hainan, Taiwan, Luzon, Palawan, and Borneo. This dataset, combined with published data, forms a comprehensive detrital zircon U–Pb geochronological and Hf isotopic database (n = 21,580) for fluvial systems discharging into the South China Sea. The results show that these detrital zircons, with ages ranging from the Archean to the Cenozoic, have two major age groups at 260–220 Ma and 130–80 Ma and subordinate age populations at 2600–2400 Ma, 1900–1700 Ma, 1000–600 Ma, 500–390 Ma, and 40–20 Ma, corresponding to the major tectono-magmatic events in East and Southeast Asia. Detailed comparisons reveal distinct age signatures for each drainage system correlated with the basement characteristics of river basins, indicating a heterogeneous zircon age distribution. The findings indicate that the surrounding terranes have a significantly different crustal evolution history, with juvenile crustal growth occurring in the East and Southeast Asian continent predominantly during 2600–2400 Ma, 1800–1500 Ma, and 1000–700 Ma, and on the island of Luzon during the Cenozoic. This study provides a detrital zircon record for drainage systems surrounding the South China Sea and presents a method for defining regional first-order strategies to characterize the provenance and crustal evolution of the source terranes. The integrated dataset provides a critical foundation for investigating regional sediment provenance and tectonic correlations in East and Southeast Asia.

The Cenozoic sedimentary rocks on the island of Taiwan hold significant implications for understanding tectonic and drainage evolutions in SE China, but the provenance of these rocks remains controversial. Here we derived Pb isotopes in detrital K-feldspars from the drainage systems in western Taiwan to evaluate the provenance of sediments and reveal the evolution of Cenozoic sedimentary. Our findings indicate that the fluvial sediments eroded from the Cenozoic sedimentary rocks were primarily derived from the eastern Cathaysia Block (91%), with minor contributions from the Yangtze River catchment. Spatially, the northern part of Taiwan contains more sediments derived from the Yangtze River catchment than the southern part. The Cathaysia Block has been crucial in supplying detritus to Taiwan since the Eocene, whereas the contribution of the Yangtze Block varies greatly at different sedimentary periods. Two major shifts in provenance occur at the boundaries between Eocene, Oligocene, and Miocene, which may be related to the changes in drainage systems and landscapes in eastern China.

Active and passive continental margins exhibit significant differences in sediment transport. However, opportunities to quantify these specific sedimentary processes remain limited. The northeastern South China Sea hosts both active and passive continental margins, offering a distinct opportunity to compare the relative contributions from a large passive continental margin with those from a smaller but more dynamic active margin. We present detrital zircon U-Pb ages from marine sediments in the northeastern South China Sea to decipher their provenance and reveal the control of transport processes in the margins. Our results show varied provenance of sediments from the shelf to the trench. In the continental shelf, sediments were primarily derived from the Jiulong and Gaoping rivers, controlled by the topography and ocean currents in the passive margin. In contrast, the sediments in the submarine canyons predominantly originated from the Gaoping and Zhuoshui rivers in western Taiwan Island. Quantitative results indicate that the Gaoping submarine canyon provided approximately 86.2% of sediments to the Manila Trench by directly linking to the Gaoping River in the active margin. Based on the provenance results, we propose a distinct sedimentary process in the active and passive margins. In passive margins, sediments from drainage systems enter the shelf and are transported by ocean currents, but topographic highs often block these sediments, preventing them from reaching the deep sea. In contrast, active margins feature narrow shelves, which facilitate direct connections between submarine canyons and river mouths, allowing gravity flows to carry sediments directly to the trenches. Our study provides an understanding of the sediments transported from rivers to trenches in the northeastern South China Sea and highlights the controls (ocean currents, dramatic topography, and gravity flows) during the sediment transport in the continental margins.

