A wide northeast-trending belt of intraplate alkaline volcanism,exhibiting similar geochemical characteristics,stretches from the Eastern Atlantic Ocean to the Cenozoic rift system in Europe.Its formation is associate...A wide northeast-trending belt of intraplate alkaline volcanism,exhibiting similar geochemical characteristics,stretches from the Eastern Atlantic Ocean to the Cenozoic rift system in Europe.Its formation is associated with both passive and active mechanisms,but it remains a source of ongoing debate among geoscientists.Here,we show that seismic whole-mantle tomography models consistently identify two extensive low-velocity anomalies beneath the Canary Islands(CEAA)and Western-Central Europe(ECRA)at mid-mantle depths,merging near the core-mantle boundary.These low-velocity features are interpreted as two connected broad plumes originating from the top of the African LLSVP,likely feeding diapir-like upwellings in the upper mantle.The CEAA rises vertically,whereas the ECRA is tilted and dissipates at mantle transition zone depths,possibly due to the interaction with the cold Alpine subducted slab,which hinders its continuity at shallower depths.While plate-boundary forces are considered the primary drivers of rifting,the hypothesis that deep mantle plumes play a role in generating volcanic activity provides a compelling explanation for the European rift-related alkaline volcanism,supported by geological,geophysical,and geochemical evidence.展开更多
Previous studies have indicated that sediment gravity flow deposits developed in lacustrine active extensional rift basins are primarily influenced by tectonics and to a lesser extent by climate.Our present work revea...Previous studies have indicated that sediment gravity flow deposits developed in lacustrine active extensional rift basins are primarily influenced by tectonics and to a lesser extent by climate.Our present work reveals that climate can obscure the effect of tectonic subsidence by regulating sediment supply;conversely,tectonics can impede the sedimentary manifestation of climatic impacts.Here a case study has been presented to assess the impact of climate-modulated rapid lake-level rise and tectonic subsidence on the development of coarse-grained gravity flow deposits in the Dongying rift margin of the Bohai Bay Basin,eastern China.The lithofacies analysis reveals frequent bed amalgamation,abundant thick massive coarse-grained deposits,widespread cross bedding and plant fragments,and incomplete composite bed formed by high-energy erosion,indicating that the hyperpycnal flow is an important mechanism driving the deposition of these coarse-grained sediments.Detailed sequence stratigraphic analysis and sediment dispersal pattern suggest that the long-striped nearshore subaqueous fan systems induced by outburst-flood hyperpycnal flow distributed along the border fault,are primarily controlled by long-term tectonics,while the rapid rise of lake level driven by short-term climate change possibly intensifies seasonal flood-generated hyperpycnal flow occurrences and consequently promotes the basinal fan progradation.The maximum scale of these coarse-grained gravity flow deposits of the basinal fan systems are typically attained during the transgressive systems tract,which deviates from the classical sequence stratigraphic model.Furthermore,it presented a continuous transition from the proximal to the distal part,encompassing traction flows and turbidity currents during the periods of relatively stable tectonics.Nevertheless,gravel-rich debris flows appear to predominate the dispersion of coarse-grained sediments during periods characterized by intense tectonic activity.The coarse-grained gravity flow deposits in the lacustrine rift margin reported here,challenge the traditional beliefs:this study suggests that subaqueous deposits abundantly preserved in the transgressive setting.展开更多
The Cambrian Qiongzhusi Formation in the Sichuan Basin harbors significant potential for shale gas harvesting.However,systematic disparities in mineral composition and reservoir architecture have been observed between...The Cambrian Qiongzhusi Formation in the Sichuan Basin harbors significant potential for shale gas harvesting.However,systematic disparities in mineral composition and reservoir architecture have been observed between intra-and extra-trough reservoirs within the Deyang-Anyue Rift Trough.These variations were primarily determined by divergences in the sedimentary environments developed during the evolution of the rift trough,which were a main factor in fostering the heterogeneous distribution of shale gas enrichment found today.However,the genetic mechanisms that govern reservoir heterogeneity across distinct structural domains(intra-trough,trough margin,and extra-trough)remain poorly understood,particularly regarding the coupling relationships between depositional environments,reservoir characteristics,and gas-bearing properties.This study adopts a multidisciplinary approach to investigating this issue that integrates core analysis,well-log interpretations,and geochemical data.Through systematic comparisons conducted using X-ray diffraction mineralogy,organic carbon quantification,and spontaneous imbibition experiments,we characterize the mineral assemblages,organic geochemical signatures,and pore structures found across the three structural domains of the Deyang-Anyue Rift Trough.The key findings are as follows:(1)The depositional environment is the main influence on reservoir distribution and organic matter enrichment,with intra-trough shales exhibiting a higher abundance of organic matter than their trough-margin and extra-trough counterparts.(2)Enhanced brittleness in intra-trough zones correlates with the predominance of biogenic silica therein.(3)Synergistic organic-inorganic interactions govern pore system development.(4)Gas-bearing capacity is jointly determined by effective porosity and organic matter content.These findings establish the rift trough as a preferential exploration target,providing critical geological guidance for optimizing shale gas exploration strategies in the Cambrian Qiongzhusi Formation.展开更多
In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whe...In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whether the combined patterns of grabens in the Hailar Basin exhibit similar characteristics to those in other NE China rift basins and to identify the underlying causes.To achieve this,a comprehensive analysis of the major fault systems and the combined patterns of faulted sub-depressions,as well as their controlling mechanisms,was conducted.This analysis utilized the latest 3D seismic data that cover nearly the entire Beier Depression.Three groups of pre-existing fault systems were observed in the basement of the Beier Depression,and they are the NEE-EW-trending fault systems,the NE-trending fault systems,and the NW-trending fault systems.The NEE-EW-trending fault systems were distributed in the central part of the Beier Depression and primarily controlled the sedimentary filling of the Tongbomiao and the Lower Nantun Formations.The NE-trending fault systems were distributed in the southwestern part of the Beier Depression and primarily controlled the sedimentary filling of the Upper Nantun Formations.The NW-trending fault systems were distributed rarely in the Beier Depression.Five kinds of combined patterns of the sub-depressions were developed in the Beier Depression,and they are the parallel,en echelon,face-to-face,back-to-back,and S-shaped combined patterns.They were controlled by the NEE-EW-trending and the NE-trending fault systems with different orientations,arrangements,and activation sequences.展开更多
Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and...Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.展开更多
Taking the natural gas reservoirs of the Sinian Dengying Formation on the east and west sides(Gaoshiti-Moxi area and north slope of central Sichuan paleo-uplift on the east;Weiyuan and Well Datan-1 block on the west)o...Taking the natural gas reservoirs of the Sinian Dengying Formation on the east and west sides(Gaoshiti-Moxi area and north slope of central Sichuan paleo-uplift on the east;Weiyuan and Well Datan-1 block on the west)of the Deyang-Anyue rift trough in the Sichuan Basin,China,as the research object,the geochemical parameters(component,isotopic composition)of natural gas from the Dengying Formation in different areas are compared,and then the differences in geochemical characteristics of Dengying natural gas on the east and west sides of the Deyang-Anyue rift trough and their genesis are clarified.First,the Dengying gas reservoirs on both sides of the rift trough are predominantly composed of oil-cracking gas with high maturity,which is typical dry gas.Second,severely modified by thermochemical sulfate reduction(TSR)reaction,the Dengying gas reservoirs on the east side exhibit high H2S and CO_(2) contents,with an elevated δ^(13)C_(2) value(average value higher than-29‰).The Dengying gas reservoirs in the Weiyuan area are less affected by TSR modification,though the δ^(13)C_(1) values are slightly greater than that of the reservoirs on the east side with partial reversal of carbon isotope composition,likely due to the water-soluble gas precipitation and accumulation mechanism.The Dengying gas reservoir of Well Datan-1 shows no influence from TSR.Third,the Dengying gas reservoirs reflect high helium contents(significantly higher than that on the east side)in the Weiyuan and Datan-1 areas on the west side,which is supposed to attribute to the widespread granites in basement and efficient vertical transport along faults.Fourth,controlled by the paleo-salinity of water medium in the depositional period of the source rock,the δ^(2)HCH_(4) values of the Dengying gas reservoirs on the west side are slightly lighter than those on the east side.Fifth,the Dengying natural gas in the Datan-1 area is contributed by the source rocks of the Sinian Doushantuo Formation and the third member of the Dengying Formation,in addition to the Cambrian Qiongzhusi Formation.展开更多
