Yellow Sea Basin Research Articles

The transition from Palaeo-Asian to marginal Pacific tectonic domain experienced in the Eastern North China Craton: evidence from Late Jurassic sediment provenance in the North Yellow Sea Basin

The transition from Palaeo-Asian to marginal Pacific tectonic domain experienced in the Eastern North China Craton: evidence from Late Jurassic sediment provenance in the North Yellow Sea Basin

Co-construction of molecular-level uranyl-specific “nano-holes” with amidoxime and amino groups on natural bamboo strips for specifically capturing uranium from seawater

Efficiently capturing of uranium (VI) [U(VI)] from seawater elicits unparalleled attraction for sustaining the uplifted requirement for nuclear fuel. However, obtaining the abundant U(VI) resource from seawater has always seriously restricted by competitive adsorption from higher concentrations of competitors, especially vanadium (V) [V(V)]. Herein, based on amidoximized natural bamboo strips with hierarchical porous structure, the molecular-level uranyl-specific “nano-holes” was co-constructed by the intramolecular hydrogen bonds for specifically trapping U(VI) from seawater. Manipulating the branched degrees of amino groups enabled the creation of a series of the molecular-level uranyl-specific “nano-holes” that exhibit ultrahigh affinity and selective adsorption of U(VI) with a adsorption capacity 1.8 fold higher compared to that of V(V) after 30 days floating in the Yellow Sea basin, conquering the long-term challenge of the competitive adsorption of V(V) for amidoxime-based adsorbents applied to extract U(VI) from seawater. The diameter of the molecular-level uranyl-specific “nano-holes” is approximately 12.07 Å, significantly larger than (UO2)3(OH)3+ (10.37 Å) and smaller than HV10O285-, thereby exhibiting specifically trapping of U(VI) in a series of adsorption experiments with different U(VI)-V(V) ratios. Besides, the adsorption model based on the combination of experimental and theoretical results is accompanied by "hydrogen bond breaking and coordination bond formation".

Structural Characteristics and Tectonic Evolution of the Wunansha Uplift in the South Yellow Sea Basin, China

By selecting typical seismic sections to carry out detailed structural interpretation, the structural style features of the Wunansha Uplift in the South Yellow Sea basin were systematically combined, and the compressional structures (imbricate, opposite/back thrust, and Y-shaped structures), strike-slip faults (positive flower-shaped faults), and extensional normal faults (listric-shaped normal faults) were identified. On this basis, combined with the characteristics of the regional stress field and the background of deep geodynamics, the genetic mechanism and structural evolution of the structural style in the Wunansha Uplift were defined. The stress mechanism of the compressional structures originated from the initial high-speed and low-angle NW subduction of the paleo-Pacific plate during the early Yanshanian movement in the Early Jurassic. The regional strike-slip fault was mainly a positive flower structure with compression and torsion characteristics, and its stress mechanism originated from sinistral shear caused by the Early Cretaceous low-angle NNW subduction of the paleo-Pacific plate. The Tan-Lu fault in eastern China also had sinistral shear characteristics in this period. The extensional normal fault was characterized by a listric shape, which developed along the northern boundary of the Wunansha Uplift, that is, the connection between the Wunansha Uplift and the Southern Depression of the South Yellow Sea basin. The stress mechanism was derived from the transition of the paleo-Pacific plate from low-angle to high-angle subduction during the late Yanshanian movement in the Late Cretaceous. Simultaneously, the tectonic stress system in eastern China also changed from compressional to tensional.

