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Discussion on Rb-Sr Isochron Ages of Granitoids in the Hengduan Mountains
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作者 Zhang Yuquan Zhu Bingquan Xie Yingwen Institute of Geochemistry, Academia Sinica, Guiyang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1990年第2期223-232,共10页
Based on the Rb-Sr isotopic study of the granitoids in the Hengduan Mountains, the classification andgeologic significance of whole-rock Rb-Sr isochrons as well as the factors influencing homogenization of theisotopic... Based on the Rb-Sr isotopic study of the granitoids in the Hengduan Mountains, the classification andgeologic significance of whole-rock Rb-Sr isochrons as well as the factors influencing homogenization of theisotopic systems are discussed. Usually. there is no good linear correlation of isochrons for diorites andalkali-rich intrusive rocks (including alkaline rock and alkalic granite). But by means of the external isochron ofmonominerals from the rocks. isochrons with good linear correlation as well as ages and Sr initial ratios with ahigh confidence can be obtained. In order to obtain a satisfactory isochron, the discriminant parameters shouldbe calculated from the Rb/Sr ratios and estimated ages of samples. Only those that meet the requirements canbe used as the Rb-Sr isochrons. The quality of an isochron should be judged from three factors, i.e. correlationcoefficient. MSWD and homogenization degree. 展开更多
关键词 RB SR Discussion on rb-sr isochron Ages of Granitoids in the Hengduan Mountains
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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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Rb-Sr isochron ages and significance of bimodal volcanic association in Baimianshi uranium ore-field, South China
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作者 CHEN Peirong~1, WANG Yinxi~2, NI Qisheng~1, KONG Xinggong~2 and ZHANG Bangtong~2 1. State Key Laboratory of Mineral Deposits, Department of Earth Sciences, Nanjing University, Nanjing 210093, China 2. Center of Modern Analysis, Nanjing University, Nanjing 210093, China 《Chinese Science Bulletin》 SCIE EI CAS 1999年第S2期3-4,共2页
1 Geologic background THE volcanic U-deposits are generally associated with felsic to intermediate volcanic rock and their sedimentary derivatives. However, uranium mineralization has been found to be spatially associ... 1 Geologic background THE volcanic U-deposits are generally associated with felsic to intermediate volcanic rock and their sedimentary derivatives. However, uranium mineralization has been found to be spatially associated with thebasalt of bimodal volcanic associations in Baimianshi uranium ore field. Baimianshi uranium ore-field islocated in Baimianshi volcanic-sedimentary basin of south Jiangxi Province. The cover rocks of the basinconsist of a suite of bimodal volcanic-sedimentary sequences. Its basement rocks are two-mica granites ofBaimianshi rock body. The basalt of cover rocks is interbedded with arkoses in lower sequence, and rhyolite or rhyolitic tuff in upper sequence. Uranium minerals mainly occur as disseminations in the 展开更多