Rift Valley fever virus(RVFV)is a high-containment pathogen that causes severe diseases in humans,with no approved therapeutics available.Its classification as a biosafety level 3(BSL-3)agent has limited research and ...Rift Valley fever virus(RVFV)is a high-containment pathogen that causes severe diseases in humans,with no approved therapeutics available.Its classification as a biosafety level 3(BSL-3)agent has limited research and therapeutic development due to safety concerns.In this study,we developed a stable replicon cell line maintaining the replication of L and S genomic segments of RVFV.Single-cycle viral replicon particles(VRPs)could be efficiently packaged through trans-complementation of glycoproteins from different strains,recapitulating authentic viral entry and replication while minimizing biosafety risks.Using this system,we conducted high-throughput screening of a small-molecule compound library and identified CNX-1351 as an antiviral agent for multiple RNA viruses.Mechanistic studies revealed that CNX-1351 inhibits viral replication,potentially by targeting the PI3K-Akt signaling pathway.This single-cycle VRP system provides a valuable tool for studying RVFV biology,host interactions,antiviral and vaccine development under reduced biosafety constraints.展开更多
Based on sedimentary characteristics of the fine-grained rocks of the lower submember of second member of the Lower Cretaceous Shahezi Formation(K_(1)sh_(2)^(L))in the Lishu rift depression,combined with methods of or...Based on sedimentary characteristics of the fine-grained rocks of the lower submember of second member of the Lower Cretaceous Shahezi Formation(K_(1)sh_(2)^(L))in the Lishu rift depression,combined with methods of organic petrology,analysis of major and trace elements as well as biological marker compound,the enrichment conditions and enrichment model of organic matter in the fine-grained sedimentary rocks in volcanic rift lacustrine basin are investigated.The change of sedimentary paleoenvironment controls the vertical distribution of different lithofacies types in the K_(1)sh_(2)^(L)and divides it into the upper and lower parts.The lower part contains massive siliceous mudstone with bioclast-bearing siliceous mudstone,whereas the upper part is mostly composed of laminated siliceous shale and laminated fine-grained mixed shale.The kerogen types of organic matter in the lower and upper parts are typesⅡ_(2)–Ⅲand typesⅠ–Ⅱ_(1),respectively.The organic carbon content in the upper part is higher than that in the lower part generally.The enrichment of organic matter in volcanic rift lacustrine basin is subjected to three favorable conditions.First,continuous enhancement of rifting is the direct factor increasing the paleo-water depth,and the rise of base level leads to the expansion of deep-water mudstone/shale deposition range.Second,relatively strong underwater volcanic eruption and rifting are simultaneous,and such event can provide a lot of nutrients for the lake basin,which is conducive to the bloom of algae,resulting in higher productivity of typesⅠ–Ⅱ_(1)kerogen.Third,the relatively dry paleoclimate leads to a decrease in input of fresh water and terrestrial materials,including TypeⅢkerogen from terrestrial higher plants,resulting in a water body with higher salinity and anoxic stratification,which is more favorable for preservation of organic matter.The organic matter enrichment model of fine-grained sedimentary rocks of volcanic rift lacustrine basin is established,which is of reference significance to the understanding of the organic matter enrichment mechanism of fine-grained sedimentary rocks of Shahezi Formation in Songliao Basin and even in the northeast China.展开更多
By benchmarking with the iteration of drilling technology,fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and develop...By benchmarking with the iteration of drilling technology,fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin,East China,the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development,drilling and fracturing technologies.The technology system supports the rapid growth of shale oil production and reduces the development investment cost.By comparing it with the shale oil development technology in the United States,the prospect of the shale oil development technology iteration in continental rift lake basins is proposed.It is suggested to continuously strengthen the overall three-dimensional development,improve the precision level of engineering technology,upgrade the engineering technical indicator system,accelerate the intelligent optimization of engineering equipment,explore the application of complex structure wells,form a whole-process integrated quality management system from design to implementation,and constantly innovate the concept and technology of shale oil development,so as to promote the realization of extensive,beneficial and high-quality development of shale oil in continental rift lake basins.展开更多
Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.Th...Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.The study shows that the Central African Rift System mainly develops high-quality lacustrine source rocks in the Lower Cretaceous,and the West African Rift System mainly develops high-quality terrigenous organic matter-rich marine source rocks in the Upper Cretaceous,and the two types of source rocks provide a material basis for the enrichment of oil and gas in the CWARS.Multiple sets of reservoir rocks including fractured basement and three sets of regional cap rocks in the Lower Cretaceous,the Upper Cretaceous,and the Paleogene are developed in the CWARS.Since the Late Mesozoic,due to the geodynamic factors including the dextral strike-slip movement of the Central African Shear Zone,the basins in different directions of the CWARS differ in terms of rifting stages,intervals of regional cap rocks,trap types and accumulation models.The NE-SW trending basins have mainly preserved one stage of rifting in the Early Cretaceous,with regional cap rocks developed in the Lower Cretaceous strata,forming traps of reverse anticlines,flower-shaped structures and basement buried hill,and two types of hydrocarbon accumulation models of"source and reservoir in the same formation,and accumulation inside source rocks"and"up-source and down-reservoir,and accumulation below source rocks".The NW–SE basins are characterized by multiple rifting stages superimposition,with the development of regional cap rocks in the Upper Cretaceous and Paleogene,forming traps of draping anticlines,faulted anticlines,antithetic fault blocks and the accumulation model of"down-source and up-reservoir,and accumulation above source rocks".The combination of reservoir and cap rocks inside source rocks of basins with multiple superimposed rifting stages,as well as the lithologic reservoirs and the shale oil inside source rocks of strong inversion basins are important fields for future exploration in basins of the CWARS.展开更多
It is essential to intensify research on the strike-slip tectonic system in West and Central Africa to better understand regional tectonic evolution and achieve future breakthroughs in oil and gas exploration.Based on...It is essential to intensify research on the strike-slip tectonic system in West and Central Africa to better understand regional tectonic evolution and achieve future breakthroughs in oil and gas exploration.Based on the structural interpretation of extensive seismic data and stratigraphic paleontological analysis of more than 50 wells, this study investigated the tectonic history, sedimentary filling, and evolution of the rift basins in the West and Central Africa, and identified a novel type of intraplate strike-slip tectonic system. It exhibits the following characteristics:(i) the strike-slip tectonic system in the West and Central Africa consists of the Central African Shear Zone(CASZ) and two rift branches, manifesting as an N-shape;(ii) most of basins and rifts are characterized by rapid subsidence at one end and substantial sedimentary thickness;(iii) two types of strike-slip basins are developed, namely the transform-normal extensional basin(TEB) along CASZ and the strike-slip-induced extensional basin(SEB) at each end of CASZ;(iv) two types of basins display their own temporal and spatial evolution history. TEBs underwent two rifting stages during the Early and Late Cretaceous, with a strong inversion at the end of the Late Cretaceous. SEBs experienced three rifting stages, i.e., the Early Cretaceous, Late Cretaceous, and Paleogene, with a weak inversion;and(v) this strike-slip tectonic system was formed under intraplate divergent field, indicating a new type of system. This discovery enhances understanding of the breakup of Gondwana and provides valuable guidance for future oil and gas exploration.展开更多