Ichnological analysis plays a pivotal role in the study of sedimentary basins as it records the evolution of paleoenvironments and the associated changes, providing crucial support for sedimentological and stratigraphic interpretations. Yet, rare ichnological studies on deep-marine hyperpycnites have been conducted, resulting in less conclusive ichnological characterization of deep-marine hyperpycnites, compared to pelagites/hemipelagites, turbidites, and contourites. This study conducted detailed investigation of trace fossils distribution within deep-marine hyperpycnites, using non-destructive X-ray computed tomography scanning. The sediment core S19 on the upper Shenhu slope in the northern South China Sea documented deep-marine hyperpycnites facies S3, S2L, and L, possibly representing the proximal to distal hyperpycnal lobe. In this study, hydrodynamic energy and salinity are suggested to be the dominant stress factors within proximal lobes, resulting in less bioturbation and scattered distribution of vertical trace fossils such as Skolithos and Siphonichnus. In the middle lobe, the environment is predominantly characterized by moderate to high hydrodynamic energy, a rich abundance of organic material, and occasional slight salinity fluctuations. These environmental factors have led to the prevalence of trace fossils such as Arenicolites, Conichnus, Nereites, Phycosiphon, Rosselia, Scolicia, and Thalassinoides, which are well-represented in this region of the lobe. The organic material concentrated within the distal lobe to fringe acts as the main stress factor promoting opportunistic organism colonization and the formation of deposit-feeding traces. Therefore, the represented traces within distal hyperpycnites are mainly Nereites and Phycosiphon. This study provides a detailed investigation into trace fossil distribution within deep-marine hyperpycnal lobes, enriching our knowledge of the ichnology of deep-marine hyperpycnites.

The Holocene sedimentary evolution in the northern South China Sea has significant implications for sedimentary records resulting from combinations of climate change, sea level rise, and changes in surface circulation. U-Pb geochronology and Lu-Hf isotopes of detrital zircons from the Holocene sediments at the head of the Shenhu submarine canyons, integrated with onshore geochronological data reveal variations in provenance related to these factors. The detrital zircons exhibit a wide range of U-Pb ages from 3829.7 to 41.5 Ma characterized by peak ages centered on 140-154 Ma, 240-258 Ma, 425-452 Ma and 738-991 Ma. Zircon Hf isotopic compositions show a broad range of 176Hf/177Hf ratios from 0.2800714 to 0.282924, with & epsilon;Hf(t) values ranging from -27.8 to +14.3. Our results suggest that the Holocene sediments were primarily derived from the Pearl River system and the drainage systems in Taiwan, and the sources in Hainan and Luzon are not represented in these sediments. A rapid shift from Pearl River-dominated to Taiwan-dominated provenance occurred between 4.91 and 4.45 ka BP, which is interpreted to be caused by sea level rise and variations in the surface circulation in the northern South China Sea during the Holocene. Our study also reveals that the reworking of ancient continental crust dominated the evolution of the South China Craton, including tectonic-magmatic events at ca. 2491 Ma, 1843 Ma, 968 Ma, 810 Ma, 440 Ma, 251 Ma and 147 Ma. In contrast, Neoproterozoic accretion of the Cathaysia and Yangtze blocks was accompanied by juvenile additions to crustal growth.

The northern shelf of South China Sea is an important passageway for the transportation of sediments from the terrigenous source to the oceanic sink, but the provenance and dispersal patterns of sediments remain largely unclear. Here we report the results of zircon grain-size analysis and U-Pb geochronology to investigate the sediment provenance and illustrate the transport and dispersal patterns of sediments on the continental shelf of the northern South China Sea. The results show that detrital zircon U-Pb ages within sediments are characterized by a major peak at ca. 150 Ma, as well as three minor age populations at ca. 240 Ma, 400-500 Ma, and 900-1000 Ma. A detailed provenance study suggests that these sediments were primarily derived from both the Pearl River catchment and the drainage systems in Taiwan Island. Our study confirms that the transportation and dispersion of sediments were largely controlled by both topography and hydrodynamics of sea. The sediments in the inner continental shelf were transported from the Pearl River drainage system and subject to the Guangdong Coastal Current, whereas the sediments in the middle and outer continental shelf were markedly influenced by the South China Sea warm current. This study elucidates the transport and dispersal patterns of detrital sediments in the marginal sea by comprehensive analyses of detrital zircon grains.

The granites of ambiguous geodynamic mechanism in the Qin-Fang tectonic belt (SW China) were studied in detail based on petrological, element geochemical, zircon U-Pb geochronological, and Hf isotopic data. LA-ICPMS U-Pb analyses on zircon yield ages of 248–245 Ma for the granites from the Qin-Fang tectonic belt. The geochemical data show that they are high-K, calc-alkaline, and peraluminous series. Their ε Hf ( t ) values are from −14.01 to −7.75 with two-stage model ages of 1.74–1.43 Ga. These data, integrated with low Al 2 O 3 /TiO 2 , Rb/Sr, Rb/Ba, and (Na 2 O + K 2 O)/(FeO T + MgO + TiO 2 ) ratios, and high CaO/Na 2 O ratios for the granite, suggest an origin from psammite source which was contaminated by mantle-derived components. These observations, in combination with the age data and stratigraphic records in the Jinshajiang, Ailaoshan, and Hainan Island areas suggest that the granites were formed in a post-collision tectonic setting. The Qin-Fang tectonic belt was likely a branched ocean basin of the eastern Paleo-Tethys.

