| 论大别造山带中“罗田片麻岩杂岩”的构造属性 |
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| 引用本文： | 张勇.论大别造山带中“罗田片麻岩杂岩”的构造属性[J].安徽地质,1996(2). |
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| 作者姓名： | 张勇 |
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| 作者单位： | 安徽省地质科学研究所 |
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| 摘 要： | 罗田片麻岩杂岩位于大别造山带腹地，东、西大别变质带之间，面积约６０００ｋｍ２。主要由一套花岗片麻岩系组成。它们经历过早期高角闪岩相至麻粒岩相变质和晚期低角闪岩相叠加变质。该杂岩的原始建造以古老变质变形侵入体为主，与其周边构造变质单元的原始建造迥然不同，后者皆为沉积型或火山－沉积型原始建造。罗田片麻岩杂岩与其周边环境的地质特征不一致，是个造山带规模的外来变质地体。其下存在广泛的低密度岩层，相当于混合岩化或花岗岩化的硅铝质岩系。罗田片麻岩杂岩是华南、华北陆块碰撞期间，可能曾经存在的古岛弧深成岩系发生深变质强变形，并在仰冲机制作用下，于 地壳深层次拼贴到高压／超高压碰撞混杂岩之上的，具有推覆体属性的构造岩片。
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| 关 键 词： | 罗田片麻岩杂岩，推覆岩片，变质地体，大别造山带 |
ON THE TECTONIC AITRIBUTE OF THE LUOTIAN GNEISSIC COMPLEX IN THE DABIE OROGEN |
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| Zhang Yong.ON THE TECTONIC AITRIBUTE OF THE LUOTIAN GNEISSIC COMPLEX IN THE DABIE OROGEN[J].Geology of Anhui,1996(2). |
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| Authors: | Zhang Yong |
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| Institution: | Anhui Institute of Geology Hefei 230001 |
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| Abstract: | Dabieshan mountains are a geologically complicated collisional orogen,in which there exist many enigmatic phenomena needing detailed investigation. One of these phenomena is why Luotian gneissic complex is exposed in the EW extending HP/UHP collsional metamorphic rock zone and the latter transected by the gneissic complex. In the past, the Luotian gneissic complex was thought to be the kernel of ancient Dabieshan crystalline massif or grey gneiss dome. Luotian gneissic complex is dominatd by TTG gneisses which have undergone an earlier high grade amphibolite-granulite facies etamorphism and later low amphibolite facies metamorphism. The original formation of the Luotian gmeissic complex is different from the sedimentaty ovolcanic sedimentary one for the tectonometanorphic units around it No HP/UHP metamorphic blocks occurred in the TTG gneiss region. Therfore, Luotian gneissic complex is a roreign metamorphic terrain in orogen scale consistent with its surroundings in geological characieristics. Geophysically, under the Luotian gneissic complex, there exist low-density rocks corresponding to the granitized Hongan group which constitute negative strip producing low density formation.Luotian gneissic complex is formed by deep metamorphism and deformation of ancient arc TTG Plutons in the southrn margin of North China plate during CollSion, and then put upon to the HP/UHP collsional melange by obductional mechanism. It has an attribute of nappe. It is exhumed by later extensional unroofing, lifting and natural erosion. |
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| Keywords: | Luotian gneissic complex nappe blocks tectonometamorphic units Dabie orogen |
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