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In Situ Rb-Sr Dates of Muscovite and Sulfur Isotope of Pyrite from the Yangshan Gold Deposit in Western Qinling,China
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作者 HUANG Yong QI Xianmao +10 位作者 WU Qingsong LI Jianzhong REN Minghua DUAN Liu’an XIONG Tao YANG Zhonghu ZHAO Yang CIREN Lamu WEI Wei DUAN Jilin YAN Mengmeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2023年第5期1475-1489,共15页
Located along the southern part of the West Qinling orogenic belt,the Yangshan gold deposit is one of the largest in China.The major gold ores of Yangshan are disseminated in metasedimentary host rocks with minor nati... Located along the southern part of the West Qinling orogenic belt,the Yangshan gold deposit is one of the largest in China.The major gold ores of Yangshan are disseminated in metasedimentary host rocks with minor native gold amounts in stibnite-gold quartz veins.Pyrite and arsenopyrite are the major Au-bearing minerals.Hydrothermal muscovite from gold-bearing quartz veins was dated using the in situ Rb-Sr method to determine the formation age of the Yangshan gold deposit.The Rb-Sr isochron date of the muscovite yielded 210.1±5.6 Ma(MSWD=1.2).This date is near the lower end of the period of the mineralized granitic dykes(210.49-213.10 Ma).Two stages of gold enriching process are recognized in the gold-bearing pyrite:the first is incorporated with the Co,Cu,As,Ni enrichment;and the second is accompanied by Bi,Co,Ni,Pb,Cu,Sb concentration.The in-situ sulfur isotopic values of pyrites show a restrictedΔ34s range of-1.43‰to 2.86‰with a mean value of 0.43‰.Trace-element mapping and in-situ sulfur isotopic analysis of pyrite suggest that the sulfur deposits are likely derived from a magmatic source and likely assimilated by sulfur from the sedimentary bedrock.Thus,magmatism plays a critical role in the formation of the Yangshan gold deposit. 展开更多
关键词 rb-sr dating trace-element mapping sulfur isotope gold deposit Yangshan Qinling orogenic belt
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Geochemistry of Ore Fluids and Rb-Sr Isotopic Dating for the Wulong Gold Deposit in Liaoning, China 被引量:12
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作者 WEIJunhao QIUXiaoping +1 位作者 GUODazhao TANWenjuan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第6期1267-1274,共8页
On the basis of detailed geological studies of the Wulong gold deposit, three metallogenic stages can be identified. With quartz fluid inclusions as an object of study, the authors investigated phase characteristics, ... On the basis of detailed geological studies of the Wulong gold deposit, three metallogenic stages can be identified. With quartz fluid inclusions as an object of study, the authors investigated phase characteristics, compositional variations, temperature and pressure changes, fluid evolution, Pb isotope tracing and Rb-Sr isotopic dating of fluid inclusions entrapped in the above three metallogenic stages. The results show that Na+ is decreased obviously with metallogenic evolution, while K+ and other cations and gas compositions (H2, CO, CH4 and CO2) are increased slightly, and that the temperature and salinity vary in a pulsating manner along with the metallogenic evolution. Inverse calculation of hydrogen and oxygen isotopes indicate that at the first metallogenic stage the fluids were magmatic water, at the second stage they were dominated by magmatic water with a minor amount of meteoric water involved, and at the third stage, i.e., the final stage of metallogenesis, the fluids were composed completely of meteoric water. Its Pb isotopic composition implicates that the ore lead has some affinities with the lead in the Sanguliu granite, but the linear array of the ore-lead isotopic data reflects a mixing source of two end members. It can be deduced that the ore-forming materials and magma were both derived mainly from the same magma source region at depths. The Rb-Sr isotopic ages of the fluid inclusions are 112.2±3.2 Ma, indicating that the Wulong gold deposit was formed during the Yanshanian period. 展开更多
关键词 metallogenic evolution temperature and pressure conditions ISOTOPES rb-sr dating Wulong gold deposit
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Rb-Sr Dating of Pyrite and Quartz Fluid Inclusions and Origin of Ore-forming Materials of the Jinshan Gold Deposit, Northeast Jiangxi Province, South China 被引量:2
