| 川西南乡城——得荣地区的两种混杂岩及其构造意义 |
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| 引用本文： | 张之孟,金蒙.川西南乡城——得荣地区的两种混杂岩及其构造意义[J].地质科学,1979,14(3):205-214. |
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| 作者姓名： | 张之孟 金蒙 |
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| 作者单位： | 1. 中国地质科学院地质研究所;
2. 四川省地质局区域地质调查队 |
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| 摘 要： | 混杂岩或混杂堆积是一种奇特的地质现象。早在一个世纪以前,就有过描述和讨论。但是,直到板块构造提出之前,混杂岩没有得到合理的解释。就目前所知,我国台湾、祁连山、西秦岭、喜马拉雅山等地都有混杂岩分布。笔者通过近三年来在金沙江沿岸的地质填图及专题研究证实,四川乡城、得荣一带是混杂岩分布的又一典型地区。
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| 关 键 词： | , |
TWO KINDS OF MELANGE AND THEIR TECTONIC SIGNIFICANCE IN XIANGCHENG-DERONG AREA, SOUTHWESTERN SICHUAN |
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| Zhang Zhimeng,Jin Meng.TWO KINDS OF MELANGE AND THEIR TECTONIC SIGNIFICANCE IN XIANGCHENG-DERONG AREA, SOUTHWESTERN SICHUAN[J].Chinese Journal of Geology,1979,14(3):205-214. |
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| Authors: | Zhang Zhimeng Jin Meng |
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| Institution: | 1. Institute of Geology, Chinese Academy of Geological Sciences;
2. Geological Survey Team, Sichuan Geology Bureau |
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| Abstract: | Two kinds of melange extend meridionally parallel to the Jinsha River-Red River deep fracture and are distributed on its opposing sides. The region to the west of this deep fracture belongs to the Sankiang (i.e. Three-Rivers) eugeosynclinal fold belt, along which consolidation shifted from north toward south during the Noric stage. The Sungpan-Ganze eugeosynclinal fold belt extends over the region to the east of the deep fracture, and the eugeosyncline was developing until the end of Triassic. During the Triassic when two plates converged on which laid both eugeosynclines mentioned above, there occurred ophiolitie melange and olistostromic melange distributed on the under-thrusting (western) plate and on the overthrusting (eastern) plate respectively. It is considered that the so-called subduction zone here seems to be a deep fracture, namely, a plate suture line. The ophiolitic melange is characterized by the matrix of a suite of ophiolite containing many exotic blocks of various rocks, such as omphacite-eclogite, rodingite and fossiliferous limestone. However the matrix of the olistostromic melange dominated by argillaceous and arenaceous rocks containing fossils all younger in age than those in the exotic blocks. All the characteristics of the two kinds of melanges concerned herein may serve as a reference for elucidating their genesis. -It can be supposed that in the case of subduction of one plate beneath the other one the ophiolitic melange may be considered as a direct product under an intensive compressive stress acting in the upper part of the lithosphere. On the other hand, olistostromic melange can be regarded as the sedimentary unit formed under the horizontal stress in the water bodies nearby. After briefly reviewing previous works in this respect and preliminarily examining the studies on mechanism of melanges made by some geologists, the authors believe that the present concept as proposed here of the ophiolitic melange and the olistostromic melange could eventually get general approval, because it gives not only a reasonably genetic classification, but also a criterion easily grasped in field observations. It should also be noted that the results of research on melange reached by K. J. Hsu and A. Gansser are important contributions, but a certain amount of their revision still remains to be done. |
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