Plate subduction leads to complex exhumation processes on continents.The Huangling Massif lies at the northern margin of the South China Block.Whether the Huangling Massif was exhumed as a watershed of the middle reac...Plate subduction leads to complex exhumation processes on continents.The Huangling Massif lies at the northern margin of the South China Block.Whether the Huangling Massif was exhumed as a watershed of the middle reaches of the Paleo-Yangtze River during the Mesozoic remains under debate.We examined the exhumation history of the Huangling Massif based on six granite bedrock samples,using apatite fission track(AFT)and apatite and zircon(U-Th)/He(AHe and ZHe)thermochronology.These samples yielded ages of 157–132 Ma(ZHe),119–106 Ma(AFT),and 114–72 Ma(AHe),respectively.Thermal modeling revealed that three phases of rapid cooling occurred during the Late Jurassic–Early Cretaceous,late Early Cretaceous,and Late Cretaceous.These exhumation processes led to the high topographic relief responsible for the emergence of the Huangling Massif.The integrated of our new data with published sedimentological records suggests that the Huangling Massif might have been the watershed of the middle reaches of the Paleo-Yangtze River since the Cretaceous.At that time,the rivers flowed westward into the Sichuan Basin and eastward into the Jianghan Basin.The subduction of the Pacific Plate beneath the Asian continent in the Mesozoic deeply influenced the geomorphic evolution of the South China Block.展开更多
The Boya-02 kimberlite was identified at depth by geophysical survey work (a single-probe AM survey in 1997 and a gravity survey in 2006) that De Beers DRC Exploration carried out around anomaly 193/172/0019. This ano...The Boya-02 kimberlite was identified at depth by geophysical survey work (a single-probe AM survey in 1997 and a gravity survey in 2006) that De Beers DRC Exploration carried out around anomaly 193/172/0019. This anomaly located approximately 50 km southwest of the town of Mbuji-Mayi in the Kasaï-Oriental Province in the DRC should therefore be the subject of detailed exploration with the aim of better identifying and describing this kimberlite. Thus, through exploratory work and cross-checking of geophysical and geological data, the discovery of this Massif was made by drilling on the aeromagnetic anomaly 193/172/X298. Based on drilling, sampling and laboratory petrographic analysis reports, the Boya-02 kimberlite was classified among highly diluted re-sedimented volcaniclastic kimberlites (KVR), rich in olivine and incidentally in quartz and poor in juvenile substances. This kimberlite represents a deposit of very low economic interest following extremely high dilution. The Boya-02 kimberlite was modeled using ground magnetism data. It is a complex anomaly comprising 2 components with variable amplitude appearing on a subtly magnetized linear detail. The modeled dimensions of two components of this anomaly are 0.32 Ha and 0.2 Ha at depths of 32 m & 14 m for the deposits to the West and the East respectively. Garnet data for the Boya-02 occurrence reports a maximum Pmin value of 49.7 kbar (207 garnets). These data demonstrate the high diamond potential which assumes a conductive cratonic geotherm of 40 mWm<sup>2</sup>.展开更多
Highly evolved granite is an important sign of the mature continent crust and closely associated with deposits of rare metals.In this work,the authors undertake systematically zircon U-Pb ages and whole rock elemental...Highly evolved granite is an important sign of the mature continent crust and closely associated with deposits of rare metals.In this work,the authors undertake systematically zircon U-Pb ages and whole rock elemental data for highly evolved granitic intrusions from the Great Xing’an Range(GXR),NE China,to elucidate their discriminant criteria,spatial-temporal distribution,differentiation and geodynamic mecha-nism.Geochemical data of these highly evolved granites suggest that high w(SiO_(2))(>70%)and differentiation index(DI>88)could be quantified indicators,while strong Eu depletion,high TE_(1,3),lowΣREE and low Zr/Hf,Nb/Ta,K/Rb could only be qualitative indicators.Zircon U-Pb ages suggest that the highly evolved gran-ites in the GXR were mainly formed in Late Mesozoic,which can be divided into two major stages:Late Ju-rassic-early Early Cretaceous(162-136 Ma,peak at 138 Ma),and late Early Cretaceous(136-106 Ma,peak at 126 Ma).The highly evolved granites are mainly distributed in the central-southern GXR,and display a weakly trend of getting younger from northwest to southeast,meanwhile indicating the metallogenic potential of rare metals within the central GXR.The spatial-temporal distribution,combined with regional geological data,indicates the highly evolved Mesozoic granites in the GXR were emplaced in an extensional environ-ment,of which the Late Jurassic-early Early Cretaceous extension was related to the closure of the Mongol-Okhotsk Ocean and roll-back of the Paleo-Pacific Plate,while the late Early Cretaceous extension was mainly related to the roll-back of the Paleo-Pacific Plate.展开更多
