【作者】 李生喜；

【导师】 高军平；

【作者基本信息】 兰州大学 ， 地球化学， 2010， 硕士

【摘要】 青藏高原是中国最大和最高的高原,具有全球独特的地域单元,它的形成隆升是新生代地质史上的重大事件,其演化发展对中业地质地貌的演变乃至全球环境变化有着巨大的影响。尽管在国内外广大地学工作者的不懈努力下,青藏高原研究已取得了骄人的成就,但是,迄今为止,对青藏高原隆升的时间、过程、幅度和形式以及高原隆升的资源环境效应等问题,尚未取得一致的认识。柴达木盆地是以印度—欧亚板块碰撞后南北向挤压应力为动力学背景的高原内陆盆地,大地构造位置处于亚洲中轴构造域和特提斯—喜马拉雅构造域的结合部位,沉积了巨厚的新生代地层,这些盆地沉积物以及提供沉积物的周边山地基岩完整地保存了高原隆升和盆地演化的详细信息。本文以热年代学为理论基础,在总结分析柴北缘区域地质演化的前提下,对采自柴达木盆地北缘不同时代的样品进行磷灰石裂变径迹测试。对径迹长度分布分析发现,柴北缘基岩自燕山早期以来一直处于逐渐抬升状态；通过对年龄数据信息的详细统计以及结合磷灰石的表观年龄分布,提出柴达木盆地自早侏罗纪以来,经历了五期热构造事件,它们年龄依次为(186±10)Ma、(139±8)Ma、(112±7.5)Ma、(89±6.67)Ma、(53.25±5.25)Ma。依据裂变径迹年龄在空间的展布,得出柴北缘冲断褶皱带具有后展式构造特征,为柴北缘的盆山耦合机制研究提供了充分的证据,同时指出在近东西方向上抬升冷却具有明显差异性。经对所有样品的热史模拟,不仅表证了前述的热构造事件,而且推断出柴北缘的后展式冲断褶皱带构造可能形成于早喜山期,但进入第四纪后,柴北缘总体快速抬升冷却,其抬升速率介于731-12m/Ma之间。更多还原

【Abstract】 Qinghai-Tibet Plateau is the largest and topmost plateau in China, with a global unique geographical unit of the world, and it is a great event in global geological pro-cesses that the formation and uplift of the Plateau in Cenozoic. The evolution of the Plateau has a huge impact for the geological-topographic evolvement of Central Asia or even global environmental change. Although study of the Qinghai-Tibet Plateau has acquired remarkable achievements by geological workers all over the world had worked hard for last decades, so far, the time, process, range and form of the Plateau uplift and its resources-environment’s effects etc have not yet obtained the consistent know. The Qaidam Basin is an inland basin formed by the north-south di- rection co-mpressive stress which caused by the collision of India and Eurasia plate, it located between Asia axial and Tethyan-Himalayan tectonic domain structurally, has depo-sited huge thick strata of Cenozoic, the strata and bedrock around the mountains whi-ch had supplied sediments to the Basin was reserved detailed information about the Plateau uplift and the Basin evolution.In this paper, according to principle of thermochronology, combined with the re-gional geological evolution of Northern margin of Qaidam Basin(NMQB), had colle-cted rock samples which from different times and places of the margin to tests apatite fission-track data. The analysis of fission-track length distribution showed that bedro-cks of NMQB has been gradually uplifting since the early Yanshan; By detailed stat-istic of AFT ages and distribution of AFT apparent age, we proposed the NMQB has experienced five thermo-tectonic events since the early Jurassic, their ages were (186±10) Ma, (139±8) Ma, (112±7.5) Ma, (89±6.67) Ma,and (53.25±5.25) Ma, respectively.Spatial distribution of AFT ages show thrust-fold belt of NMQB has the overstep propagation, and that provides reliable evidence for the basin-mountain cou-pling mechanism of NMQB, also pointed out that it has a significant different uplifti-ng-cooling from the east to west. By thermal history modeling of all AFT data, we are not only proved NMQB had experienced five Thermo-tectonic events, but also infer the thrust-fold belt of overstep propagation in NMQB may be formed in the early Hi-malayan, but NMQB rapid uplift and cool since Quaternary, its uplift rate is about 731-12m/Ma.更多还原