Phosphatic rocks are widely distributed in Neoproterozoic Ediacaran Doushantuo Formation in Yangtze Gorges Area, South China. In this study, rare earth element geochemistry of eight phosphatic rock samples from the Hu...Phosphatic rocks are widely distributed in Neoproterozoic Ediacaran Doushantuo Formation in Yangtze Gorges Area, South China. In this study, rare earth element geochemistry of eight phosphatic rock samples from the Hushan Section has been studied. All the samples display typical hat-shaped REE patterns, moderate negative Ce anomalies（Ce/Ce＊=0.55 to 0.67）, slightly positive Eu anomalies（Eu/Eu＊=1.05 to 1.22） and low Y/Ho ratios（38.2±5.6）. The hat-shaped REE patterns indicate diagenetic alteration of the primary REE signatures, which coincides with detrital siliciclastic sources of REE based on the Y/Ho ratios. The degree of Negative Ce anomalies and positive Eu anomalies may have recorded the redox features of diagenetic fluids, suggesting an anoxic environment during the phosphogenesis processes in Neoproterozoic Ediacaran Doushantuo Formation, South China. The geochemical comparison between the Lower Phosphorite Layer and Upper Phosphorite Layer at Hushan indicates a greater degree of diagenesis occurred in the Upper Layer than the Lower one. Besides the terrigenous sources of REE, organic materials could have also played a role on the REE characteristics.展开更多
Sandstone is a common lithology in a number of groundwater reservoirs.Studying the skeleton sandstone architectural units,therefore,lays the basis for characterizing aquifer systems,groundwater quality,and resource ev...Sandstone is a common lithology in a number of groundwater reservoirs.Studying the skeleton sandstone architectural units,therefore,lays the basis for characterizing aquifer systems,groundwater quality,and resource evaluation.This comprehensive analysis of Cretaceous aquiferous sandstones in the Ordos basin,China,shows that there exists a basin-scale skeleton sandstone in the Luohe Formation which contains 11 isolated barrier beds,12 small skeleton sandstone bodies in Huanhe Formation,and 3 in the Luohandong Formation.The spatial structure and superimposed relationship as well as the medium properties of these skeleton sandstones and isolated barrier beds can be shown by 3D visualization models.Simultaneously,resource quantity can be evaluated with the 3D inquiry functions.The comparison between property models and structural models indicates that the salinity of groundwater of the Luohe Formation has a close connection with the locations of isolated barrier beds that contain abundant gypsum.Through quantitative calculation,groundwater resource of the Cretaceous Luohe and Luohandong formations is estimated to be 1.6×10-(12)m-3,and the total groundwater resource of the Cretaceous system in the Ordos basin is more than 2×10-(12)m-3.展开更多
The material sources and control factors of rare earth elemems （REEs） for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying （borehole number： ZK10-6）, Sichuan Province, South China...The material sources and control factors of rare earth elemems （REEs） for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying （borehole number： ZK10-6）, Sichuan Province, South China, were investigated. All samples were determined by inductively coupled plasma mass spectrometry （ICP-MS）. The chondrite-normalized distribution patterns of mudstone samples are uniform. All samples belong to the light rare earth element （LREE）-rich type and are enriched in LREEs relative to heavy rare earth elements （HREEs）. The distribution curves of REEs in mudstone are highly similar to Mount Emei basalt and the three periods of REEs enrichment correspond to three Mount Emei basalt eruption cycles in Longtan period. The results indicate that REE patterns are not controlled by materials from the seawater or land plants. The predominant sources of REEs are from terrigenous material as indicated by negative Eu anomaly. So, the sources of REEs are controlled by terrigenous material, and the Mount Emei basalt is the predominant source of terrigenous material. Thus, transgression-regression is another control factor of REEs enrichment.展开更多
Zircon U-Pb ages,major and trace elements and Sr-Nd-Hf isotope data of the diabase in the Zhangjiakou District were studied to investigate its derivation and tectonic implications.Zircon U-Pb ages indicate that the di...Zircon U-Pb ages,major and trace elements and Sr-Nd-Hf isotope data of the diabase in the Zhangjiakou District were studied to investigate its derivation and tectonic implications.Zircon U-Pb ages indicate that the diabase was emplaced at∼130 Ma or younger,and captured zircons cluster at∼147,∼240,∼430 and∼465 Ma.The diabase is characterized by minor variations in SiO_(2)(49.35 wt.%–52.10 wt.%),TiO_(2)(1.65 wt.%–1.77 wt.%),Al_(2)O_(3)(17.00 wt.%–18.26 wt.%),MgO(4.28 wt.%–4.93 wt.%),CaO(6.69 wt.%–7.90 wt.%)and Mg^(#)(48–54).It has no significant Eu anomaly and displays enrichment in large ion lithophile elements(Rb,Ba and Sr)and depletion in high field strength elements(Nb,Ta,P and Ti).The diabase exhibits homogeneous Sr((^(87)Sr/^(86)Sr)i=0.70606–0.70701)and Nd(ε_(Nd)(t)=−13.6 to−13.2)isotopic compositions.These features suggest that the parental magma was derived from partial melting of the ancient lower crust,relating to mantle upwelling that was triggered by the stagnant slabs or lithospheric detachment associated with the westward subduction of the Paleo-Pacific Plate.The Early Paleozoic inherited igneous zircons in the diabase suggest that the northern margin of the North China Craton(NCC)likely underwent southward subduction of the Paleo-Asian Ocean.展开更多
Carbonaceous debris(CD)is widely distributed in the sandstone of the Daying Uranium Deposit,northern Ordos Basin,and coexists with uranium minerals,which provides a favorable case for studying their relationship.Vitri...Carbonaceous debris(CD)is widely distributed in the sandstone of the Daying Uranium Deposit,northern Ordos Basin,and coexists with uranium minerals,which provides a favorable case for studying their relationship.Vitrinite reflectance(VR),macerals,moisture,volatile matter,ash,total sulfur(S_t)and uranium concentration of CD within the sandstone were studied.The results show that VR ranges from 0.372%Ro to 0.510%Ro with an average value of 0.438%Ro,indicating that CD is in the stage of lignite.The contents of vitrinite(V),inertinite(I)and minerals range from 83.18%–99.48%,0–7.70%,and 0.34%–15.72%,respectively,with the corresponding average value of 95.51%,1.34%,and 3.15%,respectively which indicates that V is the major maceral.Moisture on air dried basis(M_(ad)),volatile matter yield on dry,ash-free basis(V_(daf)),ash yield on dried basis(A_d)and S_t mostly range from 7.95%–16.09%,44.70%–66.54%,4.84%–26.24% and 0.24%–1.12%,respectively,while their average values are 12.43%,53.41%,16.57% and 0.77%,respectively.It suggests that CD is of medium-high moisture,super-high volatile matter,low-medium ash and low sulfur.Uranium concentration ranges from 29 ppm to 92 ppm with an average value of 50 ppm,and uranium concentration increases with the decreased distance to CD.On the whole,M_(ad )and V_(daf) decrease with increasing burial depth,which indicates that CD experienced the burial metamorphism.However,M_(ad) and V_(daf) obviously decrease in uranium-rich areas whereas A_d and S_(t )noticeably increase.Comprehensive studies suggest that there is a certain relationship between uranium enrichment and CD.CD in the stage of lignite helps the adsorption of uranium.On one hand,radioactivity uranium enrichment makes organic matter maturation increase with a decrease in moisture and volatile matter.On the other hand,an increase in organic matter maturation,caused by radioactivity uranium enrichment,results in an increase in uranium minerals,which is instructive in the study of regional uranium mineralization and metallogenic regularity.展开更多
