Paper No. 2
Presentation Time: 9:15 AM
IMAGING THE ANCIENT MARGIN: UPDATES FROM THE SOUTH EASTERN SUTURE OF THE APPALACHIAN MARGIN EXPERIMENT: SESAME
WAGNER, Lara S., Department of Geological Sciences, University of North Carolina - Chapel Hill, Chapel Hill, NC 27599, FISCHER, Karen M., Department of Geological Sciences, Brown University, Providence, RI 02912 and HAWMAN, Robert B., Department of Geology, University of Georgia, Athens, GA 30602, wagner@unc.edu
The east-west trending Brunswick magnetic anomaly is believed to delineate the southern suture zone between Gondwana and Laurentia during the Alleghanian orogeny. This suture is further defined by variations in the fossil record, rock compositions and ages, and seismic evidence from COCORP reflection profiles indicating southward-dipping reflectors in the crust that may indicate relict convergent margin structures. However, previous datasets have been unable to constrain mantle structures associated with this ancient tectonic boundary. The arrival of the Transportable Array to the East Coast promises to shed light on many broad scale mantle structures associated with the Appalachian Orogen. In Georgia, the Transportable Array stations will be complemented by the 85 broadband seismic stations of the South Eastern Suture of the Appalachian Margin Experiment (SESAME). These stations will be deployed in two north-south trending transects that retrace the COCORP lines across the Brunswick magnetic anomaly. A third transect will connect the northern edges of the two N-S transects along the NW-SE trending COCORP profile parallel to the Georgia-South Carolina border.
To date, over half of these SESAME broadband stations have been deployed, largely completing the western transect and much of the NW-SE transect. The remaining stations will be deployed in summer, 2012. Data from the SESAME deployment, together with Transportable Array stations, will help us image the mid- and lower-crust in addition to upper mantle structures. These images will help link observed crustal reflectors with mantle structures that in turn will help constrain vergence direction and the extent of Alleghanian shortening and volcanism in this area. The NW-SE trending transect will image the lower crustal and upper mantle structures beneath the Alleghanian thrust sheet which will help identify the locations of deep terrane boundaries along the eastern margin of Laurentia, and associate these with the shallow structures imaged by the reprocessed COCORP transect in the area.
