The Wangjiazhuang Cu(-Mo)deposit,located within the Zouping volcanic basin in western Shandong Province,China,is unique in this area for having an economic value.In order to expound the metallogenetic characteristics ...The Wangjiazhuang Cu(-Mo)deposit,located within the Zouping volcanic basin in western Shandong Province,China,is unique in this area for having an economic value.In order to expound the metallogenetic characteristics of this porphyry-like hydrothermal deposit,a detailed fluid inclusion study has been conducted,employing the techniques of representative sampling,fluid inclusion petrography,microthermometry,Raman spectroscopy,LA-ICP-MS analysis of single fluid inclusions,as well as cathode fluorescence spectrometer analysis of host mineral quartz.The deposit contains mainly two types of orebodies,i.e.veinlet-dissemination-stockwork orebodies in the K-Si alteration zone and pegmatiticquartz sulfide veins above them.In addition,minor breccia ore occurs locally.Four types of fluid inclusions in the deposit and altered quartz monzonite are identified:L-type one-or two-phase aqueous inclusions,V-type vapor-rich inclusions with V/L ratios greater than 50%-90%,D-type multiphase fluid inclusions containing daughter minerals or solids and S-type silicate-bearing fluid inclusions containing mainly muscovite and biotite.Ore petrography and fluid inclusion study has revealed a three-stage mineralization process,driven by magmatic-hydrothermal fluid activity,as follows.Initially,a hydrothermal fluid,separated from the parent magma,infiltrated into the quartz monzonite,resulting in its extensive K-Si alteration,as indicated by silicate-bearing fluid inclusions trapped in altered quartz monzonite.This is followed by the early mineralization,the formation of quartz veinlets and dissemination-stockwork ores.During the main mineralization stage,due to the participation and mixing of meteoric groundwater with magmatic-sourced hydrothermal fluid,the cooling and phase separation caused deposition of metals from the hydrothermal fluids.As a result,the pegmatitic-quartz sulfide-vein ores formed.In the late mineralization stage,decreasing fluid salinity led to the formation of L-type aqueous inclusions and chalcopyrite-sulfosalt ore.Coexistence of V-type and D-type inclusions and their similar homogenization temperatures with different homogenization modes suggest that phase separation or boiling of the ore-forming fluids took place during the early and the main mineralization stages.The formation P-T conditions of S-type inclusions and the early and the main mineralization stages were estimated as ca.156-182 MPa and 450-650℃,350-450℃,18-35 MPa and 280-380℃,8-15 MPa,respectively,based on the microthermometric data of the fluid inclusions formed at the individual stages.展开更多
The Ordos Basin is the largest petroliferous basin in China, where the Chang 7 Member shale serves as the major source rock in the basin, with an area of more than 100,000 km^2 So far, sedimentary and geochemical char...The Ordos Basin is the largest petroliferous basin in China, where the Chang 7 Member shale serves as the major source rock in the basin, with an area of more than 100,000 km^2 So far, sedimentary and geochemical characterizations have rarely been conducted on the shale in shallow(< 1000 m) areas in the southeastern part of the basin, but such characterizations can help identify the genesis of organic-rich shale and promote the prediction and recovery of shale oil. In this paper,several outcrop sections of the Chang 7 Member in the Tongchuan area were observed and sampled, and sedimentary and geochemical characterizations were conducted for the well-outcropped YSC section. The study results show that the Chang7 Member shale is widely distributed laterally with variable thickness. The organic-rich shale is 7-25 m thick in total and exhibits obvious horizontal variation in mineral composition. In the eastern sections, the shale contains organic matter of TypeⅡ_2-Ⅲ and is low in thermal maturity, with high clay mineral content, low K-feldspar content, and no pyrite. In the western sections, the shale contains Type Ⅱ_1 organic matter and is low in thermal maturity, with high clay mineral, K-feldspar, and pyrite contents. The YSC section reveals three obvious intervals in vertical mineral composition and organic abundance.The Chang 7 Member organic-rich shale(TOC > 10%) contains mainly sapropelite and liptinite, with Type Ⅱ kerogen. It is generally characterized by a hydrocarbon potential of more than 70 mg/g, low maturity, and shallow-semideep lacustrine facies. In the western sections, the shale, still in a low maturity stage, has a higher hydrocarbon potential and is optional for shale oil recovery. However, the Chang 7 Member shale in the study area is highly heterogeneous and its shale oil recovery is practical only in the organic-rich intervals.展开更多
Abundant aromatic fractions were detected in oils from the Linnan subsag, including aphthalenes, phenanthrenes, triaromatic steroids, biphenyl, fluorenes, dibenzothiophenes, dibenzofuranes, as well as some typical hig...Abundant aromatic fractions were detected in oils from the Linnan subsag, including aphthalenes, phenanthrenes, triaromatic steroids, biphenyl, fluorenes, dibenzothiophenes, dibenzofuranes, as well as some typical higher plant-sourced compounds, such as pyrene, benzopyrene, fluoranthene, chryaene, benzofluoranthrene, perylene and cadalene. Occurrences of biomarkers indicate that oils from the Linnan subsag are typical terrestrially genetic oils. Developed in the depositional environment is a strong reduction condition typical of brackish-saline lake. Thermal evolution has entered into the mature-high mature stage.展开更多
Core samples from the deeply buried Ordovician Majiagou Formation below the Huainan Coalfield(E China) have been investigated for their carbonate types,major and trace elements(including rare earth elements) and C and...Core samples from the deeply buried Ordovician Majiagou Formation below the Huainan Coalfield(E China) have been investigated for their carbonate types,major and trace elements(including rare earth elements) and C and O isotopes,The objective was to get a better insight into the possible occurrences of gas(and possibly oil) derived from Carboniferous coals.It was found that the carbonates are dolomites with strongly varying amounts of CaO and MgO.The low concentrations of SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3)indicate deposition in a normal marine environment with little terrigenous input,The Na_(2)O/K_(2)O,Fe/Mn and Sr/Ba ratios,as well as the Ga values indicate mainly a marine salinity and a hot and humid climate.The slight depletion of Ce and Eu,the depletion of heavy rare earth elements(HREE) and the enrichment of light rare earth elements(LREE) indicate deposition in a reducing environment.It thus appears that the Majiagou Formation below the Huainan Coalfield closely resembles that in the eastern part of the Ordos Basin,where several gas reservoirs are present,so that the Majiagou Formation under the Huainan Coalfield represents a promising target for hydrocarbon exploration.展开更多
The>2000 km Indus-Yarlung Tsangpo suture zone(IYSZ)is composed of the Neo-tethys oceanic remnants,flysch units and related continental rocks,which has been regarded as the boundary between the Eurasian and Indian t...The>2000 km Indus-Yarlung Tsangpo suture zone(IYSZ)is composed of the Neo-tethys oceanic remnants,flysch units and related continental rocks,which has been regarded as the boundary between the Eurasian and Indian terranes.Among the ophiolitic complexes,the Purang ophiolite is the biggest massif in the IYSZ,and many studies have been conducted on this ophiolite.However,previous studies have mainly focused on harzburgite,clinopyroxenite and dunite.Field observations show that mafic dykes were emplaced within the Purang ophiolite.However,petrogenetic evolutions of those mafic dykes are poorly understood.In this study,we present new LA-ICP-MS zircon U-Pb dating results,whole-rock geochemistry and Sr-Nd-Hf isotope analyses for microgabbro,gabbro and dolerite dykes from the Purang ophiolite of the southwestern IYSZ,respectively.Three samples yielded zircon U-Pb ages of144.2±2.1 Ma.127.9±2.3 Ma and 126.5±0.42 Ma,suggesting two different phases of magmatic activities distinctly.Whole-rock geochemical results suggest that the gabbro samples show alkaline features marked by enrichments of light rare earth elements(LREE)and large-ion lithophile elements(LILE),as well as Nb-Ta elements,suggesting an oceanic island basalt-like(OIB-like)geochemical affinity.However,the dolerite and microgabbro samples demonstrate sub-alkaline characteristics with normal mid-oceanic ridge basalt-like(N-MORB-like)geochemical features.Three distinct mafic dykes show significant Rb element depletion.The geochemical data and Sr-Nd-Hf isotopic features suggest that the microgabbro and gabbro rocks were derived from a depleted mantle that had been metasomatized by partial melts of sediments and enriched slab-derived fluids.The dolerite was also originated from a depleted mantle marked by significantly depleted Sr-Nd-Hf compositions,which was not influenced by enriched slab-derived fluids and sediments contamination during subsequent evolution.The isotope and geochemical data and tectonic diagrams suggest a tectonic transition from a within-plate to a midoceanic ridge basalt-like(MORB-like)setting during the period from ca.144 Ma to 127 Ma.Combined with regional background and this study,we propose that these mafic dykes were formed in an oceanic back-arc basin setting.Additionally,integrated with previous studies,we suggest that the geodynamic evolution of the southwestern and central parts of the Neo-Tethys oceanic basin is comparable in Early Cretaceous.展开更多
