The westerly extension of the Dras volcanics in the Deosai plateau of Baltistan, northern Pakistan, lying east of the Nanga Parbat—Haramosh Massif, is comprised of agglomerates and tuffs together with flows consistin...The westerly extension of the Dras volcanics in the Deosai plateau of Baltistan, northern Pakistan, lying east of the Nanga Parbat—Haramosh Massif, is comprised of agglomerates and tuffs together with flows consisting of basalt, andesite and some rhyolite. In the filed these volcanics are overlying the Ladakh batholith and both these basic and acidic suites of rocks carry the signatures of the Nanga Parbat—related orogeny. The flows appear to have evolved from a basaltic magma, with opaque oxide, clinopyroxene, hornblende and plagioclase, respectively appearing on the liquidus. These have been metamorphosed under greenschist facies conditions and may contain abundant epidote, chlorite and secondary amphibole. Metamorphic impact seems to be stronger in the west, i.e., in the vicinity of Nanga Parbat—Haramosh Massif, than in the East. An 40 Ar/ 39 Ar age of (125 4±6)Ma on hornblende phenocrysts in an andesite is in agreement with the Late Jurassic to Cretaceous age of the Dras volcanics, in India, and indicates that Nanga Parbat related tectonics may have played a part in the growth of lower green schist facies assemblage of the volcanic rocks.展开更多
Geological materials,both natural and processed, such as volcanics and ceramics(made of clay),has qualities such as positive charge on the surface,strong hydrophilicity,high specific surface area,high porosity,which a...Geological materials,both natural and processed, such as volcanics and ceramics(made of clay),has qualities such as positive charge on the surface,strong hydrophilicity,high specific surface area,high porosity,which are in favor of not only microorganism contacting and forming biofilm,but also the oxygen enrichment as well as the mass transfer process of nutriment and garbage produced by metabolism.展开更多
Triaxial creep tests were carried out under seepage pressure by using rock servo-controlled triaxial rheology testing equipment. Based on experimental results, rock rheological properties influenced by seepage-stress ...Triaxial creep tests were carried out under seepage pressure by using rock servo-controlled triaxial rheology testing equipment. Based on experimental results, rock rheological properties influenced by seepage-stress coupling were studied, and variations of seepage rate with time in complete creep processes of rock were analyzed. It is shown that, when the applied stress is less than failure stress level, the creep deformation is not obvious, and its main form is steady-state creep. When applied stress level is greater than or less than but close to fracture stress, it is easier to see the increase of creep deformation and the more obvious accelerative creep characteristics. The circumferential creep deformation is obviously higher than the axial creep deformation. At the stage of steady-state creep, the average of seepage flow rate is about 4.7×10-9 rn/s at confining pressure （tr3） of 2 MPa, and is about 3.9×10-9 m/s at a3 of 6 MPa. It is seen that the seepage flow rate at or3 of 2 MPa in this case is obviously larger than that at tr3 of 6 MPa. At the stage of creep acceleration, the seepage flow rate is markedly increased with the increase of time. The variation of rock permeability is directly connected to the growth and evolution of creep crack. It is suggested that the permeability coefficient in complete creep processes of rock is not a constant, but is a function of rock creep strain, confining pressure, damage variable and pore water pressure. The results can be considered to provide a reliable reference for the establishment of rock rheological model and parameter identification.展开更多
