Stratigraphic and tectonic study of Larderello-Travale basement rocks and its geothermal implications
Abstract One objective of geothermal research in intensely exploited vapour-dominated fields is the individuation of deeper productive horizons. For this purpose a stratigraphic and tectonic study has begun on the so-called “basement” in Larderello-Travale area. Paleozoic and Triassic formations have been distinguished. The tectonic setting shows the presence of folding structures and wedges separated by overthrust surfaces where the rocks may be fractured and productive. Comparisons between the Triassic-Paleozoic series of this area and those in the rest of Tuscany and the Southern Alps suggest two hypotheses on the possible presence of potential carbonate reservoirs at depths below the present deepest wells ( ca. 2700 m). In the first hypothesis the whole Paleozoic and Triassic clastic series is allochthonous and underlain by the Apuan Alps “Autochthon”, comprising Mesozoic carbonate rocks. In the second hypothesis, considering autochthonous the deepest part of the clastic series, these may be underlain by Silurian-Lower Carboniferous carbonate formations. Both these hypotheses should be confirmed by geophysical research before passing to deeper exploration.