柴西西岔沟剖面新生界碎屑锆石裂变径迹年龄对物源区构造活动的制约  

Constraints of tectonic evolution in provenance from detrital zircon fission-track data of Cenozoic strata of Xichagou district in western Qaidam Basin

作　　者：高军平[1] 李生喜[1] 戴霜[1] 李艾银[1] 彭杨宏[1] 

机构地区：[1]兰州大学西部环境教育部重点实验室,兰州730000

出　　处：《兰州大学学报（自然科学版）》2009年第3期1-7,共7页Journal of Lanzhou University(Natural Sciences)

基　　金：国家重点基础研究发展计划(973计划)项目(2005CB422001);教育部科学研究重大项目(306016);国家自然科学基金委青年科学家群体研究项目(40421101)

摘　　要：对柴西西岔沟新生界碎屑锆石裂变径迹年龄的研究表明:沉积源区主要为遭受150～290 Ma热事件影响的阿尔金山带,在晚近纪晚期以后有古近系的加入;同时记录的发生于源区的构造热事件最早为海西早期,在海西中期有所加强,海西晚期之后至燕山早期为主要时期,尤以海西末-印支期最为鼎盛;在整个新生代源区抬升渐强、剥蚀加快。阿尔金断裂在8 Ma活动加强,在新近纪晚期表现为活动加剧,同名山系快速隆升,成为柴西主要物源区。柴西地区沉积源区在相对固定的态势下,也有一定分异性,即物源区的变更。古阿尔金断裂是存在的,随青藏高原内不同块体依次向北拼贴,且阿尔金断裂具有多阶段活动的特点。The dating of the uplift and exhumation of the Altun mountain-belts, the northern boundary of Qinghai-Tibetan Plateau, is a foundamental issue for better understanding the provenance of the sediments in western Qaidam Basin. Using zircon fission-track we determined that the provenance is the orogen located in the western boundary of Qaidam Basin, which suffered from an about 150-290 Ma thermo-event; but palaeogene strata provided some sediments in the late neogene and ever since. The region providing sediments was firstly affected by an early-middle hercynian movement and the area undergoing the late hercynian to early Yanshanian movement is the main provenance. This is the most important source region which sufferd from later Hercynian to Indonisian movement especially. Uplift and denudation of the region was rapid in the cenozoic. Altun tagh fault （ATF） moved strongly at 8 Ma, then did so more strongly in the late neogene. Altun mountain belt uplifted rapidly and provided for sediments in western Qaidam Basin. Palaeo altun tagh fault occurred at that time. It was suggested there were multi-stage activities of ATF. The provenance and exhumation of the western Qaidam Basin were relatively stable in the cenozoic, but it was shown that the provenance changed synchronously.

关 键 词：锆石 裂变径迹 构造热事件 物源 柴达木盆地 

分 类 号：P597[天文地球—地球化学] P542[天文地球—地质学]