The Jiangla'angzong granite in the northern part of the Central Lhasa Terrane is composed of syenogranite and adamellite.LA-ICP-MS zircon U-Pb analyses suggest that syenogranite has a weighted mean 2±6pb/23SU...The Jiangla'angzong granite in the northern part of the Central Lhasa Terrane is composed of syenogranite and adamellite.LA-ICP-MS zircon U-Pb analyses suggest that syenogranite has a weighted mean 2±6pb/23SU age of 86±1 Ma(mean square weighted deviation=0.37),which is in accordance with the muscovite Ar-Ar age(85±1 Ma)of Cu-Au ore-bearing skarns and the zircon U-Pb age(84±1 Ma)of adamellite.This suggests that the Jiangla'angzong magmatism and Cu-Au mineralization events took place during the Late Cretaceous.The granite contains hornblende,biotite,and pyroxene,and does not contain Al-bearing minerals,such as muscovite,cordierite,and garnet.It has high contents of SiO2(65.10-70.91wt%),K20(3.44-5.17wt%),and total K20+Na20(7.13-8.15wt%),and moderate contents of A12Oa(14.14-16.45wt%)and CaO(2.33-4.11wt%),with a Reitman index(δ43)of 2.18 to 2.33,and A/CNK values of 0.88 to 1.02.The P205 contents show a negative correlation with SiO2,whereas Pb contents show a positive correlation with SiO2.Th and Y contents are relatively low and show a negative correlation with the Rb contents.These characteristics suggest that the Jiangla'angzong granite is a high K calc-alkaline metaluminous I-type granite.It is enriched in light rare earth elements(LREE)and large ion lithofile elements(LILE),and depleted in heavy rare earth elements(HREE)and high field strength elements(HFSE),with LREE/HREE ratios of 11.7 to 18.1.The granite has negative Eu anomalies of 0.58 to 0.94 without obvious Ce anomalies(δCe=l.00-1.04).The relatively low initial a7Sr/a6Sr ratios of 0.7106 to 0.7179,positiveε±nt(t)values of 1.0 to 4.1,and two-stage Hf model ages(TDM2)ranging from 889 Ma to 1082 Ma,These geochemical features indicate that the granite derived from a juvenile crust.The(143Nd/144Nd)t values from the Jiangla'angzong granite range from 0.5121 to 0.5123,its eNd(t)values range from-10.17 to-6.10,its(^206pb/^204pb)t values range from 18.683 to 18.746,its(^207pb/^204pb)t values range from 15.695 to 15.700,and its(^208pb/^204pb)t values range from 39.012 to 39.071.These data indicate that the granite was formed by melting of the upper crust with the addition of some mantle materials.We propose that the Jiangla'angzong granite was formed during the post-collision extension of the Qiangtang and Lhasa terranes.展开更多
A systematic analysis of southwestern Ordos Basin's sedimentary characteristics,internal architectural element association styles and depositional model was illustrated through core statistics,well logging data an...A systematic analysis of southwestern Ordos Basin's sedimentary characteristics,internal architectural element association styles and depositional model was illustrated through core statistics,well logging data and outcrop observations in Chang 8 oil-bearing group.This analysis indicates that shallow water delta sediments dominated by a fluvial system is the primary sedimentary system of the Chang 8 oil-bearing group of the Yanchang Formation in southwestern Ordos Basin.Four microfacies with fine grain sizes are identified: distributary channels,sheet sandstone,mouth bar and interdistributary fines.According to the sandbody's spatial distribution and internal architecture,two types of sandbody architectural element associations are identified: amalgamated distributary channels and thin-layer lobate sandstone.In this sedimentary system,net-like distributary channels at the delta with a narrow ribbon shape compose the skeleton of the sandbody that extends further into the delta front and shades into contiguous lobate distribution sheet sandstone in the distal delta front.The mouth bar is largely absent in this system.By analyzing the palaeogeomorphology,the palaeostructure background,sedimentary characteristics,sedimentary facies types and spatial distribution of sedimentary facies during the Chang 8 period,a distinctive depositional model of the Chang 8 shallow water fluvial-dominated delta was established,which primarily consists of straight multi-phase amalgamated distributary channels in the delta plain,net-like distributary channels frequently diverting and converging in the proximal delta front,sheet sandstones with dispersing contiguous lobate shapes in the distal delta front,and prodelta or shallow lake mudstones.展开更多
The gravity flow deposit were mainly developed in the lowstand systems tract（LST） of the first member of Upper Miocene Huangliu Formation（Ehl1） in Dongfang area, Yinggehai Basin, has become a valuable target for g...The gravity flow deposit were mainly developed in the lowstand systems tract（LST） of the first member of Upper Miocene Huangliu Formation（Ehl1） in Dongfang area, Yinggehai Basin, has become a valuable target for gas exploration and production. The gravity flow sedimentary characteristics of lithofacies associations, sedimentary texture, seismic facies and logging facies were described in detail on the basis of integrated analysis of cores, logging and seismic data. The sedimentary microfacies types composed of neritic sandbar, continental shelf mud, main channel, bifurcated or cross-cutting distributary channel, overspill, and natural levee are revealed under the constraint of high resolution sequence stratigraphic framework in the Ehl1. The gravity flow deposit system in the LST is divided into three evolution stages corresponding to periods of three parasequence sets. The gravity flow deposit was induced in the early LST, expanded rapidly in the middle LST and decreased slightly in the late LST. But its developing scale decreased sharply in the transgression systems tract（TST） and finally vanished in the highstand systems tract（HST）. This spatial evolution rule is constrained by the integrated function of sediments supply of the Vietnam Blue River in the LST, the development of local gradient change in sea floor（micro-topography, i.e., flexure slope break）, and the fall in relative sea level. On the basics of the deep study of the coupling relationship among the three main control factors, the sedimentary model is established as an optimal component of ＂source-channel-sink＂ for shallow marine turbidite submarine fan.展开更多
The Qiongdongnan Basin（QDNB） is situated in the extensional zone at the vertex of the V-shaped northwest sub-basin, non-volcanic northern margin of the South China Sea（SCS）. From north to south, the thickness of t...The Qiongdongnan Basin（QDNB） is situated in the extensional zone at the vertex of the V-shaped northwest sub-basin, non-volcanic northern margin of the South China Sea（SCS）. From north to south, the thickness of the continental lithosphere decreases from 22 km on the northern continental shelf to 17 km at the deepest area of the central depression. A sharp change on the crustal structure is of importance to hydrocarbon exploration yet the dynamic causes remain unknown. A comprehensive study including （1） interpretation of seismic profiles,（2） P-wave velocity data modeling, and （3） magnetic anomalies analysis reveals that there are some high-density intrusions along the lithospheric thinning belt. Chaotic reflections can be found in the southwest of the QDNB, with a low velocity（〈3.4 km/s）, while in the center and the east, the intensively deformed strata passing towards the diapir flanks and their high velocities（〉6 km/s） suggest the existence of igneous diapirs. Diapirism differentiation are primarily achieved through analysis of the contact relationship and the thickness variations in the surrounding strata. The first phase of diapirism along the Songnan low uplift occurred in the Late Mesozoic, and the second phase of diapirism in a form of subsequent gas movement remained active until the Late Quaternary. The distribution and the evolution of the diapirs would have major implications for post-rift emplacement.展开更多
The Huaniushan granite is located at the Beishan orogenic belt, northwestern China. At the contact zone between the granite and marble, a hydrothermal Pb-Zn and skarn Au deposit is formed. LA-ICP-MS zircon U-Pb dating...The Huaniushan granite is located at the Beishan orogenic belt, northwestern China. At the contact zone between the granite and marble, a hydrothermal Pb-Zn and skarn Au deposit is formed. LA-ICP-MS zircon U-Pb dating yielded a weighted mean 206Pb/238U age of 229.5±2.6 Ma (MSDW=0.93) for the Huaniushan granite, imply-ing its Late Triassic intrusion. Geochemistry analyses show that the Huaniushan granite is enriched in Si, K, Na, and REE, and depleted in Mg and Ca, with contents of SiO2 (70.8% to 74.4%), Na2O+K2O (8.8% to 10.2%), CaO (0.93% to 1.44%), and MgO (0.14% to 0.48%). REE is characterized by obvious negative Eu anomaly. Rb, Th, U, K, Pb, Nb, Zr and Hf elements are rich in the granite while Ba, Sr, P, Ti and Eu are deplete. The granite has a high (Zr+Nb+Ce+Y) abundance and 104 Ga/Al ratios. Petrology, major and trace elements data all indicate that the Hua-niushan granite is A-type granite which intruded in a post-collisional extensional tectonic setting. The magma was dominantly sourced from partial melting of crustal intermediate-felsic igneous rocks. Intensive magmatic activities and Au-Cu-Mo mineralization occurred throughout the Beishan orogenic belt during the period from ca. 240 to 220 Ma.展开更多
