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Iyad Al Gharib - One of the best experts on this subject based on the ideXlab platform.
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volcano tectonic evolution of the northern part of the Arabian Plate in the light of new k ar ages and remote sensing harrat ash shaam volcanic province syria
Tectonophysics, 2012Co-Authors: Mohamad Amer Al Kwatli, Pierre Yves Gillot, Hermann Zeyen, Anthony Hildenbrand, Iyad Al GharibAbstract:Abstract The Harrat Ash Shaam volcanic province (HASV) is the largest volcanic field in the Arabian Plate. It developed during the Cenozoic close to the southern part of Dead Sea fault system and has been linked to the tectonic evolution of the Red Sea rifting since the early Oligocene. The HASV is an ideal environment to study volcanism adjacent to a strike–slip fault (the Dead Sea fault system) and constrain the development of regional deformation along such lithospheric structures. We here present a morpho-structural analysis based on digital elevation data coupled with remote sensing observations and new K–Ar ages on fresh separated groundmass which allow us to propose a new volcano-tectonic model of the HASV. From Landsat7 Enhanced Thematic Mapper plus (ETM +) and SRTM data, we recognize more than 350 monogenetic volcanic cones grouped in three main clusters. Topographical variations between these clusters are interpreted as reflecting different volcanic phases. The new ages measured here range between 7.13 ± 0.10 Ma and 0.056 ± 0.009 Ma. Together with previous geochronological data, they reveal two main periods of volcanic activity. The first period lasted from late Oligocene up to early-middle Miocene (26–16 Ma), and the second period has been active since 13 Ma, indicating a gap of volcanic activity between ~ 16 and ~ 13 Ma. The volcano-tectonic evolution model suggests two different extensional styles, “en-echelon” rifting during the first period, and counterclockwise rotation during the second one. Alternative to the Afar plume hypothesis, a thinned lithosphere underneath the HASV as supported by geophysical modeling, can explain magma genesis in the northern part of the Arabian Plate.
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Volcano-tectonic evolution of the northern part of the Arabian Plate in the light of new K–Ar ages and remote sensing: Harrat Ash Shaam volcanic province (Syria)
Tectonophysics, 2012Co-Authors: Mohamad Amer Al Kwatli, Pierre Yves Gillot, Hermann Zeyen, Anthony Hildenbrand, Iyad Al GharibAbstract:Abstract The Harrat Ash Shaam volcanic province (HASV) is the largest volcanic field in the Arabian Plate. It developed during the Cenozoic close to the southern part of Dead Sea fault system and has been linked to the tectonic evolution of the Red Sea rifting since the early Oligocene. The HASV is an ideal environment to study volcanism adjacent to a strike–slip fault (the Dead Sea fault system) and constrain the development of regional deformation along such lithospheric structures. We here present a morpho-structural analysis based on digital elevation data coupled with remote sensing observations and new K–Ar ages on fresh separated groundmass which allow us to propose a new volcano-tectonic model of the HASV. From Landsat7 Enhanced Thematic Mapper plus (ETM +) and SRTM data, we recognize more than 350 monogenetic volcanic cones grouped in three main clusters. Topographical variations between these clusters are interpreted as reflecting different volcanic phases. The new ages measured here range between 7.13 ± 0.10 Ma and 0.056 ± 0.009 Ma. Together with previous geochronological data, they reveal two main periods of volcanic activity. The first period lasted from late Oligocene up to early-middle Miocene (26–16 Ma), and the second period has been active since 13 Ma, indicating a gap of volcanic activity between ~ 16 and ~ 13 Ma. The volcano-tectonic evolution model suggests two different extensional styles, “en-echelon” rifting during the first period, and counterclockwise rotation during the second one. Alternative to the Afar plume hypothesis, a thinned lithosphere underneath the HASV as supported by geophysical modeling, can explain magma genesis in the northern part of the Arabian Plate.
G Steinitz - One of the best experts on this subject based on the ideXlab platform.
