2006 Vol. 39 No. 4
2006, 39(4): 1-9.
Abstract：
Geochemical analysis of the volcanic rocks of the Bikou group from the southern Tongqianban-Tuohe region reveals that they are of the alkaline basalts and subalkaline tholeiitic basalts,which have an affinity to the typical ocean island basalts (OIB) in the contents of Nb,Ta,Ce and the Ba/Ce,Ti/Y and Zr/Y ratios. In addition,the N-MORB-normalized spider diagram and the Chondrite-normalized REE pattern show that the two kinds of rocks were generated from the same parental magmatic source. The tectonic discrimination diagrams of the 2Nb-Zr/4-Y,TiO2-MnO-P2O5,Ti/Y-Ba/Zr and Ti/Y-Ba/Nb have fairly signified that the rocks occurred in an intra-oceanic tectonic setting,which would be a critical evidence to confirm an oceanic basin developed in the study region in the Neoproterozioc time.
Geochemical analysis of the volcanic rocks of the Bikou group from the southern Tongqianban-Tuohe region reveals that they are of the alkaline basalts and subalkaline tholeiitic basalts,which have an affinity to the typical ocean island basalts (OIB) in the contents of Nb,Ta,Ce and the Ba/Ce,Ti/Y and Zr/Y ratios. In addition,the N-MORB-normalized spider diagram and the Chondrite-normalized REE pattern show that the two kinds of rocks were generated from the same parental magmatic source. The tectonic discrimination diagrams of the 2Nb-Zr/4-Y,TiO2-MnO-P2O5,Ti/Y-Ba/Zr and Ti/Y-Ba/Nb have fairly signified that the rocks occurred in an intra-oceanic tectonic setting,which would be a critical evidence to confirm an oceanic basin developed in the study region in the Neoproterozioc time.
2006, 39(4): 10-15.
Abstract：
The Jurassic strata were discovered in the Luobubo area,Xinjiang. The strata are comprised of mudstones,siltstones,sandstones,conglomerates and interbedded coal beds. Abundant and well-preserved silicified wood (Coniferae sp.,Cupressinoxycnn sp.)was found in the Qiakemake formation mudstones and siltstones of upper Jurassic secession,and two coal beds (0.3m and 0.4m thick) occur in the Sukang (Qiakemake) formation. The Jurassic strata has been the first time found in the northestern Aman Depression of the Tarim basin. Therefore,this discovery is significancant for Jurassic stratigraphical study and oil and gas development in the Tarim basin.
The Jurassic strata were discovered in the Luobubo area,Xinjiang. The strata are comprised of mudstones,siltstones,sandstones,conglomerates and interbedded coal beds. Abundant and well-preserved silicified wood (Coniferae sp.,Cupressinoxycnn sp.)was found in the Qiakemake formation mudstones and siltstones of upper Jurassic secession,and two coal beds (0.3m and 0.4m thick) occur in the Sukang (Qiakemake) formation. The Jurassic strata has been the first time found in the northestern Aman Depression of the Tarim basin. Therefore,this discovery is significancant for Jurassic stratigraphical study and oil and gas development in the Tarim basin.
2006, 39(4): 16-23.
Abstract：
The stalagmite P1,P2 of Panlong cave and stalagmite X1 of Xiangshui cave in Guilin(which their ages are 30 ka BP,over 350 ka BP and 56ka BP,respectively),the stalagmite D3, D4 of Dongge cave and stalagmite Y1 of Yaman cave in Libo(which their ages are from 64 ka BP to 19ka BP,over 155 ka BP and from 53ka BP from 7.3 ka BP,respectively),the stalagmite Q14,Q16 of Qixing cave in Duyun(which their ages are from 64 ka BP to 19ka BP,over 155 ka BP and from 53ka BP from 7.3 ka BP, respectively ),Guizhou,and the stalagmiteLL1,LL5 of Linhua cave in longshan(which their ages are from 60 ka BP to 21a BP,and from 80 ka BP from 6 ka BP,respectively),Hunan,have been studied and integrated for many years. The characteristics of depositional cycles,micro-lamina and bedding plane structure in large stalagmites with height from 150cm to 400cm have obviously typicalness and representativeness.