Using regional geological, newly acquired 2D and 3D seismic, drilling and well log data, especially 2D long cable seismic profiles, the structure and stratigraphy in the deep-water area of Qiongdongnan Basin are inter...Using regional geological, newly acquired 2D and 3D seismic, drilling and well log data, especially 2D long cable seismic profiles, the structure and stratigraphy in the deep-water area of Qiongdongnan Basin are interpreted. The geometry of No.2 fault system is also re-defined, which is an important fault in the central depression belt of the deep-water area in the Qiongdongnan Basin by employing the quantitative analysis techniques of fault activity and backstripping. Furthermore, the dynamical evolution of the No.2 fault sys-tem and its controls on the central depression belt are analyzed. This study indicates that the Qiongdongnan Basin was strongly influenced by the NW-trending tensile stress field during the Late Eocene. At this time, No.2 fault system initiated and was characterized by several discontinuous fault segments, which controlled a series small NE-trending fault basins. During the Oligocene, the regional extensional stress field changed from NW-SE to SN with the oceanic spreading of South China Sea, the early small faults started to grow along their strikes, eventually connected and merged as the listric shape of the No.2 fault system as ob-served today. No.2 fault detaches along the crustal Moho surface in the deep domain of the seismic profiles as a large-scale detachment fault. A large-scale rollover anticline formed in hanging wall of the detachment fault. There are a series of small fault basins in both limbs of the rollover anticline, showing that the early small basins were involved into fold deformation of the rollover anticline. Structurally, from west to east, the central depression belt is characterized by alternatively arranged graben and half-graben. The central depression belt of the Qiongdongnan Basin lies at the extension zone of the tip of the V-shaped northwest-ern ocean sub-basin of the South China Sea, its activity period is the same as the development period of the northwestern ocean sub-basin, furthermore the emplacement and eruption of magma that originated from the mantle below the Moho surface occurred at the region between Songnan-Baodao and Changchang sags, from east to west with the early-stage spreading of the South China Sea. Therefore, this study not only helps in depicting the structural features and evolution of the deep-water basin in the Qiongdongnan Basin, but also provides the geological and structural evidence for establishing a unified model of continental margin extension and oceanic spreading.展开更多
The Nanpu（南堡） sag has previously been modeled as（1） a pull-apart basin,（2） a rift ba-sin,without significant strike-slip deformation,and（3） a transtensional basin.We present a new model for the Nanpu sag in ...The Nanpu（南堡） sag has previously been modeled as（1） a pull-apart basin,（2） a rift ba-sin,without significant strike-slip deformation,and（3） a transtensional basin.We present a new model for the Nanpu sag in which the basin is a transtensional fault-termination basin.Although transten-sional fault-termination basins is an important basin type,it is not as well studied as other classic basin types.On the base of 3D seismic data interpretation,the faults geometries and kinematics and their controls on depocenters are presented.The Nanpu sag is developed in the context of dextral transten-sion of the Bohai（渤海） Bay basin and attributed to a transtensional fault-termination basin.During deposition of the Es3-Es2 members,the basin border Xi＇nanzhuang（西南庄） fault and Baigezhuang（柏各庄） fault linked to a mixed normal and strike-slip fault system,or a linked fault system controlled the basin by dominant extension and weak strike-slip and created fan-shaped depocenters surrounded by the two faults.From Es1 Member to Dongying（东营） Formation,two major depocenters controlled by two mixed normal and sinistral strike-slip fault systems are located on the Linque（林雀） and Caofeidian（曹妃甸） subsags.During deposition of the Guantao（馆陶）-Minghuazhen（明化镇） Forma-tion,the Nanpu sag successively developed and significantly expanded.展开更多
This study reports the sphalerite Rb-Sr age and LA-MC-ICP-MS in situ sulfur isotope analysis results of the Daliangzi Lead-Zinc Deposit in the Sichuan-Yunnan-Guizhou （SYG） triangle. Sphalerite Rb-Sr dating yields a ...This study reports the sphalerite Rb-Sr age and LA-MC-ICP-MS in situ sulfur isotope analysis results of the Daliangzi Lead-Zinc Deposit in the Sichuan-Yunnan-Guizhou （SYG） triangle. Sphalerite Rb-Sr dating yields a Mississippian age of 345.2±3.6 Ma （MSWD=I.4）, which is older than the published Late Triassic mineralization ages （230-200 Ma） of some other deposits. This indicates that at least two stages of lead-zinc mineralization have occurred in the SYG lead-zinc triangle. The first stage occurred in the Mississippian under an extensional environment, while the second stage occurred in the Late Triassic under a compressional environment. In situ sulfur isotope analysis of sphalerite growth zoning presents relatively large δ^34S values of 11.3‰-15.2‰ with small variations. The large δ^34S values indicate a reduced sulfur source of thermochemical reduction of seawater sulfates. Abundant organic matter in the black fracture zone possibly supplied reductants for thermochemical sulfate reduction （TSR） at the mineralization site. The small variation of δ^34S values suggests a slow and stable TSR process that could prevent the sudden supersaturation of sphalerite in the fluid and the resulting of fast participation. This is consistent with the well-crystallized characteristic of the sphalerite of the Daliangzi Deposit.展开更多
In active rift basins, tectonism is extremely important for sequence stratigraphic patterns, affecting both the sequence architecture and internal makeup. Sequence stratigraphic framework of a Paleogene rift successio...In active rift basins, tectonism is extremely important for sequence stratigraphic patterns, affecting both the sequence architecture and internal makeup. Sequence stratigraphic framework of a Paleogene rift succession in Qiongdongnan Basin, northern South China Sea, was built using seismic profiles, complemented by well logs and cores. One first-order and three second-order sequences were identified on the basis of basin-scale unconformities, and seven third-order sequences are defined by unconformities along the basin margins and correlative conformities within the central basin. Through unconformity analysis and backstripping procedure, the Paleogene synrift tectonic evolution of deep- water area of Qiongdongnan Basin was proved to be episodic, which can be divided into rifting stage-I, rifting stage-II and rifting stage-III. Episodic rifting resulted in the formation of various types of struc- tural slope break belts, which controlled different architectures and internal makeup of sequences. This study enhances the understanding of the control of tectonic evolution on sequence stratigraphic pat- terns and establishes relevant patterns in a typical rift basin, and further proposes the favorable sand- stone reservoirs developing in different sequence stratigraphic patterns, which will be pretty helpful for subtle pool exploration in deepwater area of petroliferous basins.展开更多
No substantial breakthroughs have been made in hydrocarbon exploration of the South Yellow Sea Basin.It is believed that the Mesozoic-Paleozoic marine sedimentary formation in the South Yellow Sea Basin is similar to ...No substantial breakthroughs have been made in hydrocarbon exploration of the South Yellow Sea Basin.It is believed that the Mesozoic-Paleozoic marine sedimentary formation in the South Yellow Sea Basin is similar to that in the Sichuan Basin.Therefore,outcrop,drilling,and seismic data were determined and compared with the research results on petroleum geological conditions in the Yangtze land area,and the hydrocarbon geological conditions were analyzed comprehensively from multiple aspects,such as basin evolution and main source rocks,reservoir characteristics,preservation conditions,and structural traps.The results show that two main stages in the South Yellow Sea Basin(the stable evolution stage of the Mesozoic-Paleozoic marine basin and the Mesozoic-Cenozoic tectonic reformation and basin formation stage)were important for the development and evolution of four sets of main source rocks.Reservoirs dominated by carbonate rocks,three sets of capping beds with good sealing capability,relatively weak magmatic activity,and multiple types of structural traps jointly constituted relatively good hydrocarbon-reservoir-forming conditions.There were four sets of main source-reservoir-cap assemblages and three possible hydrocarbon reservoir types(primary residual-type hydrocarbon reservoir,shallow reformed-type hydrocarbon reservoir,and composite-type hydrocarbon reservoir)developed in the marine strata.It is concluded that the marine strata in the South Yellow Sea Basin have relatively good hydrocarbon potential.The Laoshan Uplift is characterized by stable structure,complete preserved source reservoir cap assemblage,and large structural traps,and thus it is the preferred prospect zone for marine Paleozoic hydrocarbon exploration in this area.展开更多