Yingcheng Formation is a set of volcanic strata composed of lava rocks,volcanic clastic rocks and sedimentary rocks,filled in some fault depressions in Songliao Basin,early Cretaceous.The study about litho-facies succ...Yingcheng Formation is a set of volcanic strata composed of lava rocks,volcanic clastic rocks and sedimentary rocks,filled in some fault depressions in Songliao Basin,early Cretaceous.The study about litho-facies succession of Yingcheng Formation in the outcropped area of the southeast margin and in Xujiaweizi fault depression and its distribution based on analysis of seismic data,shows that the sequence of volcanic strata is quite different from the clastic sedimentary sequence.To study the architecture of volcanic sequence and its structural control of Yingcheng Formation in Songliao Basin,in this work,dividing of the volcanic sequence and dating of the sequence boundaries were finished firstly,then displacement and displacement rate of faults were calculated.The results show that,sample ages of top of the first member,the seconde member,and the third member are 127 Ma,115 Ma,110.7 Ma,respectively and sample age of the bottom of the third member is 114.7 Ma.The maximum displacement and displacement rate of the fault 1 are 3 km and 300 m/Ma,respectively,and those of the fault 2 are 3 km and 1000 m/Ma.Studies suggest that,the cooling unit of lava rock or pyroclastic rock is a basic genetic stratigraphic unit in volcanic sequence stratigraphy.Cooling units can construct a parasequence reflecting a volcanic eruption stage.A sequence was superimposed by some parasequences,responding to a volcanic active cycle.There are three types of volcanic sequences in Yingcheng Formation: type of explosion,type of effusion and type of mixed explosion-effusion.The surface of the volcanic sequence,an unconformity surface widely spread and traced in seismic profiles,is a base for analysis of volcanic sequence.The development of volcanic sequence was controlled by faulting,and the curves of fault displacement(rate)can reflect this control.The preservation of volcanic sequence was controlled by the type of volcanic structure and the regional subsidence,also different from that of the sedimentary.The type of volcanic structure of Xujiaweizi was a volcanic depression during the forming of Yingcheng Formation,and the breakdowns of volcanoes and structural subsidence were key factors in the volcanic sequences preservation.展开更多
Based on the drilling,cores,logs,seismic,laboratory analysis and so on,reservoir characteristics and hydrocarbon accumulation of Carboniferous volcanic weathered crust in Zhongguai high area are studied.Volcanic rocks...Based on the drilling,cores,logs,seismic,laboratory analysis and so on,reservoir characteristics and hydrocarbon accumulation of Carboniferous volcanic weathered crust in Zhongguai high area are studied.Volcanic rocks were formed in an island arc environment.The lithology is mainly andesite and tuff;Reservoir spaces are mainly secondary pore,fracture and their combination forms,fractures have a better effect on reservoir seepage;There are four layer structures of volcanic weathered crust,weathered clay layer,strongly weathered zone,weakly weathered zone and unweathered zone and strongly weathered zone is the best,which is the main reservoir development zone;The development of reservoir is mainly affected by weathering-leaching,lithology and lithofacies,and fault(fracture);Effective reservoirs could reach to 480 m thickness(high quality reservoirs are within 240 m).Carboniferous volcanic reservoirs are distributed along three zones,which are near the fault zone,high structural part,favorable lithofacies development zone,and one plane,which is near the unconformity.展开更多
Polymetallic iron ore sulphate deposits of marine volcanic rock have been developed in the Fangniugou area,Jilin Province,China,but the division of volcanic ore-bearing strata has not been specifically elucidated and ...Polymetallic iron ore sulphate deposits of marine volcanic rock have been developed in the Fangniugou area,Jilin Province,China,but the division of volcanic ore-bearing strata has not been specifically elucidated and there is disagreement about the division.The sampling and SHRIMP U-Pb zircon dating of volcanic rock for Daheishan in the Fangniugou area and the northeast slope of the Duanjiadian were described.The volcanic rock formation period and recorded the volcanic events in the Daheishan mountains were systematically researched.Two samples of high-precision U-Pb zircon dating were used to represent the volcanic rock fomation period of the Late Silurian.The measured data reflect that multiple volcanic activities occurred during the Middle Silurian,Early Silurian,Middle Ordovician and Silurian,and Late Ordovician,probably matching volcanic events in the Songnan Basin identified from zircon dating.At the same time,it is confirmed that a controversial "conglomerate of Daheishan" did in fact develop in the Late Silurian,and those sections of both the Dazigou and Xinlitun-Taoshan with graptolite had been reversed.展开更多
