摘要
本文从宏观上阐述了成都盆地形成的地质背景;盆地基底地层的缺失与古地理环境演化特征。从青藏高原的隆起时间相应地讨论了四川盆地晚白垩世以来的发展历程。认为,成都盆地是龙门山脉与四川盆物分化解体的派生构造形迹;早期堆积于盆底的大邑砾岩的沉积特征和物源特性表明了一个新地质时代的开启;极其粗大的碎屑体现了新构造运动垂直升降振荡作用的特点;大邑砾岩为构造侵蚀碎屑物,是成都盆地第四纪松散堆积层的代表。之后,盆地一直继承此沉积特征而沉积了最大厚达540m的砾卵石层。
The Chengdu basin is located at the juncture of the Sichuan basin and theLongmen Mountains on the eastern margin of the western Sichuan plateau. Theformation and evolution of the basin were closely related to the uplift of theQinghai-Tibet plateau and the subsidence of the Sichuan basin. This paper discus-ses the geologic setting for the formation of the Chengdu basin and the evolution-ary feature of its paleogeographic environments. It is considered that the Cheng-du basin is the tectonic remains resulting from the disintegration of the LongmenMountains and Sichuan basin and that the early deposits--the Dayi conglomeratebed--belong to a post-tectonic piedmont alluvial--diluvial molasse formation, whichis notably different from pre--Quaternary deposits in lithology and structraldistribution. It is suggested that the Chengdu basin is the tectonic remains ofthe third phase of the Himalayan movement. This phase of the Himalayan move-ment laid the foundation for the Chengdu basin. The Dayi conglomerate was depos-ited as a result of energy balancc and compensation of this phase of orogen.Then the basin was sinking intermittently. From the beginning of the accumula-tion of the Dayi conglomerate to the Holocene, a maximum thickness of 540 mof coarse fragments (gravel and pebble layer) was accumulated in the basin. Sothe base of the Dayi conglomerate is defined as the lower boundary of the Qua-ternary tentatively.
出处
《地质论评》
CAS
CSCD
北大核心
1992年第2期149-156,共8页
Geological Review
关键词
古地理环境
成都盆地
地质
时代
Palaeogeographic environment
Quaternary tectonic movement
Quatemary Dayi conglomerate