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new k ar ages of basalts from the harrat ash shaam volcanic field in jordan implications for the span and duration of the upper mantle upwelling beneath the western Arabian Plate
Geology, 2001Co-Authors: Shimon Ilani, Yehudit Harlavan, Khalid Tarawneh, I Rabba, Ram Weinberger, Khalil M Ibrahim, Sergiu Peltz, G SteinitzAbstract:The volcanism in the western Arabian Plate extends from the Red Sea through the Harrat Ash Shaam system to western Syria, as far north as the Bitlis suture in the Taurides. The Harrat Ash Shaam volcanic system in Jordan consists of northwest-trending dikes and a volcanic field that together encompass a width of 220 km. In terms of width, direction, and age of the main volcanic phases, the system is similar to the Red Sea dike belt. About 130 new K-Ar age determinations show that the ages of the Harrat Ash Shaam system (dikes and flows) range from Oligocene to Quaternary. However, there is a distinct gap in the ages between ∼22 and 13 Ma. This gap coincides with an apparent decrease in volcanism in the Red Sea region from around 20 to 12 Ma. We interpret this 9 m.y. gap as a quiescent period interrupting the volcanic activity in the region and suggest that from ∼22 to 13 Ma, tectonic activity in the Arabian Plate was mainly restricted to the Red Sea region. A renewal of volcanism along the western margins of the Arabian Plate at 13 Ma was very likely associated with the sinistral movement along the north-trending Dead Sea transform. This renewal of volcanism and tectonic activity may reflect the emergence of upper-mantle upwelling beneath the western Arabian Plate at that time.
Mohamad Amer Al Kwatli - One of the best experts on this subject based on the ideXlab platform.
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morpho structural analysis of harrat al sham volcanic field Arabian Plate syria jordan and saudi arabia methodology and application
Arabian Journal of Geosciences, 2015Co-Authors: Mohamad Amer Al Kwatli, Pierre Gillot, Jean Claude Lefevre, A HildenbrandAbstract:We present here a digital methodology aimed at identifying the morphometry of monogenic volcanic cones including edifice height, slope angle, and volume. We recognize more than 800 monogenic volcanic cones from the Harrat Ash Shaam volcanic province (HASV, northern Arabian Plate) to the north of the Arabian Plate by using Landsat7 Enhanced Thematic Mapper plus and digital elevation models (Shuttle Radar Topography Mission, SRTM data). Our results show that the volcanic cones fall into six clusters, each one having a NW-SE orientation parallel to the Red Sea rifting. The density of the cones is most likely controlled by fissure distribution and a possible rotation in the HASV lithospheric block, rather than by the age of the volcanic activity. Interaction with crustal lithologies also plays a negligible role during magma migration. However, the morphology of the monogenic volcanic cones appears to be significantly modified by erosion processes, and both the height and slope of the various cones thus can be used to estimate their relative ages. From such morphological criteria, HASV monogenetic volcanoes in Jordan and Saudi Arabia are older than those in the Golan Heights and the Jabal Al Arab Mountain in Syria, thus, supporting the hypothesis of a northward migration of the recent explosive activity. Our new data, together with the available sediment thickness data, give rise to a new volcano-tectonic interpretation. We show that variations in the cumulative volume of monogenic volcanic cones in several zones of the study area can be related with the sediment thickness (basement depth), and therefore, we propose that the sediment thickness most likely affects the properties of magma before eruption. The reactivation of a deep previous fault perhaps also explains the higher volume of monogenic volcanic cones, focused along a well-defined alignment. This study, thus, gives insight into the relations between sediment thickness, the volcanism, and tectonics. Our results based on new digital treatment of remote sensing data are in overall good agreement with the volcano-tectonic evolution of HASV. This allows us to recommend this methodology as a potential tool to study volcanic cones of other inaccessible regions, either on Earth or other terrestrial planets.
