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  • 1
    Language: English
    In: Basin research, 2020-08, Vol.32 (4), p.636-651
    Description: The Dead Sea is an extensional basin developing along a transform fault plate boundary. It is also a terminal salt basin. Without knowledge of precise stratigraphy, it is difficult to differentiate between the role of plate and salt tectonics on sedimentary accumulation and deformation patterns. While the environmental conditions responsible for sediment supply are reasonably constrained by previous studies on the lake margins, the current study focuses on deciphering the detailed stratigraphy across the entire northern Dead Sea basin as well as syn and post‐depositional processes. The sedimentary architecture of the late Quaternary lacustrine succession was examined by integrating 851 km of seismic reflection data from three surveys with gamma ray and velocity logs and the stratigraphic division from an ICDP borehole cored in 2010. This allowed seismic interpretation to be anchored in time across the entire basin. Key surfaces were mapped based on borehole lithology and a newly constructed synthetic seismogram. Average interval velocities were used to calculate isopach maps and spatial and temporal sedimentation rates. Results show that the Amora Formation was deposited in a pre‐existing graben bounded by two N‐S trending longitudinal faults. Both faults remained active during deposition of the late Pleistocene Samra and Lisan Formations—the eastern fault continued to bound the basin while the western fault remained blind. On‐going plate motion introduced a third longitudinal fault, increasing accommodation space westwards from the onset of deposition of the Samra Formation. During accumulation of these two formations, sedimentation rates were uniform over the lake and similar. High lake levels caused an increase in hydrostatic pressure. This led to salt withdrawal, which flowed to the south and southwest causing increased uplift of the Lisan and En Gedi diapirs and the formation of localized salt rim synclines. This induced local seismicity and slumping, resulting in an increased thickness of the Lisan succession within the lake relative to its margins. Sedimentation rates of the Holocene Ze'elim Fm were 4–5 times higher than before. The analysis presented here resolves central questions of spatial extent and timing of lithology, deposition rates and their variability across the basin, timing of faulting at and below the lake floor, and timing and extent of salt and plate tectonic phases and their effect on syn and post‐depositional processes. Plate tectonics dictated the structure of the basin, while salt tectonics and sediment accumulation were primarily responsible for its fill architecture during the timeframe examined here.
    Subject(s): lake sediments ; Dead Sea basin ; ICDP ; salt tectonics ; diapirism ; late Quaternary ; well logs ; subsidence rate
    ISSN: 0950-091X
    E-ISSN: 1365-2117
    Source: Alma/SFX Local Collection
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  • 2
    Language: English
    In: Geophysical research letters, 2015-09-16, Vol.42 (17), p.6989-6996
    Description: The Dead Sea Fault (DSF) is a 1000 km long continental transform. It forms a narrow and elongated valley with uplifted shoulders showing an east‐west asymmetry, which is not common in other continental transforms. This topography may have strongly affected the course of human history. Several papers addressed the geomorphology of the DSF, but there is still no consensus with respect to the dominant mechanism of its formation. Our thermomechanical modeling demonstrates that existence of a transform prior to the rifting predefined high strain softening on the faults in the strong upper crust and created a precursor weak zone localizing deformations in the subsequent transtensional period. Together with a slow rate of extension over the Arabian plate, they controlled a narrow asymmetric morphology of the fault. This rift pattern was enhanced by a fast deposition of evaporites from the Sedom Lagoon, which occupied the rift depression for a short time period. Key Points Existence of a transform and a slow rate of extension control a narrow asymmetric morphology of DSF A transform created a precursor weak zone localizing deformations in the later transtensional period This narrow rift pattern was enhanced by a fast deposition of evaporites from Sedom Lagoon
    Subject(s): Dead Sea Fault ; rift ; sediments ; geodynamic modeling
