Objective The Geza arc in Yunnan Province,located in the southern Yidun arc,is an important part of the Sanjiang tectonic-magmatic belts in southwestern China and is a newly discovered copper polymetallic ore-concentr...Objective The Geza arc in Yunnan Province,located in the southern Yidun arc,is an important part of the Sanjiang tectonic-magmatic belts in southwestern China and is a newly discovered copper polymetallic ore-concentrating district.Recent studies show that the newly discovered Yanshanian porphyry Cu-Mo polymetallic mineralization superimposed in the Indosinian porphyry copper belt in this area.展开更多
Evidence for a mantle and/or basaltic component in KT boundary distal ejecta is apparently inconsistent with ejection from Chicxulub Crater since it is located on;5km thick continental crust(De Paolo et al.,1983;Mont...Evidence for a mantle and/or basaltic component in KT boundary distal ejecta is apparently inconsistent with ejection from Chicxulub Crater since it is located on;5km thick continental crust(De Paolo et al.,1983;Montanari et al.,1983;Hildebrand and Boynton,1988,1990).Evidence for mafic/ultramafic target rocks was reinforced by discovery of chromites,some with shock planar deformation features(PDF),in impact layer samples from sites in southern Colorado and eastern Wyoming(Bohor et al.,1990).However,until now it was unclear whether the chromites originated with an impactor or with terrestrial target rocks.To this end,high-precision 54Cr/52Cr isotope ratios were measured on KT boundary chromites along with known terrestrial chromites.We find a terrestrial 54Cr/52Cr ratio in KT boundary chromites from impact layer samples collected at the above sites over the last several years(Fig.1).Ejected terrestrial chromites suggest the impact sampled terrestrial mafic and/or ultramafic target rocks not known to exist in the Chicxulub target area.展开更多
Objective The Mengyejing potash deposit in the Simao Basin is the only producing area of solid potash at present in China. There is still controversy about the material source and distribution of the potash in this d...Objective The Mengyejing potash deposit in the Simao Basin is the only producing area of solid potash at present in China. There is still controversy about the material source and distribution of the potash in this deposit (Shen Lijian et al., 2017), which has influenced not only the prospecting direction and efficiency but also the understanding of the control of Tethys tectonic evolution on the formation and distribution of the mineral resources. This work analyzed the Sr isotope geochemical characteristics of evaporites from core samples in the well MZK-3 in order to further clarify the material source and to explore the potash distribution in the Simao Basin.展开更多
Objective The Yangtze craton collisional orogeny at ca. extensional events at ca. 1 experienced Paleoproterozoic 1.95-2.0 Ga and post-orogenic 85 Ga related to amalgamation of the Columbia (Nuna) supercontinent (Zh...Objective The Yangtze craton collisional orogeny at ca. extensional events at ca. 1 experienced Paleoproterozoic 1.95-2.0 Ga and post-orogenic 85 Ga related to amalgamation of the Columbia (Nuna) supercontinent (Zhao and Cawood, 2012). A ca. 2.15 Ga suprasubduction zone ophiolitic melange was recongized in the Archean- Paleoproterozoic Kongling Complex of the northern Yangtze craton (Han et al., 2017). However, the tectonic evolution in early Paleoproterozoic from 2.4 Ga to 2.2 Ga remains unclear. We report here the presence of a suite of Paleoproterozoic (2.2 Ga) granites in the Huangling dome, northern Yangtze craton, which may provide important insights into crustal growth processes in the craton prior to the assembly of Columbia.展开更多
Objective As the uplift belt on the southem margin of the Tarim block, the Tiekelike block consists mainly of a set of Precambrian metamorphic rocks with granulite and gneisses. The Heluositan group-complex is the mo...Objective As the uplift belt on the southem margin of the Tarim block, the Tiekelike block consists mainly of a set of Precambrian metamorphic rocks with granulite and gneisses. The Heluositan group-complex is the most ancient rock series in the area, and is a key area for studying the formation and evolution of the Precambrian basement of the Tarim craton. LA-ICP-MS zircon U-Pb dating and Hf isotopic analysis of granulite in this area provide new evidence for revealing the formation and evolution of the Precambrian basement in the Tarim Basin.展开更多
