Based on the data of field outcrops,drilling cores,casting thin sections,well logging interpretation,oil/gas shows during drilling,and oil/gas testing results,and combined with modern salt-lake sediments in the Qingha...Based on the data of field outcrops,drilling cores,casting thin sections,well logging interpretation,oil/gas shows during drilling,and oil/gas testing results,and combined with modern salt-lake sediments in the Qinghai Lake,the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics,development patterns,sand control factors,and hydrocarbon accumulation characteristics.Beach-bar sand bodies are widely developed in the Neogene saline lake basin,and they are lithologically fine sandstone and siltstone,with wavy bedding,low-angle cross bedding,and lenticular-vein bedding.In view of spatial-temporal distribution,the beach-bar sand bodies are stacked in multiple stages vertically,migratory laterally,and extensive and continuous in NW-SE trending pattern in the plane.The stacking area of the Neogene beach-bar sandstone is predicted to be 3000 km^(2).The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone,and the debris input from the source area affects the scale and enrichment of beach-bar sandstone.The ancient landform controls the morphology and stacking style of beach-bar sandstone,and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone.The beach-bars have a reservoir-forming feature of“one reservoir in one sand body”,with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction.Three favorable exploration target zones in Zhahaquan,Yingdong-eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements.展开更多
Chinese Neogene Rhinocerotidae has quite a complete record and its temporal range is the Early Miocene to Late Pliocene. The samples include 25 species in 4 tribes of 2 subfamilies. They are used as a foundation for t...Chinese Neogene Rhinocerotidae has quite a complete record and its temporal range is the Early Miocene to Late Pliocene. The samples include 25 species in 4 tribes of 2 subfamilies. They are used as a foundation for the study of the evolution of the family and its relation to climatic changes. Taxonomic diversity, new records and extinctions are estimated for each Chinese Neogene mammal faunal unit (NMU). The diversity of Chinese Rhinocerotidae varies noticeably throughout the Neogene and is recognized within five stages: the Middle Miocene and Late Miocene are stages of high diversity and the Early Miocene, early Late Miocene and Pliocene are stages of low diversity. Rhinocerotid diversity and morphology are closely related to environmental factors and particularly sensitive to changes in ambient temperature and humidity. The interpretation of climatic variation reflected in the evolution of Rhinocerotidae corresponds precisely with the conclusions drawn from other workers and provides new evidence for research on the Neogene terrestrial ecosystem in China.展开更多
Core, well logging and seismic data were used to investigate sandbody architectural characteristics within Lower Member of Minghuazhen Formation in Neogene, Bohai BZ25 Oilfield, and to analyze the sedimentary microfac...Core, well logging and seismic data were used to investigate sandbody architectural characteristics within Lower Member of Minghuazhen Formation in Neogene, Bohai BZ25 Oilfield, and to analyze the sedimentary microfacies, distribution and internal architecture characteristics of the bar finger within shoal water delta front. The branched sand body within shoal water delta front is the bar finger, consisting of the mouth bar, distributary channel over bar, and levee. The distributary channel cuts through the mouth bar, and the thin levee covers the mouth bar which is located at both sides of distributary channel. The bar finger is commonly sinuous and its sinuosity increases basinward. The distributary channel changes from deeply incising the mouth bar to shallowly incising top of the mouth bar.The aspect ratio ranges from 25 to 50 and there is a double logarithmic linear positive relationship between the width and thickness for the bar finger, which is controlled by base-level changing in study area. For the bar finger, injection and production in the same distributary channel should be avoided during water flooding development. In addition, middle–upper distributary channel and undrilled mouth bar are focus of tapping remaining oil.展开更多
The west block of the middle belt of TanLu fault belt is one of the areas where volcanic landforms are mainly distributed. This paper divides the volcanic landforms into four grades according to formation, morphology,...The west block of the middle belt of TanLu fault belt is one of the areas where volcanic landforms are mainly distributed. This paper divides the volcanic landforms into four grades according to formation, morphology, and ingredient of matter. Lava cones are divided into two types based on the force of top-support and the fluid form of magma: the arc-projecting type and spring-spilling type. Furthermore, the courses of development of volcanic landforms are divided into three stages according to the form and strength of volcanic activities.展开更多
Sandstones from the Neogene Siwalik successions of the East and West Siang Districts of Arunachal Pradesh were analyzed to evaluate source-area weathering,provenance,and tectonic setting by using major,trace,and rare ...Sandstones from the Neogene Siwalik successions of the East and West Siang Districts of Arunachal Pradesh were analyzed to evaluate source-area weathering,provenance,and tectonic setting by using major,trace,and rare earth elements(REEs)as proxies.The sandstones are classified as lithic arenite and wacke arenite based on their mineralogical compositions.The values of different weathering indices such as Chemical Index of Alteration(CIA;60.93–89.86)and Chemical Index of Weathering(CIW;40–96.8)suggest moderate to intense weathering in the source area.The plot of Th/Sc versus Zr/Sc indicates enrichment of zircon by sediment sorting and/or recycling from a weathered source.The high positive correlation between Al2 O_(3) and K2 O points towards a strong influence of the constituent clay minerals on the major oxide composition of the sandstones.Petrographic analysis together with enriched LREE,flat HREE,negative Eu anomalies(Eu/Eu^(*)=0.47 to 0.90)in the chondrite-normalized diagrams,and the ratios of La/Sc,La/Co,Th/Sc,Th/Co,Cr/Th collectively suggests that the Neogene sediments were derived from felsic igneous and/or reworked sedimentary/metasedimentary sources in an upper continental crustal setting.The geochemical characteristics of the studied Neogene Siwalik sandstones indicate that the sediments were sourced from pre-Himalayan gneisses and granitoids together with metabasic rocks,which had formed in a passive margin tectonic setup.展开更多