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作者 MAO Guangzhou HUA Renmin +1 位作者 LONG Guangming LU Huijuan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2013年第6期1658-1667,共10页
The Jinshan gold deposit is located in the Northeast Jiangxi province,South China,which related to the ductile shear zone.It contains two ore types,i.e.the alteration-type ore and the goldbearing quartz vein ore.Rb-Sr... The Jinshan gold deposit is located in the Northeast Jiangxi province,South China,which related to the ductile shear zone.It contains two ore types,i.e.the alteration-type ore and the goldbearing quartz vein ore.Rb-Sr age dating is applied to both gold-bearing pyrite in the alteration-type ore and fluid inclusion in the gold-bearing quartz vein to make clear the time of the gold mineralization of the Jinshan deposit.Analytical results of this study yielded that the age of the alteration-type ore bodies is about 838±110Ma,with an initial 87Sr/86Sr value of 0.7045±0.0020.However,the age of the gold-bearing quartz vein-type ore is about 379±49Ma,and the initial 87Sr/86Sr is 0.7138±0.0011.Based on the age data from this work and many previous studies,the authors consider that the Jinshan gold deposit is a product of multi-staged mineralization,which may include the Jinninian,Caledonian,Hercynian,and Yanshanian Periods.Among them,the Jinninian Period and the Hercynian Period might be the two most important ore-forming periods for Jinshan deposit.The Jinninian Period is the main stage for the formation of alteration-type ore bodies,while the Hercynian Period is the major time for ore bodies of gold-bearing quartz vein type.The initial values of the 87Sr/86Sr from this study,as well as the previous isotope and trace element studies,indicate that the ore-forming materials mainly derived from the metamorphic wall rocks,and the ore-forming fluids mainly originated from the deep metamorphic water. 展开更多
关键词 Gold deposit mineralization time quartz fluid inclusion PYRITE rb-sr dating Origin of the ore-forming materials Jinshan Jiangxi province
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Dating Model of Illite Grain Rb-Sr Isochron and Its Application to Precambrian Stratigraphy
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作者 Li Yunjun Institute of Geology, Academia Sinica, Beijing Jia Zhongpeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1989年第1期93-102,共10页
This paper discusses the Rb-Sr geochemical behaviour of illites in the sedimentary process, and points out that illites of the lmd and lm types could reach Sr-isotopic equilibrium with its environmental medium during ... This paper discusses the Rb-Sr geochemical behaviour of illites in the sedimentary process, and points out that illites of the lmd and lm types could reach Sr-isotopic equilibrium with its environmental medium during the sedimentary process and initial stage of diagenesis, and illite grains of different sizes have various Rb contents. A new dating method for sedimentary rocks----a dating model of illite grain Rb-Sr isochron----is established, in consideration of the geochemical process of Sr-isotopic homogenization and differentiation in the course of their formation and evolution. In addition, the paper concerns the application of the dating model to the Precambrian unmetamorphosed sedimentary rocks in western Henan Province, which gives satisfactory results coincident with the geological facts. 展开更多
关键词 dating Model of Illite Grain rb-sr Isochron and Its Application to Precambrian Stratigraphy Sr Rb
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Monazite U-Th-Pb and sericite Rb-Sr dating of the Xiajiadian black shale-hosted gold deposit in the Qinling orogen,central China:Implications for regional gold metallogeny
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作者 Xueling YU Jianwei LI +3 位作者 Xiaoye JIN Shaorui ZHAO Chongguo HE Yunlong ZHU 《Science China Earth Sciences》 SCIE EI CAS CSCD 2024年第8期2478-2494,共17页