The stalagmite P1,P2 of Panlong cave and stalagmite X1 of Xiangshui cave in Guilin(which their ages are 30 ka BP,over 350 ka BP and 56ka BP,respectively),the stalagmite D3, D4 of Dongge cave and stalagmite Y1 of Yaman cave in Libo(which their ages are from 64 ka BP to 19ka BP,over 155 ka BP and from 53ka BP from 7.3 ka BP,respectively),the stalagmite Q14,Q16 of Qixing cave in Duyun(which their ages are from 64 ka BP to 19ka BP,over 155 ka BP and from 53ka BP from 7.3 ka BP, respectively ),Guizhou,and the stalagmiteLL1,LL5 of Linhua cave in longshan(which their ages are from 60 ka BP to 21a BP,and from 80 ka BP from 6 ka BP,respectively),Hunan,have been studied and integrated for many years. The characteristics of depositional cycles,micro-lamina and bedding plane structure in large stalagmites with height from 150cm to 400cm have obviously typicalness and representativeness.
2006, 39(4): 24-32.
Abstract：
Copper deposits of the Fenghuoshan area geologically occur in the western portion of the Sanjiang nonferrous and noble metal mineralizatin belt,which is well known in China. The previous backward work hinders the study of the mineralization settings and genesis of the deposits. Recently,as geological survey and mineral resource exploration are carried out,some general geological information has become clear. As a result,sedimentary circumstances of the Fenghuoshan group,its sequences and the ore-bearing strata as well as the deformation sequences have been determined. Based on field work,we have analyzed the characteristics and genesis of the copper deposits. It is suggested that the Fenghuoshan copper deposits are hosted by sandstones,the ore bodies usually appear in grey and thick to intermediate thick,fine-grained quartz lithic sandstones intercalating with thin carbonaceous mudstones.
Copper deposits of the Fenghuoshan area geologically occur in the western portion of the Sanjiang nonferrous and noble metal mineralizatin belt,which is well known in China. The previous backward work hinders the study of the mineralization settings and genesis of the deposits. Recently,as geological survey and mineral resource exploration are carried out,some general geological information has become clear. As a result,sedimentary circumstances of the Fenghuoshan group,its sequences and the ore-bearing strata as well as the deformation sequences have been determined. Based on field work,we have analyzed the characteristics and genesis of the copper deposits. It is suggested that the Fenghuoshan copper deposits are hosted by sandstones,the ore bodies usually appear in grey and thick to intermediate thick,fine-grained quartz lithic sandstones intercalating with thin carbonaceous mudstones.
2006, 39(4): 33-39.
Abstract：
The gold and copper orebodies of the Ershiyizhan deposits are different in terms of their spatial distribution. The gold bodies,in a northwestern extension,are located in the southwestern contact of the intrusive,while the copper orebodies are centered inside the intrusive and stretch northeast. Based on the geological features of the Ershiyizhan gold copper deposits,this paper studies the controls factors and proposes a metallogenic model for the deposits:the gold and copper deposits belong to different products of different genesis type and metallogenic periods. The mineralization-related intrusive was emplaced in three times after magmatic differentiation of the crust-mantle mixed magmas.
The gold and copper orebodies of the Ershiyizhan deposits are different in terms of their spatial distribution. The gold bodies,in a northwestern extension,are located in the southwestern contact of the intrusive,while the copper orebodies are centered inside the intrusive and stretch northeast. Based on the geological features of the Ershiyizhan gold copper deposits,this paper studies the controls factors and proposes a metallogenic model for the deposits:the gold and copper deposits belong to different products of different genesis type and metallogenic periods. The mineralization-related intrusive was emplaced in three times after magmatic differentiation of the crust-mantle mixed magmas.
2006, 39(4): 40-56.
Abstract：
Nowthwest China has rich coal resources,which are accounted for 76.46 percent of the total forecast coal reserves in the nation. The major coal basins are the Ordos,the Junggar,the Tyrpan-Hami and the northern Tarim basins. Of the basins,the Ordos basin has a stable cratonic basement on which the Carboniferous-Permian north China type marine-continental facies and also Triassic-Jurassic intracontinent-lacustrine caol-bearing strata were deposited. The Junggar,Tyrpan-Hami and Northern Tarim basins belong to the Jurassic intracontinental lacustrine coal basins with the stable continental basement. The Ili,Youledusi,Yanqi and Kumishi basins are intermountane fault basins on the basement of the Hercynian fold zone. The basement of the Hexizoulang basin groups is the Caledonian fold zone. Alsly and Qaidam massifs covered by desert have palaeogeographic conditions for coal accumulation during the Paleozoic and Mesozoic. In fact,some small coal basin groups have been found on the southern margin of the two massifs.
