RADIOLARIAN ASSEMBLAGES FROM THE CHERTS LINKED TO THE BASALTS IN THE OTHRIS AREA (GREECE)

In the Othris region, Greece, at the top of the Pelagonian sedimentary series, Three ophiolitic units crop out, in tectonic contact: 1 - "Lower Unit", comprising two subunits: at the base the "Agoriani Melange", with blocks of ocean- and continent-derived rocks, among which MORB and IAT volcanics occur; at the top the "Fourca Subunit", consisting of altered pillow lavas topped by red cherts; 2 - "Middle Unit", composed of serpentinized harzburgites with dunite bodies and amphibolite slivers at the base; 3 - "Upper Unit", consisting of plagioclase Iherzolites. The whole thrust pile system is unconformably covered by Upper Cretaceous limestones, a Paleocene flysch and Oligocene-Miocene molasse. We collected chert samples for radiolarian biostratigraphy and basalts for geochemistry analyses in the Lower Unit in the Fourca Subunit and in blocks included in the underlying Agoriani Melange. The preliminary radiolarian biostratigraphical data and geochemical results point to a Triassic (probably late) age for the MOR basalts. They indicate, as previously found in other Dinaric-Hellenic areas (Mirdita Zone, Albania; Pindos, Argolis, Greece, etc.), the presence of a Triassic Tethyan ocean basin. No biostratigraphicat age we have obtained so far, related to the IAT rocks of the melange which, however, all along the Dinaric-Hellenic chain begin during the Middle Jurassic