川西北雪宝顶钨锡铍矿床的成矿年代及其构造示踪意义   总被引：4，自引：2，他引：4       下载免费PDF全文

李建康  刘善宝  王登红  付小方 《矿床地质》2007,26(5):557-562

研究表明,川西北雪宝顶矿床的白云母40Ar/39Ar坪年龄为(189.9±1.8)Ma,说明雪宝顶矿床形成于印支晚期—燕山早期,是三叠纪华北板块与扬子板块碰撞的产物。文章通过雪宝顶矿床与甲基卡、可尔因和丹巴等伟晶岩型矿床的时空位置对比,并依据伟晶岩对大陆活动的示踪作用,推测中生代松潘-甘孜造山带的演化过程为:华北陆块、羌塘-昌都陆块分别与扬子陆块碰撞后,构造应力自北向南、自西向东逐步向松潘-甘孜地块的中心传递,雪宝顶、甲基卡、可尔因地区相继进入相对稳定发展阶段,构造应力最后在丹巴地区汇聚,形成丹巴白云母矿床。  相似文献   

四川丹巴伟晶岩型白云母矿床的成矿流体研究          下载免费PDF全文

李建康王登红  付小方 《地质学报》2007,81(7):986-994

四川丹巴伟晶岩型白云母矿床是我国第二大白云母产地,但其研究程度很低,形成机理的研究停留在定性推断的水平上,本文拟从流体的角度来研究其形成机理。丹巴北部的布衣沟位于白云母矿区的中心地带,自西向东穿过混合岩化变质带→部分混合岩化变质带→夕石化变质带,分布有蒋家→下蒋家→水大→二道桥等伟晶岩矿脉,其流体包裹体的均一温度峰值依次降低,CO2-H2O包裹体的数量逐渐减少,盐度有增高的趋势。碳、氢、氧同位素示踪出成岩成矿流体主要由携带深源碳的岩浆热液、建造水及脱碳反应产生的CO2组成。从蒋家→下蒋家→水大→二道桥伟晶岩脉,流体中的CO2/CH4和CO2/N2呈降低。这些特征显示出成岩成矿流体的演化过程:携带深源碳的岩浆热液自春牛场穹隆体的深部向外迁移,在部分混合岩化带与脱碳反应产生的CO2混合,在夕石带与建造水混合而稀释。因此丹巴白云母矿床属于“岩浆 变质”混合成因。  相似文献   

Geochemistry of S-type granitic rocks from the reversely zoned Castelo Branco pluton (central Portugal)     

I.M.H.R. Antunes  A.M.R. Neiva  M.M.V.G. Silva  F. Corfu 《Lithos》2008,103(3-4):445-465

The zoned pluton from Castelo Branco consists of Variscan peraluminous S-type granitic rocks. A muscovite>biotite granite in the pluton's core is surrounded successively by biotite>muscovite granodiorite, porphyritic biotite>muscovite granodiorite grading to biotite=muscovite granite, and finally by muscovite>biotite granite. ID-TIMS U–Pb ages for zircon and monazite indicate that all phases of the pluton formed at 310 ± 1 Ma. Whole-rock analyses show slight variation in ⁸⁷Sr/⁸⁶Sr_310 Ma between 0.708 and 0.712, Nd_310 Ma values between − 1 and − 4 and δ¹⁸O values between 12.2 and 13.6. These geological, mineralogical, geochemical and isotopic data indicate a crustal origin of the suite, probably from partial melting of heterogeneous Early Paleozoic pelitic country rock. In detail there is evidence for derivation from different sources, but also fractional crystallization linking some of internal plutonic phases. Least-squares analysis of major elements and modelling of trace elements indicate that the porphyritic granodiorite and biotite=muscovite granite were derived from the granodiorite magma by fractional crystallization of plagioclase, quartz, biotite and ilmenite. By contrast variation diagrams of major and trace elements in biotite and muscovite, the behaviours of Ba in microcline and whole-rock δ¹⁸O, the REE patterns of rocks and isotopic data indicate that both muscovite-dominant granites were probably originated by two distinct pulses of granite magma.  相似文献   

Petrographic, Chemical and B-Isotopic Insights into the Origin of Tourmaline-Rich Rocks and Boron Recycling in the Martinamor Antiform (Central Iberian Zone, Salamanca, Spain)   总被引：2，自引：0，他引：2  

