异重流研究进展综述

基于国内外文献分析,从与经典浊流对比的角度,厘定了异重流的概念,探讨了异重流的形成机制、异重岩的结构特征以及异重流发育过程的模式。异重流是一种低密度准稳定的沉积物重力流。异重岩纵向剖面上通常由一个向上变粗和一个向上变细的沉积单元组成。异重流的形成与流体悬浮负载浓度密切相关,它的演化过程受气候条件、构造活动、沉积物供给以及相对海(湖)平面变化的控制,其中,气候条件最为重要。

Review of Hyperpycnal Flow

Based on reviewing the recent research progress, the nomenclature principle, the formation conditions, sedimentary characteristics and controlling factors of hyperpycnal flow are discussed, and some problems and corre-sponding countermeasures are proposed. Hyperpycnal flow can be described as low density, quasi-steady sedimenta-ry gravity flow, which is closely related to suspended particle concentration. The typical deposit or hyperpycnites se-quence is a compound of a basal coarsening-up unit (Ha) deposited during the waxing period of flood, and a top fining-up unit (Hb) deposited during the waning period of flood. The Ha-Hb transition corresponds to the maximum size and marks approximately the peak of the flood. The climate, tectonic activities, sediment supply and relative sea (lake) level change control the evolution of hyperpycnal flow. The climate is the most important factor that influ-ences the size of the rainfall and discharge, which controls the flood magnitude and frequency and directly decides the formation and evolution of hyperpycnal flow. In addition, more attention should be paid to ancient hyperpycnal flow deposits, facies models as well as modern observations and experimental simulation.