Geology of the Platanares Geothermal Area, Copan, Honduras

Abstract

The Platanares, Copan (Honduras) geothermal area is located in a highly faulted terrain of Paleozoic(?) metamorphic rocks, and Tertiary volcanic rocks. All thermal manifestations are located along faults. The volcanic rocks are probably too old to represent the surface expression of an active crustal magma body. Thus, the thermal water is interpreted to be heated during deep circulation in a regime of elevated heat flow. The water chemistry suggests that the geothermal reservoir originates within the Cretaceous sedimentary sequence and that the reservoir temperature may be as high as 240°C. Two exploration coreholes penetrated the volcanic sequence and bottomed within Cretaceous redbeds. Well PLTG-1 is 650 m deep and flows at 3 Mw thermal from a 160° C permeable zone. Well PLTG-2 is 401 m deep and has a thermal gradient of 139° C/km. Exploration drilling is continuing, with a third corehole to be drilled in May, 1987.