Volcanic history of the northernmost part of the Harrat Rahat volcanic field, Saudi Arabia

Downs, Drew T.; Stelten, Mark E.; Champion, Duane E.; Dietterich, H. R.; Nawab, Zohair A.; Zahran, Hani; Hassan, K. H.; Shawali, Jamal

doi:10.1130/ges01625.1

Cited by 47 publications

(23 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Park et al, 2007Park et al, , 2008Hansen et al, 2007Hansen et al, , 2008Hansen et al, , 2012Tang et al, 2016Tang et al, , 2018Tang et al, , 2019Kaviani et al 2018). Petrological studies of Cenozoic rocks in the Arabian Shield (Duncan et al, 2016;Downs et al, 2018) also support the hypothesis of a northward mantle flow. This possible northward flow of the upwelled material affects not only the upper mantle but also the crustal structure beneath the Red Sea and Arabian Shield.…”

Section: Widespread Regional Mantle Flow Beneath Afar Red Sea W Armentioning

confidence: 61%

Crustal and uppermost mantle shear wave velocity structure beneath the Middle East from surface wave tomography

Kaviani

Ambert

Moradi

et al. 2020

Geophysical Journal International

View full text Add to dashboard Cite

SUMMARY We have constructed a 3-D shear wave velocity (Vs) model for the crust and uppermost mantle beneath the Middle East using Rayleigh wave records obtained from ambient-noise cross-correlations and regional earthquakes. We combined one decade of data collected from 852 permanent and temporary broad-band stations in the region to calculate group-velocity dispersion curves. A compilation of >54 000 ray paths provides reliable group-velocity measurements for periods between 2 and 150 s. Path-averaged group velocities calculated at different periods were inverted for 2-D group-velocity maps. To overcome the problem of heterogeneous ray coverage, we used an adaptive grid parametrization for the group-velocity tomographic inversion. We then sample the period-dependent group-velocity field at each cell of a predefined grid to generate 1-D group-velocity dispersion curves, which are subsequently inverted for 1-D Vs models beneath each cell and combined to approximate the 3-D Vs structure of the area. The Vs model shows low velocities at shallow depths (5–10 km) beneath the Mesopotamian foredeep, South Caspian Basin, eastern Mediterranean and the Black Sea, in coincidence with deep sedimentary basins. Shallow high-velocity anomalies are observed in regions such as the Arabian Shield, Anatolian Plateau and Central Iran, which are dominated by widespread magmatic exposures. In the 10–20 km depth range, we find evidence for a band of high velocities (>4.0 km s–1) along the southern Red Sea and Arabian Shield, indicating the presence of upper mantle rocks. Our 3-D velocity model exhibits high velocities in the depth range of 30–50 km beneath western Arabia, eastern Mediterranean, Central Iranian Block, South Caspian Basin and the Black Sea, possibly indicating a relatively thin crust. In contrast, the Zagros mountain range, the Sanandaj-Sirjan metamorphic zone in western central Iran, the easternmost Anatolian plateau and Lesser Caucasus are characterized by low velocities at these depths. Some of these anomalies may be related to thick crustal roots that support the high topography of these regions. In the upper mantle depth range, high-velocity anomalies are obtained beneath the Arabian Platform, southern Zagros, Persian Gulf and the eastern Mediterranean, in contrast to low velocities beneath the Red Sea, Arabian Shield, Afar depression, eastern Turkey and Lut Block in eastern Iran. Our Vs model may be used as a new reference crustal model for the Middle East in a broad range of future studies.

show abstract

Section: Widespread Regional Mantle Flow Beneath Afar Red Sea W Armentioning

confidence: 61%

Crustal and uppermost mantle shear wave velocity structure beneath the Middle East from surface wave tomography

Kaviani

Ambert

Moradi

et al. 2020

Geophysical Journal International

View full text Add to dashboard Cite

show abstract

“…Tang et al () identified no high temperature in the upper‐mantle lid below the volcanic regions, indicating adiabatic ascent of magmas. Also, rapid ascent and eruption of magma is suggested by geochemical analyses (e.g., Downs et al, ; Duncan et al, ), indicating little interaction between hot magmas and the crust. Therefore, the involvement of a thermal anomaly in the triggering of the observed crustal S velocity decreases must be minimal.…”

Section: Discussionmentioning

confidence: 99%

“…Interestingly, age compilations of Cenozoic volcanic rocks with tectonic events manifests a northward propagation of the volcanism (Krienitz et al, ). Also, the spread of volcanic centers within northern Harrat Rahat demonstrates the distribution of the older basaltic vents in the south to younger northward (Downs et al, ). These evidences appear to support the model of lateral mantle flow.…”

