吉林省安图县海沟金矿床控矿构造特征   总被引：2，自引：0，他引：2  

曾庆栋  戴薪义 《吉林地质》1996,15(2):36-44

海沟金矿是大型石英贫硫化物脉型金矿床。矿区侵入岩可划分为四个花岗岩单元，矿体（脉）在平、剖面上都具有斜列的特点。含金石英脉的产出和分布严格受ＮＮＥ－ＮＥ向断裂控制。金矿区控矿构造型式为ＥＷ向大断裂的派生断裂控制矿床，成矿构造序列划分为成矿前、成矿期、成矿后构造。构造对矿床（矿体）的控制作用主要表现为等距性构造控制矿脉分布；断裂多期活动对富矿体的控制。分析了断裂构造地球化学特征，表明成矿作用是以充填  相似文献   

黔南绿色花岗石资源及开发利用前景     

李毅 《矿产与地质》1996,(3)

黔南地区花岗石资源丰富。绿色花岗石矿体由辉长辉绿岩（内部岩相）、辉绿岩（过渡岩相）和辉绿玢岩（边缘岩相）以及钠长石脉岩组成，以过渡岩相辉绿岩体为石材主要开采对象。矿体厚度大，分布广，成荒率高，石材花色品种好，具有很大开发前景  相似文献   

Oxygen Isotope Exchange Kinetics Between Coexisting Minerals and Water in the Aral Granite Pluton of the Altay Mountains, Northern Xinjiang   总被引：2，自引：0，他引：2  

Liu Wei  Research Center of Mineral Resources Exploration  Chinese Academy of Sciences  Chinese Academy of Sciences  BeijingHe Baichu  Changsha Institute of Geotectonics  Chinese Academy of Sciences  Changsh  Hunanand Chen ZhenshengYichang Institute of Geology  Mineral Resources  Chinese Academy of GeologicalSciences  Yichang  Hubei 《《地质学报》英文版》1996,70(4)

Coexisting quartz, feldspar and biotite vary widely in their δ18O values and display a remarkable 18O/16O disequilibrium relation; especially, a quartz-feldspar reversal (△ 18OQUartz_feldspar< 0) exsists in the Aral granite pluton of the Altay Mountains, northern Xinjiang. The 18O / 16O exchange reaction definitely occurred between granite and water. Initial δ18O values of the granite and exotic fluid are evaluated by the mass balance consideration. The conventional method of discrimination between various magma derivations simply with δ18O values of either whole rock or separate minerals is misleading and unreliable. Experiments carried out by the authors show that the 18O / 16O exchange reaction is not accompanied by what geologists describe as petrological and mineralogical alteration effect. This decoupling relation implies that exchange reaction occurs at a relatively high temperature during subsolidus-postmagmatic cooling of magmas. The exchange mechanism is mainly diffusion-controlled. It is  相似文献   

Rapid Variscan exhumation and the role of magma in core complex formation: southern Brittany metamorphic belt, France   总被引：6，自引：0，他引：6  

MICHAEL BROWN  R. DAVID DALLMEYER 《Journal of Metamorphic Geology》1996,14(3):361-379

ABSTRACT The high-grade migmatitic core to the southern Brittany metamorphic belt has mineralogical and textural features that suggest high-temperature decompression. The chronology of this decompression and subsequent cooling history have been constrained with ⁴⁰Ar/³⁹ Ar ages determined for multigrain concentrates of hornblende and muscovite prepared from amphibolite and late-orogenic granite sheets within the migmatitic core, and from amphibolite of the structurally overlying unit. Three hornblende concentrates yield plateau isotope correlation ages of c. 303–298 Ma. Two muscovite concentrates record well-defined plateau ages of c. 306–305 Ma. These ages are geologically significant and date the last cooling through temperatures required for intracrystalline retention of radiogenic argon. The concordancy of the hornblende and muscovite ages suggest rapid post-metamorphic cooling. Extant geochronology and the new ⁴⁰Ar/³⁹Ar data suggest a minimum time-integrated average cooling rate between c. 725 °C and c. 125 °C of c. 14 ± 4°C Ma^-1, although below 600 °C the data permit an infinitely fast rate of cooling. Mineral assemblages and reaction textures in diatexite migmatites suggest c. 4 kbar decompression at 800–750 °C. This must have pre-dated the rapid cooling. Emplacement of two-mica granites into the metamorphic belt occurred between 345 and 300 Ma. The youngest plutons were emplaced synkinematically along shallow-dipping normal faults interpreted to be reactivated Eo-Variscan thrusts. A penetrative, west-plunging stretching lineation developed in these granites suggests that extension was orogen-parallel. Extension was probably related to regional uplift and gravitational collapse of thermally weakened crust during constrictional (escape) tectonics in this narrow part of the Variscan orogen. This followed slab breakoff during the terminal stages of convergence between Gondwana and Laurasia; detachment may have been consequent upon a change in kinematics leading to dextral displacement within the orogen. Dextral ductile strike-slip displacement was concentrated in granites emplaced synkinematically along the South Armorican Shear Zone. Rapid cooling is interpreted to have resulted from tectonic unroofing with emplacement of granite along decollement surfaces. The high-grade migmatitic core of the southern Brittany metamorphic belt represents a type of metamorphic core complex formed during orogen-parallel extensional unroofing and regional-scale ductile flow.  相似文献   

