摘要:本文系统分析了研究区及周边沉积演化历史、深大断裂特征、晚三叠世主要构造事件、现今贺兰山周围地层分布情况，结合地震资料、重磁资料以及最新的物源研究成果，对贺兰山晚三叠世盆地属性做了系统总结。重点探讨了研究区深大断裂的形成及后期多期次活化过程，研究区不同演化阶段的沉积特点以及晚三叠世早期、末期构造事件的表现特征。研究认为贺兰山晚三叠世盆地形成于块体相互作用下的张性环境，主要为叠加在早古生代贺兰山裂谷（凹陷？）盆地和晚古生代稳定盆地之上的拉张断陷盆地，断层系统表现为“地堑式”，盆地形态近似于“梭型”，西部塔尔岭—白芨芨沟一带断陷最为强烈，断距最大，北东延伸至正谊关断裂北部、南部延伸至炭井沟以南一带，整个断裂呈弧形，且两端断距逐渐减少。其中汝箕沟—香棒子沟断层为该时期深大断裂带的浅部延伸，东部以大水沟—鬼头沟断裂和现今银川地堑底部某断裂共同组成该地堑的断层系统。
关键词: 贺兰山/
晚三叠世/
深大断裂/
盆地属性
Abstract:The sedimentary evolution of the studied area and its related areas has been analyzed via the seismic analysis, gravity, magnetic data and the latest research based on the provenance, including the characteristics of the deeply large faults, the major tectonic events of the Late Triassic and the distribution of strata around the Helan Moutains. The formation of deep faults in the studied area has been influenced by multi-phased interaction after the later period. The main characteristics of studied sediment in different epochs has been depicted here, involving the changes presented in the early and the end of the Late Triassic. The sag rift formed from the Early Paleozoic and the extended basin produced in the stable basin from the Late Paleozoic suggests that the main basin in Helan Moutains formed by the largely extensional depression which has been interacted among the blocks from the Late Triassic. The whole fault system is characterized by the ‘Mantle Mode’ which performs a shuttle-like shape. The structure of the western Taerling-Baijijigou fault shows the most flexibility which is also with the longest depression distance. The Taerling-Baijijigou fault is shaped like a large curve which extends to the west of Zhengyiguan falut in the northeast direction and extends to the Tanjinggou area in the south direction, reducing gradually to the ends. The co-occurred Rujigou-Xiangbangzigou fault presents a shallow extension of the mainly deep depression which is fused by the west of Dashuigou-Guitougou fault and a present unnamed fault at the bottom of Yichuan mantle.
Key words:Helan Mountains/
Late Triassic/
Deep faults/
Basin characteristics
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