PESQUERA  A.; TORRES-RUIZ  J.; GIL-CRESPO  P. P.; JIANG  S.-Y. 《Journal of Petrology》2005,46(5):1013-1044

Tourmaline in the Martinamor antiform occurs in tourmalinites(rocks with >15–20% tourmaline by volume), clasticmetasedimentary rocks of the Upper Proterozoic Monterrubio formation,quartz veins, pre-Variscan orthogneisses and Variscan graniticrocks. Petrographic observations, back-scattered electron (BSE)images, and microprobe data document a multistaged developmentof tourmaline. Overall, variations in the Mg/(Mg + Fe) ratiosdecrease from tourmalinites (0·36–0·75),through veins (0·38–0·66) to granitic rocks(0·23–0·46), whereas Al increases in thesame order from 5·84–6·65 to 6·22–6·88apfu. The incorporation of Al into tourmaline is consistentwith combinations of ^xAl(NaR)_–1 and AlO(R(OH))_–1exchange vectors, where ^x represents X-site vacancy and R is(Mg + Fe²⁺ + Mn). Variations in ^x/(^x + Na) ratios are similarin all the types of tourmaline occurrences, from 0·10to 0·53, with low Ca-contents (mostly <0·10apfu). Based on field and textural criteria, two groups of tourmaline-richrocks are distinguished: (1) pre-Variscan tourmalinites (probablyCadomian), affected by both deformation and regional metamorphismduring the Variscan orogeny; (2) tourmalinites related to thesynkinematic granitic complex of Martinamor. Textural and geochemicaldata are consistent with a psammopelitic parentage for the protolithof the tourmalinites. Boron isotope analyses of tourmaline havea total range of ¹¹B values from –15·6 to 6·8;the lowest corresponding to granitic tourmalines (–15·6to –11·7) and the highest to veins (1·9to 6·8). Tourmalines from tourmalinites have intermediate¹¹B values of –8·0 to +2·0. The observedvariations in ¹¹B support an important crustal recycling ofboron in the Martinamor area, in which pre-Variscan tourmaliniteswere remobilized by a combination of mechanical and chemicalprocesses during Variscan deformation, metamorphism and anatexis,leading to the formation of multiple tourmaline-bearing veinsand a new stage of boron metasomatism. KEY WORDS: tourmalinites; metamorphic and granitic rocks; mineral chemistry; whole-rock chemistry; boron isotopes  相似文献   

贵东岩体地质地球化学特征及其形成的构造环境识别   总被引：9，自引：1，他引：9  

李建红  卫三元  梁良  冯明月 《铀矿地质》2004,20(6):321-329

本文在研究贵东花岗岩岩体岩石矿物组合、结构构造等地质特征的基础上 ,运用花岗岩的岩石化学、微量元素和同位素等分析数据 ,采用目前广泛应用的几种岩石化学图解、微量元素和同位素图解等方法 ,判别了贵东岩体形成的构造环境为造山带后碰撞型  相似文献   

个旧锡矿区域地壳演化与成矿探讨   总被引：3，自引：0，他引：3  

谈树成  秦德先  陈爱兵  范柱国  薛传东  李俊  夏既胜  普传杰 《矿物学报》2004,24(2):157-163

个旧锡多金属矿床是驰名中外的特大型矿床，过去认为是燕山晚期“花岗岩岩浆期后气液矿床”。但通过探讨区域上前震旦纪地壳演化、震旦纪-早古生代地壳演化、泥盆纪-三叠纪地壳演化以及侏罗纪-第四纪地壳演化，以及与成矿之间的关系，发现个旧矿区至少经历了印支中晚期海底基性火山-沉积成矿、印支中晚期海底喷流热水沉积成矿、燕山晚期花岗岩叠加改造成矿以及喜山期陆相表生沉积成矿作用，厘定了个旧锡矿区的印支中晚期海底基性火山．沉积Sn-Cu-Zn(Au)矿床系列、印支中晚期海底喷流-沉积Sn-Cu-Pb-Zn矿床系列、燕山晚期花岗岩叠加改造Sn-Cu-W-Be-Bi-Pb-Zn-Ag矿床系列、喜山期陆相表生沉积砂矿矿床系列等4大矿床系列及12种矿床类型。  相似文献   

