Tectonic evolution of the Qumran Basin from high-resolution 3.5kHz seismic profiles and its implication for the evolution of the northern Dead Sea Basin (original) (raw)
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The Northern end of the Dead Sea Basin: Geometry from reflection seismic evidence
Tectonophysics, 2007
Recently released reflection seismic lines from the Eastern side of the Jordan River north of the Dead Sea were interpreted by using borehole data and incorporated with the previously published seismic lines of the eastern side of the Jordan River. For the first time, the lines from the eastern side of the Jordan River were combined with the published reflection seismic lines from the western side of the Jordan River. In the complete cross sections, the inner deep basin is strongly asymmetric toward the Jericho Fault supporting the interpretation of this segment of the fault as the long-lived and presently active part of the Dead Sea Transform. There is no indication for a shift of the depocenter toward a hypothetical eastern major fault with time, as recently suggested. Rather, the north-eastern margin of the deep basin takes the form of a large flexure, modestly faulted. In the N-S-section along its depocenter, the floor of the basin at its northern end appears to deepen continuously by roughly 0.5 km over 10 km distance, without evidence of a transverse fault. The asymmetric and gently-dipping shape of the basin can be explained by models in which the basin is located outside the area of overlap between en-echelon strike-slip faults.
Holocene tectonic deformation along the western margins of the Dead Sea
Tectonophysics, 1990
To assess the young tectonic activity along the western margins of the Dead Sea and north of the lake, faults were studied within sediments which are up to 60,000 years old. The western margins of the Dead Sea are dominated by normal, step faults which are exposed up to 2 km east of the morphological escarpment of the basin. The rate of subsidence accommodated by these normal faults is estimated to be about 0.85 mm/y. The distribution of the faults suggests that Holocene fault activity was most intense in the northwestern comer of the Dead Sea. North of the lake, left-lateral slip along the Jordan fault produced both local compression and extension. Small reverse faults and folds exposed along this fault indicate a minimum left-lateral slip rate of 0.7 mm/y.
Anatomy of the Dead Sea transform: Does it reflect continuous changes in plate motion?
Geology, 1999
A new gravity map of the southern half of the Dead Sea transform offers the first regional view of the anatomy of this plate boundary. Interpreted together with auxiliary seismic and well data, the map reveals a string of subsurface basins of widely varying size, shape, and depth along the plate boundary and relatively short (25-55 km) and discontinuous fault segments. We argue that this structure is a result of continuous small changes in relative plate motion. However, several segments must have ruptured simultaneously to produce the inferred maximum magnitude of historical earthquakes.
The crustal structure of the Dead Sea Transform
2004
To address one of the central questions of plate tectonics – How do large transform systems work and what are their typical features? – seismic investigations across the Dead Sea Transform (DST), the boundary between the African and Arabian plates in the Middle East, were conducted for the first time. A major component of these investigations was a combined reflection/refraction survey across the territories of Palestine, Israel and Jordan. The main results of this study are: (1) The seismic basement is offset by 3-5 km under the DST, (2) The DST cuts through the entire crust, broadening in the lower crust, (3) Strong lower crustal reflectors are imaged only on one side of the DST, (4) The seismic velocity sections show a steady increase in the depth of the crust-mantle transition (Moho) from ~26 km at the Mediterranean to ~39 km under the Jordan highlands, with only a small but visible, asymmetric topography of the Moho under the DST. These observations can be linked to the left-lateral movement of 105 km of the two plates in the last 17 Myr, accompanied by strong deformation within a narrow zone cutting through the entire crust. Comparing the DST and the San Andreas Fault (SAF) system, a strong asymmetry in subhorizontal lower crustal reflectors and a deep reaching deformation zone both occur around the DST and the SAF. The fact that such lower crustal reflectors and deep deformation zones are observed in such different transform systems suggests that these structures are possibly fundamental features of large transform plate boundaries.
Marine and Petroleum Geology, 2006
Interpretation of recently released seismic reflection lines from the Shuna (Eastern Jericho) Basin combined with re-analysis of the lithologic logs of the deep JV-1 and JV-2 boreholes provide new insights into the structure of the sedimentary basin that formed along the Dead Sea Transform fault north of the Dead Sea in Jordan. We identified four major seismic boundaries in the reflection profiles. The upper two were correlated with borehole stratigraphy. These reflection boundaries include the top of the pan-African basement (R4), the base of the Mesozoic (R3), the base of the Cretaceous (R2), and the base of the post-Eocene section (R1). The latter records sedimentation during the Dead Sea Transform tectonic regime. The total thickness attained by the older sedimentary units (Late Cretaceous through Cambrian) is apparently less than 2 km. We identified a subsurface structure, a faulted monocline, with a N-S trend, sub-parallel to the strike of the Dead Sea Transform, that is named here Al Kharrar monocline. The Al Kharrar structural ensemble is buried by syntectonic lacustrine and fluviatile sediments of the Jordan Valley Group. The structure formed as part of the Dead Sea Transform deformation overprinting the Late Cretaceous Syrian arc folds. Continued tectonic deformation is evident from the prominent unconformity at the base of post-Eocene syntectonic deposits that dip NW, W and S away from the structural high. Along the NW-flank of the Al Kharrar monocline syntectonic sediment thickness is generally less than 0.5 km while along the SW-flank it thickens rapidly to nearly 1 km at the southern end of the interpreted seismic lines. This rapid southern subsidence probably continues into the north end of the Dead Sea Basin the lake's shoreline being located less than 3 km to the south. Young bifurcating faults with reverse slip components cutting the eastern part of the Al-Kharrar monocline are attributed to a positive flower structure. This pattern suggests strike slip with localized active compression northeast of the Dead Sea. It may result from local transpression between fault strands that appear to be a northward continuation of the eastern boundary fault of the Dead Sea Basin.
