Geological Study of Arta Geothermal Prospect, Djibouti, GRMF

Abstract

The region of Arta, is located 41km at South-East of the town of the Republic of Djibouti and it is considered as one of geothermal site the most estimated in the country. The project of surface study of Arta's prospect have been developed in collaboration of GRMF funds with the Government of Djibouti, by ODDEG. This study includes the fallowing survey: geological, geophysical ( MTTEM, Gravity, Magnetic),geochemical, sub-surface temperature and social and environmental impact. The purpose of this study, conducted in the Arta sector, is to collect and interpret as much geological formations and structure about the main geometrical features (dipping and faulting), whether magmatic or tectonic in nature. The field survey has been completed in 25 days in surface area of 200 km2 at Arta site and we take sampling of 68 of rock for XRD, thin section and fluid inclusion analysis. We are identified and mapped the emanations which make it possible to envisage the presence of a geothermal field in order to analyze the hydrothermal alterations and the structural geology. The major part of Arta is constituted by acids (rock Rhyolitic) very comparable to those who appear in Ribta and of basalts of Dalha who is the most important unit in the zone of Arta. The northern part of the site has fault lines NNW and those that affect the inner floor of the Gulf. This area superimposed on the extension zone of the stratoide basalts shows a deformation which is expressed by a network of normal east-west mean faults. The central part of the dome structure of the Arta sector in directions N-E and the southern part is faulting in N-S direction. The analysis and interpretation of these data will deduce to understand their origins and their distributions in order to estimate the position of the geothermal reservoir and also the temperature, correlated with all the data development of a conceptual model of the geothermal reservoir of geothermal prospect Arta