Abstract
Geographic information system and remote sensing techniques are used to determine the spatial association between the hydrogeochemical and seismological evidences of well-known geothermal fields in South Sinai. Manipulation, combination, overlay, integration and reattribution GIS functions have been used to explore the possible new occurrences of geothermal resources in South Sinai. Moreover, surface observations and lineament analysis of satellite images are used to delineate the active geothermal areas. The distribution of recent earthquake epicentres over South Sinai shows three main active trends (N 6A degrees E, N 40A degrees-75A degrees E and N 50A degrees-60A degrees W) conformable with the long fault extensions extracted from ETM+7 and ASTER GDEM satellite images and comprise the well-known hot springs in South Sinai. It is found that wherever the N 6A degrees E trend intersects both of N 50A degrees-60A degrees W or N 40A degrees-75A degrees E, the temperature of spring waters is remarkably increased. This feature could be attributed to the deep penetration of groundwater along the N 6A degrees E fault trend (Gulf of Aqaba trend). The seismicity patterns of well-known and newly predicted geothermal sites show that the majority of earthquakes have focal depth range between 3 and 33 km (within the upper Earth crust) and have micro to moderate magnitude (0.5 a parts per thousand yenaEuro parts per thousand Mb a parts per thousand currency signaEuro parts per thousand 4.5). In addition, the maximum focal depth of events reached up to 50 km at the Hammam Faroun area revealing the deep-seated thermal source. The main chemical type of the known thermal water of South Sinai is Cl-Na, indicating a long flow pathway of this water. The high calcium contents of thermal water of South Sinai are accompanied with remarkably low sulphates. This could be attributed to the microbial or thermal reduction of sulphates in contact with organic carbon which is confirmed by the emission of H2S gas observed at the known thermal field sites. As a result, thermal waters of the Hammam Faroun and Hammam Musa are undersaturated with respect to gypsum and anhydrite. The hydrochemistry of the newly predicted thermal sites exhibit similar pattern of the known thermal waters. Such observations are used as indicators to locate six predicted new occurrences of geothermal fields in South Sinai.