The Upper Ordovician Wufeng-Lower Silurian Longmaxi and the Lower Cambrian Qiongzhusi shales are the major targets for shale gas exploration and development in China.Although the two organic-rich shales share similar ...The Upper Ordovician Wufeng-Lower Silurian Longmaxi and the Lower Cambrian Qiongzhusi shales are the major targets for shale gas exploration and development in China.Although the two organic-rich shales share similar distribution ranges and thicknesses,they exhibit substantially different exploration and development results.This work analyzed the nanopore structures of the shale reservoirs in this region.Pore development of 51 shale samples collected from various formations and locations was compared using the petromineralogical,geochemical,structural geological and reservoir geological methods.The results indicate that the reservoir space in these shales is dominated by organic pores and the total pore volume of micropores,mesopores,macropores in different tectonic areas and formations show different trends with the increase of TOC.It is suggested that organic pores of shale can be well preserved in areas with simple structure and suitable preservation conditions,and the shale with smaller maximum ancient burial depth and later hydrocarbongeneration-end-time is also more conducive to pore preservation.Organic pore evolution models are established,and they are as follows:①Organic matter pore development stage,②Early stage of organic matter pore destruction,and③late stage of organic matter pore destruction.The areas conducive to pore development are favorable for shale gas development.Research results can effectively guide the optimization and evaluation of favorable areas of shale gas.展开更多
It is becoming an important controlling factor of gas exploration and exploitation in the east part of Sulige gas field in the Ordos Basin where the reservoir of main gas formations is tight sandstones. Employing expe...It is becoming an important controlling factor of gas exploration and exploitation in the east part of Sulige gas field in the Ordos Basin where the reservoir of main gas formations is tight sandstones. Employing experimental methods of slice identification, casting slice, scan electron microscope, and X-ray diffrac- tions, we studied the characteristics of petrology and diagenesis on reservoirs in Shanl section of Shanxi formation and He8 section of Shihezi formation of the Permian system in the East II part of Sulige gas field. The results include： （1） the main sandstones in these areas are dominated by lithic sandstone and litbic silicarenite with low grade of maturity; （2） the diagenesis of sandstone in these areas mainly include compaction, cementation, corrosion and alteration. Conclusions are as follows： （1） the diagenetic stage reached period B of the middle diagenetic stage; （2） the early diagenetic compaction is one of the main factors to decreasing porosity; （3） the secondary pores formed by corrosion in acidity medium con- ditions in period A of the middle diagenetic stage can distinctly ameliorate the poor reservoir capability of sandstone and, （4） cementation in period B of the middle diagenetic stage is the most important factor leading; to poor physical property of sandstone reservoirs.展开更多
Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially f...Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially for source rocks which have high-over level of thermal maturity. Systematic identification of original organism assemblages of the Lower Paleozoic potential source rocks and detailed carbon isotopic composition of kerogen analyses were conducted for four outcrop sections in the Tarim basin. Results indicated that the original organism assemblages of the lower part of the Lower Cambrian were composed mainly of benthic algae, whereas those of the Upper Cambrian and the Ordovician were characterized by planktonic algae. Kerogen carbon isotopic data demonstrated that the δ13 Ckerogen values of source rocks dominated by benthic algae are lower than-34‰, whereas the δ13 Ckerogen values of source rocks dominated by planktonic algae are higher than-30‰ in general. We tentatively suggested that the carbon species those are utilized by algae and the carbon isotopic fractionation during photosynthesis are the major controls for the δ13 Ckerogen values in the Lower Paleozoic source rocks in the Tarim basin. Correlating the δ13 C values of oils exploited in the Tarim basin, the original organism assemblages, and δ13 Ckerogen values of source rocks, it implied that the Lower Paleozoic oils exploited in the Tarim basin should be sourced from the source rocks with original organism assemblages dominated by planktonic algae, and the hydrocarbon sourced from the Cambrian benthic algae should be of great exploration potential in future. Original organism assemblages in source rocks can provide important clues for oil-source rocks correlation, especially for the source rocks with high thermal maturity.展开更多
The analysis of early stage rodingite from the ultramafic rocks of the Xialu Massif in the Xigaze Ophiolite,Tibet,in China shows that the rodingitization involved continuous changes in fluid composition during differe...The analysis of early stage rodingite from the ultramafic rocks of the Xialu Massif in the Xigaze Ophiolite,Tibet,in China shows that the rodingitization involved continuous changes in fluid composition during different stages of subduction.The early stage prehnite-bearing rodingite was produced at low pressures and temperatures along extensional fractures.Samples of rodingite were collected along a profile from the center to the margin of a rodingitized intrusive igneous rock(^10 m×30 m),and they record wide variations in bulk composition,mineralogy,and texture.The mineral assemblages,from center to margin,vary from(1)relics of primary clinopyroxene(Cpx_(r))and primary amphibole(Amp_(r))+newly formed late amphibole(Act)+primary plagioclase(Pl_(r))+clinozoisite+prehnite+albite+chlorite+titanite+ilmenite(R1 rodingite),through(2)relics of primary clinopyroxene(Cpx_(r))+newly formed late clinopyroxene(Cpx_(n))+primary and late amphiboles(Amp_(r)+Act)+clinozoisite+prehnite+albite+chlorite+titanite(R2 rodingite),to(3)newly formed late clinopyroxene(Cpx_(n))and amphibole(Act)+clinozoisite+prehnite+albite+chlorite+titanite(R3 rodingite).As a result of the metasomatic process of rodingitization,the content of CaO in the whole rock chemical composition from R1 to R3 increases,SiO_(2) decreases,and Na_(2)O+K_(2)O is almost completely removed.Massbalance diagrams show enrichments in large ion lithophile elements such as Rb,Cs,Ba,and Pb as well as Ni during rodingitization.The central part of the rodingitized intrusion(R1 rodingite)was only slightly affected by metasomatism.On the other hand,the contents of the rare earth elements(REEs),high field strength elements(HFSEs;e.g.Zr,Nb,Ta,Hf,and Y),and some highly compatible elements such as Cr and Sc decreased slightly during rodingitization.Thermodynamic modeling based on equilibrium mineral assemblages indicates that the rodingite of the Xialu Massif formed in an H_(2)O-saturated,CO_(2)-rich environment.The estimated conditions of metamorphism were-281-323℃and 0.4-3.9 kbar,representing the subgreenschist facies.In this environment,REEs and HFSEs were soluble in the fluids and partly removed.Moreover,these prehnite rodingites formed in a progressively reducing and less alkaline environment,as indicated by decreases in f(O_(2))and bulk-rock Fe^(3+)/Fe^(2+) ratios,and the records of fluidΔpH from the center to the margin of the studied rodingitized intrusion.展开更多
The Permian Chert Event is of great significance to understanding the geological evolution of the entire Permian; however,the origin of widespread chert formation is debated. We report new geochemical data from deep-m...The Permian Chert Event is of great significance to understanding the geological evolution of the entire Permian; however,the origin of widespread chert formation is debated. We report new geochemical data from deep-marine siliceous rocks of the upper Permian Da-long Formation, Lower Yangtze region, southeastern China. Their geochemical results show that these thin-bedded siliceous rocks have a clear biologic origin, with rare to no evidence of hydrothermal influence. The values of Al/(Al + Fe + Mn) and Eu/Eu~* are 0.60-0.84(mean = 0.72) and 0.45-1.08(mean = 0.77), respectively, and Mn/Ti ratios are relatively low(mean = 0.72). The correlations of LaN/CeN, LaN/YbN, and Fe203/Ti02 with Al_2 O_3/(Al_2 O_3 + Fe_2 O_3), along with the Ce anomaly, indicate that the Da-long siliceous rocks were deposited at a transitional zone between a continental margin and the open ocean; i.e., relatively close to terrestrial sediment input and far from hydrothermal activity. The accumulation of chert is related to its unique paleogeographic location in an equatorial setting with many submarine paleo-highlands.Intense upwelling and frequent local volcanism are the main factors that promoted the development of siliceous rocks in the studied area. Ocean acidification triggered by large-scale volcanism(Large Igneous Province) during the late Permian led to extensive silica precipitation and preservation.展开更多
