西藏米拉山地区铜钼矿化特征及找矿前景浅析

<正>西藏米拉山地区位于世界三大斑岩铜矿成矿域之一的特提斯-喜马拉雅成矿域,其大地构造位于冈底斯-念青唐古拉板片,是东特提斯构造域中晚古生代以来具有独特演化历程的一个多岛弧碰撞造山带(潘桂棠,1997)。不同演化阶段所形成的"火山弧"、"弧内盆地"、"岩浆弧"等成矿构造在空间上叠置,构成了"重叠式"火山-岩浆弧(姚鹏,2002)。笔者从西藏米拉山地区铜钼矿的矿床地质特征出发,结合区域地球理化特征等分析西藏米拉山地区铜钼矿矿化及找矿前景。     

西藏区域地质基本特征

西藏是青藏高原主体,大地位置居于南,北大陆之间的阿尔插斯－喜马拉雅巨型山系东段,是特提斯构造域的组成,部分。     

东特提斯地质调查研究进展综述

以青藏高原为主体的东特提斯构造演化一直是国内外地学研究中关注的重大科学问题。为了更全面、更深入地认识青藏高原及东特提斯构造域的形成演化历史,本文在综述前人有关特提斯构造域时空演变和演化阶段研究的基础上,重点总结了近年来1∶5万区域地质调查中取得的最新研究进展,提出昌宁-澜沧构造带原-古特提斯连续演化、南冈底斯构造带古-新特提斯连续演化新认识,构建了青藏高原及东特提斯构造域大陆边缘多岛弧盆系时空格局和原、古、新三阶段构造演化模式。     

雅鲁藏布江缝合带中段构造特征及成因模式新见解

雅鲁藏布江缝合带中的蛇绿岩在西藏南部不同地段,表现形式并不相同.通过对缝合带中段的构造特征及蛇绿岩组合特征的深入研究,认为印度板块的大陆地壳北缘具有特殊的波状弯曲的几何边界--东西两端为向北突出的犄角,构造结之间为向南突出的弧形边界.这种特殊的边界条件,在新特提斯洋俯冲碰撞过程中,新特提斯洋首先在突出结点处完成关闭,而...     

西藏羌塘南缘早白垩世普让岩体的成因与成矿意义

<正>班公湖-怒江缝合带是西藏腹地重要构造分界线,是研究中特提斯洋陆转换、盆山耦合的理想地区之一,因而备受地质学家们的关注(Zhu et al.,2011;李光明等,2011)。普遍研究认为中生代是中特提斯洋构造体制的重要转折阶段,其两侧出露的中生代岩浆岩正是这一构造演化事件的岩浆响应。因此,对该时期的岩浆岩剖析能够深化了解班公湖-怒江缝合带中生代的构造格局与地质演化。近年地质调查发现羌塘南缘的     

西藏成煤大地构造基本特征——西藏板块构造及其演化

西藏是介于古代南北大陆板块之间的过渡地带,自石炭纪以来,依次经历了前特提斯洋→古特提斯洋→特提斯洋的兴衰变迁过程:金沙江、怒江、雅鲁藏布三条缝合线分别是不同地史时期南北大陆坂块的分界线。本文总结了西藏板块构造的基本特征,论述了板块构造对西藏成煤条件的控制作用,认为西藏板块构造的特殊演化经历,是造成西藏各成煤期含煤性普遍不好的主要根源。指出昌都板片成煤条件相对较好,是西藏的主要找煤远景区。     

雅鲁藏布江蛇绿岩带的康金拉铬铁矿中发现金刚石

西藏罗布莎铬铁矿床位于特提斯-喜马拉雅构造带的东端,即西藏雅鲁藏布江蛇绿岩带的东段.它在区域构造上受控于雅鲁藏布江缝合带,北侧为冈底斯-念青唐古拉构造带,南与喜马拉雅构造带毗邻.罗布莎蛇绿岩分布在拉萨东南大约200 km,东西走向延长43 km,最宽处4 km,面积约70 km2.     

