The Central Asian Orogenic Belt(CAOB)is one of the largest and best preserved accretionary type orogenic belts in the world.Due to its complex tectonic history,the timing and location of the final closure of the Paleo...The Central Asian Orogenic Belt(CAOB)is one of the largest and best preserved accretionary type orogenic belts in the world.Due to its complex tectonic history,the timing and location of the final closure of the Paleo-Asian Ocean and its tectonic evolution have been hotly discussed.To determine the petrogenesis and tectonic characteristics of the poorly exposed Triassic volcanic-intrusive complex on the northern margin of the eastern North China Craton,the authors conducted a study of zircon Lu-Hf isotopes,integrated with zircon U-Pb dating and whole-rock geochemistry.Zircons from eight representative volcanic and intrusive samples yielded concordant U-Pb ages of 251-245 Ma.The volcanic and intrusive rocks are all characterized by enrichments in large ion lithophile elements and depletions in high field strength elements,and they have features similar to those of highly fractionated Ⅰ-type granites.TheεHf(t)values for the volcanic and intrusive rocks,respectively,range from-1.69 to+3.75(mean=+1.22)and-2.17 to+3.15(mean=+0.38),with two-stage model ages of 1035-1345 Ma(mean=1196 Ma)and 1073-1401 Ma(mean=1250 Ma).The Hf isotopic features indicate that these rocks were formed by partial melting of young crustal material that was newly accreted from the depleted mantle,together with a degree of contamination by other crustal material.The volcanic-intrusive complex was related to an active continental margin in a volcanic arc and syn-collisional setting,indicating that the Paleo-Asian Ocean was closed after the Middle Triassic(245 Ma)along the northern margin of the North China Craton.This provides a constraint on the timing of the change in tectonic setting in this area from compression to extension.The results enhance our understanding of the evolution of the Paleo-Asian Ocean.展开更多
On the basis of previous studies and by means of field geological, remote sensing, petrographical,mineralogical, petrochemical and geochemical investigations, the authors studied the temporal-spatial distribu-tion of ...On the basis of previous studies and by means of field geological, remote sensing, petrographical,mineralogical, petrochemical and geochemical investigations, the authors studied the temporal-spatial distribu-tion of the regional structures, volcanic structures and products of volcanic activity in the coastal area ofsoutheastern Zhejiang. On the basis and through a systematic comparison of the products of magmatism in thearea, it is considered that there exists a compsite volcanic structural belt composed of linear and circular struc-tures and it has been demonstrated that there exist volcanic intrusive complexes--'trinity' composed of vol-canic, subvolcanic and plutonic rocks. It is suggested that the volcanic intrusive complexes in the area belong tothe typical syntexis series and that its materials were derived from a mixed source of crust and mantle.展开更多
Systematic zircon LA-ICPMS U-Pb dating reveals that Cretaceous volcanic-intrusive activities developed in western Guangdong. Representative volcanic rocks, i.e. Maanshan and Zhougongding rhyodacites, have zircon U-Pb ...Systematic zircon LA-ICPMS U-Pb dating reveals that Cretaceous volcanic-intrusive activities developed in western Guangdong. Representative volcanic rocks, i.e. Maanshan and Zhougongding rhyodacites, have zircon U-Pb isotopic ages of 100±1 Ma, and the intrusive ones in-cluding the Deqing monzonitic granite body and the Xinghua granodiorite body in the Shidong com-plex, as well as the Tiaocun granodiorite body in the Guangping complex yield ages of 99±2 Ma, ca. 100 Ma, and 104±3 Ma respectively. The biotite-granites of the Shidong complex main body (461±35 Ma) and that of the Guangping complex (444±6 Ma) are Caledonian. In spite of the big time interval between Cretaceous volcanic-intrusive magmatisms and Caledonian intrusive ones, both of them are characterized by enrichment in Rb, Th, Ce, Zr, Hf, Sm, depletion in Ba, Nb, Ta, P, Ti, Eu, and weakly REE tetrad effect. Eu negative anomalies are: Cretaceous volcanic rocks (Eu/Eu*=0.74), Cretaceous intrusive rocks (Eu/Eu*=0.35―0.58), Caledonian biotite granites (Eu/Eu*=0.31―0.34). Studies of Sr-Nd isotope data show that all these igneous rocks have high initial 87Sr/86Sr ratios (0.7105―0.7518), and low εNd(t) values (?7.23―?11.39) with their Nd two-stage model ages ranging from 1.6―2.0 Ga, which suggest that they all derived from the Proterozoic crustal basement of southeast China. The occurrence of Cretaceous volcanic-intrusive magmatisms in western Guangdong is related with the important lithospheric extension event in southeast China (including Nanling region) at ca. 100 Ma. The “volcanic line” defined by the large scale Mesozoic intermediate-acidic volcanic magmatisms in southeast China may further extend to the southwest margin of Nanling region.展开更多
