HR: 1340h
AN: T43A-1087    [Abstracts]
TI: Tectonic Activity and Processes Preceding the Formation of the Dead Sea Fault Zone
AU: * Eppelbaum, L V
EM: levap@post.tau.ac.il
AF: Dept. of Geophysics, Tel Aviv University, Ramat Aviv, Tel Aviv, 69978, Israel
AU: Pilchin, A N
EM: apilchin1521@rogers.com
AF: Univ. Geosci. and Environ. Consult. Comp., 205 Hilda Ave., Willowdale, Ontario, M2M 4B1, Canada
AB: Analysis of geological-geophysical data indicates that at the end of the Proterozoic, blocks of the Arabian Shield (AS) were thrust to the north-west onto the crust of the proto-Mediterranean (PM). This was caused by the pushing of oceanic crust from the south-east forming the Najd faults system (NF). This thrusting took place between 630 and 590 Ma, and is confirmed by the offsets between the Yanbu suture of the AS and Allaqi-Sol Hamid suture of the Nubian Shield (NS), the Bi'r Umq suture of AS and Nakasib suture of NS, and parts of the Yanbu and Nabitah sutures of AS. This caused the separation of AS from NS, and AS from the continental crust to north-east of it with its north-western displacement, resulting in opening of the Persian Gulf. This caused the start of deposition of huge amounts of Vendian-Cambrian evaporites in Saudi Arabia, Oman, Persian Gulf, Zagros, central Iran and other regions. The fact of the formation and preservation of the evaporites, and the common similarities in Vendian-Triassic sedimentary cover of Central Iran, Zagros, Taurus, and Arabian Plate (AP) and common Late Proterozoic–Early Paleozioc magmatic activity, show that these regions did not change their position significantly since then. Results of the DESERT project show that the lowermost part of the crust is present east of the Dead Sea Fault Zone (DSFZ), but it is absent west of it. This could be explained by detachment of the bottom part of the crust west of DSFZ during AP thrusting onto the crust of PM. The lithospheric slice discovered by seismic data between Moho and depth of about 55 km in S. Israel could be a remnant of that crust. During the thrusting, the AP overrode the detached slice. The slice was later remelted during formation of the postorogenic magmatic rocks of 590-530 Ma widespread in Jordan. The formation of three dyke swarms in S. Israel (600-540 Ma), widespread dykes in Sinai (590-530 Ma) and AP (590-530 Ma), as well as high-T-low-P metamorphism between 600 and 530 Ma, point to a huge release of heat likely caused by friction during the thrusting. Presence of giant quantities of K-rich granites also points to reworking of continental crust in the region. Small amount of magmatic formations younger than Cambrian age west of DSFZ and significant amount of magmatic formations of this period east of DSFZ also indicate to presence of the plate beneath Israel. Offset of suture zones within AS shows that displacement was maximal for the northern blocks of AS. This is in agreement with known separation of Israel's crust into three blocks: Negev, Judea-Samaria and Galilee- Lebanon. Numerous markers of high to ultra-high pressure conditions signify to collision between the AP and the PM. These markers are: iron rich aegerine-augite and olivine-rich phenocrysts in S. Israel; peridotite xenoliths in S. Israel equilibrated at depth ~33-34 km; discovery of diamonds, micro-diamonds and indicator minerals (Cr- diopside, orange garnet, pyrope, coesite, picroilmenite, moissanite, carbonado, corundum, olivine, perovskite, aegerine, Ti-augite) in S. Israel; garnet clinopyroxenites, garnet granulites, indicator minerals, and eclogite-like rocks in Mt. Carmel area of N. Israel; iron-rich garnets in Sinai; eclogites, diamonds and indicator minerals in non-kimberlite environments in Syria; ophiolites exposed in Syria at northern extension of the DSFZ; ophiolite-like rocks in Sinai. These markers are located along or in close proximity to the DSFZ. Different isostatic conditions east of the edge of- and above- the underlying plate, along with the eventual activation of the plate caused the later formation of the DSFZ.
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8002 Continental neotectonics (8107)
DE: 8036 Paleoseismology (7221)
DE: 8106 Continental margins: transform
SC: Tectonophysics [T]
MN: 2007 Fall Meeting