NEW INSIGHT INTO GLACIAL VARIABILITY BASED ON SEISMIC IMAGING OF SEDIMENTARY PACKAGES IN ICY BAY, ALASKA

Icy Bay, a glacially carved inlet on the southeastern coast of Alaska, has been progressively eroded through time by the combined advance and retreat of Tyndall, Yhatse, and Guyot glaciers. The marine sediment record of the bay records these system variations through time. Using this record, we have the ability to paint a very detailed picture of the history of Icy Bay which we can use to understand the current glacial system. We acquired new multi-channel seismic (MCS) and multibean bathymetry data sets from this region in August of 2016 to study the sediments in and around Icy Bay. We will utilize this integrated marine geophysical data-set to analyze the record of glacial sedimentation in the bay. This will allow us to improve our understanding of glacial retreat and variability between glacial systems during and spanning independent glacial cycles.

Preliminary observations in the MCS data reveal sediment structures through-out Icy Bay in a pattern corresponding to glacial advance and retreat. Variability in the geometry of terminal moraines and sediment accumulation document individual glacier fronts in time. This archive can be used to determine past system behavior. Once the data is fully processed and interpreted, we should be able to determine how the glaciers fluctuate during particular advance and retreat episodes. We should also be able to determine if these fluctuations are in sync, non-concurrent, or some combination of the two suggesting a linked, dependent system. This variability could then be expanded to provide insight into glacial activity from one advance-retreat cycle to the next.