The Salma Caldera complex, northeastern Arabian Shield, Kingdom of Saudi Arabia

K.S. Kellogg

doi:10.3133/ofr85370

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The Salma Caldera complex, northeastern Arabian Shield, Kingdom of Saudi Arabia

K.S. Kellogg

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Abstract

The upper Proterozoic Salma caldera is genetically part of an elongate alkali granitic massif, Jabal Salma. Comenditic ash-flow tuffs, the oldest recognized rocks of the caldera complex, were erupted during caldera collapse associated with the rapid evacuation of the upper, mildly peralkaline part of a zoned magma reservoir. Within the tuff sequence, a massive, lithic-rich intracaldera tuff containing megabreccia blocks is overlain by a layered ash-flow sequence. Later peralkaline granite intruded the caldera ring fracture zone. Metaluminous to peraluminous magma rose beneath the caldera approximately 580 Ma ago and solidified as biotite alkali-feldspar granite, syenogranite, and granophyre. No apparent structural doming of the exposed volcanic rocks along the east side of the caldera took place, and post- emplacement deformation and metamorphism of the caldera are minimal.

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Source-reported bounding extent: 23° to 28° latitude; 38° to 46° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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BibTeX RIS

K.S. Kellogg. 1985. The Salma Caldera complex, northeastern Arabian Shield, Kingdom of Saudi Arabia. https://doi.org/10.3133/ofr85370

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