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

Open-File Report 85-370

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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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Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
The Salma Caldera complex, northeastern Arabian Shield, Kingdom of Saudi Arabia
Series title:
Open-File Report
Series number:
85-370
Year Published:
1985
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Description:
i, 23 p. :ill., maps ;28 cm.
Country:
Saudi Arabia
Online Only (Y/N):
N
Additional Online Files (Y/N):
N