The structure of the Dead Sea basin
Tectonophysics, 1996
The Dead Sea basin is located along the left-lateral transform boundary between the Arabian and Sinai plates. Its structure and history are known from surface geology, drilling, seismic reflection and other geophysical data. The basin comprises a large pull-apart, almost 150 km long and mostly 8-10 km wide, which is flanked by a few kilometres wide zones of normal faulting. The basin formed at about 15 Ma or earlier, close to the beginning of the transform motion, and it reached about half its present length before the end of the Miocene. A strong negative gravity anomaly records a thick sediment basin fill: >5 km under half its length, reaching a maximum of _> 10 km. The fill includes a few km of salt (ca. 6-4 Ma) which forms several diapirs. At any one time large parts of the basin subsided simultaneously, but the site of fastest subsidence seems to have shifted northward. Sedimentation rates reached at least hundreds of metres per million years or more in the Miocene, and > 1 km/Myr in later periods.
Structure of the Dead Sea pull-apart basin from gravity analyses
Journal of Geophysical Research: Solid Earth, 1993
Analyses and modeling of gravity data in the Dead Sea pull-apart basin reveal the geometry of the basin and constrain models for its evolution. The basin is located within a valley which defines the Dead Sea transform plate boundary between Africa and Arabia. Three hundred kilometers of continuous marine gravity data, collected in a lake occupying the northern part of the basin, were integrated with land gravity data from Israel and Jordan to provide coverage to 30 km either side of the basin. Free-air and variable-density Bouguer anomaly maps, a horizontal first derivative map of the Bouguer anomaly, and gravity models of profiles across and along the basin were used with existing geological and geophysical information to infer the structure of the basin. The basin is a long (132 km), narrow (7-10 km), and deep (-<10 km) full graben which is bounded by subvertical faults along its long sides. The Bouguer anomaly along the axis of the basin decreases gradually from both the northern and southern ends, suggesting that the basin sags toward the center and is not bounded by faults at its narrow ends. The surface expression of the basin is wider at its center (<16 km) and covers the entire width of the transform valley due to the presence of shallower blocks that dip toward the basin. These blocks are interpreted to represent the widening of the basin by a passive collapse of the valley floor as the full graben deepened. The collapse was probably facilitated by movement along the normal faults that bound the transform valley. We present a model in which the geometry of the Dead Sea basin (i.e., full graben with relative along-axis symmetry) may be controlled by stretching of the entire (brittle and ductile) crust along its long axis. There is no evidence for the participation of the upper mantle in the deformation of the basin, and the Moho is not significantly elevated. The basin is probably close to being isostatically uncompensated, and thermal effects related to stretching are expected to be minimal. The amount of crustal stretching calculated from this model is 21 km and the stretching factor is 1.19. If the rate of crustal stretching is similar to the rate of relative plate motion (6 mm/yr), the basin should be-•3.5 m.y. old, in accord with geological evidence. ment discontinuities across en echelon faults in a brittleelastic medium [Rodgers, 1980; $egall and Pollard, 1980; Bilham and King, 1989]. The evolution of deep basins (deeper than 2-3 km) is expected to be more complicated as they result from either larger displacements along the fault system or from rotation of the axis of extension relative to the fault system. Furthermore, the deformation of deep 1U.S. Geological Survey,
Tectonophysics, 2002
A multi-channel seismic reflection survey consisting of 20 lines with a total length of 180 km was conducted in the Sea of Galilee. The data provide new insights into the Pliocene -Quaternary evolution of the Kinarot -Beit -Shean pull-apart basin (KBSB) along the Dead Sea transform. Two distinct zones are defined beneath the lake: (1) a graben that underlies most of the lake, bounded by steep north -south longitudinal strike-slip faults and (2) shallow pre-rift units underlying the northwestern wider part of the lake. We suggest that before approximately 4 Ma, the KBSB grew due to northward movement of the Korazim Plateau and by crustal stretching along the rift axis. Since the Pliocene ( f 4 Ma), lateral slip has been transferred from the southern segment of the basin's western marginal fault to normal faults in the Galilee, and to the eastern margin of the Korazim Plateau by the newly formed, Almagor fault, which makes a restraining bend along the transform. N -S lithospheric stretching below the KBSB has diminished and the Korazim Plateau has changed from being a detached block to a compressional saddle. A phase of rapid subsidence, and formation of a half-graben structure in the northern part of the basin approximately 1 Ma ago was coeval with major deformation in areas adjacent to the KBSB, indicating major reorganization of the plate boundary in the region. Currently, most transform motions are probably taken up along a single fault on the eastern side of the KBSB, implying that the main trough under the Sea of Galilee is in a late stage of growth as a pull-apart. D
The Tectonic Geomorphology and the Archeoseismicity of the Dead Sea Transform in Jordan Valley
2007
The Dead Sea transform (DST) extends 1000 km from the Sinai triple junction in the south to the Tauros- Zagros collision zone in Turkey in the north. In Jordan, the DST consists of three morphotectonic elements; the Wadi Araba in the south, the Dead Sea basin in the middle and the Jordan Valley in the north. The Dead Sea is a pull- apart basin that formed due to the overlap of the Wadi Araba fault (WAF) and the Jordan Valley fault (JVF). The movement along the transform is active as indicated from both the geomorphological features and from the seismic activity. The DST is a major left lateral strike slip fault that accommodates the relative motion of the Arabian plate to the east and the Sinai plate to the west, where 107 km of cumulative left lateral offset has occurred over the last 18 million years. Based on this offset, the accumulated slip rate is estimated to be 5-10 mm/yr. Based on aerial photographic analysis of the DST and earthquake catalogue information, it is suggested ...