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

Geosphere
By: , , , , , , , and 
https://doi.org/10.1130/GES01625.1

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Abstract

We present a detailed geologic investigation of Pleistocene to Holocene mafic volcanism within the northernmost part of the Harrat Rahat volcanic field, proximal to the city of Al-Madinah, Saudi Arabia. Our study area covers ∼570 km2, and encompasses lava flows, scoria cones, and shield volcanoes of 32 mapped eruptive units consisting of continental, intraplate alkalic and tholeiitic basalts, hawaiites, and a mugearite that erupted from at least 1014 ± 14 ka to a single Holocene event at 1256 A.D. Typical lava flows are roughly 10–15 km long, although they reach nearly 23 km, 1–3 km wide, and ∼10 m thick. The majority of eruptives in our study area erupted ca. 400–340 ka and ca. 180–100 ka. Despite small individual volumes (<1 km3 dense rock equivalent), each unit resulted from eruption of a distinct magma batch that was influenced by clinopyroxene, olivine, and plagioclase fractionation. Some of these units are interpreted to have undergone magma mixing prior to eruption. Combining our age determinations, geochemistry, and paleomagnetic data sets indicates that several eruptions were temporally and/or spatially clustered. Aligned scoria cones and elongate vent edifices were constructed atop fissure vent systems that reflect the stress field controlling dike ascent through the middle to upper crust.

Publication type Article
Publication Subtype Journal Article
Title Volcanic history of the northernmost part of the Harrat Rahat volcanic field, Saudi Arabia
Series title Geosphere
DOI 10.1130/GES01625.1
Volume 14
Issue 3
Year Published 2018
Language English
Publisher Geological Society of America
Contributing office(s) Volcano Science Center
Description 30 p.
First page 1253
Last page 1282
Country Saudi Arabia
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