晚第四纪下切河谷体系研究综述  

Review of Late Quaternary incised valley system

作　　者：林春明[1] 张霞[1] 黄舒雅 LIN Chunming;ZHANG Xia;HUANG Shuya(State Key Lab for Mineral Deposits Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing,210023)

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室,南京大学地球科学与工程学院,南京210023

出　　处：《地质论评》2022年第2期627-647,共21页Geological Review

基　　金：国家自然科学基金资助项目(编号:42172107,41772097,42172105)的成果。

摘　　要：下切河谷的研究不仅可以正确划分地层、确立年代地层格架、判定沉积环境演变、探讨海平面变化规律,对碳氢化合物勘探开发、地质工程等重大国民经济建设也有重要意义。本文介绍了下切河谷体系概念、特征、划分类型、研究历程和科学意义,着重论述了晚第四纪下切河谷的形成演化、层序地层格架和控制因素。晚第四纪下切河谷体系主要是海平面下降、河流向盆地扩展并侵蚀下伏地层的下切河流体系,在海平面上升时期被充填的长条状负向地形,以区域性的地层不整合面为底界。浪控型与潮控型下切河谷体系模式有许多不同之处:①前者存在河口砂坝、中央盆地、湾顶三角洲,后者则没有这些沉积单元;②前者浅海沉积较薄,后者较厚;③前者代表了贫砂的小河河口湾,由于泥砂量少,河口湾在最大海侵线附近,后者河流作用较强,泥砂量相对大,现代河口湾不断向海扩展,较下切河谷范围要大的多;④前者涉及溯源堆积在下切河谷充填中的作用,但对其强度估计不足。下切河谷体系的形成演化的影响因素众多,海平面变化、沉积物供应、沉积过程、下切河谷形态和气候变化等是主要控制因素。The study of incised valleys not only can classify stratigraphy,establish the chronostratigraphic framework,determine the evolution of sedimentary environment,and explore the pattern of sea-level change but also has important significance to the exploration and development of hydrocarbons,and other national economic construction.This paper introduces the concept,characteristics,types,research history and scientific significance of the late Quaternary incised valley system,with the emphasis on the formation,filling evolution of incised valley,sequence stratigraphic framework,the difference between tide and wave-dominated incised valley systems,and the controlling factors and comparison of deposition patterns of incised valleys.The late Quaternary incised valley systems are fluvially eroded,elongate palaeotopographic lows developed during episodes of relative sea-level fall,and subsequently infilled and reworked by fluvial,coastal and marine processes during sea-level rise,with the regional stratigraphic unconformability as the bottom boundary.There are many differences between wave and tide-dominated incised valley systems:①the former commonly develop rivermouth bars,central basin and bayhead delta,and the sediments typically exhibit a coarse—fine—coarse grain-size distribution while the latter systems do not develop these sedimentary units,and the sediments present a coarse—fine—coarse—fine grain-size distribution;②the shallow-marine sediments are thin in the wave-dominated incised valley systems but the relatively thick shallow-marine sediments were deposited in the latter systems;③the former systems represent sand-poor small river estuaries,which are near the line of maximum transgression due to low mud and sand volume;the latter have stronger fluvial action and relatively high mud and sand volume,thus modern estuaries are constantly expanding seaward,with a much larger extent than incised valleys;④the former involve the role of retrogressive accumulation in the filling of incised valleys,but

关 键 词：下切河谷 形成与演化 层序地层格架 潮控型下切河谷体系 晚第四纪 

分 类 号：P534.63[天文地球—第四纪地质学]