Age variation in the source of the diapiric mud breccia along and across the axis of the Mediterranean Ridge Accretionary Complex

Abstract

Pleistocene, or younger, mud diapirism is recorded along the arcuated crest of the Mediterranean Ridge Accretionary Complex over a distance of more than 450 km. The extruded mud-supported breccia, named mud breccia, is poorly fossiliferous, but the matrix may be dated as Late Aptian to Albian and Late Burdigalian to Langhian in age based on the calcareous plankton content. Calcareous nannofossils and planktonic foraminifera diagnostic of other ages are sparse within the two above-mentioned major assemblages. They indicate the presence of sediments attributable (1) to the Santonian and Cenomanian which occur in association with the mid-Cretaceous assemblages (Toronto, Unnamed, and Aros Domes), and (2) to the Serravallian which occur in association with the Late Burdigalian-Langhian assemblages in the Gelendzhik Dome. Aptian-Albian to Late Cretaceous sediments are pelagic in origin and are similar to the Scisti a Fucoidi and Scaglia Rossa Formations well known from continental Italy. Mixed dolomitic clasts and crystals also occur within the matrix, indicating the presence of portions of the evaporitic sequence of Messinian age in four cores from the western locations. Single, very rare plankton specimens, indicative of other ages different from those mentioned above, also occur within the matrix at various places. They are interpreted as reworked primarily within the Late Burdigalian-Langhian sediments. The age of the emplacement of the breccia should be older than the Middle Pleistocene as supported by the occurrence of clasts of this age in the mud breccia and is still an ongoing process at least in the Napoli Dome.