    ISSN: 0094-8276
    E-ISSN: 1944-8007
    Source: Alma/SFX Local Collection
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  • 3
    Language: English
    In: Journal of geophysical research. Solid earth, 2013-03, Vol.118 (3), p.1195-1202
    Description: Oceanic transform faults respond to changes in the direction of relative plate motion. Studies have shown that short‐offset transforms generally adjust with slight bends near the ridge axis, while long‐offset ones have a remarkably different behavior. The western Pacific‐Antarctic plate boundary highlights these differences. A set of previously unpublished seismic profiles, in combination with magnetic anomaly identifications, shows how across a former, ~1250 km long transform (the Emerald Fracture Zone), plate motion changes have produced a complex geometric readjustment. Three distinct sections are recognized along this plate boundary: an eastern section, characterized by parallel, multiple fault strand lineaments; a central section, shallower than the rest of the ridge system, overprinted by a mantle plume track; and a western section, organized in a cascade of short spreading axes/transform lineaments. This configuration was produced by changes that occurred since 30 Ma in the Australia‐Pacific relative plate motion, combined with a gradual clockwise change in Pacific‐Antarctic plate motion. These events caused extension along the former Emerald Fracture Zone, originally linking the Pacific‐Antarctic spreading ridge system with the Southeast Indian ridge. Then an intra‐transform propagating ridge started to develop in response to a ~6 Ma change in the Pacific‐Antarctic spreading direction. The close proximity of the Euler poles of rotation amplified the effects of the geometric readjustments that occurred along the transform system. This analysis shows that when a long‐offset transform older than 20 Ma is pulled apart by changes in spreading velocity vectors, it responds with the development of multiple discrete, parallel fault strands, whereas in younger lithosphere, locally modified by thermal anisotropies, tensional stresses generate an array of spreading axes offset by closely spaced transforms. Key Points Long‐offset transforms respond to plate motion changes with multiple strands In young lithosphere, plate motion changes produce intratransform ridges Main tectonic causes can be invoked for plate boundary reorganizations
    Subject(s): Pacific-Antarctic ridge ; Pacific‐Antarctic ridge
    ISSN: 2169-9313
    E-ISSN: 2169-9356
    Source: Alma/SFX Local Collection
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  • 4
    Language: English
    In: Journal of Geophysical Research: Solid Earth, 2006-08-11, Vol.111 (B8), p.B08402-n/a
    Description: The southward propagation of the East Africa rift presents an opportunity to study plate boundary formation. We tabulate orientation data which confirm the province of NW‐SE directed most compressive horizontal principal stress (“Wegener stress anomaly”) earlier tentatively attributed to ridge push. We also collect information on stress “regime,” described by the associated Andersonian fault type(s). We use thin shell finite element models with realistic rheology to test three causes of stress: (1) lateral variations in density moment, (2) resistance of unbroken lithosphere to relative plate rotation, and (3) stress concentration ahead of a crack tip. Models with stress due primarily to variations in density moment are unsuccessful in their predictions (59–73% incorrect regimes; 32–40° azimuth errors). Models in which Africa‐Somalia spreading is regulated at realistic rates by remote boundary conditions are more accurate (18–41% incorrect regimes; 25–35° azimuth errors). Treating the East Africa rift as a frictionless crack degrades the fit in either case. Apparently, the Wegener stress anomaly is caused primarily by resistance to the relative rotation between the Somalia and Africa plates. The East Africa rift north of 21°S may be weakened by strain but has residual friction ≥0.1. Greater strength of oceanic lithosphere is likely to cause stress increases, reorientations, and regime changes offshore. The predicted strain rate map has high rates along the rift, curving at 12°S into a western arc through Angola‐Namibia‐South Africa. Seismic hazard in Namibia may be greater than the instrumental catalog suggests. However, a number of unfit data indicate that these models represent only a first step.
