Mahd Adh Dhahab: Precambrian epithermal gold deposit, Kingdom of Saudi Arabia

Open-File Report 79-1190
By: , and 

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Abstract

The largest and most productive mine in Saudi Arabia in ancient and modern times has been Mand adh Dhahab. Country rocks in the district are pyroclastic and clastic rocks that belong to the Halaban group of late Precambrian age. From oldest to youngest, the units are: andesite, lower agglomerate, lower tuff, upper agglomerate, and upper tuff. These units have been tilted northerly forming a homocline and are complexly broken by six sets of faults; three of these sets, which strike N.25°-30°W., N.10°W. to N.20°E., and N.30°-60°E. contain productive quartz veins.

The principal ore minerals are native gold and silver, pyrite, chalcopyrite, sphalerite, and galena, plus minor tetrahedrite and argentite. The gold and silver are finely disseminated in the veins and in the altered selvages of the veins. Widespread potassic and propylitic alteration accompanied ore formation.

Early widespread propylitic and potassic alteration and sulfide and quartz precipitation are believed to have taken place at temperatures below 350°C, based on K-feldspar stability and sulfur isotope data . Most of the quartz and precious metals precipitated in the range 200°-150°C, based on studies of fluid inclusions. The isotopic data indicate that sulfur and carbon came from a deep-seated source, but that the water, especially in the later stages, was meteoric. 

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Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Mahd Adh Dhahab: Precambrian epithermal gold deposit, Kingdom of Saudi Arabia
Series title Open-File Report
Series number 79-1190
DOI 10.3133/ofr791190
Year Published 1979
Language English
Publisher U.S. Geological Survey
Description ii, 33 p.
Country Saudi Arabia
Other Geospatial Mand adh Dhahab
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