珠江口盆地惠州凹陷古近纪幕式裂陷特征

Features of paleogene episodic rifting in Huizhou fault depression in the Pearl River Mouth basin

近年来裂谷盆地研究的一个重要进展就是认识到了裂谷过程的多幕性。通过对裂陷期内的区域性角度不整合、超覆、地层大量缺失以及三级层序空间展布的旋回性分析,论证了珠江口盆地惠州凹陷古近纪是典型的幕式裂陷,其具有"两幕裂陷构造格架未发生变化"的独特特征。在此基础上,对惠州古近纪幕式裂陷的特点及其动力学含义进行了分析。研究表明:惠州凹陷古近纪具有典型的幕式裂陷特征;构造格局未发生变化的幕式裂陷可能反映了板块及深部动力学作用的幕式性;推测与裂谷盆地相关的岩石圈均衡调整可能为幕式的非均质伸展过程。

The recognition of episodic nature of rifting is considered as a major progress in research of rifted basins in recent years. Based on the analysis of the regional angular unconformities,stratigraphic overlap,absence of many formations and the cyclicity of third-order sequences,it is believed that the Huizhou fault depression in the Pearl River Mouth basin experienced typical episodic rifting in Paleogene and a unique phenomenon that the tectonic framework kept unchanged in two episodes of rifting was occurred. The features and dynamic implications of the Paleogene episodic rifting are also discussed. The following understandings are obtained:a. Huizhou fault depression is a typical episodic rift in Paleogene; b. episodic rifting without change of tectonic framework may reflect the episodic nature of plate and deep dynamics; c. rifted basin-related lithospheric isostatic adjustment is predicted to be heterogeneous episodic stretching.