HR: 0800h
AN: T41A-0379    [Abstracts]
TI: Observations From Fieldwork and (U-Th)/He Thermochronologic Study of the Central Arabian Flank of the Red Sea Rift System
AU: * Szymanski, E
EM: eugene@ku.edu
AF: University of Kansas, Department of Geology, 1475 Jayhawk Blvd. 120 Lindley Hall, Lawrence, KS 66045-7613, United States
AU: Stockli, D F
EM: stockli@ku.edu
AF: University of Kansas, Department of Geology, 1475 Jayhawk Blvd. 120 Lindley Hall, Lawrence, KS 66045-7613, United States
AU: Johnson, P R
EM: Johnson.PR@sgs.org.sa
AF: Saudi Geological Survey, P.O. Box: 54141, Jeddah, 21514, Saudi Arabia
AU: Kattan, F H
EM: Kattan.FH@sgs.org.sa
AF: Saudi Geological Survey, P.O. Box: 54141, Jeddah, 21514, Saudi Arabia
AU: Al Shammari, A
EM: sha_sgs@yahoo.com
AF: Saudi Geological Survey, P.O. Box: 54141, Jeddah, 21514, Saudi Arabia
AB: Improvement in our modeling of continental lithosphere rupturing and rifting dynamics requires an absolute understanding of the temporal and spatial strain distribution throughout an entire rift system. This statement holds especially true for our understanding of Red Sea rift system dynamics. However, critical geologic data used to determine the tectonic evolution of the Red Sea rift system come mainly from the Gulf of Suez and the Egyptian and Yemeni margins of the Red Sea while the rift flanks in Sudan and Saudi Arabia have remained largely unstudied. This study aims to fill that information gap by focusing on the development of extensional structures and rift-related Tertiary basaltic volcanism along the central Saudi Arabian rift flank. Traditional structural analyses, coupled with thermochronometric techniques, are used to elucidate the temporal and spatial evolution of strain markers manifested by structurally-controlled extensional basins that parallel the trend of the main Red Sea rift. Constraints on the dynamics of rift flank deformation are achieved through the collection of long-baseline thermochronometric transects that traverse the entire Arabian shield and short-baseline transects that resolve the thermal evolution of individual normal faults that bound inland basins. The variation in sampling resolution is a comprehensive method that allows tectonic study at different scales; long-baseline transects aim to resolve the timing and kinematics of rift flank uplift and exhumation while short-baseline transects address issues well inboard from the modern rift margin such as structural control on pre- and syn-rift stratigraphy. Structural field analyses have shown that the NW-SE trend of inland basin-bounding faults is strongly coincident with the trend of pre-existing crustal fabrics produced by the Late Proterozoic Najd Fault System. Furthermore, the magnitude of normal fault activation along these heterogeneities controlled the geometry of inland basins. Preliminary (U- Th)/He apatite analysis of samples from both short- and long-baseline transects reveal a temporally dichotomous and spatially complex cooling history for the central rift flank that includes active footwall exhumation approximately 130 km inland from the rift margin during the Middle Miocene.
DE: 1140 Thermochronology
DE: 8109 Continental tectonics: extensional (0905)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting