Geochronology and Petrogenesis for the Protolith of Biotite Plagioclase Gneiss at Lianghe, Western Yunnan   总被引：5，自引：0，他引：5  

CONG Feng  LIN Shiliang  ZOU Guangfu  XIE Tao  LI Zaihui  TANG Fawei  PENG Zhimin 《《地质学报》英文版》2011,85(4):870-880

In this paper,we report an integrated study of U-Pb age and Hf isotope compositions of zircons from biotite plagioclase gneiss at Lianghe in western Yunnan.The zircons preserved inherited core and rim texture.Igneous zircon grains and rims yielded a weighted mean ~(206)Pb/~(238)U age of 120.4±1.7 Ma,theirε_(Hf)(120 Ma)values were mainly negative ranging from-13.9 to-10.7,with Hf model ages between 1.9 Ga and 2.0 Ga,some zircons had positiveε_(Hf)(120 Ma)values ranging from 0.2 to 2.1.The inherited cores ...  相似文献   

Re–Os and U–Pb Geochronology of the Erlihe Pb–Zn Deposit, Qinling Orogenic Belt, Central China, and Constraints on Its Deposit Genesis     

ZHANG Fan  LIU Shuwen  LI Qiugen  SUN Yali  WANG Zongqi  YAN Quanren  YAN Zhen 《《地质学报》英文版》2011,85(3):673-682

The Erlihe Pb–Zn deposit is an important mine of the Pb–Zn metallogenic zone in the South Qinling Orogen. It has been considered a sedimentary exhalative deposit in previous investigations because the ore body occurs concordantly at the transitional location of an upright fold. Re and Os isotopic analyses for paragenetic pyrites with sphalerite and galena from the ore body have been used to determine the timing of mineralization and to trace the source of metallogenic materials. The Re–Os isotopic data of four pyrite samples construct an isochron, yielding a weighted average age of 226±17 Ma (mean square weighted deviation=1.7), which is considered the main mineralization age. A dioritic porphyrite vein sample, showing weaker mineralization, was also dated using the SHRIMP zircon U–Pb isotopic method to constrain the youngest metallogenic age of the ore deposit, because it distributes along a group of tensional joints cutting not only the upright fold in the deposit field, but also the main ore bodies. The dioritic porphyrite sample yields a weighted mean 206Pb/238U age of 221±3 Ma, which is slightly younger than the Re–Os isotopic isochron age of the pyrites, considered as the upper age limit of the mineralization, namely the ending age of the mineralization. The Os isotopic compositions of sulfide minerals distribute within a range between Os isotopic compositions of the crust and the mantle, indicating that the ore deposit can be derived from magma-related fluid, and the metallogenic materials are most likely derived from the mixing source of the crust and the mantle. The Erlihe Pb–Zn deposit and associated dioritic porphyrite vein, important records of Qinling tectonic–magmatism–mineralization activities, were formed during the Triassic collisional orogeny processes.  相似文献   

贵州梵净山白云母花岗岩锆石年代、铪同位素及对华南地壳生长的制约   总被引：7，自引：0，他引：7       下载免费PDF全文

王敏  戴传固  王雪华  陈建书  马会珍 《地学前缘》2011,18(5):213-223

贵州梵净山地区位于＂江南造山带＂西南段,出露地层为中新元古界梵净山群、青白口系板溪群、南华系及古生界地层。梵净山群已强烈褶皱,被青白口系板溪群角度不整合覆盖。浅色白云母花岗岩侵位于褶皱的梵净山群中;锆石原位LA-ICP-MS分析结果显示,其形成时代为（838.5±1.5）Ma。地球化学分析结果表明,其A/CNK值〉1....  相似文献   

U–Pb and Re–Os geochronology and geodynamic setting of the Dabaoshan polymetallic deposit, northern Guangdong Province, South China     

Lei Wang  Mingan Hu  Zhen Yang  Wenjun Qu  Jinlong Xia  Kaixu Chen 《Ore Geology Reviews》2011,43(1):40-49