Predicting high-quality volcanic reservoirs is one of the key issues for oil and gas exploration in the Songnan gas field.Core,seismic,and measurement data were used to study the lithologies,facies,reservoir porosity,...Predicting high-quality volcanic reservoirs is one of the key issues for oil and gas exploration in the Songnan gas field.Core,seismic,and measurement data were used to study the lithologies,facies,reservoir porosity,and reservoir types of the volcanic rocks in the Songnan gas field.The primary controlling factors and characteristics of the high-quality volcanic reservoirs of the Yingcheng Formation in the Songnan gas field were investigated,including the volcanic eruptive stage,edifice,edifice facies,cooling unit,lithology,facies,and diagenesis.Stages with more volatile content can form more high-quality reservoirs.The effusive rhyolite,explosive tuff,and tuff lava that formed in the crater,near-crater,and proximal facies and in the high-volatility cooling units of large acidic-lava volcanic edifices are the most favorable locations for the development of the high-quality reservoirs in the Songnan gas field.Diagenesis dissolution,which is controlled by tectonic action,can increase the size of secondary pores in reservoirs.Studying the controlling factors of the high-quality reservoirs can provide a theoretical basis for the prediction and analysis of high-quality volcanic reservoirs.展开更多
Distribution of heavy, light and clay minerals in Late Pleistocene—Holocene deposits from different coastal environments (beaches, lagoons, dunes, relict lakes, ria bays and inlets, open inlets) was analysed. It was ...Distribution of heavy, light and clay minerals in Late Pleistocene—Holocene deposits from different coastal environments (beaches, lagoons, dunes, relict lakes, ria bays and inlets, open inlets) was analysed. It was established that mineralogical composition of coastal deposits was a result of provenance and its hypergenous changes, transformation of material within transit zone, and accumulative conditions of inshore zone. Contents of stable minerals increase in deposits of the inlets confined to mouths of the small streams and in horizons of the sections, formed during regressive phases. Unstable minerals amount is higher in deposits of inlets, confined to mouths of the large river. The clay mineral fraction of shelf sediments consists mostly of illite. Authigenous pyrites dominate in deposits of ria bays, lagoons and relict lakes, formed during transgressive phases. Volcanic glass, found in deposits, is product of Holocene eruptions of Baegdusan (Baitushen) Volcano.展开更多
It is known that large amounts of Cenozoic high potassium volcanic rocks occur on the Tibetan plateau. The question is where do those high potassium magmas come from? Since the plateau is being compressed by subductio...It is known that large amounts of Cenozoic high potassium volcanic rocks occur on the Tibetan plateau. The question is where do those high potassium magmas come from? Since the plateau is being compressed by subduction and collision from the surrounding continents,it is a puzzle for us what is the formational environment and tectonic setting of these volcanic rocks? In particular,what is the relationship between these special rocks and formation and uplift of the plateau? We recently carried out an investigation on these Cenozoic volcanic rocks in Hoh Xil,northern Tibetan plateau,including volcanic rocks in the Jingyuhu,Xiongyingtai and Shuangquanzi areas. In the region,some older lava flows occur as thick sheets with a flat surface and weathering crust; while some relatively younger lavas remain a relict volcanic cone or vent. Most of the relict cones are small (<100m in diameter) and some are over hundred meters,distributed along faults,particular strike\|slip fault,e.g.,East Kunlun strike slip fault. Relatively,intermediate\|acid volcanic rocks are prominent,and basic\|intermediate and acid are subordinate. Petrological and geochemical