The Neogene Terror Rift in the Antarctic Victoria Land Basin(VLB)of the Ross Sea,Antarctica,is composed of the Discovery Graben and the Lee Arch.Many Neogene volcanoes are aligned in the north-south direction in the s...The Neogene Terror Rift in the Antarctic Victoria Land Basin(VLB)of the Ross Sea,Antarctica,is composed of the Discovery Graben and the Lee Arch.Many Neogene volcanoes are aligned in the north-south direction in the southern VLB,belonging to the McMurdo Volcanic Group.However,due to multiple glaciations and limited seismic data,the volcanic processes are still unclear in the northern VLB,especially in the Terror Rift.Multichannel seismic profiles were collected at the VLB from the 32nd Chinese National Antarctic Research Expedition(CHINARE).We utilized four seismic profiles from the CHINARE and additional historical profiles,along with gravity and magnetic anomalies,to analyze faults and stratigraphic characteristics in the northern Terror Rift and volcanism in the VLB.Negative flower structures found in the northern Terror Rift suggest that the Terror Rift was affected by dextral strike-slip faults extending from the northern Victoria Land(NVL).After the initial orthogonal tension,the rift transited into an oblique extension,forming a set of downward concaving normal faults and accommodation zones in the Terror Rift.On the Lee Arch,several imbricated normal faults formed and converged into a detachment fault.Under gravitational forces,the strata bent upward and formed a rollover anticline.Many deep faults and thin strata subjected to erosion facilitated volcanic activity.A brittle volcanic region in the VLB was affected by dextral strike-slip movements and east-west extension,resulting in two Neogene volcanic chains that connect three igneous provinces in the VLB:the Hallett,Melbourne,and Erebus Provinces.These two chains contain mud volcanoes with magnetic nuclei,volcanic intrusions,and late-stage volcanic eruptions.Volcanisms have brought about opposite polarities of magnetic anomalies in Antarctica,indicating the occurrence of multiple volcanic activities.展开更多
By using drilling,high-precision 3 D seismic data,data of geochemistry,logging and testing,the reservoir characteristics and accumulation conditions of the KL6-1 lithologic oilfield in the Laibei Low Uplift in the Boh...By using drilling,high-precision 3 D seismic data,data of geochemistry,logging and testing,the reservoir characteristics and accumulation conditions of the KL6-1 lithologic oilfield in the Laibei Low Uplift in the Bohai Sea are examined comprehensively.The study shows that:KL6-1 oilfield is a monolithic,high-quality,large-scale Neogene lithologic oilfield featuring shallow reservoir depth,high productivity,concentrated oil-bearing intervals,large oil-bearing area,and high reserve abundance;hydrocarbon source supply from two directions provides a sufficient material basis for the formation of large oil field;two types of"inherited structural ridge"developed under the effect of block rotation,late active faults formed by Neotectonic movement,and widely distributed contiguous sand bodies provide an efficient oil and gas transportation system for the large-scale accumulation of oil and gas;contiguous channel and lacustrine lowstand system sand bodies developed in low accommodation condition provide the basic condition for the formation of large-scale lithologic traps;deep formations structural ridge,faults(dominant migration pathways)and large-scale superimposed contiguous sand bodies constitute a"vine type"oil and gas migration and accumulation system in the Laibei Low Uplift,which is conducive to the formation of large-scale and high-abundance lithologic reservoir in this area.The successful discovery of KL6-1,100 million ton reserve order lithologic oil field,has revealed the exploration potential of Neogene large lithologic reservoirs in Bohai Sea,expanded the exploration field,and also has certain reference significance for the exploration of large lithologic reservoirs in similar areas.展开更多
Geochemical analysis of Neogene mudrocks from Sitakund anticline, Chittagong Tripura Fold Belt (CTFB), Bengal Basin, Bangladesh, was deployed to delineate the provenance, tectonics and depositional environments. Repre...Geochemical analysis of Neogene mudrocks from Sitakund anticline, Chittagong Tripura Fold Belt (CTFB), Bengal Basin, Bangladesh, was deployed to delineate the provenance, tectonics and depositional environments. Representative samples went through mineralogical and geochemical analysis concerning major, trace and rare earth element analysis. Rigaku ZSX Primus and NITON XL3t 800 XRF instruments were utilized for the determination of major and trace elements. The experiment results reveal that the Neogene mudrocks are rich in silica having concentration of 58.10% to 62.60% with an average of 59.90%. Therefore, the geochemical response from the experiments apparently proved the existence of the active continental margin setting for the Neogene mudrocks. Different concentrations and ratios of major oxides satisfy that the mudrocks were derived from felsic source rocks. In addition, chemical index of alteration (CIA) values for the Neogene mudrocks vary from 67.81 to 77.57 with an average 74.41 indicating significant weathering at the source areas. Moreover, U/Th, Cu/Zn, Ni/Co and V/Cr ratios designate that the mudrocks were deposited in oxidizing depositional environment.展开更多
The remarkable uplift of the Tibetan Plateau in the Neogene had great impacts on the climate and environment of East Asia and even the world.Therefore,establishment of the Neogene stratigraphic framework of the Tibeta...The remarkable uplift of the Tibetan Plateau in the Neogene had great impacts on the climate and environment of East Asia and even the world.Therefore,establishment of the Neogene stratigraphic framework of the Tibetan Plateau is of great significance to research in various fields of geosciences.Based on marine sediments,the international chronostratigraphic system of the Neogene is divided into six stages in the Miocene and two stages in the Pliocene.Since the beginning of the Cenozoic,the share of terrestrial strata on continents has increased rapidly.By the Neogene,it had far exceeded that of marine strata,and almost all deposits on the Tibetan Plateau and its surrounding areas were terrestrial strata.In China,the Miocene includes five stages and the Pliocene includes two stages.Except for the Tunggurian of the Miocene,which has a lower boundary at 15 Ma,the other stages have the same paleomagnetic definitions and time intervals as the corresponding international marine stages.Mammalian fossils play