Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo-China plates....Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo-China plates. GSZ are closey related to gravity Moho gradient zones and lithospheric thickness. The GSZ between the Yangtze and Cathaysian plates is consistent with the Shizong-Mile tectonic belt, where island are basalts are well developed. The Yangtze-Indo-China GSZ is parallel to the Jingdong-Mojiang volcanic belt in rift-island are environments. The evidence of geology, geophysics and geochemistry all indicates that Cathaysia was subducted towards the Yangtze plate and that the Yangtze plate was underthrust beneath the Indo-China, which took place from the Early Carboniferous to the Early Triassic.展开更多
Lead isotopic geochemical steep-dipping zone usually exists on inhomogeneous boundaries of earth blocks. Its crossing with the geophysical gradient zone often convergently occurs at giant deposits. Deep structures or ...Lead isotopic geochemical steep-dipping zone usually exists on inhomogeneous boundaries of earth blocks. Its crossing with the geophysical gradient zone often convergently occurs at giant deposits. Deep structures or concealed structural planes obviously have the coupling relationship with the convergent area of mineral deposits. The geochemical steep-dipping zone is usually distributed along the boundary of ancient continental blocks. Its crossing effect with geophysical gradient zone is usually presented as depression or swell of Moho discontinuity on the crossing direction with the ancient continental margin, which would lead to form deep fractures of earth crust at block margins or lead to adjustment of earth crust texture. The deep hydrothermal liquid would rise up along the structural planes to form the convergent areas of mineral deposits. For example, Luonan- Luanchuan area in east Qinling is a typical crossed area of the geochemical steepdipping zone and geophysical gradient zone. The mineral deposit belt extends along EW direction. It was controlled by the geochemical steepdipping zone equidistantly distributed along NE direction like a string of beads controlled by a gravity gradient zone in NE direction and a mantle depression slope. Along a plunging mantle syncline on EW plunging direction, from the east to the west, checkform was distributed which controls synergic crustmantle granoporphyry rocks. Therefore, a convergent mineralization area of Mo, W, Zn and Au giant deposits occurred.展开更多
Based on the Pb isotopic mapping of the continent of China and the geochemical data of Proterozoic basements, the steep zones of geochemical blocks of Cathaysia, Yangtze, North China, Central Mongolia, China\|Korea an...Based on the Pb isotopic mapping of the continent of China and the geochemical data of Proterozoic basements, the steep zones of geochemical blocks of Cathaysia, Yangtze, North China, Central Mongolia, China\|Korea and Jiamusi are established. There are tight relationships between geochemical steep zones and setting of the superlarge deposits along with main mineralization zones. There are Proterozoic basements belonging to different blocks on both sides of geochemical steep zones in which volcanism and SEDEX were comprehensively developed and associated with reconstruction ore emplacement of dynamic metamorphism and magmatism from Jinning period to Mesozoic\|Cenozoic.展开更多
THE parallel strike of geochemical steep zones and geophysical gradient zones represent geochemicalboundaries with tectonic hiding and almost no magmatism, but there existed great variation of lithosphereor crustal th...THE parallel strike of geochemical steep zones and geophysical gradient zones represent geochemicalboundaries with tectonic hiding and almost no magmatism, but there existed great variation of lithosphereor crustal thickness. Tectonically, these areas were located in the foreland basins of craton margin. Thesegeochemical boundaries were usually associated with the low-temperature mineralization and petroleumgeneration. The Nd, Sr and Pb isotopic evidence indicated that there still existed strong crustal-mantle interaction through fluid activation along deep-seated faults at the craton margin. Fig. 1 is the <sup>207</sup>Pb/<sup>204</sup> Pb-<sup>208</sup>Pb/<sup>204</sup> Pb diagram, which shows the evident crust-mantle mixing for crude oil, chloroform bitumen-A,展开更多
THE wildly horizontal and vertical chemical heterogeneties, which result from the inchoate core-mantledifferentiation of the globe and the spatio-temporal difference of various regions in the globe, bring on themantle...THE wildly horizontal and vertical chemical heterogeneties, which result from the inchoate core-mantledifferentiation of the globe and the spatio-temporal difference of various regions in the globe, bring on themantle and crust from different landmass and oceans with markedly elemental and isotopic signatures.Wherefore these signatures could be used to differentiate the attribute from various landmass or oceans andrecover the scent of kinematics and chemical geodynamics process. It is a quantificational method compared with the division by geotectonics facies and paleontologic fauna. Based on the geochemistry mapping of elements and multi-isotopic systematics of rocks derived frommantle and crust and combined with the studies on geophysical tomographic image, four type geochemicalprovinces can be distinguished. They are: (i) the Pacific (such as N-Pacific, N-Atlantic, the展开更多
基金This study was supported by the key project of Chinese Academy of Sciences KZ951-B1-413Project No.973 of the National Commission of Science and Technology(G1999043213).