Nowthwest China has rich coal resources,which are accounted for 76.46 percent of the total forecast coal reserves in the nation. The major coal basins are the Ordos,the Junggar,the Tyrpan-Hami and the northern Tarim basins. Of the basins,the Ordos basin has a stable cratonic basement on which the Carboniferous-Permian north China type marine-continental facies and also Triassic-Jurassic intracontinent-lacustrine caol-bearing strata were deposited. The Junggar,Tyrpan-Hami and Northern Tarim basins belong to the Jurassic intracontinental lacustrine coal basins with the stable continental basement. The Ili,Youledusi,Yanqi and Kumishi basins are intermountane fault basins on the basement of the Hercynian fold zone. The basement of the Hexizoulang basin groups is the Caledonian fold zone. Alsly and Qaidam massifs covered by desert have palaeogeographic conditions for coal accumulation during the Paleozoic and Mesozoic. In fact,some small coal basin groups have been found on the southern margin of the two massifs.
2006, 39(4): 57-64.
Abstract：
Northwest China is one of the most abundant areas in oil shale in the nation,where oil shale is widely distributed in a number of large sedimentary basins such as the Ordos,Zhungerer,Tarim,Qaidam and Ejina-Yingen,and also some medium-small size basins such as the continental facies intermontane basins in the Daqingshan and Yinshan areas as well as in the Qilian-Hexi Corridor (west to the Dunhuang basin,east to the Liupanshan basin-Bayanhot basin,south to the Qaidam basin,including many Meso-Cenozoic sedimentary basins with Paleozoic basement).By analysis of formation conditions and genetic type of different sedimentary basins in northwest China,The author proposed three genetic types of oil shale:deep lacustrine-moderate lacustrine facies,marine-continetal interactive facies and swamp facies. It is suggested that the deep lacustrine-moderate lacustrine facies of large inland basin is the most favorable exploration targetbecause of its steady sedimentary environment,abundant organic matterand other characteristics such as wide distribution,great thickness and steady oil content which made oil shale deposit much easier.
Northwest China is one of the most abundant areas in oil shale in the nation,where oil shale is widely distributed in a number of large sedimentary basins such as the Ordos,Zhungerer,Tarim,Qaidam and Ejina-Yingen,and also some medium-small size basins such as the continental facies intermontane basins in the Daqingshan and Yinshan areas as well as in the Qilian-Hexi Corridor (west to the Dunhuang basin,east to the Liupanshan basin-Bayanhot basin,south to the Qaidam basin,including many Meso-Cenozoic sedimentary basins with Paleozoic basement).By analysis of formation conditions and genetic type of different sedimentary basins in northwest China,The author proposed three genetic types of oil shale:deep lacustrine-moderate lacustrine facies,marine-continetal interactive facies and swamp facies. It is suggested that the deep lacustrine-moderate lacustrine facies of large inland basin is the most favorable exploration targetbecause of its steady sedimentary environment,abundant organic matterand other characteristics such as wide distribution,great thickness and steady oil content which made oil shale deposit much easier.
2006, 39(4): 65-73.
Abstract：
Neotectonic movement in the Jiyang depression mainly formed faults and anticlines,especially, the large revived faults and its fractures. These structures play a important role in the processes of oil and gas accumulation. Neotectonic movement induces and drives oil and gas out from hydrocarbon source rocks in form of faults system,which improves efficiency and power of expulsion and influents orientation of oil and gas migration and controls north-east extension of main pools;conducts and envelops oil and gas, small faults and microcracks conduct oil and gas,form pool of sandstone lens in sub-depression; Neotectonic movement controls hydrocarbon to cyclic accumulate;mufti-conductive systems linked large upper Tertiary drape anticlines and prolific source rocks and formed large and medium size fields like Gudao and Chengdong and so on. In this paper,above-described effects derived from Neotectonic movement in the processes of reservoir-forming is called oil pool-forming effect whose study can reevaluate petroleum resources of basin,and reveal mechanism,pattern and law of oil pool-forming.
