BRECCE SINSEDIMENTARIE NELLA SUCCESSIONE MESOZOICA DEL GRUPPO DEL MONTE CAIRO (LAZIO MERIDIONALE)

Abstract

During the researches being carried out in the M. Cairo Massif (Southern Lazio, Italy) the AA. observed sinsedimen­tary breccias widely outcropping on the north-eastern sector of the area. The breccias are well bedded, show a variable thicke­ness and a wedge-shaped geometry; they are made up of coarse angular fragments which are not graded, without any sorting, varyng in lithology and age. The above characters suggest a local derivation from the mesozoic sequence. The breccias overlie a substratum formed of limestones of variable age, going from the Dogger-Malm (as, for exam­ple, the Costalunga area) to Barremian (San Vincenzo and Vallone Scuro areas). Organic detrital limestones known as "Calcare sac­caroide" Auct., the age of which goes from Campanian­Mastrichtian to Paleogene, conformably lie on the brec­cias. The lithostratigraphic and biostratigraphic data so far obtained enable us to formulate some hypotheses on the age and the mechanisms by which these breccias were empla­ced.