关键词 rb-sr isochron AGES BIMODAL VOLCANIC rocks uranium ore-field south China.
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白云鄂博矿床云母地球化学特征及原位Rb-Sr定年:对稀土-铌成矿作用的指示
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作者 姚璐航 李扬 +4 位作者 张文 杨澜 余艳 杨波 李献华 《岩石学报》 北大核心 2025年第4期1149-1169,共21页
白云鄂博矿床是世界级的稀土矿床,并蕴含有丰富的铁、氟和铌等资源。云母是该矿床中常见的矿物之一,常与矿石和脉石矿物共生。基于详细的矿床地质和岩相学研究,本文选取了白云鄂博矿床中含云母的代表性矿石类型,包括云母型矿石、萤石条... 白云鄂博矿床是世界级的稀土矿床,并蕴含有丰富的铁、氟和铌等资源。云母是该矿床中常见的矿物之一,常与矿石和脉石矿物共生。基于详细的矿床地质和岩相学研究,本文选取了白云鄂博矿床中含云母的代表性矿石类型,包括云母型矿石、萤石条带状矿石、白云石型矿石和霓石型矿石,对其开展了云母原位Rb-Sr定年及地球化学分析,以揭示碳酸岩岩浆-热液演化过程及其对稀土-铌成矿作用的控制。研究结果表明,四类矿石中的云母均为热液成因,结晶温度约为230~480℃。萤石条带状矿石、白云石型矿石和霓石型矿石中的云母主要为富镁金云母,其中,萤石条带状矿石和霓石型矿石中的金云母Rb-Sr反等时线年龄分别为410±14Ma(n=20)和399±12Ma(n=15),而白云石型矿石中的金云母Rb-Sr同位素体系可能被扰动;云母型矿石以镁质黑云母为主,黑云母Rb-Sr反等时线年龄为287±16Ma(n=20)。本文研究揭示,在早古生代,贫稀土的云母主要以脉石矿物的形式从热液流体中结晶,促进了残余流体中稀土含量的升高和之后的矿化;而在二叠纪,部分云母的Rb-Sr体系被矿区大规模的花岗质岩浆活动重置,记录了对早期矿化的改造,可能与高品位的铌矿化相关。 展开更多
关键词 白云鄂博矿床 云母 地球化学 rb-sr同位素定年
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北冰洋楚科奇边缘地北风深渊中碱性火山岩锆石U-Pb年龄与白云母原位Rb-Sr等时线年龄及其大地构造意义
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作者 朱亚博 陈华勇 +1 位作者 董彦辉 糜梅 《大地构造与成矿学》 北大核心 2025年第1期206-217,I0014-I0017,共16页
楚科奇边缘地位于北冰洋美亚海盆的核心位置,作为水下高地,其从阿拉斯加-楚科奇大陆架延伸至美亚海盆中。楚科奇边缘地的研究对于重建北极地区的板块构造演化过程非常关键。目前关于其地壳性质、起源和演化过程仍不清晰。本次研究对楚... 楚科奇边缘地位于北冰洋美亚海盆的核心位置,作为水下高地,其从阿拉斯加-楚科奇大陆架延伸至美亚海盆中。楚科奇边缘地的研究对于重建北极地区的板块构造演化过程非常关键。目前关于其地壳性质、起源和演化过程仍不清晰。本次研究对楚科奇边缘地北风深渊平原斜坡上获取的碱性火山岩样品进行了详细分析,使用矿物自动定量分析(TIMA)方法研究了其岩性特征,运用LA-ICP-MS测定了样品中119颗锆石的U-Pb同位素年龄,同时使用LA-ICP-MS技术对样品薄片中的微晶白云母进行了原位Rb-Sr等时线年龄测定。结果表明, 119颗锆石的年龄可划分为94~636 Ma、929~1369 Ma、1655~2040 Ma和2439~2735 Ma四组。结合前人对在楚科奇边缘地获取的变质岩锆石U-Pb年龄和加拿大北极地区碎屑锆石年龄特征发现,第二组、第三组和第四组捕获锆石可能来源于加拿大北极群岛基底。第一组年轻锆石Th/U值较高,为典型的岩浆锆石,其中最年轻的6颗锆石的加权平均年龄为100.9±1.2 Ma,可能代表该碱性火山岩的形成年龄。白云母原位Rb-Sr等时线年龄为72±17 Ma,稍晚于样品中最年轻锆石年龄,能够与镜下白云母多呈脉状交代碱性岩的现象相对应,因此,样品中脉状白云母很可能是后期海底构造-热液活动的产物。本次研究所获得的锆石与白云母年龄从地质年代的角度证实了美亚海盆是由阿拉斯加-楚科奇微板块在早白垩世期间从北美板块边缘分离形成的,并且经历了后期的海底构造-热液叠加作用。 展开更多
关键词 北冰洋美亚海盆 楚科奇边缘地 锆石U-Pb定年 白云母原位rb-sr定年 北极地区构造演化
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四川甘洛铅锌矿集区闪锌矿Rb-Sr等时线年龄及其地质意义
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作者 魏宇 杨永峰 +7 位作者 柳维 王维华 张庆松 李金生 胡儒权 赵德坤 李俊俊 崔文东 《地质与勘探》 CAS CSCD 北大核心 2024年第3期482-493,共12页
四川甘洛铅锌矿集区位于扬子地块西南缘的川滇黔铅锌成矿带北段,是四川主要的铅锌产地,具有重要经济价值。为研究该矿集区铅锌成矿时代、成矿大地构造背景和成矿机制,以支撑区域找矿勘查,在区内选择赤普和尔呷地吉两个典型铅锌矿床开展... 四川甘洛铅锌矿集区位于扬子地块西南缘的川滇黔铅锌成矿带北段,是四川主要的铅锌产地,具有重要经济价值。为研究该矿集区铅锌成矿时代、成矿大地构造背景和成矿机制,以支撑区域找矿勘查,在区内选择赤普和尔呷地吉两个典型铅锌矿床开展闪锌矿Rb-Sr同位素体系研究,获得Rb-Sr等时线年龄246±17 Ma(MSWD=2.3),表明区内铅锌矿化作用发生于早三叠世,与古特提斯洋闭合时限吻合;闪锌矿(87Sr/86Sr)i值变化于0.71061~0.71393,高于幔源87Sr/86Sr值0.70355及峨眉山玄武岩87Sr/86Sr值0.704979~0.706938,低于基底岩石87Sr/86Sr值0.7243~0.7288,暗示成矿物质主要来源于地壳。综合前人研究,认为在古特提斯洋闭合背景下,强烈造山运动诱发盆地卤水深循环并萃取基底地层中的成矿物质,在峨眉山玄武岩岩浆活动的热动力条件下,含矿流体沿马拉哈断裂进一步迁移沉淀形成了赤普和尔呷地吉铅锌矿床。马拉哈深大断裂及造山作用派生的层间或断层破碎带、碳酸盐岩地层是甘洛地区主要的控矿要素。 展开更多
关键词 闪锌矿 rb-sr等时线年龄 成矿时代 物质来源 甘洛铅锌矿集区 四川
