Carbon Storage Dynamics in Lower Shimentan Formation of the Qiantang Sag, East China Sea Shelf Basin: Stratigraphy, Reservoir ‒ Cap Analysis, and Source ‒ Sink Compatibility

Excessive carbon emissions have resulted in the greenhouse effect, causing considerable global climate change. Marine carbon storage has emerged as a crucial approach to addressing climate change. The Qiantang Sag(QTS) in the East China Sea Shelf Basin, characterized by its extensive area, thick sedimentary strata, and optimal depth, presents distinct geological advantages for carbon dioxide(CO_(2)) storage. Focusing on the lower section of the Shimentan Formation in the Upper Cretaceous of the QTS, this study integrates seismic interpretation and drilling data with core and thin-section analysis. We reveal the vertical variation characteristics of the strata by providing a detailed stratigraphic description. We use petrophysical data to reveal the development characteristics of high-quality carbon-storage layers and favorable reservoircaprock combinations, thereby evaluating the geological conditions for CO_(2) storage in various stratigraphic sections. We identify Layer B of the lower Shimentan Formation as the most advantageous stratum for marine CO_(2) storage. Furthermore, we analyze the carbon emission trends in the adjacent Yangtze River Delta region. Considering the characteristics of the source and sink areas, we suggest a strong correlation between the carbon emission sources of the Yangtze River Delta and the CO_(2) storage area of the QTS, making the latter a priority area for conducting experiments on marine CO_(2) storage.

Sedimentary systems of the Oligocene Huagang Formation in the central anticline zone of the Xihu Depression,East China Sea Shelf Basin

The Xihu Depression is the largest hydrocarbon-bearing depression of the East China Sea Shelf Basin(also referred to as the ECSSB).However,the depositional systems and reservoir distribution of the Oligocene Huagang Formation in the Xihu Depression are still controversial.Under the guidance of sedimentology and stratigraphy,this study documented a marine-terrestrial transitional environment in the restricted bay setting of the Oligocene Huagang Formation through core description,well logging,and seismic data analysis.This study also revealed that the Oligocene Huagang Formation is dominated by tidal delta,estuary,and gravity flow deposits in the central anticline zone of the Xihu Depression.The new understanding of the sedimentary systems and the discovery of the transgressive gap in the eastern Diaoyu Islands uplift explain the origin of fine-grained sediments and the EW-trending sand bodies in the central depression and the sand bodies parallel to shoreline in the west slope belt,which cannot be explained by previous study results,such as southern transgression or fluvial deltas and even lacustrine deposition.Moreover,the tidal channels,tidal sand flats,and gravity flow sand bodies formed by the transgressive tides are high-quality reservoirs.The study will provide a basis for well placement and serve as guidance for the selection of favorable hydrocarbon exploration areas in the Xihu Depression.

Environmental record from the mud area on the inner continental shelf of the East China Sea since the mid-Holocene

Paleoclimate record was revealed in Core MZ01 covering the mid-Holocene in age,located in the mud area of the inner continental shelf of the East China Sea. The ancient environment featured low-energy shallow sea shelf deposition formed mainly by coastal currents. The results show that temporal variation in geochemistry corresponds with the climate changes inferred from historical record. Relatively low MgO/Al 2 O 3,CaO/K 2 O and high Al 2 O 3 /Na 2 O,K 2 O/Na 2 O,MnO/CaO values reflected a warm and humid climate in general,and vice versa. Therefore,these chemical indices could be applied to identify the variation of palaeoclimate in eastern China. The authors reconstructed the history of mid-Holocene climatic variation of the inner continental shelf of the East China Sea. From 8 300 a BP to 4 200 a BP,the climate was moderately warm and humid. From 4 200 a BP to 2 000 a BP,the climate turned cool and dry,and the regional climate frequently fluctuated in alternation of cool-dry periods（3 700 a BP,2 850 a BP and 2 400 a BP） and warm-wet periods（3 250 a BP and 2 650 a BP） . After 2 000 a BP,the climate of the study area gradually turned warm again,while the Little Ice Age,a cold event centered at around 250 a BP was indicated by those geochemical indices as mentioned above.

