HR: 09:20h
AN: U51B-05    [Abstracts]
TI: GPS Constraints on Continental Deformation in the Africa-Arabia-Eurasia Continental Collision Zone and Implications for the Dynamics of Plate Interactions
AU: * Reilinger, R
EM: reilinge@erl.mit.edu
AF: Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, MA 02142 United States
AU: McClusky, S
EM: simon@mit.edu
AF: Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, MA 02142 United States
AU: Vernant, P
EM: vernant@mit.edu
AF: Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, MA 02142 United States
AB: We present a GPS-derived velocity field (1988-2005) for the zone of interaction of the Arabian, African (Nubian and Somalian), and Eurasian plates. The velocity field indicates counterclockwise rotation of a broad area of the Earth's surface that includes the Arabian plate, adjacent parts of the Zagros and central Iran, Turkey, and the Aegean/Peloponnesus (>7 x 10⁶ km² 5% of the Earth's total surface area) at rates in the range of 20 to 30 mm/yr. This relatively rapid motion occurs within the framework of the slow-moving (<5 mm/yr relative motions) Eurasian, Nubian, and Somalian plates. The circulatory pattern of motion increases in rate towards the Hellenic trench system, suggesting to us that subduction in the eastern Mediterranean is the dominant process responsible for regional deformation. Using seismic and other geophysical and geological information, we develop an elastic block model and use the GPS velocity field to estimate relative block motions. We constrain present-day motions of the Nubian, Somalian, Arabian, and Eurasian plates (relative Euler vectors), regional deformation within the inter-plate zone, and slip rates for major faults. With some important exceptions, geodetic slip rates for major block-bounding structures are comparable to geologic rates estimated for the most recent geological period (3-5 Ma). We find that the convergence of Arabia with Eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the Caucasus and Zagros mountain belts around the periphery of the collision zone, with little fault-normal convergence within eastern Turkey and the Lesser Caucasus. In addition, we find that the principal boundary between the westerly moving Anatolian plate and Arabia (East Anatolian fault) is presently characterized by pure left-lateral strike slip with no fault-normal convergence and possibly small extension, implying that "extrusion", in the sense of pushing along the plate interface, is not inducing westward motion of Anatolia. Based on the broad spatial scale of the observed deformation, the increasing rate of motion towards the Hellenic-Cyprus trench system, and the approximate balance between surface area consumed at trenches and created at ridges, we hypothesize that deformation in the Africa-Arabia-Eurasia collision zone is driven in large part, if not entirely, by rollback of the subducting African lithosphere beneath the Hellenic and Cyprus trenches aided by slab pull on the northeastern side of the subducting Arabian plate along the Makran subduction zone. We further suggest that rifting in the Red Sea and Gulf of Aden is a response to plate motions induced by active subduction.
DE: 1209 Tectonic deformation (6924)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 8107 Continental neotectonics (8002)
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8158 Plate motions: present and recent (3040)
SC: Union [U]
MN: Fall Meeting 2005