"HYDROGEOLOGICAL STUDY ON EL-BRUCK AREA AND ITS ADJACENT AREAS, NORTH CENTRAL SINAI, EGYPT”

Abstract

This Thesis focuses on the study of the geology, hydrogeology and hydrochemistry of the pre-Quaternary aquifer in El-Bruk area, north central Sinai. A total of 81 samples were collected from Gebel El-Bruk succession ranging in age from the Early Cretaceous to Early Eocene. In addition a total of 133 subsurface ditch samples were taken from El-Bruk well no. 16 covering an intervalfrom Late Jurassic to Late Cretaceous. Determination of age is based on both a lithological correlation and paleontological studies ( calcareous nannofossils, palynomorphs and diatoms). Granulometric analysis of the subsurface sandstones has shown that the sediments were deposited in a flwviatile condition in high energy active environments. Most of the sediments were transported as graded bedload while the rest represents a mixture of rolled grains and suspension sediments in variable proportions. Mineralogical examination has shown that the essential carbonate minerals are calcite and dolomite; siderite is a minor constituent. Other non• carbonate minerals include quartz, feldspar, hematite and gypsum. The clay minerals comprise kaolinite and mixed-layer varieties. Petrographic examination of the studied rocks has led to the recognition of a number of sandstone and carbonate facies and several depositional environments were suggested including fluvial (Malha Formation), supratidal to intertidal (Halal Formation), inner neritic (Matulla-Wata Formations), shallow to deep-marine (Sudr Formation), deep-marine (Esna Formation) and shallow warm-water marine environments (Thebes Formation). Two main diagenetic stages affecting sandstones were suggested: an early stage that took place from deposition to shallow burial realm, and a late stage that affecting sediments at deeper levels, during and after uplift. On the other hand, carbonate diagenesis includes several processes such as dolomitiation, dissolution, cementation, neomorphism and compaction. Ground water in the study area is available mainly in Upper Cretaceous limestone and Lower Cretaceous sandstone aquifers. These aquifer are considered as a confined aquifer. The direction of ground water flow is from southeast to northeast and north in Upper Cretaceous aquifer and from south to north in Lower Cretaceous aquifer.