The Qujiashan manganese deposit is located in the Longmen-Daba fold belt along the northern margin of the Yangtze Block. The layered ore bodies are distributed within the purple-red calcareous shale. Qujiashan is a hi...The Qujiashan manganese deposit is located in the Longmen-Daba fold belt along the northern margin of the Yangtze Block. The layered ore bodies are distributed within the purple-red calcareous shale. Qujiashan is a high-grade w(MnO)=8.92% to 18.76%) manganese deposit with low-phosphorus w(P2O5)=0.08% to 0.16%) content. It also has a low total REEs contents(with an average of 101.3×10-6), and has inconspicuous Ce(0.81 to 1.29) and Eu(1.00 to 1.25) anomalies. lg(Ce/Ce*) values are from-0.02 to 0.11. The ores have high SiO2/Al2O3 and Al/(Al + Fe + Mn) ratios. In figures of Fe–Mn–[(Ni+Cu+Co)×10] and lgU–lgTh, all samples show that hydrothermal exhalative fluids played an important role during mineralisation. The δ13CPDB and δ18OSMOW values of eight ore samples are from-20.7‰ to-8.2‰(with an average of-12.4‰) and from 14.3‰ to 18.7‰(with an average of 17.0‰), respectively. These carbon and oxygen isotopic features indicate that hydrothermal fluids derived from deep earth are participation in the metallogenic process, which is also supported by high paleo-seawater temperatures varying from 47.08 to 73.98 °C. Therefore, the geological and geochemical evidences show that the Qujiashan deposit formed from submarine exhalative hydrothermal sedimentation.展开更多
Considering the serious coal and rock dynamic disasters around the main slip plane called F16 in the coal mining area) of Henan Yima(China) thrust nappe structure,the mechanical genesis of the Yima thrust nappe struct...Considering the serious coal and rock dynamic disasters around the main slip plane called F16 in the coal mining area) of Henan Yima(China) thrust nappe structure,the mechanical genesis of the Yima thrust nappe structure was studied comprehensively using geomechanics,fault mechanics,elastic mechanics,and Coulomb's law of friction.First,using the centrifugal inertia force of Earth's rotation as a source,a mechanical model of N-S compression superimposed with W-E reverse torsion was established to explain the formation of the early Yima coal basin and Jurassic Yima Group coal measures.Second,an equation for the ultimate stress in the forming stage of F16 was derived using the plastic slip-line field theory and the parabolic Mohr failure criterion.Moreover,the distribution of ultimate stress and the geometric characteristics of the fault profile were obtained using the field model parameters.Finally,the stress field of F16 and the mechanical genesis of the large-scale reverse thrust sheet were discussed based on elastic mechanics theory and Coulomb's law of friction.The results show that the tectonic framework of the early Yima coal basin and the formation pattern of Jurassic Yima Group coal measures given by the model are consistent with the in-situ explorations.The geometric characteristics of the fault profile obtained by numerical calculation can better reflect the shape of F16 in its forming stage,and the mechanical genesis of the large-scale reverse thrust sheet also concurred with the field situations.Thus,this work can provide a foundation for further studies on the genesis of the thrust nappe structure,the mechanism of rock bursts induced by F16,and the characteristics of the residual stress field in the Yima mining area.展开更多
The Kohistan Terrane in N. Pakistan straddles the suture zone between the collided Indian and Eurasian plates in the NW Himalayas of N. Pakistan. Initiated as an intra\|oceanic island\|arc crust in Neotethys, the terr...The Kohistan Terrane in N. Pakistan straddles the suture zone between the collided Indian and Eurasian plates in the NW Himalayas of N. Pakistan. Initiated as an intra\|oceanic island\|arc crust in Neotethys, the terrane accreted with the southern margin of the Karakoram Plate in the Late Cretaceous (about 90Ma). Continued subduction at its southern margin resulted in Andean\|type magmatism and tectonics, until collision with the Indian Plat in the Early Eocene.Whereas much of the central and eastern Kohistan expose Cretaceous volcanic and sedimentary rocks of intra\|oceanic island arc setting, the western Kohistan in Swat, Dir, Chitral and upper Ghizer valleys preserves remnants of the Late Paleocene—Early Eocene volcanism and sedimentation of Andean\|type setting. These volcano\|sedimentary lithologies in western Kohistan are geographically divisible into two, separated by the Lowari Pluton; (1) Dir\|Swat Belt, (2) Drosh\|Shamran Belt. Late Paleocene\|Early Eocene siliceous volcanics termed Utror Volcanics and Shamran Volcanics are common in the two belts and so are the plutons intrusive into these volcanics (Late Stage\|II of the Kohistan Batholith). The difference is in the sedimentary successions presented in the two belts. Whereas in the Dir\|Swat belt, the sedimentary succession comprises Baraul Banda Slate Formation, deposited in deep\|water fore\|arc setting and contemporaneous in age with that of the nearby Utror Volcanic Formation (about 55～60Ma), the sediments in the Drosh\|Shamran belt are distinctly red beds of fluvial origin (the Purit Formation) those overlie unconformably on top of the Shamran Volcanics and their equivalents.展开更多