Neotectonic movement in the Jiyang depression mainly formed faults and anticlines,especially, the large revived faults and its fractures. These structures play a important role in the processes of oil and gas accumulation. Neotectonic movement induces and drives oil and gas out from hydrocarbon source rocks in form of faults system,which improves efficiency and power of expulsion and influents orientation of oil and gas migration and controls north-east extension of main pools;conducts and envelops oil and gas, small faults and microcracks conduct oil and gas,form pool of sandstone lens in sub-depression; Neotectonic movement controls hydrocarbon to cyclic accumulate;mufti-conductive systems linked large upper Tertiary drape anticlines and prolific source rocks and formed large and medium size fields like Gudao and Chengdong and so on. In this paper,above-described effects derived from Neotectonic movement in the processes of reservoir-forming is called oil pool-forming effect whose study can reevaluate petroleum resources of basin,and reveal mechanism,pattern and law of oil pool-forming.
2006, 39(4): 74-83.
Abstract：
The Yanqi basin is located in the east of South Tianshan orogenic belt. As a small Jurassic petroleum basin,the Yanqi basin,which is similar to the surrounding basins such as the Tarim,and the Tupan basins,has its owns peculiar characteristics of petroleum geology. This study,based on the essential characteristics of generation,reservoir,cap rocks,and trap,focuses on the conditions of the petroleum formation of Bohu depression. Through organic matter types,abundance and degree of thermal evolution,it shows that pelites of the lower Jurassic Badaowan group are main hydrocarbon source rocks. The reservoir has low porosity and permeability and drilling data indicate there are two suites of reservoir-cover. Hydrocarbon generation history,authigenici llite chronological study and homogenization temperatures of fluid inclusions,show that there have two stages of petroleum generation and accumulation.
The Yanqi basin is located in the east of South Tianshan orogenic belt. As a small Jurassic petroleum basin,the Yanqi basin,which is similar to the surrounding basins such as the Tarim,and the Tupan basins,has its owns peculiar characteristics of petroleum geology. This study,based on the essential characteristics of generation,reservoir,cap rocks,and trap,focuses on the conditions of the petroleum formation of Bohu depression. Through organic matter types,abundance and degree of thermal evolution,it shows that pelites of the lower Jurassic Badaowan group are main hydrocarbon source rocks. The reservoir has low porosity and permeability and drilling data indicate there are two suites of reservoir-cover. Hydrocarbon generation history,authigenici llite chronological study and homogenization temperatures of fluid inclusions,show that there have two stages of petroleum generation and accumulation.
2006, 39(4): 84-88.
Abstract：
The study on the diagenesis course of Cretaceous and Jurassic reservoir in the Luliang oil field indicates that evolution of reservoir pores is closely related to compaction,solution and cementation. Compaction,quartz secondary enlargement and kaolinite an aphase-infilling are main diageneses to damage pores. The solution of felspar and carbonate minerals are the chief diageneses to form sencondary pores. Space-time configuration of various diageneses controll the development of pores. Development of reservoir pores in vertical zoning formed a secondary pores belt. So,it is significant to forecast spatial distribution of the reservoir physical properties.
The study on the diagenesis course of Cretaceous and Jurassic reservoir in the Luliang oil field indicates that evolution of reservoir pores is closely related to compaction,solution and cementation. Compaction,quartz secondary enlargement and kaolinite an aphase-infilling are main diageneses to damage pores. The solution of felspar and carbonate minerals are the chief diageneses to form sencondary pores. Space-time configuration of various diageneses controll the development of pores. Development of reservoir pores in vertical zoning formed a secondary pores belt. So,it is significant to forecast spatial distribution of the reservoir physical properties.
2006, 39(4): 89-96.
Abstract：
Study on sedimentary facies and microfacies of the known reservoir of the Chang 6 member of the Yanchang formation in the Xiasiwan Oilfield indicates that the dominant reservoirs are distributary channels and river mouth bar microfacies in the delta frontal surfaces of this region. Also,the accumulation of oil and gas is controlled by gentle structures. And find that source bed,reservoir and cap rocks are in a excellent combination,providing conditions for large-scale hydrocarbon accumulations. The exploration should be planned around the identified pool and then extended to both east and west in direction.