Characteristics and Research Direction of Triassic in the South Yellow Sea Basin, China

To advance oil and gas exploration in the South Yellow Sea Basin, characteristics of Triassic, including its correlation with regional strata, distribution, lithology characteristics, and karst development characteristics, are studied by geological mapping. Results show that there exist Zhouchongcun Formation and Qinglong Formation in the Triassic. Zhouchongcun Formation corresponds to Dongma Formation in the lower Yangtze Region, Badong Formation in the middle Yangtze Region, and Lekoupo Formation in the upper Yangtze region. The upper Qinglong Formation corresponds to the Nanlinghu Formation and Longshan Formation in Xiyanzi district, and Jialingjiang Formation in the middle and upper Yangtze region. Its lithology is limestone, intercalated with marl, mudstone, and argillaceous siltstone. The lower Qinglong Formation corresponds to the Yinkeng Formation at the lower Yangtze group. The lower Qinglong group has the complex lithologic characteristics, which can be divided into six categories from top to bottom, including limestone weathering crust layer, limestone, marl with mudstone, mudstone with limestone, marl with limestone, and mudstone interbedding limestone and mudstone. Karst phenomenon is well developed in the lower Qinglong Formation, and the thickness of weathering crust, revealed by cz35-2-1 well, reaches 60.5 m. Triassic in the South Yellow Sea Basin is mainly distributed in the central uplift and southern depression, showing the regional differences in distribution. Karstification is probably the main reason for this significant difference. Identification of karst phenomenon and stratigraphic division method towards Triassic drilling coring are two important directions of Triassic study in the South Yellow Sea Basin.

Characteristics and influencing factors of Cretaceous reservoir in eastern depression of North Yellow Sea basin

Cretaceous is the key exploration target layer in the eastern depression of North Yellow Sea basin, which has a good prospect for oil and gas exploration. Its huge oil and gas resource potential has attracted great attention from petroleum geologists. In this study, the main rock types, reservoir space types, petrophysical characteristics and main controlling factors of Cretaceous reservoir are studied through core observation, thin section identification, petrophysical analysis and scanning electron microscope observation. The results indicate that the main rock types of Cretaceous reservoir in the eastern depression of North Yellow Sea basin are lithic arkose, feldspar lithic sandstone, some feldspar sandstone and a small amount of lithic sandstone. The average porosity is 6.9%, and the average permeability is 0.46 × 10−3 μm, so Cretaceous reservoir in the study area has poor petrophysical characteristics and belongs to low porosity and low permeability reservoir. Cretaceous reservoirs in the study area mainly develop in secondary pores, which are dominated by dissolution pores (including intragranular pores, intercrystalline pores and cleavage pores), followed by fractures. The main factors affecting petrophysical characteristics of Cretaceous reservoir in the study area are provenance properties, sedimentation, diagenesis (including compaction, cementation and dissolution) and tectonism. The provenance properties and sedimentation are the prerequisite conditions affecting petrophysical characteristics. Petrophysical characteristics of feldspar sandstone of Cretaceous reservoir in the study area and lithic arkose are better than that of feldspar lithic sandstone. Both compaction and cementation reduce the porosity and permeability of Cretaceous reservoir in the study area and make petrophysical characteristics become poor, whereas the dissolution and tectonism play an important role in improving petrophysical characteristics of Cretaceous reservoir.

Sedimentary Control on the Carboniferous-Early Permian Heterogeneous Porous Carbonate Reservoirs Distribution in the Central Uplift of the South Yellow Sea Basin

Sedimentary Control on the Carboniferous-Early Permian Heterogeneous Porous Carbonate Reservoirs Distribution in the Central Uplift of the South Yellow Sea Basin

Geochemical characteristics and organic matter enrichment mechanism of Permian black mudstone in the South Yellow Sea Basin, China