results show that these volcanic rocks have many common affinities,characterized by high contents of w (K 2O)+ w (Na 2O) (about 8%),and w (K\-2O)/ w (Na\-2O)>1 or close to 1,and mostly belonged to shoshonite\|trachyte association and some to ultra\|potassic rocks. The K\|Ar dating of whole rock and mica shows that the volcanism lasts from middle Miocene (15 47Ma) to Pleistocene (0 69Ma); they are 0 69Ma,13 77Ma and 15 47Ma in Jingyuhu; 11 05Ma,12 22Ma and 12 83Ma in Xiongyingai,; 1 58Ma,2 24Ma,5 23Ma,5 85Ma,8 20Ma,8 41Ma and 10 67Ma in Shuangquanzi.Two types of xenolith and xenocryst were found in Jingyuhu and Xiongyingtai,i.e..,crustal xenolith and mantle xenocryst.展开更多
Based on the data from typical core sampling, combined with K Ar dating, petrochemistry ,trace elemental geochemistry and isotopic compositions of the Mesozoic Cenozoic volcanic rock in the Huanghua basin, Bohai regio...Based on the data from typical core sampling, combined with K Ar dating, petrochemistry ,trace elemental geochemistry and isotopic compositions of the Mesozoic Cenozoic volcanic rock in the Huanghua basin, Bohai region, the geochemical features of the volcanic rock were studied. The rocks fall into four groups: Cenozoic basalt,Mesozoic late Cretaceous basaltic trachy andesite, Mesozoic late Cretaceous trachy dacite and liparite,and Mesozoic early Triassic dacite. The distribution pattern of the main elemental abundance of late Mesozoic shows a typical bimodal.Chronologically,for the volcanic rock,the amount of SiO 2 decreases gradually,the contents of Fe 2O 3,FeO,CaO,MgO,TiO 2,P 2O 5 and MnO increase little by little.The Cenozoic basalt is derived from the asthenospheric mantle.The late Cretaceous basaltic trachy andesite is derived from the enriched lithospheric mantle.In late Cretaceous and early Palaeogene,the felsic volcanic rock may be derived from fractional melting of the crust.展开更多
The aim of this work is to establish volcanic seismic reflection configuration models in the rift basins of Northeast China from a new perspective,the volcanostratigraphic structure.Accordingly,the volcanostratigraphi...The aim of this work is to establish volcanic seismic reflection configuration models in the rift basins of Northeast China from a new perspective,the volcanostratigraphic structure.Accordingly,the volcanostratigraphic structure of an outcrop near the Hailaier Rift Basin was analyzed to understand the characteristics and causal factors of physical boundaries.Further,3D seismic reflection data and analysis of deep boreholes in the Songliao Rift Basin were used to establish the relationship between volcanic seismic reflection configurations and volcanostratigraphic structures.These studies suggested that in volcanic successions,physical boundaries coincide with volcanic boundaries,and their distributions are controlled by the stacking patterns of volcanic units.Therefore,volcanic seismic reflection configurations can be interpreted in terms of the stacking patterns of volcanic units.These are also referred to as general bedding patterns in volcanostratigraphy.Furthermore,four typical seismic reflection configurations were identified,namely,the chaotic,the parallel continuous,the hummocky,the multi-mound superimposed and the composite.The corresponding interpretation models comprised single massive unit,vertical,intersectional,lateral multi-mound,and composite stacking patterns.The hummocky and composite reflection configurations with intersectional and composite stacking patterns are the most favorable for the exploration of volcanic reservoirs in rift basins.展开更多
Chatkal-Kurama region is characterized by igneous complexes of rocks with different composition. According to the existing data magmatism can be referred to 3 types:a) subductional（C<sub>1</sub>-C<sub&...Chatkal-Kurama region is characterized by igneous complexes of rocks with different composition. According to the existing data magmatism can be referred to 3 types:a) subductional（C<sub>1</sub>-C<sub>3</sub>）;b) orogenical（P<sub>1</sub>-T<sub>1</sub>）;and c) dyke（P<sub>2</sub>-T<sub>1</sub>-K）.Different ore deposits occurrences are connected with these rock complexes of Chatkal-Kurama region.展开更多
