GEOLOGY OF COASTAL AREA OF WADI MAWR RED SEA, REPUPLIC OF YEMEN

Abstract

One of the main aim of the present work is to study the sedimentological characteristics of the Quaternary coastal sediments (soil) of one of the major Tihama wadi in the Red Sea of Yemen; called Wadi Mawr. The main other aim is land use evaluation of the study area based on: 1) the geomorphological and geological factors that affecting the coastal sediment,, 2) the environmental site characteristics, 3) the impacts of natural and socio-economic hazards. To achieve these goals different laboratory analyses e.g. grain size heavy minerals, petrographic, X-ray diffraction and chemical analyses, were carried out in addition to the field investigation including the samples. One hundred and thirty six samples were collected from ninety three selected sites representing the different geomorphological units allover the study area.

The study area was divided into sixteen geomorphological units. These units which include the mountainous and coastal regions are namely from east to west: foothills, alluvial fans, plateaus, wadi plain, terraces, wadi channels, delta, evaporite hills, sabkhas, coastal dunes, beach, mangrove, lagoons, spit, bars and coral reef The last eight units are located within the tidal area around the Al-Luhayyah district. Each unit is characterized by certain geomorphological and geological features. It seems that these units represent direct reflection of the integrating action of the tectonic, structures, lithology and sedimentary processes. These features ofthe units are summarized as follows: The distribution of heavy mineral and light minerals of the study sand fractions is mainly factors of which are 1) Petrographic nature of source rocks 2) Weathering of the parent rocks. 3) Differential mechanical destruction during transportation. 4) Hydraulic processes discussed by means of grain size, shape and density. 5) Chemical decomposition of the heavy minerals. This distribution shows that the study area is receiving sediments derived at least from two important provenances. The first one is dominated by granitic rocks and dolerites that contain abundance in green hornblende, biotite, epidote and monazite. The second provenance is dominated by metamorphic