The Qinling orogen in central China contains several black shale-hosted gold deposits,but the age of their formation and a possible relation between gold mineralization and regional tectonism remain undetermined.Here ... The Qinling orogen in central China contains several black shale-hosted gold deposits,but the age of their formation and a possible relation between gold mineralization and regional tectonism remain undetermined.Here we present results of in situ monazite U-Th-Pb dating and sericite Rb-Sr dating of the Xiajiadian black shale-hosted gold deposit to provide tight constraints on the time of gold deposition and information on the tectonic setting under which the deposit formed.The Xiajiadian gold deposit is mainly hosted in black shales of the Lower Cambrian Shuigoukou formation,with minor ores contained in sandy conglomerate of the Lower Devonian Xichahe formation.Gold ores in the black shales have been intensively oxidized and consist mainly of hematite,goethite,gypsum,quartz,calcite,native gold,and unrecognized iron oxides.However,gold ores in the sandy conglomerate are free of oxidation and thus provide an opportunity to date the formation of the Xiajiadian gold deposit.The ores consist of pyrite,marcasite,sericite,and quartz,which are associated with a variety of accessory minerals,including monazite,apatite,and titanite.Gold is mainly present as structure-bound ions or nanoparticles in pyrite and marcasite,but minor native gold grains also occur as inclusions in pyrite.Monazite is well developed in the ores,and has close textural association with Au-bearing pyrite and marcasite.Most monazite grains have zoned textures consisting of a core area(Mnz1)and an overgrowth zone(Mnz2).Mnz1 contains 4.8–13 wt.%ThO_(2)and shows large variations in HREE and prominent negative Eu anomalies in the chondrite-normalized REE patterns.It yields common lead-corrected^(208)Pb/^(232)Th dates ranging from 910±10 to416±4 Ma(2σ).These dates are interpreted in terms of a detrital origin for monazite in the core area.Mnz2 has much lower ThO_(2)contents of 0.8–1.7 wt.%and shows weak negative Eu anomalies in the chondrite-normalized REE patterns.It yields common lead-corrected^(208)Pb/^(232)Th dates of 229–209 Ma(2σ)with a weighted mean of 217.6±3.0 Ma(2σ),which is considered as the time of Mnz2 crystallization.Sericite in gold ores and associated alteration zones has close relations to Au-bearing pyrite and marcasite,and yields a well-defined Rb-Sr isochron age of 222.2±3.3 Ma(2σ).The sericite Rb-Sr age is indistinguishable within analytical errors from the weighted mean Th-Pb age of Mnz2.The age data presented here indicate that the Xiajiadian gold deposit formed at ca.220 Ma in the Late Triassic(Norian).We therefore suggest that gold mineralization at Xiajiadian occurred during the transitional stage from oceanic subduction to continental collision that led to the formation of the Qinling orogen.During this stage,metamorphic devolatization of the underlying Early Paleozoic to Proterozoic carbonaceous sequences likely supplied ore fluids from which the Xiajiadian gold deposit formed. 展开更多
关键词 Monazite U-Th-Pb dating Sericite rb-sr dating Late Triassic(Norian) Orogenic gold deposit Xiajiadian
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^40Ar/^39Ar and Rb-Sr Ages of the Tiegelongnan Porphyry Cu-(Au)Deposit in the Bangong Co-Nujiang Metallogenic Belt of Tibet,China:Implication for Generation of Super-Large Deposit 被引量:36
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作者 LIN Bin CHEN Yuchuan +6 位作者 TANG Juxing WANG Qin SONG Yang YANG Chao WANG Wenlei HE Wen ZHANG Lejun 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第2期602-616,共15页
The Tiegelongnan deposit is a newly discovered super-large porphyry-epithermal Cu-(Au) deposit in the western part of the Bangong Co-Nujiang metallogenic belt, Tibet(China). Field geology and geochronology indicat... The Tiegelongnan deposit is a newly discovered super-large porphyry-epithermal Cu-(Au) deposit in the western part of the Bangong Co-Nujiang metallogenic belt, Tibet(China). Field geology and geochronology indicate that the porphyry mineralization was closely related to the Early Cretaceous intermediate-felsic intrusions(ca. 123–120 Ma). Various epithermal ore and gangue mineral types were discovered in the middle-shallow part of the orebody, indicating the presence of epithermal mineralization at Tiegelongnan. Potassic, propylitic, phyllic and advanced argillic alteration zones were identified. 40Ar/39Ar dating of hydrothermal biotite(potassic zone), sericite(phyllic zone), and alunite(advanced argillic zone) in/around the ore-bearing granodiorite porphyry yielded 121.1±0.6 Ma(1σ), 120.8±0.7 Ma(1σ) and 117.9±1.6 Ma(1σ), respectively. Five hydrothermal mineralization stages were identified, of which the Stage IV pyrite was Rb-Sr dated to be 117.5±1.8 Ma(2σ), representing the end of epithermal mineralization. Field geology and geochronology suggest that both the epithermal and porphyry mineralization belong to the same magmatic-hydrothermal system. The Tiegelongnan super-large Cu-(Au) deposit may have undergone a prolonged magmatichydrothermal evolution, with the major mineralization event occurring at ca.120–117Ma. 展开更多