A detailed study of isotope and trace element on the volcanic-intrusive complex in Yanbei, Jiangxi Province is reported.All rocks of the complex have similar crystallization age,relatively high(^(87)Sr/ ^(88)Sr)_i and...A detailed study of isotope and trace element on the volcanic-intrusive complex in Yanbei, Jiangxi Province is reported.All rocks of the complex have similar crystallization age,relatively high(^(87)Sr/ ^(88)Sr)_i and δ^(18)O,high ^(207)Pb/^(204)Pb,lower ε_(Nd)and old Nd model age.They also possess high Rb/Sr and F/ Cl,weak Ce and intense Eu negative anomalies.These characteristics clearly demonstrate that the volcanic- intrusive complex is the product of the evolution of cognate magma,and the initial magma was formed by the partial melting of Early-Middle Proterozoic metasedimentary rocks.展开更多
Mafic"intrusive rocks",distributed greatly within Dongchuan strata-bound copperfield and really comprising volcanic,subvolcanic and volcano plutonic rocks,should be termed as volcanic-intrusive complex(VIC)....Mafic"intrusive rocks",distributed greatly within Dongchuan strata-bound copperfield and really comprising volcanic,subvolcanic and volcano plutonic rocks,should be termed as volcanic-intrusive complex(VIC).Geology and geochemistry of Jinningian VIC and its relation to Cu ores reaffirm that VIC play an important role in mineralizations,which are not only vein bonanzas deduced from coose beds,but also new orebodies occurred within VIC.Bonanzas of superposing-reworking type and orebodies of magmatic liquation-differentiation type in the depth are suggested to be found in the largely developing VIC area.展开更多
The Cu - An co - existence ore deposits related to intermediate- acidic volcanic - intrusive complexes are widespread in eastern China. They can be divided into 5 types: (1) sharn type, (2 )porphyry type, (3)vein type...The Cu - An co - existence ore deposits related to intermediate- acidic volcanic - intrusive complexes are widespread in eastern China. They can be divided into 5 types: (1) sharn type, (2 )porphyry type, (3)vein type, (4 )breccia pipe type and (5)stratabound type. All of those have intimate spatial, temporal and genetic relations formed by the Mesozoic tertonicmatic - hydrothermal activities in certain geological environments. The magmatic and Cu-An metallogenic ager were predominately in Late Mesozoic (179-90 Ma), and in the period of 150-120 Ma the ore-forming Processes reached the Peak. The main geological Settings of Cu-An ore-forming Processes are: (1) continental margins, including the Peripheral depression of the continental Plate, (2) deep fault zones in the continental Plate,(3)continental rift belt. The magmatic activities were under the combined control of basement fault (s )and superficial fault (s ), and mostly formed the continental volcanic basins. The regional Cu-An metallogenic zones occur along the deep fault zones in WNW - EW direction,such as the Tongling metallogenic subzone, or in NE-NNE direction, such as the Dexing metallogenic subzone. Most of Cu- An ore deposits are related to subvolcanic stocks consist of quartz diorite, granodiorite, quartz porphyry, andesite porphyry, trachyte porphyry and other rocks, which belong to the calc- alkaline series and the I - type granitoid. The spatial zoning of matals from the center to periphery of the stocks is: CU (Mo )→ Cu,Au→Cu, Ph, Zn,An →Ph, Zn, Ag →Ph, Ag. There is a typical venical metallic zoning (from surface to 3 000m in depth ) in Yinshan Cu-An-Ph-Zn-Ag ore deposit, northeastern Jianxi Province.展开更多
基金supported by the National Natural Science Foundation of China(U2244213)the project from China Geological Survey(No.DD20160062)the fundamental research project from the Institute of Geomechanics,Chinese Academy of Geological Sciences(DZLXJK202307).