The Mesozoic Basin-Mountain Coupling Process of the Southern East China Sea Shelf Basin and its Adjacent Land Area

Basin-mountain coupling is a key issue for basin formation and evolution. The analysis of basin-mountain coupling process, as well as quantitative or semiquantitative restoration of prototype basin and the evolution of continental margin, can be used to interpret the geological process of basin-range conversion and reconstruct early prototype basins, which is a difficult and leadin~ scientific oroblem of basin research.

Nutrient dynamics and cross shelf transport in the East China Sea

To understand the temporal and spatial variations in nutrient dynamics,as well as the potential cross-shelf transport of nutrients between the East China Sea(ECS)shelf and the northwestern Pacific Ocean,six field observations covering the ECS were conducted in spring,summer,and autumn in 2011 and 2013.Nutrient dynamics in the ECS and nutrient exchange between shelf water and the open ocean were examined.High concentrations of dissolved inorganic nutrients were detected in the nearshore surface layer and offshore bottom layer in different seasons,and the concentrations of dissolved inorganic nutrients in surface seawater were lower in summer and autumn than in spring.The concentrations of dissolved organic nutrients in Kuroshio surface water were slightly lower in summer than in spring,but the concentrations in Kuroshio subsurface water were slightly higher in summer than in spring.There were abundant nutrient reservoirs in the euphotic zone of the ECS,which explained the high primary productivity.The evaluation of cross-shelf transport indicated that nutrients from shelf water were transported out across the 200 m isobath through the surface layer with the density(σ)less than 23.0 kg/m^(3) in spring.The flux of dissolved inorganic nitrogen transported from the ECS shelf to the Northwest Pacific Ocean in spring was equivalent to 21%of the atmospheric nitrogen deposition in the Northwest Pacific Ocean.In summer,the onshore flux in the surface and bottom layers accounted for 80%of the total flux,and the transportation of nutrients along the surface layer to the continental shelf contributed to the nutrient storage and primary productivity of the euphotic zone in the ECS shelf in summer.

Response of environmental sensitive grain size group in Core FJ04 from mud area in the north of East China Sea to East Asian winter monsoon evolvement

AMS14C dating and grain-size analysis for Core FJ04, located at mud area in the North of East China Sea provide us a high-resolution grain-size distribution curve varying with depth and time. This paper got environmental sensitive grain-size group by using standard deviation method, and proved that the selected sensitive grain-size group is an important proxy which can be used to reconstruct intensity of East Asian Winter Monsoon （EAWM）. Then we got reconstruction of EAWM evolvement since 3 ka B.P., which revealed two main phases： （1） 3 - 1.15ka B.P., relative weak EAWM with middle frequency fluctuation; （2） 1.15 - 0ka B.P., really strong EAWM with high frequency fluctuation. And 1.15 ka B.P. is a distinct turning point. During the whole period, 11 intense events of EAWM were recorded and correlated well with other climate records, but the response extent was different, which showed consistency of climate change and particularity of region response.

Transport patterns of micro nutrient elements from the continental shelf of the East China Sea to the Kuroshio area

On the basis of the in situ data of DO2, pH, SiO2. PO4-P, NO3-N and NO2-N collected in the north of the East China Sea during 1987-1988, the following points are mainly expounded.1.The inorgonic nutrients are obviously affected by continent runoff in the north of the East China Sea. Their distributions are characteristic of its distribution of terrigenous materials.2.There are three transport paths of nutrients from the shelf to the Kuroshio area. The first is mixing-diffusing-advec-tion and upwelling process, the process of biology and biochemistry belongs to the second, and the sinking process is the last one.3.The swing of the Kuroshio axis affectes both the range of the migration of substances through mixing-diffusing-advec-tion process and the upwelling degree of the subsurface Kuroshio water to the shelf.4.Most part of the substances sink as macroparticles to the deep layer before reaching the Kuroshio area.