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The Rb-Sr isochron of ore and pyrite sub-samples from Linglong gold deposit, Jiaodong Peninsula, eastern China and their geological significance 被引量:47
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作者 Jinhui Yang Xinhua Zhou 《Chinese Science Bulletin》 SCIE EI CAS 2000年第24期2272-2277,共6页
Here we report the first direct Rb-Sr dating of pyrites and ores using sub-sampling from lode gold deposits in Linglong, Jiaodong Peninsula, which is a supra-large lode gold deposit and propose this as a useful geochr... Here we report the first direct Rb-Sr dating of pyrites and ores using sub-sampling from lode gold deposits in Linglong, Jiaodong Peninsula, which is a supra-large lode gold deposit and propose this as a useful geochronological technique for gold mineralization with poor age constraint. The Rb-Sr data of pyrites yield an isochron age of (121.6±8.1) Ma, whereas those of ore and ore-pyrite spread in two ranges from 120.0 to 121.8 Ma and from 110.0 to 111.7 Ma. Studies of characteristic of gold deposit and microscopy of pyrite and quartz indicate that the apparent ages of ore and ore-pyrite are not isochron ages, only mixed by two end members, i.e. the primitive hydrothermal fluids and wall rocks, whereas the isochron age of pyrite sub-samples constrains the age of gold mineralization (121.6±8.1) Ma, i.e. early Cretaceous, which is in good agreement with the published SHRIMP zircon U-Pb ages. 展开更多
关键词 LINGLONG GOLD deposit main stage of GOLD mineralization rb-sr isochron age PYRITE sub-sample.
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^(40)Ar/^(39)Ar and Rb-Sr isochron dating of the gold deposits on northern margin of the Jiaolai Basin,Shandong,China 被引量:25
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作者 张连昌 沈远超 +3 位作者 刘铁兵 曾庆栋 李光明 李厚民 《Science China Earth Sciences》 SCIE EI CAS 2003年第7期708-718,共11页
The Pengjiakuang, Dazhuangzi and Fayunkuang gold deposits, located on the northern margin of the Mesozoic Jiaolai Basin, east of Shandong Province, are controlled by a low-angle normal fault. Gold ores are typically b... The Pengjiakuang, Dazhuangzi and Fayunkuang gold deposits, located on the northern margin of the Mesozoic Jiaolai Basin, east of Shandong Province, are controlled by a low-angle normal fault. Gold ores are typically brecciated, veinlet and disseminated. The Ar-Ar and Rb-Sr isochron dating methods were adopted to date ores and lamprophyre dike. The results indicate that the age of the Pengjiakuang gold deposit is 117.33—118.42 Ma, that of the Dazhuangzi gold deposit is 117.39 Ma, and that of the Fayunkuang gold deposit is (128.49±7.2) Ma. The consistency in metallogenic age between the gold deposits on the margin of the Jiaolai Basin and the gold deposits (115—126 Ma) of the northern uplift area suggests that both were formed in the same metallogenic period. That is to say, the large-scale metallogeny of the Jiaodong region took place in late-Yanshannian ((120±10) Ma). 展开更多
关键词 AR-AR age rb-sr isochron gold metallogenic time NORTHERN MARGIN of the Jiaolai Basin.
