Fluid Inclusion Data from the Carboli 11 Well, Larderello Geothermal Field, Italy

Abstract

In the well "Carboli a temperature of 427 at a depth of 3328 below the ground level was measured. The well is located SW of' "San Pompeo well which reached a high temperature high pressure in the deep part ol'the geothermal field. Fluid inclusion and hydrothermal mineral data on a tourmaline found at below the ground level. indicate the presence of a high salinity (- wt% NaCl equiv.) brine ot magmatic derivation, during the early stage of the geothermal field. Estimated trapping temperatures at lithostatic pressures ranges between 440 and 455 "C. These temperatures are comparable with those by the geotherniometer Fluorine and chlorine contents of biotite are comparable with those found in biotites of hydrothermal ore deposits and associated acidic Late stage fluid inclusions are characterized by relatively low salinity (0.7-10 NaCl equiv.), trapping temperature around and the presence of small amounts of These temperature values confirm the present high temperature of the deepest part of the geotherinal field which is close to 400