a very important role in the division and correlation of Cenozoic terrestrial strata,and rodent,carnivore,proboscidean,perissodactyl and artiodactyl fossils are especially important in Neogene terrestrial biostratigraphy.There are many basins with well-exposed strata and abundant mammalian fossils in the Tibetan Plateau.The lower boundary stratotype sections of the Neogene Xiejian and Bahean stages are located respectively in the Xining and Linxia basins,and there are precise paleomagnetic dates in coordination with mammalian fossils.The lower boundary stratotypes of other stages can also be effectively determined in the Tibetan Plateau.Many first appearing mammalian genera in East Asia also appeared in the Tibetan Plateau and its surrounding areas,especially in the Linxia Basin on the northeast margin and in the Siwaliks on the southwest margin.Among them,Prodeinotherium first appeared at the bottom of the Miocene in the Siwaliks,and the earliest Hipparion of the Old World first appeared at the bottom of the Bahean Stage in the Linxia Basin.Carbon and oxygen isotope analysis of enamel and paleosols of Cenozoic sediments and mammal fossils in the Tibetan Plateau and its surrounding areas have been used to reconstruct the climate,environment and vegetation development characteristics,and revealed that these changes were not only related to global change,but also had regional features.Evidence of the Late Miocene C4plant expansion event based on carbon isotope changes comes from the southern margin of the Tibetan Plateau,but in sharp contrast,δ13C indicates that there was still no clear or significant C4plant signal on the northern margin of the Tibetan Plateau until the end of the Neogene.Theδ18O analysis shows that there were several major climate change events in the Cenozoic,especially in the Late Miocene at about 7 Ma,when positive drift ofδ18O indicates that the northern and southern sides of the Tibetan Plateau were changing to drier environments.The strong uplift of the Tibetan Plateau in the Late Miocene strengthened the thermal contrast between sea and land,which strengthened monsoon circulation and led to the expansion of C4vegetation in South Asia.However,the East Asian summer monsoon,which can bring atmospheric precipitation and a climate suitable for C4plants to northern China,was not enough to affect the northern Tibetan Plateau.The Tibetan Plateau on the whole rose to an altitude of about 3000 m in the Miocene,becoming a barrier to mammalian migration;it reached its modern altitude of more than 4000 m in the Pliocene,thus forming a cryosphere environment,which led to the emergence of ancestral types of the Ice Age fauna.展开更多
The Neogene is an important period for studying the onset of subduction,with numerous subduction zones forming in the western Pacific,including the Ryukyu,Manila,Philippine,North Sulawesi,Halmahera,New Britain,Solomon...The Neogene is an important period for studying the onset of subduction,with numerous subduction zones forming in the western Pacific,including the Ryukyu,Manila,Philippine,North Sulawesi,Halmahera,New Britain,Solomon,and New Hebrides subduction zones.However,studies on these subduction zones are relatively independent,so it is important to conduct systematic comparative studies.In this paper,we review the initiation models of Neogene subduction in the western Pacific,with the three typical types of subduction initiation models including polarity-reversal,induced subduction re-initiation,and noninherited subduction initiation to form new ruptures.In addition,the parameters of different subduction zones are collated to form five categories:basic features,subducting plate features,upper plate features,kinematic features,and subsequent activity.The regularity of the subduction processes,the specificity of the different subduction cases,and the possible constraints between the subduction initiation types and the characteristics of the subduction zone parameters are discussed and analyzed.The compiled dataset of the subduction zone parameters can provide data support for related studies.展开更多
Detailed studies indicate that the main rock type of the Neogene high-potassium calc-alkaline volcanic rock association from north Qiangtang is andesite, dacite and rhyolite. They belong to typical crust-generation ma...Detailed studies indicate that the main rock type of the Neogene high-potassium calc-alkaline volcanic rock association from north Qiangtang is andesite, dacite and rhyolite. They belong to typical crust-generation magmatic system and originate from the special thickened crust of the Tibetan Plateau by dehydration melting. This group of rocks exhibits LREE enrichment but no remarkable Eu anomaly that shows their source region should be a thickened deep crust consisting of eclogitic mass group, implying that the crust had been thickened and an eclogitic deep crust had been formed during the Neogene period in Qiangtang area. This understanding is important and significant to making further discussion on the uplift mechanism and continental dynamics of the Tibetan Plateau.展开更多
The Neogene deformation of the Kuqa-Tianshan Basin-range System is character-ized by discrepancy in paleostress patterns on the basin-range boundary and in the basin interior, and by discrepancy in deformation styles ...The Neogene deformation of the Kuqa-Tianshan Basin-range System is character-ized by discrepancy in paleostress patterns on the basin-range boundary and in the basin interior, and by discrepancy in deformation styles of the basement and the cover. Measurement and paleostress reconstruction of the brittle faults display a stress pattern with NW-SE and/or NNW-SSE extension on the basin margin and NW-SE compression in the basin interior. The basement was cut into blocks separated by boundary faults and upthrusts that were recognized in the seismic reflection profile. The block-faulting could have caused vertical uplift of the basement and gravitational sliding in the overlying sedimentary cover. Theoretical calculation indicates two generations of potential decollement folds within the basin, with one being mudstone in the Triassic Huangshanjie formation and the other the Cenozoic salt-gypsum layers.展开更多
The faunal ecological type and sequence in the Tertiary red clay indicate that Hipparion fauna during the period 7.4-6.1 Ma in the middle reaches of the Yellow River is composed mainly of dorcadoides and mixed types. ...The faunal ecological type and sequence in the Tertiary red clay indicate that Hipparion fauna during the period 7.4-6.1 Ma in the middle reaches of the Yellow River is composed mainly of dorcadoides and mixed types. This represents semiarid veld environment with small fluctuation. The fossil assemblages characterized by the abundance of gaudryi types and even the occurrence of some Hominoid and Chalicotherium indicate an obviously warm and humid period since 5.3 Ma. The fossil assemblages during 3.4 Ma show the typical steppe fauna representing dry climate. It is indicated by the changes of ecological sequence that the cli-matic conditions in Pliocene are drier than that in late Mio-cene. The clay-skin content of red clay, which has a syn-chronous change with faunal features, is a rather good re-placing palaeoclimatic index.展开更多