Geochemical and isotopic characteristics of volcanic rocks from the northern East China Sea shelf margin and the Okinawa Trough

Volcanic rocks both from the northern East China Sea （NECS） shelf margin and the northern Okinawa Trough are subalkaline less aluminous,and lower in High Field Strength Elements （HFSE）.These rocks are higher in Large Ion Lithophile Elements （LILE）,thorium and uranium contents,positive lead anomalies,negative Nb-Ta anomalies,and enrichment in Light Rare Earth Elements （LREE）.Basalts from the NECS shelf margin are akin to Indian Ocean Mid-Ocean Ridge Basalt （MORB）,and rhyolites from the northern Okinawa Trough have the highest 207 Pb/ 204 Pb and 208 Pb/ 204 Pb ratios.The NECS shelf margin basalts have lower 87 Sr/ 86 Sr ratios,ε N d and σ 18 O than the northern Okinawa Trough silicic rocks.According to 40 K– 40 Ar isotopic ages of basalts from the NECS shelf margin,rifting of the Okinawa Trough may have been active since at least 3.65–3.86 Ma.The origin of the NECS shelf margin basalt can be explained by the interaction of melt derived from Indian Ocean MORB-like mantle with enriched subcontinental lithosphere.The basalts from both sides of the Okinawa Trough may have a similar origin during the initial rifting of the Okinawa Trough,and the formation of basaltic magmas closely relates to the thinning of continental crust.The source of the formation of the northern Okinawa Trough silicic rocks was different from that of the middle Okinawa Trough,which could have been generated by the interaction of basaltic melt with an enriched crustal component.From the Ryukyu island arc to East China,the Cenozoic basalts have apparently increasing trends of MgO contents and ratios of LREE to Heavy Rare Earth Elements （HREE）,suggesting that the trace element variabilities of basalts may have been influenced by the subduction of the Philippine Sea plate,and that the effects of subduction of the Philippine Sea plate on the chemical composition of basaltic melts have had a decreasing effect from the Ryukyu island arc to East China.

Diagenesis and Diagenetic Evolution of Deltaic and Neritic Gas-Bearing Sandstones in the Lower Mingyuefeng Formation of Paleogene, Lishui Sag, East China Sea Shelf Basin: Implications for Depositional Environments and Sequence Stratigraphy Controls

Gas-bearing deposits in the Lower Mingyuefeng Formation of Paleogene, Lishui Sag, East China Sea Shelf Basin consist of shoreface sandstones of the highstand systems tract（HST） and transgressive systems tract（TST）, and deltaic sandstones of the lowstand systems tract（LST） and falling stage systems tract（FSST）.Detailed petrographic observations suggest that the diagenetic features and related evolution of these deposits cannot be simply characterized and demonstrated in the depth domain.However, the occurrence of diagenetic minerals systematically depends on the studied interval within the HST, TST, LST, and FSST; therefore, diagenesis in this region can be better constrained when studied in the context of the depositional environments and sequence stratigraphic framework.The eogenetic processes in such settings include：（1） microcrystalline siderite precipitated as concretions in almost all environments and systems tracts, which inhibited further mechanical compaction;（2） grain dissolution and kaolinitization occurred in shoreface HST sandstones and deltaic LST and FSST sandstones;（3） glaucony was locally observed, which did not clearly reflect the controls of facies or sequence stratigraphy; and（4） cementation by pyrite aggregates occurred in the shoreface HST sandstones and deltaic LST sandstones.The mesogenetic diagenesis includes：（1） partial conversion of kaolinite into dickite in deltaic LST sandstones, and minor chlorite cementation in deltaic FSST sandstones;（2） transformation of kaolinite into illite and quartz cementation in deltaic LST and FSST sandstones;（3） frequent precipitation of ankerite and ferroan calcite in shoreface TST sandstones and early HST sandstones, forming baffles and barriers for fluid flow, with common calcite in shoreface HST sandstones as a late diagenetic cement; and（4） formation of dawsonite in the deltaic LST and FSST sandstones, which is interpreted to be a product of the invasion of a CO2-rich fluid, and acts as a good indicator of CO2-bearing reservoirs.This study has thus constructed a reliable conceptual model to describe the spatial and temporal distribution of diagenetic alterations.The results may provide an entirely new conceptual framework and methodology for successful gas exploration in the continental margins of offshore China, thus allowing us to predict and unravel the distribution and quality evolution of clastic reservoirs at a more detailed and reliable scale.

