A comparative analysis of the tetonic response of warm and cool water carbonate platforms in contrasting retroarc foreland basins

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The position of sea level in a sedimentary basin reflects a balance among three factors: global changes in climate; environmentally intrinsic factors that influence sediment accumulation; and tectonic controls linked directly and indirectly to plate-boundary dynamics. The subordinant role of tectonism is well known for carbonate platforms along trailing or passive margins, but the potential spectrum of tectonic influences on platform stratigraphy within foreland basins along convergent plate boundaries is less well defined. The proposed research, to include both outcrop, core, and laboratory analyses, will examine the geological record of tectonic influence and the resulting patterns of carbonate accumulation within two contrasting foreland-basin successions. First, the the Ottawa Embayment (eastern Ontario), within which a Middle to Upper Ordovician (460-450 million years) interior portion of a tropical carbonate platform lay in a foreland basin that defines a history of subsidence behind an ancient (Taconic) volcanic arc. Second, the Austral Basin (Patagonia), within which thin accumulations of cool-water carbonates of late Paleogene-early Neogene (26-15 million years) age occur within a siliciclastic foreland basin that defines mostly uplift behind an Andean arc. The first basin also overlies an ancient continental rift system, and several intrabasinal projects will examine to what extent the mechanically weakened underlying crust may have additionally influenced the younger basin's response to distal plate-boundary convergence. A detailed sequence stratigraphic framework for each foreland platform succession will be compared with contemporary basins that lay beyond the zone of convergence. This approach will allow an improved understanding of the scales and paleogeographic breadth of tectonics that can influence sedimentation patterns in foreland basins hosting cool- and warm-water carbonate systems.