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Hydrothermal fluid evolution in the 'Botro ai Marmi' quartz-monzonitic intrusion, Campiglia Marittima, Tuscany, Italy; evidence from a fluid-inclusion investigation

Paolo Fulignati
Hydrothermal fluid evolution in the 'Botro ai Marmi' quartz-monzonitic intrusion, Campiglia Marittima, Tuscany, Italy; evidence from a fluid-inclusion investigation
Mineralogical Magazine (October 2018) 82 (5): 1169-1185

Abstract

The quartz-monzonitic intrusion of 'Botro ai Marmi' in Tuscany, Italy, can be considered to be a typical example of an intrusion-centred magmatic hydrothermal system. The evolution of hydrothermal fluids in the 'Botro ai Marmi' intrusion was investigated using fluid-inclusion analyses to provide suitable physico-chemical constraints on the fluids involved in the late- to post-magmatic hydrothermal activity that affected the intrusion, providing inferences on their origin and variations of temperature and pressure with time. This work demonstrates that the earliest fluids circulating in the 'Botro ai Marmi' intrusion were high-temperature brines exsolved directly from the crystallizing magma. This fluid circulated in the intrusion under lithostatic conditions (P > 90 MPa, T > 540 degrees C). A second evolutionary stage of the magmatic hydrothermal system is marked by the transition from lithostatic (>90 MPa) to hydrostatic dominated conditions (50 to 10 MPa). In this stage the fluids are also interpreted to be mainly orthomagmatic in origin but unmixed in a high-salinity brine and in a low-salinity vapour aqueous phase, at a temperature ranging from approximately 500 to 300 degrees C. These fluids were responsible for the potassic alteration facies. At a later stage of hydrothermal evolution, abundant meteoric dominated fluids entered the system and are associated with propylitic alteration. This event marks the transition from a magmatic-hydrothermal system to a typical hydrothermal ('geothermal') system, which can be assumed to be similar to some extent to the nearby active high-enthalpy geothermal system of Larderello. Low-temperature and low-salinity meteoric water-dominated fluids characterize the latest stage of the 'Botro ai Marmi' hydrothermal system.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 82
Serial Issue: 5
Title: Hydrothermal fluid evolution in the 'Botro ai Marmi' quartz-monzonitic intrusion, Campiglia Marittima, Tuscany, Italy; evidence from a fluid-inclusion investigation
Author(s): Fulignati, Paolo
Affiliation: Universita di Pisa, Dipartimento di Scienze della Terra, Pisa, Italy
Pages: 1169-1185
Published: 201810
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 61
Accession Number: 2019-003791
Categories: Igneous and metamorphic petrologyEconomic geology, geology of energy sources
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch maps
N42°00'00" - N44°00'00", E10°00'00" - E12°00'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201904
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