Characteristics of atmospheric VOCs(volatile organic compounds) have been extensively studied in megacities in China, however, they are scarcely investigated in medium/smallsized cities in North China Plain(NCP).A com...Characteristics of atmospheric VOCs(volatile organic compounds) have been extensively studied in megacities in China, however, they are scarcely investigated in medium/smallsized cities in North China Plain(NCP).A comprehensive research on possible sources of VOCs was conducted in a medium-sized city of NCP, from May to September 2019.A total of 143 canister samples of 8 sites in Xuchang city were collected, and 57 VOC species were detected.The average VOC concentrations were 42.6 ± 31.6 μg/m3, with 53.7 ± 31.0 μg/m3 and 32.1 ± 27.8 μg/m^(3), in the morning and afternoon, respectively.Alkenes and aromatics contributed 80% of the total ozone formation potential(OFP).Aromatics accounted for more than 95% of secondary organic aerosol potential(SOAP).VOCs were dominated by the local emission with significant transport from the southeast direction.PMF analysis extracted 6 sources, which were combustion(33.1%), LPG usage(19.3%), vehicular exhaust & fuel evaporation(15.8%), solvent usage(15.2%), industrial(9.11%) and biogenic(7.51%), respectively and they contributed 33.4%, 17.6%, 12.9%, 18.6%, 9.28% and 8.22% to the OFP, respectively.Combustion and LPG usage were the dominant VOC sources;and combustion, solvent usage and LPG usage were the main sources of OFP in Xuchang city, which were different to megacities in China with a high contribution from vehicular exhaust, solvent usage and industry,suggesting specific control strategies on VOCs need to be implemented in medium-sized city such as Xuchang city.展开更多
The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic–Paleozoic strata are widely distributed.The latest geophysical data were used to overcome the limitation of previous poor...The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic–Paleozoic strata are widely distributed.The latest geophysical data were used to overcome the limitation of previous poor-quality deep data.Meanwhile,the geological characteristics of hydrocarbon reservoirs in the marine Mesozoic–Paleozoic strata in the South Yellow Sea Basin were analyzed by comparing the source rocks and the reservoir and utilizing drilling and outcrop data.It is believed that the South Yellow Sea Basin roughly underwent six evolutionary stages:plate spreading,plate convergence,stable platform development,foreland basin development,faulted basin development,and depression basin development.The South Yellow Sea Basin has characteristics of a composite platform-fault depression geological structure,with a half-graben geological structure and with a ‘sandwich structure' in the vertical direction.Four sets of hydrocarbon source rocks developed – the upper Permian Longtan–Dalong formation,the lower Permian Qixia formation,the lower Silurian Gaojiabian formation,and the lower Cambrian Hetang formation/Mufushan formation,giving the South Yellow Sea Basin relatively good hydrocarbon potential.The carbonate is the main reservoir rock type in the South Yellow Sea area,and there are four carbonate reservoir types:porous dolomitic,reef-bank,weathered crust,and fractured.There are reservoir-forming horizons similar to the typical hydrocarbon reservoirs in the Yangtze land area developed in the South Yellow Sea,and there are three sets of complete source-reservoir-cap rock assemblages developed in the marine strata,with very good hydrocarbon potential.展开更多
Shadong deposit is the first large-scale tungsten deposit found in the East Tianshan orogenic belt, and the geologic characteristics of the deposit indicate that the deeply concealed granite body is ge- netically rela...Shadong deposit is the first large-scale tungsten deposit found in the East Tianshan orogenic belt, and the geologic characteristics of the deposit indicate that the deeply concealed granite body is ge- netically related with the mineralization. The LA-ICPMS U-Pb age of zircons from the Shadong concealed granite obtained in this research is 239±2.0 Ma, belonging to the Middle Triassic. The whole rock samples are metaiuminous to slightly peraluminous （A/CNK=0.95-1.02） with low contents of SiO2 （64.0 wt.%-68.5 wt.%） and low K2O/Na2O ratios （0.73-0.96）. The samples reveal enrichment of K, Rb, Th and depletion of Nb, Ta, P, Ti and have a negative slope from La to Lu （LaN/YbN=16.29-36.8） with weak negative Eu anom- aly （Eu/Eu＊= 0.71-0.82）. Initial ^87Sr/^86Sr ratios of whole rock range of 0.706 59-0.707 75, eNd（t） values range from -1.77 to -2.53 and εnf（t） values of zircon are between 2.54 and 4.90. The lithogeochemistry and Sr-Nd-Hf isotopic characteristics revealed that the concealed granite in Shadong tungsten deposit is I-type granite, and occurs in an intraplate tectonic setting. The magma mixing during intraplating of mantle de- rived magma intruding into the crust in Indosinian Period is the major formation mechanism of the granite. Of which, the proportion of mantle derived magma ranges from 58% to 60%, and the crustal materials are mainly the metamorphic basement of Xingxingxia Group of Mesoproterozoic Changcheng System, which may orovide the main source of ore forming metals of Shadong tungsten deposit.展开更多
There are a wide range of magmatism and mineralization in the Yunkai area of South China during the Late Yanshanian Period, including the newly discovered Michang, Youmapo, Sanchaehong and Songwang porphyry-skarn W-Mo...There are a wide range of magmatism and mineralization in the Yunkai area of South China during the Late Yanshanian Period, including the newly discovered Michang, Youmapo, Sanchaehong and Songwang porphyry-skarn W-Mo deposits. In this study, we obtained zircon U-Pb ages of the ore-bearing biotite granites and their mafic enclaves from 884-1 to 1104-1 Ma. Zircons from the granites show Hf isotopic compositions with negative C-Hf（t） values of -5.9 to -0.6 and calculated Hf model ages （TvM2） of 1.5-1.2 Ga; indicating that the Middle Proterozoic crustal materials may have provided an important source for the magmatic rocks in this district during the Late Yanshanian Period, whereas zircons from the mafic enclaves show positive era（t） values of 1.3 to 10.1 with younger Hf model ages （TDM2） of 0.5-1.1 Ga, suggesting a mantle component may have involved in the granitic magma generation. Sulfur isotope study of the sulfide minerals from the W-Mo deposits show a narrow 834S distribution with most data ranging from -4.2%0 to 5.2‰. In addition, this study reports the first Fe isotopic compositions of pyrite in the W-Mo deposits, which show a uniform distribution range with the values near zero （656Fe=0.16‰-0.58‰, average 0.35‰; 657Fe=0.02‰-0.54‰, average 0.48‰）. These data indicate that the ore-forming materials may come from the deep-sourced granitic magma, and the mineralizations show a close relationship with the granitic magmatism during the Late Yanshanian Period. Combining with previous results, we suggest that there is a widespread porphyry-skarn W-Mo mineralization in the Yunkai area during the Late Cretaceous （80-110 Ma）, which has a close relationship with the Late Yanshanian magmatism that may have formed during the rollback of the subducted Pacific Plate.展开更多
The Huangling （黄陵） massif is an important area to understand the tectonic evolution of the northern Middle Yangtze Block. Integrating previously published thermochronology data with new zircon and apatite fission ...The Huangling （黄陵） massif is an important area to understand the tectonic evolution of the northern Middle Yangtze Block. Integrating previously published thermochronology data with new zircon and apatite fission track, and apatite （U-Th）/He thermochronometry, the Meso- Cenozoic exhumation history of the Huangling massif has been quantitatively studied. Based on the data and the time-temperature thermal history modelling results, the exhumation process of the Huangling massif can be divided into four stages： the slow cooling stage during 200-150 Ma; the rapid cooling event at ca. 150-80 Ma; a period of relative thermal stability during ca. 80-40 Ma, and an increase in cooling thereafter. Two rapid cooling/exhumation indicate two tectonic events in the northern Middle Yangtze Block. The rapid exhumation between ca. 150-80 Ma is likely related to a wide range Cretaceous intra-continental reactive and deformation in the eastern China. The accelerated cooling after ca. 40-30 Ma may result from a far-field effect of the India-Asia collision.展开更多
基金supported by projects from the National Natural Science Foundation of China (Nos. 41230102,41273009)the National 973 project (No. 2013CB835000)
文摘Phosphatic rocks are widely distributed in Neoproterozoic Ediacaran Doushantuo Formation in Yangtze Gorges Area, South China. In this study, rare earth element geochemistry of eight phosphatic rock samples from the Hushan Section has been studied. All the samples display typical hat-shaped REE patterns, moderate negative Ce anomalies（Ce/Ce＊=0.55 to 0.67）, slightly positive Eu anomalies（Eu/Eu＊=1.05 to 1.22） and low Y/Ho ratios（38.2±5.6）. The hat-shaped REE patterns indicate diagenetic alteration of the primary REE signatures, which coincides with detrital siliciclastic sources of REE based on the Y/Ho ratios. The degree of Negative Ce anomalies and positive Eu anomalies may have recorded the redox features of diagenetic fluids, suggesting an anoxic environment during the phosphogenesis processes in Neoproterozoic Ediacaran Doushantuo Formation, South China. The geochemical comparison between the Lower Phosphorite Layer and Upper Phosphorite Layer at Hushan indicates a greater degree of diagenesis occurred in the Upper Layer than the Lower one. Besides the terrigenous sources of REE, organic materials could have also played a role on the REE characteristics.