Tonstein layers are found worldwide in the Permo-Carboniferous coal-bearing strata.This study investigates the geochronology,mineralogy,and geochemistry of four tonstein samples from the Permo-Carboniferous Benxi Form...Tonstein layers are found worldwide in the Permo-Carboniferous coal-bearing strata.This study investigates the geochronology,mineralogy,and geochemistry of four tonstein samples from the Permo-Carboniferous Benxi Formation,Ordos Basin,North China Craton(NCC).The typical features of the studied tonsteins include thin beds,lateral continuity,angular quartz grains,and euhedral zircons with similar U-Pb ages,indicating a significant pyroclastic origin.In addition,the tonstein samples have low TiO_(2)/Al_(2)O_(3)ratios(<0.02)and rare earth elements and yttrium(REY)concentrations with obvious negative Eu anomalies,indicating that the tonsteins have a felsic magma origin.Moreover,compared with the mean composition of clay shale,the studied tonsteins are characterized by high concentrations of the elements Nb and Ta,which may affect the concentration of the corresponding elements in surrounding coal seams.The zircon U-Pb ages of the tonsteins(293.9-298.8 Ma)provide a precise chronological framework on the Benxi Formation in the Ordos Basin,constraining the Gzhelian-Aselian stages.The tonsteins were probably sourced from arc volcanism along the western margin of the NCC during the early Permian,implying that the Alxa Terrane had not amalgamated with the NCC at that time.展开更多
The Xisha Block is a minor one in the South China Sea and an important tectonic unit in the northwestern part of the region.Zircon SHRIMP U-Pb ages for three volcanic intrusive core samples from Xike-1,an exploratory ...The Xisha Block is a minor one in the South China Sea and an important tectonic unit in the northwestern part of the region.Zircon SHRIMP U-Pb ages for three volcanic intrusive core samples from Xike-1,an exploratory well penetrating the bioherms of the Xisha Islands.The core samples are from the Miocene reef carbonate bedrock and are recognized as dark-gray biotite-hornblende gabbro,gray fne-grained biotite diorite,and gray fine-grained granite,respectively.Zircon cathodoluminescence (CL)images and trace Th,U and Pb compositions of the zircons show that these rocks are of volcanic intrusive origin.Zircon SHRIMP U-Pb dating yielded six groups of ages,ranging from 2451-1 857 Ma to early Cretaceous, which indicate that the formation and evolution of the Xisha Block was affected by the evolution and closure of Neotethys Ocean,probably within its eastern extension into South China Sea.Both old,deepsourced material,including fragments from Rodina supercontinent,and recent mantle-derived magma products contributed to the emergence and formation of the Xisha block.The SHRIMP U-Pb results also proved that this process differed from that of the Kontum massif,the Hainan Block,and the South China Block,but is similar to that of the Nansha and Zhongsha blocks.The process was associated with the effects of Yanshanian magmatism induced by subduction mechanisms of the Paleo-Pacific Plate or the reworking of the multiple magmatisms since the Early to mid-Yanshanian,possibly jointly experienced by the Xisha-Zhongsha-Nansha Block.展开更多
Ichnofossils are well developed in clastic rock reservoirs in marine and transitional facies, which can considerably change the physical properties of the reservoir. However, this influence is not well understood, rai...Ichnofossils are well developed in clastic rock reservoirs in marine and transitional facies, which can considerably change the physical properties of the reservoir. However, this influence is not well understood, raising an important problem in the effective development of petroleum reservoirs. This paper analyzes continental shelf margin delta reservoirs through core observation, cast thin section observation and reservoir physical property test. Some important scientific insights are obtained:(1) The presence of Cruziana ichnofacies, including Asterosoma, Ophiomorpha, Planolites, Skolithos, Thalassinoides, and other ichnofossils can be used to identify in subaqueous distributary channels, subaqueous levee, frontal sheet sand, abandoned river channels, crevasse channels, main channels and channel mouth bars. Considerable differences in the types of ichnofossils and the degree of bioturbation can be observed in the different petrofacies.(2) Ichnofossils and bioturbation play a complex role in controlling reservoir properties. The reservoir physical properties have the characteristics of a decrease–increase–decrease curve with increasing bioturbation degree. This complex change is controlled by the sediment mixing and packing of bioturbation and the diagenetic environment controlled by the ichnofossils.(3) Sea-level cycle changes affect the modification of the reservoir through sediment packing. Bioturbation weakens the reservoir's physical property when sea level slowly rises and improves the reservoir's physical property when base level slowly falls.展开更多
Several sets of Paleozoic tight reservoirs are developed in the Central Uplift of the South Yellow Sea Basin.A qualitative analysis of the microscopic pore structure of the tight reservoir rocks was carried out throug...Several sets of Paleozoic tight reservoirs are developed in the Central Uplift of the South Yellow Sea Basin.A qualitative analysis of the microscopic pore structure of the tight reservoir rocks was carried out through cast thin slice and scanning electron microscopic image observation.Based on reservoir pet-rophysical properties,thirty core samples in the Central Uplift of the South Yellow Sea Basin were selected for high-pressure mercury intrusion(HPMI)analysis,which was then combined with fractal calculation to classify and evaluate the tight reservoirs.The analysis of the HPMI curves and related parameters shows that the Paleozoic tight reservoirs can be divided into three types:Type-A,Type-B and Type-C.Type-A sandstone reservoirs contain pores with size mostly ranging between 0.01 and 0.1 mm,followed by pores with size range of 0.001-0.01 m m,and relatively fewer pores larger than 0.1 m m.The Type-B reservoirs are carbonate rocks with extremely heterogeneous pore size distribution,which is closely related to the development of dissolution pores and microfractures.Type-C sandstone reservoirs are dominated by nanopores and submicron pores that distribute more heterogeneously than pores in Type-A reservoirs.The pore distribution in sandstone reservoirs shows significant fractal characteristics and is closely related to the pore size.The heterogeneity of nanopore distribution has a negative cor-relation with porosity and median pressure and a relatively weak correlation with permeability.Our study has important implications for petroleum exploration in the South Yellow Sea Basin.展开更多
Biomineralization has garnered significant attention in the field of wastewater treatment due to its notable cost reduction compared to conventional methods.The reinjection water from oilfields containing an exceeding...Biomineralization has garnered significant attention in the field of wastewater treatment due to its notable cost reduction compared to conventional methods.The reinjection water from oilfields containing an exceedingly high concentration of calcium and ferric ions will pose amajor hazard in production.However,the utilization of biomineralization for precipitating these ions has been scarcely investigated due to limited tolerance among halophiles towards such extreme conditions.In this study,free and immobilized halophiles Virgibacillus dokdonensis were used to precipitate these ions and the effects were compared,at the same time,biomineralizationmechanisms and mineral characteristicswere further explored.The results showthat bacterial concentration and carbonic anhydrase activitywere higher when additionally adding ferric ion based on calcium ion;the content of protein,polysaccharides,deoxyribonucleic acid and humic substances in the extracellular polymers also increased compared to control.Calcium ions were biomineralized into calcite and vaterite with mul-tiple morphology.Due to iron doping,the crystallinity and thermal stability of calcium carbonate decreased,the content of O-C=O,N-C=OandC-O-PO_(3) increased,the stable carbon isotope values became much more negative,andβ-sheet in minerals disappeared.Higher calcium concentrations facilitated ferric ion precipitation,while ferric ions hindered calcium precipitation.The immobilized bacteria performed better in ferric ion removal,with a precipitation ratio exceeding 90%.Free bacteria performed better in calcium removal,and the precipitation ratio reached a maximum of 56%.This research maybe provides some reference for the co-removal of calcium and ferric ions from the oilfield wastewater.展开更多
Coastal regions are threatened by natural processes, such as erosion driven by storm surges and the effect of jetties, as well as by human behavior. The coastline of the Yellow River Delta(YRD) was monitored using the...Coastal regions are threatened by natural processes, such as erosion driven by storm surges and the effect of jetties, as well as by human behavior. The coastline of the Yellow River Delta(YRD) was monitored using the general high-tide line method, which combines Remote sensing(RS) and geographic information system(GIS) technology, using multi-spectral scanner(MSS), thematic mapper(TM), and enhanced thematic mapper plus(ETM+) images of the YRD from 1976 to 2014 as a data source. The results demonstrated that the shape and length of the YRD coastline has changed dramatically since 1976. The course of the Diaokouhe channel has resulted in mainly inland erosion in the north, and is primarily marine erosion; therefore, it was termed an erosion-type estuary. However, the coastline of the Qingshuigou course has moved seaward, demonstrating an accretion stage, and was therefore termed an accretion-type estuary. The coastline advanced forward before 1997 and shrank after 2003 in the southern part of the river mouth, which was due to the shift in the river mouth in 1996. It has continually extended outward in the northern part of the river mouth from 2003 onward. The coastline in the southern part of the river mouth has moved randomly, with the occurrence of both erosion and sedimentation caused by land reclamation and sea wave intrusion. In most cases, the coastline has extended offshore, especially in the northern part of the river mouth. The YRD coastline has changed frequently and rapidly from 1992 to 2014. The river mouth channel, river water and sediments, and precipitation were the major factors affecting the YRD. The YRD coastline was mainly in an accretion stage during flow periods. The erosion rate decreased and tended to be stable during a dry period. The coastline was basically stable when dry periods occurred over a long period. The location of Yellow River ports and sea erosion were the main factors driving coastline changes. The coastline was mainly influenced by the flow path of the Yellow River, with recent human activity also becoming a factor.展开更多