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Rb-Sr and Sm-Nd Isochron Ages of the Dongmozhazhua and Mohailaheng Pb-Zn Ore Deposits in the Yushu area, southern Qinghai and Their Geological Implications 被引量:8
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作者 TIAN Shihong GONG Yingli +9 位作者 YANG Zhusen HOU Zengqian LIU Yingchao SONG Yucai XUE Wanwen LU Haifeng WANG Fuchun ZHANG Yubao ZHU Tian YU Changjie 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2014年第2期558-569,共12页
Located on the northeast margin of the Qiangtang terrane between the Jinshajiang suture zone and Bangonghu-Nujiang suture zone,the Dongmozhazhua and Mohailaheng Pb-Zn deposits in the Yushu area of Qinghai Province are... Located on the northeast margin of the Qiangtang terrane between the Jinshajiang suture zone and Bangonghu-Nujiang suture zone,the Dongmozhazhua and Mohailaheng Pb-Zn deposits in the Yushu area of Qinghai Province are representative Pb-Zn deposits of the Pb-Zn-Cu polymetallic mineralization belt in the northern part of the Nujiang-Lancangjiang-Jinshajiang area,which are in the front belt of the Yushu thrust nappe system.The formed environments of these two deposits are different from those of sediment-hosted base metal deposits elsewhere in the world.The authors hold that they were formed during the Indian-Asian continental collision and developed within the fold-thrust belt combined with thrust and strike-slip-related Cenozoic basins in the interior of the collisional zone.Studying on the metallogenic epochs of these two deposits is helpful to the understanding of ore-forming regularity of the regional Pb-Zn-Cu mineralization belt and also to the search for new deposits in this region.The age of the Dongmozhazhua deposit has been determined by the Rb-Sr isochron method for sphalerite residues,whereas the age of the Mohailaheng deposit has been determined by the Rb-Sr isochron method for sphalerite residues and the Sm-Nd isochron method for fluorite.The age of the Dongmozhazhua deposit is 35.0-±0.0 Ma ((87Sr/86Sr)0=0.708807) for sphalerite residues.The age of the Mohailaheng deposit is 32.2±0.4 Ma ((87Sr/86Sr)o=0.708514) for sphalerite residues and 31.8±0.3 Ma ((143Nd/144Nd)o=0.512362) for fluorite with an average of 32.0 Ma.Together with the regional geological setting during mineralization,a possible tectonic model for metallogeny of the Dongmozhazhua and Mohailaheng Pb-Zn deposits has been established.These two ages are close to the ages of the Pb-Zn deposits in the Lanping and Tuotuohe basins,indicating that it is possible that the narrow 1000-kilometer-long belt controlled by a thrust nappe system on the eastern and northern margins of the Tibetan plateau could be a giant Pb-Zn mineralized belt. 展开更多
关键词 rb-sr and Sm-Nd isochron ages thrust nappe system tectonic model Dongmozhazhua and Mohailaheng Pb-Zn deposits in the Yushu area Qinghai Province
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Auriferous Quartz Veins from the Dongping Gold Deposit, NW Hebei Province and Metallogenesis—Fluid Inclusion Rb-SrIsochron Evidence 被引量:1
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作者 莫测辉 王秀璋 程景平 《Chinese Journal Of Geochemistry》 EI CAS 1996年第3期265-271,共7页