Tectonics and Petroleum Potential of the East China Sea Shelf Rift Basin

There are two Cenozoic sedimentary basins in the East China Sea. They are the East China Sea shelf basin and the Okinawa Trough basin. The former can be divided into a western and an eastern rift region. The development of the shelf basin underwent continental-margin fault depression, post-rift and then tectonic inversion stages. Available exploration results show that the distribution of source rocks is controlled by the basin architecture and its tectonic evolution. In the Xihu depression, mudstones and coals are the main source rocks. The eastern rift region has good geological conditions for the formation of large oil and gas fields.

Measurement of the current and spectral analysis on the continental shelf in the East China Sea

Direct measurements of current velocity and water temperature were undertaken at the mooring Sta. M (125°29.38' N, 31°49.70' E) on the continental shelf area in the East China Sea in June 1999 by R/V Xiangyanghong 14. The relationship between various time series of oceanic fluctuations is calculated by spectral analysis. The major results are as follows: (1) an average (u,v) of (6.9,-3.0 cm/s) at the 30 m depth is obtained during the 9-day observation, and that at the 45 m depth is (3.7,-1.1 cm/s), i. e., the mean flows are southeastward at both the 30 and 45 m depths;the currents become stronger gradually during the observation period; this may be mainly attributed to the transition of the tidal currents from neap to spring; (2)semidiurnal fluctuation is the most dominant in the current fluctuations, and rotates mainly clockwise; in the next place, there is also diurnal fluctuation;the local inertial period is close to the period of diurnal fluctuation, and an inertial motion is clockwise; thus, local inertial motion combines with diurnal fluctuation, and makes the spectral peaks in clockwise components much higher than those in counterclockwise ones; except for the fluctuations of above main periods, there is also the peak at 3 d period for counterclockwise compo-nents in the upper and lower layers; (3) the calculation of cross spectra between two time series of current velocities at the 30 and 45 m depths shows that both the current fluctuations at the 30 and 45 m depths are much alike, i. e., they are synchro; this shows that the flow field here is rather vertically homogeneous; (4)power spectra of tempera-ture time series at both the 30 and 45 m depths show that the semidiurnal peak is the most predominant, and the second highest peak is the diurnal period; besides spectral peaks at above periods, there are also obvious spectral peaks at 6.8 h and 2 d; (5)plots of temperature time series at 16 , 30 , 35 , 45 and 50 m depths show that the temporal variations of temperature at these depths are synchro, which are like those in the velocity field; temperature records also show a gradual rise in temperature, which are also like those in the velocity field.

TRANSPORT OF SUSPENDED MATTER FROM THE CHANGJIANG RIVER TO THE EAST CHINA SEA SHELF

Suspended matter (SM) in the East China Sea (ECS) shelf seawater was investigated during Oct. 1993, Apr. and Oct. 1994. Results showed that the high total suspended matter(TSM) region (>7200)mg/L) was limted to near the estuary and reduced rapidly to <10 mg/L at 122 °30’E. The high TSM contour extended mainly NE in surface water but SE in near bottom Water,i. e., SM transport from the Changjiang River was characterized by "stratification and different transport directions in different layers’. TSM distribution on sections showed that the up-climbing Kuroshio water prevents Changjiang River SM in middle and bottom water from transporting to the Okinawa Trough. Vertical distributions of the TSM showed a suspended-cline that appeared in the inner and middle shelf TSM below it was dense and formed a turbid water laper, TSM above it was less dense, so the water was reatively clear. Formation of the suspended-cline correlated with high density current and resuspension of bottom sediment.