Calcium carbonate （CaCO3） crystals in their preferred orientation were obtained in BG11 culture media inoculated with Synechocystis sp. PCC6803 （inoculated BG11）. In this study, the features of calcium carbonate d...Calcium carbonate （CaCO3） crystals in their preferred orientation were obtained in BG11 culture media inoculated with Synechocystis sp. PCC6803 （inoculated BG11）. In this study, the features of calcium carbonate deposition were investigated. Inoculated BGll in different calcium ion concentrations was used for the experimental group, while the BGll culture medium was used for the control group. The surface morphologies of the calcium carbonate deposits in the experimental and control groups were determined by scanning and transmission electron microscopy. The deposits were analyzed by electronic probe micro-analysis, Fourier transform infrared spectrum, X-ray diffraction, thermal gravimetric analysis and differential scanning calorimetry. The results show that the surfaces of the crystals in the experimental group were hexahedral in a scaly pattern. The particle sizes were micrometer-sized and larger than those in the control group. The deposits of the control group contained calcium （Ca）, carbon （C）, oxygen （O）, phosphorus （P）, iron （Fe）, copper （Cu）, zinc （Zn）, and other elements. The deposits in the experimental group contained Ca, C, and O only. The deposits of both groups contained calcite. The thermal decomposition temperature of the deposits in the control group was lower than those in the experimental group. It showed that the CaCO3 deposits of the experimental group had higher thermal stability than those of the control group. This may be due to the secondary metabolites produced by the algae cells, which affect the carbonate crystal structure and result in a close-packed structure. The algae cells that remained after thermal weight loss were heavier in higher calcium concentrations in BGll culture media. There may be more calcium- containing crystals inside and outside of these cells. These results shall be beneficial for understanding the formation mechanism of carbonate minerals.展开更多
To investigate the influence of extractable organic matter （EOM） on pore evolution of lacustrine shales, Soxhlet extraction, using dichloromethane, was performed on a series of Chang 7 shale samples （Ordos Basin, C...To investigate the influence of extractable organic matter （EOM） on pore evolution of lacustrine shales, Soxhlet extraction, using dichloromethane, was performed on a series of Chang 7 shale samples （Ordos Basin, China） with vitrinite reflectance of 0.64% to 1.34%. Low-pressure gas adsorption experiments were conducted on the samples before and after extraction. The pore structure parameters were calculated from the gas adsorption data. The results show complex changes to the pore volumes and surface areas after extraction. The pore development of both the initial and extracted samples is strongly controlled by total organic carbon （TOC） content. Micropores developed mainly in organic matter （OM）, while mesopores and macropores predominantly developed in fractions other than OM. The influence of EOM on micropores is stronger than on mesopores and macropores. Organic solvents with a higher boiling point should be used to explore the effect of EOM on pore structure in the future.展开更多
The Yanchang Formation Chang 7 oil-bearing layer of the Ordos Basin is important in China for producing shale oil.The present-day in situ stress state is of practical implications for the exploration and development o...The Yanchang Formation Chang 7 oil-bearing layer of the Ordos Basin is important in China for producing shale oil.The present-day in situ stress state is of practical implications for the exploration and development of shale oil;however,few studies are focused on stress distributions within the Chang 7 reservoir.In this study,the present-day in situ stress distribution within the Chang 7 reservoir was predicted using the combined spring model based on well logs and measured stress data.The results indicate that stress magnitudes increase with burial depth within the Chang 7 reservoir.Overall,the horizontal maximum principal stress(SHmax),horizontal minimum principal stress(Shmin) and vertical stress(Sv) follow the relationship of Sv≥SHmax>Shmin,indicating a dominant normal faulting stress regime within the Chang 7 reservoir of Ordos Basin.Laterally,high stress values are mainly distributed in the northwestern parts of the studied region,while low stress values are found in the southeastern parts.Factors influencing stress distributions are also analyzed.Stress magnitudes within the Chang 7 reservoir show a positive linear relationship with burial depth.A larger value of Young's modulus results in higher stress magnitudes,and the differential horizontal stress becomes higher when the rock Young's modulus grows larger.展开更多
To establish the relationship among reservoir characteristics and rock physical parameters,we construct the well-bore rock physical models firstly,considering the influence factors,such as mineral composition,shale co...To establish the relationship among reservoir characteristics and rock physical parameters,we construct the well-bore rock physical models firstly,considering the influence factors,such as mineral composition,shale content,porosity,fluid type and saturation.Then with analyzing the change rules of elastic parameters along with the above influence factors and the cross-plots among elastic parameters,the sensitive elastic parameters of tight sandstone reservoir are determined,and the rock physics template of sweet spot is constructed to guide pre-stack seismic inversion.The results show that velocity ratio and Poisson impedance are the most sensitive elastic parameters to indicate the lithologic and gas-bearing properties of sweet spot in tight sandstone reservoir.The high-quality sweet spot is characterized by the lower velocity ratio and Poisson impedance.Finally,the actual seismic data are selected to predict the sweet spots in tight sandstone gas reservoirs,so as to verify the validity of the rock physical simulation results.The significant consistency between the relative logging curves and inversion results in different wells implies that the utilization of well-bore rock physical simulation can guide the prediction of sweet spot in tight sandstone gas reservoirs.展开更多
基金financially supported by the Natural Science Foundation of China(Grant Nos.42272104,42172094 and 41772076)。
文摘The Wangjiazhuang Cu(-Mo)deposit,located within the Zouping volcanic basin in western Shandong Province,China,is unique in this area for having an economic value.In order to expound the metallogenetic characteristics of this porphyry-like hydrothermal deposit,a detailed fluid inclusion study has been conducted,employing the techniques of representative sampling,fluid inclusion petrography,microthermometry,Raman spectroscopy,LA-ICP-MS analysis of single fluid inclusions,as well as cathode fluorescence spectrometer analysis of host mineral quartz.The deposit contains mainly two types of orebodies,i.e.veinlet-dissemination-stockwork orebodies in the K-Si alteration zone and pegmatiticquartz sulfide veins above them.In addition,minor breccia ore occurs locally.Four types of fluid inclusions in the deposit and altered quartz monzonite are identified:L-type one-or two-phase aqueous inclusions,V-type vapor-rich inclusions with V/L ratios greater than 50%-90%,D-type multiphase fluid inclusions containing daughter minerals or solids and S-type silicate-bearing fluid inclusions containing mainly muscovite and biotite.Ore petrography and fluid inclusion study has revealed a three-stage mineralization process,driven by magmatic-hydrothermal fluid activity,as follows.Initially,a hydrothermal fluid,separated from the parent magma,infiltrated into the quartz monzonite,resulting in its extensive K-Si alteration,as indicated by silicate-bearing fluid inclusions trapped in altered quartz monzonite.This is followed by the early mineralization,the formation of quartz veinlets and dissemination-stockwork ores.During the main mineralization stage,due to the participation and mixing of meteoric groundwater with magmatic-sourced hydrothermal fluid,the cooling and phase separation caused deposition of metals from the hydrothermal fluids.As a result,the pegmatitic-quartz sulfide-vein ores formed.In the late mineralization stage,decreasing fluid salinity led to the formation of L-type aqueous inclusions and chalcopyrite-sulfosalt ore.Coexistence of V-type and D-type inclusions and their similar homogenization temperatures with different homogenization modes suggest that phase separation or boiling of the ore-forming fluids took place during the early and the main mineralization stages.The formation P-T conditions of S-type inclusions and the early and the main mineralization stages were estimated as ca.156-182 MPa and 450-650℃,350-450℃,18-35 MPa and 280-380℃,8-15 MPa,respectively,based on the microthermometric data of the fluid inclusions formed at the individual stages.