The widely exposed Chinese Neogene terrestrial deposits provide the best circumstance for the establishment of an accurate chronostratigraphic system of Eurasia, and the rapidly evolved mammalian fossils contribute ef...The widely exposed Chinese Neogene terrestrial deposits provide the best circumstance for the establishment of an accurate chronostratigraphic system of Eurasia, and the rapidly evolved mammalian fossils contribute efficiently to the division and correlation of Asian Neogene strata. A uniform Neogene biostratigraphic framework for China has already been established,with seven mammalian ages named. With a developed stratigraphic basis for the geochronologic "ages", seven chronostratigraphic "stage" have been established for the Chinese Neogene terrestrial strata, namely the Miocene Xiejian, Shanwangian,Tunggurian, Bahean, and Baodean stages, and the Pliocene Gaozhuangian and Mazegouan stages. Based on a series of research achievements, refined biostratigraphic, paleomagnetic and isotopic methods were combined and applied to continuous sections,and a Chinese Neogene chronostratigraphic sequence with accurate geological ages was established and improved in recent years. The lower boundaries of most of the stages could be correlated with those of the marine stages in the International Chronostratigraphic Chart, except the Tunggurian Stage, which is correlated with the European land mammal age. The biostratigraphic markers of the Chinese Neogene stages are usually first appearance of a single taxon, some representing regional species replacement, others indicating intercontinental migration of certain taxa. Candidate stratotype sections have been proposed for all the Chinese Neogene stages according to the principle and rule of modern stratigraphy, and other Chinese Neogene strata in different regions are comprehensively correlated.展开更多
Based on a combination of high resolution 3-D seismic, drilling and well logging and core data, this study focuses on describing the depositional features of the Neogene Minghuazhen Formation shallow water delta in Hu...Based on a combination of high resolution 3-D seismic, drilling and well logging and core data, this study focuses on describing the depositional features of the Neogene Minghuazhen Formation shallow water delta in Huanghekou area(HHKA), Bohai offshore basin and discussing the evolution and controlling factors of shallow water delta sandbody. An obvious meandering fluvial delta system developed in sequence 1(SQ1) of the Neogene in HHKA with thinner sandbody of distributary channels and poor development of mouth bar. The sequence texture obviously influences the vertical development and stacking pattern of sandbodies and controls the distribution of sandbodies in plain view as well. In shallow water lacustrine basins, relative topographic height difference leads to change of distribution of accommodation space, and sandbodies of distributary channels usually develop well in local low-lying areas where accommodation space increases. The delta is dominated by distributary channel sandbodies during the early period of base level rising. Sandbodies contact with each other in a lateral stacking pattern and are characterized by a fan shape in plain view. Distributary channels gradually narrow and tend to shift during the mid-late-period of base level rising, while the sandbodies are characterized by a net shape in plain view. During the period of base level slow falling, the multistory/multilateral channel sandbodies dominated the inner front of shallow-water delta and the delta sand dispersal distributes as a lobe shape.展开更多
Analyses of rock-magnetic properties of Neogene sediments of the Taxihe section, northern Tianshan Mountains, show that the section can be classified into three categories including lacustrine facies, fluvial facies a...Analyses of rock-magnetic properties of Neogene sediments of the Taxihe section, northern Tianshan Mountains, show that the section can be classified into three categories including lacustrine facies, fluvial facies and alluvial facies, which correspond to the lower, middle and upper of the Taxihe section respectively. The magnetic minerals of the lacustrine facies may be affected by the process of weath- ering, lithogenesis and biolithogenesis besides the source of the sediments. The natural remanence intensities are between 10-3 A/m and 10-2 A/m. The minerals are dominated by magnetite and the high coercive magnetic mineral may be goethite. The magnetic grains are the mixture of PSD+SD or SD+SP. The natural remanence intensities of the strata of fluvial facies are between 10-2 A/m and 10-1 A/m, about ten times that of the lacustrine facies. The magnetic minerals are mainly magnetite and hematite, and the magnetic grains are mainly PSD. The characteristic remanence (ChRM) carriers are magnetites. In the alluvial facies, the natural remanence intensities are mostly less than 1×10-2 A/m. The magnetic minerals of the series are dominated by magnetite and hematite, almost the same as the fluvial facies. But the difference is that most of the stepwise demagnetization can reveal two components and the ChRM carriers are hematites. The magnetic grains are PSD in terms of the hysteresis parameters.展开更多
The Tortonian–Calabrian strata of Offshore Makran(Pakistan)is investigated for the purpose of reservoir assessment.The stratigraphy and petrophysics indicate that the Neogene sediments have tight reservoir potential ...The Tortonian–Calabrian strata of Offshore Makran(Pakistan)is investigated for the purpose of reservoir assessment.The stratigraphy and petrophysics indicate that the Neogene sediments have tight reservoir potential with porosities in the range of 3%–9%and 40%–50%water saturation.The mineralogical cross plots indicate a mixed lithology with an abundance of dolomite and calcite,together with minor quartz content and shale.The seismic interpretation demonstrates medium–high amplitude reflection patterns,mud diapirs coupled with onlapping strata and the occurrence of bottom simulating reflectors(BSRs).The BSRs are characterized by diminished amplitude,low continuity and exhibiting acoustic blanking zones.The high formation pressure results indicate overpressure zones,suggesting the occurrence of overpressured shales in the Jal Pari-1A.The presence of mud diapirs and gas chimneys are the result of tectonic forces acting at the junction of the Arabian,Indian and Eurasian plates,whereas,BSRs prove the existence of gas charged sediments supporting the formation of mud diapirism in the region.It is concluded that the high rates of sedimentation during the Neogene are likely to have contributed to the development of the high formation pressure.Revised mud weights,casing policies,pore pressure transients and geophysical inversion studies will help alleviate drilling risks in future exploration strategies.展开更多