Temporal-Spatial Variation of Surface Suspended Matter and Controlling Factors in the Inner Shelf of the East China Sea in Winter

Based on the observed surface suspended matter in the East China Sea in February 2007 and June 2015, an empirical model was established using L1 b's band 4 data to retrieve surface suspended matter from the Moderate Resolution Imagine Spectroradiometer Terra imagery. The squared correlation coefficient is 0.8358, and the root mean square error is 0.4285 mg L-1. The model reflects the distribution characteristics of surface suspended matter in the inner shelf of the East China Sea. In this paper, the satellite images of the study area were retrieved in January from 2001 to 2015, and the monthly distribution of surface suspended matter were obtained. The inter-annual distribution of the study area is similar, and the concentration of surface suspended matter is higher near the shore than offshore. A large amount of surface suspended matter is transported southeast under the influence of Zhejiang and Fujian coastal current and Taiwan warm current. Only a small amount of surface suspension can reach the Kuroshio area. The surface suspended matter concentration changes obviously near the estuary because of the effect of differences in the flux of the Yangtze River. Meanwhile, winter monsoon, temperature front, El Ni?o events, and other factors affect the distribution of surface suspended matter in 100 m isobath to coastal water but minimally influence the distribution in 100 m isobath to deep sea.

Distribution of Dissolved Inorganic Arsenic and Its Seasonal Variations in the Coastal Area of the East China Sea

Water samples were collected in the coastal area of the Changjiang Estuary on four cruises from August 2002 to May 2003. The seasonal variations of dissolved inorganic arsenic （DIAs） distributions were analyzed. The results showed that the distributions of DIAs were mainly influenced by Water （KSSW）. The concentration of the total dissolved the terrestrial input and the intrusion of the Kuroshio Subsurface inorganic arsenic （TDIAs） decreased consecutively from winter to summer, while it increased in autumn. The distributions of TDIAs showed some relationships with salinity and suspended particulate matter （SPM）. The relationships between DIAs speciation （including arsenite [ As（ Ⅲ ） ] and arsenate [ As（ Ⅴ ） ]）, biological activity and the availabilities of the phosphate were investigated in the study area for the cruise August 2002. The ratio of As （Ⅲ）/TDIAs increased with the decrease of phosphate concentrations. In the bottom water, the As（ Ⅲ ）/TDIAs ratio decreased with the increasing of N/P. The concentration of TDIAs decreased 28.7% approximately after the occurrence of harmful algal blooms （HAB） because of the uptake of arsenate by algae. Further study is needed about the arsenic source/sink relationships in their vertical or horizontal profiles and the uptake mechanism during the occurrence of harmful algal blooms.

pCO_2 distribution and CO_2 flux on the inner continental shelf of the East China Sea during summer 2011