基金supported by the National Basic Research Program of China (973 Program, No. 2014CB239001)
文摘The Ordos Basin is the largest petroliferous basin in China, where the Chang 7 Member shale serves as the major source rock in the basin, with an area of more than 100,000 km^2 So far, sedimentary and geochemical characterizations have rarely been conducted on the shale in shallow(< 1000 m) areas in the southeastern part of the basin, but such characterizations can help identify the genesis of organic-rich shale and promote the prediction and recovery of shale oil. In this paper,several outcrop sections of the Chang 7 Member in the Tongchuan area were observed and sampled, and sedimentary and geochemical characterizations were conducted for the well-outcropped YSC section. The study results show that the Chang7 Member shale is widely distributed laterally with variable thickness. The organic-rich shale is 7-25 m thick in total and exhibits obvious horizontal variation in mineral composition. In the eastern sections, the shale contains organic matter of TypeⅡ_2-Ⅲ and is low in thermal maturity, with high clay mineral content, low K-feldspar content, and no pyrite. In the western sections, the shale contains Type Ⅱ_1 organic matter and is low in thermal maturity, with high clay mineral, K-feldspar, and pyrite contents. The YSC section reveals three obvious intervals in vertical mineral composition and organic abundance.The Chang 7 Member organic-rich shale(TOC > 10%) contains mainly sapropelite and liptinite, with Type Ⅱ kerogen. It is generally characterized by a hydrocarbon potential of more than 70 mg/g, low maturity, and shallow-semideep lacustrine facies. In the western sections, the shale, still in a low maturity stage, has a higher hydrocarbon potential and is optional for shale oil recovery. However, the Chang 7 Member shale in the study area is highly heterogeneous and its shale oil recovery is practical only in the organic-rich intervals.
基金supported by the University Research Program of Shandong Province (Grant No.J09LE08)the Open Found of Key Laboratory of Depositional Mineralization & Sedimentary Mineral, Shandong Province (Grant No.DMSM200807)
文摘Abundant aromatic fractions were detected in oils from the Linnan subsag, including aphthalenes, phenanthrenes, triaromatic steroids, biphenyl, fluorenes, dibenzothiophenes, dibenzofuranes, as well as some typical higher plant-sourced compounds, such as pyrene, benzopyrene, fluoranthene, chryaene, benzofluoranthrene, perylene and cadalene. Occurrences of biomarkers indicate that oils from the Linnan subsag are typical terrestrially genetic oils. Developed in the depositional environment is a strong reduction condition typical of brackish-saline lake. Thermal evolution has entered into the mature-high mature stage.
基金financially supported by the National Key R&D Plan of China (Grant No. 2017YFC0601405)the National Natural Science Foundation of China (Grant No. 41772096)+1 种基金the Youth Innovation Team Development Plan of Universities in Shandong Province, the Shandong Province Key Research and Development Plan (Grant No. 2019GGX103021)the SDUST Research Fund (Grant No.2018TDJH101)
文摘Core samples from the deeply buried Ordovician Majiagou Formation below the Huainan Coalfield(E China) have been investigated for their carbonate types,major and trace elements(including rare earth elements) and C and O isotopes,The objective was to get a better insight into the possible occurrences of gas(and possibly oil) derived from Carboniferous coals.It was found that the carbonates are dolomites with strongly varying amounts of CaO and MgO.The low concentrations of SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3)indicate deposition in a normal marine environment with little terrigenous input,The Na_(2)O/K_(2)O,Fe/Mn and Sr/Ba ratios,as well as the Ga values indicate mainly a marine salinity and a hot and humid climate.The slight depletion of Ce and Eu,the depletion of heavy rare earth elements(HREE) and the enrichment of light rare earth elements(LREE) indicate deposition in a reducing environment.It thus appears that the Majiagou Formation below the Huainan Coalfield closely resembles that in the eastern part of the Ordos Basin,where several gas reservoirs are present,so that the Majiagou Formation under the Huainan Coalfield represents a promising target for hydrocarbon exploration.
基金supported by the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources (J1901-7,J1901-16)the Natural Foundation of Shandong Province (ZR2019QD002,ZR2017BD033)+6 种基金the Chinese Academy of Geological Sciences Fund (K1710)the National Key Research and Development Project of China (No.2016YFC0600310)the National Natural Science Foundation of China (NNSFCProject Nos.41672046,41641015,41703036,41720104009)the China Geological Survey (CGSProject No.DD20160023)the International Geological Correlation Programme (IGCP-649)
文摘The>2000 km Indus-Yarlung Tsangpo suture zone(IYSZ)is composed of the Neo-tethys oceanic remnants,flysch units and related continental rocks,which has been regarded as the boundary between the Eurasian and Indian terranes.Among the ophiolitic complexes,the Purang ophiolite is the biggest massif in the IYSZ,and many studies have been conducted on this ophiolite.However,previous studies have mainly focused on harzburgite,clinopyroxenite and dunite.Field observations show that mafic dykes were emplaced within the Purang ophiolite.However,petrogenetic evolutions of those mafic dykes are poorly understood.In this study,we present new LA-ICP-MS zircon U-Pb dating results,whole-rock geochemistry and Sr-Nd-Hf isotope analyses for microgabbro,gabbro and dolerite dykes from the Purang ophiolite of the southwestern IYSZ,respectively.Three samples yielded zircon U-Pb ages of144.2±2.1 Ma.127.9±2.3 Ma and 126.5±0.42 Ma,suggesting two different phases of magmatic activities distinctly.Whole-rock geochemical results suggest that the gabbro samples show alkaline features marked by enrichments of light rare earth elements(LREE)and large-ion lithophile elements(LILE),as well as Nb-Ta elements,suggesting an oceanic island basalt-like(OIB-like)geochemical affinity.However,the dolerite and microgabbro samples demonstrate sub-alkaline characteristics with normal mid-oceanic ridge basalt-like(N-MORB-like)geochemical features.Three distinct mafic dykes show significant Rb element depletion.The geochemical data and Sr-Nd-Hf isotopic features suggest that the microgabbro and gabbro rocks were derived from a depleted mantle that had been metasomatized by partial melts of sediments and enriched slab-derived fluids.The dolerite was also originated from a depleted mantle marked by significantly depleted Sr-Nd-Hf compositions,which was not influenced by enriched slab-derived fluids and sediments contamination during subsequent evolution.The isotope and geochemical data and tectonic diagrams suggest a tectonic transition from a within-plate to a midoceanic ridge basalt-like(MORB-like)setting during the period from ca.144 Ma to 127 Ma.Combined with regional background and this study,we propose that these mafic dykes were formed in an oceanic back-arc basin setting.Additionally,integrated with previous studies,we suggest that the geodynamic evolution of the southwestern and central parts of the Neo-Tethys oceanic basin is comparable in Early Cretaceous.