The Wadi Natash volcanic field(WNVF)in the south of the Eastern Desert of Egypt is a typical example of well-preserved intraplate alkaline magmatism during the Late Cretaceous,i.e.,prior to the Oligo-Miocene Red Sea r...The Wadi Natash volcanic field(WNVF)in the south of the Eastern Desert of Egypt is a typical example of well-preserved intraplate alkaline magmatism during the Late Cretaceous,i.e.,prior to the Oligo-Miocene Red Sea rift.We compiled stratigraphic sections at two sectors;namely East Gabal Nuqra and West Khashm Natash(WKN)where the volcanic flows are intercalated with the Turonian Abu Agag sandstone with occasional paleosols when volcanic activity is intermittent.Peridotite mantle xenoliths are encountered in the first sector whereas flows in the second sector are interrupted by trachyte plugs and ring dykes.On a geochemical basis,the maifc melt originating from the lithospheric mantle beneath the WNVF practiced~5%partial melting of phlogopite-bearing garnet peridotite.Basalts dominate in the two sectors and highly evolved(silicic)rocks are confined to the WKN sector.Rejuvenation of ancient Precambrian fractures following the NW-SE and ENE-WSW trends facilitated the ascend of Late Cretaceous mantle-derived alkaline magma.Structurally,the WNVF developed at the eastern shoulder of the so-called"Kom Ombo-Nuqra-Kharit rift system"that represents a well-defined NW-trending intracontinental rift basin in the southern Eastern Desert.In such a structural setup,the Natash volcanic are confined to half-grabens at the East Gabal Nuqra sector whereas the West Khashm Natash sector is subjected to extensional stresses that propagated eastwards.The WNVF is a typical example of fluvial clastics(Turonian)intercalation with rift-related alkaline volcanic rocks in northeast Africa.展开更多
The Mesoproterozoic rifts are developed in the Ordos Basin located in the western margin of the North China Plate.Based on the latest 3D seismic data and previous research results,this study intends to discuss the zon...The Mesoproterozoic rifts are developed in the Ordos Basin located in the western margin of the North China Plate.Based on the latest 3D seismic data and previous research results,this study intends to discuss the zonal differential deformation characteristics and genetic mechanism of the Mesoproterozoic rifts in the Ordos Basin.NE-trending rifts are developed in the Mesoproterozoic in the south-central Ordos Basin,the main part of which are located near the western margin of the North China Plate.NNW-trending rifts are developed in the north of the basin,while NW-NNW rifts in the Mesoproterozoic in Hangjinqi area.The genetic mechanism of the Mesoproterozoic rifts is related to regional extensional stress field,plate boundary conditions and internal preexisting structures.The main extensional stress direction strikes NWW-SSE(120°)in the western margin of the North China Plate,based on the forward rift trend of the northern Mesoproterozoic.In Hangjinqi area,the reactivation of the existing NWtrending Wulansu fault and NW-NW-trending Daolao fault,results in dextral shear stress field.The boundary between the western margin of the North China Plate and its adjacent plates forms a nearly NS-trending preexisting basement tectonic belt,which intersects with the NWW-SSE(120°)extensional stress at an acute angle of 60°.Therefore,the western margin of the North China Plate is formed by oblique normal faults under oblique extension.Due to the long time span of Columbia Supercontinent breakup(1.8e1.6 Ga),the oblique rift in the south-central Ordos Basin is formed under the continuous oblique extension at the western margin of the North China Plate.展开更多
Background: Vaccinations for animals are crucial for food production, animal welfare, public health, and animal health. They are an affordable way to stop animal sickness, increase food production efficiency, and less...Background: Vaccinations for animals are crucial for food production, animal welfare, public health, and animal health. They are an affordable way to stop animal sickness, increase food production efficiency, and lessen or stop the spread of zoonotic diseases to humans. Animal vaccines that are both safe and efficacious are vital to modern culture. The vaccine should induce a strong, protective and prolonged immune response against the antigenic factor. In order to achieve these goals, novel vaccination techniques and an efficient adjuvant are required to render the vaccine immunogenically protective and trigger a strong immune response. Aim: Our study aims to promote and enhance the immunogenicity against RVF virus disease through lyophilized inactivated RVF vaccine through induction of early cellular, high and prolonged humeral immunity in vaccinated animals using cabopol as stabilizer and Saponin or normal saline as a diluent at time of vaccination. Moreover, manufacturing of these vaccines is easy to be done. Results: The gained results revealed that RVF freeze-dried vaccine with Carbopol that reconstituted using Saponin elicited better immune response than that reconstituted using normal saline (NaCl). The cell mediated immune response as represented by lymphocyte blastogenesis and phagocytic activity were markedly increased with high levels when we used Saponin as a diluent than that in group vaccinated with vaccine diluted with NaCl, on the other side the humeral immune response in group vaccinated using the Saponin as diluent is more detected and stayed within the protective level till the end of 11<sup>th</sup> month post vaccination (1.5 TCID<sub>50</sub>) while the immune response induced after using normal saline as a diluent stayed within the protective level till the end of 10<sup>th</sup> month post vaccination (1.8 TCID<sub>50</sub>). Conclusion: The use of Saponin as a diluent for reconstitution of the freeze dried RVF vaccine is preferable than the use of normal saline enhancing both sheep cellular and humeral immune response.展开更多
A new model is suggested for the history of the Baikal Rift, in deviation from the classic twostage evolution scenario, based on a synthesis of the available data from the Baikal Basin and revised correlation between ...A new model is suggested for the history of the Baikal Rift, in deviation from the classic twostage evolution scenario, based on a synthesis of the available data from the Baikal Basin and revised correlation between tectonic-lithological-stratigraphic complexes （TLSC） in sedimentary sections around Lake Baikal and seismic stratigraphic sequences （SSS） in the lake sediments. Unlike the previous models, the revised model places the onset of rifting during Late Cretaceous and comprises three major stages which are subdivided into several substages. The stages and the substages are separated by events of tectonic activity and stress reversal when additional compression produced folds and shear structures. The events that mark the stage boundaries show up as gaps, unconformities, and deformation features in the deposition patterns. The earliest Late Cretaceous-Oligocene stage began long before the India-Eurasia collision in a setting of diffuse extension that acted over a large territory of Asia. The NW-SE far-field pure extension produced an NE-striking half-graben oriented along an old zone of weakness at the edge of the Siberian craton. That was already the onset of rift evolution recorded in weathered lacustrine deposits on the Baikal shore and in a wedge-shaped acoustically transparent seismic unit in the lake sediments. The second stage spanning Late Oligocene-Early Pliocene time began with a stress change when the effect from the Eocene India-Eurasia collision had reached the region and became a major control of its geodynamics. The EW and NE transpression and shear from the collisional front transformed the Late Cretaceous half-graben into a U-shaped one which accumulated a deformed layered sequence of sediments. Rifting at the latest stage was driven by extension from a local source associated with hot mantle material rising to the base of the rifted crust. The asthenospheric upwarp first induced the growth of the Baikal dome and the related change from finer to coarser molasse deposition. With time, the upwarp became a more powerful stress source than the collision, and the stress vector returned to the previous NW-SE extension that changed the rift geometry back to a half-graben. The layered Late Pliocene-Quaternary subaerial tectonic--lithological-stratigraphic and the Quaternary submarine seismic stratigraphic units filling the latest haIf-graben remained almost undeformed. The rifting mechanisms were thus passive during two earlier stages and active during the third stage. The three-stage model of the rift history does not rule out the previous division into two major stages but rather extends its limits back into time as far as the Maastrichtian. Our model is consistent with geological, stratigraphic, structural, and geophysical data and provides further insights into the understanding of rifting in the Baikal region in particular and continental rifting in general.展开更多
