摘要:
笔者建立了中扬子区寒武系层序地层格架,研究了中扬子区层序界面和体系域特点,分析了中扬子区层序样式的基本类型及其特征。共划分出2个二级层序、14个三级层序。寒武系下统划分了1个二级层序(SS3)、6个三级层序(SQ1-SQ6),平均延时约5.0Ma;体系域颜色普遍较深,泥质含量较高,是一套良好的烃源岩。寒武系中上统划分出1个二级层序(SS4)、8个三级层序(SQ7-SQ14),平均延时约2.9Ma;体系域颜色普遍较浅,云质含量较高,是一套良好的储集层。总体上H型样式为主,T型样式和TH型样式数量相当,反映寒武纪水体中等。二级层序体系域和三级层序体系域都表现出明显的南北向差异性。
Abstract:
The present paper deals with the Cambrian sequence stratigraphic framework, sequence boundaries, sequence patterns and systems tracts, in the middle Yangtze area. Two second-order sequences and fourteen third-order sequences have been distinguished, including:(1) one second-order sequence (SS3) and six third-order sequences (SQ1-SQ6) for the Lower Cambrian strata, with an average time duration of about 5.0 Ma. The systems tracts are generally dark-coloured, with higher mud contents, and thus may serve as excellent source rocks, and (2) one second-order sequence (SS4) and eight third-order sequences (SQ7-SQ14) for the Middle and Upper Cambrian strata, with an average time duration of about 2.9 Ma. The systems tracts are generally light-coloured, with higher dolomite contents, and thus may serve as excellent reservoir rocks. Collectively, the H-type patterns are dominated; the T-type and TH-type are almost identical, indicating a moderate water depth during the Cambrian. The NS-directed differences are manifested in both second- and third-order systems tracts.
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