Reconstructed synsedimentary paleogeomorpholgy is an effective method in predicting the distribution of sandbodies and can provide valid evidence in the search for reservoirs. Based on a synsedimentary paleogeomorphol...Reconstructed synsedimentary paleogeomorpholgy is an effective method in predicting the distribution of sandbodies and can provide valid evidence in the search for reservoirs. Based on a synsedimentary paleogeomorpholgy reconstruction of the third member of the Dongying formation (Ed3) in the Qikou sag,the basic paleogeomorphic characteristics of Ed3 are described and the spatial distributions of denudation and subsidence areas are discussed. Key boundary faults controlling the deposition of important sediment bodies are proposed and the interrelations among faulted slope-break belts or flexure belts,intra-depression uplifts and sags,sediment sources and sediments input points have been investigated.展开更多
Huhehu Sag is a new battlefield for the future oil and gas exploration in the Hailar Basin. At present, exploration of this area stays at a low level and the understanding of the provenance system of the Nantun Format...Huhehu Sag is a new battlefield for the future oil and gas exploration in the Hailar Basin. At present, exploration of this area stays at a low level and the understanding of the provenance system of the Nantun Formation is comparatively weak. So, to carry out the detailed depiction of the provenance system in the study area is significant for the sedimentary system reconstruction, for the prediction of reservoir distribution and favorable areas. Based on comprehensive analysis of paleogeomorphy, light-heavy mineral and seismic reflection features, sandstone thickness and sandstone percentage, this paper analyzes in detail the provenance system of the Nantun Formation in Huhehu Sag from various angles and levels. It shows that provenances of the Huhehu Sag mainly originated from the eastern Xilinbeier Salient and western Bayan Mountain Uplift. The provenances surrounding the lake basin converged to the center of the basin, among which, the steep slope belt and the gentle slope belt are the main provenances, and the southern uplift is a secondary one. The distribution framework of the provenance fundamentally determines the distribution rules of the depositional system and its sand body developing during the Nantun period.展开更多
The sedimentary geochemistry of St.Martin’s Island is important to determine the origin of the source rock,paleo weathering,tectonic setting,sediment recycling,maturity,sorting,redox condition,and paleo salinity of t...The sedimentary geochemistry of St.Martin’s Island is important to determine the origin of the source rock,paleo weathering,tectonic setting,sediment recycling,maturity,sorting,redox condition,and paleo salinity of the sediments.Major oxides,trace elements,and rare earth elements(REEs)obtained from the INAA technique are presented by analyzing the sediment samples collected from the shoreline of St.Martin’s Island,Bangladesh.The elemental ratios,comparison with average upper continental crust(UCC),binary diagrams(Th/Sc vs.Sc,La/Th vs.Hf,Th/Co vs.La/Sc),and chondrite normalized REE patterns exhibit substantial LREE enrichment,relatively fl at HREE fractionation,considerable negative Eu anomalies(average:0.72),indicates the derivation from a source dominated by felsic rock,with contribution from intermediate source and mafi c component.Sediments from St.Martin’s Island exhibit the deposition of sediments in transitional environments of active and passive continental margin settings.Weathering indices value of CIA,PIA,CIW,CIX,and K 2 O/Rb ratio show moderate chemical weathering,indicating that the sediments are chemically mature.Sedimentary redox indicative proxies,such as U/Th,V/Cr,and V/Sc,show an oxic depositional environment during sediment deposition.The intermediate CIA and other weathering index values of the St.Martin’s sediments show that the area had semiarid and humid climatic conditions throughout the deposition.The Rb/K ratio of the St.Martin’s sediments suggests that the development and deposition of the sedimentary sequence of St.Martin’s Island mainly occurred in a brackish water environment during the geological past.展开更多
The extra-peninsular Gondwana Group rocks are exposed in narrow patches within the Lesser Himalayan sequence of the NE-Arunachal Himalayas,India.The bulk of sediments for the sandstones of the Gondwana Group were deri...The extra-peninsular Gondwana Group rocks are exposed in narrow patches within the Lesser Himalayan sequence of the NE-Arunachal Himalayas,India.The bulk of sediments for the sandstones of the Gondwana Group were derived from felsic/acidic to intermediate igneous rocks,with minor mafic input from the upper continental crust(UCC),as supported by various discrimination diagrams based on quantification of detrital minerals coupled with sandstone geochemistry.The inputs from metamorphic sources in subordinate amounts cannot be ruled out,as indicated by quantification of the quartz varieties.These sediments were found to be sourced from the interior part of a craton or shield and recycled platformal sediments which were derived from both passive and active margin settings.The sediments experienced a wide variance in climatic conditions,from arid to humid,suffering low-moderate-inten-sity weathering(CIA:63.43;CIW:86.18;WIP:44.84;PIA:75.37;ICV:2.39;C-value:0.42;PF:0.49;Sr/Cu:9.23 and Rb/Sr:1.68)within the vicinity of the low plains to moderate hills.Additionally,redox-sensitive elements indicate the deposition of sediments under oxygenated or oxygen-rich conditions(U_(au):−2.91;Th/U:7.37;U/Th:0.18;V/Cr:1.71;δU:0.67 and Ce/Ce^(*):0.93).展开更多
The Central Yunnan Basin(CYB)that tectonically located on the southwest margin of the Yangtze Block and to the eastern segment of the Paleo-Tethys tectonic domain,is a typical‘red bed'sedimentary basin formed sin...The Central Yunnan Basin(CYB)that tectonically located on the southwest margin of the Yangtze Block and to the eastern segment of the Paleo-Tethys tectonic domain,is a typical‘red bed'sedimentary basin formed since Late Triassic.The CYB is composed of mega-thick fluvial and lacustrine facies successions.However,the tectonic evolution and sedimentary provenance studies on this basin are scarce.In this study,we report new detrital zircon ages of four sandstones from the Lower Jurassic Fengjiahe Formation(FJF),including four major clusters of 2060-1810,870-760,485-430,and 280-254 Ma,with sporadic Archean,Cambrian,and Triassic ages.We interpret that the Archaean and Proterozoic zircons were mainly derived from the western Yangtze Block,which may recycle from the Jiangnan Orogen,the Cathaysia Block and the Proterozoic igneous rocks.Ordovician and Silurian zircons were probably from the Ailaoshan orogenic belt,and the Lancang Group in western Yunnan,as well as the Yangtze,Cathaysia and Indosinian blocks.Permian zircons probably came from the Ailaoshan orogenic belt and the Emeishan basalt.The youngest zircon age of~212.9 Ma indicates that the depositional age of the FJF is younger than the Norian stage.We also proposed a geodynamic model of the CYB and the Ailaoshan orogenic belt during the Mesozoic.The Simao Block to the west of the CYB constituted the Ailaoshan orogenic belt and collaged with the Yangtze Block during the Early Triassic,provided sedimentary provenance to the CYB.The Changning-Menglian zone that composed of the Baoshan and the Simao Blocks,uplifted in the Late Triassic and provided provenance to the CYB.Collapse of the Ailaoshan orogenic belt in Late Triassic probably provided channel for source materials that transported from the Lincang granites to the CYB.We propose a transtensional tectonic setting of the central Yunnan during the Early Jurassic,after a short collision during the Indosinian Movement in the Late Triassic.展开更多
Based on the detrital zircon U-Pb dating data,this paper discusses the provenance and constructs source-to-sink system of the Upper Jurassic in the North Yellow Sea Basin(NYSB),eastern North China Craton(ENCC).In addi...Based on the detrital zircon U-Pb dating data,this paper discusses the provenance and constructs source-to-sink system of the Upper Jurassic in the North Yellow Sea Basin(NYSB),eastern North China Craton(ENCC).In addition,to avoid the bias of detrital zircon ages caused by variations in zircon fertility,we collected 1709 whole rock zirconium content values(ppm)from granitic rocks with different ages in the North China Craton(NCC).Based on mean Zr content of granitic rocks in each age,these granitic rocks can be divided into four groups:Group A consists of Jurassic,Group B consists of Paleozoic,Neo-Mesoproterozoic and Neoarchean,Group C consists of Early Cretaceous and Triassic,and Group D consists of Paleoproterozoic.This research assigns to these groups zircon fertility factors(ZFF)of 1,1.4,1.8 and 2.2.The U-Pb age of detrital zircons from Late Jurassic sediments corrected by ZFF is statistically analyzed(K-S test,similarity,crosscorrelation,linkeness,and multidimensional scaling).And combining with paleocurrent and paleogeography,we construct two source-to-sink systems:(1)Jiaodong uplift and Sulu Orogenic Belt as the source area and the North Yellow Sea Basin as the sink area;(2)Liaodong Peninsula as the source area and the North Yellow Sea Basin as the sink area.展开更多