The Yunnan Himalayan alkaline rich porphyry occurs as a compound rockbelt and consists of calca alkalic, alkaline and peralkaline intrusions. Its origin is in debate. The paper deals with its origin by studying rock′...The Yunnan Himalayan alkaline rich porphyry occurs as a compound rockbelt and consists of calca alkalic, alkaline and peralkaline intrusions. Its origin is in debate. The paper deals with its origin by studying rock′s REE and Sr isotope. Although the rocks are different in their REE contents varying from 77.53 μg/g to 1 798.3 μg/g, they have very similar features in REE parameters. On the triangalar diagram of REEs, the sample dots are concentrated on the end area of light REEs, representing a product of low degree melting of upper mantle or lower crust materials. The initial 87 Sr/ 86 Sr values of rocks vary between 0.706 4 and 0.709 8, showing a feature of mantle crust mixed source. Moreover, REEs show a logarithmic linear positive correlation between them. This type of correlation strongly supports the fractional partial melting model. The result of geochemistry inversion shows that the source rock of alkaline rich porphyry is plagioclase bearing harzburgite and of mantle crust mixed type. At the early state of melting, some crust components of the source rock were partially melted into intermediate acidic magma; with the crust components consumed, the magma evolved to basic.展开更多
The Lala Cu deposit in Sichuan Province is one of the most important large deposits in SW China,both in terms of Cu and associated Au-Mo-Co-REE-Fe. Systematic ore petrology study shows that ore minerals are mainly com...The Lala Cu deposit in Sichuan Province is one of the most important large deposits in SW China,both in terms of Cu and associated Au-Mo-Co-REE-Fe. Systematic ore petrology study shows that ore minerals are mainly composed of hydrothermal magnetite,chalcopyrite and molybdenite.The wall-rock alterations include biotitization,silicification, carbonatation,albitization,potash feldspathization, apatitation,actinolitation and fluoritation,et al. The Pyrite and magnetite have euhedral-subhedral crystalline grained texture and the chalcopyrite展开更多
There are many skarn deposits that occur in volcanic rocks as stratiform and lentoid bodies,for example the Lower Yangtze River Valley,Western Tianshan Mountains and Lhasa Terrane in China,the Nuuk in West Greeland an...There are many skarn deposits that occur in volcanic rocks as stratiform and lentoid bodies,for example the Lower Yangtze River Valley,Western Tianshan Mountains and Lhasa Terrane in China,the Nuuk in West Greeland and the Austroalpine Alps(e.g.Xv et al.,1984;Appel,1994;Raith and Stein,2000;Wang et al.,2001;Gu et al.,2007;Hou et al.,2011;Zhou et al.,2011;Jiang et al.,2012;Xu et al.,2010;Wang et al.,2012;Yu et al.,2011).展开更多
基金Project(41663006)supported by the National Natural Science Foundation of ChinaProject(1212011220725)supported by the Geological Survey Project of the China Geological Survey
文摘The Qujiashan manganese deposit is located in the Longmen-Daba fold belt along the northern margin of the Yangtze Block. The layered ore bodies are distributed within the purple-red calcareous shale. Qujiashan is a high-grade w(MnO)=8.92% to 18.76%) manganese deposit with low-phosphorus w(P2O5)=0.08% to 0.16%) content. It also has a low total REEs contents(with an average of 101.3×10-6), and has inconspicuous Ce(0.81 to 1.29) and Eu(1.00 to 1.25) anomalies. lg(Ce/Ce*) values are from-0.02 to 0.11. The ores have high SiO2/Al2O3 and Al/(Al + Fe + Mn) ratios. In figures of Fe–Mn–[(Ni+Cu+Co)×10] and lgU–lgTh, all samples show that hydrothermal exhalative fluids played an important role during mineralisation. The δ13CPDB and δ18OSMOW values of eight ore samples are from-20.7‰ to-8.2‰(with an average of-12.4‰) and from 14.3‰ to 18.7‰(with an average of 17.0‰), respectively. These carbon and oxygen isotopic features indicate that hydrothermal fluids derived from deep earth are participation in the metallogenic process, which is also supported by high paleo-seawater temperatures varying from 47.08 to 73.98 °C. Therefore, the geological and geochemical evidences show that the Qujiashan deposit formed from submarine exhalative hydrothermal sedimentation.
