On the basis of the characteristics of geology and geophysics in North China, three types of lithosphere, namely, the cratonic, the orogenic and the rift lithospheres can be classified. In terms of petrological method...On the basis of the characteristics of geology and geophysics in North China, three types of lithosphere, namely, the cratonic, the orogenic and the rift lithospheres can be classified. In terms of petrological method (based on the information from Precambrian rock assemblages, igneous activities, deep-seated enclaves, etc.) and the relationship between seismic velocity and rock compositions, the crust-mantle petrological and chemical structure models can be set up. Researching results indicate that the geology and geophysics of North China platform bears the similar characteristics in comparison with those of the global typical cratons. The Eerduosi(Ordos) block located in the west of the North China Platform is a remnant of cratonic lithosphere after the North China platform had undergone “activation” in Mesozoic and “reconstruction” in Cenozoic times. The continental crust consists mainly of TTG rock assemblage while the subcontinental lithosphere mantle mainly consists of strongly depleted harzburgite. The craton was finally formed in late Archaean and early Proterozoic, and has been kept in stability up to present; its crustal-mantle petrological structures of lithosphere can be set up as a reference for the study of North China craton and even Sino-Korean craton. In the Mesozoic period, the middle and east areas of North China platform were activated in the Yanshanian orogenic process, the continental crust was reformed by material and heat-transfer of convective mantle and the original crustal TTG component was reconstructed to be granitic crust, and the subcontinental lithosphere man- tle was replaced by the Yanshanian harzburgite-lherzolite. The Yanshan-Taihang Mountains were the remnants of orogenic lithosphere after the rifting in eastern North China in Cenozoic. The present thickness of continental crust and lithosphere in the Yanshan-Taihang Mountains is not equal to their thickness during the Yanshanian orogenic movement because they had undergone the crustal extensional thinning in Cenozoic展开更多
Determining the tectonic setting of unknown volcanic rocks continues to be one of the key challenges in geoscience.While discrimination diagrams have been successfully employed due to their ease of use,recently,valida...Determining the tectonic setting of unknown volcanic rocks continues to be one of the key challenges in geoscience.While discrimination diagrams have been successfully employed due to their ease of use,recently,validation with big data has raised questions about their performance.In this study,the discrimination boundaries of Th/Yb versus(vs.)Nb/Yb and TiO2/Yb vs.Nb/Yb diagrams,which are the most used types of discrimination diagrams,were redefined based on a large amount of compiled data and support vector machine,a machine learning method.The effectiveness of discrimination diagrams was verified,and the limitations and conditions when using them were clarified.The results show that when using the Th/Yb vs.Nb/Yb diagram,only basalts with Th/Yb ratios higher than the discrimination boundary can be identified as volcanic arcs in origin.In contrast,a significant overlap occurs across boundaries in other cases when using these diagrams,particularly for enriched samples with Nb/Yb ratios higher than five.Therefore,when using these diagrams to determine the tectonic setting of unknown samples,their limitations must be considered when interpreting their results.展开更多
Geotectonically, the Shuikou ultrabasic-basic rock mass is located on the western margin of the Yangtze Platform. As revealed by field geological surveys, the Shuikou rock mass intrudes into the quartz sandstones of t...Geotectonically, the Shuikou ultrabasic-basic rock mass is located on the western margin of the Yangtze Platform. As revealed by field geological surveys, the Shuikou rock mass intrudes into the quartz sandstones of the Sinian Chengjiang Formation (Zac). It is dominated by pyroxenites and can be roughly divided into four lithofacies zones, namely gabbros at the outermost periphery and fine-, medium-, and coarse-grained pyroxenites from margin to center. With the transition from pyroxenites to gabbros, the Shuikou rock mass features gradual enrichment in silica and alkali overall, an increase in ΣREE and (La/Yb)<sub>N</sub> ratio, and a decrease in δEu values and Eu/Sm ratio, indicating that the Shuikou rock mass was formed from the continuous differentiation and crystallization of consanguineous magma and that low-degree partial melting occurred meanwhile. According to the U-Pb baddeleyite geochronology, the crystallization age of the Shuikou rock mass is 210.7 ± 3 Ma (MSWD = 1.01). Based on this, as well as the analysis of geochemical characteristics, the Shuikou rock mass occurred in a continental intraplate tensional environment, this is closely related to the activities of the Emeishan mantle plume during the same period.展开更多
The southeast depression of Qinnan Sag is a potential oil-gas exploration region in the Bohai Sea area. With the analysis of large quantity of rock thin sections,scanning electron microscope and the physical property ...The southeast depression of Qinnan Sag is a potential oil-gas exploration region in the Bohai Sea area. With the analysis of large quantity of rock thin sections,scanning electron microscope and the physical property data of reservoir,the authors studied the petrological characteristics and the evolution of pore and fluid of sandstone in the deeper strata in 29-2 structure in Qinhuangdao area. The results show that the evolutionary tendency of Paleogene sandstone reservoir porous fluid in research area is changed from alkaline porous fluid to acidic porous fluid,and back to alkaline porous fluid. There are three stages of reservoir porous evolution in Qinhuangdao area,namely sharp decrease in porosity due to mechanical compaction,increase in porosity because of corrosion and dissolution,and remarkable reduction owing to carbonate cementation.展开更多
