Intra-continental Deformation, Susitna River Basin Margins, Alaska
Julie B. Willis
University of Utah, Department of Geology and Geophysics
Salt Lake City, UT
Fault-cored, anticlinal ridges adjacent to the Susitna River basin, south-central Alaska appear to actively propagate into the basin under thick glacial fill. Anomalies in planform channel geometries and longitudinal profiles of rivers that cut the basin correspond with subjacent anticlines. To quantify rates and timing of uplift and to further test whether the anticlines are actively propagating, apatite fission track and low temperature U/Th-He dating are underway on eighteen previously collected granitic samples. Funding from AAPG is helping to pay for the laboratory costs associated with the dating. Apatite grains from all samples are separated, and the apatite for fission track dating are irradiated and currently cooling. Apatite grains for low temperature thermochronology are prepared and are at the low-temperature thermochronology lab at CalTech awaiting final processing. A few additional samples were collected early this summer and dating is also underway on them. Other aspects of the research are also progressing. Numerical models that compare stress transfer from subduction thrust earthquakes into the continental interior are designed and the results, which will be presented at a professional meeting in December, currently are being evaluated and compared with tectonic features. A true three-dimensional, interactive, and geographically-referenced map of surface mapping, topography, stream analyses, thermochronology models, and numerical models is under construction using GEON IDV (Integrated Data Viewer). The map will be used to uncover relationships between modeled, field, and seismic data that otherwise may be unnoticed.
AAPG Search and Discovery Article #90060©2006 AAPG Foundation Grants-in-Aid