西藏蒙亚啊铅锌矿床成矿地质特征

<正>蒙亚啊铅锌矿床是念青唐古拉-冈底斯成矿带门巴-金达铅锌矿铜银钼多金属矿集区之中的典型矿床,构造上隶属于西藏特提斯构造域冈底斯-念青唐古拉地块中南部,冈底斯弧背断裂垄中段中东部。行政区域上隶属西藏自治区嘉黎县绒多乡。唐菊兴等(2009)提到,西藏冈底斯成矿带的成矿地质背景、矿床地质研究和资源潜力评     

西藏措勤县诺仓地区金元素地球化学特征及找矿方向

<正>西藏冈底斯构造带位于特提斯(地中海-喜马拉雅山)构造带的东南部,该构造带从前寒武纪到现今第四纪均不间断地受到大型构造运动的影响,所以此地区的岩浆岩具有时间上的多期次性、空间上的分带性(王四利、赵宝光等2014)。西藏措勤县诺仓地区恰好位于冈底斯岩浆岩构造带,该地区的岩石类型复杂,形成环境多样,为该区域成为富矿聚集区提供了先期矿质来源和成矿空间条件。西藏诺仓地区金元素异常区主要出露林子宗群典中组(E1d)及古新世二长花岗岩(E1ηγ)和古新     

西藏松多古特提斯洋研究进展与存在问题

青藏高原古特提斯构造域的演化过程一直是国内外地学研究关注的前沿和热点,冈底斯中部松多地区因榴辉岩带的发现,使其成为近年来国内外研究者关注的焦点地区之一。为了更好认识青藏高原古特提斯洋的构造演化历史,本文在综述前人研究的基础上,系统地总结了近年来1∶5万区域地质调查中取得的最新研究进展,初步讨论了唐加-松多地区俯冲增生杂岩带的物质组成和时代。研究表明,西藏冈底斯中部唐加-松多地区保存了相对完整的与古特提斯洋演化以及洋陆转换密切相关的混杂岩,是恢复和反演古特提斯洋演化的理想靶区。松多古特提斯洋洋壳及其消亡的地质记录主要包括晚古生代唐加-松多蛇绿岩、中二叠世洋岛残片、高压变质带、晚三叠世—早侏罗世岩浆作用以及晚三叠世—早侏罗世磨拉石建造。在上述工作基础上,初步探讨了松多古特提斯洋的演化过程,这些地质记录对恢复和反演青藏高原古特提斯构造演化研究具有重要意义。     

MULTIPLE ISLAND ARC-BASIN SYSTEM AND ITS EVOLUTION IN GANGDISE TECTONIC BELT,TIBET

MULTIPLE ISLAND ARC-BASIN SYSTEM AND ITS EVOLUTION IN GANGDISE TECTONIC BELT,TIBET     

中国地质构造发展历程

<正> 中国位于亚洲大陆的东南部,地跨几个洲际性构造单元的交汇部位。在地质历史上,它经历了多次构造变革逐步演化为目前这种复杂的构造格局。北部的准噶尔—兴安构造带属中亚—中蒙地槽褶皱带的一部分;中部为塔里木—中朝地台;青藏高原的大部分属巨型古地中海构造带中段,喜马拉雅地区属印度地台北缘;东部则隶属于中新生代的环太平洋构造带。     

The Cretaceous System in China

This paper provides an outline of Cretaceous stratigraphy and paleogeography in China, which is based on rich data obtained from recent researches. Cretaceous deposits are widespread in China. Most strata are of nonmarine origin and marine sediments occur only in Tibet, western Tarim Basin of Xinjiang, Taiwan and limited localities of eastern Heilongjiang. All deposits are rich in fossils and well-constrained biostratigraphically. The stratigraphic successions of different regions are illustrated, and general stratigraphic division and correlation have been introduced. The marine deposits are described in the Tibetan Tethys, Kashi-Hotan Region of Xinjiang, eastern Heilongjiang, western Yunnan and Taiwan; the nonmarine deposits are outlined from northeast China, southeast China, southern interior China, southwest China, the Shaanxi-Gansu-Ningxia region, and northwestern China intermontane basins. The sedimentary facies and paleogeography are diversified. In Tibet the basin evolution is largely related to the subduction and collision of the Indian Plate against the Eurasian Continent, and shows a tectonic evolution in the Cretaceous. Foraminifera are a dominant biota in the Tibet Tethys. Nonmarine sediments include variegated and red beds, coal- or salt-bearing horizons, and volcanic rocks. These deposits contain diverse and abundant continental faunas and floras, as well as important coal and oil resources. The Cretaceous stratigraphy and paleogeography in China have presented a foundation for geological studies.     

