ABSTRACT: A model, based upon pre-existing formulations, is presented here for alluvial sequence stratigraphy and applied to the non-marine, Paleoproterozoic Baker Lake Basin. Discharge and sediment supply are considered boundary conditions, subject to feedback effects. Primary control on alluvial facies changes is attributed to the gradient of the alluvial plain. This gradient is determined by the “graded profileâ€, a topographic profile defined by a graded stream linking a sediment source region to a subaqueous basin. It is argued that coupled source uplift and basin subsidence provide feedback on sediment supply, grade, and flux that reinforce expected facies changes, in part providing justification of initial assumptions. The model provides a rationale for a generally upward-fining alluvial sequence that is coeval with a general upward-fining to –coarsening nearshore sequence, bridging the theoretical gap between subaerial and subaqueous sequences. It also provides an interpretation of basin-scale stratigraphy based on the tectonic evolution of sedimentary basins, in keeping with the models for how they form. Third-order depositional sequences of tectonic origin from the Baker Lake Basin are subdivided into high accommodation alluvial, low accommodation alluvial, and mixed fluvial-shallow-lacustrine sequences. The succession of 3rd order sequences illustrates basin evolution from rift initiation, rift climax accompanied by widespread volcanism, to immediate post-rift that comprises the 2nd order Baker Sequence, representing a stage of intracontinental rifting from ca. 1.84-1.79 Ga.
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