Contribution to the Geochemical Atlas of the Kingdom of Saudi Arabia: Geochemical Survey of Makkah Al Mukarramah Quadrangle, 21D
Mohammed Al-Thekair, Abdullah H. Al-Johani, Yasir Al-Ghanmi, and Mohammed Al-Nashri
The geochemical survey of Makkah al Mukarramah quadrangle is the first of a series of geochemical surveys that will eventually result in a Geochemical Atlas of the Kingdom.
The survey is based on wadi-sediment samples of grain size -2.00 to +0.177mm collected at a density is one sample per 21 km2 that were analyzed for 10 major and 25 trace elements.
The results are plotted as distribution and geochemical maps for each element.
Means of trace element concentrations in the lithologies of the quadrangle can be classified into three groups relative to their average abundances in the continental earth’s crust: higher, similar and lower.
Means of titanium, iron and silicon in the lithologies of the quadrangle are higher than their means in the continental earth’s crust, while the means of the rest major elements in the lithologies of the quadrangle are lower than their means in the continental earth’s crust.
Statistical interpretation of chemical data revealed the presence of geochemical associations, and the strongest association is found between lanthanum and cerium, and geochemical “rule” is put for expecting element concentration in a wadi-sediment sample from knowing the concentration of the other element.
Anomalous areas are delineated in different parts of the quadrangle, and relationships between mineral compositions and anomalous elements are revealed by XRD study.
Pathfinder elements for gold and silver in the quadrangle are named.
Delineation of anomalous areas is done for follow-up geochemical exploration, and this is one of the aims for the Geochemical Atlas where areas for mineral exploration are identified.
The relationships between geochemistry of lithologies and environmental hazards are shown by drawing maps.
Arsenic is the most harmful in the quadrangle due to its high concentration in agricultural areas and basins for groundwater. Distribution of potassium radioactive isotope, 40K, concentrations is shown on a contouring map for the quadrangle.
Al-Thekair, M., Al-Johani, A.H., Al-Ghanmi, Y., Al-Nashri, M., 2005, Contribution to the Geochemical Atlas of the Kingdom of Saudi Arabia: Geochemical survey of Makkah al Mukarramah quadrangle, 21D, Kingdom of Saudi Arabia: Saudi Geological Survey Technical Report SGS-TR-2004-2, 88 p., 130 figs. 8 tables.