基金sponsored by the Special Fund for Geological Survey of the Central Government(No.12120115013701)the National Important Basic Research Program of China(No.2015CB453003)China Geological Survey Project(No.1212010331302ZT6)
文摘Sandstone is a common lithology in a number of groundwater reservoirs.Studying the skeleton sandstone architectural units,therefore,lays the basis for characterizing aquifer systems,groundwater quality,and resource evaluation.This comprehensive analysis of Cretaceous aquiferous sandstones in the Ordos basin,China,shows that there exists a basin-scale skeleton sandstone in the Luohe Formation which contains 11 isolated barrier beds,12 small skeleton sandstone bodies in Huanhe Formation,and 3 in the Luohandong Formation.The spatial structure and superimposed relationship as well as the medium properties of these skeleton sandstones and isolated barrier beds can be shown by 3D visualization models.Simultaneously,resource quantity can be evaluated with the 3D inquiry functions.The comparison between property models and structural models indicates that the salinity of groundwater of the Luohe Formation has a close connection with the locations of isolated barrier beds that contain abundant gypsum.Through quantitative calculation,groundwater resource of the Cretaceous Luohe and Luohandong formations is estimated to be 1.6×10-(12)m-3,and the total groundwater resource of the Cretaceous system in the Ordos basin is more than 2×10-(12)m-3.
基金Project(40839910) supported by the National Natural Science Foundation of China
文摘The material sources and control factors of rare earth elemems （REEs） for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying （borehole number： ZK10-6）, Sichuan Province, South China, were investigated. All samples were determined by inductively coupled plasma mass spectrometry （ICP-MS）. The chondrite-normalized distribution patterns of mudstone samples are uniform. All samples belong to the light rare earth element （LREE）-rich type and are enriched in LREEs relative to heavy rare earth elements （HREEs）. The distribution curves of REEs in mudstone are highly similar to Mount Emei basalt and the three periods of REEs enrichment correspond to three Mount Emei basalt eruption cycles in Longtan period. The results indicate that REE patterns are not controlled by materials from the seawater or land plants. The predominant sources of REEs are from terrigenous material as indicated by negative Eu anomaly. So, the sources of REEs are controlled by terrigenous material, and the Mount Emei basalt is the predominant source of terrigenous material. Thus, transgression-regression is another control factor of REEs enrichment.
基金supported by the National Natural Science Foundation of China(No.42003032)the State Key Laboratory of Nuclear Resources and Environment,East China University of Technology(No.2020Z10).
文摘Zircon U-Pb ages,major and trace elements and Sr-Nd-Hf isotope data of the diabase in the Zhangjiakou District were studied to investigate its derivation and tectonic implications.Zircon U-Pb ages indicate that the diabase was emplaced at∼130 Ma or younger,and captured zircons cluster at∼147,∼240,∼430 and∼465 Ma.The diabase is characterized by minor variations in SiO_(2)(49.35 wt.%–52.10 wt.%),TiO_(2)(1.65 wt.%–1.77 wt.%),Al_(2)O_(3)(17.00 wt.%–18.26 wt.%),MgO(4.28 wt.%–4.93 wt.%),CaO(6.69 wt.%–7.90 wt.%)and Mg^(#)(48–54).It has no significant Eu anomaly and displays enrichment in large ion lithophile elements(Rb,Ba and Sr)and depletion in high field strength elements(Nb,Ta,P and Ti).The diabase exhibits homogeneous Sr((^(87)Sr/^(86)Sr)i=0.70606–0.70701)and Nd(ε_(Nd)(t)=−13.6 to−13.2)isotopic compositions.These features suggest that the parental magma was derived from partial melting of the ancient lower crust,relating to mantle upwelling that was triggered by the stagnant slabs or lithospheric detachment associated with the westward subduction of the Paleo-Pacific Plate.The Early Paleozoic inherited igneous zircons in the diabase suggest that the northern margin of the North China Craton(NCC)likely underwent southward subduction of the Paleo-Asian Ocean.
基金supported by the 973 Project (No. 2015CB453003)Open Fund of Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education (No. TPR-2015-09)+2 种基金Geological Survey Foundation of Ministry of Finance of the People’s Republic of China (No. 12120115013701)Natural Science Foundation of China (No. 41502105)Fundamental Research Funds for the Central Universities, China University of Geosciences(Wuhan) (No. G1323511660)
文摘Carbonaceous debris(CD)is widely distributed in the sandstone of the Daying Uranium Deposit,northern Ordos Basin,and coexists with uranium minerals,which provides a favorable case for studying their relationship.Vitrinite reflectance(VR),macerals,moisture,volatile matter,ash,total sulfur(S_t)and uranium concentration of CD within the sandstone were studied.The results show that VR ranges from 0.372%Ro to 0.510%Ro with an average value of 0.438%Ro,indicating that CD is in the stage of lignite.The contents of vitrinite(V),inertinite(I)and minerals range from 83.18%–99.48%,0–7.70%,and 0.34%–15.72%,respectively,with the corresponding average value of 95.51%,1.34%,and 3.15%,respectively which indicates that V is the major maceral.Moisture on air dried basis(M_(ad)),volatile matter yield on dry,ash-free basis(V_(daf)),ash yield on dried basis(A_d)and S_t mostly range from 7.95%–16.09%,44.70%–66.54%,4.84%–26.24% and 0.24%–1.12%,respectively,while their average values are 12.43%,53.41%,16.57% and 0.77%,respectively.It suggests that CD is of medium-high moisture,super-high volatile matter,low-medium ash and low sulfur.Uranium concentration ranges from 29 ppm to 92 ppm with an average value of 50 ppm,and uranium concentration increases with the decreased distance to CD.On the whole,M_(ad )and V_(daf) decrease with increasing burial depth,which indicates that CD experienced the burial metamorphism.However,M_(ad) and V_(daf) obviously decrease in uranium-rich areas whereas A_d and S_(t )noticeably increase.Comprehensive studies suggest that there is a certain relationship between uranium enrichment and CD.CD in the stage of lignite helps the adsorption of uranium.On one hand,radioactivity uranium enrichment makes organic matter maturation increase with a decrease in moisture and volatile matter.On the other hand,an increase in organic matter maturation,caused by radioactivity uranium enrichment,results in an increase in uranium minerals,which is instructive in the study of regional uranium mineralization and metallogenic regularity.