    Subject(s): Continental tectonics ; Stresses ; crust and lithosphere ; Seismology ; Marine Geology and Geophysics ; Tectonophysics ; Computational Geophysics ; Submarine tectonics and volcanism ; extensional ; Modeling ; Seismicity and tectonics ; lithosphere ; stress ; extension ; Earth, ocean, space ; Earth sciences ; Exact sciences and technology
    ISSN: 0148-0227
    E-ISSN: 2156-2202
    Source: Wiley Online Library All Backfiles
    Source: Alma/SFX Local Collection
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  • 5
    Language: English
    In: Sedimentology, 2015-02, Vol.62 (2), p.516-540
    Description: Quaternary reef development and demise have been shown to correspond to worldwide sea‐level fluctuations and related environmental changes, yet the mechanisms and rates affecting this relationship are not well resolved. A set of high‐resolution seismic reflection and multibeam bathymetric data were interpreted. Six distinct systems of relict fringing reefs embedded within the sedimentary cover of the northern shelf of the Gulf of Elat/Aqaba were identified. The two uppermost relict fringing reefs are also exposed on the sea floor in water depths of ca 20 m and ca 60 m, along the north‐western corner of the northern Gulf of Elat/Aqaba and sub‐parallel to the current northern coast, respectively. Two other relict fringing reefs are laterally correlated to each of the last two transgressive cycles, and are inferred to have formed during decelerations in sea‐level rise during the last two deglaciations. These reefs and the units to which they are laterally correlated portray a repeating stratigraphic pattern of reef development during deposition of seismically homogeneous sediment and an ensuing demise during deposition of heterogeneous sediment. Correlation of the reef stratigraphy with rates of Late Quaternary sea‐level rise and a sediment accumulation rate from one shelf core provide age estimations for the seismic stratigraphy. Two phases of fringing reef generation occurred during the last deglaciation (since ca 18 ka); the older reef probably developed between 12·8 ka and 11·5 ka at ca 60 m below present sea‐level and the younger reef after 8·4 to 8·0 ka at ca 20 m below present sea‐level. These last two phases of reef generation are separated by a lobate seismic unit that is interpreted as fluvial‐deltaic deposits that backstepped across the shelf during the Early Holocene transgression. Results suggest that fringing reefs evolved along the northern shelf of the Gulf of Elat/Aqaba only during relative decelerations in sea‐level rise, contemporaneous with low input of terrigenous sediment and probably during a period of aridity. At present, no fringing reef grows along the northern coast of the Gulf of Elat/Aqaba, suggesting that these relatively arid periods may have been drier than Recent. The pattern of slowdown in sea‐level rise contemporaneous with conditions of increased aridity seems to have repeated during the last two sea‐level rises, approximately at the same sea‐levels, suggesting a common mechanism of short (millennium‐scale) phases of eustatic and climatic alteration during deglaciations.
    Subject(s): Climate change ; fringing reef ; sequence stratigraphy ; high-resolution ; Quaternary ; seismic reflection ; sea-level ; seismic stratigraphy ; sea‐level ; high‐resolution ; Reefs ; Climatic changes ; Sediments (Geology)
    ISSN: 0037-0746
    E-ISSN: 1365-3091
    Source: Alma/SFX Local Collection
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  • 6
    Language: English
    In: The Journal of geology, 2010-05, Vol.118 (3), p.261-276
    Description: The Jericho fault is considered to be the main active fault in the northern Dead Sea–lower Jordan Valley. In previous studies it has been identified by a prominent linear topographic escarpment that is thought to be the surface expression of this fault on land north of the Dead Sea. In this study, the paleoseismic natures of the escarpment and the fault were examined. Seismic activity was investigated in a series of three trenches excavated south of the fault trace on the surface. These trenches show evidence for Late Holocene faulting. A fourth trench excavated 300 m farther to the south exposed continuous, finely laminated marl from the ∼80‐ka Samra Formation at a depth of 2–0.6 m below the surface, with no evidence of faulting. This could suggest that the fault on land is segmented and that the nature of its activity changes from north to south toward the lake. Indeed, the continuation of this fault under the waters of the Dead Sea reveals active faulting along a sharp, segmented, linear bathymetric break, where the steep margin slope on the west meets the flat lake bottom. Evidence of drastic climatic changes and erosion are present in all trenches that were excavated, indicating that the prominent escarpment may in part be an erosional feature, perhaps formed by incision of an ancient Jordan River or along a Holocene lakeshore. A channel fill of a lacustrine nature that followed a period of erosion is interpreted as a high stand of the Dead Sea, which is contemporaneous with the Younger Dryas cooling period.
