Gold resources from clastic Cambrian rocks and their link with underlying Precambrian rocks, southern Sinai, Egypt

• Published in: Arabian journal of geosciences Vol. 13; no. 13
• Main Author: Saber, El Sayed A.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-07-2020; Springer Nature B.V
• Subjects: Anomalies; Basement rock; Cambrian; Climatic conditions; Conglomerates; Continental margins; Depletion; Earth and Environmental Science; Earth science; Earth Sciences; Enrichment; Ferric oxide; Field strength; Geochemistry; Gold; Humid climates; Isotopes; Major elements; Mineralization; Mineralogy; Monazite; Original Paper; Precambrian; Pyrite; Rare earth elements; Ratios; Resources; Rocks; Rubidium; Sandstone; Sediment; Sedimentary rocks; Sediments; Silica; Silicon dioxide; Siltstone; Sulfide; Sulphides; Thorium; Titanium dioxide; Trace elements; Volcanic rocks; Weathering; Xenotime; Yttrium; Zircon; Zirconium; Gold; Geochemical and source rock; Precambrian basement rocks; Cambrian sediments
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-020-05526-0

Geological, mineralogical, and geochemical methods are utilized to discover new gold resources in the Cambrian clastic rocks in the area of southern Sinai. Relation between the Precambrian basement rocks and the overlying gold-bearing Cambrian sediments is also clarified. The Cambrian sediments are underlined by Precambrian basement rocks in which gold mineralization is closely related to intrusive granitic and volcanic rocks. The Cambrian clastic sediments are composed of basal conglomerate and thick sequence of sandstone and siltstone. The mineralogical studies revealed that the conglomerate and quartz-sandstone of the lower Cambrian platform are hosting zircon, monazite, uranophane, thoriante and xenotime, pyrite, and gold. The association of gold, rare earth element (REE)-bearing minerals, and sulfide suggested that these Cambrian sediments are the result weathering of former gold-enriched Precambrian hinterlands. Major and trace elements show the enrichment of silica, high field strength elements (Zr, Y, Nb, Hf, Th, and U), and depletion of all other major elements (Fe
2
O
3
, TiO
2
, MnO, MgO, K
2
O, Na
2
O, and CaO) and large-ion lithophile elements (Rb, Ba, and Sr); among the trace elements, gold shows high concentration range from 0.5 to 13 ppm. REE pattern shows enrichment in LREE and flat HREE with negative Eu anomalies, all of these indicate that the provenance of the present Cambrian sediments is a granitoid-greenstone located to the south. The geochemical parameters (Th/Co, Zr/Co, Th/La, and Th/Yb ratios) and the Paleo-weathering indices (CIA and ICV) for the Cambrian sediments indicate that they were derived from felsic source rocks which were subjected to high chemical weathering under humid climatic condition. The geochemical data and discrimination function plots indicate that the present Cambrian sediments deposited in a passive continental margin.