Abstract
Autogenic processes are widely found in various sedimentary systems and they play an important role in the depositional evolution and corresponding sedimentary architecture. However, autogenic processes are often affected by changing allogenic factors and are difficult to be identified and analyzed from modern and ancient records. Through the flume tank experiment under constant boundary conditions, the depositional process, evolution principles, and the sedimentary architecture of a river-dominated delta was presented, and a corresponding sedimentary architecture model was constructed. The evolution of river-dominated delta controlled only by autogenic process is obviously periodic, and each autogenic cycle can be divided into an initial progradational stage, a middle retrogratational stage, and a late aggradational–progradational stage. In the initial progradational stage, one feeder channel incised into the delta plain, mouth bar(s) was formed in front of the channel mouth, and small-scale crevasse splays were formed on the delta plain. In the middle retrogradational stage, the feeder channel was blocked by the mouth bar(s) which grew out of water at the end of the initial stage, and a set of large-scale distributary splay complexes were formed on the delta plain. These distributary splay complexes were retrogradationally overlapped due to the continuous migration of the bifurcation point of the feeder channel. In the late aggradational–progradational stage, the feeder channel branched into several radial distributary channels, overlapped distributary channels were formed on the delta plain, and terminal lobe complexes were formed at the end of distributary channels. The three sedimentary layers formed in the three stages constituted an autogenic succession. The experimental delta consisted of six autogenic depositional successions. Dynamic allocation of accommodation space and the following adaptive sediments filling were the two main driving factors of the autogenic evolution of deltas.
Highlights
There are a number of controlling factors that govern the depositional processes and the internal architecture of a sedimentary system including water and sediment supply, climatic changes, base-level variation, tectonic activities, and so on (Gong et al 2016; Jia et al 2018; Jia et al 2016; Ventra et al 2018; Zhao et al 2018a; Zhao et al 2018b)
To understand the evolution of the depositional process and the resulting sedimentary architecture of the experimental delta, we developed a program with MATLAB for the analysis of the digital elevation models (DEMs)
The feeder channel incised into the delta plain and was unfilled during the initial stage (Fig. 10)
Summary
There are a number of controlling factors that govern the depositional processes and the internal architecture of a sedimentary system including water and sediment supply, climatic changes, base-level variation, tectonic activities, and so on (Gong et al 2016; Jia et al 2018; Jia et al 2016; Ventra et al 2018; Zhao et al 2018a; Zhao et al 2018b). Flume experiments were used for investigating the autogenic process of fan delta (Van Dijk et al 2009), fluvial delta (Foreman and Straub 2017; Carlson et al 2018) using non-cohesive sediment and constant sea level (not constant relative base level). These types of sedimentary systems usually developed in arid and semiarid climate. The experimental studies on autogenic process-controlled river-dominated deltas using cohesive sediment and constant relative base level are very limited (Straub et al 2015). Based on the analysis of the autogenic process and the internal architecture of the experimental delta, six autogenic cycles have been identified
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