Collaborative Research: Late Pleistocene and Earliest Holocene Evolution of the Lower Mississippi Valley

Louisiana State University, Baton Rouge LA

Investigators

Abstract

0107028 Blum The Lower Mississippi Valley (LMV) has the potential of understanding the linkages of upstream climate/glacial vs. downstream sea level controls of a large stream system. In addition a stratigraphic and geochronologic framework for the alluvial landforms of the valley will aid in the study of tectonic activity within the New Madrid seismic zone, within the northern valley. This proposed research seeks to develop a chronologic and genetic model for evolution of the LMV during the Late Pleistocene full glacial (late Wisconsin stage) to the earliest Holocene, a period when rapid large-scale rearrangements of the North American hydrological system occurred. These rearrangements included changes in the Laurentide ice-sheet margin, drainage of pro-glacial lakes, and se level rise. This proposal focuses on a) the role of fluctuations in discharge and sediment load from the former ice margin, b) downstream effects of sea level discharge, and c) the impact of these forcing mechanisms on landscape evolution in the LMV. We hope to address the following questions: o How do landforms and deposits of the LMV correlate to ice margin changes, floods from pro-glacial lakes, and/or specific meltwater and sediment spikes identified in the Gulf of Mexico? o How do landforms and deposits of the LMV correlate to the landforms and deposits of the upper Mississippi valley where climate/glacail impacts were fundamental, but sea level played no role? o Does the LMV respond rapidly to high-frequency changes in discharge and sediment load during deglaciation, or are there lag times? Does the signal decay downstream or is it present to the Gulf of Mexico? o What is the influence of sea level and how far upstream does it extend?