Comprehensive Mapping of the Island Arc Rocks in the Marahiq Area, South Eastern Desert, Egypt

Abstract

Remote sensing and geochemical data are used to discriminate between the different varieties of island arc assemblage covering Marahiq area, South Eastern Desert of Egypt. The Precambrian basement rocks exposed in the study area comprise ophiolite and island arc assemblages. The ophiolitic rocks include serpentinites and talc-carbonate, while the metavolcanics and metavolcanosedimentary rocks represent the island arc assemblage. Petrographically, the island arc units are differentiated in to metabasalt, meta-andesite, metadacite, meta-andesitic tuffs, chlorite talc schist and biotite chlorite schist. The geochemical data revealed that these metavolcanics and metavolcanosedimentary rocks are calcalkaline to tholeiite in nature with low to medium-K, and likely represent an immature island arc. Image processing techniques applicable to the Enhanced Thematic Mapper (ETM+) data are used for mapping and delineating exposures of the different island arc units at the Marahiq area. Principal component analysis, minimum noise fraction and band rationing techniques provide efficient data for lithological mapping. New detailed map was generated as a result of the processed ETM+ images.

Trace elements and isotope data of the Um Garayat gold deposit, Wadi Allaqi district, Egypt

“…Thrust faulting extending NW-SE delineates the contact between the ophiolites and island arc rocks. Geochemical data of the metavolcanic rocks reveal their low to medium-K, calc-alkaline to tholeiite nature, suggesting an immature island arc setting (Emam et al 2014). El Nisr (1997) suggested a transitional environment between continental arc and continental margin for the intermediate members of these metavolcanics.…”