Geosite: Duidduru fossiliferous quarry

A fossilized tropical sea at your feet

Geosite: fossiliferous quarry of Duidduru

In the territory of Genoni, in the 1980s, a geosite of very important geological and paleontological significance was discovered. It is well known that Sardinia has, in different areas of its territory, valuable fragments of its geological history. A present-day tropical setting can help us imagine what Duidduru might have looked like in the Miocene; the stratigraphy of the site and the wealth of fossils present are some of the elements that make the site scientifically interesting. The work of paleontologists and geologists from the Superintendence for Archaeological Heritage of Sassari and Nuoro and professors from the Department of Earth Sciences at the University of Cagliari has enabled the reconstruction of the Miocene environment.

Geological formation and development

The Duidduru Formation represents the beginning of the "1st Miocene Sedimentary Cycle" Auct. in the examined territory, where it outcrops with a thickness of about 50 meters. It rests locally on the Paleozoic granitic basement, or on the Triassic limestone-dolomitic formation or, again, on Oligocene ignimbrites. It is a terrigenous succession consisting of arenitic and conglomeratic lithologies outcropping to the northeast (Arroleddu, N.ghe Addori, Pizzu Antoni Orrù, Sa Roia Manna) and west of Genoni (N.ghe Perdaligieri, Sedda Quaddaris, Duidduru). In the locality of Duidduru, in particular, the eponymous and significant geo-paleontological site equipped for the enhancement and protection of the rich fossiliferous heritage contained in the strata of this geological formation has been established. Arenites vary in grain size from medium to fine, and are either incoherent or compact according to the lesser or greater presence of carbonate cement; color varies from light hazel to greenish brown. They are generally massive, although locally pseudostratification is recognized. Constant is the presence of a volcanogenic component (tufitic arenites), likely derived from concomitant submarine magmatic activity of the andesitic type, moreover well known in Marmilla (Maccioni, 1969; 1974) and referable to the "Upper Basal-Intermediate Lava Sequence" or "Upper Andesitic Series" Auct. In its lower and middle parts the formation appears poor in macrofossiliferous component, while in its middle-upper parts very rich levels are distinguished, especially of Mollusks and Echinoids. In the locality of Duidduru and on the slopes on the hydrographic left of the Riu Scraccadrixius, a compact, hazel-colored, carbonate-cement arenitic bench is characterized by the remarkable abundance of macrofossils (shells and internal patterns), both whole and in fragments, represented by Echinoids (Clipeasteridae and Scutellidae), Bivalves (Pettinidae and Veneridae) and rare Gasteropods. These marine faunas exhibit a chaotic arrangement indicating mass submarine transport. In the Duidduru localities, near Funtana Populis, below N.ghe Perdaligieri and southwest of N.ghe Domu 'e Birni, outcrops a fine-grained arenitic bench, 70 cm to 2.5 m, consisting of granules of Paleozoic schistose lithologies with abundant volcanic component, incoherent and massive, which is distinguished both by its greenish-brown coloration and, above all, by a remarkable abundance of fossils, represented mainly by calcitic Turritellids and rare Ostreids (both whole and in fragments).

The Geosito today

The site is like an open-air museum, rich in geological and paleontological information. The rich stratigraphy presents several events that occurred in the Miocene. A fossilized seafloor, rich in artifacts, can be admired; in the central part is a shoal of turritellas, the result of the meeting of sea and river, which created a lagoon. The wall also has two interesting evidences of an earthquake that occurred in Sardinia about 5 million years ago: an exposed fault and Neptunian strands.

Enhancement of the Fossil Quarry - Now Geosite

The Superintendence for Archaeological Heritage of Sassari and Nuoro, the Department of Earth Sciences of the University of Cagliari, and the Genoni Municipal Administration have been strongly committed to ensuring that the site does not deteriorate. The acquisition of the site by the Municipality of Genoni allowed the area to be demarcated to facilitate the work of paleontologists and geologists. The 'importance of the Duidduru site necessitated its enhancement, which was sanctioned in 2011 with an agreement between the Ministry of Cultural Heritage and the Municipality of Genoni.

Discovery and recovery of fossils from the Geosite

The massive presence of sandstone in the Duidduru area had already tipped off fossil experts to a probable presence of artifacts in the area. In the 1980s, during quarry work to extract sandstone from the ground, early fossil beds were unearthed. This discovery led to the closure of the sedimentary rock extraction work, and the beginning of the study of the site by the Superintendence for Archaeological Heritage of Sassari and Nuoro and the Department of Earth Sciences of the University of Cagliari. Thanks to the work of paleontologists and geologists, an important site concerning the Miocene Era has been discovered. Various levels of stratigraphy, the presence of numerous fossil finds, different paleoenvironments have been unearthed and can be admired by visitors.

Fossil finds from the Quarry

The fossils in the area date back to the Miocene; the finds belong to marine animal species that still live in shallow tropical waters. Their fossilization occurred by mineralization, and thanks to the sandstone, the fossils were excellently preserved. Some artifacts have been taken and studied; after a cleaning process by paleontologists from the Soprintendenza per i Beni Archeologici di Sassari and Nuoro, the fossils can be seen in the P.AR.C. exhibition hall.

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