北阿尔金红柳沟-拉配泉构造混杂岩带东段的结构、构造          下载免费PDF全文

查显锋  李荣社  辜平阳  计文化  陈锐明  张海迪 《中国地质调查》2015,2(8):35-42

红柳沟-拉配泉蛇绿混杂岩带是阿尔金北部早古生代重要的板块构造边界,带内物质组成复杂,构造形迹发育,区内岩浆活动频繁,是开展板块俯冲边界特征、构造演化过程及区域构造格架再造等方面研究的重要场所。北阿尔金安南坝一带1:5万地质调查工作对红柳沟-拉配泉构造混杂岩带进行了构造-岩性填图,全面揭示了红柳沟-拉配泉蛇绿混杂岩带空间展布、物质组成、结构-构造特征。结合典型构造剖面及构造变形研究,对阿尔金早古生代构造过程及区域构造演化进行了探讨,为全面认识构造混杂岩带的结构、构造提供了可借鉴的工作经验。  相似文献   

西昆仑麻扎构造混杂岩的组成及其地质意义   总被引：5，自引：0，他引：5  

李博秦  计文化  边小卫  王峰  李伟 《现代地质》2007,21(1):78-86

西昆仑麻扎构造混杂岩带是1∶25万《麻扎幅》区域地质调查过程中发现并厘定的。岩块主要由火山弧杂岩、与弧相关的沉积建造和外来岩块3部分15个块体组成。各块体之间均为断层接触。基质分布在岩块的边部,主要由构造片岩和糜棱岩等组成。它包含着古洋壳消减过程中的一些重要信息。对构造混杂岩内角闪石英闪长岩进行SHRIMP测年,结果为(338±10）Ma,为早石炭世。麻扎构造混杂带的发现和研究,不仅丰富了麻扎-康西瓦缝合带的内容,而且将该带的演化时限提前到早石炭世,为西昆仑造山带研究提供了基础资料。  相似文献   

Graphite‐schist blocks in the Franciscan Mélange,San Simeon,California: Evidence of high‐P metamorphism          下载免费PDF全文

E. Ukar  M. Cloos 《Journal of Metamorphic Geology》2016,34(3):191-208

The seacliff exposure at San Simeon, California, contains graphite‐schist blocks in a shale‐matrix, an undocumented lithology within the Franciscan mélange. Thirty graphite‐schist blocks were studied to discover all the varieties in this classic locality of mélange. Based on their mineralogical assemblage and composition, and textural characteristics the graphite‐schists in San Simeon are subdivided into two main types (Type I and II) with two subdivisions each (A and B). Type IA and IIA blocks are the most abundant. Type IA graphite‐schists are siltstone/fine greywacke‐like, preserve sedimentary textures, and lack lawsonite. Type IB graphite‐schists are mineralogical and texturally similar to Type IA schists, but are finer grained siltstone and shale. Type IIA graphite‐schists are compositionally layered and contain quartz‐ and albite‐rich layers and dark graphite‐ and intergrown mica/chlorite‐rich layers. Nine out of the 15 Type IIA blocks contain lawsonite. Two Type IIA blocks also contain aragonite (+calcite) in veins. Type IIB graphite‐schists are mostly composed of quartz and minor graphite, intergrown chlorite and white mica, and white mica pseudomorphs after lawsonite. The phengite content of mica in Type IIA blocks is higher than that of mica in Type IA graphite‐schists, confirming they were metamorphosed under high‐P/low‐T conditions. Type IA blocks were recrystallized between 200 and 250 °C at <~3 kbar; whereas, Type IIA blocks were metamorphosed under higher pressure conditions, probably at 250–300 °C and 3–5 kbar. Most likely both types of graphite‐schists were derived from a similar layered siltstone/fine greywacke/shale protolith. Organic matter‐rich sediments deposited in the trench axis were subducted along with oceanic crust during Franciscan subduction. Type I graphite‐schists were subducted to depths <10 km, whereas Type II graphite‐schists were subducted to depths ~15 km where they were underplated under high‐P conditions. The graphitic metasedimentary rocks were juxtaposed with mafic lithologies from the subducted oceanic crust that were metamorphosed to blueschist facies and retrograded to greenstone as they returned to the surface in the subduction channel shear zone.  相似文献   