The Dabaoshan polymetallic deposit in northern Guangdong Province contains iron, copper, lead, zinc, molybdenum, tungsten and sulfur mineral resources. Porphyry-type Mo(W) and skarn-type Mo-W mineralization occurs along the internal and external contact zones of the granodioritic porphyry, respectively. LA-ICP-MS U–Pb dating of zircons from two granodioritic porphyry samples yielded a weighted mean ²⁰⁶Pb/²³⁸U age of 175.8 ± 1.5 Ma (MSWD = 0.037) and 175.0 ± 1.7 Ma (MSWD = 0.41). They can be pooled together to yield a combined weighted age of 175.4 ± 1.6 Ma (MSWD = 0.26), which is interpreted as the emplacement age of the granodioritic porphyry. Re–Os dating of three molybdenite samples from porphyry and skarn ores yielded consistent model ages of 163.2 ± 2.3 Ma to 165.2 ± 2.4 Ma, with a weighted mean of 163.9 ± 1.3 Ma (MSWD = 0.81), which is the age of Mo–W mineralization. These ages are consistent with the molybdenite Re–Os model age (164.7 ± 3 Ma) measured by Mao et al. (2004a) for the stratiform Cu–Pb–Zn orebody, and they can yield a weighted mean of 164.0 ± 2.5 Ma (MSWD = 0.16). This implies that Mo–W and Cu–Pb–Zn mineralization in the Dabaoshan polymetallic deposit are the products of one mineralization event. The mineralization in the deposit coincides closely with that of Mo-polymetallic mineralization (164–149 Ma) elsewhere in the Nanling region, comprising an important polymetallic metallogenic belt of south China, and corresponds to the second episode of Mesozoic metallogenesis in South China. Combined with previous studies, we suggest that the Dabaoshan polymetallic deposit is related to post-collisional lithosphere extension in the Nanling region of South China. Geological data and Pb isotopic evolution diagrams, together with stable isotopic data of fluid inclusions (δ¹⁸O = − 3.75–7.0‰, δD = − 50.7 to − 56.1‰) and ore sulfides (δ³⁴S = − 2–3‰), suggest a genetic relationship between the Dabaoshan polymetallic deposit, the granodioritic porphyry and the dacitic porphyry. These data, combined with the Re content (64.7 to 102.4 ppm) of molybdenite, indicate that the ore-forming components were derived from mixed crustal and mantle sources.  相似文献   

阿尔泰南缘乌吐布拉克铁矿区花岗质岩石年代学及成因   总被引：7，自引：0，他引：7       下载免费PDF全文

张志欣  杨富全  柴凤梅  刘锋  耿新霞  吕书君  姜丽萍  钟天智 《地质论评》2011,57(3):350-365

本文对新疆阿尔泰南缘乌吐布拉克铁矿区斜长花岗岩和黑云母斜长花岗岩进行了锆石LA-ICP-MS U-Pb年龄测定,分别获得了385.6±2.3 Ma（MSDW=0.13）和387.7±2.1 Ma（MSDW=0.23）的谐和年龄,两者为中泥盆世早期同源岩浆侵入体。乌吐布拉克铁矿的形成与岩浆侵入活动密切相关,据此限定铁矿成矿时代略晚于388～386 Ma,为中泥盆世早期成矿。乌吐布拉克斜长花岗岩与黑云斜长母花岗岩均具有高硅（SiO2=66.01%～79.14%）、富钠贫钾（Na2O＞K2O）的特点。A/CNK〖HT4”〗{A/CNK=n(Al2O3)/\n(CaO)+n(Na2O)+n(K2O)]}值均小于1.1,表明两者为准铝质低钾花岗岩。微量元素表现为富集Th、Ta、Hf等高场强元素,亏损Rb 、Ba、K、Sr、P大离子亲石元素。稀土元素表现为轻稀土相对富集,轻重稀土元素分馏明显[(La/Yb)N=2.46～7.24],具有中等或强的Eu负异常。结合区域地质资料,认为乌吐布拉克矿区花岗岩形成于与板块俯冲有关的活动大陆边缘的陆缘弧环境中。  相似文献   

青海门源地区红沟铜矿床含矿基性火山岩LA-ICP-MS锆石U-Pb年龄   总被引：1，自引：0，他引：1  

王国强  李向民  徐学义  余吉远  孙吉明  武鹏 《中国区域地质》2011,(7):1060-1065

对红沟铜矿床含矿火山岩进行高精度锆石LA-ICP-MS U-Pb同位素测年,获得单颗粒锆石的加权平均年龄为443.2Ma±1.2Ma。红沟铜矿床形成时代为晚奥陶世,形成环境为晚奥陶世陆缘裂谷环境。高精度年龄的获得对于整个祁连山地区产于陆缘裂谷环境的铜多金属矿床的成矿时代和成因研究具有重要意义。  相似文献   