基金Project(2010CB226805) supported by the National Basic Research Program of ChinaProject(CXLX13-949) supported by the Research and Innovation Project for College Graduates of Jiangsu Province,China+1 种基金Project(51174285) supported by the National Natural Science Foundation of ChinaProject(SZBF2011-6-B35) supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘Considering the serious coal and rock dynamic disasters around the main slip plane called F16 in the coal mining area) of Henan Yima(China) thrust nappe structure,the mechanical genesis of the Yima thrust nappe structure was studied comprehensively using geomechanics,fault mechanics,elastic mechanics,and Coulomb's law of friction.First,using the centrifugal inertia force of Earth's rotation as a source,a mechanical model of N-S compression superimposed with W-E reverse torsion was established to explain the formation of the early Yima coal basin and Jurassic Yima Group coal measures.Second,an equation for the ultimate stress in the forming stage of F16 was derived using the plastic slip-line field theory and the parabolic Mohr failure criterion.Moreover,the distribution of ultimate stress and the geometric characteristics of the fault profile were obtained using the field model parameters.Finally,the stress field of F16 and the mechanical genesis of the large-scale reverse thrust sheet were discussed based on elastic mechanics theory and Coulomb's law of friction.The results show that the tectonic framework of the early Yima coal basin and the formation pattern of Jurassic Yima Group coal measures given by the model are consistent with the in-situ explorations.The geometric characteristics of the fault profile obtained by numerical calculation can better reflect the shape of F16 in its forming stage,and the mechanical genesis of the large-scale reverse thrust sheet also concurred with the field situations.Thus,this work can provide a foundation for further studies on the genesis of the thrust nappe structure,the mechanism of rock bursts induced by F16,and the characteristics of the residual stress field in the Yima mining area.
文摘The Kohistan Terrane in N. Pakistan straddles the suture zone between the collided Indian and Eurasian plates in the NW Himalayas of N. Pakistan. Initiated as an intra\|oceanic island\|arc crust in Neotethys, the terrane accreted with the southern margin of the Karakoram Plate in the Late Cretaceous (about 90Ma). Continued subduction at its southern margin resulted in Andean\|type magmatism and tectonics, until collision with the Indian Plat in the Early Eocene.Whereas much of the central and eastern Kohistan expose Cretaceous volcanic and sedimentary rocks of intra\|oceanic island arc setting, the western Kohistan in Swat, Dir, Chitral and upper Ghizer valleys preserves remnants of the Late Paleocene—Early Eocene volcanism and sedimentation of Andean\|type setting. These volcano\|sedimentary lithologies in western Kohistan are geographically divisible into two, separated by the Lowari Pluton; (1) Dir\|Swat Belt, (2) Drosh\|Shamran Belt. Late Paleocene\|Early Eocene siliceous volcanics termed Utror Volcanics and Shamran Volcanics are common in the two belts and so are the plutons intrusive into these volcanics (Late Stage\|II of the Kohistan Batholith). The difference is in the sedimentary successions presented in the two belts. Whereas in the Dir\|Swat belt, the sedimentary succession comprises Baraul Banda Slate Formation, deposited in deep\|water fore\|arc setting and contemporaneous in age with that of the nearby Utror Volcanic Formation (about 55～60Ma), the sediments in the Drosh\|Shamran belt are distinctly red beds of fluvial origin (the Purit Formation) those overlie unconformably on top of the Shamran Volcanics and their equivalents.
文摘The Yunnan Himalayan alkaline rich porphyry occurs as a compound rockbelt and consists of calca alkalic, alkaline and peralkaline intrusions. Its origin is in debate. The paper deals with its origin by studying rock′s REE and Sr isotope. Although the rocks are different in their REE contents varying from 77.53 μg/g to 1 798.3 μg/g, they have very similar features in REE parameters. On the triangalar diagram of REEs, the sample dots are concentrated on the end area of light REEs, representing a product of low degree melting of upper mantle or lower crust materials. The initial 87 Sr/ 86 Sr values of rocks vary between 0.706 4 and 0.709 8, showing a feature of mantle crust mixed source. Moreover, REEs show a logarithmic linear positive correlation between them. This type of correlation strongly supports the fractional partial melting model. The result of geochemistry inversion shows that the source rock of alkaline rich porphyry is plagioclase bearing harzburgite and of mantle crust mixed type. At the early state of melting, some crust components of the source rock were partially melted into intermediate acidic magma; with the crust components consumed, the magma evolved to basic.
文摘The Lala Cu deposit in Sichuan Province is one of the most important large deposits in SW China,both in terms of Cu and associated Au-Mo-Co-REE-Fe. Systematic ore petrology study shows that ore minerals are mainly composed of hydrothermal magnetite,chalcopyrite and molybdenite.The wall-rock alterations include biotitization,silicification, carbonatation,albitization,potash feldspathization, apatitation,actinolitation and fluoritation,et al. The Pyrite and magnetite have euhedral-subhedral crystalline grained texture and the chalcopyrite
文摘There are many skarn deposits that occur in volcanic rocks as stratiform and lentoid bodies,for example the Lower Yangtze River Valley,Western Tianshan Mountains and Lhasa Terrane in China,the Nuuk in West Greeland and the Austroalpine Alps(e.g.Xv et al.,1984;Appel,1994;Raith and Stein,2000;Wang et al.,2001;Gu et al.,2007;Hou et al.,2011;Zhou et al.,2011;Jiang et al.,2012;Xu et al.,2010;Wang et al.,2012;Yu et al.,2011).