基金financially supported by the National Key Research and Development Program of China(Grant No.2016YFC0600308,SQ2018YFC060162)the China Geological Survey Project(Grant No.DD20160015,DD20160026)+1 种基金the International Scientific Plan of the Qinghai Xizang(Tibet)Plateau of Chengdu Center,China Geological Surveythe Natural Science Foundation of China(Grant No.41702080,41702086)
文摘The Jiangla'angzong granite in the northern part of the Central Lhasa Terrane is composed of syenogranite and adamellite.LA-ICP-MS zircon U-Pb analyses suggest that syenogranite has a weighted mean 2±6pb/23SU age of 86±1 Ma(mean square weighted deviation=0.37),which is in accordance with the muscovite Ar-Ar age(85±1 Ma)of Cu-Au ore-bearing skarns and the zircon U-Pb age(84±1 Ma)of adamellite.This suggests that the Jiangla'angzong magmatism and Cu-Au mineralization events took place during the Late Cretaceous.The granite contains hornblende,biotite,and pyroxene,and does not contain Al-bearing minerals,such as muscovite,cordierite,and garnet.It has high contents of SiO2(65.10-70.91wt%),K20(3.44-5.17wt%),and total K20+Na20(7.13-8.15wt%),and moderate contents of A12Oa(14.14-16.45wt%)and CaO(2.33-4.11wt%),with a Reitman index(δ43)of 2.18 to 2.33,and A/CNK values of 0.88 to 1.02.The P205 contents show a negative correlation with SiO2,whereas Pb contents show a positive correlation with SiO2.Th and Y contents are relatively low and show a negative correlation with the Rb contents.These characteristics suggest that the Jiangla'angzong granite is a high K calc-alkaline metaluminous I-type granite.It is enriched in light rare earth elements(LREE)and large ion lithofile elements(LILE),and depleted in heavy rare earth elements(HREE)and high field strength elements(HFSE),with LREE/HREE ratios of 11.7 to 18.1.The granite has negative Eu anomalies of 0.58 to 0.94 without obvious Ce anomalies(δCe=l.00-1.04).The relatively low initial a7Sr/a6Sr ratios of 0.7106 to 0.7179,positiveε±nt(t)values of 1.0 to 4.1,and two-stage Hf model ages(TDM2)ranging from 889 Ma to 1082 Ma,These geochemical features indicate that the granite derived from a juvenile crust.The(143Nd/144Nd)t values from the Jiangla'angzong granite range from 0.5121 to 0.5123,its eNd(t)values range from-10.17 to-6.10,its(^206pb/^204pb)t values range from 18.683 to 18.746,its(^207pb/^204pb)t values range from 15.695 to 15.700,and its(^208pb/^204pb)t values range from 39.012 to 39.071.These data indicate that the granite was formed by melting of the upper crust with the addition of some mantle materials.We propose that the Jiangla'angzong granite was formed during the post-collision extension of the Qiangtang and Lhasa terranes.
基金Project(SQ2013CB021013)supported by the National Key Basic Research Program of ChinaProject(41002045)supported by the National Natural Science Foundation of China
文摘A systematic analysis of southwestern Ordos Basin's sedimentary characteristics,internal architectural element association styles and depositional model was illustrated through core statistics,well logging data and outcrop observations in Chang 8 oil-bearing group.This analysis indicates that shallow water delta sediments dominated by a fluvial system is the primary sedimentary system of the Chang 8 oil-bearing group of the Yanchang Formation in southwestern Ordos Basin.Four microfacies with fine grain sizes are identified: distributary channels,sheet sandstone,mouth bar and interdistributary fines.According to the sandbody's spatial distribution and internal architecture,two types of sandbody architectural element associations are identified: amalgamated distributary channels and thin-layer lobate sandstone.In this sedimentary system,net-like distributary channels at the delta with a narrow ribbon shape compose the skeleton of the sandbody that extends further into the delta front and shades into contiguous lobate distribution sheet sandstone in the distal delta front.The mouth bar is largely absent in this system.By analyzing the palaeogeomorphology,the palaeostructure background,sedimentary characteristics,sedimentary facies types and spatial distribution of sedimentary facies during the Chang 8 period,a distinctive depositional model of the Chang 8 shallow water fluvial-dominated delta was established,which primarily consists of straight multi-phase amalgamated distributary channels in the delta plain,net-like distributary channels frequently diverting and converging in the proximal delta front,sheet sandstones with dispersing contiguous lobate shapes in the distal delta front,and prodelta or shallow lake mudstones.
基金supported by the National Natural Science Foundation of China (NSFC) (Nos. 41272122, 41202074, 41172123 and 40702023)the National Twelfth Five-Year Major Projects of Oil and Gas (No. 2011ZX05025-002-02-02)+1 种基金the Key Laboratory of Tectonics and Petroleum Resources (CUG)of Ministry of Education open issue (No. TPR-2013-08)the China University of Geosciences (Wuhan) Teaching Labor atory open funded projects
文摘The gravity flow deposit were mainly developed in the lowstand systems tract（LST） of the first member of Upper Miocene Huangliu Formation（Ehl1） in Dongfang area, Yinggehai Basin, has become a valuable target for gas exploration and production. The gravity flow sedimentary characteristics of lithofacies associations, sedimentary texture, seismic facies and logging facies were described in detail on the basis of integrated analysis of cores, logging and seismic data. The sedimentary microfacies types composed of neritic sandbar, continental shelf mud, main channel, bifurcated or cross-cutting distributary channel, overspill, and natural levee are revealed under the constraint of high resolution sequence stratigraphic framework in the Ehl1. The gravity flow deposit system in the LST is divided into three evolution stages corresponding to periods of three parasequence sets. The gravity flow deposit was induced in the early LST, expanded rapidly in the middle LST and decreased slightly in the late LST. But its developing scale decreased sharply in the transgression systems tract（TST） and finally vanished in the highstand systems tract（HST）. This spatial evolution rule is constrained by the integrated function of sediments supply of the Vietnam Blue River in the LST, the development of local gradient change in sea floor（micro-topography, i.e., flexure slope break）, and the fall in relative sea level. On the basics of the deep study of the coupling relationship among the three main control factors, the sedimentary model is established as an optimal component of ＂source-channel-sink＂ for shallow marine turbidite submarine fan.
基金supported by the National Natural Science Foundation of China (No. 41272121)the Major National Science and Technology Programs in the "Twelfth Five-Year" Plan of China (No. 2011ZX05025-002-02-02)the Fundamental Research Funds for the Central Universities (No. 16CX02038A)
文摘The Qiongdongnan Basin（QDNB） is situated in the extensional zone at the vertex of the V-shaped northwest sub-basin, non-volcanic northern margin of the South China Sea（SCS）. From north to south, the thickness of the continental lithosphere decreases from 22 km on the northern continental shelf to 17 km at the deepest area of the central depression. A sharp change on the crustal structure is of importance to hydrocarbon exploration yet the dynamic causes remain unknown. A comprehensive study including （1） interpretation of seismic profiles,（2） P-wave velocity data modeling, and （3） magnetic anomalies analysis reveals that there are some high-density intrusions along the lithospheric thinning belt. Chaotic reflections can be found in the southwest of the QDNB, with a low velocity（〈3.4 km/s）, while in the center and the east, the intensively deformed strata passing towards the diapir flanks and their high velocities（〉6 km/s） suggest the existence of igneous diapirs. Diapirism differentiation are primarily achieved through analysis of the contact relationship and the thickness variations in the surrounding strata. The first phase of diapirism along the Songnan low uplift occurred in the Late Mesozoic, and the second phase of diapirism in a form of subsequent gas movement remained active until the Late Quaternary. The distribution and the evolution of the diapirs would have major implications for post-rift emplacement.
基金founded by the National Science and Technology Support Program,China(Grant No.2011BAB06B04-05)
文摘The Huaniushan granite is located at the Beishan orogenic belt, northwestern China. At the contact zone between the granite and marble, a hydrothermal Pb-Zn and skarn Au deposit is formed. LA-ICP-MS zircon U-Pb dating yielded a weighted mean 206Pb/238U age of 229.5±2.6 Ma (MSDW=0.93) for the Huaniushan granite, imply-ing its Late Triassic intrusion. Geochemistry analyses show that the Huaniushan granite is enriched in Si, K, Na, and REE, and depleted in Mg and Ca, with contents of SiO2 (70.8% to 74.4%), Na2O+K2O (8.8% to 10.2%), CaO (0.93% to 1.44%), and MgO (0.14% to 0.48%). REE is characterized by obvious negative Eu anomaly. Rb, Th, U, K, Pb, Nb, Zr and Hf elements are rich in the granite while Ba, Sr, P, Ti and Eu are deplete. The granite has a high (Zr+Nb+Ce+Y) abundance and 104 Ga/Al ratios. Petrology, major and trace elements data all indicate that the Hua-niushan granite is A-type granite which intruded in a post-collisional extensional tectonic setting. The magma was dominantly sourced from partial melting of crustal intermediate-felsic igneous rocks. Intensive magmatic activities and Au-Cu-Mo mineralization occurred throughout the Beishan orogenic belt during the period from ca. 240 to 220 Ma.