Upper Carboniferous-Lower Permian volcanic event deposits from two cross sections in Nanpiao, Liaoning Province, and the Daqing Mountains, Inner Mongolia, were examined by systematic rock and mineral identification, d...Upper Carboniferous-Lower Permian volcanic event deposits from two cross sections in Nanpiao, Liaoning Province, and the Daqing Mountains, Inner Mongolia, were examined by systematic rock and mineral identification, differential thermal analysis, X-ray diffraction, scanning electron microscopy and trace element and rare earth element quantitative analysis. According to the results, twelve sequences of volcanic event deposits have been distinguished from bottom to top, including 34–39 volcanic event layers. As these layers each have their own distinctive petrological, mineralogical and geochemical characteristics and were derived from the same source, they provide new evidence for further ascertaining the distribution characteristics of volcanic event deposits on the northern margin of the North China plate and carrying out the stratigraphic correlation using volcanic event layers as marker beds.展开更多
Petrological and mineralogical characteristics of gabbro xenoliths in Mesozoic basalts in Ningyuan-Daoxian region, Huan province show that they belong to different rock series. The basalt is similar to alkline basalt ...Petrological and mineralogical characteristics of gabbro xenoliths in Mesozoic basalts in Ningyuan-Daoxian region, Huan province show that they belong to different rock series. The basalt is similar to alkline basalt of an intracontinental rift ; while the gabbro xenolith shows that it is the differentiated outcrop of tholeiitic lava, similar to that of layer-shaped basic pluton. The gabbro xenolith represents an early intrusion of basic melt and the melting event is probably the earlier menifestation of lithosphere mibilization in Mesozoic in the South China.展开更多
With the in-depth development of the Sargiz oilfield in Kazakhstan, oil layer protection plays an extremely important role in the development process. The petrological characteristics and pore types of the reservoir w...With the in-depth development of the Sargiz oilfield in Kazakhstan, oil layer protection plays an extremely important role in the development process. The petrological characteristics and pore types of the reservoir were analyzed by X-ray diffraction and electron microscopy. The average face ratio of the reservoir was 19.30%. The main pore type was intergranular pore and the face rate was 17.52%. The total amount of clay minerals in the reservoir core is 7% - 10%, and the clay minerals are mainly illite, Yimeng, kaolinite and chlorite;the shale content of the main oil-bearing layer is about 3% - 10%. Refer to relevant industry standards for speed, water, stress, acid, and alkali sensitivity experiments to study the potential damage mechanism of the reservoir. According to the above experiments, the oilfield reservoirs have no speed-sensitive damage and are weakly water-sensitive reservoirs;the reservoirs are highly stress-sensitive and easy to produce sand when the stress changes;they have moderately weak acid sensitivity and weak-medium weak alkaline.展开更多
The Western Yunnan is just situated in juncture area of the Yangtze,Indosinia and Shan-Thai Microcontinents,with the geosuture zones among them marked by ophiolite suites and blue schists.Agreat number of petrological...The Western Yunnan is just situated in juncture area of the Yangtze,Indosinia and Shan-Thai Microcontinents,with the geosuture zones among them marked by ophiolite suites and blue schists.Agreat number of petrological data support systematic evidences for Paleo-Tethys occurring in the area,andaccording to them,the tectonic evolution is reconstructed.Paleo-Tethys might be a poly-island ocean duringthe Late Paleozoic,and relic oceanic basins developed in Triassic1 Neo-Tethys immigrated westwards intoBurma.The area is an orogenic belt experiencing complicated subduction and violent continent-continent col-lision,and reformed by the younger structures,specially the Himalayan movement.展开更多
The India-Asia collision and uplift of the Tibetan plateau are the most important geological events in Earth＇s history; it profoundly affects our understanding of global climate change during the Cenozoic. Despite a ...The India-Asia collision and uplift of the Tibetan plateau are the most important geological events in Earth＇s history; it profoundly affects our understanding of global climate change during the Cenozoic. Despite a research history over half a century, the uplifting history remains hotly controversial. The early uplifting model suggested that the Lhasa terrane attained an elevation of 3-4 km at -99 Ma due to the Lhasa-Qiangtang collision. However, the evidences are mainly from deformation of the Lhasa terrane and inconsistency with the palaeontological data.展开更多