The East African Rift system （EARS） provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches, the eastern, magma-rich, and the western, magma-poor, on either sides o...The East African Rift system （EARS） provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches, the eastern, magma-rich, and the western, magma-poor, on either sides of the old thick Tanzanian craton embedded in a younger lithosphere. Data on the pre-rifr, syn-rift and post-rift far-field volcanic and tectonic activity show that the EARS formed in the context of the interaction between a deep mantle plume and a horizontally and vertically heterogeneous lithosphere under far-field tectonic extension. We bring quantitative insights into this evolution by implementing high-resolution 3D thermo-mechanical numerical deformation models of a lithosphere of realistic rheology. The models focus on the central part of the EARS. We explore scenarios of plumelithosphere interaction with plumes of various size and initial position rising beneath a tectonically pre-stretched lithosphere. We test the impact of the inherited rheological discontinuities （suture zones） along the craton borders, of the rheological structure, of lithosphere plate thickness variations, and of physical and mechanical contrasts between the craton and the embedding lithosphere. Our experiments indicate that the ascending plume material is deflected by the cratonic keel and preferentially channeled along one of its sides, leading to the formation of a large rift zone along the eastern side of the craton, with significant magmatic activity and substantial melt amount derived from the mantle plume material. We show that the observed asymmetry of the central EARS, with coeval amagmatic （western） and magmatic （eastern） branches, can be explained by the splitting of warm material rising from a broad plume head whose initial position is slightly shifted to the eastern side of the craton. In that case, neither a mechanical weakness of the contact between the craton and the embedding lithosphere nor the presence of second plume are required to produce simulations that match observations. This result reconciles the passive and active rift models and demonstrates the possibility of development of both magmatic and amagmatic rifts in identical geotectonic environments.展开更多
The north trending rifts in southern Tibet represent the E-W extension of the plateau and confirming the initial rifting age is key to the study of mechanics of these rifts. Pagri-Duoqing Co graben is located at south...The north trending rifts in southern Tibet represent the E-W extension of the plateau and confirming the initial rifting age is key to the study of mechanics of these rifts. Pagri-Duoqing Co graben is located at southern end of Yadong-Gulu rift, where the late Cenozoic sediments is predominately composed of fluvio-lacustrine and moraine. Based on the sedimentary composition and structures, the fluviolacustrine could be divided into three facies, namely, lacustrine, lacustrine fan delta and alluvial fan. The presence of paleo-currents and conglomerate components and the provenance of the strata around the graben indicate that it was Tethys Himalaya and High Himalaya. Electron spin resonance(ESR) dating and paleo-magnetic dating suggest that the age of the strata ranges from ca. 1.2 Ma to ca. 8 Ma. Optically stimulated luminescence(OSL) dating showed that moraine in the graben mainly developed from around181-109 ka(late Middle Pleistocene). Combining previous data about the Late Cenozoic strata in other basins, it is suggested that 8-15 Ma may be the initial rifting time. Together with sediment distribution and drainage system, the sedimentary evolution of Pagri could be divided into four stages. The graben rifted at around 15-8 Ma due to the eastern graben-boundary fault resulting in the appearance of a paleolake.Following by a geologically quiet period about 8-2.5 Ma, the paleolake expanded from east to west at around 8-6 Ma reaching its maximum at ca. 6 Ma. Then, the graben was broken at about 2.5 Ma. At last,the development of the glacier separated the graben into two parts that were Pagri and Duoqing Co since the later stages of the Middle Pleistocene. The evolution process suggested that the former three stages were related to the tectonic movement, which determined the basement of the graben, while the last stage may have been influenced by glacial activity caused by climate change.展开更多
By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,...By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,multiple groups of faults developed in the rift due to the effect of tensile force,bringing about multiple mound and shoal belts controlled by horsts in the second member of the Sinian Dengying Formation;in the development stage of the rift,the boundary faults of the rift controlled the development of mound and shoal belts at the platform margin in the fourth member of Dengying Formation;during the shrinkage period of the rift,platform margin grain shoals of the Cambrian Canglangpu Formation developed in the rift margin.Second,four sets of large-scale mound and shoal reservoirs in the second member of Dengying Formation,the fourth member of Dengying Formation,Canglangpu Formation and Longwangmiao Formation overlap with several sets of source rocks such as Qiongzhusi Formation source rocks and Dengying Formation argillaceous limestone or dolomite developed inside and outside the rift,forming good source-reservoir-cap rock combinations;the sealing of tight rock layers in the lateral and updip direction results in the formation model of large lithologic gas reservoirs of oil pool before gas,continuous charging and independent preservation of each gas reservoir.Third,six favorable exploration zones of large-scale lithologic gas reservoirs have been sorted out through comprehensive evaluation,namely,mound and shoal complex controlled by horsts in the northern part of the rift in the second member of Dengying Formation,isolated karst mound and shoal complex of the fourth member of Dengying Formation in the south of the rift,the superimposed area of multi-stage platform margin mounds and shoals of the second and fourth members of Dengying Formation and Canglangpu Formation in the north slope area,the platform margin mounds and shoals of the second and fourth members of Dengying Formation in the west side of the rift,the platform margin mound and shoal bodies of the fourth member of Dengying Formation in the south slope area,etc.Fourth,Well Pengtan-1 drilled on the mound and shoal complex controlled by horsts of the second member of Dengying Formation in the rift and Well Jiaotan-1 drilled on the platform margin mound and shoal complex of the North Slope have obtained high-yield gas flows in multiple target layers,marking the discovery of a new gas province with reserves of(2-3)×10^(12) m^(3).This has proved the huge exploration potential of large lithologic gas reservoir group related to intracratonic rift.展开更多
The rift lake basins in the eastern China have abundant hydrocarbon resources of lithologic deposits, which resulted from excellent source rocks and multi-type sandbodies developed during strong rifting. Vertically, t...The rift lake basins in the eastern China have abundant hydrocarbon resources of lithologic deposits, which resulted from excellent source rocks and multi-type sandbodies developed during strong rifting. Vertically, the lithologic deposits are mainly distributed in the lowstand, lacustrine invasion and early highstand systems of third-order sequence corresponding to a secondary tectonic episode of strong rifting, and laterally they are closely related to various fans and turbidite sandbodies controlled by syn-sedimentary faults. A variety of lithologic traps have been developed in the rift lake basins, and they generally have favorable conditions of source-reservoir-seal assemblage and hydrocarbon accumulation dynamics, indicating that there is a great exploration potential of lithologic deposits in the rift lake basins. In order to obtain satisfactory effects of lithologic deposit exploration, it is required to combine new theories with advanced technical methods.展开更多
基金supported by grant D86-RALMI23CIVIE_01 awarded by the Italian Ministry of University and Research under the Program for Young Researchers“Rita Levi Montalcini”.