The middle Permian organic matter-rich mudstone in the South Yellow Sea Basin has been considered the most important source rock for Paleozoic reservoirs in the basin. However, information on the variation in depositional environment within the Qixia Formation to lower Longtan Formation interval is lacking, and the formation mechanism of these organic matter-rich mudstones is unclear. Based on a series of geochemical analyses of borehole CSDP-2, the paleoclimatic conditions, nature of the watermass, paleoproductivity and terrestrial detrital influx of the different intervals in the middle Permian of the South Yellow Sea Basin were assessed to determine the main factors controlling organic matter enrichment. All three intervals (from the Qixia Formation to the lower Longtan Formation) were deposited under a relatively warm and humid paleoclimate with moderate terrestrial detrital input. The Qixia Formation was deposited under oxic paleoredox conditions in a normal marine environment. During deposition of the Gufeng Formation, the paleoredox conditions changed to suboxic with intermittent anoxia associated with paleoproductivity higher than that in the other studied intervals. The lower Longtan Formation was characterized by a brackish watermass, suboxic paleoredox conditions and low paleoproductivity. The covariant relationships among paleoproductivity, paleoredox conditions, watermass salinity indicators and TOC content indicate that paleoproductivity was the critical factor controlling organic matter abundance. High primary productivity not only provided organic matter but also enhanced organic matter preservation by consuming oxygen in the watermass, which resulted in the formation of the organic matter-rich source rock in the Gufeng Formation. • The Gufeng Formation exhibits higher paleoproductivity than other two intervals. • Higher paleoproductivity resulted in relative reducing redox condition. • Paleoproductivity level controls the deposition of OM-rich source rock.

Hydrocarbon Generation Kinetics of Salinized Lacustrine Source Rocks in the Upper Cretaceous-Paleocene South Yellow Sea Basin, Offshore Eastern China

Hydrocarbon Generation Kinetics of Salinized Lacustrine Source Rocks in the Upper Cretaceous-Paleocene South Yellow Sea Basin, Offshore Eastern China

Response of provenance transition of Middle Jurassic–Early Cretaceous sediments to tectonic domain transformation in the North Yellow Sea Basin, Eastern North China Craton

In the Late Mesozoic, the Eastern North China Craton changed from being controlled by the Palaeo‐Asian tectonic domain to the marginal Pacific tectonic domain. The Eastern North China Craton transformed the E–W compression to NNE–SSW extensional tectonics under the influence of two tectonic domain transformations. However, the timing of the transformation of the tectonic domains remains controversial. The North Yellow Sea Basin is located in an important position in the Eastern North China Craton at the junction of the Pacific and Eurasian plates and is controlled by two tectonic domains. Therefore, the sediments in the basin are faithful records of the transformation of the two tectonic domains. Based on the latest and high‐precision detrital zircon U–Pb dating data, sandstone modal analysis, and elemental geochemical analysis in the North Yellow Sea Basin combined with regional tectonic, palaeontological, and palaeoclimatic evidence, this paper discusses the provenance from the Middle Jurassic to Early Cretaceous, which responds to the Late Mesozoic tectonic domain transformation in the Eastern North China Craton, and provides important evidence of provenance in the North Yellow Sea Basin to determine the time of tectonic domain transformation. These results suggest that the source rocks of sediments in the North Yellow Sea Basin have changed from ancient sediments (ancient craton/recycle orogenic belt) in the Middle Jurassic to Late Jurassic, to felsic igneous rocks in the Early Cretaceous. The peak of zircon U–Pb ages changed from 234, 1,842, and 2,429 Ma in the Late Jurassic to 217 and 1,871 Ma in the Early Cretaceous. The provenance changed from the Sulu Orogenic Belt and Precambrian basement of the Jiaodong Peninsula in the Late Jurassic, to the igneous rocks and Precambrian basement of the Liaodong Peninsula and Korean Peninsula in the Early Cretaceous. The provenance direction of the sediments changed from south‐west in the Late Jurassic to the north and south‐east in the Early Cretaceous. The tectonic setting of the basin changed from compression to extension. The changes in the peaks of zircon U–Pb age, characteristics of the source rocks, provenance direction, and basin tectonic setting in the Middle Jurassic to Early Cretaceous in the North Yellow Sea Basin are a response to the change from E–W compression to NNE–SSW extensional tectonics caused by the transformation of two tectonic domains. In the Early Cretaceous, the Eastern North China Craton completed the transformation of two tectonic domains that were influenced and controlled by the marginal Pacific tectonic domain.