In recent years,with the success of exploration and development of conglomerate reservoirs in Mahu Depression,Junggar Basin,China,it is urgent to study the mechanical properties and its influencing factors of conglome...In recent years,with the success of exploration and development of conglomerate reservoirs in Mahu Depression,Junggar Basin,China,it is urgent to study the mechanical properties and its influencing factors of conglomerate which is considered as a new oil and gas reservoir.Based on the investigations of petrologic characteristics,heterogeneity and mechanical properties of conglomerate in Baikouquan formation,the content and geometric characteristics of gravel in conglomerate,the main factors in heterogeneity and the mechanical behavior in the triaxial compression experiment of conglomerate are analyzed in this paper.The results show that the size and content of gravel in conglomerate varies greatly,and conglomerate has strong heterogeneity under the influence of gravel content and size.An analysis of mechanical properties of conglomerate shows that conglomerate is characterized by plasticity.Besides,the sphericity is negatively correlated to the gravel content,while the heterogeneity increases with the increase of conglomerate plasticity.Due to the existence of heterogeneous gravel,local stress may concentrate in conglomerate when the stress is loaded.Consequently,a large number of micro-cracks appear at the edge of gravel,demonstrating the strong plasticity of conglomerate.This paper is of referential significance to the study of rock mechanical properties and the evaluation of engineering properties in conglomerate development.展开更多
A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in the...A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in thecourse of the Caledonian-Indosinian ductilc and brittle-ductile reworking. The study on their petrography. va-riations in composition and conditions of formation is conducive to revealing the metamorphism-deformationhistory of the core of the Qinling orogenic belt and further to understanding the dynamic mechanism of its evo-lution.展开更多
基金supported by the Special Program of the Ministry of Land and Resources of China(Grant Nos.200010103 and 20001010202)the Researching Project of Deep-Level Substance’s Model of China Lithosphere,the Key Laboratory of Lithosphere Tectonics and Explorat ion,China Univers ity of Geosciences,Ministry of Education of China(Grant Nos.2003009 and 2003010)+1 种基金the Project of Key Problem on the Granite Geology in China,China Geological Survey(Grant No.200113900018)the National Natural Science Foundation of China(Grant No.402344048).
文摘On the basis of the characteristics of geology and geophysics in North China, three types of lithosphere, namely, the cratonic, the orogenic and the rift lithospheres can be classified. In terms of petrological method (based on the information from Precambrian rock assemblages, igneous activities, deep-seated enclaves, etc.) and the relationship between seismic velocity and rock compositions, the crust-mantle petrological and chemical structure models can be set up. Researching results indicate that the geology and geophysics of North China platform bears the similar characteristics in comparison with those of the global typical cratons. The Eerduosi(Ordos) block located in the west of the North China Platform is a remnant of cratonic lithosphere after the North China platform had undergone “activation” in Mesozoic and “reconstruction” in Cenozoic times. The continental crust consists mainly of TTG rock assemblage while the subcontinental lithosphere mantle mainly consists of strongly depleted harzburgite. The craton was finally formed in late Archaean and early Proterozoic, and has been kept in stability up to present; its crustal-mantle petrological structures of lithosphere can be set up as a reference for the study of North China craton and even Sino-Korean craton. In the Mesozoic period, the middle and east areas of North China platform were activated in the Yanshanian orogenic process, the continental crust was reformed by material and heat-transfer of convective mantle and the original crustal TTG component was reconstructed to be granitic crust, and the subcontinental lithosphere man- tle was replaced by the Yanshanian harzburgite-lherzolite. The Yanshan-Taihang Mountains were the remnants of orogenic lithosphere after the rifting in eastern North China in Cenozoic. The present thickness of continental crust and lithosphere in the Yanshan-Taihang Mountains is not equal to their thickness during the Yanshanian orogenic movement because they had undergone the crustal extensional thinning in Cenozoic
文摘Determining the tectonic setting of unknown volcanic rocks continues to be one of the key challenges in geoscience.While discrimination diagrams have been successfully employed due to their ease of use,recently,validation with big data has raised questions about their performance.In this study,the discrimination boundaries of Th/Yb versus(vs.)Nb/Yb and TiO2/Yb vs.Nb/Yb diagrams,which are the most used types of discrimination diagrams,were redefined based on a large amount of compiled data and support vector machine,a machine learning method.The effectiveness of discrimination diagrams was verified,and the limitations and conditions when using them were clarified.The results show that when using the Th/Yb vs.Nb/Yb diagram,only basalts with Th/Yb ratios higher than the discrimination boundary can be identified as volcanic arcs in origin.In contrast,a significant overlap occurs across boundaries in other cases when using these diagrams,particularly for enriched samples with Nb/Yb ratios higher than five.Therefore,when using these diagrams to determine the tectonic setting of unknown samples,their limitations must be considered when interpreting their results.