基金Supported by the PetroChina Science and Technology Project (2021DJ0402,2021DJ0202)。
文摘Based on the data of field outcrops,drilling cores,casting thin sections,well logging interpretation,oil/gas shows during drilling,and oil/gas testing results,and combined with modern salt-lake sediments in the Qinghai Lake,the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics,development patterns,sand control factors,and hydrocarbon accumulation characteristics.Beach-bar sand bodies are widely developed in the Neogene saline lake basin,and they are lithologically fine sandstone and siltstone,with wavy bedding,low-angle cross bedding,and lenticular-vein bedding.In view of spatial-temporal distribution,the beach-bar sand bodies are stacked in multiple stages vertically,migratory laterally,and extensive and continuous in NW-SE trending pattern in the plane.The stacking area of the Neogene beach-bar sandstone is predicted to be 3000 km^(2).The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone,and the debris input from the source area affects the scale and enrichment of beach-bar sandstone.The ancient landform controls the morphology and stacking style of beach-bar sandstone,and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone.The beach-bars have a reservoir-forming feature of“one reservoir in one sand body”,with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction.Three favorable exploration target zones in Zhahaquan,Yingdong-eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements.
基金the Knowledge Innovation Project of the Chinese Academy of Sciences(KZCX2-103) the Major State Basic Research Project of China(G2000077700).
文摘Chinese Neogene Rhinocerotidae has quite a complete record and its temporal range is the Early Miocene to Late Pliocene. The samples include 25 species in 4 tribes of 2 subfamilies. They are used as a foundation for the study of the evolution of the family and its relation to climatic changes. Taxonomic diversity, new records and extinctions are estimated for each Chinese Neogene mammal faunal unit (NMU). The diversity of Chinese Rhinocerotidae varies noticeably throughout the Neogene and is recognized within five stages: the Middle Miocene and Late Miocene are stages of high diversity and the Early Miocene, early Late Miocene and Pliocene are stages of low diversity. Rhinocerotid diversity and morphology are closely related to environmental factors and particularly sensitive to changes in ambient temperature and humidity. The interpretation of climatic variation reflected in the evolution of Rhinocerotidae corresponds precisely with the conclusions drawn from other workers and provides new evidence for research on the Neogene terrestrial ecosystem in China.
基金Supported by the National Natural Science Foundation of China(41772101)China National Science and Technology Major Project(2017ZX05009001-002)
文摘Core, well logging and seismic data were used to investigate sandbody architectural characteristics within Lower Member of Minghuazhen Formation in Neogene, Bohai BZ25 Oilfield, and to analyze the sedimentary microfacies, distribution and internal architecture characteristics of the bar finger within shoal water delta front. The branched sand body within shoal water delta front is the bar finger, consisting of the mouth bar, distributary channel over bar, and levee. The distributary channel cuts through the mouth bar, and the thin levee covers the mouth bar which is located at both sides of distributary channel. The bar finger is commonly sinuous and its sinuosity increases basinward. The distributary channel changes from deeply incising the mouth bar to shallowly incising top of the mouth bar.The aspect ratio ranges from 25 to 50 and there is a double logarithmic linear positive relationship between the width and thickness for the bar finger, which is controlled by base-level changing in study area. For the bar finger, injection and production in the same distributary channel should be avoided during water flooding development. In addition, middle–upper distributary channel and undrilled mouth bar are focus of tapping remaining oil.
文摘The west block of the middle belt of TanLu fault belt is one of the areas where volcanic landforms are mainly distributed. This paper divides the volcanic landforms into four grades according to formation, morphology, and ingredient of matter. Lava cones are divided into two types based on the force of top-support and the fluid form of magma: the arc-projecting type and spring-spilling type. Furthermore, the courses of development of volcanic landforms are divided into three stages according to the form and strength of volcanic activities.
文摘Sandstones from the Neogene Siwalik successions of the East and West Siang Districts of Arunachal Pradesh were analyzed to evaluate source-area weathering,provenance,and tectonic setting by using major,trace,and rare earth elements(REEs)as proxies.The sandstones are classified as lithic arenite and wacke arenite based on their mineralogical compositions.The values of different weathering indices such as Chemical Index of Alteration(CIA;60.93–89.86)and Chemical Index of Weathering(CIW;40–96.8)suggest moderate to intense weathering in the source area.The plot of Th/Sc versus Zr/Sc indicates enrichment of zircon by sediment sorting and/or recycling from a weathered source.The high positive correlation between Al2 O_(3) and K2 O points towards a strong influence of the constituent clay minerals on the major oxide composition of the sandstones.Petrographic analysis together with enriched LREE,flat HREE,negative Eu anomalies(Eu/Eu^(*)=0.47 to 0.90)in the chondrite-normalized diagrams,and the ratios of La/Sc,La/Co,Th/Sc,Th/Co,Cr/Th collectively suggests that the Neogene sediments were derived from felsic igneous and/or reworked sedimentary/metasedimentary sources in an upper continental crustal setting.The geochemical characteristics of the studied Neogene Siwalik sandstones indicate that the sediments were sourced from pre-Himalayan gneisses and granitoids together with metabasic rocks,which had formed in a passive margin tectonic setup.