基金supported by the National Science and Technology Major Project(Grant No.2017ZX05035)
文摘The Upper Ordovician Wufeng-Lower Silurian Longmaxi and the Lower Cambrian Qiongzhusi shales are the major targets for shale gas exploration and development in China.Although the two organic-rich shales share similar distribution ranges and thicknesses,they exhibit substantially different exploration and development results.This work analyzed the nanopore structures of the shale reservoirs in this region.Pore development of 51 shale samples collected from various formations and locations was compared using the petromineralogical,geochemical,structural geological and reservoir geological methods.The results indicate that the reservoir space in these shales is dominated by organic pores and the total pore volume of micropores,mesopores,macropores in different tectonic areas and formations show different trends with the increase of TOC.It is suggested that organic pores of shale can be well preserved in areas with simple structure and suitable preservation conditions,and the shale with smaller maximum ancient burial depth and later hydrocarbongeneration-end-time is also more conducive to pore preservation.Organic pore evolution models are established,and they are as follows:①Organic matter pore development stage,②Early stage of organic matter pore destruction,and③late stage of organic matter pore destruction.The areas conducive to pore development are favorable for shale gas development.Research results can effectively guide the optimization and evaluation of favorable areas of shale gas.
基金supported by the Science Development Project of Shandong Province (No.2009GG20001021-07)the Open Fund of Shandong Provincial Key Laboratory of Depositional Mineralization & Sedimentary Minerals (No. DMSM200803)the SDUST Research Fund (No.2010KYTD103)
文摘It is becoming an important controlling factor of gas exploration and exploitation in the east part of Sulige gas field in the Ordos Basin where the reservoir of main gas formations is tight sandstones. Employing experimental methods of slice identification, casting slice, scan electron microscope, and X-ray diffrac- tions, we studied the characteristics of petrology and diagenesis on reservoirs in Shanl section of Shanxi formation and He8 section of Shihezi formation of the Permian system in the East II part of Sulige gas field. The results include： （1） the main sandstones in these areas are dominated by lithic sandstone and litbic silicarenite with low grade of maturity; （2） the diagenesis of sandstone in these areas mainly include compaction, cementation, corrosion and alteration. Conclusions are as follows： （1） the diagenetic stage reached period B of the middle diagenetic stage; （2） the early diagenetic compaction is one of the main factors to decreasing porosity; （3） the secondary pores formed by corrosion in acidity medium con- ditions in period A of the middle diagenetic stage can distinctly ameliorate the poor reservoir capability of sandstone and, （4） cementation in period B of the middle diagenetic stage is the most important factor leading; to poor physical property of sandstone reservoirs.
基金funded by National Natural Science Foundation of China (Grant No. U1663201, 41472099 and 41872155)the Strategic Priority Research Program of the Chinese Academy of Science (Grant No. XDA14010404)CNPC innovation Foundation (2016D-5007-0102)
文摘Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially for source rocks which have high-over level of thermal maturity. Systematic identification of original organism assemblages of the Lower Paleozoic potential source rocks and detailed carbon isotopic composition of kerogen analyses were conducted for four outcrop sections in the Tarim basin. Results indicated that the original organism assemblages of the lower part of the Lower Cambrian were composed mainly of benthic algae, whereas those of the Upper Cambrian and the Ordovician were characterized by planktonic algae. Kerogen carbon isotopic data demonstrated that the δ13 Ckerogen values of source rocks dominated by benthic algae are lower than-34‰, whereas the δ13 Ckerogen values of source rocks dominated by planktonic algae are higher than-30‰ in general. We tentatively suggested that the carbon species those are utilized by algae and the carbon isotopic fractionation during photosynthesis are the major controls for the δ13 Ckerogen values in the Lower Paleozoic source rocks in the Tarim basin. Correlating the δ13 C values of oils exploited in the Tarim basin, the original organism assemblages, and δ13 Ckerogen values of source rocks, it implied that the Lower Paleozoic oils exploited in the Tarim basin should be sourced from the source rocks with original organism assemblages dominated by planktonic algae, and the hydrocarbon sourced from the Cambrian benthic algae should be of great exploration potential in future. Original organism assemblages in source rocks can provide important clues for oil-source rocks correlation, especially for the source rocks with high thermal maturity.
基金supported by the National Natural Science Foundation of China(Grant No.41572044)the SGSTSP of the Chinese Academy of Sciences(Grant No.XDB03010201)+1 种基金SDUST Research Fund(Grant No.2015TDJH101)financial support from Chinese Scholarship Council(Grant No.201808370192)。
文摘The analysis of early stage rodingite from the ultramafic rocks of the Xialu Massif in the Xigaze Ophiolite,Tibet,in China shows that the rodingitization involved continuous changes in fluid composition during different stages of subduction.The early stage prehnite-bearing rodingite was produced at low pressures and temperatures along extensional fractures.Samples of rodingite were collected along a profile from the center to the margin of a rodingitized intrusive igneous rock(^10 m×30 m),and they record wide variations in bulk composition,mineralogy,and texture.The mineral assemblages,from center to margin,vary from(1)relics of primary clinopyroxene(Cpx_(r))and primary amphibole(Amp_(r))+newly formed late amphibole(Act)+primary plagioclase(Pl_(r))+clinozoisite+prehnite+albite+chlorite+titanite+ilmenite(R1 rodingite),through(2)relics of primary clinopyroxene(Cpx_(r))+newly formed late clinopyroxene(Cpx_(n))+primary and late amphiboles(Amp_(r)+Act)+clinozoisite+prehnite+albite+chlorite+titanite(R2 rodingite),to(3)newly formed late clinopyroxene(Cpx_(n))and amphibole(Act)+clinozoisite+prehnite+albite+chlorite+titanite(R3 rodingite).As a result of the metasomatic process of rodingitization,the content of CaO in the whole rock chemical composition from R1 to R3 increases,SiO_(2) decreases,and Na_(2)O+K_(2)O is almost completely removed.Massbalance diagrams show enrichments in large ion lithophile elements such as Rb,Cs,Ba,and Pb as well as Ni during rodingitization.The central part of the rodingitized intrusion(R1 rodingite)was only slightly affected by metasomatism.On the other hand,the contents of the rare earth elements(REEs),high field strength elements(HFSEs;e.g.Zr,Nb,Ta,Hf,and Y),and some highly compatible elements such as Cr and Sc decreased slightly during rodingitization.Thermodynamic modeling based on equilibrium mineral assemblages indicates that the rodingite of the Xialu Massif formed in an H_(2)O-saturated,CO_(2)-rich environment.The estimated conditions of metamorphism were-281-323℃and 0.4-3.9 kbar,representing the subgreenschist facies.In this environment,REEs and HFSEs were soluble in the fluids and partly removed.Moreover,these prehnite rodingites formed in a progressively reducing and less alkaline environment,as indicated by decreases in f(O_(2))and bulk-rock Fe^(3+)/Fe^(2+) ratios,and the records of fluidΔpH from the center to the margin of the studied rodingitized intrusion.
基金supported by the National Natural Science Foundation of China (Grant No. 41702129)Chongqing Research Program of Basic Research and Frontier Technology (Grant No. cstc2017jcyjAX0448)+3 种基金Open Fund of Key Laboratory of Sedimentary Basin and Oil and Gas Resources, Ministry of Land and Resources (Chengdu Center, CGS) (Grant No. CDCGS2018003)State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (Grant No. 173115)the Science and Technology Research Program of Chongqing Municipal Education Commission (Grant No. KJQN201800115)Fundamental Research Funds for the Central Universities (Grant No. 106112017CDJXY240001)
文摘The Permian Chert Event is of great significance to understanding the geological evolution of the entire Permian; however,the origin of widespread chert formation is debated. We report new geochemical data from deep-marine siliceous rocks of the upper Permian Da-long Formation, Lower Yangtze region, southeastern China. Their geochemical results show that these thin-bedded siliceous rocks have a clear biologic origin, with rare to no evidence of hydrothermal influence. The values of Al/(Al + Fe + Mn) and Eu/Eu~* are 0.60-0.84(mean = 0.72) and 0.45-1.08(mean = 0.77), respectively, and Mn/Ti ratios are relatively low(mean = 0.72). The correlations of LaN/CeN, LaN/YbN, and Fe203/Ti02 with Al_2 O_3/(Al_2 O_3 + Fe_2 O_3), along with the Ce anomaly, indicate that the Da-long siliceous rocks were deposited at a transitional zone between a continental margin and the open ocean; i.e., relatively close to terrestrial sediment input and far from hydrothermal activity. The accumulation of chert is related to its unique paleogeographic location in an equatorial setting with many submarine paleo-highlands.Intense upwelling and frequent local volcanism are the main factors that promoted the development of siliceous rocks in the studied area. Ocean acidification triggered by large-scale volcanism(Large Igneous Province) during the late Permian led to extensive silica precipitation and preservation.