文摘A wide northeast-trending belt of intraplate alkaline volcanism,exhibiting similar geochemical characteristics,stretches from the Eastern Atlantic Ocean to the Cenozoic rift system in Europe.Its formation is associated with both passive and active mechanisms,but it remains a source of ongoing debate among geoscientists.Here,we show that seismic whole-mantle tomography models consistently identify two extensive low-velocity anomalies beneath the Canary Islands(CEAA)and Western-Central Europe(ECRA)at mid-mantle depths,merging near the core-mantle boundary.These low-velocity features are interpreted as two connected broad plumes originating from the top of the African LLSVP,likely feeding diapir-like upwellings in the upper mantle.The CEAA rises vertically,whereas the ECRA is tilted and dissipates at mantle transition zone depths,possibly due to the interaction with the cold Alpine subducted slab,which hinders its continuity at shallower depths.While plate-boundary forces are considered the primary drivers of rifting,the hypothesis that deep mantle plumes play a role in generating volcanic activity provides a compelling explanation for the European rift-related alkaline volcanism,supported by geological,geophysical,and geochemical evidence.
基金supported by the National Natural Science Foundation of China(Nos.42172109,41872113,42172108)China National Petroleum Corporation-China University of Petroleum(Beijing)strategic cooperation science and technology project(ZLZX2020-02)+2 种基金Science Foundation of China University of Petroleum(Beijing)(Nos.2462020BJRC002,2462020YXZZ020)Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX1166)Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202201511).
文摘Previous studies have indicated that sediment gravity flow deposits developed in lacustrine active extensional rift basins are primarily influenced by tectonics and to a lesser extent by climate.Our present work reveals that climate can obscure the effect of tectonic subsidence by regulating sediment supply;conversely,tectonics can impede the sedimentary manifestation of climatic impacts.Here a case study has been presented to assess the impact of climate-modulated rapid lake-level rise and tectonic subsidence on the development of coarse-grained gravity flow deposits in the Dongying rift margin of the Bohai Bay Basin,eastern China.The lithofacies analysis reveals frequent bed amalgamation,abundant thick massive coarse-grained deposits,widespread cross bedding and plant fragments,and incomplete composite bed formed by high-energy erosion,indicating that the hyperpycnal flow is an important mechanism driving the deposition of these coarse-grained sediments.Detailed sequence stratigraphic analysis and sediment dispersal pattern suggest that the long-striped nearshore subaqueous fan systems induced by outburst-flood hyperpycnal flow distributed along the border fault,are primarily controlled by long-term tectonics,while the rapid rise of lake level driven by short-term climate change possibly intensifies seasonal flood-generated hyperpycnal flow occurrences and consequently promotes the basinal fan progradation.The maximum scale of these coarse-grained gravity flow deposits of the basinal fan systems are typically attained during the transgressive systems tract,which deviates from the classical sequence stratigraphic model.Furthermore,it presented a continuous transition from the proximal to the distal part,encompassing traction flows and turbidity currents during the periods of relatively stable tectonics.Nevertheless,gravel-rich debris flows appear to predominate the dispersion of coarse-grained sediments during periods characterized by intense tectonic activity.The coarse-grained gravity flow deposits in the lacustrine rift margin reported here,challenge the traditional beliefs:this study suggests that subaqueous deposits abundantly preserved in the transgressive setting.
基金supported by the National Natural Science Foundation of China(No.24A20592).
文摘The Cambrian Qiongzhusi Formation in the Sichuan Basin harbors significant potential for shale gas harvesting.However,systematic disparities in mineral composition and reservoir architecture have been observed between intra-and extra-trough reservoirs within the Deyang-Anyue Rift Trough.These variations were primarily determined by divergences in the sedimentary environments developed during the evolution of the rift trough,which were a main factor in fostering the heterogeneous distribution of shale gas enrichment found today.However,the genetic mechanisms that govern reservoir heterogeneity across distinct structural domains(intra-trough,trough margin,and extra-trough)remain poorly understood,particularly regarding the coupling relationships between depositional environments,reservoir characteristics,and gas-bearing properties.This study adopts a multidisciplinary approach to investigating this issue that integrates core analysis,well-log interpretations,and geochemical data.Through systematic comparisons conducted using X-ray diffraction mineralogy,organic carbon quantification,and spontaneous imbibition experiments,we characterize the mineral assemblages,organic geochemical signatures,and pore structures found across the three structural domains of the Deyang-Anyue Rift Trough.The key findings are as follows:(1)The depositional environment is the main influence on reservoir distribution and organic matter enrichment,with intra-trough shales exhibiting a higher abundance of organic matter than their trough-margin and extra-trough counterparts.(2)Enhanced brittleness in intra-trough zones correlates with the predominance of biogenic silica therein.(3)Synergistic organic-inorganic interactions govern pore system development.(4)Gas-bearing capacity is jointly determined by effective porosity and organic matter content.These findings establish the rift trough as a preferential exploration target,providing critical geological guidance for optimizing shale gas exploration strategies in the Cambrian Qiongzhusi Formation.
基金supported by the Major National Science and Technology Programs of China(No.2016E-0202,No.QGYQZYPJ2022-1).
文摘In contrast to well-studied rift basins in NE China,the Hailar Basin has received relatively less attention regarding the combined patterns of different types of grabens and half-grabens.This study aims to explore whether the combined patterns of grabens in the Hailar Basin exhibit similar characteristics to those in other NE China rift basins and to identify the underlying causes.To achieve this,a comprehensive analysis of the major fault systems and the combined patterns of faulted sub-depressions,as well as their controlling mechanisms,was conducted.This analysis utilized the latest 3D seismic data that cover nearly the entire Beier Depression.Three groups of pre-existing fault systems were observed in the basement of the Beier Depression,and they are the NEE-EW-trending fault systems,the NE-trending fault systems,and the NW-trending fault systems.The NEE-EW-trending fault systems were distributed in the central part of the Beier Depression and primarily controlled the sedimentary filling of the Tongbomiao and the Lower Nantun Formations.The NE-trending fault systems were distributed in the southwestern part of the Beier Depression and primarily controlled the sedimentary filling of the Upper Nantun Formations.The NW-trending fault systems were distributed rarely in the Beier Depression.Five kinds of combined patterns of the sub-depressions were developed in the Beier Depression,and they are the parallel,en echelon,face-to-face,back-to-back,and S-shaped combined patterns.They were controlled by the NEE-EW-trending and the NE-trending fault systems with different orientations,arrangements,and activation sequences.
基金Supported by the National Science and Technology Major Project of China(2024ZD1400101)China National Key Research and Development Project(2022YFF0801204)Major Science and Technology Project of CNPC(2023ZZ15YJ01,2021DJ0702)。
文摘Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.