The Central Asian Orogenic Belt(CAOB)is one of the largest Phanerozoic accretionary orogen.(Windley et al.,1990,2007;Jahn et al.,2000a,b,c;Yakubchuk,2002,2004;Xiao et al.,2003,2004).It is the optimal study area fo...The Central Asian Orogenic Belt(CAOB)is one of the largest Phanerozoic accretionary orogen.(Windley et al.,1990,2007;Jahn et al.,2000a,b,c;Yakubchuk,2002,2004;Xiao et al.,2003,2004).It is the optimal study area for revealing the accretion and reworking processes of the continental crust.The Khanka Massif is located in the most eastern part of the CAOB,and mainly crops out in the territory of Russia,with a small segment in NE China.In addition,a large number of multi-stage granitic rocks are formed in geological evolution in this area,recording amounts of information about crustal accretion and reworking processes(De Paolo et al.,1991;Rudnick,1995;Wu et al.,2011).In view of this,this paper uses the spatial-temporal variations of trace elements and zircon Hf isotopic compositions of phanerozoic granitoids within the Khanka Massif as a case to reveal the crustal accretion and reworking processes of micro continental massifs from the orogenic belt,further to understand the formation and evolution processes and mechanisms of the global continental crust.According to the statistics of zircon U-Pb ages of granitoids in the Khanka Massif,indicate that the granitic magmatisms in the Khanka Massif have eleven peaks:492 Ma,460 Ma,445Ma,430Ma,425Ma,302Ma,287Ma,258Ma,249 Ma,216Ma and 213Ma,it can be divided into eight main stages:Late Cambrian,Middle-Late Ordovician,Middle Silurian,Late Carboniferous,EarlyPermian,Middle-Late Permian—Early Triassic,Late Triassic-Early Jurassic,Early Cretaceous.The Phanerozoic granitoids in Khanka massif are selectedinthispaperasasuiteof granodiorite-monzogranite-syenogranite.TheSi O2contents of the Phanerozoic granitoids exceed 65%,and has high Al2O3,low Mg#,TFe2O3,Cr,Co and Ni contents.This suggests that mixture with mantle-derived magma did not occur,and it should be a typical crustal source(Lu and Xu,2011).Combined with evident characteristics of light rare-earth elements(LREEs)and large ion lithophile elements(LILEs)enrichment,and heavy rare-earth elements(HREEs)and high field-strength elements(HFSEs)loss,we suggest that the primary magma was derived by partial melting of lower crustal material(Xu et al.,2009),and geochemical properties of the Phanerozoic granitoids essentially reflect the nature of the magmatic source region.According to the temporal variation of zircon Hf isotopic data of Phanerozoic granitioids,zircon Hf isotopic compositions of Phanerozoic granitoids have a obvious correlation with age.With the decrease of formation time ofthePhanerozoicgranitoids(Late Cambrian;iddle-LateOrdovician;iddle Silurian;arlyPermian;iddle-LatePermian–Early Triassic;ate Triassic-Early Jurassic),εHf(t)values of zircons gradually increase,whereas their TDM2 ages gradually decrease(Paleoproterozoic–Neoproterozoic),suggesting that the generation of granitic magmas from the Khanka Massif could have experienced the change from the melting of the ancient crust to the juvenile crust during Paleozoic to Mesozoic.According to the sample location,it can be found thatεHf(t)values of Phanerozoic granitoids have the tendency to decrease with latitude increase,showing that components of the ancient continental crust gradually increase from south to north.However,at the same latitude range,theεHf(t)values of Phanerozoic granitoids also inconsistent.Taken together,these differences reveal the horizontal and vertical heterogeneity of the lower continental crust within the Khanka Massif.According to the relative probability of two-stage model(TDM2)ages of zircon Hf isotope from Phanerozoic granitoids within the Khanka massif,it could be divided into three stages:(1)Late Paleoproterozoic(2)Mesoproterozoic(3)Neoproterozoic.It reveals that the main part of the continental crust within the Khanka MassifwereformedinLate Paleoproterozoic–Neoproterozoic.The Phanerozoic granitoids in the Khanka Massif reworked from the source rockswithdifferent ages(Paleoproterozoic–Mesoproterozoic–Neoproterozoic).展开更多
The Dashuigou tellurium deposit found in 1991 in Shimian County, Sichuan Province of China, is the first and only independent tellurium deposit in the world. The deposit is located on the western margin of the Yangtze...The Dashuigou tellurium deposit found in 1991 in Shimian County, Sichuan Province of China, is the first and only independent tellurium deposit in the world. The deposit is located on the western margin of the Yangtze Platform. The tellurium ore bodies taking vein and lentiform shapes filled the N-S fractures in the pyrrhotite veins in hornblende schists at the northern limb of the Middle and Lower Triassic metamorphic arch. The main wallrock alterations are biotitization, sericitization, greisenization, dolomitization,展开更多
基金financially supported by the National Natural Science Foundation of China (grant No.41502076)the Leading Talents Plan Project of Science and Technology of Yunnan Province (grant No.2013HA001)the Science Research Fund of Yunnan Provincial Education Department (grant No.2015Y066)
文摘Objective The Geza arc in Yunnan Province,located in the southern Yidun arc,is an important part of the Sanjiang tectonic-magmatic belts in southwestern China and is a newly discovered copper polymetallic ore-concentrating district.Recent studies show that the newly discovered Yanshanian porphyry Cu-Mo polymetallic mineralization superimposed in the Indosinian porphyry copper belt in this area.
