Heat flow at the Platanares, Honduras, geothermal site

Meert J .G. and Smith, D.L. , 1991. Heat flow at the Platanares, Honduras , geothermal site. In: F .Goff (Editor), Honduras A Geothermal Investigation. J. Volcanol. Geotherm. Res., 4 5 : 9 1 9 9 . Three boreholes, PLTG-1, PLTG-2 and PLTG-3, were drilled in the Platanares, Honduras geothermal system to evaluate the geothermal energy potential of the site. The max imum reservoir temperature was previously estimated at 225 240°C using various types of chemical and isotopic geothermometry. Geothermal gradients of 1 3 9 2 3 9 ° C / k m , calculated from two segments of the temperature-depth profile for borehole PLTG-2, were used to project a m in imum depth to the geothermal reservoir of 1 . 2 1.7 km. Borehole PLTG-1 exhibited an erratic temperature distribution attributed to fluid movement through a series of isolated horizontal and subhorizontal fractures. The max imum measured temperature in borehole PLTG-1 was 150.4°C, and in PLTG-2 the max imum measured temperature was 104.3°C. PLTG-3 was drilled after this study and the maximum recorded temperature of 165°C is similar to the temperature encountered in PLTG-1. Heat flow values of 392 m W m -2 and 266 m W m -2 represent the first directly-measured heat flow values for Honduras and northen Central America. Radioactive heat generation, based on gamma-ray analyses of uranium, thor ium and potassium in five core samples, is less than 2.0 #W m -3 and does not appear to be a major source of the high heat flow. Several authors have proposed a variety of extensional tectonic environments for western Honduras and these heat flow values, along with published estimates of heat flow, are supportive of this type of tectonic regime.