Geoturism Balearic Islands

As is well known, Mallorca is not a volcanic island, but this does not mean that there are no volcanic rocks in its geological record. In fact, they are very characteristic (although not exclusive) of the Upper Triassic (237-201 Ma).

One of the best places for observing the Triassic volcanic rocks, interspersed between sedimentary rocks, is in the slopes of the road that descends to Cala Tuent, which display two clearly differentiated sections:

-         A base part, called the “Lower red unit,” which corresponds to the Keuper stratigraphic unit and reflect the specific environmental conditions in which they were formed.</p><p><br></p></div>">facies of the Upper Triassic and is characterised by a predominance of gypsums and lutites of various colours (normally red-maroon). It corresponds to a system of salt lakes in a very arid climate.

-         Above it, the Felanitx Formation, composed of very varied materials (dolomites, breccias, carnelians, marls, etc.) which were mostly deposited in a shallow marine environment.

At Cala Tuent, the Felanitx Formation is the most interesting in scientific terms, being considered the best tectonic, eustatic or antropical processes</span></p></div>">outcrop for observing the scarce record of volcanic rocks contained in this formation.

The most abundant volcanic rock in both series is igneous rock of maphic composition (rich in silicates of magnesium and iron and in silica) composed mainly of plagioclase and pyroxene.</p></div>">basalt and the most characteristic mineral is olivine. In this area we also find pyroclastic deposits, which are a direct product of volcanic eruptions. In addition, there are levels with a mixture of volcanic and sedimentary rocks, named volcano-sedimentary. One of the rocks of this category is tuffite, formed by the erosion of the pyroclastic deposits and their subsequent mixing with sediments; and sedimentary rock which is formed when lava comes into contact with wet sediments, cooling abruptly. The result is similar to that of breccias, in which the fragments correspond to igneous rocks and the matrix to sedimentary rocks.&nbsp;&nbsp;</p></div>">peperite, originated by the contact of lava with moist sediments.

By means of chemical analyses we can determine that the vulcanism present in Cala Tuent is of a basic character (it contains a low percentage of silica) and is of an intraplate type: that is to say, the magma originates from the melting of the stratum beneath a tectonic plate