Stratigraphic and Tectonic Analysis of Neogene Coal-Bearing Basins Along the Alaska Range Suture Zone

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9725587 Ridgway This proposal seeks funding for a three-year investigation of Neogene sedimentary basins located along the north-central flank of the Alaska Range. These basins contain the record of basin development along an ancient suture zone, the uplift history of the highest mountain range in North America, extensive low-sulfur coal reserves, and potential petroleum reservoirs. The east-west trending basins were filled by fluvial and lacustrine deposits and consist of the Miocene Usibelli Group (~ 600 m thick) and the Pliocene Nenana Gravel (~ 1000 m thick). The general questions to be addressed include: (1) How do basins form within the interior of collisional/accretionary orogenic settings? Can a conceptual model be developed for basin formation along former suture zones? (2) What can the synorogenic deposits contained within these basins teach us about the Neogene uplift of the Alaska Range? Does the detrital record contain information on how deformation and uplift changed along strike and through time for this orogenic belt? What was the influence of paleoclimate on detrital composition during unroofing of the Alaska Range? (3) Coal from the Usibelli Group is becoming an increasingly important energy source for Alaska and for export to Pacific Rim countries. What were the depositional, tectonic, and climatic controls on coal deposition in these basins? A regionally integrated stratigraphic, paleogeographic and tectonic framework for all the Neogene basins will be needed to answer these questions. A database will be established by reconstructing the depositional systems for each basin; construction of a series of cross sections through the central Alaska Range; and compositional analysis of sandstone's and conglomerates. Major contributions of the proposed research include documentation of the long term evolution of sedimentary basins along a suture zone; delineation of along strike variations in the uplift history of the Alaska Range; and analysis of the distribution of potentially commercial coals for future exploration.