The emergence of the Qing—Zang plateau is among the most important geological events on the globe since the Cenozoic Era. Many geological issues can find answer from here. The major issues concerning plateau probably...The emergence of the Qing—Zang plateau is among the most important geological events on the globe since the Cenozoic Era. Many geological issues can find answer from here. The major issues concerning plateau probably have three: (1) geodynamics, timing and speed of the plateau uplift;(2) The plateau uplift impact on surrounding environment;(3) mineral resources in the plateau. The authors want to focuses on first issue based on volcanisms occurred in interior and surrounding of the plateau, The new opinions are following:(1) Each volcanic eruptive episode corresponded to strong uplift stage;(2) The dynamic mechanism of the plateau uplift can not ignore another force from west beyond collision between Indian and Eurasia plates from South;(3) The surrounding volcanic chain is not only related to the collision from South, but also from west.展开更多
文摘The westerly extension of the Dras volcanics in the Deosai plateau of Baltistan, northern Pakistan, lying east of the Nanga Parbat—Haramosh Massif, is comprised of agglomerates and tuffs together with flows consisting of basalt, andesite and some rhyolite. In the filed these volcanics are overlying the Ladakh batholith and both these basic and acidic suites of rocks carry the signatures of the Nanga Parbat—related orogeny. The flows appear to have evolved from a basaltic magma, with opaque oxide, clinopyroxene, hornblende and plagioclase, respectively appearing on the liquidus. These have been metamorphosed under greenschist facies conditions and may contain abundant epidote, chlorite and secondary amphibole. Metamorphic impact seems to be stronger in the west, i.e., in the vicinity of Nanga Parbat—Haramosh Massif, than in the East. An 40 Ar/ 39 Ar age of (125 4±6)Ma on hornblende phenocrysts in an andesite is in agreement with the Late Jurassic to Cretaceous age of the Dras volcanics, in India, and indicates that Nanga Parbat related tectonics may have played a part in the growth of lower green schist facies assemblage of the volcanic rocks.
文摘Geological materials,both natural and processed, such as volcanics and ceramics(made of clay),has qualities such as positive charge on the surface,strong hydrophilicity,high specific surface area,high porosity,which are in favor of not only microorganism contacting and forming biofilm,but also the oxygen enrichment as well as the mass transfer process of nutriment and garbage produced by metabolism.
基金Projects(11172090,51009052,51109069) supported by the National Natural Science Foundation of ChinaProject(2011CB013504) supported by the National Basic Research Program of China
文摘Triaxial creep tests were carried out under seepage pressure by using rock servo-controlled triaxial rheology testing equipment. Based on experimental results, rock rheological properties influenced by seepage-stress coupling were studied, and variations of seepage rate with time in complete creep processes of rock were analyzed. It is shown that, when the applied stress is less than failure stress level, the creep deformation is not obvious, and its main form is steady-state creep. When applied stress level is greater than or less than but close to fracture stress, it is easier to see the increase of creep deformation and the more obvious accelerative creep characteristics. The circumferential creep deformation is obviously higher than the axial creep deformation. At the stage of steady-state creep, the average of seepage flow rate is about 4.7×10-9 rn/s at confining pressure （tr3） of 2 MPa, and is about 3.9×10-9 m/s at a3 of 6 MPa. It is seen that the seepage flow rate at or3 of 2 MPa in this case is obviously larger than that at tr3 of 6 MPa. At the stage of creep acceleration, the seepage flow rate is markedly increased with the increase of time. The variation of rock permeability is directly connected to the growth and evolution of creep crack. It is suggested that the permeability coefficient in complete creep processes of rock is not a constant, but is a function of rock creep strain, confining pressure, damage variable and pore water pressure. The results can be considered to provide a reliable reference for the establishment of rock rheological model and parameter identification.
