流体性质转换机制在重力流沉积体系分析中应用初探

自1950年Kuenen发表"浊流形成粒序层理"一文至今,深水重力流研究取得了长足发展。然而,目前很多学者不仅对浊流理论分歧很大,而且对浊流概念、术语的使用也有不同的观点,这严重制约了重力流的分类及重力流沉积体系的识别。本文在重力流沉积过程和流态研究的基础上,提出了基于"流体性质转换"理论的重力流沉积体系分析方法。研究认为,重力流在形成、发展和消亡过程中不仅存在多个流体阶段,而且存在着多种流态之间的转换。这种流体发育的最终阶段特征决定了重力流沉积体系的形态与类别,而流态共存与转换的特性造成了深水紊流成因的浊积岩与其他流体成因的岩相共存的沉积特征。根据这一理论对牵引流—碎屑流成因的扇三角洲体系、浊流成因的近岸水下扇体系和碎屑流成因的斜坡裙体系进行成因分析与特征对比,阐述了"流体性质转换"理论在沉积体系识别中的作用。

Preliminary Study on Gravity Flow Depositional System Based on Fluid Properties Conversion Theory

Until the publication of Turbidity Currents as a Cause of Graded Bedding written by Kuenen in 1950, the gravity flow theory has made a great development. However, nowadays some geologists not only argue about the turbidity theory, but also have some problems in using concept and terminology of turbidity current. According to sedimentary process of gravity flow and fluid properties, this paper raises an analytical method of gravity flow depositional system based on fluid properties conversion theory. There are several fluid processes of the formation, development and extinction of gravity flow, including multiple conversions between different fluid properties. The final conversion results determine the morphology and category of gravity flow depositional system. At the same time, the complicated fluid conversion results the sedimentary characteristics that turbidities caused by turbidity current coexist the other lithofacies caused by other currents. According to this theory, we analyze the origin and sedimentary characteristics of fan delta caused by tractive-debris flow, Nearshore subaqueous fan caused by turbidity current and slope apron caused by debris flow, and discuss the role of Fluid properties conversion theory in the identification of sedimentary systems.