利用抗剪强度计算地基承载力特征值方法探讨          下载免费PDF全文

潘广灿  张金来  郜松杰 《探矿工程》2011,38(11):68-70,82

利用不同地层情况的计算实例,分别采用抗剪强度指标厚度加权平均法和附加应力面积法对地基承载力特征值进行计算,对计算结果进行分析,对不同的计算方法的理论原理进行了剖析,提出利用附加应力系数法计算抗剪强度指标标准值的结论。同时提出抗剪强度指标应采用不固结不排水剪指标,当持力层为粉土时应对其抗剪强度指标进行75%的折减的方法和建议。为合理利用抗剪强度指标计算地基承载力特征值提供了有益的参考。  相似文献   

甘肃北山红柳园地区泥盆系三个井组和墩墩山群LA-ICP-MS锆石U-Pb测年及其意义     

李向民  余吉远  王国强  武鹏  周志强 《中国区域地质》2011,(10):1501-1507

对甘肃北山红柳园地区三个井组下部玄武岩和墩墩山群安山质火山岩进行了LA-ICP-MS锆石U-Pb年龄测定,三个井组火山岩形成于420Ma±15Ma,相当于晚志留世;墩墩山群火山岩形成于367Ma±10Ma,相当于晚泥盆世。测年结果表明,晚志留世北山古生代洋盆已经俯冲消亡,并开始碰撞造山,而晚泥盆世墩墩山群火山岩则是北山早古生代洋盆碰撞造山后裂谷拉伸作用的产物,标志北山及相邻地区晚泥盆世进入到新的构造演化阶段——晚古生代板内伸展阶段。  相似文献   

滇西北中旬红山Cu多金属矿床花岗斑岩锆石LA—ICP—MSU—Pb定年及其地质意义   总被引：15，自引：0，他引：15  

王新松  毕献武  冷成彪  唐永永  兰江波  齐有强  沈能平 《矿物学报》2011,31(3):315-321

红山cu多金属矿床位于滇西北义敦岛弧南端的中旬岛弧,一直以来被认为是印支期夕卡岩型矿床。但近年研究发现,矿区内还发育有燕山晚期斑岩型Cu—Mo矿化作用。本文首次在红山矿区发现了燕山晚期的花岗斑岩,花岗斑岩锆石LA—ICP—MSU-Pb定年研究确定其年龄为（81．1±0．5）Ma,与斑岩型Cu—Mo矿化年龄（77±2Ma,辉钼矿Re一0s等时线年龄）在误差范围内非常接近,成岩与成矿作用之间具有密切的时空成因联系。红山Cu多金属矿床燕山晚期花岗斑岩成岩年龄与义敦岛弧造山后伸展环境下所形成的花岗岩浆成岩时代峰期（80Ma左右）相一致,表明中甸红山地区除存在与俯冲作用密切相关的印支期cu多金属成矿作用外,还存在燕山晚期形成于造山后伸展环境的花岗斑岩型Cu—Mo成矿作用。  相似文献   

云南个旧神仙水岩体锆石U—Pb年代学及岩石地球化学研究   总被引：1，自引：0，他引：1  

张颖  黄智龙  罗泰义  钱志宽 《矿物学报》2011,31(3):515-524

云南个旧地区花岗岩极其发育,且与锡成矿关系密切。其中个旧西区神仙水花岗岩体呈岩株状,岩性主要为碱长花岗岩和正长岩。岩石地球化学研究表明,神仙水花岗岩具有高硅、贫钙镁、富碱的特征;ω（TFeO）／ω（MgO）和ω（Na2O＋K2O）／ω（A12：O3）比值高。富集大离子亲石元素Rb、n、u、K、La、Nd和高场强元素zr、Hf,亏损Ba、sr、Ta、P、Ti。Eu负异常较强,轻稀土富集,重稀土相对亏损,稀土配分模式呈右倾海鸥型,岩石类型属于A型花岗岩。锆石LA—ICP．Ms定年结果表明神仙水花岗岩体形成于81Ma左右,相当于晚白垩世。根据区域地质和花岗岩地球化学特征,判断其形成于伸展构造环境。  相似文献