Effective elastic thickness of the Arabian plate: Weak shield versus strong platform

Chen, Bo; Kaban, Mikhail K.; Khrepy, Sami El; Al-Arifi, Nassir

doi:10.1002/2015gl063725

Cited by 47 publications

(41 citation statements)

References 28 publications

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“…This range of values is consistent with the equivalent elastic thickness of the lithosphere determined in previous studies based on the analysis of 1-D profiles in the eastern sector of our study area (about 50 km, Snyder & Barazangi 1986;Saura et al 2015). It is also consistent with the equivalent elastic thickness mapped from the coherence between the topography and the gravity field (Chen et al 2015), which shows a gradient from about 90 km for the Arabian Platform south of the Mesopotamia basin to about 30 km beneath the Zagros.…”

Section: Implications For the Rheological Layering Of The Continentalsupporting

confidence: 92%

“…T e = 30 km when only the gravity data are used). Similarly low values of T e have also been inferred there based on the coherence between topography and gravity anomalies over the range (Zamani et al 2014;Chen et al 2015). A northward gradual decrease in T e is expected because of the bending-induced reduction of the elastic cores, and the presumably higher crustal temperatures within the range resulted from crustal thickening and vertical heat advection (e.g.…”

Section: Implications For the Rheological Layering Of The Continentalsupporting

confidence: 65%

“…In this model of flexural support, the plate is assumed to have homogeneous properties. Lateral variations of equivalent elastic thickness, T e , which may well exist at the scale of our study (Zamani et al 2014;Chen et al 2015) are thus ignored. In-plane stresses are ignored (no buckling) and non-hydrostatic basal tractions are neglected, as well as stresses due to dynamics below the lithosphere are ignored.…”

Section: F L E X U R a L B E N D I N G M O D E Lmentioning

confidence: 99%

“…Burov & Diament 1995), and could vary significantly based on its composition and thermal structure (Watts & Burov 2003;Jackson et al 2008). The coherence between topography and gravimetry anomalies at the scale of the Arabian Peninsula suggests a rather large equivalent elastic thickness beneath the Zagros foreland of about 50 km (Chen et al 2015). However, it has been suggested that the equivalent elastic thickness, T e , derived from gravity data using such a spectral method could be overestimated in areas of low topography and that an admittance technique would be more reliable.…”

Section: Introductionmentioning

confidence: 99%

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Flexural bending of the Zagros foreland basin

Pirouz¹,

Avouac²,

Gualandi³

et al. 2017

Geophysical Journal International

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S U M M A R YWe constrain and model the geometry of the Zagros foreland to assess the equivalent elastic thickness of the northern edge of the Arabian plate and the loads that have originated due to the Arabia-Eurasia collision. The Oligo-Miocene Asmari formation, and its equivalents in Iraq and Syria, is used to estimate the post-collisional subsidence as they separate passive margin sediments from the younger foreland deposits. The depth to these formations is obtained by synthesizing a large database of well logs, seismic profiles and structural sections from the Mesopotamian basin and the Persian Gulf. The foreland depth varies along strike of the Zagros wedge between 1 and 6 km. The foreland is deepest beneath the Dezful embayment, in southwest Iran, and becomes shallower towards both ends. We investigate how the geometry of the foreland relates to the range topography loading based on simple flexural models. Deflection of the Arabian plate is modelled using point load distribution and convolution technique. The results show that the foreland depth is well predicted with a flexural model which assumes loading by the basin sedimentary fill, and thickened crust of the Zagros. The model also predicts a Moho depth consistent with Free-Air anomalies over the foreland and Zagros wedge. The equivalent elastic thickness of the flexed Arabian lithosphere is estimated to be ca. 50 km. We conclude that other sources of loading of the lithosphere, either related to the density variations (e.g. due to a possible lithospheric root) or dynamic origin (e.g. due to sublithospheric mantle flow or lithospheric buckling) have a negligible influence on the foreland geometry, Moho depth and topography of the Zagros. We calculate the shortening across the Zagros assuming conservation of crustal mass during deformation, trapping of all the sediments eroded from the range in the foreland, and an initial crustal thickness of 38 km. This calculation implies a minimum of 126 ± 18 km of crustal shortening due to ophiolite obduction and post-collisional shortening.