基金supported by the Impact and Response of Antarctic Seas to Climate Change Project (IRASCC01-03-01)Hainan Naturtal Science Foundation Inovative Research Team Project (421CXTD441)the National Natural Science Foundation of China (Nos. 42176067, 41576069, 42176055, 41776189 and 41906197)
文摘The Neogene Terror Rift in the Antarctic Victoria Land Basin(VLB)of the Ross Sea,Antarctica,is composed of the Discovery Graben and the Lee Arch.Many Neogene volcanoes are aligned in the north-south direction in the southern VLB,belonging to the McMurdo Volcanic Group.However,due to multiple glaciations and limited seismic data,the volcanic processes are still unclear in the northern VLB,especially in the Terror Rift.Multichannel seismic profiles were collected at the VLB from the 32nd Chinese National Antarctic Research Expedition(CHINARE).We utilized four seismic profiles from the CHINARE and additional historical profiles,along with gravity and magnetic anomalies,to analyze faults and stratigraphic characteristics in the northern Terror Rift and volcanism in the VLB.Negative flower structures found in the northern Terror Rift suggest that the Terror Rift was affected by dextral strike-slip faults extending from the northern Victoria Land(NVL).After the initial orthogonal tension,the rift transited into an oblique extension,forming a set of downward concaving normal faults and accommodation zones in the Terror Rift.On the Lee Arch,several imbricated normal faults formed and converged into a detachment fault.Under gravitational forces,the strata bent upward and formed a rollover anticline.Many deep faults and thin strata subjected to erosion facilitated volcanic activity.A brittle volcanic region in the VLB was affected by dextral strike-slip movements and east-west extension,resulting in two Neogene volcanic chains that connect three igneous provinces in the VLB:the Hallett,Melbourne,and Erebus Provinces.These two chains contain mud volcanoes with magnetic nuclei,volcanic intrusions,and late-stage volcanic eruptions.Volcanisms have brought about opposite polarities of magnetic anomalies in Antarctica,indicating the occurrence of multiple volcanic activities.
基金Supported by the China National Science and Technology Major Project(2016ZX05024-003)。
文摘By using drilling,high-precision 3 D seismic data,data of geochemistry,logging and testing,the reservoir characteristics and accumulation conditions of the KL6-1 lithologic oilfield in the Laibei Low Uplift in the Bohai Sea are examined comprehensively.The study shows that:KL6-1 oilfield is a monolithic,high-quality,large-scale Neogene lithologic oilfield featuring shallow reservoir depth,high productivity,concentrated oil-bearing intervals,large oil-bearing area,and high reserve abundance;hydrocarbon source supply from two directions provides a sufficient material basis for the formation of large oil field;two types of"inherited structural ridge"developed under the effect of block rotation,late active faults formed by Neotectonic movement,and widely distributed contiguous sand bodies provide an efficient oil and gas transportation system for the large-scale accumulation of oil and gas;contiguous channel and lacustrine lowstand system sand bodies developed in low accommodation condition provide the basic condition for the formation of large-scale lithologic traps;deep formations structural ridge,faults(dominant migration pathways)and large-scale superimposed contiguous sand bodies constitute a"vine type"oil and gas migration and accumulation system in the Laibei Low Uplift,which is conducive to the formation of large-scale and high-abundance lithologic reservoir in this area.The successful discovery of KL6-1,100 million ton reserve order lithologic oil field,has revealed the exploration potential of Neogene large lithologic reservoirs in Bohai Sea,expanded the exploration field,and also has certain reference significance for the exploration of large lithologic reservoirs in similar areas.
文摘Geochemical analysis of Neogene mudrocks from Sitakund anticline, Chittagong Tripura Fold Belt (CTFB), Bengal Basin, Bangladesh, was deployed to delineate the provenance, tectonics and depositional environments. Representative samples went through mineralogical and geochemical analysis concerning major, trace and rare earth element analysis. Rigaku ZSX Primus and NITON XL3t 800 XRF instruments were utilized for the determination of major and trace elements. The experiment results reveal that the Neogene mudrocks are rich in silica having concentration of 58.10% to 62.60% with an average of 59.90%. Therefore, the geochemical response from the experiments apparently proved the existence of the active continental margin setting for the Neogene mudrocks. Different concentrations and ratios of major oxides satisfy that the mudrocks were derived from felsic source rocks. In addition, chemical index of alteration (CIA) values for the Neogene mudrocks vary from 67.81 to 77.57 with an average 74.41 indicating significant weathering at the source areas. Moreover, U/Th, Cu/Zn, Ni/Co and V/Cr ratios designate that the mudrocks were deposited in oxidizing depositional environment.