基金Supported by the National Natural Science Foundation of China(42272161)PetroChina Science and Technology Major Project(2023ZZ16)Research Institute of Exploration and Development,PetroChina Southwest Oil&Gasfield Company(2024D101-01-06)。
文摘Taking the natural gas reservoirs of the Sinian Dengying Formation on the east and west sides(Gaoshiti-Moxi area and north slope of central Sichuan paleo-uplift on the east;Weiyuan and Well Datan-1 block on the west)of the Deyang-Anyue rift trough in the Sichuan Basin,China,as the research object,the geochemical parameters(component,isotopic composition)of natural gas from the Dengying Formation in different areas are compared,and then the differences in geochemical characteristics of Dengying natural gas on the east and west sides of the Deyang-Anyue rift trough and their genesis are clarified.First,the Dengying gas reservoirs on both sides of the rift trough are predominantly composed of oil-cracking gas with high maturity,which is typical dry gas.Second,severely modified by thermochemical sulfate reduction(TSR)reaction,the Dengying gas reservoirs on the east side exhibit high H2S and CO_(2) contents,with an elevated δ^(13)C_(2) value(average value higher than-29‰).The Dengying gas reservoirs in the Weiyuan area are less affected by TSR modification,though the δ^(13)C_(1) values are slightly greater than that of the reservoirs on the east side with partial reversal of carbon isotope composition,likely due to the water-soluble gas precipitation and accumulation mechanism.The Dengying gas reservoir of Well Datan-1 shows no influence from TSR.Third,the Dengying gas reservoirs reflect high helium contents(significantly higher than that on the east side)in the Weiyuan and Datan-1 areas on the west side,which is supposed to attribute to the widespread granites in basement and efficient vertical transport along faults.Fourth,controlled by the paleo-salinity of water medium in the depositional period of the source rock,the δ^(2)HCH_(4) values of the Dengying gas reservoirs on the west side are slightly lighter than those on the east side.Fifth,the Dengying natural gas in the Datan-1 area is contributed by the source rocks of the Sinian Doushantuo Formation and the third member of the Dengying Formation,in addition to the Cambrian Qiongzhusi Formation.
基金Grants from the Program of Shanghai Academic Research Leader(22XD1420600)Shanghai Municipal Science and Technology Major Project(ZD2021CY001)+2 种基金National Natural Science Foundation of China(81974305)Shenzhen Medical Research Fund(SMRF No.B2302029)Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences(2023-PT310-02)supported this work.
文摘Rift Valley fever virus(RVFV)is a high-containment pathogen that causes severe diseases in humans,with no approved therapeutics available.Its classification as a biosafety level 3(BSL-3)agent has limited research and therapeutic development due to safety concerns.In this study,we developed a stable replicon cell line maintaining the replication of L and S genomic segments of RVFV.Single-cycle viral replicon particles(VRPs)could be efficiently packaged through trans-complementation of glycoproteins from different strains,recapitulating authentic viral entry and replication while minimizing biosafety risks.Using this system,we conducted high-throughput screening of a small-molecule compound library and identified CNX-1351 as an antiviral agent for multiple RNA viruses.Mechanistic studies revealed that CNX-1351 inhibits viral replication,potentially by targeting the PI3K-Akt signaling pathway.This single-cycle VRP system provides a valuable tool for studying RVFV biology,host interactions,antiviral and vaccine development under reduced biosafety constraints.
基金Supported by the National Science and Technology Major Project of China(2017ZX05009-002)National Natural Science Foundation of China(41772090)。
文摘Based on sedimentary characteristics of the fine-grained rocks of the lower submember of second member of the Lower Cretaceous Shahezi Formation(K_(1)sh_(2)^(L))in the Lishu rift depression,combined with methods of organic petrology,analysis of major and trace elements as well as biological marker compound,the enrichment conditions and enrichment model of organic matter in the fine-grained sedimentary rocks in volcanic rift lacustrine basin are investigated.The change of sedimentary paleoenvironment controls the vertical distribution of different lithofacies types in the K_(1)sh_(2)^(L)and divides it into the upper and lower parts.The lower part contains massive siliceous mudstone with bioclast-bearing siliceous mudstone,whereas the upper part is mostly composed of laminated siliceous shale and laminated fine-grained mixed shale.The kerogen types of organic matter in the lower and upper parts are typesⅡ_(2)–Ⅲand typesⅠ–Ⅱ_(1),respectively.The organic carbon content in the upper part is higher than that in the lower part generally.The enrichment of organic matter in volcanic rift lacustrine basin is subjected to three favorable conditions.First,continuous enhancement of rifting is the direct factor increasing the paleo-water depth,and the rise of base level leads to the expansion of deep-water mudstone/shale deposition range.Second,relatively strong underwater volcanic eruption and rifting are simultaneous,and such event can provide a lot of nutrients for the lake basin,which is conducive to the bloom of algae,resulting in higher productivity of typesⅠ–Ⅱ_(1)kerogen.Third,the relatively dry paleoclimate leads to a decrease in input of fresh water and terrestrial materials,including TypeⅢkerogen from terrestrial higher plants,resulting in a water body with higher salinity and anoxic stratification,which is more favorable for preservation of organic matter.The organic matter enrichment model of fine-grained sedimentary rocks of volcanic rift lacustrine basin is established,which is of reference significance to the understanding of the organic matter enrichment mechanism of fine-grained sedimentary rocks of Shahezi Formation in Songliao Basin and even in the northeast China.
基金Supported by the Strategic Research and Technical Consultation Project of Sinopec Science and Technology CommissionSinopec Major Science and Technology Project(P22037)。
文摘By benchmarking with the iteration of drilling technology,fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin,East China,the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development,drilling and fracturing technologies.The technology system supports the rapid growth of shale oil production and reduces the development investment cost.By comparing it with the shale oil development technology in the United States,the prospect of the shale oil development technology iteration in continental rift lake basins is proposed.It is suggested to continuously strengthen the overall three-dimensional development,improve the precision level of engineering technology,upgrade the engineering technical indicator system,accelerate the intelligent optimization of engineering equipment,explore the application of complex structure wells,form a whole-process integrated quality management system from design to implementation,and constantly innovate the concept and technology of shale oil development,so as to promote the realization of extensive,beneficial and high-quality development of shale oil in continental rift lake basins.
基金Supported by the National Natural Science Foundation Project(92255302)National Science and Technology Major Project(2016ZX05029005)Scientific Research and Technological Development Project of PetroChina(2021DJ31).
文摘Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.The study shows that the Central African Rift System mainly develops high-quality lacustrine source rocks in the Lower Cretaceous,and the West African Rift System mainly develops high-quality terrigenous organic matter-rich marine source rocks in the Upper Cretaceous,and the two types of source rocks provide a material basis for the enrichment of oil and gas in the CWARS.Multiple sets of reservoir rocks including fractured basement and three sets of regional cap rocks in the Lower Cretaceous,the Upper Cretaceous,and the Paleogene are developed in the CWARS.Since the Late Mesozoic,due to the geodynamic factors including the dextral strike-slip movement of the Central African Shear Zone,the basins in different directions of the CWARS differ in terms of rifting stages,intervals of regional cap rocks,trap types and accumulation models.The NE-SW trending basins have mainly preserved one stage of rifting in the Early Cretaceous,with regional cap rocks developed in the Lower Cretaceous strata,forming traps of reverse anticlines,flower-shaped structures and basement buried hill,and two types of hydrocarbon accumulation models of"source and reservoir in the same formation,and accumulation inside source rocks"and"up-source and down-reservoir,and accumulation below source rocks".The NW–SE basins are characterized by multiple rifting stages superimposition,with the development of regional cap rocks in the Upper Cretaceous and Paleogene,forming traps of draping anticlines,faulted anticlines,antithetic fault blocks and the accumulation model of"down-source and up-reservoir,and accumulation above source rocks".The combination of reservoir and cap rocks inside source rocks of basins with multiple superimposed rifting stages,as well as the lithologic reservoirs and the shale oil inside source rocks of strong inversion basins are important fields for future exploration in basins of the CWARS.
