Lithium is one of the important strategic energy metals,which is in short supply in China.There are three major types of lithium deposits:brine and salt lake type,highly differentiated granite or pegmatite type,and ca...Lithium is one of the important strategic energy metals,which is in short supply in China.There are three major types of lithium deposits:brine and salt lake type,highly differentiated granite or pegmatite type,and carbonate-clay type.In recent years,some new types of lithium deposits have also begun to receive great attention and subject recent research.There are many crypto-explosive breccia pipe type deposits in the world,including copper,gold,lead,zinc,tungsten and tin deposits,but little is known about this type of lithium deposit.This paper introduces the latest research results of the Weilasituo Sn-Li-Rb polymetallic deposit in Inner Mongolia(NE China),which occurs in the middlesouthern section of the Great Xing’an Range metallogenic belt.A remarkable feature of this deposit is the coexistence of various mineralization types,including granite type Rb and Sn-Zn,hydrothermal crypto-explosive breccia pipe type Li-Rb,quartz vein type Sn-Zn and sulfide vein type Pb-Zn-Ag mineralization.Among them,hydrothermal crypto-explosive breccia pipe type Li-Rb deposit is currently very rare at home and abroad,which is likely a new type of rare metal deposit that worthy of our attention.This paper systematically summarizes the geology,alteration and mineralization,geochemistry,isotopes and geochronology of the Weilasituo deposit,and establishes a new petrogenic and metallogenic model.展开更多
To investigate the mechanical failure characteristics of volcanic breccia with different bedding dip angles in deep layers,triaxial compression experiments were conducted on specimens taken from volcanic rock layers i...To investigate the mechanical failure characteristics of volcanic breccia with different bedding dip angles in deep layers,triaxial compression experiments were conducted on specimens taken from volcanic rock layers in the Junggar Basin,Xinjiang.By changing the confining pressure,we compared the mechanical properties,acoustic emission characteristics,and fractal features of the acoustic emission sequence for volcanic breccia with different bedding dip angles.The research results indicate that as the bedding dip angle increases,peak strength,internal friction angle,and cohesion exhibit a“U-shaped”variation pattern.The correlation dimension of the acoustic emission amplitude was calculated using the G-P algorithm,revealing that volcanic breccia exhibits fractal characteristics.Furthermore,a positive correlation between the correlation dimension and the bedding dip angle was observed.When the stress of the test specimen reaches 0.8σ_(c),there is a significant decrease in the fractal dimension,serving as a criterion for predicting the failure of the specimen.By analyzing the changes in fractal dimension at different stress levels,the slope of the fractal dimension△D<-0.5 can be used as a precursor to failure for test specimens with a bedding dip angle of 15°≤β≤45°.Similarly,when the bedding dip angle of the specimen is 0°≤β<15°or 45°<β≤90°,△D<0 can be considered as a precursor to specimen failure.This study provides theoretical references for understanding the failure patterns of volcanic rock.展开更多
The Hongshan porphyry-cryptoexplosive breccia type copper deposit occurs in a metamorphic rock series of the Mesoproterozoic Zhongcun Group. Orebodies are distributed inside and outside porphyry-cryptoexplosive brecci...The Hongshan porphyry-cryptoexplosive breccia type copper deposit occurs in a metamorphic rock series of the Mesoproterozoic Zhongcun Group. Orebodies are distributed inside and outside porphyry-cryptoexplosive breccia pipes. The deposit involves five ore-forming types, i.e the porphyry type, cryptoexplosive breccia type, contact-zone veinlet-disseminated type, in-pipe fracture-zone filling-replacement type and out-of-pipe fracture-zone filling-replacement type, forming an ore-forming system of “five ore-forming types within a single rock body”. Fluid inclusion and isotope geochemical studies indicate the following: S, Pb, O and Sr were derived from the lower crust, Nd was derived from the continental crust or depleted mantle and rare earth elements (REE) and trace elements have the crustal source characters; fluids consist dominantly of formation water, metamorphic water and ***meteoric water with a part of magmatic mater, heat came from porphyry while the latter originated from partial melting caused by shear heating in the lower crust and upper mantle. According to its origin the deposit is classified as the hypabyssal and near-surface, meso- and hypothermal copper deposit associated with the late Yanshanian porphyry-cryptoexplosive breccia.展开更多