基金supported by the Second Comprehensive Scientific Expedition on the Tibetan Plateau(Grant No.2019QZKK0705)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB26030000,XDA20070203)the National Natural Science Foundation of China(Grant Nos.41872005,41872006)。
文摘The remarkable uplift of the Tibetan Plateau in the Neogene had great impacts on the climate and environment of East Asia and even the world.Therefore,establishment of the Neogene stratigraphic framework of the Tibetan Plateau is of great significance to research in various fields of geosciences.Based on marine sediments,the international chronostratigraphic system of the Neogene is divided into six stages in the Miocene and two stages in the Pliocene.Since the beginning of the Cenozoic,the share of terrestrial strata on continents has increased rapidly.By the Neogene,it had far exceeded that of marine strata,and almost all deposits on the Tibetan Plateau and its surrounding areas were terrestrial strata.In China,the Miocene includes five stages and the Pliocene includes two stages.Except for the Tunggurian of the Miocene,which has a lower boundary at 15 Ma,the other stages have the same paleomagnetic definitions and time intervals as the corresponding international marine stages.Mammalian fossils play a very important role in the division and correlation of Cenozoic terrestrial strata,and rodent,carnivore,proboscidean,perissodactyl and artiodactyl fossils are especially important in Neogene terrestrial biostratigraphy.There are many basins with well-exposed strata and abundant mammalian fossils in the Tibetan Plateau.The lower boundary stratotype sections of the Neogene Xiejian and Bahean stages are located respectively in the Xining and Linxia basins,and there are precise paleomagnetic dates in coordination with mammalian fossils.The lower boundary stratotypes of other stages can also be effectively determined in the Tibetan Plateau.Many first appearing mammalian genera in East Asia also appeared in the Tibetan Plateau and its surrounding areas,especially in the Linxia Basin on the northeast margin and in the Siwaliks on the southwest margin.Among them,Prodeinotherium first appeared at the bottom of the Miocene in the Siwaliks,and the earliest Hipparion of the Old World first appeared at the bottom of the Bahean Stage in the Linxia Basin.Carbon and oxygen isotope analysis of enamel and paleosols of Cenozoic sediments and mammal fossils in the Tibetan Plateau and its surrounding areas have been used to reconstruct the climate,environment and vegetation development characteristics,and revealed that these changes were not only related to global change,but also had regional features.Evidence of the Late Miocene C4plant expansion event based on carbon isotope changes comes from the southern margin of the Tibetan Plateau,but in sharp contrast,δ13C indicates that there was still no clear or significant C4plant signal on the northern margin of the Tibetan Plateau until the end of the Neogene.Theδ18O analysis shows that there were several major climate change events in the Cenozoic,especially in the Late Miocene at about 7 Ma,when positive drift ofδ18O indicates that the northern and southern sides of the Tibetan Plateau were changing to drier environments.The strong uplift of the Tibetan Plateau in the Late Miocene strengthened the thermal contrast between sea and land,which strengthened monsoon circulation and led to the expansion of C4vegetation in South Asia.However,the East Asian summer monsoon,which can bring atmospheric precipitation and a climate suitable for C4plants to northern China,was not enough to affect the northern Tibetan Plateau.The Tibetan Plateau on the whole rose to an altitude of about 3000 m in the Miocene,becoming a barrier to mammalian migration;it reached its modern altitude of more than 4000 m in the Pliocene,thus forming a cryosphere environment,which led to the emergence of ancestral types of the Ice Age fauna.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91858212, 91858214, and 41906056)。
文摘The Neogene is an important period for studying the onset of subduction,with numerous subduction zones forming in the western Pacific,including the Ryukyu,Manila,Philippine,North Sulawesi,Halmahera,New Britain,Solomon,and New Hebrides subduction zones.However,studies on these subduction zones are relatively independent,so it is important to conduct systematic comparative studies.In this paper,we review the initiation models of Neogene subduction in the western Pacific,with the three typical types of subduction initiation models including polarity-reversal,induced subduction re-initiation,and noninherited subduction initiation to form new ruptures.In addition,the parameters of different subduction zones are collated to form five categories:basic features,subducting plate features,upper plate features,kinematic features,and subsequent activity.The regularity of the subduction processes,the specificity of the different subduction cases,and the possible constraints between the subduction initiation types and the characteristics of the subduction zone parameters are discussed and analyzed.The compiled dataset of the subduction zone parameters can provide data support for related studies.
基金the National Natural Science Foundation of China (Grant No. 40072029) and the National Key Project for Basic Research on the Tibetan Plateau (G1998040801).
文摘Detailed studies indicate that the main rock type of the Neogene high-potassium calc-alkaline volcanic rock association from north Qiangtang is andesite, dacite and rhyolite. They belong to typical crust-generation magmatic system and originate from the special thickened crust of the Tibetan Plateau by dehydration melting. This group of rocks exhibits LREE enrichment but no remarkable Eu anomaly that shows their source region should be a thickened deep crust consisting of eclogitic mass group, implying that the crust had been thickened and an eclogitic deep crust had been formed during the Neogene period in Qiangtang area. This understanding is important and significant to making further discussion on the uplift mechanism and continental dynamics of the Tibetan Plateau.
文摘The Neogene deformation of the Kuqa-Tianshan Basin-range System is character-ized by discrepancy in paleostress patterns on the basin-range boundary and in the basin interior, and by discrepancy in deformation styles of the basement and the cover. Measurement and paleostress reconstruction of the brittle faults display a stress pattern with NW-SE and/or NNW-SSE extension on the basin margin and NW-SE compression in the basin interior. The basement was cut into blocks separated by boundary faults and upthrusts that were recognized in the seismic reflection profile. The block-faulting could have caused vertical uplift of the basement and gravitational sliding in the overlying sedimentary cover. Theoretical calculation indicates two generations of potential decollement folds within the basin, with one being mudstone in the Triassic Huangshanjie formation and the other the Cenozoic salt-gypsum layers.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 49972004).
文摘The faunal ecological type and sequence in the Tertiary red clay indicate that Hipparion fauna during the period 7.4-6.1 Ma in the middle reaches of the Yellow River is composed mainly of dorcadoides and mixed types. This represents semiarid veld environment with small fluctuation. The fossil assemblages characterized by the abundance of gaudryi types and even the occurrence of some Hominoid and Chalicotherium indicate an obviously warm and humid period since 5.3 Ma. The fossil assemblages during 3.4 Ma show the typical steppe fauna representing dry climate. It is indicated by the changes of ecological sequence that the cli-matic conditions in Pliocene are drier than that in late Mio-cene. The clay-skin content of red clay, which has a syn-chronous change with faunal features, is a rather good re-placing palaeoclimatic index.