基金Project(40972074)supported by the National Natural Science Foundation of China
文摘Yingcheng Formation is a set of volcanic strata composed of lava rocks,volcanic clastic rocks and sedimentary rocks,filled in some fault depressions in Songliao Basin,early Cretaceous.The study about litho-facies succession of Yingcheng Formation in the outcropped area of the southeast margin and in Xujiaweizi fault depression and its distribution based on analysis of seismic data,shows that the sequence of volcanic strata is quite different from the clastic sedimentary sequence.To study the architecture of volcanic sequence and its structural control of Yingcheng Formation in Songliao Basin,in this work,dividing of the volcanic sequence and dating of the sequence boundaries were finished firstly,then displacement and displacement rate of faults were calculated.The results show that,sample ages of top of the first member,the seconde member,and the third member are 127 Ma,115 Ma,110.7 Ma,respectively and sample age of the bottom of the third member is 114.7 Ma.The maximum displacement and displacement rate of the fault 1 are 3 km and 300 m/Ma,respectively,and those of the fault 2 are 3 km and 1000 m/Ma.Studies suggest that,the cooling unit of lava rock or pyroclastic rock is a basic genetic stratigraphic unit in volcanic sequence stratigraphy.Cooling units can construct a parasequence reflecting a volcanic eruption stage.A sequence was superimposed by some parasequences,responding to a volcanic active cycle.There are three types of volcanic sequences in Yingcheng Formation: type of explosion,type of effusion and type of mixed explosion-effusion.The surface of the volcanic sequence,an unconformity surface widely spread and traced in seismic profiles,is a base for analysis of volcanic sequence.The development of volcanic sequence was controlled by faulting,and the curves of fault displacement(rate)can reflect this control.The preservation of volcanic sequence was controlled by the type of volcanic structure and the regional subsidence,also different from that of the sedimentary.The type of volcanic structure of Xujiaweizi was a volcanic depression during the forming of Yingcheng Formation,and the breakdowns of volcanoes and structural subsidence were key factors in the volcanic sequences preservation.
基金Project (51674211) supported by the National Natural Science Foundation of ChinaProject (51534006) supported by the Key Projects of the Natural Science Foundation,ChinaProject (2017ZX05036003-003) supported by the National Science and Technology Project of China
文摘Based on the drilling,cores,logs,seismic,laboratory analysis and so on,reservoir characteristics and hydrocarbon accumulation of Carboniferous volcanic weathered crust in Zhongguai high area are studied.Volcanic rocks were formed in an island arc environment.The lithology is mainly andesite and tuff;Reservoir spaces are mainly secondary pore,fracture and their combination forms,fractures have a better effect on reservoir seepage;There are four layer structures of volcanic weathered crust,weathered clay layer,strongly weathered zone,weakly weathered zone and unweathered zone and strongly weathered zone is the best,which is the main reservoir development zone;The development of reservoir is mainly affected by weathering-leaching,lithology and lithofacies,and fault(fracture);Effective reservoirs could reach to 480 m thickness(high quality reservoirs are within 240 m).Carboniferous volcanic reservoirs are distributed along three zones,which are near the fault zone,high structural part,favorable lithofacies development zone,and one plane,which is near the unconformity.
基金Project(2009GYXQ02-06) supported by the National Oil and Gas Resources of Strategic Project Selection Survey and Evaluation Fund from Land and Natural Resources Ministry,ChinaProject(2652013099) supported by the Fundamental Research Funds of Central Universities,China
文摘Polymetallic iron ore sulphate deposits of marine volcanic rock have been developed in the Fangniugou area,Jilin Province,China,but the division of volcanic ore-bearing strata has not been specifically elucidated and there is disagreement about the division.The sampling and SHRIMP U-Pb zircon dating of volcanic rock for Daheishan in the Fangniugou area and the northeast slope of the Duanjiadian were described.The volcanic rock formation period and recorded the volcanic events in the Daheishan mountains were systematically researched.Two samples of high-precision U-Pb zircon dating were used to represent the volcanic rock fomation period of the Late Silurian.The measured data reflect that multiple volcanic activities occurred during the Middle Silurian,Early Silurian,Middle Ordovician and Silurian,and Late Ordovician,probably matching volcanic events in the Songnan Basin identified from zircon dating.At the same time,it is confirmed that a controversial "conglomerate of Daheishan" did in fact develop in the Late Silurian,and those sections of both the Dazigou and Xinlitun-Taoshan with graptolite had been reversed.