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volcano tectonic evolution of the northern part of the Arabian Plate in the light of new k ar ages and remote sensing harrat ash shaam volcanic province syria
Tectonophysics, 2012Co-Authors: Mohamad Amer Al Kwatli, Pierre Yves Gillot, Hermann Zeyen, Anthony Hildenbrand, Iyad Al GharibAbstract:Abstract The Harrat Ash Shaam volcanic province (HASV) is the largest volcanic field in the Arabian Plate. It developed during the Cenozoic close to the southern part of Dead Sea fault system and has been linked to the tectonic evolution of the Red Sea rifting since the early Oligocene. The HASV is an ideal environment to study volcanism adjacent to a strike–slip fault (the Dead Sea fault system) and constrain the development of regional deformation along such lithospheric structures. We here present a morpho-structural analysis based on digital elevation data coupled with remote sensing observations and new K–Ar ages on fresh separated groundmass which allow us to propose a new volcano-tectonic model of the HASV. From Landsat7 Enhanced Thematic Mapper plus (ETM +) and SRTM data, we recognize more than 350 monogenetic volcanic cones grouped in three main clusters. Topographical variations between these clusters are interpreted as reflecting different volcanic phases. The new ages measured here range between 7.13 ± 0.10 Ma and 0.056 ± 0.009 Ma. Together with previous geochronological data, they reveal two main periods of volcanic activity. The first period lasted from late Oligocene up to early-middle Miocene (26–16 Ma), and the second period has been active since 13 Ma, indicating a gap of volcanic activity between ~ 16 and ~ 13 Ma. The volcano-tectonic evolution model suggests two different extensional styles, “en-echelon” rifting during the first period, and counterclockwise rotation during the second one. Alternative to the Afar plume hypothesis, a thinned lithosphere underneath the HASV as supported by geophysical modeling, can explain magma genesis in the northern part of the Arabian Plate.
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Volcano-tectonic evolution of the northern part of the Arabian Plate in the light of new K–Ar ages and remote sensing: Harrat Ash Shaam volcanic province (Syria)
Tectonophysics, 2012Co-Authors: Mohamad Amer Al Kwatli, Pierre Yves Gillot, Hermann Zeyen, Anthony Hildenbrand, Iyad Al GharibAbstract:Abstract The Harrat Ash Shaam volcanic province (HASV) is the largest volcanic field in the Arabian Plate. It developed during the Cenozoic close to the southern part of Dead Sea fault system and has been linked to the tectonic evolution of the Red Sea rifting since the early Oligocene. The HASV is an ideal environment to study volcanism adjacent to a strike–slip fault (the Dead Sea fault system) and constrain the development of regional deformation along such lithospheric structures. We here present a morpho-structural analysis based on digital elevation data coupled with remote sensing observations and new K–Ar ages on fresh separated groundmass which allow us to propose a new volcano-tectonic model of the HASV. From Landsat7 Enhanced Thematic Mapper plus (ETM +) and SRTM data, we recognize more than 350 monogenetic volcanic cones grouped in three main clusters. Topographical variations between these clusters are interpreted as reflecting different volcanic phases. The new ages measured here range between 7.13 ± 0.10 Ma and 0.056 ± 0.009 Ma. Together with previous geochronological data, they reveal two main periods of volcanic activity. The first period lasted from late Oligocene up to early-middle Miocene (26–16 Ma), and the second period has been active since 13 Ma, indicating a gap of volcanic activity between ~ 16 and ~ 13 Ma. The volcano-tectonic evolution model suggests two different extensional styles, “en-echelon” rifting during the first period, and counterclockwise rotation during the second one. Alternative to the Afar plume hypothesis, a thinned lithosphere underneath the HASV as supported by geophysical modeling, can explain magma genesis in the northern part of the Arabian Plate.
Khalil M Ibrahim - One of the best experts on this subject based on the ideXlab platform.
