A geochemical reconnaissance of the Alid volcaniccenter and geothermal system, Danakil depression, Eritrea

Geological and geochemical studies indicate that a high!temperature geothermal system underlies the Alid volcanic center in the northern Danakil depression of Eritrea[ Alid is a very late!Pleistocene structural dome formed by shallow intrusion of rhyolitic magma\ some of which vented as lavas and pyroclastic ~ows[ Fumaroles and boiling pools distributed widely over an area of 09km1 on the northern half of Alid suggest that an active hydrothermal system underlies much of that part of the mountain[ Geothermometers indicate that the fumarolic gases are derived from a geothermal system with temperatures 114>C[ The isotopic composition of condensed fumarolic steam is consistent with these temperatures and implies that the source water is derived primarily from either lowland meteoric waters or fossil Red Sea water\ or both[ Some gases vented from the system "CO1\ H1S and He# are largely magmatic in origin[ Permeability beneath the volcanic center may be high\ given the amount of intrusion! related deformation and the active normal faulting within the Danakil depression[ Published by Elsevier Science Ltd on behalf of CNR[ All rights reserved[