文摘Geotectonically, the Shuikou ultrabasic-basic rock mass is located on the western margin of the Yangtze Platform. As revealed by field geological surveys, the Shuikou rock mass intrudes into the quartz sandstones of the Sinian Chengjiang Formation (Zac). It is dominated by pyroxenites and can be roughly divided into four lithofacies zones, namely gabbros at the outermost periphery and fine-, medium-, and coarse-grained pyroxenites from margin to center. With the transition from pyroxenites to gabbros, the Shuikou rock mass features gradual enrichment in silica and alkali overall, an increase in ΣREE and (La/Yb)<sub>N</sub> ratio, and a decrease in δEu values and Eu/Sm ratio, indicating that the Shuikou rock mass was formed from the continuous differentiation and crystallization of consanguineous magma and that low-degree partial melting occurred meanwhile. According to the U-Pb baddeleyite geochronology, the crystallization age of the Shuikou rock mass is 210.7 ± 3 Ma (MSWD = 1.01). Based on this, as well as the analysis of geochemical characteristics, the Shuikou rock mass occurred in a continental intraplate tensional environment, this is closely related to the activities of the Emeishan mantle plume during the same period.
基金Supported by Project of Tianjin Branch of CNOOC Ltd.(CCL2012TJXSBS0282)Project of CNOOC Ltd.,Research Center of Beijing(CCL2015RCPS0150RCN)Project of Institute of Mineral Resources,Chinese Academy of Geological Sciences,China Geological Survey(DD20160344)
文摘The southeast depression of Qinnan Sag is a potential oil-gas exploration region in the Bohai Sea area. With the analysis of large quantity of rock thin sections,scanning electron microscope and the physical property data of reservoir,the authors studied the petrological characteristics and the evolution of pore and fluid of sandstone in the deeper strata in 29-2 structure in Qinhuangdao area. The results show that the evolutionary tendency of Paleogene sandstone reservoir porous fluid in research area is changed from alkaline porous fluid to acidic porous fluid,and back to alkaline porous fluid. There are three stages of reservoir porous evolution in Qinhuangdao area,namely sharp decrease in porosity due to mechanical compaction,increase in porosity because of corrosion and dissolution,and remarkable reduction owing to carbonate cementation.
基金This research was supported by National Natural Science Foundation of China grant 49762094.
文摘Upper Carboniferous-Lower Permian volcanic event deposits from two cross sections in Nanpiao, Liaoning Province, and the Daqing Mountains, Inner Mongolia, were examined by systematic rock and mineral identification, differential thermal analysis, X-ray diffraction, scanning electron microscopy and trace element and rare earth element quantitative analysis. According to the results, twelve sequences of volcanic event deposits have been distinguished from bottom to top, including 34–39 volcanic event layers. As these layers each have their own distinctive petrological, mineralogical and geochemical characteristics and were derived from the same source, they provide new evidence for further ascertaining the distribution characteristics of volcanic event deposits on the northern margin of the North China plate and carrying out the stratigraphic correlation using volcanic event layers as marker beds.