关键词 40Ar/39Ar and rb-sr dating Tiegelongnan Cu-(Au) deposit Bangong Co-Nujiang metallogenic belt TIBET Proto-Tethys
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Timing of the formation of the Baiyinnuo'er skarn Zn–Pb deposit,NE China:evidence from sulfide Rb–Sr dating
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作者 Yixin Li Qihai Shu +5 位作者 Xudong Niu Fan Yu Qingwen Zeng Liangmin Wei Yang Xiao Xianglin Dai 《Acta Geochimica》 EI CAS CSCD 2022年第2期185-196,共12页
The Baiyinnuo’er deposit in northern China is located in the south section of the Great Xing’an Range,and it is the largest skarn Zn–Pb deposit in the region.Skarn and Zn–Pb orebodies mainly occur between the diff... The Baiyinnuo’er deposit in northern China is located in the south section of the Great Xing’an Range,and it is the largest skarn Zn–Pb deposit in the region.Skarn and Zn–Pb orebodies mainly occur between the different units of the Permian Huanggangliang Formation,or within the contact zone between the intrusive rocks and the marble.Although Baiyinnuo’er has been well investigated previously,the timing of the Zn–Pb mineralization is still controversial,largely due to the lack of appropriate ore or alteration minerals that could be directly used for isotopic dating.In this study,we report the results of Rb–Sr isotopic analysis for sphalerite and pyrite samples from the Baiyinnuo’er orebodies,which yielded two isochron ages of 137.4±3.4 and 140.0±7.8 Ma,respectively,constraining the Zn–Pb mineralization time of the deposit as the Early Cretaceous.The data are also consistent with the age of the granitoids in the mining area,indicating a potential genetic relationship between the Early Cretaceous magmatism and mineralization.Many other intrusion-related hydrothermal deposits(including the two typical skarns,Huanggang and Haobugao)in the southern Great Xing’an Range also share similar mineralization ages(i.e.,140–130 Ma).Together,these data suggest an Early Cretaceous mineralization event in this region,and this largescale mineralization could be related to the regional tectonic regime transition from compression to extension as a result of the rollback of the subducted Paleo-Pacific plate.The initial87 Sr/86 Sr ratios of the sphalerite and pyrite samples are 0.70569 and 0.70616,respectively,implying that the ore-forming material could have a significant contribution from the mantle components.The current study shows that sulfide Rb–Sr dating could be used in deciphering the timing of skarn deposit formation. 展开更多
关键词 rb-sr dating Sphalerite and pyrite Skarn Zn-Pb deposit Baiyinnuo’er Southern Great Xing’an Range
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In situ Rb-Sr dating of mica by LA-ICP-MS/MS 被引量:2
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作者 Chao HUANG Hao WANG +7 位作者 Wenbei SHI Jinfeng SUN Fangyang HU Lei XU Yueheng YANG Shitou WU Liewen XIE Jinhui YANG 《Science China Earth Sciences》 SCIE EI CAS CSCD 2023年第11期2603-2621,共19页
Mica exhibits a relatively high Rb/Sr ratio and possesses a closure temperature for the Rb-Sr isotope system that is higher than the ore-forming temperature range of low-to medium-temperature deposits.Consequently,uti... Mica exhibits a relatively high Rb/Sr ratio and possesses a closure temperature for the Rb-Sr isotope system that is higher than the ore-forming temperature range of low-to medium-temperature deposits.Consequently,utilizing the laser ablation(LA)technique for in situ Rb-Sr dating in mica constitutes a significant methodology for resolving the mineralization chronology of low-to medium-temperature hydrothermal ore deposits.In this study,we employed a combination of a triple quadrupole inductively coupled plasma mass spectrometer(ICP-MS/MS)and 193 nm LA system with SF_6as the reaction gas to achieve interference removal of~(87)Rb~+on~(87)Sr~+.We then developed an in situ Rb-Sr dating method for mica.In addition,an investigation was conducted to identify the factors that could influence the analytical accuracy of the method.Subsequently,we applied the developed method to carry out in situ Rb-Sr dating for the ZBH-25 biotite,a national primary reference