The Erlian Basin is one of the most important multi-energy basins in China.The Baiyanhua area of the Chuanjing depression in the western Erlian Basin has recently become a favorable area for new progress in sandstone-...The Erlian Basin is one of the most important multi-energy basins in China.The Baiyanhua area of the Chuanjing depression in the western Erlian Basin has recently become a favorable area for new progress in sandstone-type uranium prospecting.However,the Cretaceous source-to-sink evolution of the Chuanjing depression in the Erlian Basin is poorly known.This paper presents the systematic geochemical and zircon U-Pb studies on the Saihantala Formation and Erlian Formation in the Baiyanhua area.The data obtained are functionally important for revealing the provenance and tectonic setting of the source rocks.The results show that the upper part of the Saihantala Formation and the lower part of the Erlian Formation are mainly composed of felsic sedimentary rocks.The source rocks originated from a continental margin arc environment in terms of tectonic setting.The detrital zircons ages have the dominant populations at ca.250-270 Ma,with two subdominant age groups at ca.1400-1800 and 1900-2100 Ma,respectively.Combined with the tectono-sedimentary evolution of the Chuanjing depression,we conclude that:(1)the provenance of the Cretaceous strata was mostly sourced from the Baiyanhua uplift;(2)the water depth became shallow in the Southern Sangendalai sag during the middle period of Saihantala,further preventing the formation of coal beds;(3)the formation of Baiyanhua uplift might provide the beneficial tectonic condition for uranium mineralization in the upper Saihantala Formation in southern Sangendalai sag.This is significant for us to understand the space allocation of coal and uranium in Chuanjing depression and evaluate the uranium metallogenic prospects in southern Sangendalai sag.展开更多
Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin...Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin.Some research suggests that these deposits are potentially associated with Great Flood events in the mainstream region.However,considering the multiplicity and complexity of the deposition,they may also result from catastrophic debris flows in local gullies.Consequently,we conducted a comprehensive investigation of detrital deposits and collected 64 provenance samples.The sediment provenance was analyzed by grain size distribution and elemental composition characterization.The results are as follows:(1)The detrital deposits in the basin are predominantly composed of sand and gravel,with some clay.(2)The results of the elemental ratios and multivariate statistical analysis confirmed the similarity in material composition between the detrital deposits in the basin and those from the Muduoluo Gully.(3)The discovery of palaeolandslides and lacustrine deposits in the study area indicates the existence of ancient dammed lakes and historical river damming events.The detrital deposits likely represent fan delta sediments formed by water-land interactions caused by damming events.Our study highlights new insights into discriminating the provenances of detrital deposits in localized regions,providing a new perspective for investigating geological hazards in the Jinsha River Basin.展开更多
Lunar impact glasses have been identified as crucial indicators of geochemical information regarding their source regions. Impact glasses can be categorized as either local or exotic. Those preserving geochemical sign...Lunar impact glasses have been identified as crucial indicators of geochemical information regarding their source regions. Impact glasses can be categorized as either local or exotic. Those preserving geochemical signatures matching local lithologies (e.g., mare basalts or their single minerals) or regolith bulk soil compositions are classified as “local”. Otherwise, they could be defined as “exotic”. The analysis of exotic glasses provides the opportunity to explore previously unsampled lunar areas. This study focuses on the identification of exotic glasses within the Chang’e-5 (CE-5) soil sample by analyzing the trace elements of 28 impact glasses with distinct major element compositions in comparison with the CE-5 bulk soil. However, the results indicate that 18 of the analyzed glasses exhibit trace element compositions comparable to those of the local CE-5 materials. In particular, some of them could match the local single mineral component in major and trace elements, suggesting a local origin. Therefore, it is recommended that the investigation be expanded from using major elements to including nonvolatile trace elements, with a view to enhancing our understanding on the provenance of lunar impact glasses. To achieve a more accurate identification of exotic glasses within the CE-5 soil sample, a novel classification plot of Mg# versus La is proposed. The remaining 10 glasses, which exhibit diverse trace element variations, were identified as exotic. A comparative analysis of their chemical characteristics with remote sensing data indicates that they may have originated from the Aristarchus, Mairan, Sharp, or Pythagoras craters. This study elucidates the classification and possible provenance of exotic materials within the CE-5 soil sample, thereby providing constraints for the enhanced identification of local and exotic components at the CE-5 landing site.展开更多
Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,loc...Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,located along the Minab-Zendan Fault,represents a convergence boundary between the Zagros continental domain and the Makran accretionary prism in southern Iran from the Cretaceous onwards.Several tectonic slices,including Neotethys ophiolitic remnants and the Ganj and Bajgan-Durkan complexes,have accreted along the southern margin of the Eurasian Plate during subduction in the western Makran wedge.To clarify the growth steps of the Makran Prism and the internal deformation associated with arc-continent collision,we used a provenance study of sandstones from the western Makran accretionary prism involving petrography of the main detrital components and U–Pb dating,Hf isotopic values,and trace elements of detrital zircon grains.Our findings reveal a progressive scenario in which oceanic arc-related rocks of the∼99 Ma Ganj Complex with Hf values ranging from+10 to+16 were uplifted during the Early to Late Eocene.The Eocene fore-arc sediments were sourced from the∼49–47 Ma Urumieh-Dokhtar Magmatic Arc with Hf values between−5 and+12,as well as from the Ganj Complex.The Jurassic–Cretaceous Bajgan-Durkan Complex was uplifted due to the Late Eocene to Oligocene collision of various terranes along the southern margin of the Eurasian Plate.This led to a major sediment influx into the Makran trench with a detrital signal in the range∼175–160 Ma with Hf isotopic values from−3 to+4 and alongside the Urumieh-Dokhtar Magmatic Arc with detrital ages ranging∼46–37 Ma and ca.80 Ma.Notably,metamorphic lithic grains began to appear in the sediments in the Late Eocene.The initial arrival of sediments from the Arabian margin to the arc-continent suture zone along the Minab-Zendan Fault indicates the onset of initial collision.During the Late Oligocene–Early Miocene,detrital zircon ages in the range of∼610–520 Ma,sourced from the Arabian basement,were deposited in the trench basin together with components from the Eocene Urumieh-Dokhtar Magmatic Arc and Cretaceous ophiolitic clasts of∼93 Ma with Hf isotopic values of+12 to+16.Following the development and uplift of the orogen from the Middle Miocene onward,detrital zircon grains from the Cretaceous–Miocene Urumieh-Dokhtar Magmatic Arc,Jurassic–Cretaceous Bajgan-Durkan Complex,and Cretaceous ophiolites are present in both the Makran and Zagros sedimentary domains.展开更多
An enhanced understanding of the history of the western Qinling-Dabie orogen is pivotal in reconstructing geological processes of the east Asian mainland.However,less attention has been paid to its early-stage uplift-...An enhanced understanding of the history of the western Qinling-Dabie orogen is pivotal in reconstructing geological processes of the east Asian mainland.However,less attention has been paid to its early-stage uplift-erosion history after closure of surrounding oceanic basins at the mid-Paleozoic.In this study,we undertook a comprehensive study including paleocurrent reconstruction,sandstone petrology,and detrital zircon U-Pb dating on Late Carboniferous to Early Permian successions in the southern Ordos neighboring the northern Qinling-Dabie.New provenance data reveal a significant provenance shift at the Carboniferous-Permian transition.The older Benxi Formation was sourced southerly from the North Qinling Terrane that provided detritus mostly of Neoproterozoic and Early Paleozoic ages.In contrast,Early Permian samples yield age relation dominated by Neoarchean,Paleoproterozoic,Early Paleozoic,and Late Paleozoic age populations,with a significant gap of ca.1600-550 Ma,implying a sediment derivation from the Inner Mongolia Continental Arc.This shift is further verified by paleocurrent transition from south to north then.We suggest that the North Qinling Terrane experienced a significant uplift history from ca.500 Ma and remained as a highland until end-Carboniferous.From Early Permian,the North Qinling Terrane was submerged,covered by widespread deltaic sedimentation there.Northerly source from the Inner Mongolia Continental Arc began to be accumulated in the northern flank of the North Qinling Terrane,before termination approximately along the southern North Qinling Terrane,where shallow-water carbonate shelf sedimentation sustained from Devonian to Triassic.This new finding indicates that uplift of the North Qinling Terrane lasted about 150 Ma after the Proto-Tethys Ocean closure.展开更多
