| 摘要: |
| 笔者以冈底斯构造带内部近南北向发育的多桑地堑带为代表,简述了多桑地堑带构造的组成及基本构造特征。根据该地堑两侧断隆山的发育特征及磷灰石、锆石裂变径迹测年结果,推断地堑的断陷活动时期始于中新世,直至第四纪仍有活动,对上新世-第四纪沉积起明显的控制作用。多桑地堑带的形成可能为前期南北向受力不均而产生共轭X节理,后期南北向挤压的持续进行使地壳隆升,当隆升到达一定程度后造成重力塌陷及下地壳物质的侧向流动产生纵向拉张作用,此时前期形成的共轭X节理追踪并部分贯通,最终形成多桑地堑,而横向上的区域断裂则可能控制地堑各区段拉伸宽窄的变化和沉降的不均匀性。 |
| 关键词: 西藏 南北向构造带 地堑 正断层 成因机制 |
| DOI： |
| 附件 |
|
| 基金项目:四川省重点学科“构造地质学”建设基金(SZD0408) |
|
| Structural features and genetic mechanism of the Duosang graben in the Ngari area,Xizang |
| WANG Guan, TAO Xiao-feng |
| (College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China) |
| Abstract: |
| The present paper gives a detailed description of the structural features and genetic mechanism of the Duosang graben in the Ngari area,Xizang.Some speculations upon the genetic mechanism of the Duosang graben can be made on the basis of the structural development on both sides of the graben,and apatite and zircon fission-track age determinations.The rifting of the graben may be initiated during the Miocene,and continues to be active till the Quaternary.The N-S-trending compression of the Gangdise-Nyainqentanglha-Tengchong plate by the Indian plate resulted in the crustal uplifting first and then gravity sinking and lateral migration of the lower crustal matter.The E-W-trending extension led to the connection of some conjugate joints formed in the early stages and finally to the formation of the graben.The lateral regional faulting may have important effects on the width of the individual parts of the graben and inhomogeneity of subsidence. |
| Key words: Xizang N-S-trending structural zone graben normal fault genetic mechanism |