Fluidization processes based on experiments are reviewed to gain some useful insights and comparisons with those that occur in hydrothermal systems. Field and petrographic work, and microscope observation were carried...Fluidization processes based on experiments are reviewed to gain some useful insights and comparisons with those that occur in hydrothermal systems. Field and petrographic work, and microscope observation were carried out on samples from the Qiyugou Au-bearing breccia pipes from the East Qinling region, Henan Province. Evidence from macro- and micro-textures suggests that the style of breccias in the Qiyugou area can be grouped into three types： （1） jigsaw fit-stockwork texture, in which the interval between clasts is marked by fractures or filled with calcite or quartz veins; （2） larger breccias that are supported by smaller breccias, rock flour and alteration materials; in this type clasts moved over short distances, creating open spaces; （3） fluidized texture, where the clasts of different lithologies have rounded shapes. These observations are compared with those resulting from experiments on fluidization processes. The results of this comparison suggest that fluidization is an important geological process in the formation of the Qiyugou Au-bearing breccia pipes and gold mineralization. In addition, fluidization processes such as expansion, bubbling, slugging, channeling and spouting must have contributed to the formation of the pipes and were conducive to the development of gold mineralization. In the Qiyugou breccia pipes, gold mineralization occurs as disseminations, in stockwork veins, and open space infills. The ore zones form subparallel sheets that are nearly perpendicular to the walls of the pipes.展开更多
The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely devel...The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely developed breccias, and the ore-forming process have been carefully studied based on geological documentation of drilling holes, microscopic observations of petrography and microstructure and some stable isotope measurements.Based on the compositions of the clast and matrix, the breccias can be classified into three types： limestone clasts cemented by marl; limestone clasts with fine-grained calcareous materials; and limestone clasts cemented by hydrothermal calcite.The mineralization in the first type of breccia is weak, whereas it is strong in the latter two types of breccias.According to the locations of occurrence and structural characteristics of the breccias along with the relationship between the breccias and mineralization, part of the limestone clasts that are cemented by marl and outcrop in the contact zone between the Wudaoliang Formation（Nw） and the underlying Jiushidaoban Formation（Pj） are attributed to synsedimentary fault-genetic breccia, whereas the last of the limestone clasts that are cemented by marl and developed in the Jiushidaoban Formation（Pj） are attributed to the breccia generated by karst cave collapse; the limestone clasts with fine-grained calcareous materials and the limestone clasts cemented by hydrothermal calcite are attributed to breccia formed by hydrothermal dissolution.The breccia formed by karst collapse had consistently evolved for a long period of time, while the breccias with other origins were formed around the period of mineralization（i.e., about or slightly later than 20–16 Ma）.The breccia generated by karst cave collapse and hydrothermal dissolution are somewhat related; the formation of the breccia from karst cave collapse provided open space for the later mineralization and reaction between hydrothermal fluids and host rocks, and the subsequent strong dissolution by hydrothermal fluids transformed some of the breccia formed earlier by karst cave collapse.Meanwhile, carbonate host rocks with breccias and brecciaed mineralization can be a potential sign of Mississippi Valley Type（MVT） deposits and important indicators for regional mineral exploration.The δ13CV-PDB, δ18OVSMOW, and 87Sr/86 Sr values of hydrothermal calcite in the Duocaima deposit range from 4.3‰ to 7.1‰, 14.9‰ to 20.1‰, and 0.707494 to 0.708185, respectively; the δ13CV-PDB, δ18OV-SMOW, and 87Sr/86 Sr values of the host limestones of the Jiushidaoban Formation range from 3.6‰ to 5.3‰, 18.0‰ to 20.5‰, and 0.707372 to 0.707945, respectively.The δ13CV-PDB and 87Sr/86 Sr values of hydrothermal calcite and limestone are similar, indicating single sources of C and Sr in this deposit, with the likely source being the limestone of the Jiushidaoban Formation.The minor scattering of the δ18OV-SMOW values suggests that different O isotope fluids underwent the isotope exchange reaction.The C-O-Sr isotope characteristics indicate that the host limestones experienced a dissolution and precipitation process during mineralization, which is beneficial to improving the porosity of host rocks and promoting the precipitation of metal sulfides.The δ34SV-CDT value of the breccia-type mineralization sulfides ranges from-30.4‰ to-0.3‰; that is, the δ34SV-CDT value is negative with considerable variation, illustrating that during the breccia-type mineralization process, the bacteriogenic reduction of sulfates provided the vast majority of sulfur, whereas the thermochemical reduction of sulfates was relatively unimportant.The brecciation that occurred as a result of karst cave collapse was mainly generated by the dissolution of groundwater; however, the brecciation related to hydrothermal dissolution and mineralization processes were caused by mixing of different fluids.展开更多
