HR: 0800h
AN: G21B-1267    [Abstracts]
TI: Assessing the Rigidity of the Puerto Rico-Virgin Islands Microplate: Results from GPS Geodesy in the British Virgin Islands
AU: * Stamps, D S
EM: dsstamps@memphis.edu
AF: University of Memphis, Department of Earth Sciences 001 Johnson Hall, Memphis, TN 38152 United States
AU: Baldwin, A
EM: yohomeboyab@yahoo.com
AF: University of Arkansas, Department of Geosciences 113 Ozark Hall, Fayetteville, AR 72702 United States
AU: Turner, H
EM: hturner@uark.edu
AF: University of Arkansas, Department of Geosciences 113 Ozark Hall, Fayetteville, AR 72702 United States
AU: Mattioli, G
EM: mattioli@uark.edu
AF: University of Arkansas, Department of Geosciences 113 Ozark Hall, Fayetteville, AR 72702 United States
AU: Jansma, P
EM: pjansma@uark.edu
AF: University of Arkansas, Department of Geosciences 113 Ozark Hall, Fayetteville, AR 72702 United States
AB: Recent studies provide evidence of three microplates defined by the Puerto Rico trench to the north and the Muertos trough to the south in the boundary zone between the North America and Caribbean plates in the northeastern Caribbean. From west to east, these are the Gonave, Hispaniola, and Puerto Rico-northern Virgin Islands (PRVI) microplates. The eastern and western boundaries of the Gonave and Hispaniola microplates and the western boundary of the PRVI microplate have been defined in previous studies. However, the easternmost terminus of PRVI is undetermined, but suspected to lie either within or at the eastern terminus of the British Virgin Islands (BVI). Previously reported geodetic data indicates east-west extension across Puerto Rico and between eastern Puerto Rico and Virgin Gorda in the BVI. Our 2005 campaign focused on defining the easternmost terminus of PRVI and testing the extensional hypothesis by collecting surface motion data using Global Positioning System (GPS) geodesy. We collected data at sites on Tortola and Anegada in the BVI and concluded that the GPS-derived velocities of Tortola and Anegada with respect to the Caribbean are 5.71 + 5.5 mm/yr to the NNW (one sigma) and 3.12 + 2.7 mm/yr to the WNW (one sigma), respectively. These velocities are similar to those of eastern Puerto Rico. No motion relative to the Caribbean for Tortola and Anegada also is a possibility within error. If the GPS-derived velocities of Tortola and Anegada are 3-5 mm/yr, little to no east-west extension occurs between the BVI and eastern Puerto Rico, implying that PRVI is rigid at the mm/yr level and that the eastern terminus of PRVI coincides with the eastern end of the BVI near Virgin Gorda.
DE: 1299 General or miscellaneous (1709)
SC: Geodesy [G]
MN: Fall Meeting 2005