Depositional Sequence and Filling Response Characteristics ofSilurian in Tarim Basin
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摘要: 塔里木盆地志留系是由角度不整合面所限定的一个区域性（二级）的沉积层序，其内可划分出5个三级沉积层序。总体上显示一个从水进到水退的沉积旋回，可识别出曲流河三角洲—辫状河三角洲、滨外陆棚及较深水盆地、无障壁碎屑滨岸—无障壁碎屑潮坪沉积体系组合，它们代表了二级沉积层序中相对低位、海侵和高位的3个沉积体系组合。研究区构造、沉积、古生物和古气候资料表明，层序1底界面和层序5顶界面是塔里木周缘板块构造挤压、盆地隆升作用的结果；层序2底界面是周缘板块强烈挤压、盆地挠曲下降作用结果，同期全球海平面快速上升；层序3、层序4和层序5的底界面是在构造作用稳定、全球海平面下降背景之上由相对海平面次一级旋回变化形成的，是古气候变化、沉积物供给及构造沉降共同作用的结果。Abstract: Silurian in Tarim Basin，bounded at the top and base by widely spread regional unconformities，can be divided into 1 secondorder sequence and 5 thirdorder sequences. Three kinds of depositional system assemblages，which represent lowstand systems tract，transgressive systems tract，and highstand systems of the secondorder sequence，are identified in Silurian of Tarim Basin, namely, assemblage of meandering river delta and braided river delta depositional systems，assemblage of offshore and slightly deepwater basin depositional systems, and assemblage of clastic coastal depositional system with no barriers and clastic tidal depositional system with no barriers. Based on the integrated analysis of data of tectonics，sedimentology，palaeontology and palaeoclimatology，the base boundary of sequence 1 and top boundary of sequence 5 are thought to be originated from the pressure of peripheral plates and uplift of basin base. The bottom boundary of sequence 2 belongs to tectonically compressed unconformity that originates from the pressure of plates and decline of basin base. The bottom boundary of sequence 3, sequence 4 and sequence 5 results from integrated effect of change of climate, sediment source and tectonic activity under falling global eustacy.
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Key words:
- Silurian /
- depositional sequence /
- palaeoclimate /
- filling response /
- Tarim Basin
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