    Subject(s): Fault lines ; Escarpments ; Cliffs ; Trenches ; Earthquakes ; Shales ; Lakes ; Sediments ; Tectonics ; Perceptual localization ; Faults (Geology) ; Geomorphology ; Research ; Paleoseismology ; Tectonics (Geology)
    ISSN: 0022-1376
    E-ISSN: 1537-5269
    Source: University of Chicago Press Journals (Full run)
    Source: Academic Search Ultimate
    Source: JSTOR Arts & Sciences VI
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  • 7
    Language: English
    In: Tectonics (Washington, D.C.), 2003-12-16, Vol.22 (6), p.1076-n/a
    Description: Multichannel seismic reflection profiles, gravity measurements, and bathymetric soundings, in conjunction with field geological reconnaissance and remote sensing images, reveal with unprecedented detail the morphostructure of a major segment of the South America–Scotia plate boundary in the Tierra del Fuego region. This segment, known as the Magallanes‐Fagnano fault system, is a continental transform margin arranged in an en echelon geometry, along which prominent asymmetric basins were developed. Data acquired off the Atlantic coast of Isla Grande (the main island of Tierra del Fuego), in its central and eastern part, and in the central and western Magallanes Strait image the surface and subsurface structure of the transform fault and its associated basins. The Magallanes‐Fagnano fault system is composed of distinct tectonic lineaments that are segments of the transform system and are represented by mostly near‐vertical faults. In the Atlantic sector, the fault system trends broadly N70°E and seems to be composed by a single master fault, along which a highly asymmetric basin has formed. At around 63°W, the fault terminates by splaying into secondary normal faults that dissipate the horizontal displacement along the system. In the central eastern part of Isla Grande, the fault segments have been principally identified from analyses of remote sensing images on the basis of their morphological expression. These segments are located within river valleys and are generally associated with localized gravity minima. Lago Fagnano, a 105‐km‐long, E‐W trending depression, is a large, mostly asymmetric pull‐apart basin developed within the principal displacement zone of the Magallanes‐Fagnano fault system. Restraining bends and overlapping step‐over geometry characterize the central part of the Magallanes Strait. Along the western part of the fault system, in the vicinity of the Pacific entrance of the Magallanes Strait, asymmetric sedimentary basins have also developed. The sedimentary architecture of the basins formed within the principal displacement zone of the fault, in which the thick end of the depositional wedge abuts the transform segment, suggest simultaneous strike‐slip motion and transform‐normal extension, a common feature found in other continental transtensional environments. Strike‐slip faulting in the Tierra del Fuego region is also documented along other prominent lineaments which parallel the Magallanes‐Fagnano fault system. Along at least two of these lineaments, characterized by a remarkable morphological expression, widespread Quaternary activity occurs. The present‐day motion between the South America and Scotia plates is slow (〈5 mm/yr). Also the modern seismicity monitored in the Tierra del Fuego region is low (individual events 〈3.5 in magnitude). The low seismicity may be explained by the slow relative motion between plates and may be further affected by slip partitioning along the different segments which make up the Magallanes‐Fagnano fault array, and along the subsidiary wrench lineaments that traverse the region.