The lithium potential in the Aïr massif is represented by mineral index of spodumene pegmatites and, lepidolite pegmatites. The mineral deposits of lithium occur in cluster or veins that cut the host rock or are ...The lithium potential in the Aïr massif is represented by mineral index of spodumene pegmatites and, lepidolite pegmatites. The mineral deposits of lithium occur in cluster or veins that cut the host rock or are located near the contact between the greenstone belt and granitic massif. The evidence of lithium is in the form of clusters or disseminated and stockwerk. Mineralogical characteristics show similarities between the Air Massif pegmatites and indicate the same homogenous source during the magma-generation process. The pegmatite rocks attracted the attention due to their wide exposure and composition, well appearance, and economically hosting of significant rare earth metals such as Sn and W. The mineralogical and petrographical investigations on the eight pegmatites rocks samples observed have a relative similarity, while a little difference in the shapes attributed to the ratio in the pegmatite rocks of the minerals. The occurrence of the kink band indicates the influence of the tectonic processes which affected the Aïr massif after the emplacement of late magmatic or post-magmatic pegmatites by injection into fractured rocks in the upper part of the crust. The Air Massif pegmatite has higher concentrations Li and of all trace elements except Hf and occasionally Zr, Ti, Sn and Mg of for the economic exploration.展开更多
Whether a Neoarchean basement existing in the Songnen massif is currently debated.Identification of Archean magmatism from the Songnen Massif is helpful to resolve this issue.Here,we report newly discovered Neoarchean...Whether a Neoarchean basement existing in the Songnen massif is currently debated.Identification of Archean magmatism from the Songnen Massif is helpful to resolve this issue.Here,we report newly discovered Neoarchean Shanquan pluton in the Western Songnen Massif.These Neoarchean Shanquan pluton are mainly composed of granites that are exposed near the town of Shanquan in Heilongjiang Province.LA-ICP-MS zircon U-Pb dating reveals that the sample 2015TW1 has an upper intercept age of 2801±69 Ma and a weighted mean age of 2708±18 Ma,while samples LJ27QY1 and LJ27QY2 have upper intercept ages of 2677±57 Ma and 2653±18 Ma,and weighted mean ages of 2649±10 Ma and 2653±15 Ma,respectively.This indicates that these granites were formed at~2.7 Ga.Most of the~2.7 Ga zircons have older TDM2 ages of 2762–3326 Ma with positiveεHf(t)values ranging from 0 to 6.4,while a few of the zircons have negativeεHf(t)values ranging from-8.1 to-11.5 and older TDM2 ages varying from 3158 to 3264 Ma.The zircon Hf isotopes indicate that Paleo-Mesoarchean crusts might once existed in the Songnen Massif,and the studied Neoarchean magmas were principally derived from partial melting of these Paleo-Mesoarchean ancient crust.Based on the geochronological spectrum of magmatic and detrital zircons,the Songnen,Erguna,Jiamusi,Bureya massifs may have a common basement prior to the Neoproterozoic and may even be linked with the Triam Craton.展开更多
Zircon U-Pb isotope dating and whole-rock geochemical analyses were undertaken for the rhyolite,rhyolitic lithic crystal tuff and dacitic tuff from the Manketouebo Formation in the Keyihe area,in order to constrain th...Zircon U-Pb isotope dating and whole-rock geochemical analyses were undertaken for the rhyolite,rhyolitic lithic crystal tuff and dacitic tuff from the Manketouebo Formation in the Keyihe area,in order to constrain their genesis and tectonic significance.Zircon LA-ICP-MS U-Pb data indicate that the rhyolite and rhyolitic lithic crystal tuff were formed during 137±5 Ma and 143±1 Ma,respectively.These volcanic rocks have high SiO2(70.03%–76.46%)and K2O+Na2O(8.10%–9.52%)contents,but low CaO(0.03%–0.95%)and MgO(0.07%–0.67%)contents,which belong to the peraluminous and high-K calc-alkaline rocks.They are enriched in light rare earth elements(REEs),and exhibit fractionation of light over heavy REEs,withδEu values of 0.37–0.83.The volcanic rocks are enriched in LILEs(e.g.,Rb,U and K)and depleted in HFSEs(e.g.,Nb,Ti,P and Ta).The chemical composition suggests that these volcanic rocks formed by partial melting of crust material.Combined with previous regional research results,the authors consider that the volcanic rocks of the Manketouebo Formation in the Keyihe area were formed under an extensional environment related to the closure of the Mongolia–Okhotsk Ocean.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41671011,41871019,41877292,41972212)Research Foundation of Chutian Scholars Program of Hubei Province(Grant No.8210403)Shanxi Key Research and Development program:Feng Cheng(Grant No.2021SF2-03).