藏东江达中石炭世弧火山岩的厘定及其构造意义

金沙江特提斯洋盆是三江地区重要的洋盆之一,然而目前对于金沙江洋壳俯冲时限认识不一,弧火山岩对限定洋壳的俯冲消减过程具有重要意义.在西藏东部江达地区首次识别出一套中石炭世晚期的火山岩,主要岩性为玄武岩及安山岩,安山岩锆石U-Pb年龄为332±3.3 Ma（MSWD=2,n=14）,指示该火山活动为中石炭世晚期.江达火山岩SiO₂含量为45.65%~55.73%,具有高Al₂O₃含量（15.48%~16.79%）,TiO₂含量为0.82%~1.12%,富Na低K;轻重稀土分异明显,无δEu异常,强不相容元素Th、U等富集,高场强元素Nb、Ta等亏损,具有弧火山岩的地球化学性质.安山岩锆石ε_Hf（t）值为较均一的正值（+11.0~+15.6）,指示岩浆源区为受到富集组分影响的岩石圈地幔.研究表明江达中石炭世晚期火山岩形成于岛弧的构造环境,其火山活动与金沙江特提斯洋壳俯冲消减过程有关;结合区域地质资料认为金沙江特提斯洋壳在332 Ma之前已经开始了俯冲消减活动,进而为金沙江特提斯洋演化过程提供了岩石学证据.      

东海盆地中、新生代盆架结构与构造演化

基于地貌、钻井、岩石测年和地震等资料,分析盆地地层分布、盆架结构、构造单元划分和裂陷迁移规律,结果表明东海盆地由台北坳陷、舟山隆起、浙东坳陷、钓鱼岛隆褶带和冲绳坳陷构成,是以新生代沉积为主、中生代沉积为辅的大型中、新生代叠合含油气盆地;古元古代变质岩系构成了盆地的基底。该盆地不仅是印度-太平洋前后相继的动力体系作用下形成的西太平洋沟-弧-盆构造体系域一部分,而且也是古亚洲洋动力体系作用下形成的古亚洲洋构造域和特提斯洋动力体系作用下形成的特提斯洋构造域一部分,晚侏罗世至早白垩世经历了构造体制转换,盆地格局发生重大变革,早白垩世以前主要受古亚洲-特提斯洋构造体制影响的强烈挤压造山和地壳增厚作用演变为早白垩世以来主要受太平洋构造体制控制的陆缘伸展裂陷和岩石圈减薄作用,经历侏罗纪古亚洲-特提斯构造体制大陆边缘拗陷和白垩纪以来太平洋构造体制弧后裂陷两大演化阶段。白垩纪以来太平洋构造体制的弧后裂陷演化阶段可细分为早白垩世至始新世裂陷期、渐新世至晚中新世拗陷期和中新世末至全新世裂陷期。     

Petrology,geochemistry, and geochronology of mafic rocks from the Taoxinghu Devonian ophiolite,LongmuCo–Shuanghu–Lancang suture zone,northern Tibet: evidence for an intra-oceanic arc–basin system

Abstract

A newly discovered Devonian ophiolite located in the Taoxinghu area of central Qiangtang on the Qinhai–Tibet Plateau is described. The ophiolite consists of gabbro and diabasic dikes, and invasive cumulate gabbros-leucogabbros. The ophiolite has undergone greenschist facies metamorphism and minor deformation. Dating of the metagabbro by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U–Pb techniques yielded a weighted mean age of 367.2 ± 3.3 Ma (Late Devonian). Whole-rock geochemical analyses show that the rocks belong to the tholeiite series, with weak depletion in light rare-earth elements (LREEs), almost no Eu anomalies, weak enrichment in large-ion lithophile elements (LILEs), depletion in Nb and Ta, and weak negative Hf and Ti anomalies. These characteristics are similar to those of back-arc basin basalts. Together, these characteristics suggest that the rocks of the Devonian ophiolite formed by ~30% partial melting of spinel lherzolite, which was enriched by interaction with aqueous fluids during the late-generation phases; there is no evidence of subduction-related melting. The Devonian ophiolite rocks in the Taoxinghu area were first discovered in the LongmuCo–Shuanghu–Lancang suture zone. Detailed geochemical analyses show that the rocks formed in a back-arc ocean basin environment, indicating that the LongmuCo–Shuanghu–Lancang suture zone in central Qiangtang represents a Late Devonian intra-oceanic subduction zone in the Palaeo–Tethys Ocean. The discovery of the central Qiangtang Devonian ophiolite provides essential data for understanding the evolutionary history of the Palaeo–Tethys Ocean, and for identifying and understanding the roles of the different tectonic units on the Qinghai–Tibet Plateau.     