Simple one-step synthesis of woven amidoximated natural material bamboo strips for uranium extraction from seawater

The uranium(VI) (U(VI)) extraction from seawater was crucial for future energy problems such as increasingly depleted fossil fuels and serious environmental pollution, and it could improve the current situation of limited U(VI) reserves on land. In this study, the natural material bamboo strips (BS) were utilized due to the flexibility and richness of various functional groups, and the amidoximized bamboo strips (AOBS) could be directly prepared by a simple one-step method. The amidoximation of materials not only adjusted the optimal adsorption pH from 4 to 6, but also advanced the hydrophilicity, speeded up the reaction rate (adsorption equilibrium within 1 h, about 0.17 times of BS), and increased the adsorption capacity (qe = 268.41 mg g−1 at pH = 6, about 1.7 times of BS). Importantly, the AOBS maintained its initial stitchability through flexibility adjustment, and was woven into a macro-shaped adsorbent (AOBS-M). After being placed in the Yellow Sea basin for 30 days, approximately 44.75 g of crude U(VI) (U(VI) content = 40.45 mg) was obtained (qe = 0.97 mg g−1), and it showed the excellent selectivity for U(VI). The AOBS-M not only overcame the problem that the existing adsorption materials were difficult to achieve macroscopic large-area molding, but also realized the flexibility adjustment during the modification process by controlling the reaction conditions, and promoted the industrial development of U(VI) extraction from seawater.

Sedimentology, geochronology, and provenance of the late Cenozoic “Yangtze Gravel”: Implications for Lower Yangtze River reorganization and tectonic evolution in southeast China

AbstractThe evolution of the Yangtze River, the longest river in Asia, provides a spectacular example for understanding the Cenozoic interaction between tectonics, climate, and surficial processes. The oldest Lower Yangtze deposits, characterized by ~100-m-thick sequences of unconsolidated conglomerate, sandstone, and siltstone, referred to as “Yangtze Gravel,” have been recently dated >23 Ma, indicating a pre-Miocene establishment of a through-going river. However, the link between river integration and tectonic evolution has never been established due to the limited study of these sediments.Here, we report sedimentology, geochronology, and provenance of the Yangtze Gravel based on 17 stratigraphic sections exposed along the Lower Yangtze River. Our new chronostratigraphic results, including 40Ar/39Ar ages from the overlying basalt and fossil-based stratigraphic correlation, suggest an early-middle Miocene age for these sediments. Detailed analysis of lithofacies reveals several sequences of coarse-grained channel-belt deposits (channel fills and bars), indicating braided alluvial deposition across the Jianghan Basin, North Jiangsu-South Yellow Sea Basin, and East China Sea Shelf Basin. This ancient Lower Yangtze River is further characterized by petrography and detrital zircon U-Pb geochronology results which show similar provenance and erosion pattern as the present-day Yangtze River. However, the ancient river in early-middle Miocene is an alluvial, bedload-dominated braided river with higher stream power and a more prolonged course flowing into the East China Sea Shelf Basin. These differences between ancient and modern Lower Yangtze River reflect varied climate and paleogeography in southeast China during the late Cenozoic.Compared with the Paleogene red-colored, halite-bearing, Ephedripite pollen-dominated, lacustrine deposits in Jianghan Basin and North Jiangsu-South Yellow Sea Basin, the deposition of yellow to green-colored, coarse-grained, arboreal pollen, and wood-dominated Yangtze Gravel indicates a drainage reorganization from hydrologically closed lakes to a through-going river system during late Oligocene to early Miocene. During Paleogene, rift basins were filled by alluvial and fluvial-lacustrine deposition with restricted flow distance and local sources. From late Oligocene to early-middle Miocene, the post-rift subsidence opens a path for the ancient Lower Yangtze River connecting the Jianghan Basin, North Jiangsu-South Yellow Sea Basin, and East China Sea Shelf Basin. We attribute the drainage reorganization of the Lower Yangtze River to be a surficial response to Cenozoic tectonics, particularly the western Pacific subduction, in southeast China. The deposition of the widespread, coarse-grained Yangtze Gravel is probably due to the combined effects of catchment expansion and strong monsoonal climate in East Asia.

