Formation of authigenic minerals and their use as indicators of the physicochemical parameters of the fluid in the Larderello-Travale geothermal field

Journal Article · Sun Aug 01 04:00:00 EDT 1982 · Econ. Geol.; (United States)

DOI:https://doi.org/10.2113/gsecongeo.77.5.1071· OSTI ID:5703773

Cavarretta, G; Gianelli, G; Puxeddu, M

Different authigenic mineral assemblages and mineral compositions have been found in different areas of the Larderello-Travale geothermal field. In the peripheral areas the most abundant authigenic minerals are quartz, calcite, chlorite, and sulfides. They formed in a temperature range of 150/sup 0/ to 250/sup 0/C and with a P /SUB co2/ range of 0.1 to 1.0 atm. In a hotter part of the field, at depths between 200 and 1,300 m, where the main productive fractures are located, the most important authigenic minerals are quartz, chlorite, calcite, K-feldspar, and K-bearing mica, with which wairakite, hematite, anhydrite, and barite are sometimes associated. Deposition of all these minerals occurs in a temperature range of 200/sup 0/ to 300/sup 0/C under P /SUB co2/ of about 1 atm, and relatively high P /SUB o2/, in fluids sometimes characterized by silica oversaturation. Below the 1,300-m depth in the hottest part of the field K-feldspar, chlorite, epidote, sulfides with minor sphene, prehnite, clinopyroxene, and clinoamphibole are present. These minerals form in a temperature range of 250/sup 0/ to 350/sup 0/C under a P /SUB co2/ of less than 1 atm and a P /SUB o2/ ranging from 10/sup -40/ to 10/sup -33/ atm and reasonably reflect the physicochemical parameters of the geothermal fluid before exploitation. Evidence of an earlier hydrothermal stage characterized by higher temperatures can be seen in the occurrence of relic wollastonite and andradite.

• Research Organization: Centro di Studio per la Geologia dell'Italia Centrale, C. N. R., Rome
• OSTI ID: 5703773
• Journal Information: Econ. Geol.; (United States), Journal Name: Econ. Geol.; (United States) Vol. 77:5; ISSN ECGLA
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150302* -- Geothermal Exploration & Exploration Technology-- Geochemical Techniques & Surveys
58 GEOSCIENCES
580400 -- Geochemistry-- (-1989)
ALKALINE EARTH METAL COMPOUNDS
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHALCOGENIDES
CHLORITE MINERALS
DEPTH
DEPTH 1-3 KM
DIMENSIONS
FLUIDS
GEOCHEMICAL SURVEYS
GEOTHERMAL FIELDS
GEOTHERMAL FLUIDS
LARDERELLO GEOTHERMAL FIELD
MINERALIZATION
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PARAMETRIC ANALYSIS
QUARTZ
SILICATE MINERALS
SILICON COMPOUNDS
SILICON OXIDES
SULFIDES
SULFUR COMPOUNDS
SURVEYS
TEMPERATURE GRADIENTS