东昆仑南缘布青山构造混杂岩带早古生代白日切特中酸性岩浆活动:来自锆石U-Pb测年及岩石地球化学证据   总被引：12，自引：2，他引：10       下载免费PDF全文

刘战庆  裴先治  李瑞保  李佐臣  陈国超  陈有炘  高景民  刘成军  魏方辉  王学良  张刚 《中国地质》2011,38(5):1150-1167

在1∶50000地质填图基础上,运用剖面测制、岩石学、岩石地球化学及LA-ICP-MS锆石U-Pb法测年等方法,对东昆仑南缘布青山构造混杂岩带内的白日切特中酸性岩浆岩岩块进行详细研究。结果表明:白日切特剖面中酸性岩浆岩岩块主要由花岗闪长岩岩块和中酸性火山岩岩块组成,其中花岗闪长岩锆石206Pb/238U加权平均年龄为(441±6)Ma(MSWD=0.76),流纹斑岩锆石206Pb/238U加权平均年龄为(438±3)Ma(MSWD=2.0)。花岗闪长岩为高硅,富铝、钠,准铝质,钠质钙碱性系列;中酸性火山岩为硅饱和,铝质,钙碱性系列。二者稀土元素总量(∑REE)较低,LREE相对富集,HREE相对亏损,REE配分曲线呈LREE分馏明显,HREE分馏不明显右倾特征,花岗闪长岩基本上无铕异常,而中酸性火山岩具有弱的负铕异常,均与岛弧钙碱性系列的特征相似,与洋壳的俯冲消减作用有关,代表了在早志留世东原特提斯洋壳俯冲消减而形成的火山弧产物,为研究东特提斯洋演化进程提供了新证据。  相似文献   

东昆仑南缘布青山构造混杂岩带的地质特征 及大地构造意义   总被引：8，自引：1，他引：7  

刘战庆  裴先治  李瑞保  李佐臣  陈有炘  高景民  刘成军  王学良  魏方辉  张刚  杨忠智 《地质通报》2011,30(8):1182-1195

在1∶50000地质填图的基础上,运用详细的野外剖面测制、岩石组合分析、LA-ICP-MS锆石U-Pb同位素定年等研究手段,将东昆仑南缘布青山构造混杂岩划分为基质和构造混杂岩块。构造混杂岩块包括变质基底岩块、洋壳型岩块和岛弧型岩块。其中,洋壳型混杂岩块又细分为早古生代蛇绿岩(516.4Ma±6.3Ma)、晚古生代蛇绿岩(332.8Ma±3.1Ma)和海山/洋岛玄武岩;岛弧型混杂岩块细分为加里东期中酸性侵入岩岩块(441.1Ma±6.3Ma)和火山熔岩岩块。建立了东昆仑南缘布青山构造混杂岩带2套典型的古洋盆扩张、俯冲消减的物质组合,分别代表东原特提斯洋和东古特提斯洋的形成与演化,从而为研究东特提斯洋演化的进程提供了新证据。  相似文献   

Architecture and Kinematics of the Dabie Orogen,Central Eastern China   总被引：3，自引：0，他引：3  

XU Shutong  LIU Yican  CHEN Guanbao  WU Weiping Anhui Institute of Geology  Hefei  Anhui  Laboratory of Continental Dynamics of the Ministry of Land  Resources  Beijing 《《地质学报》英文版》2005,79(3):356-371