The Qinling orogenic belt in central China underwent long-term tectonic evolution during an amalgamation between the North China and South China cratons.However,intense compressional deformation and uplift erosion res...The Qinling orogenic belt in central China underwent long-term tectonic evolution during an amalgamation between the North China and South China cratons.However,intense compressional deformation and uplift erosion resulted in the transformation and disappearance of much geological record from the Qinling orogenic belt,and the tectonic evolution of this belt remains poorly constrained during the Triassic.Located in the northernmost margin of the South China Craton,the Sichuan Basin preserves the complete Triassic sedimentary succession,and can provide significant information for understanding the Triassic tectonic evolution of the Qinling orogenic belt.We present detrital zircon U-Pb dating,trace element and in situ Lu-Hf isotope data for the Middle Triassic Leikoupo Formation and the Late Triassic Xujiahe Formation samples from the eastern Sichuan Basin,South China.The detrital zircon U-Pb ages of the Leikoupo Formation show seven age clusters of 280-242,350-300,500-400,1000-800,2000-1750,2100-2000 and 2600-2400 Ma,while those of the Xujiahe Formation show five age clusters of 300-200,500-350,1050-950,2000-1750 and 2600-2400 Ma.Combined with published paleocurrent and paleogeographic data,the sediments of the Leikoupo Formation are interpreted to be sourced from the North China Craton,Yangtze Craton and North Qinling orogenic belt,and the potential main source regions of the Xujiahe Formation included the South and North Qinling orogenic belts.Provenance analysis indicates that the North Qinling orogenic belt was in inherited uplift and coeval denudation in the Middle Triassic.The proportion of the detritus formed in the South Qinling orogenic belt increases gradually from the Leikoupo to Xujiahe formations.This significant provenance change indicates that rapid tectonic uplift and extensive denudation of the South Qinling orogenic belt occurred in the early Late Triassic,which is related to the collision between the North China and South China cratons during the Triassic.展开更多
The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study cruci...The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study crucial for understanding environmental changes in the region.Despite its importance,research on the Shichuanhe River basin has thus far been primarily focused on riverbank construction,with limited exploration of its sediment characteristics.Although river sediments hold potential for guiding agricultural practices in the area,comprehensive studies on their composition and provenance remain scarce.To address this gap,a systematic sediment sampling campaign was conducted in the lower reaches of the Shichuanhe River,and detailed mineralogical analyses were performed.The results show that the sediment is predominantly composed of detrital quartz and feldspar(albite and orthoclase),with heavy minerals constituting approximately 10%–12%of the total sediment volume.The analysis of the heavy mineral assemblage reveals an absence of signifi cant contributions from igneous rocks in the sedimentary profi le.Furthermore,the distribution patterns of major,trace,and rare-earth elements in the Shichuanhe River’s argillaceous sediments exhibit similarities to those found in the Weihe River’s sediments.Elemental fractionation patterns suggest that the Shichuanhe River sediments are primarily derived from Loess Plateau sediments,aligning with fi ndings from both the Weihe River and the middle reaches of the Yellow River.展开更多
The radial sand ridge system （RSRS） located at Jiangsu coast of China attracts much attention on its origin and mechanic of formation for its special structure and potential land resource. Due to complicated hydrody...The radial sand ridge system （RSRS） located at Jiangsu coast of China attracts much attention on its origin and mechanic of formation for its special structure and potential land resource. Due to complicated hydrodynamic condition, the Jiangsu RSRS is a hot debated on its potential sources, Yangtze River or Yellow River？ We collected ten sand samples from surface sediments along the west coast of Bohai Sea and Yellow Sea from the modern Yellow River estuary to Yangtze River estuary in summer, 2013. The samples are analyzed by method of detrital zircon age for source identification of the RSRS sediments. The U-Pb age spectra of detrital zircon grains of the samples show a wide range from Cenozoic to Late Archean with several age peaks. Comparing the age spectra between the Yangtze River and the Yellow River, the detrital zircons have younger age （〈100 Ma） group in the Yangtze River. These age distribution of the Jiangsu coastal RSRS sediments are similar to that of the Yangtze River, but different from the Yellow River. The samples located adjacent to the old Yellow River Delta show more wide-range age distribution, implying a compounded origination from the both rivers. Based on these findings it is proposed that, contrary to common opinion, the main sediment source of the Jiangsu RSRS is the Yangtze River, rather than the Yellow River. By implication, there should be evidence of hydrodynamic mechanics of oceanic currents and tidal motion. This aspect awaits confirmation in future research.展开更多
We present major and trace and Nd-isotopic data of the^1.67 Ga Buanji Group of southwestern Tanzania in order to constrain the nature of their protolith and the intensity of chemical weathering in the source terranes ...We present major and trace and Nd-isotopic data of the^1.67 Ga Buanji Group of southwestern Tanzania in order to constrain the nature of their protolith and the intensity of chemical weathering in the source terranes and make inferences on the nature of climatic conditions during the late Paleoproterozoic in the region. Major and trace element contents of the shales from three stratigraphic formations are comparable to those of the post-Archaean Australian Shale(PAAS) and the average Proterozoic Shale(PS). They are characterized by enrichments in LREE relative to HREE((La/Yb)_(CN)=9.07-13.2;(Gd/Yb)cN = 1.51-1.85) and negative Eu anomalies(Eu/Eu~* = 0.61-0.81); features which are comparable to those of PAAS and PS, indicating upper continental sources. Provenance proxy ratios,together with abundances of Cr, Ni, Co and V that increase up-stratigraphy suggest a decreasing input of felsic detritus up-stratigraphy. Chemical Indices of Alteration(CIA) for the lower, middle and upper Buanji formations are 81. 76 and 79, respectively. These indices largely indicate intermediate(ca. 60-80)to extreme(>80) weathering intensities of the precursor rocks. These observations may suggest the prevalence of warm, humid climates during the late Paleoproterozoic in the region.The lower Buanji Formation yielded a depleted mantle Nd model age(T_(DM)) of 、2100 Ma which indicates an Eburnean parentage. T_(DM) ages of 2486-2155 Ma and 2535-2379 Ma obtained from middle and upper Buanji formations, respectively, suggest a progressive increase of sedimentary input from the Tanzania Craton up-stratigraphy. The Eburnean T_(DM) ages of the lower Buanji rocks are attributed to their derivation through denudation of a decaying topographic high composed predominantly of rocks that were generated during the Palaeoproterozoic Ubendian orogenesis, possibly in the realm of Columbian Supercontinent assembly. Overlapping T_(DM) ages between the middle and upper Buanji formations suggest multiple sources involving mixing of detritus from Archaean cratonic rocks and the Palaeoproterozoic Ubendian belt. However, the Archaean signal is relatively more pronounced in the upper Buanji Formation, suggesting sediments derivation from the craton, to the north of the basin. The middle Buanji Formation suggests more diverse protolith,given the relatively larger spread in the T_(DM) ages. The Nb/Ta, Zr/Sm and Ce/Pb ratios coupled with the negative Nb and Ta anomalies, relative to primitive mantle, suggest that the tectonic setting of the source rocks for the Buanji sediments was a subduction zone akin to that generating modern sland Arc Basalts. Thus, we suggest that the Buanji's palaeogeography is consistent with an extensional continental backarc basin during the late Paleoproterozoic.展开更多
During the Late Carboniferous to Early Permian,a rift was formed by post-collisional extension after ocean closure or an island arc-related basin formed by Paleo-Asian Ocean(PAO)subduction in the Xi Ujimqin area.Never...During the Late Carboniferous to Early Permian,a rift was formed by post-collisional extension after ocean closure or an island arc-related basin formed by Paleo-Asian Ocean(PAO)subduction in the Xi Ujimqin area.Nevertheless,the closure time of the PAO is still under debate.Thus,to identify the origin of the PAO,the geochemistry and U-Pb age of zircons were analyzed for the extra-large deep marine,polymict clastic boulders and sandstones in the Shoushangou Formation within the basin.The analyses revealed magmatic activity and tectonic evolution.The conglomerates include megaclasts of granite(298.8±9.1 Ma)and granodiorite porphyry(297.1±3.1 Ma),which were deposited by muddy debris flow.Results of this study demonstrated that the boulders of granitoids have the geochemistry of typical I-type granite,characterized by low Zr+Nb+Ce+Y and low Ga/Al values.The granitoid boulders were formed in island arc setting,indicating the presence of arc magmatism in the area that is composed of the Late Carboniferous to Early Permian subduction-related granitoid in southern Xi Ujimqin.Multiple diagrams for determining sedimentary provenance using major and trace elements indicate that Shoushangou sediments originated from continental island arc-related felsic rocks.Detrital zircon U-Pb age cluster of 330–280 Ma was obtained,indicating input from granite,ophiolite,Xilin Gol complex,and Carboniferous sources to the south.The basin was geographically developed behind the arc during the Early Permian period because the outcropped intrusive rocks in the Late Carboniferous to Early Permian form a volcanic arc.The comprehensive analyses of source areas suggest that Shoushangou sediments developed in a backarc basin in response to the northward subduction of the PAO.The backarc basin and intrusive rocks,in addition to previously published Late Carboniferous to Early Permian magmatic rocks of arc unit in Xilin Gol,confirm the presence of an Early Permian trencharc-basin system in the region,represented by the Baolidao arc and Xi Ujimqin backarc basin.This study highlights the importance and potential of combined geochemical and geochronological studies of conglomerates and sandstone for reconstructing the geodynamic setting of a basin.展开更多