Measurements ofpH, total alkalinity （TA）, partial pressure of CO2 （pCO2） and air-sea CO2 flux （FCO2） were conducted for the inner continental shelf of the East China Sea （ECS） during August 2011. Variations in pCO2 distribution and FCO2 magnitude during the construction of the Three Gorges Dam （TGD） （2003-2009）, and the potential effects of the TGD on the air-sea CO2 exchange were examined. Results showed that the ECS acts as an overall CO2 sink during summer, with pCO2 ranging from 107 to 585 p.atm and an average FCO2 of -6.39 mmol/（m2·d）. Low pCO2 （〈350 μatm） levels were observed at the central shelf （28°-32°N, 123°-125.5°E） where most CO2-absorption occurred. HighpCO2 （〉420 μatm） levels were found in the Changjiang estuary and Hangzhou Bay which acted as the main CO2 source. A negative relationship between pCO2 and salinity （R2=0.722 0） in the estuary zone indicated the predominant effect of the Changjiang Diluted Water （CDW） on the seawater CO2 system, whereas a positive relationship （R2=0.744 8） in the offshore zone revealed the influence of the Taiwan Current Warm Water （TCWW）. Together with the historical data, our results indicated that the CO2 sink has shown a shift southwest while FC02 exhibited dramatic fluctuation during the construction of the TGD, which is located in the middle reaches of the Changjiang. These variations probably reflect fluctuation in the Changjiang runoff, nutrient import, phytoplankton productivity, and sediment input, which are likely to have been caused by the operations of the TGD. Nevertheless, the potential influence of the TGD on the CO2 flux in the ECS is worthy of further study.

Characteristics and evaluation of Mesozoic source rocks in the southeastern East China Sea continental shelf

Source rocks are the material basis of oil and gas generation and determine the potential resources of exploration blocks and have important research value. This paper studies the lithology, thickness, and geochemistry of Mesozoic source rocks in the southeastern East China Sea continental shelf. The results show that the Mesozoic source rocks are mainly dark mudstone and coal-bearing strata. The total thickness of Lower–Middle Jurassic source rocks ranges from 100 m to 700 m, and that of Lower Cretaceous source rocks ranges from 50 m to 350 m. The overall thickness of Mesozoic source rocks is distributed in the NE direction and their thickness center is located in the Jilong Depression. The Lower–Middle Jurassic source rocks are mainly developed shallow marine dark mudstone and transitional coal measure strata. Those of the Lower Cretaceous are mainly mudstone of a fan delta front. Lower –Middle Jurassic and Lower Cretaceous hydrocarbon source rocks are dominated by type III kerogen, with Lower –Middle Jurassic hydrocarbon source rocks having high organic matter abundance and being medium –good hydrocarbon source rocks, while Lower Cretaceous hydrocarbon source rocks have relatively poor quality. From northwest to southeast, the vitrinite reflectance Ro of Mesozoic source rocks increases gradually. Source rocks in the study area are divided into three types. The first hydrocarbon-generating area is mainly located in the southeastern region of the study area, and the Jilong Depression is the hydrocarbongenerating center. The results of this study can provide a basis for exploration of Mesozoic oil and gas resources in the southeastern East China Sea continental shelf.

A probe heat flow value of the East China Sea shelf

Bottom temperature variation (BTV) is a serious problem in determining the thermal gra- dient and heat flow of the sediments in shallow seas. The water depth of the East China Sea shelf is mostly below 150m, and the heat flow measurement is strongly affected by BTV. Following a statistical algorithm, we rechecked the temperature and thermal conductivity data of the cruises KX90-1 and KX91-1, carried out by a cooperation program of China and Japan, and calculate the heat flow in a site without long-term temperature record. The calculated heat flow in the site was 58.6±3.6 mW/m2, being just within the range of the drill heat flow value of East China Sea shelf. The inversed amplitude spectrum of BTV has a peak in frequency of 1/10 per year, and the annual component is also an important part. Comparison with two lakes of Lake Greifensee and Lac Leman (i.e. Lake Geneva), which are in different water depth, revealed that with increasing water depth, the peak of amplitude spectrum moved towards low frequency components. The heat flow values calculated in this paper and from petroleum bore hole in East China Sea shelf are much more close to that in southeast China than in Okinawa Trough.

