HR: 09:15h
AN: T41E-06    [Abstracts]
TI: Quaternary Transform Kinematics Constrained by Sequence Stratigraphy and Submerged Coastline Features: The Gulf of Aqaba
AU: * Makovsky, Y
EM: yizhaq@bezeqint.net
AF: Recanati Institute for Marine Studies, University of Haifa, Mt. Carmel, Haifa, 31905, Israel
AU: Wunch, A
EM: assafwunsch@yahoo.com
AF: Institute of Earth Sciences, Hebrew University, Givat Ram, Jerusalem, 91904, Israel
AU: Ariely, R
EM: ronenari@gii.co.il
AF: Geophysical Institute of Israel, P.O.B 182, Lod, 71100, Israel
AU: Shaked, Y
EM: shakedyo@cc.huji.ac.il
AF: The Interuniversity Institute for Marine Sciences at Elat, P.O.B 469, Elat, 88103, Israel
AU: Rivlin, A
EM: asaphr@vms.huji.ac.il
AF: The Interuniversity Institute for Marine Sciences at Elat, P.O.B 469, Elat, 88103, Israel
AU: Shemesh, A
EM: aldo.shemesh@gmail.com
AF: Department of Environmental Sciences & Energy Research, Weizmann Institute of Science, P.O.B, Rehovot, 76100, Israel
AU: Ben Avraham, Z
EM: zviba@post.tau.ac.il
AF: Department of Geophysics & Planetary Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv, 69978, Israel
AU: Agnon, A
EM: amotz@cc.huji.ac.il
AF: Institute of Earth Sciences, Hebrew University, Givat Ram, Jerusalem, 91904, Israel
AB: The northern head of the Gulf of Aqaba is a zone of transition between major segments of the Dead Sea Fault System (DSFS), and where this fault system crosses the evolving continental shelf. This paper is based mainly on detailed processing and interpretation of a grid of high resolution Chirp sub-bottom profiles we acquired in 2002 along the western side of this shelf down to a depth of about 120m. Our data reveal stepping seafloor morphology comprising a series of relict coastline features, primarily fossil reefs, that reached their current depth as a combined result of eustatic sea level rise and tectonic displacements. On the north slope the fossil reefs are embedded in up to about 30 m thick, predominantly single phase, retrograde sedimentary stack that evolved presumably during the most recent phase of sea level rise since the last glacial maximum, about 20 Ka ago. Large variations in the sedimentary character within this sedimentary stack bear evidence for large episodic changes in the rates of sea level rise and the ensuing environmental conditions during the Holocene. A prominent terrace-face complex, a relict coastline feature, sub-parallels the shoreline outlining at a depth of about 100 m an internal basin. This face-terrace complex accommodated on the order of 10 m down to the east vertical offsets across the surveyed area since its creation, presumably late Pleistocene to early Holocene. The trace of an active strike slip fault crossing the north slope is defined by: a. NE striking bathymetric features; b. discontinuities offsetting the sedimentary layering from just below the sea floor to the deepest layers imaged; c. a 30±10 m sinistral and 10±1 m down to the east offset of a fossil reef at a depth of about 65 m. Global sea level curves constrain the age of the 65-m reef to 11±2 Ka yielding an estimated average Holocene sinistral slip rate of 2.7±1.5 mm/yr, in the order of half the regional slip of the DSFS. We conclude that the revealed fault is a principal strand of the DSFS continuing to the south the Avrona fault in a left stepping manner. Segmentation to echelon segments, as inferred here for the Avrona fault, may be a typical pattern for the accommodation of strike slip at tips of transform basins.
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 7221 Paleoseismology (8036)
DE: 7250 Transform faults
SC: Tectonophysics [T]
MN: 2007 Fall Meeting