文摘Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo-China plates. GSZ are closey related to gravity Moho gradient zones and lithospheric thickness. The GSZ between the Yangtze and Cathaysian plates is consistent with the Shizong-Mile tectonic belt, where island are basalts are well developed. The Yangtze-Indo-China GSZ is parallel to the Jingdong-Mojiang volcanic belt in rift-island are environments. The evidence of geology, geophysics and geochemistry all indicates that Cathaysia was subducted towards the Yangtze plate and that the Yangtze plate was underthrust beneath the Indo-China, which took place from the Early Carboniferous to the Early Triassic.
基金Fund of the National Climbing Project!( 95-pre-2 5 -03 ) the Ministry of Geology and Mineral ResourcesStudying Projec
文摘Lead isotopic geochemical steep-dipping zone usually exists on inhomogeneous boundaries of earth blocks. Its crossing with the geophysical gradient zone often convergently occurs at giant deposits. Deep structures or concealed structural planes obviously have the coupling relationship with the convergent area of mineral deposits. The geochemical steep-dipping zone is usually distributed along the boundary of ancient continental blocks. Its crossing effect with geophysical gradient zone is usually presented as depression or swell of Moho discontinuity on the crossing direction with the ancient continental margin, which would lead to form deep fractures of earth crust at block margins or lead to adjustment of earth crust texture. The deep hydrothermal liquid would rise up along the structural planes to form the convergent areas of mineral deposits. For example, Luonan- Luanchuan area in east Qinling is a typical crossed area of the geochemical steepdipping zone and geophysical gradient zone. The mineral deposit belt extends along EW direction. It was controlled by the geochemical steepdipping zone equidistantly distributed along NE direction like a string of beads controlled by a gravity gradient zone in NE direction and a mantle depression slope. Along a plunging mantle syncline on EW plunging direction, from the east to the west, checkform was distributed which controls synergic crustmantle granoporphyry rocks. Therefore, a convergent mineralization area of Mo, W, Zn and Au giant deposits occurred.
文摘Based on the Pb isotopic mapping of the continent of China and the geochemical data of Proterozoic basements, the steep zones of geochemical blocks of Cathaysia, Yangtze, North China, Central Mongolia, China\|Korea and Jiamusi are established. There are tight relationships between geochemical steep zones and setting of the superlarge deposits along with main mineralization zones. There are Proterozoic basements belonging to different blocks on both sides of geochemical steep zones in which volcanism and SEDEX were comprehensively developed and associated with reconstruction ore emplacement of dynamic metamorphism and magmatism from Jinning period to Mesozoic\|Cenozoic.
文摘THE parallel strike of geochemical steep zones and geophysical gradient zones represent geochemicalboundaries with tectonic hiding and almost no magmatism, but there existed great variation of lithosphereor crustal thickness. Tectonically, these areas were located in the foreland basins of craton margin. Thesegeochemical boundaries were usually associated with the low-temperature mineralization and petroleumgeneration. The Nd, Sr and Pb isotopic evidence indicated that there still existed strong crustal-mantle interaction through fluid activation along deep-seated faults at the craton margin. Fig. 1 is the <sup>207</sup>Pb/<sup>204</sup> Pb-<sup>208</sup>Pb/<sup>204</sup> Pb diagram, which shows the evident crust-mantle mixing for crude oil, chloroform bitumen-A,
文摘THE wildly horizontal and vertical chemical heterogeneties, which result from the inchoate core-mantledifferentiation of the globe and the spatio-temporal difference of various regions in the globe, bring on themantle and crust from different landmass and oceans with markedly elemental and isotopic signatures.Wherefore these signatures could be used to differentiate the attribute from various landmass or oceans andrecover the scent of kinematics and chemical geodynamics process. It is a quantificational method compared with the division by geotectonics facies and paleontologic fauna. Based on the geochemistry mapping of elements and multi-isotopic systematics of rocks derived frommantle and crust and combined with the studies on geophysical tomographic image, four type geochemicalprovinces can be distinguished. They are: (i) the Pacific (such as N-Pacific, N-Atlantic, the