文摘Plate subduction leads to complex exhumation processes on continents.The Huangling Massif lies at the northern margin of the South China Block.Whether the Huangling Massif was exhumed as a watershed of the middle reaches of the Paleo-Yangtze River during the Mesozoic remains under debate.We examined the exhumation history of the Huangling Massif based on six granite bedrock samples,using apatite fission track(AFT)and apatite and zircon(U-Th)/He(AHe and ZHe)thermochronology.These samples yielded ages of 157–132 Ma(ZHe),119–106 Ma(AFT),and 114–72 Ma(AHe),respectively.Thermal modeling revealed that three phases of rapid cooling occurred during the Late Jurassic–Early Cretaceous,late Early Cretaceous,and Late Cretaceous.These exhumation processes led to the high topographic relief responsible for the emergence of the Huangling Massif.The integrated of our new data with published sedimentological records suggests that the Huangling Massif might have been the watershed of the middle reaches of the Paleo-Yangtze River since the Cretaceous.At that time,the rivers flowed westward into the Sichuan Basin and eastward into the Jianghan Basin.The subduction of the Pacific Plate beneath the Asian continent in the Mesozoic deeply influenced the geomorphic evolution of the South China Block.
文摘The Boya-02 kimberlite was identified at depth by geophysical survey work (a single-probe AM survey in 1997 and a gravity survey in 2006) that De Beers DRC Exploration carried out around anomaly 193/172/0019. This anomaly located approximately 50 km southwest of the town of Mbuji-Mayi in the Kasaï-Oriental Province in the DRC should therefore be the subject of detailed exploration with the aim of better identifying and describing this kimberlite. Thus, through exploratory work and cross-checking of geophysical and geological data, the discovery of this Massif was made by drilling on the aeromagnetic anomaly 193/172/X298. Based on drilling, sampling and laboratory petrographic analysis reports, the Boya-02 kimberlite was classified among highly diluted re-sedimented volcaniclastic kimberlites (KVR), rich in olivine and incidentally in quartz and poor in juvenile substances. This kimberlite represents a deposit of very low economic interest following extremely high dilution. The Boya-02 kimberlite was modeled using ground magnetism data. It is a complex anomaly comprising 2 components with variable amplitude appearing on a subtly magnetized linear detail. The modeled dimensions of two components of this anomaly are 0.32 Ha and 0.2 Ha at depths of 32 m & 14 m for the deposits to the West and the East respectively. Garnet data for the Boya-02 occurrence reports a maximum Pmin value of 49.7 kbar (207 garnets). These data demonstrate the high diamond potential which assumes a conductive cratonic geotherm of 40 mWm<sup>2</sup>.
基金Supported by projects of the National Natural Science Foundation of China(Nos.92062216,41888101).
文摘Highly evolved granite is an important sign of the mature continent crust and closely associated with deposits of rare metals.In this work,the authors undertake systematically zircon U-Pb ages and whole rock elemental data for highly evolved granitic intrusions from the Great Xing’an Range(GXR),NE China,to elucidate their discriminant criteria,spatial-temporal distribution,differentiation and geodynamic mecha-nism.Geochemical data of these highly evolved granites suggest that high w(SiO_(2))(>70%)and differentiation index(DI>88)could be quantified indicators,while strong Eu depletion,high TE_(1,3),lowΣREE and low Zr/Hf,Nb/Ta,K/Rb could only be qualitative indicators.Zircon U-Pb ages suggest that the highly evolved gran-ites in the GXR were mainly formed in Late Mesozoic,which can be divided into two major stages:Late Ju-rassic-early Early Cretaceous(162-136 Ma,peak at 138 Ma),and late Early Cretaceous(136-106 Ma,peak at 126 Ma).The highly evolved granites are mainly distributed in the central-southern GXR,and display a weakly trend of getting younger from northwest to southeast,meanwhile indicating the metallogenic potential of rare metals within the central GXR.The spatial-temporal distribution,combined with regional geological data,indicates the highly evolved Mesozoic granites in the GXR were emplaced in an extensional environ-ment,of which the Late Jurassic-early Early Cretaceous extension was related to the closure of the Mongol-Okhotsk Ocean and roll-back of the Paleo-Pacific Plate,while the late Early Cretaceous extension was mainly related to the roll-back of the Paleo-Pacific Plate.
