The occurrence and geodynamic significance of the volcano-sedimentary Tyros-beds (base of the Gavrovo-Tripolis unit) on Rhodes island, Dodekanese, SE Aegean

Abstract

The Archangelos volcano-sedimentary formation is described here. It outcrops at the base of the alpine Archangelos unit of Rhodes island and displays sedimentary and lithological characteristics, which allow its correlation with the Upper Paleozoic - Upper Triassic Tyros-beds, known from the base Gavrovo-Tripolis unit in Peloponnesus, Kythira and Crete. Consequently Archangelos unit is correlated with the Gavrovo-Tripolis unit. Moreover it is suggested that Tyros-beds characterize the base of the external carbonate platform of Hellenides all along the southern Hellenic Arc, from Peloponnesus through Kythira and Crete to Rhodes Island.

Implications for the Correlation of the Hellenic Nappes in Sw Aegean: The Geological Structure of the Archangelos Region, Rhodes Island

“…The density and the thickness of the carbonate intercalations is increasing towards the upper layers until its domination and contains a variety of fossils such as corals, sponges, echinoids, crinoids and brachiopods. These beds according to Lekkas et al (2002) are representing the transitional beds towards the carbonate platform of the unit, which is also confirmed by their age (Middle -Upper Triassic). It appears that the lowermost of the beds were deposited on a shoal environment while the uppermost beds under biothermal conditions (Mutti et al 1970, Harbury andHall 1988).…”

“…In the tectonic structure of the island of Rhodes a series of alpine units are involved that are distinguished from bottom to top as follows (Papanikolaou et al 1995, Lekkas et al 2002 • Lindos Unit. It consists of a cyan to black marble sequence, 400 -450 m thick that grades to red thin platy marbles (cipolline marbles) and grey calcareous phyllites and finally to metamorphosed flysch consisting of greenish schists and phyllites.…”

“…The lower one corresponds to a volcanosedimentary formation observed as a tectonic wedge within the calcareous sediments of the unit, located approximately 500-600 m southwest of the Archangelos settlement. This formation is known as the Koumouli formation (Mutti et al 1970) named after the homonymous mountain in northern Rhodes studied thoroughly by Lekkas et al (2002). It comprises of two distinct series, a lower one, which is characterized by alternations of pelites, tuffs and rarely sandstones and limestones, within which, bodies of green and purple volcanic rocks are observed in the form of altered pillow lavas, and an upper series which is characterized by alternations of pelites, sandstones and bioclastic limestones.…”

“…The Xerovouno radiolarites were deposited below CCD with depths that exceeded 2 km (Harbury and Hall 1988), while the transition to the carbonate sedimentation with calpionellidae and radiolarian in combination with the increase of carbonate beds during Cretaceous indicates a deepening of CCD level. This unit is considered to represent the eastern extension of the Pindos Unit in mainland Greece and Crete (Aubouin and Decourt 1970, Papanikolaou et al 1995, Lekkas et al 2002, Danelian et al 2001). …”