The Dongping gold deposit, situated on the northern margin of the North China Platform, is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies. It is hosted in the inner contac... The Dongping gold deposit, situated on the northern margin of the North China Platform, is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies. It is hosted in the inner contact zone of an alkaline intrusion which was intruded into Archean metamorphic rocks and was formed not later than the Hercynian peried. Auriferous quartz veins of the deposit are dated with the fluid inclusion Rb-Sr isochron method at 103 ±4Ma, indicating that the gold deposit was formed in the Yenshanian period. 87Sr/86Sr sourcetracing shows the ore-forming materials came dominantly from alkaline intrusions. These results, combined with other isotope and REE data, suggest that the Dengping gold deposit is not a traditional magmatic hydrothermal deposit, but a reworked hydrothermal deposit related to heated and evoved meteoric water. 展开更多
关键词 石英型金矿床 铷同位素 锶同位素 稀土元素 rb-sr等时线
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Ultra-low procedural blank and the single-grain mica Rb-Sr isochron dating 被引量:17
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作者 LI Qiuli HEN Fukun +2 位作者 WANG Xiuli LI Xianghui LI Chaofeng 《Chinese Science Bulletin》 SCIE EI CAS 2005年第24期2861-2865,共5页
Both low procedural blank and high-precision measurements of isotopic ratios are crucial for the analysis of micro samples. This study reports a chemical procedure of ultra-low blank for the high precision measurement... Both low procedural blank and high-precision measurements of isotopic ratios are crucial for the analysis of micro samples. This study reports a chemical procedure of ultra-low blank for the high precision measurement of Sr isotopic ratios on micro samples (<1 ng level) using a new-type thermal ionization mass spectrometer IsoProbe-T, with a case study of single-grain Rb-Sr isochron dating on phlogopite from the Fuxian kimberlite in Liaoning Province. This method can be employed in studies of high resolution Rb-Sr geochronology and Sr isotopic geochemistry and thus will broaden application of the Rb-Sr isotopic system to earth sciences. 展开更多
关键词 地球科学 同位素比 稳定同位素地球化学 云母 角砾云橄岩 rb-sr同位素测年
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单种矿物单颗粒Rb-Sr同位素等时线定年的成矿年代学应用前景 被引量:1
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作者 何俊 齐泽秋 +4 位作者 李为用 王智毅 赵静欣 肖平 贺剑峰 《华东地质》 CAS 2024年第1期16-25,共10页
矿床成矿年龄的厘定一直是矿床学研究中的重点和难点,也是深入研究矿床成因的基础。然而,由于缺少合适的定年矿物、不同矿物之间同位素平衡以及矿物多期生长等因素,长期以来通过同位素定年技术确定成矿年龄还存在诸多限制。不同学者或... 矿床成矿年龄的厘定一直是矿床学研究中的重点和难点,也是深入研究矿床成因的基础。然而,由于缺少合适的定年矿物、不同矿物之间同位素平衡以及矿物多期生长等因素,长期以来通过同位素定年技术确定成矿年龄还存在诸多限制。不同学者或不同体系同位素定年结果常常存在明显差异,严重制约了矿床成因和成矿系统的深入研究,也难以为找矿勘查工作提供有效的理论依据。近年来,随着化学分离纯化技术和热电离质谱计性能的提高,可以准确测试低含量样品的同位素组成,进而为单颗粒矿物同位素定年提供了技术前提。文章简要回顾了Rb-Sr同位素等时线定年技术在矿床成因研究中的应用,重点介绍单种矿物单颗粒Rb-Sr同位素等时线定年技术的优点和难点。结果表明:相较于传统的Rb-Sr同位素等时线定年,单种矿物单颗粒等时线定年可以最大限度地满足“同时、同源、封闭、平衡”的同位素定年基本原则。在同种矿物不同颗粒中,母体与子体同位素87 Rb/86 Sr比值的差异可以达到最大范围,进而有助于获得高质量的等时线,得到高精度的成矿年龄。单种矿物单颗粒Rb-Sr同位素等时线定年技术能够有效地突破矿床定年的技术瓶颈,为诸多类型的热液矿床成矿年龄厘定和矿床研究提供重要基础。 展开更多
关键词 地质年代学 热液矿床 矿床定年 单颗粒矿物 rb-sr同位素
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内蒙古东珺银铅锌矿床成矿时代与地质背景:来自富碱花岗斑岩地球化学、锆石U-Pb及闪锌矿Rb-Sr年代学的制约
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作者 宋天骄 王策 +1 位作者 梁细荣 梁新权 《大地构造与成矿学》 EI CAS CSCD 北大核心 2024年第5期1040-1059,共20页
东珺银铅锌矿床位于大兴安岭中北部内蒙古额尔古纳市,是近几年发现的大型银铅锌多金属矿床。该矿床的成矿时代、成矿岩石以及构造背景一直不明确,本文对矿区内的出露的安山岩和隐伏的花岗斑岩开展了LA-ICPMS锆石U-Pb定年及岩石地球化学... 东珺银铅锌矿床位于大兴安岭中北部内蒙古额尔古纳市,是近几年发现的大型银铅锌多金属矿床。该矿床的成矿时代、成矿岩石以及构造背景一直不明确,本文对矿区内的出露的安山岩和隐伏的花岗斑岩开展了LA-ICPMS锆石U-Pb定年及岩石地球化学研究,并对银铅锌矿体中闪锌矿进行了Rb-Sr同位素定年。结果显示,安山岩喷出年龄为170.2±1.0 Ma、花岗斑岩结晶年龄为145.0±1.2 Ma以及矿体的成矿年龄为141.1±3.4 Ma。成矿年龄稍晚于花岗斑岩成岩年龄,表明成矿作用与晚侏罗世-早白垩世的岩浆活动具有密切的成因联系。花岗斑岩具有高硅(SiO_(2)=71.79%~72.88%)和富碱(Na_(2)O+K_(2)O=6.47%~8.23%)的特征,属于高钾钙碱性-钾玄岩系列。岩石的稀土元素总量较高(∑REE=195×10^(-6)~217×10^(-6)),具明显的Eu负异常(δEu=0.28~0.33),微量元素富集大离子亲石元素Rb、Th、U、K,明显亏损高场强元素Nb、Ta、Ti和过渡元素Sr、Ba,且具有高的10^(4)×Ga/Al(2.68~2.84)值,其全岩(^(87)Sr/^(86)Sr)i和ε_(Nd)(t)分别为0.704423~0.704768和+0.01~+1.94,锆石的ε_(Hf)(t)为+1.37~+8.29,表明该岩体具有A型花岗岩特征,其岩浆源区可能由地幔熔体和新生地壳熔体混合形成。结合区域地质和前人研究成果,认为东珺矿区花岗斑岩及相关的矿化作用形成于后碰撞伸展的构造环境,与晚侏罗世-早白垩世鄂霍茨克洋闭合后碰撞密切相关。 展开更多
关键词 东珺银铅锌矿床 锆石年代学 闪锌矿rb-sr 地球化学 蒙古-鄂霍茨克洋
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Uniform isochronous center of a class of higher degree polynomial differential systems
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作者 ZHOU Zheng-xin LU Fei-fei 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2024年第4期614-627,共14页
In this paper,we give the necessary and sufficient conditions for a class of higher degree polynomial systems to have a uniform isochronous center.At the same time,we prove that for this system the composition conject... In this paper,we give the necessary and sufficient conditions for a class of higher degree polynomial systems to have a uniform isochronous center.At the same time,we prove that for this system the composition conjecture is correct. 展开更多
关键词 composition conjecture center condition uniform isochronous center
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Bulk geochemistry,Rb-Sr,Sm-Nd,and stable O-H isotope systematics of the Metzimevin high-grade iron ore deposit,Mbalam iron ore district,southern Cameroon
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作者 Samndong Cyril Tufoin Cheo Emmanuel Suh +1 位作者 Tabod Charles Tabod George Lemewihbwen Ngiamte 《Acta Geochimica》 EI CAS CSCD 2024年第4期677-706,共30页
Bulk geochemistry,Sr,Nd,and O-H isotope systematics are reported for the first time on banded iron formation(BIF)-hosted high-grade iron ore at the northwestern segment of Congo Craton(CC).Located in Mbalam iron ore d... Bulk geochemistry,Sr,Nd,and O-H isotope systematics are reported for the first time on banded iron formation(BIF)-hosted high-grade iron ore at the northwestern segment of Congo Craton(CC).Located in Mbalam iron ore district,Southern Cameroon,Metzimevin iron ore deposit is a hematite-magnetite BIF system,dominated by SiO_(2)+Fe_(2)O_(3)(97.1 to 99.84 wt%),with low concentrations of clastic elements e.g.,Al_(2)O_(3),TiO_(2),and HFSE,depicting a nearly pure chemical precipitate.The REE+Y signature of the iron deposit displays strong positive Eu anomaly,strong negative Ce anomaly,and chondritic to superchondritic Y/Ho ratios,suggestive of formation by mixed seawater-high temperature hydrothermal fluids in oxidising environment.The^(87)Sr/^(86)Sr ratios of the BIF are higher than the maximum^(87)Sr/^(86)Sr evolution curves for all Archean reservoirs(bulk silicate earth,Archean crust and Archean seawater),indicating involvement of continentally-derived components during BIF formation and alteration.TheƐ_(Nd)(t)(+2.26 to+3.77)and Nd model age indicate that chemical constituents for the BIF were derived from undifferentiated crustal source,between 3.002 and 2.88 Ga.The variable and diverse O and H isotope data(−1.9‰to 17.3‰and−57‰to 136‰respectively)indicate that the Metzimevin iron ore formed initially from magmatic plumes and later enriched by magmatic-metamorphic-modified meteoric fluids.Mass balance calculations indicate mineralisation by combined leaching and precipitation,with an average iron enrichment factor of>2.67 and SiO_(2)depletion factor of>0.99.This is associated with an overall volume reduction of 28.27%,reflecting net leaching and volume collapse of the BIF protholith. 展开更多
关键词 Bulk geochemistry rb-sr SM-ND Mitzimevin High-grade iron ore
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Improved isochronous mass spectrometry with tune measurement
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作者 Han-Yu Deng Yuan-Ming Xing +5 位作者 Xu Zhou Yu-Hu Zhang Xin-Liang Yan Jin-Yang Shi Ting Liao Meng Wang 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第11期174-181,共8页
In conventional isochronous mass spectrometry(IMS)performed on a storage ring,the precision of mass measurements for short-lived nuclei depends on the accurate determination of the revolution times(T)of stored ions.Ho... In conventional isochronous mass spectrometry(IMS)performed on a storage ring,the precision of mass measurements for short-lived nuclei depends on the accurate determination of the revolution times(T)of stored ions.However,the resolution of T inevitably deteriorates due to the magnetic rigidity spread of the ions,limiting the mass-resolving power.In this study,we used the betatron tunes Q(the number of betatron oscillations per revolution)of the ions and established a correlation between T and Q.From this correlation,T was transformed to correspond to a fixed Q with higher resolution.Using these transformed T values,the masses of ^(63)Ge,^(65)As,^(67)Se,and ^(71)Kr agreed well with the mass values measured using the newly developed IMS(Bρ-IMS).We also studied the systematics of Coulomb displacement energies(CDEs)and found that anomalous staggering in CDEs was eliminated using new mass values.This method of T transformation is highly effective for conventional IMS equipped with a single time-of-flight detector. 展开更多
关键词 isochronous Mass Spectrometry Storage ring TUNE Natural chromaticity Nuclear mass measurement
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Βρ-defned isochronous mass spectrometry at the storage ring CSRe
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作者 Xu Zhou Meng Wang +3 位作者 Yu‑Hu Zhang Xiao‑Hong Zhou Xin‑Liang Yan Yuan‑Ming Xing 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第12期255-273,共19页
