摘要
湖泊作为陆地上相对独立的自然综合体,是大气圈、岩石圈、生物圈和陆地水体相互作用的联接点,是区域环境的镜子.青藏高原中部从班长错至怒江分布密集的构造湖群,其东部位于印度季风区边缘的西藏那曲错鄂湖,发育有巨厚的湖泊沉积物,是研究高原环境演化的理想材料.本文对采自西藏那曲地区错鄂湖盆中心钻孔近200 m、形成于2.8 Ma以来的湖泊沉积物中的沉积旋回进行了研究,并结合沉积岩性、粒度和孢粉组合等,分析了该地区2.8 Ma来的古地理环境演化过程.研究表明,2.8 Ma来错鄂沉积物揭示了10个沉积旋回的变化和3大古环境演化阶段(2.8～2.5 Ma,2.5～0.78 Ma,0.78～0 Ma)与8个次级环境波动过程.初步研究认为,错鄂地区的环境演化主要是由高原构造活动和气候波动共同作用下形成的.总体上,大的环境演替与构造运动有关,各旋回中的次级波动则与气候变化关系密切.
There are lots of lakes in Tibetan Plateau. Regarded as a relatively independent natural environmental system in the land, the lake is a link of such factors as the atmosphere, the lithosphere, the biosphere, and the land water, and can serve as a mirror of regional environment. The Co Ngoin Lake with thick lacustrine sediments in Naqu area, which is located on the margin of the Indian monsoon, is an enclosed faulted inland lake basin. The sediments make up a prefect record for the study of paleoenvironmental changes. In this paper, the sedimentary cycles of a 200 m-depth core taken from Co Ngoin Basin were analyzed. The sediments reflect ten sedimentary cycles in Core-hole CN. In combination with lithologic properties, grain sizes and pollen assemblages, this paper has discussed the history of paleoenvironment change in the last 2.8 Ma. The sedimentary records indicate that this region has experienced three strong paleoenvironmental evolution stages (2.8～2.5 Ma, 2.5～0.78 Ma, 0.78～0 Ma), namely three tectonic-climatic sedimentary cycles and eight sub-environmental changes processes or eight climatic sedimentary cycles. Studies show that the paleoenvironmental evolution in Co Ngoin catchment was controlled by tectonic movement and climate change. In general, the major environmental changes were largely controlled by stepwise uplift of the Tibetan Plateau, and the small changes overlapped on the large tectonic background were mainly controlled by the climatic changes.
出处
《地球学报》
EI
CAS
CSCD
北大核心
2006年第4期315-322,共8页
Acta Geoscientica Sinica
基金
国家重点基础研究发展规划项目(编号:G1998040810)
聊城大学科研基金资助
关键词
错鄂
第四纪
沉积旋回
环境演变
西藏高原
Co Ngoin Quaternary period sedimentary cycle environmental evolution Tibetan Plateau