文摘The lithium potential in the Aïr massif is represented by mineral index of spodumene pegmatites and, lepidolite pegmatites. The mineral deposits of lithium occur in cluster or veins that cut the host rock or are located near the contact between the greenstone belt and granitic massif. The evidence of lithium is in the form of clusters or disseminated and stockwerk. Mineralogical characteristics show similarities between the Air Massif pegmatites and indicate the same homogenous source during the magma-generation process. The pegmatite rocks attracted the attention due to their wide exposure and composition, well appearance, and economically hosting of significant rare earth metals such as Sn and W. The mineralogical and petrographical investigations on the eight pegmatites rocks samples observed have a relative similarity, while a little difference in the shapes attributed to the ratio in the pegmatite rocks of the minerals. The occurrence of the kink band indicates the influence of the tectonic processes which affected the Aïr massif after the emplacement of late magmatic or post-magmatic pegmatites by injection into fractured rocks in the upper part of the crust. The Air Massif pegmatite has higher concentrations Li and of all trace elements except Hf and occasionally Zr, Ti, Sn and Mg of for the economic exploration.
基金co-supported by the National Key R&D Program of China(Grant No.42130305)China Geological Survey(Grant Nos.DD20221687,DD20230047,DD20160047)the NSFC project(Grant Nos.41802238,42102271)。
文摘Whether a Neoarchean basement existing in the Songnen massif is currently debated.Identification of Archean magmatism from the Songnen Massif is helpful to resolve this issue.Here,we report newly discovered Neoarchean Shanquan pluton in the Western Songnen Massif.These Neoarchean Shanquan pluton are mainly composed of granites that are exposed near the town of Shanquan in Heilongjiang Province.LA-ICP-MS zircon U-Pb dating reveals that the sample 2015TW1 has an upper intercept age of 2801±69 Ma and a weighted mean age of 2708±18 Ma,while samples LJ27QY1 and LJ27QY2 have upper intercept ages of 2677±57 Ma and 2653±18 Ma,and weighted mean ages of 2649±10 Ma and 2653±15 Ma,respectively.This indicates that these granites were formed at~2.7 Ga.Most of the~2.7 Ga zircons have older TDM2 ages of 2762–3326 Ma with positiveεHf(t)values ranging from 0 to 6.4,while a few of the zircons have negativeεHf(t)values ranging from-8.1 to-11.5 and older TDM2 ages varying from 3158 to 3264 Ma.The zircon Hf isotopes indicate that Paleo-Mesoarchean crusts might once existed in the Songnen Massif,and the studied Neoarchean magmas were principally derived from partial melting of these Paleo-Mesoarchean ancient crust.Based on the geochronological spectrum of magmatic and detrital zircons,the Songnen,Erguna,Jiamusi,Bureya massifs may have a common basement prior to the Neoproterozoic and may even be linked with the Triam Craton.
基金Supported by Project of National Natural Science Foundation of China(No.41872234)。
文摘Zircon U-Pb isotope dating and whole-rock geochemical analyses were undertaken for the rhyolite,rhyolitic lithic crystal tuff and dacitic tuff from the Manketouebo Formation in the Keyihe area,in order to constrain their genesis and tectonic significance.Zircon LA-ICP-MS U-Pb data indicate that the rhyolite and rhyolitic lithic crystal tuff were formed during 137±5 Ma and 143±1 Ma,respectively.These volcanic rocks have high SiO2(70.03%–76.46%)and K2O+Na2O(8.10%–9.52%)contents,but low CaO(0.03%–0.95%)and MgO(0.07%–0.67%)contents,which belong to the peraluminous and high-K calc-alkaline rocks.They are enriched in light rare earth elements(REEs),and exhibit fractionation of light over heavy REEs,withδEu values of 0.37–0.83.The volcanic rocks are enriched in LILEs(e.g.,Rb,U and K)and depleted in HFSEs(e.g.,Nb,Ti,P and Ta).The chemical composition suggests that these volcanic rocks formed by partial melting of crust material.Combined with previous regional research results,the authors consider that the volcanic rocks of the Manketouebo Formation in the Keyihe area were formed under an extensional environment related to the closure of the Mongolia–Okhotsk Ocean.
