Saudi Geological Survey

Modern base metal exploration in the kingdom of Saudi Arabia (KSA) has been in effect for less than a half-century and much of the acquired information is not publicly available. Consequently, information about the geology of known deposits and the potential for future discoveries is difficult to obtain outside the country, This presentation aims to present a concise and systematic overview of the geology of base metal mineralization in Saudi Arabia to raise the awareness of the international mineral industry of the opportunities for base metal exploration in (KSA).

Basic geologic and geographic data on more than 200 base metal occurrences were collected in spreadsheet appendices and displayed in distribution maps. Grade-tonnage data, also presented in spreadsheet format, are available for 37 base metal deposits. In addition, 23 deposits were selected for summary descriptions accompanied by geologic maps, sections, and photographs.

Saudi Arabia base metal deposits are found in three tectonic settings: (1) The Arabian shield comprising largely volcanic and sedimentary rocks of Neoproterozoic age; (2) Tertiary cover rocks of the Red Sea coastal plain; and (3) Quaternary sediments in the axial fracture zone of the Red Sea deeps.

The Arabian shield was created by the accretion of tectonostratigraphic terranes during convergence of East and West Gondwana and took place along sutures represented by faults between the terranes. Eight tectonostatigraphic terranes have been defined in the Arabian shield; four in the western half of the shield formed in a juvenile oceanic environment (i.e. ensimatic) whereas those in the eastern portion were derived from mixed oceanic and evolved continental sources.

Sedimentary processes and deposits on the Red Sea coastal plain were significantly controlled by tectonics accompanying opening of the Red Sea itself. Subsidence and marina transgression took place mainly between the end of the Oligocene and the end of the Early Miocene.

The Rad Sea axial-fracture zone, which resulted from seafloor spreading during the early to middle Pliocene, comprises a series of troughs floored by tholeiitic basalt and, in many cases, partially filled with biogenic pelagic carbonate, eolian detritus, and brine pools.

Base metal deposits in the Arabian Shield are predominantly Cu-Zn volcanogenic massive sulfides (VMS). Although several share the typical morphological characteristics of VMS deposits (i.e. , a discordant alteration / stringer zone capped by a dome-shaped massive sulfide lens or lenses), other deposits are best described as wispy, sheet-like bodies roughly conformable with enclosing strata (usually volcaniclastic rocks). These deposits lack both a massive sulfide dome and an underlying discordant feeder zone. All VMS deposits are found in the ensimatic tectonostratigraphic terranes of the western half of the shield. Other base metal deposits in the Arabian shield comprise discordant, epithermal, Au-rich veins or stockworks, carbonate replacement in predominantly volcanic settings, shear zone replacements, and a possible porphyry-cu. Many more deposits remain unclassified due to insufficient descriptions in the available literature.

Deposits in the Red Sea coastal plain region consist of high-grade accumulations of Mn-rich secondary Zn-Pb minerals in Miocene carbonates and probably represent deeply weathered Mississippi Valley-type (MVT) deposits. Sulfide-rich Cu-Zn sediments in the Atlantis II deep of the Red Sea