塔里木盆地柯坪地区奥陶系层序地层研究

Ordovician sequence stratigraphy of Keping area,northwest Tarim Basin

以露头层序地层学和沉积学为指导,对塔里木盆地西北缘柯坪地区奥陶系3个剖面进行了深入研究,建立了柯坪地区奥陶系层序地层格架。柯坪地区奥陶系由6个三级层序组成,横向对比表明四石厂剖面发育最完整,同古四布隆和苏巴什剖面有地层缺失,只能识别出下部3个三级层序。碳酸盐岩磁化率测量结果表明,磁化率的变化趋势与相对海平面升降曲线之间呈负相关,并且与层序界面、层序内部各体系域之间有着较好的对应关系,可以作为划分层序的一个辅助性的定量化指标。

The Ordovician sequence stratigraphic framework has been erected in this paper on the basis of the investigation of outcrop sequence stratigraphy and sedimentology along three sections in Keping area, northwest Tarim Basin. The Ordovician strata can be divided into six third-grade sequences. Correlations shows all these six sequences can be recognized in the Sishichang section, while only the lower three ones are developed in the Subashi and Tongusibulong section. Carbonate magnetic susceptibility is negatively related to the relative sea level change, while its curve can reflect the sequence boundaries and system tracts of the third-grade sequences respectively. The results obtained by the authors indicate that carbonate magnetic susceptibility can be used as a quantitative index to assist the division of stratigraphic sequence.