Geophysical investigations in the Mahd adh Dhahab district, Kingdom of Saudi Arabia, with a section on shallow seismic refraction profiles

Abstract

Extensive geophysical investigations have been carried out at the Mahd adh Dhahab gold mine, Kingdom of Saudi Arabia, by the U.S. Geological Survey Saudi Arabian Mission as part of a multidisciplinary study of the district.The three major objectives of the study were: 1) to define unexposed areas of probable sulfide mineralization for further exploration; 2) to infer the geologic relations beneath the covered areas surrounding Jabal Mahd adh Dhahab; and 3) to provide further constraints on structural and genetic models of the geologic history.The study area measures 1.5 km in a north-south direction by 2.9 km in an east-west direction and is centered approximately on the mine workings. Work was completed during the period between mid-1973

Geology and hydrothermal alteration at the Madh adh Dhahab epithermal precious-metal deposit, Kingdom of Saudi Arabia

“…These zones correspond very closely to zones of anomalous concentrations of potassium-40 delineated by radiometric surveys (Gettings, 1981).…”

Paleomagnetic investigations at Mahd adh Dhahab, Kingdom of Saudi Arabia

“…) 1982) , Stacey and others (1980) , and Calvez and . Geophysical investigations are described in Davis and others (1965), Arabian Geophysical and Surveying Company (ARGAS) (1975), Flanagan and Pitkin (197^), and Gettings (1981).…”

“…A suite of oriented bedrock specimens were collected from the Jabal Mahd adh Dhahab area, Kingdom of Saudi Arabia, during the course of geophysical investigations of the base and precious metal deposits in the district. The primary purpose of this part of the work was to define the natural remanent and induced rock magnetizations of the various lithologies of the district, to be used in the interpretation of a detailed magnetic map of the area (Gettings, 1981). The results of the natural remanent magnetization (NRM) measurements were so interesting as to merit consideration of paleomagnetism in the samples collected; however, the sampling program was not designed for a paleomagnetic study, and the data examined is not optimum for paleomagnetic and structural analyses.…”

“…The Mahd adh Dhahab area is located a few km southwest of a major northwesttrending system of Najd faults, and is bounded to the east by a northeast-trending right lateral fault that lies beneath the alluvium (Goldsmith and Kouther, 1971;Worl, 1978b;Kemp and others, 1982). Mahd adh Dhahab itself is located on the axis of a large northeast-plunging antiform (Kemp and others, 1982) that is well defined by the aeromagnetic data of the area (Gettings, 1981). At least two periods of folding deformation are recognised Luce and others (1975) and Worl (1978b).…”

“…The presence of lapilli and bombs of various sizes indicate that the rocks are at least in part from a near-vent facies. Considerable potassium and iron alteration occurs, hydrothermal in origin (Worl, 1978a;Hakim, 1980;Gettings, 1981). However, regionally these rocks are little altered and have only been slightly metamorphosed in the low greenschist facies (Kemp and others, 1982).…”