基金Project(2009CB219306)supported by the National Basic Research Program of ChinaProject supported by the Key-Lab for Evolution of Past Lift and Environment in Northeast Asia,Ministry of Education,China+1 种基金Project supported by the third-phase Project 211 at Jilin University,ChinaProject supported by the Basic Research Fund of the Ministry of Education in 2009(Innovation Team Development Program,Jilin University)
文摘Predicting high-quality volcanic reservoirs is one of the key issues for oil and gas exploration in the Songnan gas field.Core,seismic,and measurement data were used to study the lithologies,facies,reservoir porosity,and reservoir types of the volcanic rocks in the Songnan gas field.The primary controlling factors and characteristics of the high-quality volcanic reservoirs of the Yingcheng Formation in the Songnan gas field were investigated,including the volcanic eruptive stage,edifice,edifice facies,cooling unit,lithology,facies,and diagenesis.Stages with more volatile content can form more high-quality reservoirs.The effusive rhyolite,explosive tuff,and tuff lava that formed in the crater,near-crater,and proximal facies and in the high-volatility cooling units of large acidic-lava volcanic edifices are the most favorable locations for the development of the high-quality reservoirs in the Songnan gas field.Diagenesis dissolution,which is controlled by tectonic action,can increase the size of secondary pores in reservoirs.Studying the controlling factors of the high-quality reservoirs can provide a theoretical basis for the prediction and analysis of high-quality volcanic reservoirs.
文摘Distribution of heavy, light and clay minerals in Late Pleistocene—Holocene deposits from different coastal environments (beaches, lagoons, dunes, relict lakes, ria bays and inlets, open inlets) was analysed. It was established that mineralogical composition of coastal deposits was a result of provenance and its hypergenous changes, transformation of material within transit zone, and accumulative conditions of inshore zone. Contents of stable minerals increase in deposits of the inlets confined to mouths of the small streams and in horizons of the sections, formed during regressive phases. Unstable minerals amount is higher in deposits of inlets, confined to mouths of the large river. The clay mineral fraction of shelf sediments consists mostly of illite. Authigenous pyrites dominate in deposits of ria bays, lagoons and relict lakes, formed during transgressive phases. Volcanic glass, found in deposits, is product of Holocene eruptions of Baegdusan (Baitushen) Volcano.
文摘It is known that large amounts of Cenozoic high potassium volcanic rocks occur on the Tibetan plateau. The question is where do those high potassium magmas come from? Since the plateau is being compressed by subduction and collision from the surrounding continents,it is a puzzle for us what is the formational environment and tectonic setting of these volcanic rocks? In particular,what is the relationship between these special rocks and formation and uplift of the plateau? We recently carried out an investigation on these Cenozoic volcanic rocks in Hoh Xil,northern Tibetan plateau,including volcanic rocks in the Jingyuhu,Xiongyingtai and Shuangquanzi areas. In the region,some older lava flows occur as thick sheets with a flat surface and weathering crust; while some relatively younger lavas remain a relict volcanic cone or vent. Most of the relict cones are small (<100m in diameter) and some are over hundred meters,distributed along faults,particular strike\|slip fault,e.g.,East Kunlun strike slip fault. Relatively,intermediate\|acid volcanic rocks are prominent,and basic\|intermediate and acid are subordinate. Petrological and geochemical results show that these volcanic rocks have many common affinities,characterized by high contents of w (K 2O)+ w (Na 2O) (about 8%),and w (K\-2O)/ w (Na\-2O)>1 or close to 1,and mostly belonged to shoshonite\|trachyte association and some to ultra\|potassic rocks. The K\|Ar dating of whole rock and mica shows that the volcanism lasts from middle Miocene (15 47Ma) to Pleistocene (0 69Ma); they are 0 69Ma,13 77Ma and 15 47Ma in Jingyuhu; 11 05Ma,12 22Ma and 12 83Ma in Xiongyingai,; 1 58Ma,2 24Ma,5 23Ma,5 85Ma,8 20Ma,8 41Ma and 10 67Ma in Shuangquanzi.Two types of xenolith and xenocryst were found in Jingyuhu and Xiongyingtai,i.e..,crustal xenolith and mantle xenocryst.