~(40)Ar/~(39)Ar dating of shear deformation of the Xianshuihe fault zone in west Sichuan and its tectonic significance   总被引：6，自引：1，他引：6  

ZHANG Yueqiao  CHEN Wen  & YANG Nong . Institute of Geomechanics  Chinese Academy of Geological Sciences  Beijing  China  . Institute of Geology  Chinese Academy of Geological Sciences  Beijing  China  . Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing  China 《中国科学D辑(英文版)》2004,47(9)

TheNW-SEstrikingXianshuihefaultzoneslicesthesoutheasternTibetanPlateauandconnectssoutheastwardwiththeAnninghe-Zemuhe-Xiaojiangfaultzone,whichformahuge,activesinistralstrike-slipfaultzone(fig.1).ThisfaultzoneisanimportantseismicfaultineastTibet[1-5].EarthquakegeologystudiesandoffsetpatternsofyounggeologicalfeatureshaveshownthatlateQuaternarysinistralsliprateoftheXianshuihefaultzonereaches13mm/a[1,2].TheXianshuhefaultzoneconsistsoftwomainbranches,theDaofufaultbranchinthewestandtheXianshuih…  相似文献   

A Sequence of Pan-African and Hercynian Events Recorded in Zircons from an Orthogneiss from the Hercynian Belt of Western Central Iberia--an Ion Microprobe U-Pb Study   总被引：1，自引：0，他引：1  

ZECK  H. P.; WINGATE  M. T. D.; POOLEY  G. D.; UGIDOS  J. M. 《Journal of Petrology》2004,45(8):1613-1629

Sensitive high-resolution ion microprobe U–Pb dating showsthat a biotite orthogneiss from the Hercynian belt of westerncentral Iberia contains 1000–300 Ma zircon. Older, 1000–570Ma ages within this range represent inherited, detrital materialamong which four age components may be recognized:  相似文献   

Mafic Pegmatites Intruding Oceanic Plateau Gabbros and Ultramafic Cumulates from Bolivar, Colombia: Evidence for a 'Wet' Mantle Plume?     

KERR  ANDREW C.; TARNEY  JOHN; KEMPTON  PAMELA D.; PRINGLE  MALCOLM; NIVIA  ALVARO 《Journal of Petrology》2004,45(9):1877-1906

The fault-bounded Bolívar Ultramafic Complex (BUC) onthe eastern fringes of the Western Cordillera of Colombia wastectonically accreted onto the western coast of South Americain the late Cretaceous–early Tertiary, along with pillowbasalts of the Caribbean–Colombian Oceanic Plateau (CCOP).The complex consists of a lower sequence of ultramafic cumulates,successively overlain by layered and isotropic gabbroic rocks.The gabbros grade into, and are intruded by, mafic pegmatitesthat consist of large magnesiohornblende and plagioclase crystals.These pegmatites yield a weighted mean ⁴⁰Ar–³⁹Ar step-heatingage of 90·5 ± 0·9 Ma and thus coincidewith the timing of peak CCOP volcanism. The chemistry of theBUC is not consistent with a subduction-related origin. However,the similarity in Sr–Nd–Pb–Hf isotopes betweenthe CCOP and the BUC, in conjunction with their indistinguishableages, suggests that the BUC is an integral part of the plume-derivedCCOP. The parental magmas of the Bolívar complex wereprobably hydrous picrites that underwent 20–30% crystallization.The residual magmas from this fractionation contained  相似文献   

巴彦诺尔公花岗岩体与乌力吉花岗岩体的地球化学特征及成矿意义   总被引：2，自引：0，他引：2  

王喜宽  张丽莉  廖蕾  丛立民 《华南地质与矿产》2004,(1):24-28

巴彦诺尔公花岗岩体和乌力吉花岗岩体均属二叠纪花岗岩，两岩体在地球化学组成上基本一致，均富Si02，K20和Al20。，富集轻稀土，而重稀土亏损。其差别是：前者属钙碱性岩石(σ=l.91)，较富集Fe，Mg，Ca，Cu，Cr，Sr，Ba和F，而后者为钙性岩石(σ=1.68)较富集W，As，Sb和Au等。两岩体不仅为其周围矿产的形成提供了充分的热液，也提供了丰富的物质来源。正是由于充分的热液活动和物质迁移以及后期富集形成了朱拉扎嘎大型金矿。  相似文献