This work presents the results from a multidisciplinary study carried out in the southern branch of the Larderello geothermal field (Travale-Montieri area) that is based on the integration of field data with information of the deeper structures as derived from interpretation of seismic reflection profiles and the P-T-t history of the metamorphic substratum as reconstructed from borehole data. Our data document that the structural and metamorphic signature of the metamorphic substratum is chiefly related to a prograde HT/LP metamorphic overprint, spanning in age from c. 2.8 to 0.7 Ma. The metamorphic climax was attained within the K-feldspar zone and equilibrated at P-T conditions of about 650°C (garnet-biotite thermometry) and 0.2 GPa (andalusite stability field). We interpret these new findings as the evidence of Pliocene-Pleistocene thermal metamorphism associated with multiple granite intrusions at shallow levels in the crust. These results (i) add strength to the interpretations emphasising the role of Neogene thermal metamorphism on the tectono-metamorphic signature of the basement rocks found at depth in the Larderello geothermal field; and (ii) provide insights on the thermal structures of the crustal section hosting the geothermal field and on the modes through which the long-lived positive thermal anomaly operated in Southern Tuscany.
Rossetti, F., F., B., I. M., V., M., B., Faccenna, C., R., F. (2008). Pliocene-Pleistocene high-T /low-P metamorphism during multiple granitic intrusions in the southern branch of the Larderello geothermal field (Southern Tuscany, Italy). JOURNAL OF THE GEOLOGICAL SOCIETY, 165, 247-262.
Pliocene-Pleistocene high-T /low-P metamorphism during multiple granitic intrusions in the southern branch of the Larderello geothermal field (Southern Tuscany, Italy)
ROSSETTI, FEDERICO;FACCENNA, CLAUDIO;
2008-01-01
Abstract
This work presents the results from a multidisciplinary study carried out in the southern branch of the Larderello geothermal field (Travale-Montieri area) that is based on the integration of field data with information of the deeper structures as derived from interpretation of seismic reflection profiles and the P-T-t history of the metamorphic substratum as reconstructed from borehole data. Our data document that the structural and metamorphic signature of the metamorphic substratum is chiefly related to a prograde HT/LP metamorphic overprint, spanning in age from c. 2.8 to 0.7 Ma. The metamorphic climax was attained within the K-feldspar zone and equilibrated at P-T conditions of about 650°C (garnet-biotite thermometry) and 0.2 GPa (andalusite stability field). We interpret these new findings as the evidence of Pliocene-Pleistocene thermal metamorphism associated with multiple granite intrusions at shallow levels in the crust. These results (i) add strength to the interpretations emphasising the role of Neogene thermal metamorphism on the tectono-metamorphic signature of the basement rocks found at depth in the Larderello geothermal field; and (ii) provide insights on the thermal structures of the crustal section hosting the geothermal field and on the modes through which the long-lived positive thermal anomaly operated in Southern Tuscany.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.