Paleo-fluvial sedimentation on the outer shelf of the East China Sea during the last glacial maximum

Evidence from lithology, foraminiferal assemblages, and high-resolution X-ray fluorescence scanning data of core SFK-1 indicates tidally influenced paleo-fluvial sedimentation during the last glacial maximum (LGM) on the outer shelf of the East China Sea. The paleo-fluvial deposits consist of river channel facies and estuarine incised-valley-filling facies. Different reflections on the seismic profile across core SFK-1 suggest that the river channels shifted and overlapped. River channel deposition formed early in the LGM when sea level fell and the estuary extended to the outer shelf. Channel sediments are yellowish- brown in color and rich in foraminifera and shell fragments owing to the strong tidal influence. Following the LGM, the paleo-river mouth retreated and regressive deposition of estuarine and incised-valley-filling facies with an erosion base occurred. The river channel facies and estuarine incised-valley-filling facies have clearly different sedimentary characteristics and provenances. The depositional environment of the paleo-river system on the wide shelf was reconstructed from the foraminiferal assemblages, CaCO3 content and Ca/Ti ratio. The main results of this study provide further substantial constraints on the recognition of late Quaternary stratigraphy and land-sea interactions on the ECS shelf.

Vertical Structure of the Tidal Currents on the Continental Shelf of the East China Sea

The available data on tidal currents spanning periods greater than six months for the continental shelf of the East China Sea (26°30.052′N, 122°35.998′E) were analyzed using several methods. Tidal Current Harmonic Analysis results demonstrated that semi-diurnal tides dominated the current movement. The tidal currents of the principal diurnal and semidiurnal rotated clockwise with depth, with the deflection of the major semi-axes to the right in the upper layer and to the left in the lower layer. The vertical structures of two principal semi-diurnal constituents-M2 and S2-were similar, which indicates that the tidal currents are mainly barotropic in this area. The main features of the variation of the four principal tidal constituents with depth demonstrate that the currents in this region are influenced by the upper and lower boundary layers. Therefore, the tidal constituents of the shallow water are similar. Different vertical modes were calculated based on the Empirical Orthogonal Function (EOF) analysis of the Eastern and Northern components of the tidal currents, with a variance contribution for the zero-order model of at least 90%. The variance contribution of the baroclinic model is minimal, which further reveals a strong barotropic character for the tidal currents of this region.

New interpretation on the provenance changes of the upper Pinghu–lower Huagang Formation within Xihu Depression,East China Sea Shelf Basin

Both Pinghu and Huagang formations are important hydrocarbon reservoirs of the Xihu Depression in the East China Sea Shelf Basin.Clarifying the source suppliers and restoring source-to-sink transport routes are of great significance to the future petroleum and gas undertakings.Previous researchers were largely confined by either limitation of geological records,highly dependence on a singular method or low-precision dating techniques.Our study integrated heavy mineral assemblages,geochemical analyses and detrital zircon U-Pb dating to reconstruct multiple source-to-sink pathways,and to provide a better understanding on the provenance evolution for the upper Pinghu–lower Huagang depositions of the Xihu Depression.At least three major provenances have been confirmed and systematically investigated for their separate compositional features.The Hupijiao Uplift(or even farther northern area)was dominated by a major Paleoproterozoic population peaked at ca.1830 Ma along with minor Mesozoic clusters.The Haijiao Uplift to the west and the Yushan Low Uplift to the southwest,on the other hand,generate opposite U-Pb age spectra with apparently larger peaks of Indosinian and Yanshanian-aged zircons.To be noted,both Indosinian and Paleoproterozoic peaks are almost identical in proportion for the Haijiao Uplift.The overall sedimentary pattern of late Eocene-early Oligocene was featured by both spatial and temporal distinction.The Hupijiao Uplift was likely to cast limited impact during the late Eocene,whereas the broad southern Xihu Depression was transported by a large abundance of materials from the nearby Haijiao and Yushan Low Uplifts.The northern source substantially extended its influence to the farther south during the early Oligocene by delivering plentiful sediments of higher-degree metamorphic parent rocks.Combined with the proximal western and southwestern suppliers,the overall Xihu Depression was under control from both distant and local provenances.