文摘The Central Asian Orogenic Belt(CAOB)is one of the largest and best preserved accretionary type orogenic belts in the world.Due to its complex tectonic history,the timing and location of the final closure of the Paleo-Asian Ocean and its tectonic evolution have been hotly discussed.To determine the petrogenesis and tectonic characteristics of the poorly exposed Triassic volcanic-intrusive complex on the northern margin of the eastern North China Craton,the authors conducted a study of zircon Lu-Hf isotopes,integrated with zircon U-Pb dating and whole-rock geochemistry.Zircons from eight representative volcanic and intrusive samples yielded concordant U-Pb ages of 251-245 Ma.The volcanic and intrusive rocks are all characterized by enrichments in large ion lithophile elements and depletions in high field strength elements,and they have features similar to those of highly fractionated Ⅰ-type granites.TheεHf(t)values for the volcanic and intrusive rocks,respectively,range from-1.69 to+3.75(mean=+1.22)and-2.17 to+3.15(mean=+0.38),with two-stage model ages of 1035-1345 Ma(mean=1196 Ma)and 1073-1401 Ma(mean=1250 Ma).The Hf isotopic features indicate that these rocks were formed by partial melting of young crustal material that was newly accreted from the depleted mantle,together with a degree of contamination by other crustal material.The volcanic-intrusive complex was related to an active continental margin in a volcanic arc and syn-collisional setting,indicating that the Paleo-Asian Ocean was closed after the Middle Triassic(245 Ma)along the northern margin of the North China Craton.This provides a constraint on the timing of the change in tectonic setting in this area from compression to extension.The results enhance our understanding of the evolution of the Paleo-Asian Ocean.
文摘On the basis of previous studies and by means of field geological, remote sensing, petrographical,mineralogical, petrochemical and geochemical investigations, the authors studied the temporal-spatial distribu-tion of the regional structures, volcanic structures and products of volcanic activity in the coastal area ofsoutheastern Zhejiang. On the basis and through a systematic comparison of the products of magmatism in thearea, it is considered that there exists a compsite volcanic structural belt composed of linear and circular struc-tures and it has been demonstrated that there exist volcanic intrusive complexes--'trinity' composed of vol-canic, subvolcanic and plutonic rocks. It is suggested that the volcanic intrusive complexes in the area belong tothe typical syntexis series and that its materials were derived from a mixed source of crust and mantle.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 40221301,40125007 and 40132010).