material(GBW04439)for K-Ar dating,and yielded a younger age(ca.12%,relative standard deviation,RSD)than the reference K-Ar age when using NIST SRM 610 as the reference material for external calibration.This finding indicated that in the process of determining Rb-Sr ages for mica by LA-ICP-MS/MS,there are significant matrix effects between the NIST SRM 610 and the mica samples,resulting in inaccurate Rb-Sr ages.In response to this issue,a two-step calibration method is proposed here.Based on external calibration using NIST SRM 610,ZBH-25 biotite is employed as a second external reference material to perform a second calibration of the sample data to correct the matrix effect between the glass standards and the natural mica samples,thereby improving the accuracy of Rb-Sr dating by LA-ICP-MS/MS.Using the proposed method,in situ Rb-Sr dating by LA-ICP-MS/MS was performed on mica samples from monzonite exposed in Mt.Dromedary,New South Wales,Australia,porphyritic granodiorite in Fangshan pluton and albionite granite in the Gyirong area of Tibet.The obtained Rb-Sr age results show agreement with the recommended values within the analytical uncertainty,which serves to validate the accuracy and effectiveness of the proposed method. 展开更多
关键词 MICA In situ analysis by laser ablation rb-sr dating Triple quadrupole mass spectrometer Matrix effect
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Early Paleozoic Magmatism and Gold Mineralization in the Northern Altun, NW China 被引量:4
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作者 CHENXuanhua WANGXiaofeng +6 位作者 GeorgeGEHRELS YANGYi QINHong CHENZhengle YANGFeng CHENBailin LIXuezhi 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第2期515-523,共9页
This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, includ... This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, including zircon U-Pb ages, Rb-Sr isochron age and 40Ar-39Ar dating and MDD modeling data. The main granitic magmatism age in this area is attained from the ID TIMS U-Pb geochronology of zircons from the Kuoshibulak granite, the biggest granite in the northern Altun area, which gives a concordant age of 443±5 Ma in the Late Ordovician. Zircon ID TIMS U-Pb geochronology of the West Dapinggou biotite granite west of the Dapinggou gold deposit gives concordant ages around 485±10 Ma, representing the early stage of Ordovician magmatism. The Rb-Sr isochron age (487±21 Ma) of 6 quartz inclusion samples from quartz veins in this gold deposit is very close to that of the West Dapinggou granite. MDD modeling of step heating 40Ar-39Ar data of K-feldspar from the same West Dapinggou biotite granite gives a rapid cooling history from 300℃ to 150℃ during 200-185 Ma. According to the age data and the geological setting of this area, we conclude that the Dapinggou gold deposit was formed at the early stage of the Early Paleozoic granitic magmatism in northern Altun, and exhumed in the Early Jurassic due to the normal faulting of the Lapeiquan detachment. The Early Paleozoic magmatism may provide heat source and produce geological fluids, which are very important for gold mineralization. Exhumation in the Mesozoic caused the uplift of the deposit towards the ground surface. 展开更多
关键词 granite zircon U-Pb chronology gold deposit rb-sr chronology EXHUMATION 40Ar-39Ar dating and MDD modeling northern Altun
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CHARACTERISTICS OF Nd AND Sr ISOTOPES AND TRACE ELEMENTS FOR LATE CRETAEOUS VOLCANIC ROCKS IN KING GEORGE ISLAND, ANTARCTICA: IMPLICATIONS FOR SOURCE OF THE VOLCANICS FROM DEPLETED MANTLE
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作者 王银喜 沈炎彬 杨杰东 《Chinese Journal of Polar Science》 1993年第1期12-25,共14页
Rb -Sr isotopic isochron dating of the volcanic rock samples from the Upper Cretaceous Half Three Point Formation on the King George Island is 71. 33±0. 3 Ma. Correlative study of εND(T)-147Sm/144Nd, 143Nd/144Nd... Rb -Sr isotopic isochron dating of the volcanic rock samples from the Upper Cretaceous Half Three Point Formation on the King George Island is 71. 33±0. 3 Ma. Correlative study of εND(T)-147Sm/144Nd, 143Nd/144Nd-87Sr/86Sr, 87Sr/86Sr-Sr and 87Sr/86Sr-K2O/(K2O+Na2O) indicated that the volcanic rocks were chiefly derived from the depleted mantle source and generally were not mixed crust materials. Of the samples 6 were given the mean Sm -Nd model age (TDM) of 443. 3±20. 6 Ma possibly indicating the age of chemical variation event in the magma source of the study area. Features of the trace elements indicated that the rocks from the Half Three Point Formation are of typical calc-alkaline volcanic suite and similar to those from the Tertiary volcanic rocks of the Fildes Peninsula, being the same products of the island-arc volcanic activity. 展开更多
关键词 Late Cretaceous rb-sr dating Nd-Sr isotopes trace elements petrgenesis
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Nd isotopic disequilibrium between minerals and Rb-Sr age of the secondary phengite in eclogite from the Yangkou area,Qingdao,eastern China 被引量:4
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作者 LI Shuguang SUN Weidong +1 位作者 ZHANG Zongqing LI Qiuli 《Chinese Science Bulletin》 SCIE EI CAS 2001年第3期252-255,共4页
There are two generations of white micas in retrograded coesite-bearing eclogite from the Yangkou area near Qingdao, eastern China. The secondary phengite developed along the folliations in eclogite is the majority of... There are two generations of white micas in retrograded coesite-bearing eclogite from the Yangkou area near Qingdao, eastern China. The secondary phengite developed along the folliations in eclogite is the majority of the white micas. Nd and Sr isotopic disequilibriums between garnet and retrograded omphacite as well as secondary phengite have been observed. Consequently, the Rb-Sr ages ((193±4) Ma-(195±4) Ma) given by the tie lines of the secondary phengite + garnet or whole rock may predate the formation time of the phengite. The Rb-Sr age of (183±4) Ma given by the secondary phengite + retrograde omphacite is much closer to the formation time of the phengite indicating the retrograde age of eclogite instead of a cooling age of eclogite at 500℃. 展开更多
关键词 ECLOGITE ND ISOTOPIC disequilibrium rb-sr dating Su-Lu UHPM belt.
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Dating and Nd, Sr, O Isotope Studies of the Chaganhundi Granite 被引量:2
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作者 周有勤 王银喜 《Chinese Science Bulletin》 SCIE EI CAS 1993年第19期1646-1650,共5页
The crust in northern Xinjiang intensely moved about during the Middle Hercynian, which formed a large area of granitoid. In the south of Alataw Mountain, granitic bodies such as Kongwusayi, Wulasitan, Zuluhong, Kazib... The crust in northern Xinjiang intensely moved about during the Middle Hercynian, which formed a large area of granitoid. In the south of Alataw Mountain, granitic bodies such as Kongwusayi, Wulasitan, Zuluhong, Kazibieke and Chaganhundi are distributed along the Bole W-Sn mineralization belt from east to west, of which the Zuluhong, Kazibieke and Chaganhundi granitic bodies in the west sector are directly related to W-Sn mineralizations of quartz vein type, greisen type and chlorite type in this area. 展开更多
关键词 GRANITE rb-sr dating ND SR O isotopes petrogenesis.
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Genesis of Makeng-type Fe-polymetallic deposits in SE China:New constraints by geochronological and isotopic data from the Dapai–Makeng metallogenic system
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作者 Absai Vatuva Xiaolong He +6 位作者 Xinming Zhang Da Zhang Haibin Feng Yuan Yuan Sen Wang Jinjun Yi Yongjun Di 《Geoscience Frontiers》 SCIE CAS CSCD 2023年第5期189-212,共24页
The southwestern Fujian depression belt(SFDB)is an economically important Mesozoic Fe metallogenic belt in South China and is renowned for its Makeng-type Fe deposits,in which stratified skarn Fe orebodies generally o... The southwestern Fujian depression belt(SFDB)is an economically important Mesozoic Fe metallogenic belt in South China and is renowned for its Makeng-type Fe deposits,in which stratified skarn Fe orebodies generally occur in or near the contact zone between late Paleozoic carbonate sequences and Mesozoic granites.However,the genesis and geodynamic setting of these deposits remain unclear because the characteristics of the widely distributed Pb–Zn–Cu and Mo orebodies in these deposits and the temporal,spatial,and genetic relationships between magmatism and mineralization are poorly defined.The Dapai Fe polymetallic deposit in the SFDB is a typical example of Makeng-type Fe deposits but also has regional significance,whereby the stratified skarn Fe orebodies have overprinted the stratabound Pb–Zn–Cu mineralization followed by final fissure-filling by vein-disseminated Mo mineralization.A detailed geological investigation suggests that episodic