PUMA
Istituto di Geoscienze e Georisorse     
Carella M., Fulignati P., Musumeci G., Sbrana A. Metamorphic consequences of neogene thermal anomaly in the northern Apennines (Radicondoli-Travale area, Larderello geothermal field - Italy). In: Geodinamica Acta, vol. 13 (6) pp. 345 - 366. Taylor and Francis, 2000.
 
 
Abstract
(English)
In the Radicondoli–Travale area of the Larderello geothermal field (Italy) new structural and petrologic data on some metamorphic units, cored from geothermal wells, reveal the existence of a wide complex of hornfels rocks. The development of the complex is related to the emplacement of Neogene magmatic rocks at a shallow depth within a Permo–Triassic terrigenous metasedimentary sequence of a low metamorphic grade. The sequence was subjected to alpine tectonic-metamorphic events. This reconstruction gives new insights in the tectonic setting of metamorphic units below the Tuscan Nappe, in southern Tuscany. Particularly, the medium and high grade metamorphic rocks seem strictly related to the development of Neogene thermal aureoles and do not represent remnants of a Paleozoic basement. Furthermore, in this sector of the Larderello geothermal system, the presence of deep geothermal reservoir at a depth of 3 000 m is mainly linked to the enhanced permeability caused by fracturing in these hornfels rocks. This fracturing is a consequence of the dehydration reaction occurring in the metapelites due to Neogene thermal metamorphism. This mechanism allowed the development of a long-lived hydrothermal system, shown by the secondary mineralogical assemblages. These testify the presence of at least two hydrothermal stages which are well preserved in the less permeable units.
URL: http://www.tandfonline.com/loi/tgda20
Subject Larderello geothermal field
northern Apennines
tectono-metamorphic evolution
Alpine orogenesis
neogene magmatism
Italy


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