基金supported by the National Natural Science Foundation of China (Grant number 92255302)the Major Scientific and Technological Projects of China National Petroleum Corporation (No. 2023ZZ07)。
文摘It is essential to intensify research on the strike-slip tectonic system in West and Central Africa to better understand regional tectonic evolution and achieve future breakthroughs in oil and gas exploration.Based on the structural interpretation of extensive seismic data and stratigraphic paleontological analysis of more than 50 wells, this study investigated the tectonic history, sedimentary filling, and evolution of the rift basins in the West and Central Africa, and identified a novel type of intraplate strike-slip tectonic system. It exhibits the following characteristics:(i) the strike-slip tectonic system in the West and Central Africa consists of the Central African Shear Zone(CASZ) and two rift branches, manifesting as an N-shape;(ii) most of basins and rifts are characterized by rapid subsidence at one end and substantial sedimentary thickness;(iii) two types of strike-slip basins are developed, namely the transform-normal extensional basin(TEB) along CASZ and the strike-slip-induced extensional basin(SEB) at each end of CASZ;(iv) two types of basins display their own temporal and spatial evolution history. TEBs underwent two rifting stages during the Early and Late Cretaceous, with a strong inversion at the end of the Late Cretaceous. SEBs experienced three rifting stages, i.e., the Early Cretaceous, Late Cretaceous, and Paleogene, with a weak inversion;and(v) this strike-slip tectonic system was formed under intraplate divergent field, indicating a new type of system. This discovery enhances understanding of the breakup of Gondwana and provides valuable guidance for future oil and gas exploration.
文摘The Wadi Natash volcanic field(WNVF)in the south of the Eastern Desert of Egypt is a typical example of well-preserved intraplate alkaline magmatism during the Late Cretaceous,i.e.,prior to the Oligo-Miocene Red Sea rift.We compiled stratigraphic sections at two sectors;namely East Gabal Nuqra and West Khashm Natash(WKN)where the volcanic flows are intercalated with the Turonian Abu Agag sandstone with occasional paleosols when volcanic activity is intermittent.Peridotite mantle xenoliths are encountered in the first sector whereas flows in the second sector are interrupted by trachyte plugs and ring dykes.On a geochemical basis,the maifc melt originating from the lithospheric mantle beneath the WNVF practiced~5%partial melting of phlogopite-bearing garnet peridotite.Basalts dominate in the two sectors and highly evolved(silicic)rocks are confined to the WKN sector.Rejuvenation of ancient Precambrian fractures following the NW-SE and ENE-WSW trends facilitated the ascend of Late Cretaceous mantle-derived alkaline magma.Structurally,the WNVF developed at the eastern shoulder of the so-called"Kom Ombo-Nuqra-Kharit rift system"that represents a well-defined NW-trending intracontinental rift basin in the southern Eastern Desert.In such a structural setup,the Natash volcanic are confined to half-grabens at the East Gabal Nuqra sector whereas the West Khashm Natash sector is subjected to extensional stresses that propagated eastwards.The WNVF is a typical example of fluvial clastics(Turonian)intercalation with rift-related alkaline volcanic rocks in northeast Africa.
文摘The Mesoproterozoic rifts are developed in the Ordos Basin located in the western margin of the North China Plate.Based on the latest 3D seismic data and previous research results,this study intends to discuss the zonal differential deformation characteristics and genetic mechanism of the Mesoproterozoic rifts in the Ordos Basin.NE-trending rifts are developed in the Mesoproterozoic in the south-central Ordos Basin,the main part of which are located near the western margin of the North China Plate.NNW-trending rifts are developed in the north of the basin,while NW-NNW rifts in the Mesoproterozoic in Hangjinqi area.The genetic mechanism of the Mesoproterozoic rifts is related to regional extensional stress field,plate boundary conditions and internal preexisting structures.The main extensional stress direction strikes NWW-SSE(120°)in the western margin of the North China Plate,based on the forward rift trend of the northern Mesoproterozoic.In Hangjinqi area,the reactivation of the existing NWtrending Wulansu fault and NW-NW-trending Daolao fault,results in dextral shear stress field.The boundary between the western margin of the North China Plate and its adjacent plates forms a nearly NS-trending preexisting basement tectonic belt,which intersects with the NWW-SSE(120°)extensional stress at an acute angle of 60°.Therefore,the western margin of the North China Plate is formed by oblique normal faults under oblique extension.Due to the long time span of Columbia Supercontinent breakup(1.8e1.6 Ga),the oblique rift in the south-central Ordos Basin is formed under the continuous oblique extension at the western margin of the North China Plate.
文摘Background: Vaccinations for animals are crucial for food production, animal welfare, public health, and animal health. They are an affordable way to stop animal sickness, increase food production efficiency, and lessen or stop the spread of zoonotic diseases to humans. Animal vaccines that are both safe and efficacious are vital to modern culture. The vaccine should induce a strong, protective and prolonged immune response against the antigenic factor. In order to achieve these goals, novel vaccination techniques and an efficient adjuvant are required to render the vaccine immunogenically protective and trigger a strong immune response. Aim: Our study aims to promote and enhance the immunogenicity against RVF virus disease through lyophilized inactivated RVF vaccine through induction of early cellular, high and prolonged humeral immunity in vaccinated animals using cabopol as stabilizer and Saponin or normal saline as a diluent at time of vaccination. Moreover, manufacturing of these vaccines is easy to be done. Results: The gained results revealed that RVF freeze-dried vaccine with Carbopol that reconstituted using Saponin elicited better immune response than that reconstituted using normal saline (NaCl). The cell mediated immune response as represented by lymphocyte blastogenesis and phagocytic activity were markedly increased with high levels when we used Saponin as a diluent than that in group vaccinated with vaccine diluted with NaCl, on the other side the humeral immune response in group vaccinated using the Saponin as diluent is more detected and stayed within the protective level till the end of 11<sup>th</sup> month post vaccination (1.5 TCID<sub>50</sub>) while the immune response induced after using normal saline as a diluent stayed within the protective level till the end of 10<sup>th</sup> month post vaccination (1.8 TCID<sub>50</sub>). Conclusion: The use of Saponin as a diluent for reconstitution of the freeze dried RVF vaccine is preferable than the use of normal saline enhancing both sheep cellular and humeral immune response.
文摘A new model is suggested for the history of the Baikal Rift, in deviation from the classic twostage evolution scenario, based on a synthesis of the available data from the Baikal Basin and revised correlation between tectonic-lithological-stratigraphic complexes （TLSC） in sedimentary sections around Lake Baikal and seismic stratigraphic sequences （SSS） in the lake sediments. Unlike the previous models, the revised model places the onset of rifting during Late Cretaceous and comprises three major stages which are subdivided into several substages. The stages and the substages are separated by events of tectonic activity and stress reversal when additional compression produced folds and shear structures. The events that mark the stage boundaries show up as gaps, unconformities, and deformation features in the deposition patterns. The earliest Late Cretaceous-Oligocene stage began long before the India-Eurasia collision in a setting of diffuse extension that acted over a large territory of Asia. The NW-SE far-field pure extension produced an NE-striking half-graben oriented along an old zone of weakness at the edge of the Siberian craton. That was already the onset of rift evolution recorded in weathered lacustrine deposits on the Baikal shore and in a wedge-shaped acoustically transparent seismic unit in the lake sediments. The second stage spanning Late Oligocene-Early Pliocene time began with a stress change when the effect from the Eocene India-Eurasia collision had reached the region and became a major control of its geodynamics. The EW and NE transpression and shear from the collisional front transformed the Late Cretaceous half-graben into a U-shaped one which accumulated a deformed layered sequence of sediments. Rifting at the latest stage was driven by extension from a local source associated with hot mantle material rising to the base of the rifted crust. The asthenospheric upwarp first induced the growth of the Baikal dome and the related change from finer to coarser molasse deposition. With time, the upwarp became a more powerful stress source than the collision, and the stress vector returned to the previous NW-SE extension that changed the rift geometry back to a half-graben. The layered Late Pliocene-Quaternary subaerial tectonic--lithological-stratigraphic and the Quaternary submarine seismic stratigraphic units filling the latest haIf-graben remained almost undeformed. The rifting mechanisms were thus passive during two earlier stages and active during the third stage. The three-stage model of the rift history does not rule out the previous division into two major stages but rather extends its limits back into time as far as the Maastrichtian. Our model is consistent with geological, stratigraphic, structural, and geophysical data and provides further insights into the understanding of rifting in the Baikal region in particular and continental rifting in general.
