塔里木盆地北部中下奥陶统碳酸盐陆棚—盆地的层序地层分析

ANALYSIS OF TYPICAL CARBONATE SEQUENCES IN NORTHERN TALIMU BASIN

露头剖面的层序地层分析是层序地层研究的重要内容之一，本文对塔里木盆地北部一组发育在不同沉积背景上的碳醚岩陆棚—盆地的层序，进行了详细的沉积学、古生物学和地球化学研究，系统探讨了层序中各体系域、层序界面和密集段的主要特征，通过对典型层序的分析发现，对于碳酸盐岩，特征明显，体系域易于识别的层序，发育在较浅水的背景上，在深水条件下，体系域较难识别，由此可以推论得到，在很深水的盆地中，多个层序可完全复合成复合层序，密集段可形成复合密集段，这时各个层序将可能无法区分。所能识别出的符合物理学标准的层序，将与更高级别的海平面变化相对应。

The analysis of outcrop sequences is one of the most important contents is sequencestratigraphy,The detailed studies of sedimentology,palaeontology and geochemistry have beenmade about a set of carbonate sequences developing different depositional settings in northernTalimu Basin. The main characteristics of system tracts,sequence boundaries and condensed sec-tions of the seq uences have been discussed systematically.On the basis of above analyses,it hasbeen discovered that the typical carbonate sequence develoloped on the shallow depositional set-tings,and under the conditions of deep water,sequences and their system tracts would be diffi-cult to be distinguished.So we can get the conclusion that several sequences may merge into oneto form composite sequence,their condensed sections will combine composite One,and the se-quences will not be able to be divided in the deep basin environments.The sequences that can bedistinguished and accord with physical criterion in the deep environments will correspond to higherorder sea-level changes.