歧口凹陷下第三系层序地层厚度特征

The Paleogene Sequence’s Character of the Thickness in the Qikou Sag

摘要: 依据最新研究资料，在歧口凹陷下第三系在层序格架控制下，可细分为三幕构造运动，仔细研究各层地层厚度及其幕式变化特征很有意义。从裂陷I幕到裂陷III幕、以及单个裂陷幕，构造活动性均呈逐渐减弱趋势。在深层基底右旋走滑断裂带和区域性伸展滑脱构造背景控制下，形成了歧口凹陷构造演化的总体格局。其总体呈现三带、四凹的构造格架，裂陷I幕处于扩张断陷阶段，裂陷II幕断陷活动趋于稳定的发展阶段，裂陷III幕断陷活动进一步减弱。

Abstract: Using the latest research data, in the sequence frame of lacunae in Qikou sag, there are three tec-tonic movements. Studying the thickness and the episodic character is meaningful. From the I la-cunae movement to the III lacunae movement, all single lacunae movement, and tectonic activity showed a trend of weakening in the deep basement right-lateral strike-slip fault zone and regional stretch decollement background under control. To form the overall pattern of tectonic evolution of Qikou sag, there are three zones, four general structural frameworks of concave. The I lacunae movement was expanding rift stage, the II lacunae movement was the stable stage, the III lacunae movement was further weakened.