Six outcrop sections in Fenghe River,Northwestern China,were sampled and analyzed.This study aims to determine provenance,tectonic setting,and source-area paleoweathering of the sediments of Fenghe River in combinatio...Six outcrop sections in Fenghe River,Northwestern China,were sampled and analyzed.This study aims to determine provenance,tectonic setting,and source-area paleoweathering of the sediments of Fenghe River in combination of lithofacies analysis and bulk-rock geochemical data.The lithofacies in the studied area were classified as gravel,sand,and fine-grained clastic lithofacies,reflecting generally channel fill deposits,channel bar deposits,and over-bank deposits,respectively.The Chemical Index of Alteration(CIA),Plagioclase Index of Alteration(PIA),and Chemical Index of Weathering(CIW)values ranged 50.10–62.29,50.13–66.35,56.52–71.12,respectively,together with element ratios such as Rb/Sr,K/Na,Rb/K,Th/K,Rb/Ti,and Cs/Ti indicate that the source area was under a low to moderate chemical weathering condition probably in cold and semi-arid climates.Moreover,plot of SiO_(2)vs.(Al_(2)O_(3)+K_(2)O+Na_(2)O)suggests that the sediments were deposited in a semi-arid climate.Plots of Cr/Th vs.Th/Sc,TiO_(2)vs.Zr,La/Yb vs.rare earth element(REE),and La-Th-Sc ternary diagrams,along with the lithology,indicate that the sediments in Fenghe River were mainly originated from felsic igneous rocks.Major elements-based discrimination diagrams and Th-Sc-Zr/10 and La-Th-Sc ternary diagram of the samples indicates that the source rocks of Fenghe River developed in a composite active continental margin and continental island arc field.展开更多
The Aghajari Formation, called also the Upper Fars, develops throughout the Folded Zagros Zone and its thickness in the type section in southwest of Iran is 2966 meters. To analyze the sedimentary basin of this Format...The Aghajari Formation, called also the Upper Fars, develops throughout the Folded Zagros Zone and its thickness in the type section in southwest of Iran is 2966 meters. To analyze the sedimentary basin of this Formation, lithofacies, architectural elements and petrofacies of the related deposits in a section in southeast of Sarvestan in Fars Province of Iran with a thickness of 2221.45 meters were examined. Microscopically studying thin sections, the petrography and the occurrence of the deposits were determined. In this section, 16 lithofacies, 10 architectural elements and 2 sandstone petrofacies were identified. The lithofacies were divided into two major and minor groups, in which the major lithofacies consist of coarse-grained （Gh, Gp, Gt and Gm）, medium-grained （Sh, Sp, St, Sl, Sm, Sr and Ss and fine-grained ones （Fm, Fl and Fsm）, and the minor lithofacies were evaporative and mixed silisiclastic-carbonate. The identified architectural elements are CH, SB, GB, LA, DA, CR, CS, LV, LS, CH （FF） and FF. By combining evidences from facies analysis and architectural elements together, the Aghajari Formation was divided into three parts in which the related sedimentation environments, from top to bottom, are gravel, gravel-sand and fine-grained meandering river respectively. There have also been playas and shoreface in the lower part. Based on petrography, the sandstones of this formation were classified into two groups： litharenite and sublitharenite. The origin of these deposits （sandstones） was appointed to the recycled orogeny and the source of quartz is low and medium to high metamorphic rank. Using the field evidences, the paleocurrent direction was achieved indicating the direction of the paleocurrent from northwest to southeast at the time of deposition. It is hoped that these data can be used in the interpretation of the basin and reconstruction of the paleogeography in the local and regional scales.展开更多
The characteristics of sedimentary petrology are significant in determining geological provenance. By using field outcrop observation and indoor identification of thin sections, the characteristics of Jurassic system ...The characteristics of sedimentary petrology are significant in determining geological provenance. By using field outcrop observation and indoor identification of thin sections, the characteristics of Jurassic system Tuchengzi Formation clastic rocks exposed in the Beijing Yanqing “flowerpot” basin, which include rock types, clastic composition and cement type, etc. have been analyzed systematically to identify the provenance direction and tectonic setting and nature of the provenance. Research shows that the sedimentary rocks in this area belong to analluvial fan and braided river sedimentary rock system and include mainly conglomerates, lithic sandstone, and feldspathic lithic sandstone. The main compositions of the conglomerate are dolomite and limestone. Nearly 50% to 70% of the sandstones are mainly polycrystalline quartz;10% to 15% are feldspar;and 40% to 55% are composed of debris from mainly magmatic and metamorphic rocks. A Dickinson triangular diagram indicates that the provenance type in this area is recycled orogny evolving from clastic recycled orogeny such as a collisional orogenic belt to a transitional recycled orogeny. On the basis of the geographic position and tectonic setting, three types of provenance can be identified in the Jurassic system Tuchengzi Formation. The far source provenances are Archean erathem basement metamorphic rocks in the northern basin and granite or adamellite that intruded rocks of the Late Jurassic epoch of the Yanshanian period in the northeast. The nearby provenance is the Mesoproterozoic erathem Changchengian system and Jixianianian system dolomite in both the east and west.展开更多
The petrographic and geochemical attributes of the Oligocene Barail Group of rocks are used to decipher the likely source area(s)or tectonic domains,as this sequence of rocks was deposited in a foreland basin governed...The petrographic and geochemical attributes of the Oligocene Barail Group of rocks are used to decipher the likely source area(s)or tectonic domains,as this sequence of rocks was deposited in a foreland basin governed by orogenic domain,namely the North-east Arunachal Himalayas.The river system that gave rise to the Brahmaputra River(Yarlung-Tsangpo),which flowed through several tectonic domains of the Himalayan ranges,primarily from BomiChayu,Gangadese Granitoid,Higher Himalayan Leucogranites,and Namche Barwa into the proto Bengal Basin now a part of Assam Arakan Basin and Naga Schuppen Belt,was the main source of the sandstone formation of the Barail Group.The purpose of sandstone petrography,which combines modal analysis with XRF(Major Oxides)and HR-ICPMS(Trace&Rare Earth Elements)research,is to identify the type of source rock(s),their weathering pattern,and its paleo-environmental circumstances.These sandstones were formed from recycled orogen and include lithic and sublithic arenite variants with advanced texture and chemical maturity.The sediments were felsic(Th/Co:1.38,Cr/Th:9.78,La/Lu:11.58,Th/Sc:0.99,Eu/Eu*:0.66,La/Sc:3.05,La/Co:4.18),with contributions from intermediate source rocks and low-rank metamorphics deposited in an active continental margin to a continental island arc setting.Climatic conditions impacted the sediments of Barails,characterised by being warm and semi-humid to humid which resulted in moderate to a high degree of chemical weathering,as shown by weathering indices like CIA(79.14),PIA(85.47),CIW(86.9),WIP(32.50),ICV(0.71),and Th/U(6.03),which were further additionally supported by C-Value(1.01),PF(1.20),Sr/Cu(2.04),and Rb/Sr(0.97).展开更多
基金Projects 40872077 supported by the National Natural Science Foundation of China2008CDA098 by the Key Natural Science Foundation of Hubei Province
文摘Reconstructed synsedimentary paleogeomorpholgy is an effective method in predicting the distribution of sandbodies and can provide valid evidence in the search for reservoirs. Based on a synsedimentary paleogeomorpholgy reconstruction of the third member of the Dongying formation (Ed3) in the Qikou sag,the basic paleogeomorphic characteristics of Ed3 are described and the spatial distributions of denudation and subsidence areas are discussed. Key boundary faults controlling the deposition of important sediment bodies are proposed and the interrelations among faulted slope-break belts or flexure belts,intra-depression uplifts and sags,sediment sources and sediments input points have been investigated.
