Monte Argentario, Grosseto Province, Tuscany, Italyi

Regional Level Types
Monte Argentario	Commune
Grosseto Province	Province
Tuscany	Region
Italy	Country

Monte Argentario is a municipality and a peninsula (promontory), located about 35 kilometres SSE of Grosseto. The municipal territories of Monte Argentario includes also three islets lying off the cost of the promontory: Isola Argentarola, Isola Rossa, and Isolotto di Porto Ercole.

The promontory, jutting out into the Tyrrhenian Sea, stretches towards the two southernmost islands of the Tuscan Archipelago, Giglio and Giannutri. Monte Argentario was an island in the past, but the sea currents and the Albegna River joined it with the mainland through two so-called tombolos (narrow pieces of land), the Tombolo of Giannella and the Tombolo of Feniglia, which formed the Orbetello Lagoon. The highest point of the peninsula is Punta Telegrafo (635 m a.s.l.).

From a geological and mineralogical point of view there are significant differences between the the east-central and the western part of the promontory.

The central and eastern part of the Monte Argentario Promontory mainly consists of rocks belonging to two geological units, Tuscan Verrucano (Mid-Triassic metamorphosed continental clastic rocks) and Calcare Cavernoso (essentially a “pitted” calcarous rock of grey colour), with minor occurrences of Palaeozoic metasediments.

The western part of the promontory forms a tectonic melange (having affinity with the tectonic pile of the Franco Promontory on the Island of Giglio) comprising a large variety of rock types, many of which are not found further east. The Triassic sequence is represented by psammopelitic Verrucano, dolomitic marble (“grezzoni”) and gypsum ("Burano Anhydrite"). In addition, abundant Triassic calcite marble is present (the marble sequence has been given the local name “Cala Piatti unit”). Interlayered calcareous beds and phyllites are considered as being transitional in facies between pelitic Verrucano and the calcite marble unit. A strongly fragmented ophiolite unit forms a substantial part of the western Argentario melange. Rock types of this unit include ultramafic rocks (mainly serpentinite, locally talc-tremolite rock and pyroxenite), metagabbro, metabasalt, and metasedimentary rocks of oceanic provenance. Furthermore, there are minor occurrences of metasedimentary rocks (siliceous-calcareous rocks, greywacke, etc.).

Verrucano rocks contain low-grade metamorphic minerals such as pyrophyllite, sudoite, chloritoid, and Fe-Mg-carpholite (Theye et al., 1997; Jolivet et al., 1998). These minerals have been used to characterise metamorphism and constrain P-T paths. The discovery of ferro- and magnesiocarpholite (XMg = Mg/(Mg+Mn+Fe2+) = 0.36 - 0.70) demonstrated that the Verrucano sequence of the east-central Monte Argentario had experienced HP-LT conditions similar to those derived from metabasites in the west (Theye et al., 1997).

Fossils

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Other Databases

Wikipedia:	https://en.wikipedia.org/wiki/Monte_Argentario
Wikidata ID:	Q214731
GeoNames ID:	3173038

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References