Characteristics and classification of paleozoic tight reservoirs in the central uplift of the South Yellow Sea Basin

Several sets of Paleozoic tight reservoirs are developed in the Central Uplift of the South Yellow Sea Basin. A qualitative analysis of the microscopic pore structure of the tight reservoir rocks was carried out through cast thin slice and scanning electron microscopic image observation. Based on reservoir petrophysical properties, thirty core samples in the Central Uplift of the South Yellow Sea Basin were selected for high-pressure mercury intrusion (HPMI) analysis, which was then combined with fractal calculation to classify and evaluate the tight reservoirs. The analysis of the HPMI curves and related parameters shows that the Paleozoic tight reservoirs can be divided into three types: Type-A, Type-B and Type-C. Type-A sandstone reservoirs contain pores with size mostly ranging between 0.01 and 0.1 μm, followed by pores with size range of 0.001–0.01 μm, and relatively fewer pores larger than 0.1 μm. The Type-B reservoirs are carbonate rocks with extremely heterogeneous pore size distribution, which is closely related to the development of dissolution pores and microfractures. Type-C sandstone reservoirs are dominated by nanopores and submicron pores that distribute more heterogeneously than pores in Type-A reservoirs. The pore distribution in sandstone reservoirs shows significant fractal characteristics and is closely related to the pore size. The heterogeneity of nanopore distribution has a negative correlation with porosity and median pressure and a relatively weak correlation with permeability. Our study has important implications for petroleum exploration in the South Yellow Sea Basin.

Disentangling Combined Effects of Sediment Sorting, Provenance, and Chemical Weathering From a Pliocene‐Pleistocene Sedimentary Core (CSDP‐1) in the South Yellow Sea

AbstractThe South Yellow Sea is an important sink for sediments delivered by the Yellow and Yangtze rivers in East Asia. We conducted a high‐resolution geochemical analysis on the bulk sediments retrieved from a marine drill core (CSDP‐1) using the method of X‐ray fluorescence (XRF). Our results show large geochemical variations along the core. As demonstrated by linear correlations along with the Al‐Si link in a compositional principal component analysis (PCA), the variations in elemental ratios among Al, K, Zr, Ba, and Si are primarily controlled by sediment sorting effects. A closer examination indicates a gradual shift of sediment provenance from the Yangtze to the Yellow River catchment in the core. With the help of a fuzzy c‐means cluster analysis on elemental ratios of Al/Si, Al/Ti, K/Si as well as the chemical index of alteration (CIA), the timing of a major provenance change in the core is narrowed down to 1.5–1.7 Ma. This timing corresponds to a major seismic and sedimentary boundary (T2) in the Yellow Sea Basin and coincides with the onset of fluvial terrace deposition and incision in the middle and upper reaches of the Yellow River. As a result, we argue that the major provenance change derived from geochemical variations in the Yellow Sea sedimentary basin can be linked with the integration of the modern Yellow River. The provenance change is likely caused by a coupling between regional tectonic deformation and the Asian summer monsoon enhancement in the early Pleistocene.

Tropical cyclone-induced sea surface cooling over the Yellow Sea and Bohai Sea in the 2019 Pacific typhoon season

