عنوان

Geology of the Early Paleogene phosphorite deposits of northwestern Saudi Arabia

TLpq304334835

انگلیسی

Geology of the Early Paleogene phosphorite deposits of northwestern Saudi Arabia

[Thesis]

W. S. A. Matter

King Fahd University of Petroleum and Minerals (Saudi Arabia)

1996

399

M.S.

King Fahd University of Petroleum and Minerals (Saudi Arabia)

1996

Economic phosphorite deposits were discovered in the Early-Paleogene succession of northwestern Saudi Arabia in 1965. The stratigraphy, micropaleontology and microfacies analyses of the succession have already been carried out, but no attempt has yet been made to study the mineralogical composition of the ore, its trace elements and geochemical characteristics in any detail, or to discuss its origin or provide a practical means for classifying its various grades. The ore is mainly composed of microcrystalline apatite (with an average of 46.35%), dolomite (with an average of 36.69%) and calcite (averaging 13.14%) and abundant trace elements, such as uranium (up to 300 pp.) and vanadium (up to 3000 ppm). Other than its rich phosporous content, such relatively high values of trace elements can warrant the exploitation of the ore which can alone justify its economic exploitation. A practical classification for the phosphorite deposits in both binary and ternary diagrams was attempted, with three cut points at 18%, 8% and 1% usd\rm P\sb2O\sb5usd, separating phosporites from phosphoritic and slightly phosphoritic rocks, respectively. Values below 1% usd\rm P\sb2O\sb5usd were ignored. The detailed mineralogical, petrographical and geochemical analyses of the ore as well as its stratigraphical relationships suggest a biochemical origin, in a partially restricted continental shelf. Such partial restriction was mainly provided by a large number of swells and basins that were apparently active prior to the deposition of the phosphorite sequence, and hence provided the necessary configuration of the sea-bottom for the deposition of the ore.

Earth sciences

Geology

W. S. A. Matter

p

[Thesis]

276903

a

Y