--> Using Outcrop, Subsurface and Modern Day Analogues to Predict Basin-Scale Alluvial Architecture for a Range of Tectonic and Climatic Settings

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Using Outcrop, Subsurface and Modern Day Analogues to Predict Basin-Scale Alluvial Architecture for a Range of Tectonic and Climatic Settings

Abstract

Models for alluvial architecture are important in predicting reservoir presence, distribution, quality and connectivity in continental basins. However coherent predictive models remain elusive except at a very broad scale as a clear relationship has yet to be established between accommodation space generation, depositional lithology (mudstone or sandstone) and alluvial architecture. In fact recent work has suggested that it is unlikely that any such relationship should exist. The realisation that distributive fluvial systems form an important component of modem and ancient continental basins has helped to increase the understanding of facies distributions at a basin-scale, however studies of distributive fluvial systems often lack temporal constraints. Here we use a combination of outcrop, subsurface and modern data together with a review of published data to develop a series of models for alluvial architecture in different tectonic, and climatic settings with variable subsidence rates and sediment supply. We include key architectural elements which include distributive fluvial systems, axial fluvial systems, valley development and a range of terminal facies such as wetlands, lake, play and aeolian. The data show that no clear relationship exists between subsidence rate and depositional lithology and subsidence rate and style of alluvial architecture when considered across all the studied basins. However when broken down by tectonic and climatic settings, clearer relationships can be established which can serve as predictive models for the subsurface. Models for rift and foreland basins will be discussed.