基金supported by the National Natural Science Foundation of China(Grant Nos.41972170,42102127)Shandong Provincial Natural Science Foundation(Grant No.ZR2021QD087)+1 种基金Chinese Postdoctoral Science Foundation(Grant No.2021M702019)SDUST Research Fund(Grant No.2018TDJH101)。
文摘Tonstein layers are found worldwide in the Permo-Carboniferous coal-bearing strata.This study investigates the geochronology,mineralogy,and geochemistry of four tonstein samples from the Permo-Carboniferous Benxi Formation,Ordos Basin,North China Craton(NCC).The typical features of the studied tonsteins include thin beds,lateral continuity,angular quartz grains,and euhedral zircons with similar U-Pb ages,indicating a significant pyroclastic origin.In addition,the tonstein samples have low TiO_(2)/Al_(2)O_(3)ratios(<0.02)and rare earth elements and yttrium(REY)concentrations with obvious negative Eu anomalies,indicating that the tonsteins have a felsic magma origin.Moreover,compared with the mean composition of clay shale,the studied tonsteins are characterized by high concentrations of the elements Nb and Ta,which may affect the concentration of the corresponding elements in surrounding coal seams.The zircon U-Pb ages of the tonsteins(293.9-298.8 Ma)provide a precise chronological framework on the Benxi Formation in the Ordos Basin,constraining the Gzhelian-Aselian stages.The tonsteins were probably sourced from arc volcanism along the western margin of the NCC during the early Permian,implying that the Alxa Terrane had not amalgamated with the NCC at that time.
文摘The Xisha Block is a minor one in the South China Sea and an important tectonic unit in the northwestern part of the region.Zircon SHRIMP U-Pb ages for three volcanic intrusive core samples from Xike-1,an exploratory well penetrating the bioherms of the Xisha Islands.The core samples are from the Miocene reef carbonate bedrock and are recognized as dark-gray biotite-hornblende gabbro,gray fne-grained biotite diorite,and gray fine-grained granite,respectively.Zircon cathodoluminescence (CL)images and trace Th,U and Pb compositions of the zircons show that these rocks are of volcanic intrusive origin.Zircon SHRIMP U-Pb dating yielded six groups of ages,ranging from 2451-1 857 Ma to early Cretaceous, which indicate that the formation and evolution of the Xisha Block was affected by the evolution and closure of Neotethys Ocean,probably within its eastern extension into South China Sea.Both old,deepsourced material,including fragments from Rodina supercontinent,and recent mantle-derived magma products contributed to the emergence and formation of the Xisha block.The SHRIMP U-Pb results also proved that this process differed from that of the Kontum massif,the Hainan Block,and the South China Block,but is similar to that of the Nansha and Zhongsha blocks.The process was associated with the effects of Yanshanian magmatism induced by subduction mechanisms of the Paleo-Pacific Plate or the reworking of the multiple magmatisms since the Early to mid-Yanshanian,possibly jointly experienced by the Xisha-Zhongsha-Nansha Block.
基金The National Natural Science Foundation of China under contract Nos 41872112 and 42077410the Key Research Project of Higher Education Institutions in Henan University under contract No. 20A170010+1 种基金the Program for Innovative Research Team (in Science and Technology) of Henan Polytechnic University under contract No. T2022-05the Foundation of Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Mineral under contract No. DMSM2018027。
文摘Ichnofossils are well developed in clastic rock reservoirs in marine and transitional facies, which can considerably change the physical properties of the reservoir. However, this influence is not well understood, raising an important problem in the effective development of petroleum reservoirs. This paper analyzes continental shelf margin delta reservoirs through core observation, cast thin section observation and reservoir physical property test. Some important scientific insights are obtained:(1) The presence of Cruziana ichnofacies, including Asterosoma, Ophiomorpha, Planolites, Skolithos, Thalassinoides, and other ichnofossils can be used to identify in subaqueous distributary channels, subaqueous levee, frontal sheet sand, abandoned river channels, crevasse channels, main channels and channel mouth bars. Considerable differences in the types of ichnofossils and the degree of bioturbation can be observed in the different petrofacies.(2) Ichnofossils and bioturbation play a complex role in controlling reservoir properties. The reservoir physical properties have the characteristics of a decrease–increase–decrease curve with increasing bioturbation degree. This complex change is controlled by the sediment mixing and packing of bioturbation and the diagenetic environment controlled by the ichnofossils.(3) Sea-level cycle changes affect the modification of the reservoir through sediment packing. Bioturbation weakens the reservoir's physical property when sea level slowly rises and improves the reservoir's physical property when base level slowly falls.
基金This study is supported by the National Natural Science Foun-dation of China(41806057)the Shandong Provincial Natural Science Foundation,China(ZR2018BD026).
文摘Several sets of Paleozoic tight reservoirs are developed in the Central Uplift of the South Yellow Sea Basin.A qualitative analysis of the microscopic pore structure of the tight reservoir rocks was carried out through cast thin slice and scanning electron microscopic image observation.Based on reservoir pet-rophysical properties,thirty core samples in the Central Uplift of the South Yellow Sea Basin were selected for high-pressure mercury intrusion(HPMI)analysis,which was then combined with fractal calculation to classify and evaluate the tight reservoirs.The analysis of the HPMI curves and related parameters shows that the Paleozoic tight reservoirs can be divided into three types:Type-A,Type-B and Type-C.Type-A sandstone reservoirs contain pores with size mostly ranging between 0.01 and 0.1 mm,followed by pores with size range of 0.001-0.01 m m,and relatively fewer pores larger than 0.1 m m.The Type-B reservoirs are carbonate rocks with extremely heterogeneous pore size distribution,which is closely related to the development of dissolution pores and microfractures.Type-C sandstone reservoirs are dominated by nanopores and submicron pores that distribute more heterogeneously than pores in Type-A reservoirs.The pore distribution in sandstone reservoirs shows significant fractal characteristics and is closely related to the pore size.The heterogeneity of nanopore distribution has a negative cor-relation with porosity and median pressure and a relatively weak correlation with permeability.Our study has important implications for petroleum exploration in the South Yellow Sea Basin.
基金supported by the National Natural Science Foundation of China(Nos.42072136,41972108,and 42106144)the Natural Science Foundation of Shandong Province(Nos.ZR2023MD063,ZR2020MC041,and ZR2020QD089)+1 种基金the Key Laboratory of Marine Biogenetic Resources,Third Institute of Oceanography,Ministry of Natural Resources(No.SKDZK20230127)the Foreign visiting scholar funded by Shandong Provincial government.
文摘Biomineralization has garnered significant attention in the field of wastewater treatment due to its notable cost reduction compared to conventional methods.The reinjection water from oilfields containing an exceedingly high concentration of calcium and ferric ions will pose amajor hazard in production.However,the utilization of biomineralization for precipitating these ions has been scarcely investigated due to limited tolerance among halophiles towards such extreme conditions.In this study,free and immobilized halophiles Virgibacillus dokdonensis were used to precipitate these ions and the effects were compared,at the same time,biomineralizationmechanisms and mineral characteristicswere further explored.The results showthat bacterial concentration and carbonic anhydrase activitywere higher when additionally adding ferric ion based on calcium ion;the content of protein,polysaccharides,deoxyribonucleic acid and humic substances in the extracellular polymers also increased compared to control.Calcium ions were biomineralized into calcite and vaterite with mul-tiple morphology.Due to iron doping,the crystallinity and thermal stability of calcium carbonate decreased,the content of O-C=O,N-C=OandC-O-PO_(3) increased,the stable carbon isotope values became much more negative,andβ-sheet in minerals disappeared.Higher calcium concentrations facilitated ferric ion precipitation,while ferric ions hindered calcium precipitation.The immobilized bacteria performed better in ferric ion removal,with a precipitation ratio exceeding 90%.Free bacteria performed better in calcium removal,and the precipitation ratio reached a maximum of 56%.This research maybe provides some reference for the co-removal of calcium and ferric ions from the oilfield wastewater.
