A comparative study of five volcanic-hosted sulfide mineralizations in the Arabian shield

Abstract EN

Investigation of five volcanogenic base melai sulfide occurrences in the Arabian Shield (Ash Shizm.

Umm Ad Damar, As-Safra, Al , Musayna’ah, and Umm Ash Shalahib) showed that they are located within Hulayfah calc-alkaline volcanic rocks or its equivalents.

The investigations included field, petrographic.

mineralogical and chemical studies.

Felsic, calc-alkaline rock assemblages host these occurrences, with a predominance of rhyolitic rocks and some andesites.

Basalt occurs only in the vicinity of the Ash Shizm mineralization.

These rocks were regionally metamorphosed to low greensehist facies grade.

Deformation and contact metasomatism affected parts of these occurrences producing foliation and local skarn development.

The intensity of mctainorphism and deformation varies between localities.

Later episodes of hydrothermal activity overprinted zones of mineralizations producing serialization, chloritization and silicification.

Geotectonically, these mineral occurrences were formed in different settings.

Ash Shizm bimodal volcanics were probably deposited in an exten-sional regime in a back arc basin.

Umm Ad-Damar, As Safra and AI Musayna’ah calc-alkaline volcanics are interpreted as formed within an island arc environment, while Umm Ash Shalahib volcanics could be considered similar to Andean type deposits related to an active continental margin environment.

Ore microscopic investigations of the mineral assemblages in the five occurrences indicated primary ores that have been coarsened and deformed to variable degrees giving the ores their characteristic brecciated nature reflected in the associated pyrite and other metamorphic texture present.