Deformation Structures of the Madao Gneiss in South Qinling:Structural Analysis,Geochronological Con

来源 :Acta Geologica Sinica(English Edition) | 被引量 : 0次 | 上传用户:justinhn
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
The tectonic evolution of South Qinling,which is a main part of the Qinling orogenic belt,is still in dispute and deformation history of South Qinling is poorly studied.In this paper,detailed structural,microstructural,quartz c-axis fabric analysis,and geochronology results for the Madao gneiss in South Qinling are presented to characterize the deformation history.Results show that rocks in the northern part(Tiefodian-Laozhanggou) experience general shearing and deform at relative low temperature.The shear sense generally is south to north.In contrast,rocks in the southern part(Laozhanggou-Panjiahe) are weakly sheared with pure shear features and evidence of hightemperature deformation.Based on the analyses,we conclude that there exist two distinct deformation geometries in the Madao gneiss and accordingly we can divide the deformation into two stages.The early stage is represented by regional shortening,while the late stage features northward thrust shearing and evidence shows that it was a progressive process between them.LA-ICP MS U-Pb dating of zircons from pre-deformational migmatite veins yields age of 198.5 ± 2.0 Ma.This result,in combination with the age of post-deformational granite,indicates that the northward thrust shearing of the Madao gneiss occurred in the Late Triassic.In view of these results and other reported data in South Qinling,we propose that deformation in Madao gneiss may result from the initial collision and subsequent northward accretion in Late Triassic. The tectonic evolution of South Qinling, which is a main part of the Qinling orogenic belt, is still in dispute and deformation history of South Qinling is poorly studied. This paper, detailed structural, microstructural, quartz c-axis fabric analysis, and geochronology results for the Madao gneiss in South Qinling are presented to characterize the deformation history. Results show that rocks in the northern part (Tiefodian-Laozhanggou) experience general shearing and deform at relative low temperature. The shear sense generally is south to north. In contrast , rocks in the southern part (Laozhanggou-Panjiahe) are weakly sheared with pure shear features and evidence of hightemperature deformation. Based on the analyzes, we conclude that there exist two distinct deformed geometries in the Madao gneiss and accordingly we can divide the deformation into two stages. the early stage is represented by regional shortening, while the late stage features northward thrust shearing and evidence that that was a progressive process between them. LA-ICP MS U-Pb dating of zircons from pre-deformational migmatite veins yield age of 198.5 ± 2.0 Ma. This result, in combination with the age of post-deformational granite, indicates that the northward thrust shearing of the Madao gneiss in the Late Triassic. In view of these results and other reported data in South Qinling, we propose that deformation in Madao gneiss may result from the initial collision and subsequent northward accretion in Late Triassic.
其他文献
导读:过程最美,它带给人们更多的体验,更多的启迪,更多的快乐。结果固然重要,但过程却必不可少。从最开始的那一刻起,让自己朝着积极正面的方向前进,就能体会到过程的美感。A
徐旭平教授1967年生,云南永胜人,1988年毕业于西南师范大学中文系(现西南大学),同年分配到文山师专中文系任教,一直从事《中国古代文学》的教学与研究,兼上全校的公选课《唐
题目期页!题目期页10 11 2 34 集成功放也可出舰声 一一几款集成功放的制作工艺及比较·······~·······~·~·……10★★低档合并式功放改为杜比解码放大器·一
在体育课堂教学中,磨课是其重要的一项教学方式,体育教师专业的提高需要磨课,同时还需要磨学情、磨理念以及磨反思等多方位磨砺,磨课可以在很大程度上提高提月课堂教学质量。
川崎病(KD)于1967年由日本川崎富作首先报告,曾称为皮肤黏膜淋巴结综合征,是一种以全身血管炎为主要病理改变的急性发热出疹性疾病。约15%~20%未经治疗的患儿发生冠状动脉损
鸡西矿业集团公司张辰煤矿西三采区3
期刊
Q:Last year,I have interviewed with you here.So Iwonder what further development has been achieved for trade exchanges between China and Georgia.A:From the same
In order to combat the impacts brought about by the international economic crisis, since the beginning of 2009, the government has introduced the revitalization
塔里木油田碳酸盐岩油气藏勘探获得重大突破,日产原油3 000 t,这个新区块将诞生一座年产百万吨的大油田。塔里木盆地碳酸盐岩油气藏丰富,约占盆地油气资源总量的30%,是塔里木
祝余,一种生长在招摇山上的草,形状很像山韭,开青色小花。吃了这种草没有饥饿感。  打开薄薄的书,看到的是朴实的文字,但其中却藏纳着无以描述的魄力景象。屹立于西海岸边的招摇山,满眼尽是馥郁的桂树,石藏金玉,草长祝余,葱茏的景色中出没着奇特的怪兽。《山海经》便向世人开启了一个恢宏而盛大的世界。从南山到西山,再由北山换之东山,四境不仅将海内外连为一体,同时也远远与大荒之境勾连,一个密不可分、神奇莫测的世
期刊