基金supported by the National Basic Research Program of China(NO.2009CB219306)the New Century Excellent Talent Program of Ministry of Education of China(NCET-04-0345)
文摘Huhehu Sag is a new battlefield for the future oil and gas exploration in the Hailar Basin. At present, exploration of this area stays at a low level and the understanding of the provenance system of the Nantun Formation is comparatively weak. So, to carry out the detailed depiction of the provenance system in the study area is significant for the sedimentary system reconstruction, for the prediction of reservoir distribution and favorable areas. Based on comprehensive analysis of paleogeomorphy, light-heavy mineral and seismic reflection features, sandstone thickness and sandstone percentage, this paper analyzes in detail the provenance system of the Nantun Formation in Huhehu Sag from various angles and levels. It shows that provenances of the Huhehu Sag mainly originated from the eastern Xilinbeier Salient and western Bayan Mountain Uplift. The provenances surrounding the lake basin converged to the center of the basin, among which, the steep slope belt and the gentle slope belt are the main provenances, and the southern uplift is a secondary one. The distribution framework of the provenance fundamentally determines the distribution rules of the depositional system and its sand body developing during the Nantun period.
基金Supporting Program for funding this work under Project number(RSP2024R328),King Saud University,Riyadh,Saudi Arabia.
文摘The sedimentary geochemistry of St.Martin’s Island is important to determine the origin of the source rock,paleo weathering,tectonic setting,sediment recycling,maturity,sorting,redox condition,and paleo salinity of the sediments.Major oxides,trace elements,and rare earth elements(REEs)obtained from the INAA technique are presented by analyzing the sediment samples collected from the shoreline of St.Martin’s Island,Bangladesh.The elemental ratios,comparison with average upper continental crust(UCC),binary diagrams(Th/Sc vs.Sc,La/Th vs.Hf,Th/Co vs.La/Sc),and chondrite normalized REE patterns exhibit substantial LREE enrichment,relatively fl at HREE fractionation,considerable negative Eu anomalies(average:0.72),indicates the derivation from a source dominated by felsic rock,with contribution from intermediate source and mafi c component.Sediments from St.Martin’s Island exhibit the deposition of sediments in transitional environments of active and passive continental margin settings.Weathering indices value of CIA,PIA,CIW,CIX,and K 2 O/Rb ratio show moderate chemical weathering,indicating that the sediments are chemically mature.Sedimentary redox indicative proxies,such as U/Th,V/Cr,and V/Sc,show an oxic depositional environment during sediment deposition.The intermediate CIA and other weathering index values of the St.Martin’s sediments show that the area had semiarid and humid climatic conditions throughout the deposition.The Rb/K ratio of the St.Martin’s sediments suggests that the development and deposition of the sedimentary sequence of St.Martin’s Island mainly occurred in a brackish water environment during the geological past.
文摘The extra-peninsular Gondwana Group rocks are exposed in narrow patches within the Lesser Himalayan sequence of the NE-Arunachal Himalayas,India.The bulk of sediments for the sandstones of the Gondwana Group were derived from felsic/acidic to intermediate igneous rocks,with minor mafic input from the upper continental crust(UCC),as supported by various discrimination diagrams based on quantification of detrital minerals coupled with sandstone geochemistry.The inputs from metamorphic sources in subordinate amounts cannot be ruled out,as indicated by quantification of the quartz varieties.These sediments were found to be sourced from the interior part of a craton or shield and recycled platformal sediments which were derived from both passive and active margin settings.The sediments experienced a wide variance in climatic conditions,from arid to humid,suffering low-moderate-inten-sity weathering(CIA:63.43;CIW:86.18;WIP:44.84;PIA:75.37;ICV:2.39;C-value:0.42;PF:0.49;Sr/Cu:9.23 and Rb/Sr:1.68)within the vicinity of the low plains to moderate hills.Additionally,redox-sensitive elements indicate the deposition of sediments under oxygenated or oxygen-rich conditions(U_(au):−2.91;Th/U:7.37;U/Th:0.18;V/Cr:1.71;δU:0.67 and Ce/Ce^(*):0.93).
基金supported by the Open Foundation of the State Key Laboratory of Continental Dynamics,Northwest University,China(No.16LCD06)the Basic Research Program from Department of Science and Technology Yunnan Province(No.202101AU070132)+1 种基金Jun Wang was also supported by the‘Double Top’Construction Projects(No.C176220100135)at Yunnan Universitysupported by the open fund from the Key Laboratory of Deep-Earth Dynamics of the Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing,10037,China(No.J1901)。
文摘The Central Yunnan Basin(CYB)that tectonically located on the southwest margin of the Yangtze Block and to the eastern segment of the Paleo-Tethys tectonic domain,is a typical‘red bed'sedimentary basin formed since Late Triassic.The CYB is composed of mega-thick fluvial and lacustrine facies successions.However,the tectonic evolution and sedimentary provenance studies on this basin are scarce.In this study,we report new detrital zircon ages of four sandstones from the Lower Jurassic Fengjiahe Formation(FJF),including four major clusters of 2060-1810,870-760,485-430,and 280-254 Ma,with sporadic Archean,Cambrian,and Triassic ages.We interpret that the Archaean and Proterozoic zircons were mainly derived from the western Yangtze Block,which may recycle from the Jiangnan Orogen,the Cathaysia Block and the Proterozoic igneous rocks.Ordovician and Silurian zircons were probably from the Ailaoshan orogenic belt,and the Lancang Group in western Yunnan,as well as the Yangtze,Cathaysia and Indosinian blocks.Permian zircons probably came from the Ailaoshan orogenic belt and the Emeishan basalt.The youngest zircon age of~212.9 Ma indicates that the depositional age of the FJF is younger than the Norian stage.We also proposed a geodynamic model of the CYB and the Ailaoshan orogenic belt during the Mesozoic.The Simao Block to the west of the CYB constituted the Ailaoshan orogenic belt and collaged with the Yangtze Block during the Early Triassic,provided sedimentary provenance to the CYB.The Changning-Menglian zone that composed of the Baoshan and the Simao Blocks,uplifted in the Late Triassic and provided provenance to the CYB.Collapse of the Ailaoshan orogenic belt in Late Triassic probably provided channel for source materials that transported from the Lincang granites to the CYB.We propose a transtensional tectonic setting of the central Yunnan during the Early Jurassic,after a short collision during the Indosinian Movement in the Late Triassic.
基金supported by the National Natural Science Foundation of China(Nos.41872101 and 41790453-4)。
文摘Based on the detrital zircon U-Pb dating data,this paper discusses the provenance and constructs source-to-sink system of the Upper Jurassic in the North Yellow Sea Basin(NYSB),eastern North China Craton(ENCC).In addition,to avoid the bias of detrital zircon ages caused by variations in zircon fertility,we collected 1709 whole rock zirconium content values(ppm)from granitic rocks with different ages in the North China Craton(NCC).Based on mean Zr content of granitic rocks in each age,these granitic rocks can be divided into four groups:Group A consists of Jurassic,Group B consists of Paleozoic,Neo-Mesoproterozoic and Neoarchean,Group C consists of Early Cretaceous and Triassic,and Group D consists of Paleoproterozoic.This research assigns to these groups zircon fertility factors(ZFF)of 1,1.4,1.8 and 2.2.The U-Pb age of detrital zircons from Late Jurassic sediments corrected by ZFF is statistically analyzed(K-S test,similarity,crosscorrelation,linkeness,and multidimensional scaling).And combining with paleocurrent and paleogeography,we construct two source-to-sink systems:(1)Jiaodong uplift and Sulu Orogenic Belt as the source area and the North Yellow Sea Basin as the sink area;(2)Liaodong Peninsula as the source area and the North Yellow Sea Basin as the sink area.