基金The National Science and Technology Major Project of China under contract No.2011ZX05025-002-02the National Natural Sci-ence Foundation of China under contract Nos 41272121,91028009 and 41102071
文摘Using regional geological, newly acquired 2D and 3D seismic, drilling and well log data, especially 2D long cable seismic profiles, the structure and stratigraphy in the deep-water area of Qiongdongnan Basin are interpreted. The geometry of No.2 fault system is also re-defined, which is an important fault in the central depression belt of the deep-water area in the Qiongdongnan Basin by employing the quantitative analysis techniques of fault activity and backstripping. Furthermore, the dynamical evolution of the No.2 fault sys-tem and its controls on the central depression belt are analyzed. This study indicates that the Qiongdongnan Basin was strongly influenced by the NW-trending tensile stress field during the Late Eocene. At this time, No.2 fault system initiated and was characterized by several discontinuous fault segments, which controlled a series small NE-trending fault basins. During the Oligocene, the regional extensional stress field changed from NW-SE to SN with the oceanic spreading of South China Sea, the early small faults started to grow along their strikes, eventually connected and merged as the listric shape of the No.2 fault system as ob-served today. No.2 fault detaches along the crustal Moho surface in the deep domain of the seismic profiles as a large-scale detachment fault. A large-scale rollover anticline formed in hanging wall of the detachment fault. There are a series of small fault basins in both limbs of the rollover anticline, showing that the early small basins were involved into fold deformation of the rollover anticline. Structurally, from west to east, the central depression belt is characterized by alternatively arranged graben and half-graben. The central depression belt of the Qiongdongnan Basin lies at the extension zone of the tip of the V-shaped northwest-ern ocean sub-basin of the South China Sea, its activity period is the same as the development period of the northwestern ocean sub-basin, furthermore the emplacement and eruption of magma that originated from the mantle below the Moho surface occurred at the region between Songnan-Baodao and Changchang sags, from east to west with the early-stage spreading of the South China Sea. Therefore, this study not only helps in depicting the structural features and evolution of the deep-water basin in the Qiongdongnan Basin, but also provides the geological and structural evidence for establishing a unified model of continental margin extension and oceanic spreading.
基金supported by the National Natural Science Foundation of China (No. 40402014)
文摘The Nanpu（南堡） sag has previously been modeled as（1） a pull-apart basin,（2） a rift ba-sin,without significant strike-slip deformation,and（3） a transtensional basin.We present a new model for the Nanpu sag in which the basin is a transtensional fault-termination basin.Although transten-sional fault-termination basins is an important basin type,it is not as well studied as other classic basin types.On the base of 3D seismic data interpretation,the faults geometries and kinematics and their controls on depocenters are presented.The Nanpu sag is developed in the context of dextral transten-sion of the Bohai（渤海） Bay basin and attributed to a transtensional fault-termination basin.During deposition of the Es3-Es2 members,the basin border Xi＇nanzhuang（西南庄） fault and Baigezhuang（柏各庄） fault linked to a mixed normal and strike-slip fault system,or a linked fault system controlled the basin by dominant extension and weak strike-slip and created fan-shaped depocenters surrounded by the two faults.From Es1 Member to Dongying（东营） Formation,two major depocenters controlled by two mixed normal and sinistral strike-slip fault systems are located on the Linque（林雀） and Caofeidian（曹妃甸） subsags.During deposition of the Guantao（馆陶）-Minghuazhen（明化镇） Forma-tion,the Nanpu sag successively developed and significantly expanded.
基金financially supported by the China Geological Survey (No. 12120114019701)the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan)
文摘This study reports the sphalerite Rb-Sr age and LA-MC-ICP-MS in situ sulfur isotope analysis results of the Daliangzi Lead-Zinc Deposit in the Sichuan-Yunnan-Guizhou （SYG） triangle. Sphalerite Rb-Sr dating yields a Mississippian age of 345.2±3.6 Ma （MSWD=I.4）, which is older than the published Late Triassic mineralization ages （230-200 Ma） of some other deposits. This indicates that at least two stages of lead-zinc mineralization have occurred in the SYG lead-zinc triangle. The first stage occurred in the Mississippian under an extensional environment, while the second stage occurred in the Late Triassic under a compressional environment. In situ sulfur isotope analysis of sphalerite growth zoning presents relatively large δ^34S values of 11.3‰-15.2‰ with small variations. The large δ^34S values indicate a reduced sulfur source of thermochemical reduction of seawater sulfates. Abundant organic matter in the black fracture zone possibly supplied reductants for thermochemical sulfate reduction （TSR） at the mineralization site. The small variation of δ^34S values suggests a slow and stable TSR process that could prevent the sudden supersaturation of sphalerite in the fluid and the resulting of fast participation. This is consistent with the well-crystallized characteristic of the sphalerite of the Daliangzi Deposit.
基金supported by the National Science Foundation of China (NSFC) (Nos. 41272122, 41202074 and 41172123)the Major National Science and Technology Programs in the "Twelfth Five-Year" Plan of China (No. 2011ZX05009-002-02)+1 种基金the Open Research Program Foundation of Teaching Laboratory of China University of Geosciencesthe Foundation of Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences) of Ministry of Education (No. TPR-2013-14)
文摘In active rift basins, tectonism is extremely important for sequence stratigraphic patterns, affecting both the sequence architecture and internal makeup. Sequence stratigraphic framework of a Paleogene rift succession in Qiongdongnan Basin, northern South China Sea, was built using seismic profiles, complemented by well logs and cores. One first-order and three second-order sequences were identified on the basis of basin-scale unconformities, and seven third-order sequences are defined by unconformities along the basin margins and correlative conformities within the central basin. Through unconformity analysis and backstripping procedure, the Paleogene synrift tectonic evolution of deep- water area of Qiongdongnan Basin was proved to be episodic, which can be divided into rifting stage-I, rifting stage-II and rifting stage-III. Episodic rifting resulted in the formation of various types of struc- tural slope break belts, which controlled different architectures and internal makeup of sequences. This study enhances the understanding of the control of tectonic evolution on sequence stratigraphic pat- terns and establishes relevant patterns in a typical rift basin, and further proposes the favorable sand- stone reservoirs developing in different sequence stratigraphic patterns, which will be pretty helpful for subtle pool exploration in deepwater area of petroliferous basins.
基金supported by the Project of China Geological Survey (Nos. DD20160152, DD20160147, GZH 200800503, DD20190818)the National Natural Science Foundation of China (Nos. 41506080, 41702162)+1 种基金the Project of China Ministry of Land and Resources (Nos. XQ2005-01, 2009GYXQ10)the Postdoctoral Innovation Fund Project of Shandong Province (No. 201602004)
文摘No substantial breakthroughs have been made in hydrocarbon exploration of the South Yellow Sea Basin.It is believed that the Mesozoic-Paleozoic marine sedimentary formation in the South Yellow Sea Basin is similar to that in the Sichuan Basin.Therefore,outcrop,drilling,and seismic data were determined and compared with the research results on petroleum geological conditions in the Yangtze land area,and the hydrocarbon geological conditions were analyzed comprehensively from multiple aspects,such as basin evolution and main source rocks,reservoir characteristics,preservation conditions,and structural traps.The results show that two main stages in the South Yellow Sea Basin(the stable evolution stage of the Mesozoic-Paleozoic marine basin and the Mesozoic-Cenozoic tectonic reformation and basin formation stage)were important for the development and evolution of four sets of main source rocks.Reservoirs dominated by carbonate rocks,three sets of capping beds with good sealing capability,relatively weak magmatic activity,and multiple types of structural traps jointly constituted relatively good hydrocarbon-reservoir-forming conditions.There were four sets of main source-reservoir-cap assemblages and three possible hydrocarbon reservoir types(primary residual-type hydrocarbon reservoir,shallow reformed-type hydrocarbon reservoir,and composite-type hydrocarbon reservoir)developed in the marine strata.It is concluded that the marine strata in the South Yellow Sea Basin have relatively good hydrocarbon potential.The Laoshan Uplift is characterized by stable structure,complete preserved source reservoir cap assemblage,and large structural traps,and thus it is the preferred prospect zone for marine Paleozoic hydrocarbon exploration in this area.
