The timing and compositional evolution of volcanism within northern Harrat Rahat, Kingdom of Saudi Arabia

Stelten, Mark E.; Downs, Drew T.; Champion, Duane E.; Dietterich, H. R.; Calvert, Andrew T.; Sisson, T. W.; Mahood, Gail A.; Zahran, Hani

doi:10.1130/b35337.1

Cited by 14 publications

(20 citation statements)

References 48 publications

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“…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

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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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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“…This stagnation forming melt storage zones is a common geological explanation for many evolved monogenetic volcanic fields on different tectonic settings on Earth (e.g. [8,11,13,14,43,52]). Thus, magmas coming to the planet surface directly from the asthenosphere tend to be mafic, while those coming from crustal melt storages tend to be either intermediate or felsic (Figure 5).…”

Section: Magmatic Plumbing Systemsmentioning

confidence: 99%

“…In the west part of the Arabian shield [42,52,65], where mostly lava flows as effusive monogenetic emissions have occurred through time [66,67], recent investigations have proposed a plumbing system composed of a melting region in the asthenosphere with magma stagnation zones in the upper part of the lower crust (e.g. [14]). Similarly, in the Colombian Andes, recently identified intermediate to acidic effusive monogenetic volcanoes forming volcanic fields have been linked to a plumbing system that include a magmatic reservoir located in the upper part of the lower crust [12].…”

Section: Examplesmentioning

confidence: 99%

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Effusive Monogenetic Volcanism

Murcia¹,

Németh²

2021

Updates in Volcanology - Transdisciplinary Nature of Volcano Science

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The study of monogenetic volcanism around Earth is rapidly growing due to the increasing recognition of monogenetic volcanic edifices in different tectonic settings. Far from the idea that this type of volcanism is both typically mafic and characteristic from intraplate environments, it occurs in a wide spectrum of composition and geological settings. This volcanism is widely known by the distinctive pyroclastic cones that represent both magmatic and phreatomagmatic explosive activity; they are known as scoria or spatter cones, tuff cones, tuff rings, maars and maar-diatremes. These cones are commonly associated with lava domes and usually accompanied by lava flows as part of their effusive eruptive phases. In spite of this, isolated effusive monogenetic emissions also appear around Earth’s surface. However, these isolated emissions are not habitually considered within the classification scheme of monogenetic volcanoes. Along with this, many of these effusive volcanoes also contrast with the belief that this volcanism is indicative of rapidly magma ascent from the asthenosphere, as many of the products are strongly evolved reflecting differentiation linked to stagnation during ascent. This has led to the understanding that the asthenosphere is not always the place that directly gives rise to the magma batches and rather, they detach from a crustal melt storage. This chapter introduces four singular effusive monogenetic volcanoes as part of the volcanic geoforms, highlights the fact that monogenetic volcanic fields can also be associated with crustal reservoirs, and outlines the processes that should occur to differentiate the magma before it is released as intermediate and acidic in composition. This chapter also provides an overview of this particular volcanism worldwide and contributes to the monogenetic comprehension for future studies.

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“…A method that has proved useful for providing ages on young flows in arid environments that lack extensive vegetation cover and erosion is the 36 Cl cosmogenic surface-exposure dating (e.g., Vazquez and Woolford, 2015;Downs et al, 2018;Downs et al, 2019;Stelten et al, 2018;Stelten et al, 2020;Bromley et al, 2019). We utilized the 36 Cl cosmogenic method (see Supplementary Material for details on sample collection and analysis) for the Brushy Butte flow field to determine its emplacement age, and we couple this with 40 Ar/ 39 Ar ages of surrounding older tholeiitic basalts to better understand the eruptive history of volcanism prior to eruption of the Brushy Butte flow field.…”

Section: Geochronologymentioning

confidence: 99%

A Multidisciplinary Investigation Into the Eruptive Style, Processes, and Duration of a Cascades Back-Arc Tholeiitic Basalt: A Case Study of the Brushy Butte Flow Field, Northern California, United States

et al. 2021

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The Cascades back-arc in northern California is dominated by monogenetic tholeiitic basalts that erupted throughout the Pleistocene. Elucidating their eruptive history and processes is important for understanding potential future eruptions here. We focus on the well-exposed monogenetic volcano that emplaced the Brushy Butte flow field, which constructed a ∼150 m tall edifice, has flow lobes up to >10 km long, and in total covers ∼150 km2 with an eruptive volume of 3.5 km3. We use a multidisciplinary approach of field mapping, petrography, geochemistry, paleomagnetism, geochronology, and lidar imagery to unravel the eruptive history and processes that emplaced this flow field. Tholeiitic basalts in northern California have diverse surface morphology and vegetation cover but similar petrographic appearances, which makes them hard to distinguish in the field. Geochemistry and paleomagnetism offer an independent means of distinguishing tholeiitic basalts. Brushy Butte flow field lavas are similar in major-oxide and trace-element abundances but differ from adjacent tholeiitic basalts. This is also apparent in remanent magnetic directions. Additionally, paleomagnetism indicates that the flow field was emplaced during a geologically brief time interval (10–20 years), which 36Cl cosmogenic dating puts at 35.7 ± 1.7 ka. Lidar imagery shows that these flows erupted from at least 28 vents encompassing multiple scoria cones, spatter cones, and craters. Flows can be grouped into four pulses using stratigraphic position and volume. Pulse 1 is the most voluminous, comprising eight eruptions and ∼2.3 km3. Each subsequent pulse started rapidly but decayed quickly, and each successive pulse erupted less lava (i.e., 2.3 km3 for pulse 1, 0.6 km3 for pulse 2, 0.3 km3 for pulse 3, and 0.2 km3 for pulse 4). Many of these flows host well-established lava channels and levees (with channel breakouts) that lead to lava fans, with some flows hosting lava ponds. Similar flow features from tholeiitic eruptions elsewhere demonstrate that these morphologies generally occur over weeks, months, or longer (e.g., Puʻu ʻŌʻō eruption at K–llauea, Hawaiʻi). This multidisciplinary study shows the range of eruptive styles and durations of a Cascades back-arc eruption and illustrates how potential future tholeiitic eruptive activity in the western United States might progress.

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The timing and compositional evolution of volcanism within northern Harrat Rahat, Kingdom of Saudi Arabia

Cited by 14 publications

References 48 publications

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

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

Effusive Monogenetic Volcanism

A Multidisciplinary Investigation Into the Eruptive Style, Processes, and Duration of a Cascades Back-Arc Tholeiitic Basalt: A Case Study of the Brushy Butte Flow Field, Northern California, United States

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