文摘Petrological and mineralogical characteristics of gabbro xenoliths in Mesozoic basalts in Ningyuan-Daoxian region, Huan province show that they belong to different rock series. The basalt is similar to alkline basalt of an intracontinental rift ; while the gabbro xenolith shows that it is the differentiated outcrop of tholeiitic lava, similar to that of layer-shaped basic pluton. The gabbro xenolith represents an early intrusion of basic melt and the melting event is probably the earlier menifestation of lithosphere mibilization in Mesozoic in the South China.
文摘With the in-depth development of the Sargiz oilfield in Kazakhstan, oil layer protection plays an extremely important role in the development process. The petrological characteristics and pore types of the reservoir were analyzed by X-ray diffraction and electron microscopy. The average face ratio of the reservoir was 19.30%. The main pore type was intergranular pore and the face rate was 17.52%. The total amount of clay minerals in the reservoir core is 7% - 10%, and the clay minerals are mainly illite, Yimeng, kaolinite and chlorite;the shale content of the main oil-bearing layer is about 3% - 10%. Refer to relevant industry standards for speed, water, stress, acid, and alkali sensitivity experiments to study the potential damage mechanism of the reservoir. According to the above experiments, the oilfield reservoirs have no speed-sensitive damage and are weakly water-sensitive reservoirs;the reservoirs are highly stress-sensitive and easy to produce sand when the stress changes;they have moderately weak acid sensitivity and weak-medium weak alkaline.
基金the National Natural Science Foundation of China.
文摘The Western Yunnan is just situated in juncture area of the Yangtze,Indosinia and Shan-Thai Microcontinents,with the geosuture zones among them marked by ophiolite suites and blue schists.Agreat number of petrological data support systematic evidences for Paleo-Tethys occurring in the area,andaccording to them,the tectonic evolution is reconstructed.Paleo-Tethys might be a poly-island ocean duringthe Late Paleozoic,and relic oceanic basins developed in Triassic1 Neo-Tethys immigrated westwards intoBurma.The area is an orogenic belt experiencing complicated subduction and violent continent-continent col-lision,and reformed by the younger structures,specially the Himalayan movement.
基金financially supported by the National Natural Science Foundation of China(41572188)the China Geological Survey(DD20160159-06)
文摘The India-Asia collision and uplift of the Tibetan plateau are the most important geological events in Earth＇s history; it profoundly affects our understanding of global climate change during the Cenozoic. Despite a research history over half a century, the uplifting history remains hotly controversial. The early uplifting model suggested that the Lhasa terrane attained an elevation of 3-4 km at -99 Ma due to the Lhasa-Qiangtang collision. However, the evidences are mainly from deformation of the Lhasa terrane and inconsistency with the palaeontological data.
基金sponsored by the Development of conglomerate reservoir laboratory in Xinjiang(2019D04008)the National Natural Science Foundation of China(51604287)the Research Foundation of China University of Petroleum-Beijing at Karamay(RCYJ2016B-01-001)。
文摘In recent years,with the success of exploration and development of conglomerate reservoirs in Mahu Depression,Junggar Basin,China,it is urgent to study the mechanical properties and its influencing factors of conglomerate which is considered as a new oil and gas reservoir.Based on the investigations of petrologic characteristics,heterogeneity and mechanical properties of conglomerate in Baikouquan formation,the content and geometric characteristics of gravel in conglomerate,the main factors in heterogeneity and the mechanical behavior in the triaxial compression experiment of conglomerate are analyzed in this paper.The results show that the size and content of gravel in conglomerate varies greatly,and conglomerate has strong heterogeneity under the influence of gravel content and size.An analysis of mechanical properties of conglomerate shows that conglomerate is characterized by plasticity.Besides,the sphericity is negatively correlated to the gravel content,while the heterogeneity increases with the increase of conglomerate plasticity.Due to the existence of heterogeneous gravel,local stress may concentrate in conglomerate when the stress is loaded.Consequently,a large number of micro-cracks appear at the edge of gravel,demonstrating the strong plasticity of conglomerate.This paper is of referential significance to the study of rock mechanical properties and the evaluation of engineering properties in conglomerate development.
文摘A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in thecourse of the Caledonian-Indosinian ductilc and brittle-ductile reworking. The study on their petrography. va-riations in composition and conditions of formation is conducive to revealing the metamorphism-deformationhistory of the core of the Qinling orogenic belt and further to understanding the dynamic mechanism of its evo-lution.
