干旱区生态环境知识资源中心

Chemostratigraphic and petrographic investigations integrated with remote sensing lithologic mapping are used in harmony to discriminate and delineate the outcropping sedimentary successions at Ras Banas Peninsula, Red Sea coast. Tectonically, Ras Banas peninsula is considered as a part of Pre-Miocene continental slope. Their sedimentary successions account the sedimentation history from Middle Miocene up to Holocene which in part documents the deformational impacts that accompanied the Red Sea rifling. The Ras Banas sedimentary succession exhibits frequent unconformities and conspicuous lithologic variations comprising mixed siliciclastics/carbonate facies, evaporites, open marine and organic build up limestone as well as coral reefs, continental sandy gravels and beach sands. The carbonate succession at the area documents the highstand status of the Red Sea water from Middle Miocene to Pleistocene in accord to the global sea-level fluctuations. The chemical data of the studied rock units substantiates the field and petrographical results. On silica- lime- magnesia diagram, the syn-rifting mixed siliciclastics/carbonates are scattered between the quartz and dolomite reference points. The post-rifting carbonates are mainly pure dolostone, limestone and sandy limestone. Norm calculations indicate that the evaporites are mainly gypsum and anhydrite with substantial normative dolomite. The tectono-sedimentary evolution of Ras Banas sedimentary sequence in relation to Red Sea rifling phases and sea level fluctuations is discussed. New mapping was undertaken for the Ras Banas Peninsula using remote sensing and GIS techniques including band ratioing, principle component analysis and false color composition. Based on mineralogical data, special interest has been paid to the diagnostic spectral features that discriminate between evaporites and carbonates on one hand and between dolomite and calcite on the other.