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petrogenesis of the largest intraPlate volcanic field on the Arabian Plate jordan a mixed lithosphere asthenosphere source activated by lithospheric extension
Journal of Petrology, 2003Co-Authors: Julia E Shaw, Joel A Baker, Martin Menzies, M F Thirlwall, Khalil M IbrahimAbstract:Miocene to Recent volcanism in northwestern Arabia produced the largest intraPlate volcanic field on the Arabian Plate (Harrat Ash Shaam, Jordan). The chemically and isotopically diverse volcanic field comprises mafic alkali basalts and basanites. The magmas underwent limited fractional crystallization of ol cpx plag and rare samples have assimilated up to 20% of Late Proterozoic crust en route to the surface. However, there are subtle Sr±Nd±Pb isotopic variations (Sr/Sr 0 70305±0 70377, Nd/Nd 0 51297±0 51285, Pb/ Pb 18 8±19 2), which exhibit marked correlations with major elements, incompatible trace element ratios and abundances in relatively primitive basalts (MgO 48 5 wt %), and cannot be explained by fractional crystallization and crustal contamination alone. Instead, the data require polybaric melting of heterogeneous sources. Semi-quantitative melt modelling suggests that this heterogeneity is the result of small degree melts (2±5%) from spineland garnet-facies mantle, inferred to be shallowArabian lithosphere, thatmixedwith smaller degreemelts (51%) from a predominantly deep garnet-bearing asthenospheric(?) source with ocean island basalt characteristics. The latter may be a ubiquitous part of the asthenosphere but is preferentially tapped at small degrees of partial melting. Volcanism in Jordan appears to be the result of melting lithospheric mantle in response to lithospheric extension. With time, thinning of the lithosphere allowed progressively deeper mantle (asthenosphere?) to be activated and melts from this to mix with the shallower lithospheric mantle melts. Although Jordanian intraPlate volcanism is isotopically similar to examples of Late Cenozoic volcanism throughout the Arabian peninsula (Israel, Saudi Arabia), subtle chemical and isotopic differences between Yemen and Jordan intraPlate volcanism suggest that the Afar plume has not been channelled northwestwards beneath the Arabian Plate and played no role in producing the northern Saudi Arabian and Jordan intraPlate volcanic fields.
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new k ar ages of basalts from the harrat ash shaam volcanic field in jordan implications for the span and duration of the upper mantle upwelling beneath the western Arabian Plate
Geology, 2001Co-Authors: Shimon Ilani, Yehudit Harlavan, Khalid Tarawneh, I Rabba, Ram Weinberger, Khalil M Ibrahim, Sergiu Peltz, G SteinitzAbstract:The volcanism in the western Arabian Plate extends from the Red Sea through the Harrat Ash Shaam system to western Syria, as far north as the Bitlis suture in the Taurides. The Harrat Ash Shaam volcanic system in Jordan consists of northwest-trending dikes and a volcanic field that together encompass a width of 220 km. In terms of width, direction, and age of the main volcanic phases, the system is similar to the Red Sea dike belt. About 130 new K-Ar age determinations show that the ages of the Harrat Ash Shaam system (dikes and flows) range from Oligocene to Quaternary. However, there is a distinct gap in the ages between ∼22 and 13 Ma. This gap coincides with an apparent decrease in volcanism in the Red Sea region from around 20 to 12 Ma. We interpret this 9 m.y. gap as a quiescent period interrupting the volcanic activity in the region and suggest that from ∼22 to 13 Ma, tectonic activity in the Arabian Plate was mainly restricted to the Red Sea region. A renewal of volcanism along the western margins of the Arabian Plate at 13 Ma was very likely associated with the sinistral movement along the north-trending Dead Sea transform. This renewal of volcanism and tectonic activity may reflect the emergence of upper-mantle upwelling beneath the western Arabian Plate at that time.
Nassir Alarifi - One of the best experts on this subject based on the ideXlab platform.
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strength and elastic thickness variations in the Arabian Plate a combination of temperature composition and strain rates of the lithosphere
Tectonophysics, 2017Co-Authors: Magdala Tesauro, Mikhail K Kaban, Alexey G Petrunin, Sami El Khrepy, Nassir AlarifiAbstract:The Arabian Plate shows a strong asymmetry between its Shield and Platform, in terms of topography, seismic velocity and density structure of the upper mantle. This asymmetry also results in significant rheological differences between these blocks, as revealed by the effective elastic thickness (EET) estimates, obtained using a spectral gravity method. However, these estimates may be biased due to various factors. Therefore, other approaches based on a direct rheological modeling of the lithospheric structure should be employed to verify these results. In this study, we use a recent model of the lithosphere, based on an integrative interpretation of the gravity field and seismic tomography, to correct an initial thermal model obtained from the inversion of seismic velocity, assuming a uniform composition. The results are used together with the most recent crustal model of the Arabian Plate to construct two alternative models of strength and EET of the lithosphere. The first model (Model I) assumes a constant value of 10− 15 s− 1 for the strain rates. In the second model (Model II), we used the strain rates obtained from a global mantle flow model. Model I confirms the asymmetry in the rigidity of the Shield and Platform. In contrast, Model II shows that the influence of the variable strain rates causes a significant increase in the strength and EET of the central and eastern part of the Shield and in contrast to previous studies, reveals that most of the Arabian Plate is a long-term stable tectonic feature, predominantly characterized by large EET values (≥ 70 km).
