摘要
大型河流是陆源碎屑物质搬运入海、入盆的主要方式,对全球地球化学循环起到了重要的作用。青藏高原是东亚和南亚大型河流的主要发源地,来源于这些河流的碎屑沉积物,不仅提供了源区重要的地质演化信息,同时还记录了河流本身的演化发育情况。碎屑矿物(锆石、磷灰石等)低温热年代学方法可对河流物源区进行限定,建立其源-汇沉积体系;还可以结合区域构造变形分析,获得河流潜在的物源区和高原地貌格局的形成年代,是近几年的研究热点。文中在近几年青藏高原周围的大型河流碎屑矿物和河谷基岩低温热年代学研究结果的基础上,对这些成果进行了总结和梳理。提出在进行河流碎屑矿物低温热年代学分析时,应在河流上游、中游和下游关键地点进行系统采样,同时加强主要支流的样品分析,才能给出更为详尽的区域热历史演化结果。在河谷基岩低温热年代学分析时,针对同一河流不同河段采用同一低温热年代学方法和不同河段同一研究位置采用多矿物(磷灰石、锆石等)低温热年代学分析方法,给出的河流下切时间序列更完整。并建议在青藏高原地区,将河谷基岩和河流碎屑矿物低温热年代学结果相结合,同时运用研究区内构造分析以及其他沉积学等研究结果,可提供研究区内详细的构造和河流自身演化过程。
The large river systems are the major transfer of continental masses to the ocean and basin,playing significant roles in global geochemical cycles. The Tibetan plateau is the birthplace of many huge rivers flowing through eastern and southern Asia,in which the fluvial deposits kept not only closely relate to the geological evolution information from the source areas,but also record the river itself building process. The low-temperature thermochronology method of detrital minerals( zircon and apatite,etc.) can be used to constrain the river's source areas,establishing its source-sink system. It can also combine regional tectonic deformation analysis to determine the potential source region of the river and the formation time of the plateau geomorphology,which is a focused issue in recent years. In this study,we have summarized the research results from the large rivers in the Tibetan plateau in recent years,suggesting that the low-temperature thermochronology analysis of the detrital minerals should be focused on the river's key locations in the upstream, midstream and downstream,respectively,combining the small tributaries analysis which can give a more detailed thermal evolution history in the whole drainage basin. On the conditions of the bedrock,it is shown that in the same river's different place we should use the same low-temperature thermochronology,while in different river's places we should take several low-temperature thermochronology methods( apatite and zircon,etc.) at a same position,so we get a complete time series related to the river incision. Combining the valley bedrock and detrital river minerals with the low-temperature thermalchronology on the Tibetan plateau,together with the chronology,structure analysis and other sedimentary studies,we can obtain detailed structures and river's evolution processes.
出处
《地震地质》
EI
CSCD
北大核心
2017年第6期1091-1110,共20页
Seismology and Geology
基金
国家自然科学基金(41702178)
山东省自然科学基金(ZR201702160378)
山东省高校创新基金(J17KA196)共同资助
关键词
青藏高原
低温热年代学
河流碎屑物
河谷基岩
Tibetan plateau
Low-temperature thermochronology
Detirtal river sediments
Valley bedrock
