Exploration Results at the Wadi Yiba Copper Prospect, Kingdom of Saudi Arabia
Ghazi A. Kattu, Hamad Al Harthi, Zaben M. Al Ghidany, Ibrahim Khalil, Eyad H. Jannadi, Peter R. Johnson, and Alim A. Siddiqui
The Wadi Yiba copper prospect (lat.19o10´N, long. 41o49´E.) is located approximately 580 km south-southeast of Jeddah. In modern times, it was explored by U.S. Geological Survey geoscientists in 1967-1969, who did detailed mapping and sampling, conducted ground electromagnetic (EM), helicopter-borne EM, and magnetometer surveys, completed 10 diamond drill holes totaling 960 m.
Work continued in 1979 by the Riofinex Geological Mission, when numerous east-west sampling traverses were made, and stratigraphic and structural interpretation modeling of the prospect was undertaken.
In 1980, Utah international Inc., a private mining company, conducted further exploration in the area, including geologic mapping, and surface geochemical sampling.
Utah generated a stratigraphic column and completed a structural geology study.
Encouraged by this earlier work, and by the potential for large extensions of the mineralization, the Saudi Geological Survey reassessed this prospect, beginning a program of detailed exploration, which ran from October 2001 to June 2003.
Five geologic profiles were constructed, 85 rock-chip samples were taken, a field-survey grid covering an area of approximately 4 km2 was established, 3 IP east-west profiles about 1.5 km long were made, 6 trenches (totaling 560 m) were dug, and 10 diamond drill holes (totaling 1342 m) were completed.
A detailed structural study of this prospect was also undertaken.
The objective of the ground geophysical study was to define areas of high chargeability and conductivity, of the type generally interpreted as sulfide-rich.
Three east-west IP profiles , each about 1.5 km long, were measured by the SGS geophysics team.
The profiles were located in the southern part of the area, along lines 5000, 5200, and 4800, near drill hole WY 1.
As the measured contrasts were very low, only pseudo cross-sections from the raw data were drawn.
The Wadi Yiba copper prospect is hosted by the Ablah group, which, at the prospect consists of three units.
The base is a clastic unit interpreted by Riofinex to be a deltaic deposit, composed of coarse clastic metasedimentary rocks, including meta-conglomerate, and intruded metadacitic and metaandesitic rocks.
The middle unit is marble with subordinate siltstone and minor mafic volcanic rocks.
The topmost unit is composed of coarse grit and polymict conglomerate.
The rocks were deformed, folded into a tight anticline and faulted, and metamorphosed to the lower greenschist facies.
Deformational structures observed in the prospect area include F1 folds, S1 cleavage, and minor L1 lineations; F2 folds and S2 cleavage; and low- and high-angle north-south- trending faults.
Three main types of mineralization are present:
1- malachite and chalcocite occur within a major north-south-trending fault and associated shear zone in the southeastern part of the prospect area.
2- malachite, chalcocite and traces of bornite and pyrite occur within thin metadacitic sills and vesicular metadacitic to metaandesitic lava flows interbedded with metaclastic sedimentary and metavolcanic sedimentary rocks in the northern part of the prospect area.
3- malachite and chalcocite are locally found in brecciated quartz and quartz-carbonate veins hosted by siliceous dolomite and metadacitic sills and vesicular metadacitic to metaandesitic lava flows.
Diamond drilling intersected thin mineralized zones of copper minerals.
The copper and silver grades are too low and the volumes of mineralized rock too small to be of economic interest. A preliminary resource estimate is 344,736 tonnes at 0.48 percent Cu in the vicinity of drill hole WYA-C008, and 171,456 tonnes at 0.47 percent Cu in the vicinity drill hole WYA-C009.
No further work is recommended.
Kattu, G.A., Al Harthi, H., Al Ghidany, Z.M., Khalil, I., Jannadi, E.H., Johnson, P.R., and Siddiqui, A.A., 2006, Exploration results at the Wadi Yiba copper prospect, Kingdom of Saudi Arabia: Saudi Geological Survey Technical Report SGS-TR-2005-1, 40 p., 25 figs. 10 tables, 5 apps