基金Under the auspices of National Natural Science Foundation of China(No.41602356)China Postdoctoral Science Foundation(No.2017M622240)+2 种基金Key Research and Development Plan of Shandong Province(No.GG201712050002)Geological Exploration Fund of Shandong Province(No.2013(55),2016(7))Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals Open Fund(No.DMSM2018024)
文摘Coastal regions are threatened by natural processes, such as erosion driven by storm surges and the effect of jetties, as well as by human behavior. The coastline of the Yellow River Delta(YRD) was monitored using the general high-tide line method, which combines Remote sensing(RS) and geographic information system(GIS) technology, using multi-spectral scanner(MSS), thematic mapper(TM), and enhanced thematic mapper plus(ETM+) images of the YRD from 1976 to 2014 as a data source. The results demonstrated that the shape and length of the YRD coastline has changed dramatically since 1976. The course of the Diaokouhe channel has resulted in mainly inland erosion in the north, and is primarily marine erosion; therefore, it was termed an erosion-type estuary. However, the coastline of the Qingshuigou course has moved seaward, demonstrating an accretion stage, and was therefore termed an accretion-type estuary. The coastline advanced forward before 1997 and shrank after 2003 in the southern part of the river mouth, which was due to the shift in the river mouth in 1996. It has continually extended outward in the northern part of the river mouth from 2003 onward. The coastline in the southern part of the river mouth has moved randomly, with the occurrence of both erosion and sedimentation caused by land reclamation and sea wave intrusion. In most cases, the coastline has extended offshore, especially in the northern part of the river mouth. The YRD coastline has changed frequently and rapidly from 1992 to 2014. The river mouth channel, river water and sediments, and precipitation were the major factors affecting the YRD. The YRD coastline was mainly in an accretion stage during flow periods. The erosion rate decreased and tended to be stable during a dry period. The coastline was basically stable when dry periods occurred over a long period. The location of Yellow River ports and sea erosion were the main factors driving coastline changes. The coastline was mainly influenced by the flow path of the Yellow River, with recent human activity also becoming a factor.
基金Supported by the National Natural Science Foundation of China(Nos.40972043,41040018,41210104058,21176145,41372108,41302079)the Higher Educational Science and Technology Program of Shandong Province(No.J10LC15)+4 种基金the China Postdoctoral Science Foundation(No.2013M540560)the Program for Scientific Research Innovation Team in Colleges and Universities of Shandong Province,and SDUST Research Fund(No.2010KYTD103)the Open Project of Key Lab of Marine Bioactive Substance and Modern Analytical Technique,State Oceanic Administration,China(No.MBSMAT-2012-03)the Scientific and Technological Program of Qingdao(No.13-1-4-232-jch)the Domestic Visiting Scholar Program for Young Core Teachers in Shandong Universities,Shandong Province,China
文摘Calcium carbonate （CaCO3） crystals in their preferred orientation were obtained in BG11 culture media inoculated with Synechocystis sp. PCC6803 （inoculated BG11）. In this study, the features of calcium carbonate deposition were investigated. Inoculated BGll in different calcium ion concentrations was used for the experimental group, while the BGll culture medium was used for the control group. The surface morphologies of the calcium carbonate deposits in the experimental and control groups were determined by scanning and transmission electron microscopy. The deposits were analyzed by electronic probe micro-analysis, Fourier transform infrared spectrum, X-ray diffraction, thermal gravimetric analysis and differential scanning calorimetry. The results show that the surfaces of the crystals in the experimental group were hexahedral in a scaly pattern. The particle sizes were micrometer-sized and larger than those in the control group. The deposits of the control group contained calcium （Ca）, carbon （C）, oxygen （O）, phosphorus （P）, iron （Fe）, copper （Cu）, zinc （Zn）, and other elements. The deposits in the experimental group contained Ca, C, and O only. The deposits of both groups contained calcite. The thermal decomposition temperature of the deposits in the control group was lower than those in the experimental group. It showed that the CaCO3 deposits of the experimental group had higher thermal stability than those of the control group. This may be due to the secondary metabolites produced by the algae cells, which affect the carbonate crystal structure and result in a close-packed structure. The algae cells that remained after thermal weight loss were heavier in higher calcium concentrations in BGll culture media. There may be more calcium- containing crystals inside and outside of these cells. These results shall be beneficial for understanding the formation mechanism of carbonate minerals.
基金funded by the National Science Foundation of China(41502144,41503034)the Foundation of the State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing(No.PRP/open-1612)+2 种基金the Fund of the Education Department of Sichuan Province(16ZA0075)the Youth Scientific Innovation Team of Hydrocarbon Accumulation and Geochemistry,Southwest Petroleum University(2015CXTD02)the Sichuan Province University Scientific Innovation Team Construction Project(USITCP)
文摘To investigate the influence of extractable organic matter （EOM） on pore evolution of lacustrine shales, Soxhlet extraction, using dichloromethane, was performed on a series of Chang 7 shale samples （Ordos Basin, China） with vitrinite reflectance of 0.64% to 1.34%. Low-pressure gas adsorption experiments were conducted on the samples before and after extraction. The pore structure parameters were calculated from the gas adsorption data. The results show complex changes to the pore volumes and surface areas after extraction. The pore development of both the initial and extracted samples is strongly controlled by total organic carbon （TOC） content. Micropores developed mainly in organic matter （OM）, while mesopores and macropores predominantly developed in fractions other than OM. The influence of EOM on micropores is stronger than on mesopores and macropores. Organic solvents with a higher boiling point should be used to explore the effect of EOM on pore structure in the future.
基金financial supports are from the National Natural Science Foundation of China (41702130 and 41971335)China Postdoctoral Science Foundation (2017T100419 and 2019M660269)Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)。
文摘The Yanchang Formation Chang 7 oil-bearing layer of the Ordos Basin is important in China for producing shale oil.The present-day in situ stress state is of practical implications for the exploration and development of shale oil;however,few studies are focused on stress distributions within the Chang 7 reservoir.In this study,the present-day in situ stress distribution within the Chang 7 reservoir was predicted using the combined spring model based on well logs and measured stress data.The results indicate that stress magnitudes increase with burial depth within the Chang 7 reservoir.Overall,the horizontal maximum principal stress(SHmax),horizontal minimum principal stress(Shmin) and vertical stress(Sv) follow the relationship of Sv≥SHmax>Shmin,indicating a dominant normal faulting stress regime within the Chang 7 reservoir of Ordos Basin.Laterally,high stress values are mainly distributed in the northwestern parts of the studied region,while low stress values are found in the southeastern parts.Factors influencing stress distributions are also analyzed.Stress magnitudes within the Chang 7 reservoir show a positive linear relationship with burial depth.A larger value of Young's modulus results in higher stress magnitudes,and the differential horizontal stress becomes higher when the rock Young's modulus grows larger.
基金supported by the National Key R&D Program of China(Grant No.2018YFC1405900)the Major Projects of National Science and Technology(Grant Nos.2016ZX05011-002,2016ZX05027-002-005)+3 种基金the National Natural Science Foundation of China(Grant No.41806073)the Natural Science Foundation of Shandong Province(Grant No.ZR2017BD014)Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals,Shandong University of Science and Technology(Grant No.DMSM2017042)the Fundamental Research Funds for the Central Universities(Grant No.201964016)
文摘To establish the relationship among reservoir characteristics and rock physical parameters,we construct the well-bore rock physical models firstly,considering the influence factors,such as mineral composition,shale content,porosity,fluid type and saturation.Then with analyzing the change rules of elastic parameters along with the above influence factors and the cross-plots among elastic parameters,the sensitive elastic parameters of tight sandstone reservoir are determined,and the rock physics template of sweet spot is constructed to guide pre-stack seismic inversion.The results show that velocity ratio and Poisson impedance are the most sensitive elastic parameters to indicate the lithologic and gas-bearing properties of sweet spot in tight sandstone reservoir.The high-quality sweet spot is characterized by the lower velocity ratio and Poisson impedance.Finally,the actual seismic data are selected to predict the sweet spots in tight sandstone gas reservoirs,so as to verify the validity of the rock physical simulation results.The significant consistency between the relative logging curves and inversion results in different wells implies that the utilization of well-bore rock physical simulation can guide the prediction of sweet spot in tight sandstone gas reservoirs.