Study on sedimentary facies and microfacies of the known reservoir of the Chang 6 member of the Yanchang formation in the Xiasiwan Oilfield indicates that the dominant reservoirs are distributary channels and river mouth bar microfacies in the delta frontal surfaces of this region. Also,the accumulation of oil and gas is controlled by gentle structures. And find that source bed,reservoir and cap rocks are in a excellent combination,providing conditions for large-scale hydrocarbon accumulations. The exploration should be planned around the identified pool and then extended to both east and west in direction.
2006, 39(4): 97-104.
Abstract：
The oil-bearing Chang-3 member of the Yanchang Formation is one of the major oil producing formations in the Fuxian area,north Shaanxi. Chang-3 member belongs to an environment of delta frontal subfacies. The primary types of the reservoirs include distributary channel sandbodies,river mouth bar sandbodies. The secondary types are front-mat sand and distal bars. Statistics and analysis for 80 simples indicate that mineral maturity of Chang 3 reservoir is low,and textural maturity is medium-low. Reservoir diagensis types are relatively comlex and mainly consist of compaction, cementation and dissolution in the A period of the late stage. Diagenesis evolution can be divided into three stages:compaction and cementation to pore reduction,cementation,infilling and pore reduction and corrosion to pore enlargement. Petrophysical property analyses of 1747 simples from 18 wells show that the physical property of the Chang-3 member reservoir is of low porosity and very low permeable reservoir. Pore types are characterized by residual protozoal intergranular porosity and dissolution porosity. The reservoir is closely controlled by sedimentation and diagenesis. It is suggested that the Chang-3 reservoir can be divided into the high quality excellent,the intermediate quality and the low quality reservoirs. The physical property of the Chang 32 reservoir is bettern that Chang 31 and Chang 33.
The oil-bearing Chang-3 member of the Yanchang Formation is one of the major oil producing formations in the Fuxian area,north Shaanxi. Chang-3 member belongs to an environment of delta frontal subfacies. The primary types of the reservoirs include distributary channel sandbodies,river mouth bar sandbodies. The secondary types are front-mat sand and distal bars. Statistics and analysis for 80 simples indicate that mineral maturity of Chang 3 reservoir is low,and textural maturity is medium-low. Reservoir diagensis types are relatively comlex and mainly consist of compaction, cementation and dissolution in the A period of the late stage. Diagenesis evolution can be divided into three stages:compaction and cementation to pore reduction,cementation,infilling and pore reduction and corrosion to pore enlargement. Petrophysical property analyses of 1747 simples from 18 wells show that the physical property of the Chang-3 member reservoir is of low porosity and very low permeable reservoir. Pore types are characterized by residual protozoal intergranular porosity and dissolution porosity. The reservoir is closely controlled by sedimentation and diagenesis. It is suggested that the Chang-3 reservoir can be divided into the high quality excellent,the intermediate quality and the low quality reservoirs. The physical property of the Chang 32 reservoir is bettern that Chang 31 and Chang 33.
2006, 39(4): 105-109.
Abstract：
Due to the complex geo-environment and the increasingly unreasonable human activities, geological hazards have frequently occurred in the Baoji area. Thus,the area has become one of the areas with severe geological hazards in Shaanxi province. 784 sites of geological hazards have been found in the area,which cause governmental and public attention. The study analyzes the present situation,the distribution characteristics and the causes for the geological hazards in the area. Furthermore,the study points out some problems for the hazards prevention. Finally,some suggestions for the geological hazard prevention are given. All these would be meaningful for the prevention and cure of the geological hazards in the aera.
Due to the complex geo-environment and the increasingly unreasonable human activities, geological hazards have frequently occurred in the Baoji area. Thus,the area has become one of the areas with severe geological hazards in Shaanxi province. 784 sites of geological hazards have been found in the area,which cause governmental and public attention. The study analyzes the present situation,the distribution characteristics and the causes for the geological hazards in the area. Furthermore,the study points out some problems for the hazards prevention. Finally,some suggestions for the geological hazard prevention are given. All these would be meaningful for the prevention and cure of the geological hazards in the aera.