文摘Evidence for a mantle and/or basaltic component in KT boundary distal ejecta is apparently inconsistent with ejection from Chicxulub Crater since it is located on;5km thick continental crust(De Paolo et al.,1983;Montanari et al.,1983;Hildebrand and Boynton,1988,1990).Evidence for mafic/ultramafic target rocks was reinforced by discovery of chromites,some with shock planar deformation features(PDF),in impact layer samples from sites in southern Colorado and eastern Wyoming(Bohor et al.,1990).However,until now it was unclear whether the chromites originated with an impactor or with terrestrial target rocks.To this end,high-precision 54Cr/52Cr isotope ratios were measured on KT boundary chromites along with known terrestrial chromites.We find a terrestrial 54Cr/52Cr ratio in KT boundary chromites from impact layer samples collected at the above sites over the last several years(Fig.1).Ejected terrestrial chromites suggest the impact sampled terrestrial mafic and/or ultramafic target rocks not known to exist in the Chicxulub target area.
基金supported by the"national Key R&D Program of China"(grant No.2017YFC0602801)geological survey project of"Investigation and Evaluation of the Potash Deposit Prospect in West China"(grant No.DD20160054)
文摘Objective The Mengyejing potash deposit in the Simao Basin is the only producing area of solid potash at present in China. There is still controversy about the material source and distribution of the potash in this deposit (Shen Lijian et al., 2017), which has influenced not only the prospecting direction and efficiency but also the understanding of the control of Tethys tectonic evolution on the formation and distribution of the mineral resources. This work analyzed the Sr isotope geochemical characteristics of evaporites from core samples in the well MZK-3 in order to further clarify the material source and to explore the potash distribution in the Simao Basin.
基金supported by the funded project of the China Geological Survey(grants No.12120113061700,121201009000150013 and DD20160029)
文摘Objective The Yangtze craton collisional orogeny at ca. extensional events at ca. 1 experienced Paleoproterozoic 1.95-2.0 Ga and post-orogenic 85 Ga related to amalgamation of the Columbia (Nuna) supercontinent (Zhao and Cawood, 2012). A ca. 2.15 Ga suprasubduction zone ophiolitic melange was recongized in the Archean- Paleoproterozoic Kongling Complex of the northern Yangtze craton (Han et al., 2017). However, the tectonic evolution in early Paleoproterozoic from 2.4 Ga to 2.2 Ga remains unclear. We report here the presence of a suite of Paleoproterozoic (2.2 Ga) granites in the Huangling dome, northern Yangtze craton, which may provide important insights into crustal growth processes in the craton prior to the assembly of Columbia.
基金supported by Xinjiang Uygur Autonomous Region 1:50000 special funds to support the transfer(grant No.1212011140056)
文摘Objective As the uplift belt on the southem margin of the Tarim block, the Tiekelike block consists mainly of a set of Precambrian metamorphic rocks with granulite and gneisses. The Heluositan group-complex is the most ancient rock series in the area, and is a key area for studying the formation and evolution of the Precambrian basement of the Tarim craton. LA-ICP-MS zircon U-Pb dating and Hf isotopic analysis of granulite in this area provide new evidence for revealing the formation and evolution of the Precambrian basement in the Tarim Basin.