Shallow water response and feedback to tropical cyclones (TCs; known as typhoons in the northwest Pacific) play an important role in modulating TCs' landfall intensity. In the 2019 Pacific typhoon season, four TCs, i.e., Danas in July, Lekima in August, Lingling in September and Mitag in October, traversed and influenced the vast shallow waters of the Yellow Sea (YS) and the Bohai Sea (BS). Based on satellite and in situ buoy observed sea surface temperature (SST) datasets and numerical experiments, in this study, we examined and contrasted the SST responses of the YS and BS shallow waters to these four TCs. Compared to the other three TCs, Lekima with relatively weaker intensity, induced the largest (up to 5.5 °C) and most widespread SST cooling over the whole YS basin, which was attributed to the most stratified and sharpest thermal structure in August based on numerical experiments. The model results also suggest an SST cooling limitation in the condition the whole shallow water column has been well mixed. The buoy observations indicate that more than 80% of the TC-induced SST cooling occurred ahead of the TC eye centre approaching. The TC also contributes significantly to the SST seasonal cycle of coastal waters by disrupting the seasonal SST evolution in several hours and lasting for tens of days.

Geochemistry of the upper Permian sandstones in the Dalong Formation in the South Yellow Sea Basin, East China: implications to provenance, weathering, and tectonic setting

Geochemistry of the upper Permian sandstones in the Dalong Formation in the South Yellow Sea Basin, East China: implications to provenance, weathering, and tectonic setting

Characteristics of Milankovitch cycles recorded in Eocene strata in the eastern depression of North Yellow Sea Basin, North China

As cyclical orbital movements of Earth, Milankovitch cycles can be recorded in sedimentary strata. The time they reflect can be used to accurately divide and compare strata. Milankovitch cycles recorded in strata enrich the stratigraphic theory, especially the theories of cycle stratigraphy, and thus they are widely used in geological survey engineering nowadays. This study explored the characteristics of the Milankovitch cycles recorded in the eastern depression of the North Yellow Sea Basin, highlighting their control over high-frequency stratigraphic sequences. The Eocene Milankovitch cycles in the depression were calculated based on the method proposed by J. Laskar, and their parameters primarily include eccentricity cycles of 125 ka and 99 ka, obliquity cycles of 51 ka and 39 ka, and precession cycles of 23 ka and 19 ka. Spectral analysis of gamma-ray (GR) and spontaneous potential (SP) log curves of the Eocene strata was carried out to divide and compare stratigraphic sequences, revealing that the spectral peaks correspond well to astronomical cycles. This indicates that the strata in the depression fully record Milankovitch cycles. Furthermore, there are long-, medium-, and short-term stratigraphic cycles in the eastern depression, with a thickness of 13.03–15.89 m, 3.70–5.21 m, and 2.17–2.94 m, respectively. The sedimentation rates of the Eocene strata were calculated to be 121.2–127.12 m/Ma accordingly. From the uplift to the center of the lacustrine basin along the slope in the eastern depression, both the sedimentation duration and the sediment thickness increase, while the sedimentation rate remains relatively stable. The Eocene strata can be divided into six stages of high-frequency sequences by continuous wavelet transformation, namely E6–E1 from bottom to top. The sedimentation duration and sedimentation rates of the sequences were calculated using spectral analysis with each of the sequences as a separate window. Moreover, the impacts of climate change on the sedimentary environment in the eastern depression were analyzed. It can be concluded that E6 was a lowstand system tract, E5 and E4 were lacustrine expansion system tracts, E3 was a highstand system tract, and E2 and E1 were lacustrine contraction system tracts. All these verify that Milankovitch cycles serve as an effective approach for the analysis of sedimentary cycles.

Cenozoic tectonic inversion in the Northern Depression, South Yellow Sea Basin, East Asia: Structural styles and driving mechanism

The Northern Depression of the South Yellow Sea Basin underwent two episodes of tectonic inversion from the latest Eocene to Oligocene and in the Pliocene, respectively. During the inversion, the structural depression controlled previously by extensional faults was subjected to compression and erosion. Structural interpretation on 2D marine seismic data suggests that the structural styles associated with inversion are predominantly reactivated NNW-trending faults, fault-related folds, newly-formed reverse faults and unconformities. Here we used structural restoration technique to illustrate the sequential development of these inversion structures and to estimate the amount of deformation. To explore the mechanism of the basin inversion, the finite element modeling was employed to reproduce the inversion deformation in the Northern Depression. The deformation features predicted by modeling are well consistent with our structural observations. Based on a combination of these results and regional tectonic history, we propose that the inversion deformation in the South Yellow Sea Basin was predominantly driven by the enhanced dextral strike-slip motion along the Tan-Lu Fault. The interactions between the Eurasian plate and the Pacific realm resulted in the varying dextral movement along the Tan-Lu Fault, and the Cenozoic tectonic inversion in the South Yellow Sea Basin was a tectonic response to these processes.