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importance of the decompensative correction of the gravity field for study of the upper crust application to the Arabian Plate and surroundings
Pure and Applied Geophysics, 2017Co-Authors: Mikhail K Kaban, Sami El Khrepy, Nassir AlarifiAbstract:The isostatic correction represents one of the most useful “geological” reduction methods of the gravity field. With this correction it is possible to remove a significant part of the effect of deep density heterogeneity, which dominates in the Bouguer gravity anomalies. However, even this reduction does not show the full gravity effect of unknown anomalies in the upper crust since their impact is substantially reduced by the isostatic compensation. We analyze a so-called decompensative correction of the isostatic anomalies, which provides a possibility to separate these effects. It was demonstrated that this correction is very significant at the mid-range wavelengths and may exceed 100 m/s2 (mGal), therefore ignoring this effect would lead to wrong conclusions about the upper crust structure. At the same time, the decompensative correction is very sensitive to the compensation depth and effective elastic thickness of the lithosphere. Therefore, these parameters should be properly determined based on other studies. Based on this technique, we estimate the decompensative correction for the Arabian Plate and surrounding regions. The amplitude of the decompensative anomalies reaches ±250 m/s2 10−5 (mGal), evidencing for both, large density anomalies of the upper crust (including sediments) and strong isostatic disturbances of the lithosphere. These results improve the knowledge about the crustal structure in the Middle East.
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isostatic model and isostatic gravity anomalies of the Arabian Plate and surroundings
Pure and Applied Geophysics, 2016Co-Authors: Mikhail K Kaban, Sami El Khrepy, Nassir AlarifiAbstract:The isostatic modeling represents one of the most useful “geological” reduction methods of the gravity field. With the isostatic correction, it is possible to remove a significant part of the effect of deep density heterogeneity, which dominates in the Bouguer gravity anomalies. Although there exist several isostatic compensation schemes, it is usually supposed that a choice of the model is not an important factor to first order, since the total weight of compensating masses remains the same. We compare two alternative models for the Arabian Plate and surrounding area. The Airy model gives very significant regional isostatic anomalies, which cannot be explained by the upper crust structure or disturbances of the isostatic equilibrium. Also, the predicted “isostatic” Moho is very different from existing seismic observations. The second isostatic model includes the Moho, which is based on seismic determinations. Additional compensation is provided by density variations within the lithosphere (chiefly in the upper mantle). According to this model, the upper mantle under the Arabian Shield is less dense than under the Platform. In the Arabian platform, the maximum density coincides with the Rub’ al Khali, one of the richest oil basin in the world. This finding agrees with previous studies, showing that such basins are often underlain by dense mantle, possibly related to an eclogite layer that has caused their subsidence. The mantle density variations might be also a result of variations of the lithosphere thickness. With the combined isostatic model, it is possible to minimize regional anomalies over the Arabian Plate. The residual local anomalies correspond well to tectonic structure of the Plate. Still very significant anomalies, showing isostatic disturbances of the lithosphere, are associated with the Zagros fold belt, the collision zone of the Arabian and Eurasian Plates.
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effective elastic thickness of the Arabian Plate weak shield versus strong platform
Geophysical Research Letters, 2015Co-Authors: Bo Chen, Mikhail K Kaban, Sami El Khrepy, Nassir AlarifiAbstract:The fan wavelet method has been employed to calculate high-resolution maps of variations of the effective elastic thickness (EET) for the Arabian Plate and surroundings. As the initial data, we use high-resolution gravity field, topography, and recent models of sedimentary basins. The western part of the Plate is generally characterized by low to midvalues of EET (10–30 km) while the eastern one by high values (50 km and more in the core). This finding confirms that the pronounced asymmetry of the Plate is rather associated with fundamental structural differences of the lithosphere than with a forced tilt of the Plate due to the rifting in the west-southwest and subduction in the northeast. Therefore, the high topography in the western part of the Plate is likely supported by relatively hot mantle that is also responsible for the decrease of EET. These results are generally in agreement with recent seismic tomography models.
