深水重力流沉积研究进展

A Review of Deep-Water Gravity-Flow Deposition Research

深水重力流沉积研究经历了半个多世纪发展,从浊流及鲍马序列开始,到把深水砂岩普遍解释为浊流成因以及海底扇模式的建立,再到今天学者们对鲍马序列的质疑,深水重力流沉积的研究经历了认识上的螺旋式上升旋回。目前关于深水重力流沉积争议的焦点在于高密度浊流是否属于浊流的范畴,深水砂岩是否都是浊流成因。以Shanmugam为代表的学者认为,绝大多数的深水砂岩都是碎屑流成因而非浊流成因,并且提出了重力流分类新方案,同时建立了与其匹配的深水斜坡沉积模式。通过对前人成果的广泛调研,经过对比总结,认为:1根据流变学和沉积物搬运机制,重力流分为碎屑流(砂质碎屑流和泥质碎屑流)、颗粒流、浊流;2浊流的韵律结构特征为明显的正粒序且没有漂浮的碎屑颗粒,碎屑流自下而上呈逆-正粒序的两套韵律变化且发育有漂浮的碎屑颗粒;3Walker的综合扇模式与Shanmugam的斜坡沉积模式,二者是可以共存的,只是在某一地区适用性不同而已。

The study of deep-water deposition has been ongoing through half a century. From the theory of turbidity currents and Bouma sequence, to the understanding of deep-water sandstone as the turbidity cur- rents and the foundation of seabed fan depositional mode, and then to the chanllenge and doubt to the theo- ry of Bouma sequence, the study on deep water deposition has undergone spiral circle on cognition ap- proach. Today, the main controversy focuses on whether the turbidity is categorized into high or low den- sity turbidity currents and whether all deep water sandstones are induced by the turbidity current. Taking Shanmugam as the representative, group of scholars believe that the vast majority of deep-water sand- stones are caused by sandy debris but not by turbidity currents, and they also propose a new classification scheme of sediment gravity flow and establish the matching depositiona[ model of deep water slope. Based on the contrasting and summarizing results from previous researches, this paper concludes that： （1） Sedi- ments gravity flow can be divided into turbidity current, grain flow, sandy debris flow and muddy debris flow according to the gravity flow classification method of rheology and the mechanism of sediment trans- port; （2） Turbidity currents have normal grading without floating clastic particles and debris flows have inverse to normal grading with floating clastic particles; （3） Generalized deposition model of Walker and Slop deposition model of Shanmugam can coexist but the applicability of them are various in certain area.