A novel technique of isochronous mass spectrometry(IMS),termed Bρ-defned IMS,was developed at the experimental cooler-storage ring CSRe in Lanzhou for the frst time.Two time-of-fight detectors were installed in a str... A novel technique of isochronous mass spectrometry(IMS),termed Bρ-defned IMS,was developed at the experimental cooler-storage ring CSRe in Lanzhou for the frst time.Two time-of-fight detectors were installed in a straight section of the CSRe,thereby enabling simultaneous measurements of the velocity and revolution time of each stored short-lived ion.This technique boosts the broadband precision,efciency,sensitivity,and accuracy of mass measurements of short-lived exotic nuclides.Using Bρ-defned IMS,the masses of^(22)Al,^(62)Ge,^(64)As,^(66)Se,and^(70)Kr were measured for the frst time,and the masses of^(65)As,^(67)Se,and other 21 nuclides were redetermined with improved accuracy.Mass data have been used in studies of relevant issues regarding nuclear structures and nuclear astrophysics.Herein,we review the development of experimental techniques and main physical results and outline plans for future experiments. 展开更多
关键词 Nuclear mass Storage ring Bρ-defned isochronous Nuclear structure Nuclear astrophysics
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南秦岭龙头沟金矿床石英Rb-Sr同位素测年及其地质意义
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作者 刘新伟 薛玉山 寸小妮 《地质找矿论丛》 CAS 2024年第4期469-477,共9页
龙头沟金矿位于柞(水)—山(阳)矿集区中部,矿床受构造控制,赋矿地质体主要为重晶石黄铁矿化石英脉,近年来相继在其外围发现五条沟、宽坪沟等金矿床,形成了一条重要的金矿带,成矿时代不清始终制约着对该矿床的进一步工作。为此,本文以主... 龙头沟金矿位于柞(水)—山(阳)矿集区中部,矿床受构造控制,赋矿地质体主要为重晶石黄铁矿化石英脉,近年来相继在其外围发现五条沟、宽坪沟等金矿床,形成了一条重要的金矿带,成矿时代不清始终制约着对该矿床的进一步工作。为此,本文以主成矿阶段石英流体包裹体Rb-Sr同位素测年为主要手段,开展成矿年代学研究。研究表明,该矿床是印支晚期构造热液活动的结果,其成矿作用可能开始于~266 Ma,以五条沟矿段249 Ma±42 Ma为代表达到高峰。南秦岭山凤断裂沿线,自海西期以来,构造-岩浆-热液活动呈现出三期活动显著特点,成岩成矿高峰期为280 Ma—300 Ma、200 Ma—220 Ma和140 Ma—160 Ma,丰富的岩浆热液活动不但给成矿作用带来大量的深部成矿物质,还直接控制着矿化强度、期次以及叠加成矿作用,龙头沟金矿与其他较大规模金矿一样,都是印支-燕山早期构造活动的结果,是南秦岭印支期金成矿作用的体现。 展开更多
关键词 龙头沟金矿床 石英流体包裹体rb-sr同位素 印支期 南秦岭成矿时代
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基于Rb-Sr同位素的铅锌多金属矿床成矿物质来源分析
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作者 宋睿 《中国金属通报》 2024年第14期65-67,共3页
文章旨在探讨川滇黔矿集区铅锌多金属矿床的成矿物质来源,通过Rb-Sr同位素体系进行深入研究。通过对区域地质背景、矿床地质特征、样品采集与分析方法的详细阐述,结合同位素地球化学数据,对成矿物质来源进行了综合分析。研究表明,该区... 文章旨在探讨川滇黔矿集区铅锌多金属矿床的成矿物质来源,通过Rb-Sr同位素体系进行深入研究。通过对区域地质背景、矿床地质特征、样品采集与分析方法的详细阐述,结合同位素地球化学数据,对成矿物质来源进行了综合分析。研究表明,该区铅锌多金属矿床的成矿物质具有多元来源特征,主要为壳源和幔源物质的混合。这一发现对于理解该区域成矿作用及找矿预测具有重要意义。 展开更多
关键词 rb-sr同位素 铅锌多金属矿床 成矿物质来源 川滇黔矿集区
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玉树地区东莫扎抓和莫海拉亨铅锌矿床Rb-Sr和Sm-Nd等时线年龄及其地质意义 被引量:57
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作者 田世洪 杨竹森 +14 位作者 侯增谦 刘英超 高延光 王召林 宋玉财 薛万文 鲁海峰 王富春 苏嫒娜 李真真 王银喜 张玉宝 朱田 俞长捷 于玉帅 《矿床地质》 CAS CSCD 北大核心 2009年第6期747-758,共12页
青海玉树地区的东莫扎抓和莫海拉亨铅锌矿床是"三江"北段铜铅锌多金属成矿带铅锌矿床的典型代表,处于玉树逆冲推覆构造带的前锋带位置。本文利用单矿物闪锌矿和共生矿物组合黄铁矿与方铅矿Rb-Sr等时线方法以及共生矿物组合闪... 青海玉树地区的东莫扎抓和莫海拉亨铅锌矿床是"三江"北段铜铅锌多金属成矿带铅锌矿床的典型代表,处于玉树逆冲推覆构造带的前锋带位置。本文利用单矿物闪锌矿和共生矿物组合黄铁矿与方铅矿Rb-Sr等时线方法以及共生矿物组合闪锌矿与黄铁矿Sm-Nd等时线方法测定东莫扎抓矿床的成矿时代为34.7~35.7Ma,平均为35Ma;利用单矿物闪锌矿和共生矿物组合闪锌矿与方铅矿Rb-Sr等时线方法以及单矿物萤石和共生矿物组合方解石与萤石Sm-Nd等时线方法测定莫海拉亨矿床的成矿时代为31.8~33.9Ma,平均为33Ma,表明2个矿床的成矿时代基本一致,为同期同源成矿作用的产物。结合区域成矿地质背景,建立了2个矿床的构造控矿模式。此外,本文获得的玉树地区典型铅锌矿床的成矿时代与"三江"南段兰坪盆地和"三江"北段沱沱河盆地铅锌矿床的成矿时代相近,证明青藏高原东部和北部受逆冲推覆控制的长达1000km的狭长地带有望成为一条巨型Pb-Zn成矿带。 展开更多
关键词 地球化学 rb-sr等时线 Sm-Nd等时线 共生矿物组合 成矿时代 逆冲推覆构造 构造模式 青海玉树东莫扎抓和莫海拉亨铅锌矿床
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