Chronology of a sedimentary sequence from the land–ocean interaction zone in the North Jiangsu Basin

The North Jiangsu Basin (NJB), located in the western part of the North Jiangsu-South Yellow Sea Basin, is a critical region providing invaluable archives about the evolution processes of the land-ocean interchange and climatic environments in a coastal zone. Chronology is of crucial importance to reconstruct the timing of sea-level eustacy, and shoreline changes, as well as the evolution of the regional environment by means of numerical dating to determine the age of sedimentary strata in the sea–land interaction zone of the NJB. However, sediment dating in the NJB remains controversial due to limitations in the quantity and quality of chronological data. Therefore, the sediments in the Jianhu Gangxi (GX) profile of the NJB were analyzed in this study by applying both fine-grained quartz optically stimulated luminescence (OSL) dating and 14C dating. The results were used to discuss the processes of regional environment evolution. The OSL dating of fine-grained quartz components in sediments was found to be a reliable method to determine deposition ages of sediments in the land-sea interaction zone in the NJB. The combination of OSL and accelerator mass spectrometry 14C dating techniques allowed a reliable and high-resolution chronological framework for the GX profile. Since the last glaciation, the sedimentary environment in the eastern portion of the NJB changed significantly. In particular: (1) between 13 and 7.25 ka B.P, the area of interest was dominated by lacustrine deposition within a stable sedimentary environment with low deposition rates; (2) from 7.25 to 6.45 ka B.P, marine transgression events occurred, and the deposition rate increased rapidly in an area of land-sea interaction; (3) after 6.45 ka B.P, a regression event occurred, and the study area transformed into a lowland lake environment.

The present-day Yangtze River was established in the late Miocene: Evidence from detrital zircon ages

Abstract 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.

The Late Jurassic to Early Cretaceous Strike‐Slip Faults in the Subei‐South Yellow Sea Basin, Eastern China: Constraints From Seismic Data

AbstractLate Jurassic‐Early Cretaceous strike‐slip faults play an important role in basin formation and igneous activities in eastern China and the adjacent areas. Because of the lack of seismic data, their distribution and effect on the formation of basins and igneous activities in the Subei‐South Yellow Sea Basin (SB‐SYSB) are still poorly understood. In this study, based on systematic analyses of the acquired seismic data, the Late Jurassic‐Early Cretaceous strike‐slip faults in the SB‐SYSB were identified and characterized. The strike‐slip faults can be divided into two sets, a NE‐NNE trending sinistral strike‐slip fault system and a NW trending dextral fault system. They present in seismic sections as a flower structure or Y/V‐shaped structure, respectively. In map view, they show horsetail splay faults, en echelon reverse faults, pull‐apart structure, linear structure, or curvilinear structure. These faults resulted in different types of subbasins in the SB‐SYSB, such as transpressional/transtensional subbasins and pull‐apart subbasins. The close relationship between the strike‐slip faults and the distribution of igneous rocks in the SB‐SYSB suggest that the strike‐slip faults probably acted as efficient pathways for magma intrusion during the Late Jurassic‐Early Cretaceous. The sinistral displacement was characterized by thrusting‐folding deformation structures, which show a tendency to decrease toward the Sulu orogenic belt, indicating that the Sulu orogenic belt has probably weakened the strike‐slip movement in the basin. We infer that the sinistral strike‐slip movement in the SB‐SYSB was most likely controlled by the subduction of the paleo‐Pacific plate and the Tan‐Lu strike‐slip faulting.