文摘The Central Asian Orogenic Belt(CAOB)is one of the largest Phanerozoic accretionary orogen.(Windley et al.,1990,2007;Jahn et al.,2000a,b,c;Yakubchuk,2002,2004;Xiao et al.,2003,2004).It is the optimal study area for revealing the accretion and reworking processes of the continental crust.The Khanka Massif is located in the most eastern part of the CAOB,and mainly crops out in the territory of Russia,with a small segment in NE China.In addition,a large number of multi-stage granitic rocks are formed in geological evolution in this area,recording amounts of information about crustal accretion and reworking processes(De Paolo et al.,1991;Rudnick,1995;Wu et al.,2011).In view of this,this paper uses the spatial-temporal variations of trace elements and zircon Hf isotopic compositions of phanerozoic granitoids within the Khanka Massif as a case to reveal the crustal accretion and reworking processes of micro continental massifs from the orogenic belt,further to understand the formation and evolution processes and mechanisms of the global continental crust.According to the statistics of zircon U-Pb ages of granitoids in the Khanka Massif,indicate that the granitic magmatisms in the Khanka Massif have eleven peaks:492 Ma,460 Ma,445Ma,430Ma,425Ma,302Ma,287Ma,258Ma,249 Ma,216Ma and 213Ma,it can be divided into eight main stages:Late Cambrian,Middle-Late Ordovician,Middle Silurian,Late Carboniferous,EarlyPermian,Middle-Late Permian—Early Triassic,Late Triassic-Early Jurassic,Early Cretaceous.The Phanerozoic granitoids in Khanka massif are selectedinthispaperasasuiteof granodiorite-monzogranite-syenogranite.TheSi O2contents of the Phanerozoic granitoids exceed 65%,and has high Al2O3,low Mg#,TFe2O3,Cr,Co and Ni contents.This suggests that mixture with mantle-derived magma did not occur,and it should be a typical crustal source(Lu and Xu,2011).Combined with evident characteristics of light rare-earth elements(LREEs)and large ion lithophile elements(LILEs)enrichment,and heavy rare-earth elements(HREEs)and high field-strength elements(HFSEs)loss,we suggest that the primary magma was derived by partial melting of lower crustal material(Xu et al.,2009),and geochemical properties of the Phanerozoic granitoids essentially reflect the nature of the magmatic source region.According to the temporal variation of zircon Hf isotopic data of Phanerozoic granitioids,zircon Hf isotopic compositions of Phanerozoic granitoids have a obvious correlation with age.With the decrease of formation time ofthePhanerozoicgranitoids(Late Cambrian;iddle-LateOrdovician;iddle Silurian;arlyPermian;iddle-LatePermian–Early Triassic;ate Triassic-Early Jurassic),εHf(t)values of zircons gradually increase,whereas their TDM2 ages gradually decrease(Paleoproterozoic–Neoproterozoic),suggesting that the generation of granitic magmas from the Khanka Massif could have experienced the change from the melting of the ancient crust to the juvenile crust during Paleozoic to Mesozoic.According to the sample location,it can be found thatεHf(t)values of Phanerozoic granitoids have the tendency to decrease with latitude increase,showing that components of the ancient continental crust gradually increase from south to north.However,at the same latitude range,theεHf(t)values of Phanerozoic granitoids also inconsistent.Taken together,these differences reveal the horizontal and vertical heterogeneity of the lower continental crust within the Khanka Massif.According to the relative probability of two-stage model(TDM2)ages of zircon Hf isotope from Phanerozoic granitoids within the Khanka massif,it could be divided into three stages:(1)Late Paleoproterozoic(2)Mesoproterozoic(3)Neoproterozoic.It reveals that the main part of the continental crust within the Khanka MassifwereformedinLate Paleoproterozoic–Neoproterozoic.The Phanerozoic granitoids in the Khanka Massif reworked from the source rockswithdifferent ages(Paleoproterozoic–Mesoproterozoic–Neoproterozoic).
文摘The Dashuigou tellurium deposit found in 1991 in Shimian County, Sichuan Province of China, is the first and only independent tellurium deposit in the world. The deposit is located on the western margin of the Yangtze Platform. The tellurium ore bodies taking vein and lentiform shapes filled the N-S fractures in the pyrrhotite veins in hornblende schists at the northern limb of the Middle and Lower Triassic metamorphic arch. The main wallrock alterations are biotitization, sericitization, greisenization, dolomitization,