Geology and tectonic setting of the Fornovolasco area, Alpi Apuane (Tuscany, Italy)

Abstract

The study area is located in the Alpi Apuane (Tuscany, Italy), and extends between N 44°0 ′ 49.883 ′′-E 10°20 ′ 23.467 ′′ (SW corner) and N 44°2 ′ 53.403 ′′-E 10°23 ′ 19.175 ′′ (NE corner). The area shows a pile of tectonic units belonging either to the Apuane metamorphic complex, and Tuscan Nappe, stacked during the Alpine orogeny. The latter is represented by a sedimentary Triassic-Miocene succession, and it is characterized by a large-scale east-dipping monocline, with local excision of stratigraphic terms due to the occurrence of intra-unit lowangle normal faults. The Apuane metamorphic complex is formed by Paleozoic phyllites, post-Variscan magmatic rocks (Fornovolasco Metarhyolite Fm.), and Mesozoic-Tertiary metasedimentary formations. The 1:5000 scale geological map and the cross-sections illustrate the tectonic setting of the Fornovolasco area, resulting from the Tertiary tectonometamorphic events. In the Fornovolasco area, small Tl-rich pyrite + magnetite ore bodies occur close to the contacts between the Paleozoic basement and the cover metasedimentary formations.

Permian Hydrothermal Alteration Preserved in Polymetamorphic Basement and Constraints for Ore-genesis (Alpi Apuane, Italy)

“…The Massa Unit consists of a Paleozoic metasedimentary and metavolcanics basement and an upper Permian-Upper Triassic metasilicoclastic succession (Figure 1; e.g., [16,17]). The Apuane Unit includes a litho-stratigraphic sequence made up of a Paleozoic basement (e.g., [18]) intruded by post-Variscan magmatic rocks (Fornovolasco Metarhyolite Fm; [19][20][21]), unconformably overlain by an Upper Triassic-Oligocene metasedimentary succession (Figures 1 and 2; e.g., [16]).…”

“…In the southern Alpi Apuane, a peculiar tourmalinite-bearing facies, spatially associated with orebodies, has been referred as the "Fornovolasco Schists" Fm; it was attributed to a different lithostratigraphic unit (e.g., [34]). However, this interpretation has been strongly debated (e.g., [19]). A Cambrian-early Ordovician depositional age of the "Filladi inferiori" Fm was proposed through the correlation with the Paleozoic successions of Sardinia (e.g., [18,35]); this dating was recently confirmed by Paoli et al [36] and Pieruccioni et al [37], who suggested a depositional age between early Cambrian and middle-late Ordovician times, based on LA-ICP-MS U-Pb zircon data.…”

“…The Fornovolasco Metarhyolite Fm is formed by fine-grained massive subvolcanic rocks with a granular to porphyritic texture, locally showing the widespread occurrence of cm-sized tourmaline + quartz orbicules [19,20]. On the basis of LA-ICP-MS U-Pb zircon dating, Vezzoni et al [20] dated this formation to Permian (c.a.…”

Monitoring of Strain and Temperature in an Open Pit Using Brillouin Distributed Optical Fiber Sensors

“…First described by [23], the Apuan Alps complex, composed by the Massa and Apuan tectono-metamorphic units, is interpreted as result of two main tectonic phases known as "D1" and "D2" [15,[24][25][26][27][28]. The first is a ductile compressional event (late Oligocene-very early Miocene), which originated from a progressive deformation with intense foliation [29]. The second, a ductile extensional occurrence dating back to the early Miocene, produced both folds and high-strain shear zones [29].…”

“…The first is a ductile compressional event (late Oligocene-very early Miocene), which originated from a progressive deformation with intense foliation [29]. The second, a ductile extensional occurrence dating back to the early Miocene, produced both folds and high-strain shear zones [29].…”