摘要
中新世以来 ,受青藏高原造山隆起产生的侧向推挤 ,滇西及邻区发生向南东的构造逸脱 ,红河断裂发生右行走滑运动 ,在漠沙、逸萨等断裂弯曲地段由于应力松弛发生下陷 ,形成小型走滑松弛盆地 ,其特征有别于拉分盆地。本文以漠沙盆地为例 ,通过砂岩薄片粒度分析及砂岩碎屑组分定量分析 ,综合野外及室内地质研究 ,对此类盆地的岩石学特征、沉积环境、物源和构造特征等进行了详细的研究 。
Trans releasing basin is a kind of trans tensional ones, and the Mosha basin is taken as an example, controlled by the Neogene Red River fracture in west Yunnan. The dextral strike slipping might begin from late Miocene (10～7 Ma B.P.),during that time two trans releasing basins (Mosha and Yisa) occurred along the bend segments, filled by the lower half of Xiaolongtan Formation. From Early Pliocene (about 4.7 Ma B.P.), a superimposed trans downfaulted basin formed, and the upper half of Xiaolongtan Formation distributed widely in the Red River valley. The field observation and grain size analyses of sandstone indicate the lower half of the formation in the Mosha basin being a set of alluvialfan deposits, fluvial deposits, delta deposits as well as lacustrine sediments. The spatial distributions of sediments with varied facies comprehend the west boundary being the Red River fault, and the east boundary a depressional one complicated by two sub order shearing faults. The pebble study showed the main provenance was to the west of the basin where outcropped the metamorphic rocks of Ailaoshan Group; in addition, some clasts were from the Upper Triassic and Lower Jurassic to the east of the basin. Due to further collision of the India and Eurasia plates and uplifting of the Qinghai Tibet plateau, the area of SW China tectonically escaped towards the southeast, with the Red River fault being the west boundary from Late Miocene. This is tectonic setting of the Neogene basins along the Red River fault. In Late Pliocene (about 3 Ma B.P.), these basins closed. To sum up, a comparison between trans releasing and pull apart basins is represented.
出处
《地质科学》
CAS
CSCD
北大核心
2001年第3期370-379,共10页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金重点项目 (编号 :4 9732 1 0 0 )成果之一
