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Experimental sequence stratigraphy of submarine fans on the basis of the theory of shoreline autoretreat

基于海岸线自动后退理论的海底扇层序地层学实验

基本信息

批准号：
12440139
负责人：
MURO Tetsuji
金额：
$ 5.38万
依托单位：
Nagasaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The present research was to investigate how the development of deep-water, coarse-grained clastic environments is related to shoreline autoretreat. This problem has been solved by means of flume experiments and theoretical examinations, summarized as below.Deepwater clastic depositional systems can respond sensitively with shoreline autoretreat River deltas cannot prograde over hundreds of kilometers across their shelves during the interval of highstand systems tract development. Even if unlimited time is available to delta growth, there is a clear limit in delta progradation owing to a mechanism ('autobreak') inbuilt in a delta evolving during relative sea-level rise. The termination of the progradation may be far landward of shelf edge. The main factors controlling the limit of delta progradation and the occurrence time of the autobreak event include shelf width, rate of sediment supply, rate of relative-sea level rise, and geometrical parameters of the delta and shelf. It is not abs … More olutely impossible for shelf-edge deltas to be built during slightly rising relative sea level. However, stillstand and falling relative sea level much favor the development of shelf-edge deltas and of sand supply to deep-marine areas, in terms of the delta's travel time to shelf edge. The present study therefore supports the maintenance of the conventional sequence stratigraphic interpretation that sand-rich deep-marine systems are most easily developed during falling and lowstand of relative sea level.A comprehensive understanding of the autogenic response of fluvial deltas to the steady forcing is provided from the theory of shoreline autoretreat. Besides, both autoincision and autobreak represent the moment at which the delta has to lose its original geometry. Any of autostepping and autogenic terrace formation comes out from the effect of the principle of shoreline autoretreat combined with its autocyclic behavior. Allocyclic changes of dynamic conditions only enhance or reduce the inbuilt process of delta systems. Less

本研究旨在探讨深水、粗粒碎屑环境的发育与海岸线自退的关系。通过水槽实验和理论验证，解决了这一问题。深水碎屑岩沉积体系响应灵敏，岸线自退，在高水位体系域发育期间，河流三角洲不能跨越陆架向前推进数百公里以上。即使三角洲的生长时间是无限的，三角洲的沉积也是有明显限制的，这是因为三角洲在相对海平面上升过程中演化的内在机制(“自动中断”)。陆架进积的终止可能在陆架边缘的远岸。控制三角洲进积极限和自破事件发生时间的主要因素有陆架宽度、沉积物供给速率、相对海平面上升速率以及三角洲和陆架的几何参数。这不是abs…更确切地说，在相对海平面略有上升的时候建造陆架边缘三角洲是不可能的。然而，就三角洲到陆架边缘的旅行时间而言，静止和相对海平面的下降更有利于陆架边缘三角洲的发育和向深海地区补砂。因此，本研究支持了传统的层序地层学解释，即相对海平面下降和下降时最容易发育富砂深海体系。从岸线自退理论出发，全面理解了河流三角洲对稳定强迫的自生响应。此外，自动切割和自动中断都代表三角洲必须失去其原始几何图形的时刻。任何一种自动台阶和自生阶地的形成都是岸线自退原理与其自旋回行为相结合的结果。动力条件的旋回变化只会增强或减弱三角洲体系的内生过程。较少