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Planktic foraminiferal biostratigraphy and 87 Sr/ 86 Sr isotopic stratigraphy of the Oligocene-to-Pleistocene sedimentary sequence in the southeastern Calabrian microplate, southern Italy

1995; Cambridge University Press; Volume: 69; Issue: 1 Linguagem: Inglês

10.1017/s0022336000026871

1937-2337

R. Timothy Patterson, John Blenkinsop, William Cavazza,

Geological and Geophysical Studies Worldwide

Integration of foraminiferal biostratigraphy, 87 Sr/ 86 Sr isotope stratigraphy, and traditional physical stratigraphy has provided a refined age control of a poorly known Oligocene-to-Pleistocene sedimentary sequence nonconformably covering the crystalline basement complex of the Calabrian microplate, a continental block which rifted off the southern margin of the European plate during Neogene time. In spite of the fossil-poor content of the sequence, the simultaneous use of paleontological and geochemical techniques have resulted in the following conclusions. 1) The age of an unnamed, thin calcarenite unit locally present at the base of the sequence, previously considered Rupelian to early Aquitanian in age, has been refined to Chattian (27.8–24.8 Ma). This calcarenite was considered a basal, conformable member of the overlying Stilo-Capo d'Orlando Formation. However, this study indicates that it is separated from the Stilo-Capo d'Orlando Formation either by an angular unconformity or by a disconformity representing a significant time interval. 2) The Stilo-Capo d'Orlando Formation has a latest Chattian–earliest Aquitanian to Burdigalian age. Previously published reports suggested deposition over a much longer time span, ranging from late Rupelian to Langhian. 3) An unnamed deep-marine siliciclastic unit mostly composed of conglomerate and sandstone and previously considered Tortonian in age is, in fact, Serravallian to Tortonian. 4) The depositional interval of the “trubi,” fine-grained marine deposits, has been independently confirmed to span the Pliocene-Pleistocene. The results of this study provide a framework for future sequence–stratigraphic and paleotectonic studies in the area, and prove the effectiveness of an integrated paleontological and geochemical ( 87 Sr/ 86 Sr) approach in the study of fossil-poor sedimentary sequences.