基金The National Natural Science Foundation of China !(No .492 5 2 0 0 1)
文摘Based on the data from typical core sampling, combined with K Ar dating, petrochemistry ,trace elemental geochemistry and isotopic compositions of the Mesozoic Cenozoic volcanic rock in the Huanghua basin, Bohai region, the geochemical features of the volcanic rock were studied. The rocks fall into four groups: Cenozoic basalt,Mesozoic late Cretaceous basaltic trachy andesite, Mesozoic late Cretaceous trachy dacite and liparite,and Mesozoic early Triassic dacite. The distribution pattern of the main elemental abundance of late Mesozoic shows a typical bimodal.Chronologically,for the volcanic rock,the amount of SiO 2 decreases gradually,the contents of Fe 2O 3,FeO,CaO,MgO,TiO 2,P 2O 5 and MnO increase little by little.The Cenozoic basalt is derived from the asthenospheric mantle.The late Cretaceous basaltic trachy andesite is derived from the enriched lithospheric mantle.In late Cretaceous and early Palaeogene,the felsic volcanic rock may be derived from fractional melting of the crust.
基金Projects(41472304,41430322) supported by the National Natural Science Foundation of ChinaProject(2012CB822002) supported by National Major State Basic Research Program of China
文摘The aim of this work is to establish volcanic seismic reflection configuration models in the rift basins of Northeast China from a new perspective,the volcanostratigraphic structure.Accordingly,the volcanostratigraphic structure of an outcrop near the Hailaier Rift Basin was analyzed to understand the characteristics and causal factors of physical boundaries.Further,3D seismic reflection data and analysis of deep boreholes in the Songliao Rift Basin were used to establish the relationship between volcanic seismic reflection configurations and volcanostratigraphic structures.These studies suggested that in volcanic successions,physical boundaries coincide with volcanic boundaries,and their distributions are controlled by the stacking patterns of volcanic units.Therefore,volcanic seismic reflection configurations can be interpreted in terms of the stacking patterns of volcanic units.These are also referred to as general bedding patterns in volcanostratigraphy.Furthermore,four typical seismic reflection configurations were identified,namely,the chaotic,the parallel continuous,the hummocky,the multi-mound superimposed and the composite.The corresponding interpretation models comprised single massive unit,vertical,intersectional,lateral multi-mound,and composite stacking patterns.The hummocky and composite reflection configurations with intersectional and composite stacking patterns are the most favorable for the exploration of volcanic reservoirs in rift basins.
文摘Chatkal-Kurama region is characterized by igneous complexes of rocks with different composition. According to the existing data magmatism can be referred to 3 types:a) subductional（C<sub>1</sub>-C<sub>3</sub>）;b) orogenical（P<sub>1</sub>-T<sub>1</sub>）;and c) dyke（P<sub>2</sub>-T<sub>1</sub>-K）.Different ore deposits occurrences are connected with these rock complexes of Chatkal-Kurama region.
文摘The emergence of the Qing—Zang plateau is among the most important geological events on the globe since the Cenozoic Era. Many geological issues can find answer from here. The major issues concerning plateau probably have three: (1) geodynamics, timing and speed of the plateau uplift;(2) The plateau uplift impact on surrounding environment;(3) mineral resources in the plateau. The authors want to focuses on first issue based on volcanisms occurred in interior and surrounding of the plateau, The new opinions are following:(1) Each volcanic eruptive episode corresponded to strong uplift stage;(2) The dynamic mechanism of the plateau uplift can not ignore another force from west beyond collision between Indian and Eurasia plates from South;(3) The surrounding volcanic chain is not only related to the collision from South, but also from west.