magmatic–hydrothermal events were involved in the formation process of the Dapai Fe polymetallic deposit.Pyrite and sphalerite from the Pb–Zn–Cu orebodies yield an Rb–Sr isochron age of 175.5±3.3 Ma,which is regarded as the timing of Pb–Zn–Cu mineralization.Zircon grains from Fe-mineralized granodiorite porphyry and Mo-mineralized monzogranite yield weighted-mean 206Pb/238U ages of 146.3±0.9 Ma and 131.7±0.4 Ma,interpreted as the timings of Fe and Mo mineralization,respectively.Six zircons from granodiorite also yield a 206Pb/238U model age cluster of184 Ma,which coincides reasonably with the timing of Pb–Zn–Cu mineralization and implies the existence of an unidentified ore-related intrusion in the Dapai deposit.Five further zircons from the porphyritic granodiorite yield an age cluster of-150 Ma,consistent with the timing of Fe mineralization.Galena,pyrite,and sphalerite from the Dapai and Makeng deposits have similar S–Pb isotopic compositions and suggest a magmatic source.Combining our results with published isotopic data for the SFDB,we suggest that the Pb–Zn–Cu mineralization in this area was derived from crustal magmas that mixed with mantle-derived magma prior to emplacement.The d56Fe and d57Fe values of magnetite from Dapai and Makeng are both slightly lower than those of the orerelated granites,suggesting that Fe in the initial fluid in both deposits was derived mainly from coeval granitic rocks.The Fe isotopic variation between intrusions and skarn Fe orebodies is interpreted as resulting from mass fractionation that occurred during fluid exsolution from melt.Contents of Re in molybdenite from published data for the SFDB indicate crust–mantle mixed sources of Mo and Re.The Makeng-type Fe polymetallic deposits formed as a result of three magmatic–hydrothermal episodes,generating Pb–Zn–Cu mineralization at 185–160 Ma,Fe–Mo mineralization at 150–140 Ma,and Mo–Fe mineralization at 135–130 Ma.The different metal associations formed during multiple stages of magmatism caused by ongoing subduction and rollback and/or retreat of the paleo-Pacific Plate. 展开更多
关键词 Southwestern Fujian Depression Belt Makeng-type Fe polymetallic deposit Sulfide rb-sr dating Zircon U-Pb dating S-Pb-Fe isotopes Geodynamic setting
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Timanide(Ediacaran–Early Cambrian) Metamorphism at the Transition from Eclogite to Amphibolite Facies in the Beloretsk Complex,SW-Urals,Russia 被引量:1
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作者 Arne P.Willner Michael Gopon +2 位作者 Johannes Glodny Victor N.Puchkov Hans-Peter Schertl 《Journal of Earth Science》 SCIE CAS CSCD 2019年第6期1144-1165,共22页
The Beloretsk Metamorphic Complex in the SW Urals formed at a convergent eastern margin of Baltica during the Neoproterozoic–Early Cambrian Timanide orogeny.It comprises three major units with lenses of facies-critic... The Beloretsk Metamorphic Complex in the SW Urals formed at a convergent eastern margin of Baltica during the Neoproterozoic–Early Cambrian Timanide orogeny.It comprises three major units with lenses of facies-critical metabasites within metasedimentary rocks:A lowermost eclogite unit,an intermediate garnet amphibolite unit and an upper amphibolite-greenschist unit.Pressure(P)-temperature(T)-paths of four rocks from the two lowermost units were determined mainly by PT pseudosection techniques showing similar clockwise loops at different peak metamorphic,watersaturated conditions:A phengite-bearing eclogite shows peak PT conditions of 16.5–18.5 kbar/525–550℃(stage I)followed by stage II at 11.5–13.0 kbar/585–615℃.A garnet amphibolite from the intermediate unit yields lower peak conditions of 11.7–14.5 kbar/480–510℃(stage I)followed by stage II at 9.5–11.0 kbar/535–560℃.However,a granite gneiss in the eclogite unit shows similar maximum pressures as the eclogite,but higher temperatures at 15.6–16.2 kbar/660–675℃,whereas a garnet micaschist contains comparable high pressure relicts,but underwent an advanced midcrustal reequilibration at 7.5–9.0 kbar/555–610℃.We dated the eclogite by a 7-point Rb/Sr mineral isochron(phengite,omphacite,apatite)at 532.2±9.1 Ma interpreted as age of crystallisation of the eclogitic peak PT assemblage.This age is the youngest compared to the known Timanide metamorphic and magmatic ages. 展开更多
关键词 URALS ECLOGITE high pressure METAMORPHISM Timanide OROGENY rb-sr dating PT PSEUDOSECTIONS PT-path
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