南海珠江深水扇系统的层序地层学研究

Sequence stratigraphy of Pearl River Deep-water Fan System in the South China Sea

位于古珠江大河及其浅海陆架富砂珠江三角洲下方的陆坡深水区白云凹陷是沉积大型深水扇的有利地域,宏观认识的进展指导了白云深水陆坡区系统的层序地层学研究,并因此发现了多层序叠置的南海珠江深水扇系统,使其成为具有油气勘探潜力的新领域。南海珠江深水扇系统的层序地层学研究包含了以下关键内涵层序地层学解释中在承认各种资料的分辨率、多解性和局限性的同时,强调多学科资料的综合应用、相互印证,强调周期性海平面变化对沉积的控制作用研究,强调地震反射相位等时界面确认的有效性,强调层序界面的反复确认,强调生物地层时代、相对海平面、全球海平面与层序界面的响应研究,强调层序格架内各沉积体的相互响应关系研究等。层序地层格架的建立导致了珠江深水扇系统的发现,揭示了珠江大河流域、陆架区大型珠江三角洲系统与陆坡区珠江深水扇系统的耦合关系,揭示了珠江深水扇与海平面变化的响应关系,揭示了珠江深水扇与古地理的响应关系。珠江深水扇系统的发现有力地推动了南海陆坡深水区的油气勘探。

The Baiyun Sag, located in the deep-water continental slope region and on the down dip side of the paleo-Pearl River and the large sand-rich Pearl River delta in shallow continental shelf, is a favorable area for developing large-scale deep-water fan system. The study of sequence stratigraphy of the deep-water slope area aided by regional geological research led to the discovery of the Pearl River Deep-water Fan System with its overlapping multi-sequences, which makes the Baiyun Sag a new prospective area for petroleum exploration. Apart from the resolution of different data, multiple solutions and limitations in the interpretation of sequence stratigraphy, the study of the Pearl River Deep-water Fan System emphasizes the following research aspects： （1） the comprehensive application and mutual authentication of data from different disciplines; （2） the control of periodic sea-level change on the depositional systems; （3） validity of the identification of the isochronic horizons from seismic reflection and the identification of sequence boundary; （4） the response of the sequence boundary to biostratigraphy, relative sea-level change and global eustacy; and the response correlation between different sedimentary bodies in a sequence-stratigraphic framework. The buildup of the sequence-stratigraphic framework leads to the discovery of the Pearl River Deep-water Fan System. It reveals the coupling relationship among the Pearl River drainage area, the large-scale Pearl River delta on the continental shelf and the Pearl River Deep-water Fan System on the continental slope; as well as the response relationship between the Pearl River Deep-water Fan System and the sea-level changes; and the correlation between deep-water fans and paleogeography. The discovery of the Pearl River Deep-water Fan System greatly promotes petroleum exploration in the deep-water slope area of the South China Sea.