Architecture characteristics of hyperpycnal deposits: Insights from numerical modeling with numerical simulation platform grade

Abstract

It is challenging to study hyperpycnal flow deposit characteristics, distribution, and internal architecture in detail using seismic or flume experiments. Therefore, a rule-based model Numerical Simulation Platform (NSP) Grade was developed to simulate various gravity-driven sediment transport processes and fan depositions in three dimensions. Five model scenarios are designed for processing and architecture studies of hyperpycnal flow deposits. Further, the impact of a single flow event’s duration and the flow occurrence was also discussed. The results show that in all scenarios, complex hyperpycnal flow strata stacked by channels, fans, and background shale according to specific rules were generated, and the progradation, retrogradation, and compensational stacking of hyperpycnal flow sediments were observed. Three facies can be identified in hyperpycnal flow depositions from proximal to the distal deposits, comprising channel complex, channel-fan transition deposits, and fan complex. Due to hyperpycnal deposit development, each event’s channel gradually becomes increasingly complex, and the channel extension distance decreases. The retrogradation characteristics of sedimentary bodies become more apparent. Shortening a flood event’s duration will lead to stronger deposition heterogeneity. Here multiple depositional centers will be formed. The distal center will form first, and sediments will gradually retrograde to form the next one. The reduced frequency of events results in less sediment supply, thinner thickness, and thicker mudstone barriers. NSP Grade revealed that numerical simulation could provide more realistic results than traditional interpretation models. Further studies on NSP Grade modeling will couple more processes and improve model accuracy to guide the understanding of hyperpycnal flow depositions.