基金funded by the project initiated by the China Geological Survey“Investigation of sandstone-type uranium deposits in the Ordos and Qaidam Basins”(No.DD20190119)the National Key Research and Development Project(No.2018YFC0604200)from the Ministry of Science and Technology of the International Geoscience Programme(No.IGCP675),which is a joint endeavor of UNESCO and IUGS。
文摘The Erlian Basin is one of the most important multi-energy basins in China.The Baiyanhua area of the Chuanjing depression in the western Erlian Basin has recently become a favorable area for new progress in sandstone-type uranium prospecting.However,the Cretaceous source-to-sink evolution of the Chuanjing depression in the Erlian Basin is poorly known.This paper presents the systematic geochemical and zircon U-Pb studies on the Saihantala Formation and Erlian Formation in the Baiyanhua area.The data obtained are functionally important for revealing the provenance and tectonic setting of the source rocks.The results show that the upper part of the Saihantala Formation and the lower part of the Erlian Formation are mainly composed of felsic sedimentary rocks.The source rocks originated from a continental margin arc environment in terms of tectonic setting.The detrital zircons ages have the dominant populations at ca.250-270 Ma,with two subdominant age groups at ca.1400-1800 and 1900-2100 Ma,respectively.Combined with the tectono-sedimentary evolution of the Chuanjing depression,we conclude that:(1)the provenance of the Cretaceous strata was mostly sourced from the Baiyanhua uplift;(2)the water depth became shallow in the Southern Sangendalai sag during the middle period of Saihantala,further preventing the formation of coal beds;(3)the formation of Baiyanhua uplift might provide the beneficial tectonic condition for uranium mineralization in the upper Saihantala Formation in southern Sangendalai sag.This is significant for us to understand the space allocation of coal and uranium in Chuanjing depression and evaluate the uranium metallogenic prospects in southern Sangendalai sag.
基金The National Key R&D Program of China,No.2023YFC3008300The Second Tibetan Plateau Scientific Expedition and Research(STEP),No.2019QZKK0903+1 种基金The Science and Technology Research Program of Institute of Mountain Hazards and Environment,CAS,No.IMHE-ZDRW-03National Natural Science Foundation of China,No.42071017。
文摘Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin.Some research suggests that these deposits are potentially associated with Great Flood events in the mainstream region.However,considering the multiplicity and complexity of the deposition,they may also result from catastrophic debris flows in local gullies.Consequently,we conducted a comprehensive investigation of detrital deposits and collected 64 provenance samples.The sediment provenance was analyzed by grain size distribution and elemental composition characterization.The results are as follows:(1)The detrital deposits in the basin are predominantly composed of sand and gravel,with some clay.(2)The results of the elemental ratios and multivariate statistical analysis confirmed the similarity in material composition between the detrital deposits in the basin and those from the Muduoluo Gully.(3)The discovery of palaeolandslides and lacustrine deposits in the study area indicates the existence of ancient dammed lakes and historical river damming events.The detrital deposits likely represent fan delta sediments formed by water-land interactions caused by damming events.Our study highlights new insights into discriminating the provenances of detrital deposits in localized regions,providing a new perspective for investigating geological hazards in the Jinsha River Basin.
基金funded by the National Natural Science Foundation of China (Grant Nos. 42241103 and 62227901)the Key Research Program of the Institute of Geology and Geophysics, Chinese Academy of Sciences (Grant Nos. IGGCAS-202101 and IGGCAS-202401)
文摘Lunar impact glasses have been identified as crucial indicators of geochemical information regarding their source regions. Impact glasses can be categorized as either local or exotic. Those preserving geochemical signatures matching local lithologies (e.g., mare basalts or their single minerals) or regolith bulk soil compositions are classified as “local”. Otherwise, they could be defined as “exotic”. The analysis of exotic glasses provides the opportunity to explore previously unsampled lunar areas. This study focuses on the identification of exotic glasses within the Chang’e-5 (CE-5) soil sample by analyzing the trace elements of 28 impact glasses with distinct major element compositions in comparison with the CE-5 bulk soil. However, the results indicate that 18 of the analyzed glasses exhibit trace element compositions comparable to those of the local CE-5 materials. In particular, some of them could match the local single mineral component in major and trace elements, suggesting a local origin. Therefore, it is recommended that the investigation be expanded from using major elements to including nonvolatile trace elements, with a view to enhancing our understanding on the provenance of lunar impact glasses. To achieve a more accurate identification of exotic glasses within the CE-5 soil sample, a novel classification plot of Mg# versus La is proposed. The remaining 10 glasses, which exhibit diverse trace element variations, were identified as exotic. A comparative analysis of their chemical characteristics with remote sensing data indicates that they may have originated from the Aristarchus, Mairan, Sharp, or Pythagoras craters. This study elucidates the classification and possible provenance of exotic materials within the CE-5 soil sample, thereby providing constraints for the enhanced identification of local and exotic components at the CE-5 landing site.
基金This research was supported by the NSFC grant(No.92255303)The first author is grateful for support from the IGGCAS postdoctoral program(2016IFPR01)under the guidance of Prof.Bo Wan.
文摘Arc-continent collision zones are critical areas where uplift,accretion,and erosion processes significantly influence the growth,elimination,or recycling of the continental crust.The Zagros–Makran Transition Zone,located along the Minab-Zendan Fault,represents a convergence boundary between the Zagros continental domain and the Makran accretionary prism in southern Iran from the Cretaceous onwards.Several tectonic slices,including Neotethys ophiolitic remnants and the Ganj and Bajgan-Durkan complexes,have accreted along the southern margin of the Eurasian Plate during subduction in the western Makran wedge.To clarify the growth steps of the Makran Prism and the internal deformation associated with arc-continent collision,we used a provenance study of sandstones from the western Makran accretionary prism involving petrography of the main detrital components and U–Pb dating,Hf isotopic values,and trace elements of detrital zircon grains.Our findings reveal a progressive scenario in which oceanic arc-related rocks of the∼99 Ma Ganj Complex with Hf values ranging from+10 to+16 were uplifted during the Early to Late Eocene.The Eocene fore-arc sediments were sourced from the∼49–47 Ma Urumieh-Dokhtar Magmatic Arc with Hf values between−5 and+12,as well as from the Ganj Complex.The Jurassic–Cretaceous Bajgan-Durkan Complex was uplifted due to the Late Eocene to Oligocene collision of various terranes along the southern margin of the Eurasian Plate.This led to a major sediment influx into the Makran trench with a detrital signal in the range∼175–160 Ma with Hf isotopic values from−3 to+4 and alongside the Urumieh-Dokhtar Magmatic Arc with detrital ages ranging∼46–37 Ma and ca.80 Ma.Notably,metamorphic lithic grains began to appear in the sediments in the Late Eocene.The initial arrival of sediments from the Arabian margin to the arc-continent suture zone along the Minab-Zendan Fault indicates the onset of initial collision.During the Late Oligocene–Early Miocene,detrital zircon ages in the range of∼610–520 Ma,sourced from the Arabian basement,were deposited in the trench basin together with components from the Eocene Urumieh-Dokhtar Magmatic Arc and Cretaceous ophiolitic clasts of∼93 Ma with Hf isotopic values of+12 to+16.Following the development and uplift of the orogen from the Middle Miocene onward,detrital zircon grains from the Cretaceous–Miocene Urumieh-Dokhtar Magmatic Arc,Jurassic–Cretaceous Bajgan-Durkan Complex,and Cretaceous ophiolites are present in both the Makran and Zagros sedimentary domains.
基金the National Natural Science Foundation of China(Grant Nos:42372253 and 42072260)the Youth Innovation Team of Shaanxi Universitiesthe Science and Technology Project of PetroChina(No.2023ZZ0201).
文摘An enhanced understanding of the history of the western Qinling-Dabie orogen is pivotal in reconstructing geological processes of the east Asian mainland.However,less attention has been paid to its early-stage uplift-erosion history after closure of surrounding oceanic basins at the mid-Paleozoic.In this study,we undertook a comprehensive study including paleocurrent reconstruction,sandstone petrology,and detrital zircon U-Pb dating on Late Carboniferous to Early Permian successions in the southern Ordos neighboring the northern Qinling-Dabie.New provenance data reveal a significant provenance shift at the Carboniferous-Permian transition.The older Benxi Formation was sourced southerly from the North Qinling Terrane that provided detritus mostly of Neoproterozoic and Early Paleozoic ages.In contrast,Early Permian samples yield age relation dominated by Neoarchean,Paleoproterozoic,Early Paleozoic,and Late Paleozoic age populations,with a significant gap of ca.1600-550 Ma,implying a sediment derivation from the Inner Mongolia Continental Arc.This shift is further verified by paleocurrent transition from south to north then.We suggest that the North Qinling Terrane experienced a significant uplift history from ca.500 Ma and remained as a highland until end-Carboniferous.From Early Permian,the North Qinling Terrane was submerged,covered by widespread deltaic sedimentation there.Northerly source from the Inner Mongolia Continental Arc began to be accumulated in the northern flank of the North Qinling Terrane,before termination approximately along the southern North Qinling Terrane,where shallow-water carbonate shelf sedimentation sustained from Devonian to Triassic.This new finding indicates that uplift of the North Qinling Terrane lasted about 150 Ma after the Proto-Tethys Ocean closure.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC0602704)the National Natural Science Foundation of China(Grant No.U20B6001 and 91755211).