Hyperpycnites record information on sedimentary processes and climate change and play a significant role in hydrocarbon exploration. However, deep-water hyperpycnites can hardly be differentiated from intrabasinal turbidites since their control factors are not well understood. More detailed studies are needed to improve the knowledge of hyperpycnites. This study aims to identify and characterize hyperpycnites in the Shenhu slope and investigate their evolution in response to sea-level and climate changes using sediment gravity cores, combined with detailed grain size analysis, X-ray fluorescence scanning, X-ray computed tomography scanning, radiocarbon dating, and microscopic observations. Hyperpycnites and internal wave redistributed deposits were identified in core S19 since 42 cal ka BP. Internal wave redistributed deposits served as background deposit and dominated in the middle-late Holocene, while hyperpycnites dominated the Marine Isotope Stage 3 sequence form the early Holo-cene. The hyperpycnites facies S3 interbedded with S2L occurred during Marine Isotope Stage 3, facies L appeared in Last Glacial Maximum (LGM) strata, while facies S2L dominated the strata after LGM to the early Holocene. The facies distribution suggested that the strength and distribution of hyperpycnal flow were higher in warm and humid stages with low sea-level. Lower flood flows discharge in cold and dry stages limited the generation and extensional distance of hyperpycnal flows, although the sea-level was low in this stage. However, high sea-level combined with longshore and Surface waters in warm and humid stages, prevented the travel of hyperpycnal flows into deep basin. The study of hyperpycnites in the Shenhu slope reveals that the formation of deep-water hyperpycnites is influenced by a combination of factors, including sea-level fluctuations, climate change, and oceanographic processes. The amount of precipitation in the drainage basin determines the intensity and generation of hyperpycnal flows, while sea-level fluctuations affect their travel distance to the deep-water setting. Additionally, oceanographic processes such as longshore current can significantly alter hyperpycnal flows near the river mouth and shelf area, preventing them from reaching the deep basin. & COPY; 2023 Published by Elsevier Ltd.

The sulfur isotopic composition of marine pyrite (δ34Spyr) is one of the major geochemical tools to reconstruct global changes in Earth's surface environment. Storm-driven variations in depositional environments, however, can play key roles in modifying the δ34Spyr signal. Here we present δ34Spyr values in a complete Holocene muddy storm deposit on the East China coastal plain, which is identified by comprehensive analyses of sediment components, organic matter composition, bulk organic carbon isotopic ratios, carbon and oxygen isotopic ratios of carbonates and trace element concentrations. We find that positive (+5.8‰ to +15.8‰) and negative (−9.0‰ to −19.7‰) δ34Spyr values were preserved in two successive intervals of the muddy storm deposit (ca. 62 cm long), corresponding to the high-energy storm peak phase (HESPP) and the waning-energy late storm phase (WELSP), respectively. We propose that the 34S enrichment in pyrite from the HESPP is most likely due to a combination of storm reworking of sediments and high sedimentation rates, which involves various physical and chemical processes leading to the accumulation of 34S-enriched pyrite, such as oxidation of near-surface sulfides, reduced exchange of sulfate between sediment pore fluids and the overlying water column, and/or input of excess reactive iron minerals. In contrast, lower sedimentation rates and limited sedimentary remobilization during the WELSP allow the isotopic signal of early-formed 32S-enriched pyrite to be preserved. The striking shift in δ34Spyr values, therefore, reflects a dramatic change in the local depositional environment between the HESPP and WELSP, suggesting that non-steady-state deposition induced by storm activity facilitates the formation of isotopically “heavy” pyrite. This sharp shift can be further generalized as a characteristic feature of δ34Spyr values in storm deposits. Our work highlights the critical impact of weather- and climate-event-driven depositional variations on δ34Spyr values, adding to the growing evidence emphasizing the local environmental and diagenetic controls on these records.