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Section: Implications For the Rheological Layering Of The Continentalsupporting

confidence: 92%

Section: Implications For the Rheological Layering Of The Continentalsupporting

confidence: 65%

Section: F L E X U R a L B E N D I N G M O D E Lmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Flexural bending of the Zagros foreland basin

Pirouz¹,

Avouac²,

Gualandi³

et al. 2017

Geophysical Journal International

View full text Add to dashboard Cite

show abstract

“…10, profile 4), which clearly marks the boundary between the strong lithosphere in western Egypt and the weaker lithosphere in the east. This result agrees with estimations of the effective elastic thickness of the lithosphere based on the cross-spectral analysis of the gravity field (Chen et al, 2015). The seismicity behavior at the edge of the high-density lithosphere block is similar to that at the southern border of the Nile Delta (Fig.…”

Section: Fragmentation Of the Lithosphere In Egypt Based On Its Densisupporting

confidence: 87%

Density structure and isostasy of the lithosphere in Egypt and their relation to seismicity

2018

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Abstract. A joint analysis of the new satellite-terrestrial gravity field model with recent data on the crustal structure and seismic tomography was conducted to create an integrative model of the crust and upper mantle and to investigate the relation of the density structure and the isostatic state of the lithosphere to the seismicity of Egypt. We identified the distinct fragmentation of the lithosphere of Egypt in several blocks. This division is closely related to the seismicity patterns in this region. The relatively dense and strong lithosphere in the Nile Delta limits the seismic activity within this area, while earthquakes are mainly associated with the boundaries of this block. In the same way, the relatively strong lithosphere in the Isthmus of Suez and northern Mediterranean prevents the Gulf of Suez from opening further. The central part of Egypt is generally characterized by an increased density of the mantle, which extends to the Mediterranean at a depth of 100 km. This anomaly deepens southward to Gilf Kebir and eastward to the Eastern Desert. The average density of the crystalline crust is generally reduced in this zone, indicating the increased thickness of the upper crust. The low-density anomaly under the northern Red Sea is limited to 100-125 km, confirming the passive origin of the extension. Most of the earthquakes occur in the crust and uppermost mantle in this structure due to the hot and weak upper mantle underneath. Furthermore, an asymmetric lithosphere structure is observed across the northern Red Sea. The isostatic anomalies show the fragmentation of the crust of Sinai with the high-density central block. Strong variations in the isostatic anomalies are correlated with the high level of seismicity around Sinai. This tendency is also evident in the northern Red Sea, east of the Nile Valley, and in parts of the Western Desert.

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Three‐dimensional density model of the upper mantle in the Middle East: Interaction of diverse tectonic processes

et al. 2016

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We present a three‐dimensional density model of the lithosphere and upper mantle for the Middle East and surroundings based on seismic, gravity, and seismic tomography data and analyze the main factors responsible for the density variations. The gravity effect of the crust is calculated and removed from the observed field using the most recent crustal model. The residual gravity anomalies are jointly inverted with the residual topography to image the density distribution within the upper mantle. The inversion is constrained by an initial density model based on seismic tomography. The obtained density variations span in a large range (±60 kg/m3), revealing strong asymmetry in the density structure of the Arabian plate. The uppermost mantle layer in the Arabian Shield is relatively dense. However, below a depth of ~100 km we observe a strong low‐density anomaly. In contrast, the mantle density in the Arabian platform increases at the same depths. The most pronounced decrease of the mantle density occurs in the Gulf of Aden, Red Sea, and East African Rift. Underneath the northern Red Sea the low‐density anomaly is limited to the depth ~150 km, while in the southern part it is likely linked to a mantle plume. The densest mantle material is found under the South Caspian basin, which is likely associated with an eclogite body in the uppermost mantle. In the collision zones (the Zagros Belt and the Hellenic Arc), the high‐density lithosphere shows the location of the subducting plates.

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Effective elastic thickness of the Arabian plate: Weak shield versus strong platform

Cited by 47 publications

References 28 publications

Flexural bending of the Zagros foreland basin

Flexural bending of the Zagros foreland basin

Density structure and isostasy of the lithosphere in Egypt and their relation to seismicity

Three‐dimensional density model of the upper mantle in the Middle East: Interaction of diverse tectonic processes

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