基金co-funded by a U.S.National Science Foundation(Grant EAR-0538119)to E.Calaisthe Advanced ERC(Grant 290864 RHEOLITH)to E.Burov and A.Koptev+2 种基金the Royal Academy of Netherlands visiting professor grant to E.Burovthe UPMC visiting professor grant to S.Cloetinghperformed on the ERC-funded SGI Ulysse cluster of ISTEP
文摘The East African Rift system （EARS） provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches, the eastern, magma-rich, and the western, magma-poor, on either sides of the old thick Tanzanian craton embedded in a younger lithosphere. Data on the pre-rifr, syn-rift and post-rift far-field volcanic and tectonic activity show that the EARS formed in the context of the interaction between a deep mantle plume and a horizontally and vertically heterogeneous lithosphere under far-field tectonic extension. We bring quantitative insights into this evolution by implementing high-resolution 3D thermo-mechanical numerical deformation models of a lithosphere of realistic rheology. The models focus on the central part of the EARS. We explore scenarios of plumelithosphere interaction with plumes of various size and initial position rising beneath a tectonically pre-stretched lithosphere. We test the impact of the inherited rheological discontinuities （suture zones） along the craton borders, of the rheological structure, of lithosphere plate thickness variations, and of physical and mechanical contrasts between the craton and the embedding lithosphere. Our experiments indicate that the ascending plume material is deflected by the cratonic keel and preferentially channeled along one of its sides, leading to the formation of a large rift zone along the eastern side of the craton, with significant magmatic activity and substantial melt amount derived from the mantle plume material. We show that the observed asymmetry of the central EARS, with coeval amagmatic （western） and magmatic （eastern） branches, can be explained by the splitting of warm material rising from a broad plume head whose initial position is slightly shifted to the eastern side of the craton. In that case, neither a mechanical weakness of the contact between the craton and the embedding lithosphere nor the presence of second plume are required to produce simulations that match observations. This result reconciles the passive and active rift models and demonstrates the possibility of development of both magmatic and amagmatic rifts in identical geotectonic environments.
基金supported by National Natural foundation of China (grants No. 41571013)China Geology Survey project (grants No. DD20160268)
文摘The north trending rifts in southern Tibet represent the E-W extension of the plateau and confirming the initial rifting age is key to the study of mechanics of these rifts. Pagri-Duoqing Co graben is located at southern end of Yadong-Gulu rift, where the late Cenozoic sediments is predominately composed of fluvio-lacustrine and moraine. Based on the sedimentary composition and structures, the fluviolacustrine could be divided into three facies, namely, lacustrine, lacustrine fan delta and alluvial fan. The presence of paleo-currents and conglomerate components and the provenance of the strata around the graben indicate that it was Tethys Himalaya and High Himalaya. Electron spin resonance(ESR) dating and paleo-magnetic dating suggest that the age of the strata ranges from ca. 1.2 Ma to ca. 8 Ma. Optically stimulated luminescence(OSL) dating showed that moraine in the graben mainly developed from around181-109 ka(late Middle Pleistocene). Combining previous data about the Late Cenozoic strata in other basins, it is suggested that 8-15 Ma may be the initial rifting time. Together with sediment distribution and drainage system, the sedimentary evolution of Pagri could be divided into four stages. The graben rifted at around 15-8 Ma due to the eastern graben-boundary fault resulting in the appearance of a paleolake.Following by a geologically quiet period about 8-2.5 Ma, the paleolake expanded from east to west at around 8-6 Ma reaching its maximum at ca. 6 Ma. Then, the graben was broken at about 2.5 Ma. At last,the development of the glacier separated the graben into two parts that were Pagri and Duoqing Co since the later stages of the Middle Pleistocene. The evolution process suggested that the former three stages were related to the tectonic movement, which determined the basement of the graben, while the last stage may have been influenced by glacial activity caused by climate change.
基金Supported by the National Science and Technology Major Project(2016ZX05007-002)。
文摘By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,multiple groups of faults developed in the rift due to the effect of tensile force,bringing about multiple mound and shoal belts controlled by horsts in the second member of the Sinian Dengying Formation;in the development stage of the rift,the boundary faults of the rift controlled the development of mound and shoal belts at the platform margin in the fourth member of Dengying Formation;during the shrinkage period of the rift,platform margin grain shoals of the Cambrian Canglangpu Formation developed in the rift margin.Second,four sets of large-scale mound and shoal reservoirs in the second member of Dengying Formation,the fourth member of Dengying Formation,Canglangpu Formation and Longwangmiao Formation overlap with several sets of source rocks such as Qiongzhusi Formation source rocks and Dengying Formation argillaceous limestone or dolomite developed inside and outside the rift,forming good source-reservoir-cap rock combinations;the sealing of tight rock layers in the lateral and updip direction results in the formation model of large lithologic gas reservoirs of oil pool before gas,continuous charging and independent preservation of each gas reservoir.Third,six favorable exploration zones of large-scale lithologic gas reservoirs have been sorted out through comprehensive evaluation,namely,mound and shoal complex controlled by horsts in the northern part of the rift in the second member of Dengying Formation,isolated karst mound and shoal complex of the fourth member of Dengying Formation in the south of the rift,the superimposed area of multi-stage platform margin mounds and shoals of the second and fourth members of Dengying Formation and Canglangpu Formation in the north slope area,the platform margin mounds and shoals of the second and fourth members of Dengying Formation in the west side of the rift,the platform margin mound and shoal bodies of the fourth member of Dengying Formation in the south slope area,etc.Fourth,Well Pengtan-1 drilled on the mound and shoal complex controlled by horsts of the second member of Dengying Formation in the rift and Well Jiaotan-1 drilled on the platform margin mound and shoal complex of the North Slope have obtained high-yield gas flows in multiple target layers,marking the discovery of a new gas province with reserves of(2-3)×10^(12) m^(3).This has proved the huge exploration potential of large lithologic gas reservoir group related to intracratonic rift.
文摘The rift lake basins in the eastern China have abundant hydrocarbon resources of lithologic deposits, which resulted from excellent source rocks and multi-type sandbodies developed during strong rifting. Vertically, the lithologic deposits are mainly distributed in the lowstand, lacustrine invasion and early highstand systems of third-order sequence corresponding to a secondary tectonic episode of strong rifting, and laterally they are closely related to various fans and turbidite sandbodies controlled by syn-sedimentary faults. A variety of lithologic traps have been developed in the rift lake basins, and they generally have favorable conditions of source-reservoir-seal assemblage and hydrocarbon accumulation dynamics, indicating that there is a great exploration potential of lithologic deposits in the rift lake basins. In order to obtain satisfactory effects of lithologic deposit exploration, it is required to combine new theories with advanced technical methods.