文摘The Qinling orogenic belt in central China underwent long-term tectonic evolution during an amalgamation between the North China and South China cratons.However,intense compressional deformation and uplift erosion resulted in the transformation and disappearance of much geological record from the Qinling orogenic belt,and the tectonic evolution of this belt remains poorly constrained during the Triassic.Located in the northernmost margin of the South China Craton,the Sichuan Basin preserves the complete Triassic sedimentary succession,and can provide significant information for understanding the Triassic tectonic evolution of the Qinling orogenic belt.We present detrital zircon U-Pb dating,trace element and in situ Lu-Hf isotope data for the Middle Triassic Leikoupo Formation and the Late Triassic Xujiahe Formation samples from the eastern Sichuan Basin,South China.The detrital zircon U-Pb ages of the Leikoupo Formation show seven age clusters of 280-242,350-300,500-400,1000-800,2000-1750,2100-2000 and 2600-2400 Ma,while those of the Xujiahe Formation show five age clusters of 300-200,500-350,1050-950,2000-1750 and 2600-2400 Ma.Combined with published paleocurrent and paleogeographic data,the sediments of the Leikoupo Formation are interpreted to be sourced from the North China Craton,Yangtze Craton and North Qinling orogenic belt,and the potential main source regions of the Xujiahe Formation included the South and North Qinling orogenic belts.Provenance analysis indicates that the North Qinling orogenic belt was in inherited uplift and coeval denudation in the Middle Triassic.The proportion of the detritus formed in the South Qinling orogenic belt increases gradually from the Leikoupo to Xujiahe formations.This significant provenance change indicates that rapid tectonic uplift and extensive denudation of the South Qinling orogenic belt occurred in the early Late Triassic,which is related to the collision between the North China and South China cratons during the Triassic.
基金supported by the Key Project of Natural Science Basic Research Program of Shaanxi Province(2023-JC-ZD-16).
文摘The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study crucial for understanding environmental changes in the region.Despite its importance,research on the Shichuanhe River basin has thus far been primarily focused on riverbank construction,with limited exploration of its sediment characteristics.Although river sediments hold potential for guiding agricultural practices in the area,comprehensive studies on their composition and provenance remain scarce.To address this gap,a systematic sediment sampling campaign was conducted in the lower reaches of the Shichuanhe River,and detailed mineralogical analyses were performed.The results show that the sediment is predominantly composed of detrital quartz and feldspar(albite and orthoclase),with heavy minerals constituting approximately 10%–12%of the total sediment volume.The analysis of the heavy mineral assemblage reveals an absence of signifi cant contributions from igneous rocks in the sedimentary profi le.Furthermore,the distribution patterns of major,trace,and rare-earth elements in the Shichuanhe River’s argillaceous sediments exhibit similarities to those found in the Weihe River’s sediments.Elemental fractionation patterns suggest that the Shichuanhe River sediments are primarily derived from Loess Plateau sediments,aligning with fi ndings from both the Weihe River and the middle reaches of the Yellow River.
基金supported by the National Natural Science Foundation of China (Nos. 41202154, 41273015)the National Key Technology Research and Development Program (No. 2012BAB03B01)the Fundamental Research Funds for the Central Universities (No. 2015B16914)
文摘The radial sand ridge system （RSRS） located at Jiangsu coast of China attracts much attention on its origin and mechanic of formation for its special structure and potential land resource. Due to complicated hydrodynamic condition, the Jiangsu RSRS is a hot debated on its potential sources, Yangtze River or Yellow River？ We collected ten sand samples from surface sediments along the west coast of Bohai Sea and Yellow Sea from the modern Yellow River estuary to Yangtze River estuary in summer, 2013. The samples are analyzed by method of detrital zircon age for source identification of the RSRS sediments. The U-Pb age spectra of detrital zircon grains of the samples show a wide range from Cenozoic to Late Archean with several age peaks. Comparing the age spectra between the Yangtze River and the Yellow River, the detrital zircons have younger age （〈100 Ma） group in the Yangtze River. These age distribution of the Jiangsu coastal RSRS sediments are similar to that of the Yangtze River, but different from the Yellow River. The samples located adjacent to the old Yellow River Delta show more wide-range age distribution, implying a compounded origination from the both rivers. Based on these findings it is proposed that, contrary to common opinion, the main sediment source of the Jiangsu RSRS is the Yangtze River, rather than the Yellow River. By implication, there should be evidence of hydrodynamic mechanics of oceanic currents and tidal motion. This aspect awaits confirmation in future research.
基金the Swedish International Development Agency (Sida) (Contribution No.75000515) through the "Geology and mineralization of the Precambrian volcanic and associated plutonic rocks of SW Tanzania" project under the Earth Science Programme of CoNAS, University of Dar es Salaam (2009-2013 extended to June 2015)
文摘We present major and trace and Nd-isotopic data of the^1.67 Ga Buanji Group of southwestern Tanzania in order to constrain the nature of their protolith and the intensity of chemical weathering in the source terranes and make inferences on the nature of climatic conditions during the late Paleoproterozoic in the region. Major and trace element contents of the shales from three stratigraphic formations are comparable to those of the post-Archaean Australian Shale(PAAS) and the average Proterozoic Shale(PS). They are characterized by enrichments in LREE relative to HREE((La/Yb)_(CN)=9.07-13.2;(Gd/Yb)cN = 1.51-1.85) and negative Eu anomalies(Eu/Eu~* = 0.61-0.81); features which are comparable to those of PAAS and PS, indicating upper continental sources. Provenance proxy ratios,together with abundances of Cr, Ni, Co and V that increase up-stratigraphy suggest a decreasing input of felsic detritus up-stratigraphy. Chemical Indices of Alteration(CIA) for the lower, middle and upper Buanji formations are 81. 76 and 79, respectively. These indices largely indicate intermediate(ca. 60-80)to extreme(>80) weathering intensities of the precursor rocks. These observations may suggest the prevalence of warm, humid climates during the late Paleoproterozoic in the region.The lower Buanji Formation yielded a depleted mantle Nd model age(T_(DM)) of 、2100 Ma which indicates an Eburnean parentage. T_(DM) ages of 2486-2155 Ma and 2535-2379 Ma obtained from middle and upper Buanji formations, respectively, suggest a progressive increase of sedimentary input from the Tanzania Craton up-stratigraphy. The Eburnean T_(DM) ages of the lower Buanji rocks are attributed to their derivation through denudation of a decaying topographic high composed predominantly of rocks that were generated during the Palaeoproterozoic Ubendian orogenesis, possibly in the realm of Columbian Supercontinent assembly. Overlapping T_(DM) ages between the middle and upper Buanji formations suggest multiple sources involving mixing of detritus from Archaean cratonic rocks and the Palaeoproterozoic Ubendian belt. However, the Archaean signal is relatively more pronounced in the upper Buanji Formation, suggesting sediments derivation from the craton, to the north of the basin. The middle Buanji Formation suggests more diverse protolith,given the relatively larger spread in the T_(DM) ages. The Nb/Ta, Zr/Sm and Ce/Pb ratios coupled with the negative Nb and Ta anomalies, relative to primitive mantle, suggest that the tectonic setting of the source rocks for the Buanji sediments was a subduction zone akin to that generating modern sland Arc Basalts. Thus, we suggest that the Buanji's palaeogeography is consistent with an extensional continental backarc basin during the late Paleoproterozoic.
基金Funding for this project was provided by the China Geological Survey Project(Grant Nos.DD20230316 and DD20190099)Deep Resources Exploration and Mining Project(Grant No.2019YFC0605202).
