World Geothermal Congress 2020+1
March - October, 2021

Field Geology of Ambado-PK 20


[ODDEG, Djibouti]

The geology of the Republic of Djibouti is marked by the triple joint between 3 different plates that created the Afar depression. The convergence which created rifts are those of the Red Sea, the Gulf of Aden and the East African rift. The rock formation of Djibouti is mainly characterized by Miocene, Pliocene and Pleistocene volcanic rocks. The geothermal prospect of the PK20 region has been identified using the temperature anomalies observed on the water wells used for drinking water in the city of Djibouti. The Ambado-PK 20 exploration site is considered as a small site that is capable of producing electricity. Based on the high temperatures of the water from the wells, a prefeasibility study plan for this area was developed. The targeted area presents several types of geological formation: the basalt of the gulf bound with the opening of Tadjourah, the basalt of Dalha in the south in the massive "BourOugoul" and the basalt of Somali in the south-east and the Rhyolite of Mabla. On the whole, the study area is structured by normal faults that follow the direction of extension of the Gulf of Tadjourah. The tectonic structure is expressed by 3 families of faults which are the N80 ° faults at 120 ° almost E-W, the N10 ° almost N-S faults and the N60 ° and N150 ° faults. The contact between these geological formations and tectonic fabrics is related to the opening of the Gulf of Tadjourah. These anomalies are, particularly, more observed on the northern part of the aquifer in the borehole region of PK20 and Awrofoul with temperatures ranging between 40 ° C and 61.4 ° C. The intersection of the major N-S and E-W trending faults can explain the anomalous temperatures recorded inside these water wells. The wells that are present higher temperatures are located closer to the junction of these faults.

        Topic: Geology Paper Number: 12006

         Session 8P: Poster 2 [Tuesday 11th May 2021, 11:00 pm] (UTC-8)
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