Section: Discussionmentioning

confidence: 99%

Shear Velocity Structure Beneath Saudi Arabia From the Joint Inversion of P and S Wave Receiver Functions, and Rayleigh Wave Group Velocity Dispersion Data

et al. 2019

Self Cite

View full text Add to dashboard Cite

We develop a new 3-D shear velocity model for the lithosphere and sublithospheric mantle under Saudi Arabia by jointly inverting P wave receiver functions, S wave receiver functions, and fundamental-mode Rayleigh wave group velocities. P and S receiver functions are calculated from earthquakes recorded between 2012 and 2015 at 156 Saudi National Seismic Network stations operated by the Saudi Geological Survey. Rayleigh wave dispersion data are extracted from independent tomographic studies. Our model reveals significant lateral variations in crustal and upper-mantle S velocity below Saudi Arabia. Particularly, a low-velocity zone, with minimum S velocity of~4.0 km/s in the depth range of 70-190 km, is observed under the Arabian Shield coinciding with Cenozoic surface volcanism. The low-velocity zone is found consistent with the presence of partial melts in the mantle and interpreted as a potential deep magma source for the volcanism in western Arabia. We propose that magmas responsible for the Arabian volcanism may be derived from multiple sources. Both lithospheric thinning and the Afar plume trigger magma production beneath southwestern Arabia, while decompression melting caused by the lithospheric thinning may be the main factor in the central and northern portions. Furthermore, we find evidence for localized crustal low shear velocity anomalies (2-4% reductions) that appear spatially correlated to the volcanism; these may be due to fractures caused by magma ascent and small amounts of partial melt in the crust. This spatial distribution of S velocity reductions may indicate the plumbing system for magma ascent underneath western Arabia.

show abstract

“…The northern part of HR is marked by a linear vent axis trending N30°W (Figure a), subparallel to trends in the Neoproterozoic basement. 40 Ar/ 39 Ar age dates for lavas from northern HR are all younger than 1.2 Ma, with the majority of flows younger than 400 ka yet with only one confirmed Holocene eruption (Downs et al, ). Eruptions recurrence rates are estimated to be 2.5–3.2 ka (Stelten et al, ).…”

Section: Introductionmentioning

confidence: 99%

Crustal Magmatism and Anisotropy Beneath the Arabian Shield—A Cautionary Tale

et al. 2019

View full text Add to dashboard Cite

Volcanism in Saudi Arabia includes a historic eruption close to the holy city of Al Madinah. As part of a volcanic hazard assessment of this area, magnetotelluric (MT) data were collected to investigate the structural setting, the distribution of melt within the crust, and the mantle source of volcanism. Interpretation of a new 3-D resistivity model includes a shallow graben beneath thin lava fields (Harrats), a melt-free upper crust, and decompression melting in the asthenosphere below thin lithosphere. Within the lower crust the model images elongate conductivity anomalies, one of which was attributed in a previous MT study to melt. The regional MT data, combined with perspective from geology and geophysical modeling, suggest the lower crust is anisotropic with no interconnected melt zones. These divergent interpretations have distinct hazard implications and highlight the importance of large survey aperture and anisotropic modeling to MT studies of volcanic regions. Lower-crustal anisotropy extends beyond the Harrat, with the most conductive direction oriented N10°E and a factor of 3-5, determined from 2-D anisotropic inversion, between the most and least conductive directions. The enhanced conductivity is likely due to interconnected grain boundary graphite, while the anisotropy direction reflects either frozen-in fabric from Neoproterozoic stabilization of the Arabian Shield or modern ductile deformation driven by channelized asthenospheric flow coupled through a thin rigid mantle lid. Asthenospheric melt is interpreted to transect the crust primarily through diking, with limited melt storage and short residence times in the crust.Plain Language Summary Volcanism within the lava fields, or Harrats, of Saudi Arabia includes historic eruptions, such as an eruption in 1256 CE near the holy city of Al Madinah. As part of a volcanic hazard assessment of northern Harrat Rahat, geophysical studies produced a three-dimensional model of electrical resistivity of the crust and upper mantle. In contrast to a more local study, the model shows no evidence of magma in the crust. This is consistent with other evidence in the region that suggests magma does not stay in the crust for long times but ascends rapidly from the upper mantle to the surface. This finding provides a snapshot in the lifecycle of this volcanic field and is important to understanding the hazards it poses. Our model also finds deep electrical anisotropy, probably due to a preferred direction or "fabric" in the lower crust. This fabric may be ancient, frozen in millions of years ago when the crust formed. Alternately, it may be caused by ongoing flow in the ductile lower crust in response to deeper mantle flow.

show abstract

Volcanic history of the northernmost part of the Harrat Rahat volcanic field, Saudi Arabia

Cited by 47 publications

References 76 publications

Crustal and uppermost mantle shear wave velocity structure beneath the Middle East from surface wave tomography

Crustal and uppermost mantle shear wave velocity structure beneath the Middle East from surface wave tomography

Shear Velocity Structure Beneath Saudi Arabia From the Joint Inversion of P and S Wave Receiver Functions, and Rayleigh Wave Group Velocity Dispersion Data

Crustal Magmatism and Anisotropy Beneath the Arabian Shield—A Cautionary Tale

Contact Info

Product

Resources

About