文摘During the Late Carboniferous to Early Permian,a rift was formed by post-collisional extension after ocean closure or an island arc-related basin formed by Paleo-Asian Ocean(PAO)subduction in the Xi Ujimqin area.Nevertheless,the closure time of the PAO is still under debate.Thus,to identify the origin of the PAO,the geochemistry and U-Pb age of zircons were analyzed for the extra-large deep marine,polymict clastic boulders and sandstones in the Shoushangou Formation within the basin.The analyses revealed magmatic activity and tectonic evolution.The conglomerates include megaclasts of granite(298.8±9.1 Ma)and granodiorite porphyry(297.1±3.1 Ma),which were deposited by muddy debris flow.Results of this study demonstrated that the boulders of granitoids have the geochemistry of typical I-type granite,characterized by low Zr+Nb+Ce+Y and low Ga/Al values.The granitoid boulders were formed in island arc setting,indicating the presence of arc magmatism in the area that is composed of the Late Carboniferous to Early Permian subduction-related granitoid in southern Xi Ujimqin.Multiple diagrams for determining sedimentary provenance using major and trace elements indicate that Shoushangou sediments originated from continental island arc-related felsic rocks.Detrital zircon U-Pb age cluster of 330–280 Ma was obtained,indicating input from granite,ophiolite,Xilin Gol complex,and Carboniferous sources to the south.The basin was geographically developed behind the arc during the Early Permian period because the outcropped intrusive rocks in the Late Carboniferous to Early Permian form a volcanic arc.The comprehensive analyses of source areas suggest that Shoushangou sediments developed in a backarc basin in response to the northward subduction of the PAO.The backarc basin and intrusive rocks,in addition to previously published Late Carboniferous to Early Permian magmatic rocks of arc unit in Xilin Gol,confirm the presence of an Early Permian trencharc-basin system in the region,represented by the Baolidao arc and Xi Ujimqin backarc basin.This study highlights the importance and potential of combined geochemical and geochronological studies of conglomerates and sandstone for reconstructing the geodynamic setting of a basin.
基金Supported by the National Natural Science Foundation of China (Nos.42130206,41302076)the MOST Special Fund awarded by the State Key Laboratory of Continental Dynamics,Northwest University (No.201210128)the Shandong Provincial Key Laboratory of Depositional Mineralization&Sedimentary Mineral,Shandong University of Science and Technology (No.DMSM2017033)。
文摘Six outcrop sections in Fenghe River,Northwestern China,were sampled and analyzed.This study aims to determine provenance,tectonic setting,and source-area paleoweathering of the sediments of Fenghe River in combination of lithofacies analysis and bulk-rock geochemical data.The lithofacies in the studied area were classified as gravel,sand,and fine-grained clastic lithofacies,reflecting generally channel fill deposits,channel bar deposits,and over-bank deposits,respectively.The Chemical Index of Alteration(CIA),Plagioclase Index of Alteration(PIA),and Chemical Index of Weathering(CIW)values ranged 50.10–62.29,50.13–66.35,56.52–71.12,respectively,together with element ratios such as Rb/Sr,K/Na,Rb/K,Th/K,Rb/Ti,and Cs/Ti indicate that the source area was under a low to moderate chemical weathering condition probably in cold and semi-arid climates.Moreover,plot of SiO_(2)vs.(Al_(2)O_(3)+K_(2)O+Na_(2)O)suggests that the sediments were deposited in a semi-arid climate.Plots of Cr/Th vs.Th/Sc,TiO_(2)vs.Zr,La/Yb vs.rare earth element(REE),and La-Th-Sc ternary diagrams,along with the lithology,indicate that the sediments in Fenghe River were mainly originated from felsic igneous rocks.Major elements-based discrimination diagrams and Th-Sc-Zr/10 and La-Th-Sc ternary diagram of the samples indicates that the source rocks of Fenghe River developed in a composite active continental margin and continental island arc field.
基金Islamic Azad University,Khorasgan(Esfahan)Branch grants commission(Grant No.238341892005)
文摘The Aghajari Formation, called also the Upper Fars, develops throughout the Folded Zagros Zone and its thickness in the type section in southwest of Iran is 2966 meters. To analyze the sedimentary basin of this Formation, lithofacies, architectural elements and petrofacies of the related deposits in a section in southeast of Sarvestan in Fars Province of Iran with a thickness of 2221.45 meters were examined. Microscopically studying thin sections, the petrography and the occurrence of the deposits were determined. In this section, 16 lithofacies, 10 architectural elements and 2 sandstone petrofacies were identified. The lithofacies were divided into two major and minor groups, in which the major lithofacies consist of coarse-grained （Gh, Gp, Gt and Gm）, medium-grained （Sh, Sp, St, Sl, Sm, Sr and Ss and fine-grained ones （Fm, Fl and Fsm）, and the minor lithofacies were evaporative and mixed silisiclastic-carbonate. The identified architectural elements are CH, SB, GB, LA, DA, CR, CS, LV, LS, CH （FF） and FF. By combining evidences from facies analysis and architectural elements together, the Aghajari Formation was divided into three parts in which the related sedimentation environments, from top to bottom, are gravel, gravel-sand and fine-grained meandering river respectively. There have also been playas and shoreface in the lower part. Based on petrography, the sandstones of this formation were classified into two groups： litharenite and sublitharenite. The origin of these deposits （sandstones） was appointed to the recycled orogeny and the source of quartz is low and medium to high metamorphic rank. Using the field evidences, the paleocurrent direction was achieved indicating the direction of the paleocurrent from northwest to southeast at the time of deposition. It is hoped that these data can be used in the interpretation of the basin and reconstruction of the paleogeography in the local and regional scales.
文摘The characteristics of sedimentary petrology are significant in determining geological provenance. By using field outcrop observation and indoor identification of thin sections, the characteristics of Jurassic system Tuchengzi Formation clastic rocks exposed in the Beijing Yanqing “flowerpot” basin, which include rock types, clastic composition and cement type, etc. have been analyzed systematically to identify the provenance direction and tectonic setting and nature of the provenance. Research shows that the sedimentary rocks in this area belong to analluvial fan and braided river sedimentary rock system and include mainly conglomerates, lithic sandstone, and feldspathic lithic sandstone. The main compositions of the conglomerate are dolomite and limestone. Nearly 50% to 70% of the sandstones are mainly polycrystalline quartz;10% to 15% are feldspar;and 40% to 55% are composed of debris from mainly magmatic and metamorphic rocks. A Dickinson triangular diagram indicates that the provenance type in this area is recycled orogny evolving from clastic recycled orogeny such as a collisional orogenic belt to a transitional recycled orogeny. On the basis of the geographic position and tectonic setting, three types of provenance can be identified in the Jurassic system Tuchengzi Formation. The far source provenances are Archean erathem basement metamorphic rocks in the northern basin and granite or adamellite that intruded rocks of the Late Jurassic epoch of the Yanshanian period in the northeast. The nearby provenance is the Mesoproterozoic erathem Changchengian system and Jixianianian system dolomite in both the east and west.
基金Financial Support to conduct the Geochemical Analysis in NGRIHyderabad under the Project Contract No.6111264。
文摘The petrographic and geochemical attributes of the Oligocene Barail Group of rocks are used to decipher the likely source area(s)or tectonic domains,as this sequence of rocks was deposited in a foreland basin governed by orogenic domain,namely the North-east Arunachal Himalayas.The river system that gave rise to the Brahmaputra River(Yarlung-Tsangpo),which flowed through several tectonic domains of the Himalayan ranges,primarily from BomiChayu,Gangadese Granitoid,Higher Himalayan Leucogranites,and Namche Barwa into the proto Bengal Basin now a part of Assam Arakan Basin and Naga Schuppen Belt,was the main source of the sandstone formation of the Barail Group.The purpose of sandstone petrography,which combines modal analysis with XRF(Major Oxides)and HR-ICPMS(Trace&Rare Earth Elements)research,is to identify the type of source rock(s),their weathering pattern,and its paleo-environmental circumstances.These sandstones were formed from recycled orogen and include lithic and sublithic arenite variants with advanced texture and chemical maturity.The sediments were felsic(Th/Co:1.38,Cr/Th:9.78,La/Lu:11.58,Th/Sc:0.99,Eu/Eu*:0.66,La/Sc:3.05,La/Co:4.18),with contributions from intermediate source rocks and low-rank metamorphics deposited in an active continental margin to a continental island arc setting.Climatic conditions impacted the sediments of Barails,characterised by being warm and semi-humid to humid which resulted in moderate to a high degree of chemical weathering,as shown by weathering indices like CIA(79.14),PIA(85.47),CIW(86.9),WIP(32.50),ICV(0.71),and Th/U(6.03),which were further additionally supported by C-Value(1.01),PF(1.20),Sr/Cu(2.04),and Rb/Sr(0.97).
