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Uplift and denudation history of the eastern Dead Sea rift flank, SW Jordan: Evidence from apatite fission track thermochronometry S. Feinstein, 1 M. Eyal, 1 B. P. Kohn, 2 M. S. Steckler, 3 K. M. Ibrahim, 4 B. K. Moh’d, 5 and Y. Tian 2 Received 13 March 2013; revised 29 August 2013; accepted 12 September 2013. [1] The Dead Sea rift (DSR), developed along the Dead Sea transform plate boundary, is characterized by salient flanks and morphotectonic asymmetry. Apatite fission track thermochronology (AFT) along ~1200 m high vertical profiles in Neoproterozoic basement and overlying Cambrian sandstone in southwestern Jordan is used to reconstruct timing, magnitude, and rate of uplift and denudation of the eastern DSR flank and examine its relationship to rift development and its flank landscape. Time-temperature models based on AFT data suggest three major Phanerozoic heating and cooling episodes, Late Paleozoic, Early Cretaceous, and Oligocene. The latest episode, on which this study focuses, indicates uplift of ~3.8±0.3 km under a moderate paleogeothermal gradient. About 40% of the uplift was tectonically driven with the remainder attributed to isostatic rebound in response to denudation and erosion. Models suggest that uplift commenced in the Oligocene with a considerable part occurring prior to development of the DSR, despite being ~200 km from the Red Sea-Gulf of Suez rift margin. Uplift is probably part of a regional rearrangement along the western Arabian platform margin occurring at the time of Red Sea rift initiation. Transition from primarily sedimentary layer stripping, most likely by scarp retreat, to one of dominantly incision of the underlying crystalline basement occurred in Late Miocene-Pliocene time following enhanced subsidence and development of a low base level in the DSR. Consequently, the magnitude of uplift by isostatic rebound due to incision exceeded lowering by surface truncation and increased summit elevation and riftward flexing of the flank. Citation: Feinstein, S., M. Eyal, B. P. Kohn, M. S. Steckler, K. M. Ibrahim, B. K. Moh’d, and Y. Tian (2013), Uplift and denudation history of the eastern Dead Sea rift flank, SW Jordan: Evidence from apatite fission track thermochronometry, Tectonics, 32, doi:10.1002/tect.20082. 1. Introduction [2] The Dead Sea transform (DST) is an en echelon fault system extending from the northern edge of the Red Sea in the south to the Taurus Mountains of the Alpine Orogenic Belt in Turkey in the north (Figure 1a). The DST divides the northern margin of the Arabo-Nubian shield into the Arabian plate and Sinai subplate, which have been displaced left later- ally along its trace by up to ~105 km since middle Miocene time [Quennell, 1959a, 1959b; Freund et al., 1970; Eyal et al., 1981; Garfunkel, 1981, 2001; Bosworth et al., 2005]. [3] The Dead Sea rift (DSR) is a relatively narrow Neogene structure formed along the central part of the DST (Figure 1a). It contains the world’s deepest continental depression and is characterized by conspicuously high-standing flanks with prominent structural and morphological asymmetries [Ben- Avraham and Zobak, 1992; Wdowinsky and Zilberman, 1997]. The western flank of the DSR is characterized by an upwarped arch, which dips moderately toward the rift whereas, elevations on the eastern flank uplift increase west- ward forming a prominent rift-facing escarpment with strata dipping moderately eastward, away from the rift. Uplift of the eastern flank is considerably greater than that on the west- ern side and its current elevation is considerably higher. [4] Flank uplifts and their structural and morphological asymmetry are common characteristics of intercontinental rift basins and rifted continental margins (e.g., southern Red Sea, Gulf of Suez, southwest Africa, eastern Brazil). The timing, 1 Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel. 2 School of Earth Sciences, University of Melbourne, Melbourne, Victoria, Australia. 3 Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA. 4 Department of Earth and Environmental Sciences, Faculty of Natural Resources and Environment, Hashemite University, Zarqa, Jordan. 5 Department of Civil Engineering, College of Engineering, Tafila Technical University, Tafila, Jordan. Corresponding author: S. Feinstein, Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel. ([email protected]) ©2013. American Geophysical Union. All Rights Reserved. 0278-7407/13/10.1002/tect.20082 1 TECTONICS, VOL. 32, 1–16, doi:10.1002/tect.20082, 2013
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Figure 14. Electro-optic modulator retardation for oblique rays
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