基金financially supported by projects from the National Natural Science Foundation of China(No.92162323)the National Key R&D Program of China(No.2017YFC0602405)。
文摘Lithium is one of the important strategic energy metals,which is in short supply in China.There are three major types of lithium deposits:brine and salt lake type,highly differentiated granite or pegmatite type,and carbonate-clay type.In recent years,some new types of lithium deposits have also begun to receive great attention and subject recent research.There are many crypto-explosive breccia pipe type deposits in the world,including copper,gold,lead,zinc,tungsten and tin deposits,but little is known about this type of lithium deposit.This paper introduces the latest research results of the Weilasituo Sn-Li-Rb polymetallic deposit in Inner Mongolia(NE China),which occurs in the middlesouthern section of the Great Xing’an Range metallogenic belt.A remarkable feature of this deposit is the coexistence of various mineralization types,including granite type Rb and Sn-Zn,hydrothermal crypto-explosive breccia pipe type Li-Rb,quartz vein type Sn-Zn and sulfide vein type Pb-Zn-Ag mineralization.Among them,hydrothermal crypto-explosive breccia pipe type Li-Rb deposit is currently very rare at home and abroad,which is likely a new type of rare metal deposit that worthy of our attention.This paper systematically summarizes the geology,alteration and mineralization,geochemistry,isotopes and geochronology of the Weilasituo deposit,and establishes a new petrogenic and metallogenic model.
基金funded by the National Natural Science Foundation of China(Grant Nos.52174096,42277174).
文摘To investigate the mechanical failure characteristics of volcanic breccia with different bedding dip angles in deep layers,triaxial compression experiments were conducted on specimens taken from volcanic rock layers in the Junggar Basin,Xinjiang.By changing the confining pressure,we compared the mechanical properties,acoustic emission characteristics,and fractal features of the acoustic emission sequence for volcanic breccia with different bedding dip angles.The research results indicate that as the bedding dip angle increases,peak strength,internal friction angle,and cohesion exhibit a“U-shaped”variation pattern.The correlation dimension of the acoustic emission amplitude was calculated using the G-P algorithm,revealing that volcanic breccia exhibits fractal characteristics.Furthermore,a positive correlation between the correlation dimension and the bedding dip angle was observed.When the stress of the test specimen reaches 0.8σ_(c),there is a significant decrease in the fractal dimension,serving as a criterion for predicting the failure of the specimen.By analyzing the changes in fractal dimension at different stress levels,the slope of the fractal dimension△D<-0.5 can be used as a precursor to failure for test specimens with a bedding dip angle of 15°≤β≤45°.Similarly,when the bedding dip angle of the specimen is 0°≤β<15°or 45°<β≤90°,△D<0 can be considered as a precursor to specimen failure.This study provides theoretical references for understanding the failure patterns of volcanic rock.
文摘The Hongshan porphyry-cryptoexplosive breccia type copper deposit occurs in a metamorphic rock series of the Mesoproterozoic Zhongcun Group. Orebodies are distributed inside and outside porphyry-cryptoexplosive breccia pipes. The deposit involves five ore-forming types, i.e the porphyry type, cryptoexplosive breccia type, contact-zone veinlet-disseminated type, in-pipe fracture-zone filling-replacement type and out-of-pipe fracture-zone filling-replacement type, forming an ore-forming system of “five ore-forming types within a single rock body”. Fluid inclusion and isotope geochemical studies indicate the following: S, Pb, O and Sr were derived from the lower crust, Nd was derived from the continental crust or depleted mantle and rare earth elements (REE) and trace elements have the crustal source characters; fluids consist dominantly of formation water, metamorphic water and ***meteoric water with a part of magmatic mater, heat came from porphyry while the latter originated from partial melting caused by shear heating in the lower crust and upper mantle. According to its origin the deposit is classified as the hypabyssal and near-surface, meso- and hypothermal copper deposit associated with the late Yanshanian porphyry-cryptoexplosive breccia.
基金the National Natural Science Foundation of China （grant No. 40032010B）.
文摘Fluidization processes based on experiments are reviewed to gain some useful insights and comparisons with those that occur in hydrothermal systems. Field and petrographic work, and microscope observation were carried out on samples from the Qiyugou Au-bearing breccia pipes from the East Qinling region, Henan Province. Evidence from macro- and micro-textures suggests that the style of breccias in the Qiyugou area can be grouped into three types： （1） jigsaw fit-stockwork texture, in which the interval between clasts is marked by fractures or filled with calcite or quartz veins; （2） larger breccias that are supported by smaller breccias, rock flour and alteration materials; in this type clasts moved over short distances, creating open spaces; （3） fluidized texture, where the clasts of different lithologies have rounded shapes. These observations are compared with those resulting from experiments on fluidization processes. The results of this comparison suggest that fluidization is an important geological process in the formation of the Qiyugou Au-bearing breccia pipes and gold mineralization. In addition, fluidization processes such as expansion, bubbling, slugging, channeling and spouting must have contributed to the formation of the pipes and were conducive to the development of gold mineralization. In the Qiyugou breccia pipes, gold mineralization occurs as disseminations, in stockwork veins, and open space infills. The ore zones form subparallel sheets that are nearly perpendicular to the walls of the pipes.
基金funded by National Nature Science Foundation of China (41273050, 41320104004)National Key Technology R&D Program in the 11th Five year Plan of China (No.2006 BAB01A08)the Geological Survey Project of China (12120114010301, 1212011220908)
文摘The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely developed breccias, and the ore-forming process have been carefully studied based on geological documentation of drilling holes, microscopic observations of petrography and microstructure and some stable isotope measurements.Based on the compositions of the clast and matrix, the breccias can be classified into three types： limestone clasts cemented by marl; limestone clasts with fine-grained calcareous materials; and limestone clasts cemented by hydrothermal calcite.The mineralization in the first type of breccia is weak, whereas it is strong in the latter two types of breccias.According to the locations of occurrence and structural characteristics of the breccias along with the relationship between the breccias and mineralization, part of the limestone clasts that are cemented by marl and outcrop in the contact zone between the Wudaoliang Formation（Nw） and the underlying Jiushidaoban Formation（Pj） are attributed to synsedimentary fault-genetic breccia, whereas the last of the limestone clasts that are cemented by marl and developed in the Jiushidaoban Formation（Pj） are attributed to the breccia generated by karst cave collapse; the limestone clasts with fine-grained calcareous materials and the limestone clasts cemented by hydrothermal calcite are attributed to breccia formed by hydrothermal dissolution.The breccia formed by karst collapse had consistently evolved for a long period of time, while the breccias with other origins were formed around the period of mineralization（i.e., about or slightly later than 20–16 Ma）.The breccia generated by karst cave collapse and hydrothermal dissolution are somewhat related; the formation of the breccia from karst cave collapse provided open space for the later mineralization and reaction between hydrothermal fluids and host rocks, and the subsequent strong dissolution by hydrothermal fluids transformed some of the breccia formed earlier by karst cave collapse.Meanwhile, carbonate host rocks with breccias and brecciaed mineralization can be a potential sign of Mississippi Valley Type（MVT） deposits and important indicators for regional mineral exploration.The δ13CV-PDB, δ18OVSMOW, and 87Sr/86 Sr values of hydrothermal calcite in the Duocaima deposit range from 4.3‰ to 7.1‰, 14.9‰ to 20.1‰, and 0.707494 to 0.708185, respectively; the δ13CV-PDB, δ18OV-SMOW, and 87Sr/86 Sr values of the host limestones of the Jiushidaoban Formation range from 3.6‰ to 5.3‰, 18.0‰ to 20.5‰, and 0.707372 to 0.707945, respectively.The δ13CV-PDB and 87Sr/86 Sr values of hydrothermal calcite and limestone are similar, indicating single sources of C and Sr in this deposit, with the likely source being the limestone of the Jiushidaoban Formation.The minor scattering of the δ18OV-SMOW values suggests that different O isotope fluids underwent the isotope exchange reaction.The C-O-Sr isotope characteristics indicate that the host limestones experienced a dissolution and precipitation process during mineralization, which is beneficial to improving the porosity of host rocks and promoting the precipitation of metal sulfides.The δ34SV-CDT value of the breccia-type mineralization sulfides ranges from-30.4‰ to-0.3‰; that is, the δ34SV-CDT value is negative with considerable variation, illustrating that during the breccia-type mineralization process, the bacteriogenic reduction of sulfates provided the vast majority of sulfur, whereas the thermochemical reduction of sulfates was relatively unimportant.The brecciation that occurred as a result of karst cave collapse was mainly generated by the dissolution of groundwater; however, the brecciation related to hydrothermal dissolution and mineralization processes were caused by mixing of different fluids.