基金supported by the National Natural Science Foundation of China (Grant No. 41430102)the Strategic Priority Cultivating Research Program, Chinese Academy of Sciences (Grant No. XDPB05)+2 种基金the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. QYZDY-SSWDQC022)the Science and Technology Basic Work Research Program (Grant No. 2015FY310100-14)and the Chinese Commission on Stratigraphy (Grant No. DD20160120-04)
文摘The widely exposed Chinese Neogene terrestrial deposits provide the best circumstance for the establishment of an accurate chronostratigraphic system of Eurasia, and the rapidly evolved mammalian fossils contribute efficiently to the division and correlation of Asian Neogene strata. A uniform Neogene biostratigraphic framework for China has already been established,with seven mammalian ages named. With a developed stratigraphic basis for the geochronologic "ages", seven chronostratigraphic "stage" have been established for the Chinese Neogene terrestrial strata, namely the Miocene Xiejian, Shanwangian,Tunggurian, Bahean, and Baodean stages, and the Pliocene Gaozhuangian and Mazegouan stages. Based on a series of research achievements, refined biostratigraphic, paleomagnetic and isotopic methods were combined and applied to continuous sections,and a Chinese Neogene chronostratigraphic sequence with accurate geological ages was established and improved in recent years. The lower boundaries of most of the stages could be correlated with those of the marine stages in the International Chronostratigraphic Chart, except the Tunggurian Stage, which is correlated with the European land mammal age. The biostratigraphic markers of the Chinese Neogene stages are usually first appearance of a single taxon, some representing regional species replacement, others indicating intercontinental migration of certain taxa. Candidate stratotype sections have been proposed for all the Chinese Neogene stages according to the principle and rule of modern stratigraphy, and other Chinese Neogene strata in different regions are comprehensively correlated.
基金supported by the National Science and Technology Major Project(Exploration Technologies for Offshore Subtle Oil/Gas)(project no.:2016ZX05024–003-003)the Fundamental Research Funds for the Central Universities for support
文摘Based on a combination of high resolution 3-D seismic, drilling and well logging and core data, this study focuses on describing the depositional features of the Neogene Minghuazhen Formation shallow water delta in Huanghekou area(HHKA), Bohai offshore basin and discussing the evolution and controlling factors of shallow water delta sandbody. An obvious meandering fluvial delta system developed in sequence 1(SQ1) of the Neogene in HHKA with thinner sandbody of distributary channels and poor development of mouth bar. The sequence texture obviously influences the vertical development and stacking pattern of sandbodies and controls the distribution of sandbodies in plain view as well. In shallow water lacustrine basins, relative topographic height difference leads to change of distribution of accommodation space, and sandbodies of distributary channels usually develop well in local low-lying areas where accommodation space increases. The delta is dominated by distributary channel sandbodies during the early period of base level rising. Sandbodies contact with each other in a lateral stacking pattern and are characterized by a fan shape in plain view. Distributary channels gradually narrow and tend to shift during the mid-late-period of base level rising, while the sandbodies are characterized by a net shape in plain view. During the period of base level slow falling, the multistory/multilateral channel sandbodies dominated the inner front of shallow-water delta and the delta sand dispersal distributes as a lobe shape.
基金Supported by Major State Basic Research Program of China (Grant No. 2001 CB409804).
文摘Analyses of rock-magnetic properties of Neogene sediments of the Taxihe section, northern Tianshan Mountains, show that the section can be classified into three categories including lacustrine facies, fluvial facies and alluvial facies, which correspond to the lower, middle and upper of the Taxihe section respectively. The magnetic minerals of the lacustrine facies may be affected by the process of weath- ering, lithogenesis and biolithogenesis besides the source of the sediments. The natural remanence intensities are between 10-3 A/m and 10-2 A/m. The minerals are dominated by magnetite and the high coercive magnetic mineral may be goethite. The magnetic grains are the mixture of PSD+SD or SD+SP. The natural remanence intensities of the strata of fluvial facies are between 10-2 A/m and 10-1 A/m, about ten times that of the lacustrine facies. The magnetic minerals are mainly magnetite and hematite, and the magnetic grains are mainly PSD. The characteristic remanence (ChRM) carriers are magnetites. In the alluvial facies, the natural remanence intensities are mostly less than 1×10-2 A/m. The magnetic minerals of the series are dominated by magnetite and hematite, almost the same as the fluvial facies. But the difference is that most of the stepwise demagnetization can reveal two components and the ChRM carriers are hematites. The magnetic grains are PSD in terms of the hysteresis parameters.
文摘The Tortonian–Calabrian strata of Offshore Makran(Pakistan)is investigated for the purpose of reservoir assessment.The stratigraphy and petrophysics indicate that the Neogene sediments have tight reservoir potential with porosities in the range of 3%–9%and 40%–50%water saturation.The mineralogical cross plots indicate a mixed lithology with an abundance of dolomite and calcite,together with minor quartz content and shale.The seismic interpretation demonstrates medium–high amplitude reflection patterns,mud diapirs coupled with onlapping strata and the occurrence of bottom simulating reflectors(BSRs).The BSRs are characterized by diminished amplitude,low continuity and exhibiting acoustic blanking zones.The high formation pressure results indicate overpressure zones,suggesting the occurrence of overpressured shales in the Jal Pari-1A.The presence of mud diapirs and gas chimneys are the result of tectonic forces acting at the junction of the Arabian,Indian and Eurasian plates,whereas,BSRs prove the existence of gas charged sediments supporting the formation of mud diapirism in the region.It is concluded that the high rates of sedimentation during the Neogene are likely to have contributed to the development of the high formation pressure.Revised mud weights,casing policies,pore pressure transients and geophysical inversion studies will help alleviate drilling risks in future exploration strategies.
