青藏高原西南部南北向构造研究的新见解  

The NS-trending structures in the southwestern part of the Qinghai-Xizang Plateau:New insights

作　　者：雍永源[1] 

机构地区：[1]成都地质矿产研究所,四川成都610081

出　　处：《沉积与特提斯地质》2012年第3期21-30,共10页Sedimentary Geology and Tethyan Geology

摘　　要：广泛分布在青藏高原西南部的南北向构造,是高原新生代陆内汇聚变形的重要组成部分。经过中外学者40余年研究,至今已取得许多重要进展并形成了一些共识,也存在若干分歧。作者对南北向构造研究及某些共识的不同意见是:①南北向构造不仅有伸展构造形迹,还有褶皱、逆断、叠加等挤压构造形迹;②不能用裂谷系代表所有的伸展构造,也不能用裂谷系、地堑系等伸展构造名称代表高原西南部的全部南北向构造形迹。建议采用"南北向构造"这一包容性强的中性名称;③南北向构造最早产生于始新世-渐新世;④首先产生南北向伸展构造的是藏北羌塘-青南地区而非喜马拉雅地区;⑤大致在渐新世末-中新世初,青藏高原曾出现过一次短暂的东西挤压应力场,生成了各式挤压构造变形形迹。本文的新见解既丰富了南北向构造的成份与内涵,又可以此将南北向构造划分为早期(E2-3)伸展、中期(E3末-N1初)挤压、晚期(中新世及以后)再伸展3个发生、发展期。Nunerous studies conducted in the southwestern part of the Qinghai-Xizang Plateau in the last decades have revealed that there has been considerable progress but still debate concerning the NS-trending structures in this vast area. These NS-trending structures represent an important part of the Cenozoic intracontinental convergent deformation on the Plateau. Some aspects of views from the author in the present paper are suggested as follows. （ 1 ） The NS-trending structures consist of not only the extensional structures but also the compressional structures such as folds, overthrust faults and superimposed structures. （2） The terminology rift systems can＇ t be applied to represent all of the extensional structures, and the rift systems and graben systems also can＇ t represent all of the NS-trending structural features. Instead, the NS-trending structures are herein suggested. （3）The NS-trending structures in the study area were initiated during the Eocene to the Oligocene. （4）The NS-trending extensional structures were initiated in the northern Xizang to southern Qinghai zone rather than in the Himalayas. （5）A phase of temporary EW-trending compressional stress field once occurred on the Plateau during the latest Oligocene to the earliest Miocene, and resulted in the formation of various compressional structures. The NS-trending structures outlined above show a long and complex history, with early initiation and development spanning three phases of extension during the middle and late Eogene,compression during the latest Eogene to the earliest Neogene, and re- extension during the Miocene or later.

关 键 词：青藏高原 南北向构造 新见解 

分 类 号：P542.3[天文地球—构造地质学]