HR: 1340h
AN: S23B-0259    [Abstracts]
TI: Geophysical Constraints on the NY-AL Magnetic Lineament in the Eastern Tennessee Seismic Zone
AU: * Powell, C A
EM: capowell@memphis.edu
AF: Center for Earthquake Research and Information, University of Memphis 3876 Central Ave., Suite 1, Memphis, TN 38152-3050 United States
AU: Vlahovic, G
EM: gvlahovic@nccu.edu
AF: Department of Geography and Earth Sciences, North Carolina Central University, Durham, NC 27707 United States
AB: Isostatic gravity and total field magnetic data have been used in conjunction with a 3-D P-wave velocity model for the eastern Tennessee seismic zone (ETSZ) to model structural and lithologic variations along the prominent New York -Alabama (NY-AL) magnetic lineament. Potential field data along several cross sections were inverted to determine possible fault parameters, rock densities and susceptibilities, and plausible source rocks. Velocity cross sections were used only to specify the geometries of the prisms, not rock densities. The inversion resulted in models that reproduced the observed potential field anomalies with reasonable density and susceptibility values. Imaged velocity values and density values required by the potential field models follow a typical, density-velocity relationship and suggest the presence of rock types in the basement that are compatible with exposed Grenville rocks in Canada. The highly magnetic rocks producing the NY-AL lineament change dip from NW to SE along trend. This result cannot rule out a purely strike-slip origin for the lineament but suggests that other tectonic processes may have equal importance. The models suggest that the lineament may be a Grenville-age suture zone that juxtaposed crustal masses with different lithological properties. Most ETSZ earthquakes occur in basement rocks interpreted to be gneissic in composition and weaker than surrounding rock.
DE: 7205 Continental crust (1219)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7270 Tomography (6982, 8180)
DE: 7299 General or miscellaneous
DE: 8123 Dynamics: seismotectonics
SC: Seismology [S]
MN: Fall Meeting 2005