基金supported by the National Natural Science Foundation of China (Nos.41675127, 41475116)。
文摘Characteristics of atmospheric VOCs(volatile organic compounds) have been extensively studied in megacities in China, however, they are scarcely investigated in medium/smallsized cities in North China Plain(NCP).A comprehensive research on possible sources of VOCs was conducted in a medium-sized city of NCP, from May to September 2019.A total of 143 canister samples of 8 sites in Xuchang city were collected, and 57 VOC species were detected.The average VOC concentrations were 42.6 ± 31.6 μg/m3, with 53.7 ± 31.0 μg/m3 and 32.1 ± 27.8 μg/m^(3), in the morning and afternoon, respectively.Alkenes and aromatics contributed 80% of the total ozone formation potential(OFP).Aromatics accounted for more than 95% of secondary organic aerosol potential(SOAP).VOCs were dominated by the local emission with significant transport from the southeast direction.PMF analysis extracted 6 sources, which were combustion(33.1%), LPG usage(19.3%), vehicular exhaust & fuel evaporation(15.8%), solvent usage(15.2%), industrial(9.11%) and biogenic(7.51%), respectively and they contributed 33.4%, 17.6%, 12.9%, 18.6%, 9.28% and 8.22% to the OFP, respectively.Combustion and LPG usage were the dominant VOC sources;and combustion, solvent usage and LPG usage were the main sources of OFP in Xuchang city, which were different to megacities in China with a high contribution from vehicular exhaust, solvent usage and industry,suggesting specific control strategies on VOCs need to be implemented in medium-sized city such as Xuchang city.
基金supported by the National Natural Science Foundation of China(No.41506080)the Project of China Geological Survey(Nos.DD20160152,DD20160147,and GZH200800503)+1 种基金the Project of China Ministry of Land and Resources(Nos.XQ-2005-01,and 2009GYXQ10)the Postdoctoral Innovation Fund Project of Shandong Province(No.201602004)
文摘The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic–Paleozoic strata are widely distributed.The latest geophysical data were used to overcome the limitation of previous poor-quality deep data.Meanwhile,the geological characteristics of hydrocarbon reservoirs in the marine Mesozoic–Paleozoic strata in the South Yellow Sea Basin were analyzed by comparing the source rocks and the reservoir and utilizing drilling and outcrop data.It is believed that the South Yellow Sea Basin roughly underwent six evolutionary stages:plate spreading,plate convergence,stable platform development,foreland basin development,faulted basin development,and depression basin development.The South Yellow Sea Basin has characteristics of a composite platform-fault depression geological structure,with a half-graben geological structure and with a ‘sandwich structure' in the vertical direction.Four sets of hydrocarbon source rocks developed – the upper Permian Longtan–Dalong formation,the lower Permian Qixia formation,the lower Silurian Gaojiabian formation,and the lower Cambrian Hetang formation/Mufushan formation,giving the South Yellow Sea Basin relatively good hydrocarbon potential.The carbonate is the main reservoir rock type in the South Yellow Sea area,and there are four carbonate reservoir types:porous dolomitic,reef-bank,weathered crust,and fractured.There are reservoir-forming horizons similar to the typical hydrocarbon reservoirs in the Yangtze land area developed in the South Yellow Sea,and there are three sets of complete source-reservoir-cap rock assemblages developed in the marine strata,with very good hydrocarbon potential.
基金financially supported by the National Key Technology Research and Development Program of China (No. 2011BAB06B04)
文摘Shadong deposit is the first large-scale tungsten deposit found in the East Tianshan orogenic belt, and the geologic characteristics of the deposit indicate that the deeply concealed granite body is ge- netically related with the mineralization. The LA-ICPMS U-Pb age of zircons from the Shadong concealed granite obtained in this research is 239±2.0 Ma, belonging to the Middle Triassic. The whole rock samples are metaiuminous to slightly peraluminous （A/CNK=0.95-1.02） with low contents of SiO2 （64.0 wt.%-68.5 wt.%） and low K2O/Na2O ratios （0.73-0.96）. The samples reveal enrichment of K, Rb, Th and depletion of Nb, Ta, P, Ti and have a negative slope from La to Lu （LaN/YbN=16.29-36.8） with weak negative Eu anom- aly （Eu/Eu＊= 0.71-0.82）. Initial ^87Sr/^86Sr ratios of whole rock range of 0.706 59-0.707 75, eNd（t） values range from -1.77 to -2.53 and εnf（t） values of zircon are between 2.54 and 4.90. The lithogeochemistry and Sr-Nd-Hf isotopic characteristics revealed that the concealed granite in Shadong tungsten deposit is I-type granite, and occurs in an intraplate tectonic setting. The magma mixing during intraplating of mantle de- rived magma intruding into the crust in Indosinian Period is the major formation mechanism of the granite. Of which, the proportion of mantle derived magma ranges from 58% to 60%, and the crustal materials are mainly the metamorphic basement of Xingxingxia Group of Mesoproterozoic Changcheng System, which may orovide the main source of ore forming metals of Shadong tungsten deposit.
基金supported by the Fundamental Research Funds for the Central Universities (No. CUG120702)
文摘There are a wide range of magmatism and mineralization in the Yunkai area of South China during the Late Yanshanian Period, including the newly discovered Michang, Youmapo, Sanchaehong and Songwang porphyry-skarn W-Mo deposits. In this study, we obtained zircon U-Pb ages of the ore-bearing biotite granites and their mafic enclaves from 884-1 to 1104-1 Ma. Zircons from the granites show Hf isotopic compositions with negative C-Hf（t） values of -5.9 to -0.6 and calculated Hf model ages （TvM2） of 1.5-1.2 Ga; indicating that the Middle Proterozoic crustal materials may have provided an important source for the magmatic rocks in this district during the Late Yanshanian Period, whereas zircons from the mafic enclaves show positive era（t） values of 1.3 to 10.1 with younger Hf model ages （TDM2） of 0.5-1.1 Ga, suggesting a mantle component may have involved in the granitic magma generation. Sulfur isotope study of the sulfide minerals from the W-Mo deposits show a narrow 834S distribution with most data ranging from -4.2%0 to 5.2‰. In addition, this study reports the first Fe isotopic compositions of pyrite in the W-Mo deposits, which show a uniform distribution range with the values near zero （656Fe=0.16‰-0.58‰, average 0.35‰; 657Fe=0.02‰-0.54‰, average 0.48‰）. These data indicate that the ore-forming materials may come from the deep-sourced granitic magma, and the mineralizations show a close relationship with the granitic magmatism during the Late Yanshanian Period. Combining with previous results, we suggest that there is a widespread porphyry-skarn W-Mo mineralization in the Yunkai area during the Late Cretaceous （80-110 Ma）, which has a close relationship with the Late Yanshanian magmatism that may have formed during the rollback of the subducted Pacific Plate.
基金supported by the Open Research Funding of Key Laboratory of Tectonics and Petroleum Resources, Minis-try of Education, China University of Geosciences (Wuhan)(No. TPR-2012-25)the China Geological Survey (No.12120113094200)the Fundamental Research Funds for the Central Universities, China University of Geosciences(Wuhan), China (No. CUGL130104)
文摘The Huangling （黄陵） massif is an important area to understand the tectonic evolution of the northern Middle Yangtze Block. Integrating previously published thermochronology data with new zircon and apatite fission track, and apatite （U-Th）/He thermochronometry, the Meso- Cenozoic exhumation history of the Huangling massif has been quantitatively studied. Based on the data and the time-temperature thermal history modelling results, the exhumation process of the Huangling massif can be divided into four stages： the slow cooling stage during 200-150 Ma; the rapid cooling event at ca. 150-80 Ma; a period of relative thermal stability during ca. 80-40 Ma, and an increase in cooling thereafter. Two rapid cooling/exhumation indicate two tectonic events in the northern Middle Yangtze Block. The rapid exhumation between ca. 150-80 Ma is likely related to a wide range Cretaceous intra-continental reactive and deformation in the eastern China. The accelerated cooling after ca. 40-30 Ma may result from a far-field effect of the India-Asia collision.