胶东昆嵛山花岗岩的特征、成因及其与金矿的关系   总被引：22，自引：0，他引：22       下载免费PDF全文

徐洪林  张德全  孙桂英 《岩石矿物学杂志》1997,16(2):131-143

昆嵛山花岗岩是牟平—乳山金矿成矿带的围岩，在其成因和定位时代上长期存在争议。本文对岩体地质和地球化学特征进行了系统研究，并就岩体成因及其与金矿的关系进行了讨论。作者认为，昆嵛山花岗岩是在中生代由岩浆缓慢冷凝结晶形成的大型复式岩基，并非交代成因。它由垛崮顶片麻状花岗闪长岩（１４７Ｍａ）、八门邹家斑状花岗闪长岩（１３５Ｍａ）、瓦善—水道弱片麻状二长花岗岩及五爪山片麻状含榴二长花岗岩（１２０Ｍａ）组成，成分具贫铝富碱的特点。岩浆来源于中下地壳中酸性变质火山岩系部分熔融形成的岩浆，其形成温度为６５０—７５０℃。岩体经历了韧性和脆性变形作用，不同方向的片麻状构造是岩浆结晶期韧性变形作用的结果。脆性变形形成的断裂和破碎带是本区主要的导矿和容矿构造。花岗岩定位、韧和脆性变形作用与金矿成矿作用有十分密切的关系  相似文献   

杨溪岩体中黑云母的特征及其地质意义   总被引：8，自引：0，他引：8       下载免费PDF全文

彭花明 《岩石矿物学杂志》1997,16(3):271-281

杨溪岩体黑云母为１Ｍ型的铁质黑云母，其特征说明岩体为壳源改造型花岗岩，但有幔源物质混入。离铌钽矿化点较近的黑云母表现出明显富铝、多锰、贫镁、少硅、少钛的特点。离白钨矿矿区较近的黑云母与远离矿区的黑云母在特征上差别不大，说明杨溪岩体黑云母的特征变化对成矿影响不大，但岩浆活动是重要的成矿因素之一。  相似文献   

扬子地台西缘富碱花岗斑岩特征及成因探讨   总被引：12，自引：2，他引：12  

胡祥昭  黄震 《大地构造与成矿学》1997,21(2):173-180

本详细研究了扬子地台西缘富碱花花岗斑岩的岩石学、矿物学、稀土元素地球化学和Ｓｒ、Ｓ、Ｐｂ同位素的特征，指出富碱花岗斑岩侵入年代新，同其同位素年龄范围为３５－５２Ｍａ，属于喜马拉雅期产物，岩石主要成分钾长石（３５％－４５％）、斜长石（１５％±）、黑云母（１０％±）和角闪石（５％±）。  相似文献   

华北地台主要花岗岩-绿岩带含金丰度值的研究     

李俊建  沈保丰 《华北地质》1997,(4)

近十余年来，在华北地台太古宙花岗岩－绿岩带金矿的研究中，获取了许多有关地层、岩石金丰度值的资料。早期获取的资料因化验分析方法灵敏度不高且样品中常常包含矿化、蚀变和构造破碎的岩石等原因而使其金丰度值偏高。最新的数据采用了高灵敏度化验分析方法且剔除了矿化、蚀变和破碎的岩石样品，计算出的金丰度值均明显低于或接近于地壳金丰度值。结合其它研究成果，提出绿岩带有关金矿矿源是多源的（变质的、岩浆的），甚至是深源的（下地壳或上地幔）认识。  相似文献   

江南隆起东端伸展构造的识别及其意义   总被引：2，自引：0，他引：2  

张开均 《安徽地质》1997,(2)

通过对屯溪流塘盆地典型伸展堆叠构造几何学和运动学的解剖，以及对其它几个伸展构造实例的分析，指出伸展构造在江南隆起的存在，它们的形成主要是重力作用的产物，遍及中、新生代。这种特征构造的解剖有助于深化认识江南隆起的构造特点和演化历史。  相似文献   

吕梁山北段变质岩系变形分解作用初探   总被引：2，自引：0，他引：2  

米广尧  苗培森 《华北地质矿产杂志》1997,12(2):167-175

吕梁山北段变岩系中，变形分解现象从宏观到微观的各级尺度上均有表现。平面上强弱变形带（域）常呈网结状形态产出，剖面上随深度的加深，强弱变形带（域）互为消长。在变形分解作用一，角闪石转化为黑云母、绿泥石、斜长石牌号降低。固流限较低的矿物发生溶解，或充填缍裂隙形成同构造分泌结晶脉，或在一定条件下形成变斑晶，致使岩石的结构构造由块状向片麻状、片状转化。Ｍｇ、Ｆｅ、Ｔｉ、Ｐ、Ｋ、Ｒｂ增高，Ｓｉ、Ｎａ、Ｓｒ降  相似文献