Exploration
Eman M. Kamel; Mohamed S.H. Hammed; Osama E.A. Attia
Abstract
In the recent years, the use of ASTER and Landsat data have become prevalent for mapping different types of rock formations. Specifically, this study utilizes ASTER (L1B) and Landsat 8 (AOL) images to map outcrops of various gypsum facies in Ras Malaab area of west-central Sinai. These gypsum facies ...
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In the recent years, the use of ASTER and Landsat data have become prevalent for mapping different types of rock formations. Specifically, this study utilizes ASTER (L1B) and Landsat 8 (AOL) images to map outcrops of various gypsum facies in Ras Malaab area of west-central Sinai. These gypsum facies are part of a lithostratigraphic group called Ras Malaab, estimated to have been formed during the Miocene period. A range of image processing techniques was employed to create the final facies map including quartz and sulphate indices, composite image band combinations, band ratios, principal component analyses, decorrelation stretching, and SAM mapping followed by supervised classification. By using band combinations, mineral indices, and principal component analyses, sulphate minerals were distinguished from their surroundings. Additionally, decorrelation stretches and band ratios were used to differentiate between primary, secondary, faulted gypsum, anhydrite, and carbonates. The SAM rapid mapping algorithm was also an effective tool to distinguish between the main facies in the studied area and to differentiate between primary massive and bedded gypsum. The results of this study were summarized by creating a facies map of the area using supervised classification, which, in addition to petrographic studies, greatly aided in understanding the distribution of the different gypsum facies.
Kamar Samir; Mohamed El-Sharkawi; Ahmed Niazy El-Barkooky; Mohamed Saleh Hassan Hammed
Abstract
The Precambrian rock assemblages of Umm Tawat area in the North Eastern Desert of Egypt have a distinctive ENE-trending exposure of Hammamat sediments (HS) between the Gebel Gattar granitic pluton and the volcanoclastic succession of Gebel El Dokhan. The present work applies the Landsat-8 data and image ...
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The Precambrian rock assemblages of Umm Tawat area in the North Eastern Desert of Egypt have a distinctive ENE-trending exposure of Hammamat sediments (HS) between the Gebel Gattar granitic pluton and the volcanoclastic succession of Gebel El Dokhan. The present work applies the Landsat-8 data and image processing techniques such as spectral signature, principal component analysis, decorrelation stretch, and band ratios to map the various Precambrian rock units and the lithofacies of the HS and their geological contacts. The recognized mappable units of this assemblage are fully identified by their spectral signature, field verification, lineament analysis, and petrographic description. The resultant high-resolution lithological map based on the maximum likelihood algorithm demonstrates ten fully discriminated mappable units of younger granitoid and HS lithofacies units besides the Dokhan volcanics and metagabro-diorite rock units. The identified five HS lithofacies units are brownish gray conglomerate and sandstone HSf1, a green conglomerate with dominant volcanic fragments HSf2, fine-grained sediments of graywacke and silty-mudstone HSf3, interbedded conglomerates and siltstone with uranium enrichments related to the intrusive contact HSf4, and thermally metamorphosed pelitic sediments HSf5. Remote sensing techniques have been applied for the first time to reveal detailed facies variation of the Hammamat sediments of Umm Tawat. Finally, the results aforementioned above are imported to the Arc GIS database to update the geologic map with precise rock unit boundaries.
