Evolution of a pluton-porphyry-skarn system: the Temperino-Lanzi mine (Campiglia Marittima, Tuscany)

The Campiglia Marittima Fe-Cu-Zn-Pb(-Ag) skarn deposit is of small size (∼ 50 kt of base metals) and medium/low-grade (1.4% Cu; 3.8% Zn; 2.0% Pb) with modest economic interest but its geological characteristics (e.g., spatial association with magmatic rocks, textural features of primary silicate minerals, ore bodies shape, etc) make it an ideal site to study skarn- and ore-forming processes. The present PhD thesis contributes to the debate on processes of skarn formation providing detailed field data integrated with petrographic, mineralogical and geochemical-isotopic data of the Campiglia Marittima magmatic-hydrothermal system. This locality offers also the opportunity to study the tridimensional shape of the geological bodies, thanks to past underground mining activities (during almost three millennia of ore exploitation), with additional data derived from about 25 km of drillholes. The results of this PhD work led to a deep review of the classical Campiglia Marittima exoskarn model and suggest an alternative holistic model for the development of skarn and ore bodies in the regional-local tectono-magmatic setting. The magmatic-hydrothermal and ore temporal sequence, together with a unifying tectonic-magmatic-metasomatic model proposed for Campiglia Marittima area can be used elsewhere as a guide in defining possible targets for ore and geothermal exploration. In addition to the scientific purposes, the results of this thesis have been and will be made availble also for tourists and laymen with no significant geological background by means of specific publications, conferences and mineralogical exhibitions, in the framework of a fruitful cooperation between the Dipartimento di Scienze della Terra (University of Pisa), the Istituto di Geoscienze e Georisorse of Pisa (CNR) and the Parchi Val di Cornia S.p.A., that manages the Parco Archeominerario di San Silvestro.