    Subject(s): Local crustal structure ; Plate motions—present and recent ; Plate boundary—general ; Structural Geology ; Remote sensing ; Tectonophysics ; remote sensing images ; Tierra del Fuego region ; geophysical data ; strike-slip tectonics ; Magallanes-Fagnano fault system ; Magallanes‐Fagnano fault system ; strike‐slip tectonics
    ISSN: 0278-7407
    E-ISSN: 1944-9194
    Source: Wiley Online Library All Backfiles
    Source: Alma/SFX Local Collection
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  • 8
    Language: English
    In: Geophysical journal international, 2010-04, Vol.181 (1), p.185-197
    Description: We address the mechanism of sedimentary basin formation along strike-slip fault systems with 3-D numerical simulations based on a continuum damage rheology model. The formation of these basins is usually explained by a pull-apart mechanism that predicts a rhomb-shaped basin geometry bounded by two longitudinal strike-slip faults and two transverse listric faults. Significant ductile deformation of the lower crust and upper mantle associated with basin growth requires normal or elevated heat flux. The Dead Sea continental transform is associated with some of the larger and unusually deep basins, among which the southern Dead Sea is the deepest. The heat flow in the Dead Sea basin is anomalously low and it is associated with deep seismicity. Moreover, the basin is bounded by deep transverse normal faults rather than the listric faults required by the pull-apart model. Hence, the formation of the basin cannot be explained by the existing pull-apart model. Ben-Avraham and Schubert proposed an alternative conceptual model for the formation of the deepest basin at the southern Dead Sea. They suggested that an isolated block of lithosphere has dropped into the mantle. We simulate the formation of this and other deep basins along the Dead Sea fault and demonstrate that the ‘drop down’ mechanism of the Dead Sea basin formation suggested by Ben-Avraham & Schubert is possible. Density heterogeneities formed in the crust or upper mantle during a previous stage of regional magmatism, drop into the upper mantle when strike-slip faults are created and detach them from the surrounding lithosphere. The simulations indicate that the resulting basin is rhomb-shaped and that with time it grows by the addition of distinct segments to its edges. The proposed mechanism could account for the formation and evolution of large sedimentary basins along other strike-slip fault systems, such as the San Andreas fault and other continental transform faults.
    Subject(s): Numerical solutions ; Continental tectonics: strike-slip and transform ; and modelling ; Mechanics ; Rheology: crust and lithosphere ; Sedimentary basin processes ; Fractures and faults ; theory ; Mechanics, theory, and modelling ; Continental tectonics: strike‐slip and transform ; Earth ; Crust ; Analysis ; Lithosphere ; Geophysics ; Tectonics (Geology) ; Strike-slip faults (Geology) ; Sedimentary basins ; Transform faults ; Mantle
    ISSN: 0956-540X
    E-ISSN: 1365-246X
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
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  • 9
    Language: English
    In: Annual review of earth and planetary sciences, 2008-05, Vol.36 (1), p.357-387
    Subject(s): Geology ; Research
    ISSN: 0084-6597
    E-ISSN: 1545-4495
    Source: Annual Reviews Complete A-Z List
    Source: Electronic Back Volume Collection (EBVC)
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  • 10
    Language: English
    In: Journal of geophysical research. Solid earth, 2014-12, Vol.119 (12), p.9183-9205
    Description: The northern Gulf of Elat/Aqaba is located in the transition between the deep marine basins of the gulf and the shallow onland basins of the Arava Valley. Interpretation of 500 km of high‐resolution seismic reflection data collected across the northern shelf reveals the tectonic structure and evolution of this transition. Six NNE‐trending faults and one E‐W trending transverse fault are mapped. Slip rates are calculated based on measured offsets and age determination based on a radiocarbon‐calibrated sedimentation rate and a Quaternary age model. The most active fault is the Evrona Fault that absorbs most of the left lateral slip within the basin with an average sinistral slip rate of 0.7 ± 0.3 mm/yr through the Late Pleistocene and 2.3–3.4 mm/yr during the Holocene. Two intrabasin faults east of the Evrona Fault that have been inactive for the last several tens of thousands of years were mapped, and motion from these faults has likely transferred to the Evrona Fault. The basin is flanked on the west by the Elat Fault and on the east by the Aqaba Fault. Both faults are marked by large bathymetric escarpments. Based on displaced seismic reflectors, we calculate a Holocene vertical slip rate of 1.0 ± 0.2 and 0.4 ± 0.1 mm/yr for the Elat and Aqaba Faults, respectively. The geometry, slip rates, and slip history of the northern Gulf of Elat/Aqaba faults show that during the Late Pleistocene several intrabasin faults became dominant across the basin but that during the Holocene the Evrona Fault accommodates most of the strike slip. Key Points The study reveals six intrabasin north trending faults and one transverse faultThe Evrona strike‐slip fault occupies most of the Holocene left lateral slipThe northern GEA basin is in an advanced stage of evolution
    Subject(s): fault ; Gulf of Aqaba ; basin ; Transform ; Dead Sea ; tectonic
    ISSN: 2169-9313
    E-ISSN: 2169-9356
    Source: Alma/SFX Local Collection
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