Indagini Bio-Chemostratigrafiche di successioni tetidee al limite Norico/Retico Triassico Superiore.

We have investigated in detail two Upper Triassic sections from tethyan realm, PignolaAbriola and Pizzo Mondello sections, under bio- and chemostratigraphical point of view. Because of a very refined conodont biostratigraphical study, it has been possible to compare the isotopic curves of carbon and oxygen derived from geochemical analyses carried out from total rock samples of both the studied sections. The similarity of the δ13C curve trends allowed to exclude a possible diagenetic control on the original isotopic signal, at least for the carbon signal, confirmed also by the cross-plot statistical analysis. The carbon isotopic signal should be thus considered original in both the studied sections. At Pizzo Mondello, carbon show mean values from 2,00‰ to +1,00‰, a little heavier in respect to those of Pignola-Abriola, ranging from +1,50‰ to 0,50‰, in average. At Pignola-Abriola section a reduction of heavy carbon isotopic values has been observed form late Norian (+1,50‰) to the Norian/Rhaetian boundary (+0,50‰), followed by an increase of carbon values towards the end of Rhaetian (+1,50‰). Similar trend has been recorded at Pizzo Mondello section. This negative perturbation of carbon isotopic values seems similar in both section for a values of -1,00‰.