3D density model of the upper mantle of Asia based on inversion of gravity and seismic tomography data

Kaban, Mikhail K.; Stolk, W.; Tesauro, Magdala; Khrepy, Sami El; Al-Arifi, Nassir; Beekman, F.; Cloetingh, S.A.P.L.

doi:10.1002/2016gc006458

Cited by 51 publications

(92 citation statements)

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“…In this section we describe a general approach for the integrative analysis of gravity and other geophysical data that was developed and applied previously for Europe, North America, and some parts of Asia (Kaban et al, , 2014a(Kaban et al, , 2016a. All details on the methods and datasets used will be provided in the following sections.…”

Section: General Modeling Approachmentioning

confidence: 99%

“…For this, the S-wave vertical profiles of Hosny and Nyblade (2016) were converted to Vp using the Vp / Vs ratios provided. The limited amounts of seismic determinations do not provide the possibility to construct a multilayer model; however, for the gravity calculations, average values are sufficient to estimate the cumulative effect of the crystalline crust (Kaban et al, 2016a). The interpolated data were merged with basic regional models (Fig.…”

Section: Model Of the Crustmentioning

confidence: 99%

“…A complete description of this technique can be found in Tesauro et al (2014) and Kaban et al (2016a). Three slices of density variations for the depths 100, 150, and 200 km are shown in Fig.…”

Section: Initial Density Model Of the Upper Mantlementioning

confidence: 99%

“…4). As already mentioned, we also removed the effect of the deep mantle heterogeneity below 325 km based on a global dynamic model described in Kaban et al (2015Kaban et al ( , 2016a). This depth is chosen based on our previous studies as the depth, which exceeds the maximal depth of the lithospheric roots.…”

Section: Residual Mantle Gravity Anomalies and Residual Topographymentioning

confidence: 99%

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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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Section: General Modeling Approachmentioning

confidence: 99%

Section: Model Of the Crustmentioning

confidence: 99%

Section: Initial Density Model Of the Upper Mantlementioning

confidence: 99%

Section: Residual Mantle Gravity Anomalies and Residual Topographymentioning

confidence: 99%

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

2018

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“…There is abundant evidence that the lithosphere is highly heterogeneous (Jordan 1975;Afonso et al 2008;Griffin et al 2009;Kaban et al 2016). Variations in temperature and composition at lithospheric depths result in laterally varying shear wave velocity and density anomalies (Khan et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Comparing gravity-based to seismic-derived lithosphere densities: a case study of the British Isles and surrounding areas

et al. 2016

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S U M M A R YLithospheric density structure can be constructed from seismic tomography, gravity modelling, or using both data sets. The different approaches have their own uncertainties and limitations. This study aims to characterize and quantify some of the uncertainties in gravity modelling of lithosphere densities. To evaluate the gravity modelling we compare gravity-based and seismic velocity-based approaches to estimating lithosphere densities. In this study, we use a crustal model together with lithospheric isostasy and gravity field observations to estimate lithosphere densities. To quantify the effect of uncertainty in the crustal model, three models are implemented in this study: CRUST1.0, EuCrust-07 and a high-resolution P-wave velocity model of the British Isles and surrounding areas. Different P-wave velocity-to-density conversions are used to study the uncertainty in these conversion methods. The crustal density models are forward modelled into gravity field quantities using a method that is able to produce spherical harmonic coefficients. Deep mantle signal is assumed to be removed by removing spherical harmonic coefficients of degree 0-10 in the observed gravity field. The uncertainty in the resulting lithosphere densities due to the different crustal models is ±110 kg m −3 , which is the largest uncertainty in gravity modelling. Other sources of uncertainty, such as the V P to density conversion (±10 kg m −3 ), long-wavelength truncation (±5 kg m −3 ), choice of reference model (<±20 kg m −3 ) and Lithosphere Asthenosphere Boundary uncertainty (±30 kg m −3 ), proved to be of lesser importance. The resulting lithosphere density solutions are compared to density models based on a shear wave velocity model. The comparison shows that the gravity-based models have an increased lateral resolution compared to the tomographic solutions. However, the density anomalies of the gravity-based models are three times higher. This is mainly due to the high resolution in the gravity field. To account for this, the gravity-based density models are filtered with a spatial Gaussian filter with 200 km half-width, which results in similar density estimates (±35 kg m −3 ) with the tomographic approach. Lastly, the gravity-based density is used to estimate laterally varying conversion factors, which correlate with major tectonic regions. The independent gravity-based solutions could help in identifying different compositional domains in the lithosphere, when compared to the tomographic solutions.

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Integration of Insights

Dessai

2020

Modern Approaches in Solid Earth Sciences

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3D density model of the upper mantle of Asia based on inversion of gravity and seismic tomography data

Cited by 51 publications

References 100 publications

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

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

Comparing gravity-based to seismic-derived lithosphere densities: a case study of the British Isles and surrounding areas

Integration of Insights

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