The geometry of the Dabie Mountains is manifested in terms of the distribution of petro-tectonic units in three dimensions. It is identified into three segments from east to west, four horizons in vertical profiles and eight petrotectonic units from north to south. Three segments are the east, middle and west segments. Four horizons, from top to bottom, are two different meta-tectonic melange in the uppermost part, underthrust basement and cover below them, and mantle at the bottom of the profiles. Eight petro-tectonic units from north to south are: (1) the hinterland basin, (2) the meta-flysch, (3) the ultramafic rock belt (UM) Sujiahe eclogite belt (SH), (4) eclogite belt 2 (Ec2) with most eclogites of continental affinity, (5) eclogite belt 1 (Ecl1) with some eclogite of oceanic affinity, (6) the Dabie complex or underthrust basement of the Yangtze continent, (7) the Susong and Zhangbaling Groups or underthrust cover of the Yangtze continent and (8) the foreland belt. The (3), (4) and (5) units belong to meta-tectonic melange. Some ultrahigh pressure metamorphic minerals such as coesite and micro-diamonds have been found in (3) and (4) units; a possible ultrahigh pressure mineral,clinozoisite aggregate pseudomorph after lawsonite, was found in unit (5). The three tectonic units are speculated to be coherent initially; the UM and SH units are suggested to be the root belt in the east, middle and west segments respectively.The kinematics of the Dabie orogen is divided into three stages: top-to-south thrusting during the eclogite-granulite facies metamorphism, top-to-north extension during the amphibolite metamorphic stage, and faults or shear bands of brittle deformation and greenschist facies metamorphism were formed in the post-orogenic stage since the Late Jurassic and the movement pictures of these faults is different from each other.  相似文献   

Petrogenesis of Permian basalt from Luoji region of Shangri-La，Western Yunnan     

ZOU Jinxi  LIU Xianfan  DENG Jianghong  HU Lin 《《地质学报》英文版》2013,87(Z1):201-202

  相似文献   

西准噶尔玛依勒山枕状熔岩地质特征及大地构造意义   总被引：5，自引：1，他引：4  

魏荣珠 《新疆地质》2010,28(3)

玛依勒蛇绿混杂岩带位于西准噶尔增生造山带西南缘.本文重点研究分布于玛依勒山一带枕状熔岩的地质地球化学特征和形成时代,为讨论西准噶尔造山带的形成演化提供依据.玛依勒山蛇绿混杂岩剖面中枕状熔岩、放射虫硅质岩和岩墙等出露较齐全,枕状熔岩为一套碱性玄武岩,源区为富集地幔,构造环境可能为洋盆中海山或洋岛.枕状熔岩Rb-Sr同位素等时线年龄为(435.3±6.5)Ma和(432.5±7.4)Ma,说明其形成时代为志留纪.奥陶—志留纪时,沿玛依勒一线可能出现较开阔的洋盆,现存的玛依勒枕状熔岩和超镁铁质岩代表了志留纪海山或洋岛残片.  相似文献   

青海沱沱河地区乌石峰蛇绿混杂岩的地球化学特征及其形成环境     

袁建国  杨立朋  高立湧 《化工矿产地质》2012,(1):15-25

青海沱沱河地区乌石峰蛇绿混杂岩位于西金乌兰-风火山逆冲带中。通过对其岩石学和全岩地球化学研究,探讨了蛇绿混杂岩的构造类型及其形成环境。晚古生代乌石峰蛇绿构造混杂岩的岩石组合以及蛇绿混杂岩中玄武岩类岩石(主要为辉绿岩及辉长岩)的地球化学特征对构造环境的指示表明:其地球化学特征与MORB相似,超基性岩和基性岩形成于大洋板内环境与洋中脊环境的复合构造环境中。是古特提斯洋洋盆残片,体现了古特提斯洋壳的闭合位置,是古特提斯洋在早二叠世末闭合过程中形成的增生楔的一部分。  相似文献   

对中国西部造山带地质研究若干问题的思考   总被引：6，自引：0，他引：6  

李荣社徐学义  计文化 《地质通报》2008,27(12):2020

从大陆研究的视角,认为大陆造山带地质研究是广义上的陆缘地质研究,阐述了陆缘多岛弧盆构造系统及其演化过程,提出造山带内时代相近的一组蛇绿混杂岩带是“古陆缘多岛弧盆格局”的残留,“古陆缘多岛弧盆构造系统”的基本残留形式在平面和剖面上都可能是“网结状”等认识。  相似文献