文摘Systematic zircon LA-ICPMS U-Pb dating reveals that Cretaceous volcanic-intrusive activities developed in western Guangdong. Representative volcanic rocks, i.e. Maanshan and Zhougongding rhyodacites, have zircon U-Pb isotopic ages of 100±1 Ma, and the intrusive ones in-cluding the Deqing monzonitic granite body and the Xinghua granodiorite body in the Shidong com-plex, as well as the Tiaocun granodiorite body in the Guangping complex yield ages of 99±2 Ma, ca. 100 Ma, and 104±3 Ma respectively. The biotite-granites of the Shidong complex main body (461±35 Ma) and that of the Guangping complex (444±6 Ma) are Caledonian. In spite of the big time interval between Cretaceous volcanic-intrusive magmatisms and Caledonian intrusive ones, both of them are characterized by enrichment in Rb, Th, Ce, Zr, Hf, Sm, depletion in Ba, Nb, Ta, P, Ti, Eu, and weakly REE tetrad effect. Eu negative anomalies are: Cretaceous volcanic rocks (Eu/Eu*=0.74), Cretaceous intrusive rocks (Eu/Eu*=0.35―0.58), Caledonian biotite granites (Eu/Eu*=0.31―0.34). Studies of Sr-Nd isotope data show that all these igneous rocks have high initial 87Sr/86Sr ratios (0.7105―0.7518), and low εNd(t) values (?7.23―?11.39) with their Nd two-stage model ages ranging from 1.6―2.0 Ga, which suggest that they all derived from the Proterozoic crustal basement of southeast China. The occurrence of Cretaceous volcanic-intrusive magmatisms in western Guangdong is related with the important lithospheric extension event in southeast China (including Nanling region) at ca. 100 Ma. The “volcanic line” defined by the large scale Mesozoic intermediate-acidic volcanic magmatisms in southeast China may further extend to the southwest margin of Nanling region.
文摘A detailed study of isotope and trace element on the volcanic-intrusive complex in Yanbei, Jiangxi Province is reported.All rocks of the complex have similar crystallization age,relatively high(^(87)Sr/ ^(88)Sr)_i and δ^(18)O,high ^(207)Pb/^(204)Pb,lower ε_(Nd)and old Nd model age.They also possess high Rb/Sr and F/ Cl,weak Ce and intense Eu negative anomalies.These characteristics clearly demonstrate that the volcanic- intrusive complex is the product of the evolution of cognate magma,and the initial magma was formed by the partial melting of Early-Middle Proterozoic metasedimentary rocks.
基金One part of the Nationar"Eight-Five"Key Science and Technology Program(85-901-04-04)。
文摘Mafic"intrusive rocks",distributed greatly within Dongchuan strata-bound copperfield and really comprising volcanic,subvolcanic and volcano plutonic rocks,should be termed as volcanic-intrusive complex(VIC).Geology and geochemistry of Jinningian VIC and its relation to Cu ores reaffirm that VIC play an important role in mineralizations,which are not only vein bonanzas deduced from coose beds,but also new orebodies occurred within VIC.Bonanzas of superposing-reworking type and orebodies of magmatic liquation-differentiation type in the depth are suggested to be found in the largely developing VIC area.
文摘The Cu - An co - existence ore deposits related to intermediate- acidic volcanic - intrusive complexes are widespread in eastern China. They can be divided into 5 types: (1) sharn type, (2 )porphyry type, (3)vein type, (4 )breccia pipe type and (5)stratabound type. All of those have intimate spatial, temporal and genetic relations formed by the Mesozoic tertonicmatic - hydrothermal activities in certain geological environments. The magmatic and Cu-An metallogenic ager were predominately in Late Mesozoic (179-90 Ma), and in the period of 150-120 Ma the ore-forming Processes reached the Peak. The main geological Settings of Cu-An ore-forming Processes are: (1) continental margins, including the Peripheral depression of the continental Plate, (2) deep fault zones in the continental Plate,(3)continental rift belt. The magmatic activities were under the combined control of basement fault (s )and superficial fault (s ), and mostly formed the continental volcanic basins. The regional Cu-An metallogenic zones occur along the deep fault zones in WNW - EW direction,such as the Tongling metallogenic subzone, or in NE-NNE direction, such as the Dexing metallogenic subzone. Most of Cu- An ore deposits are related to subvolcanic stocks consist of quartz diorite, granodiorite, quartz porphyry, andesite porphyry, trachyte porphyry and other rocks, which belong to the calc- alkaline series and the I - type granitoid. The spatial zoning of matals from the center to periphery of the stocks is: CU (Mo )→ Cu,Au→Cu, Ph, Zn,An →Ph, Zn, Ag →Ph, Ag. There is a typical venical metallic zoning (from surface to 3 000m in depth ) in Yinshan Cu-An-Ph-Zn-Ag ore deposit, northeastern Jianxi Province.