Tectonic Setting and Nature of the Provenance of Sedimentary Rocks in Lanping Mesozoic- Cenozoic Basin： Evidence from Geochemistry of Sandstones

The geochemical composition of sandstones in the sedimentary basin is controlled mainly by the tectonic setting of the provenance, and it is therefore possible to reveal the tectonic setting of the provenance and the nature of source rocks in terms of the geochemical composition of sandstones. The major elements, rare-earth dements and trace elements of the Mesozoic-Cenozoic sandstones in the Lanping Basin are studied in this paper, revealing that the tectonic settings of the provenance for Mesozoic-Cenozoic sedimentary rocks in the Lanping Basin belong to a passive continental margin and a continental island arc. Combined with the data on sedimentary facies and palaeogeography, it is referred that the eastern part of the basin is located mainly at the tectonic setting of the passive continental margin before Mesozoic, whereas the western part may be represented by a continental island arc. This is compatible with the regional geology data. The protoliths of sedimentary rocks should be derived from the upper continental crust, and are composed mainly of felsic rocks, mixed with some andesitic rocks and old sediment components. Therefore, the Lanping Mesozoic-Cenozoic Basin is a typical continental-type basin. This provides strong geochemical evidence for the evolution of the paleo-Tethys and theb asin-range transition.     

全球特提斯域煤系烃源岩发育特征及其控制因素

特提斯域构造活动背景控制下发育一系列煤系烃源岩发育盆地,且环太平洋带古近纪和新近纪煤多以“富氢”为特征,生烃潜力巨大,这一类煤系是我国东南沿海含油气盆地重要的烃源岩,因此,对特提斯背景下的煤系烃源岩发育特征及其控制因素进行系统总结尤为重要。通过系统分析特提斯域煤系烃源岩的发育时代、环境、地球化学特征及生物标志化合物特征,归纳总结影响煤系烃源岩发育的控制因素,明确煤系烃源岩的有利发育条件及优质源岩形成的控制因素。结果表明:特提斯域控制下的煤系烃源岩主要发育于东南亚沿海地区拉张背景下的盆地,多发育于断陷时期的海陆过渡相沉积环境,发育年代与特提斯构造活动时期吻合;煤系烃源岩发育受古植物、古环境、岩相古地理、陆源有机质供给、构造活动强度、沉积–沉降速率等多因素共同控制,各因素相互联系,相互影响,将其归纳为母源因素、构造–沉积因素及保存因素3类;富含壳质组和富氢镜质体的植物类型是富氢煤形成的必要母源条件,有利的聚煤环境及稳定构造背景是煤系烃源岩大规模发育的关键因素,合适的水体条件和还原环境是有机质得以保存的重要因素;我国东南沿海盆地煤系烃源岩生烃潜力巨大,东海盆地西湖凹陷煤系富含树脂体,珠江口盆地煤系富含孢子及花粉,琼东南盆地发育广泛的煤系泥岩,勘探前景巨大。      

西藏冈底斯带中部南木林地区林子宗群火山岩锆石U-Pb年龄和地球化学特征

林子宗群火山岩广泛分布在冈底斯带上,其岩石学特征及所代表的区域不整合事件被认为与特提斯洋俯冲消减到印度-亚洲大陆碰撞转变有关。对冈底斯带南木林地区的林子宗群火山岩进行了LA-ICP-MS锆石U-Pb测年及地球化学研究,获得林子宗群火山岩帕那组LA-ICP-MS锆石U-Pb年龄为46.08±0.47Ma、49.00±1.30Ma,对比冈底斯带其他地区已发表的年龄数据,认为印度-亚洲大陆碰撞(在西藏南部)的时间,东部可能依次早于中部和西部。地球化学特征表明,冈底斯带南木林地区林子宗群火山岩具有碰撞后地壳加厚背景下产生的弧火山岩特征,应为新特提斯洋俯冲消减到印度-亚洲大陆碰撞构造背景下形成的。     

GEODYNAMICS OF SUPERLARGE DEPOSITS IN CHINSES YUNNAN-GUIZHOU-GUANGXI ON THE EASTERN MARGIN OF THE QINGZANG PLEAUTAN

GEODYNAMICS OF SUPERLARGE DEPOSITS IN CHINSES YUNNAN-GUIZHOU-GUANGXI ON THE EASTERN MARGIN OF THE QINGZANG PLEAUTANNNSFC (973Hi techProjects;;No 19990 432 10 )andFundsforDoctoralSupervisorsoftheStateEducation departmentofChina