A multiple microfossil biochronology for the Miocene

A multiple microfossil biochronology is presented for the Miocene which allowsresolution of time approaching 100,000 years. Carbonate stratigraphy is integrated togreatly enhance this resolution. Graphical correlation techniques were applied to over20 DSDP (Deep Sea Drilling Project) sections to identify 175 planktonic foraminiferal,calcareous nannofossil, radiolarian, and diatom datum levels between 24.0 and 4.3 Mawhich show the most consistent (isochronous) correlations. Ages are estimated for thesedatum levels through 72 direct correlations to paleomagnetic stratigraphy and extrapolationbetween the correlation points. The resulting Miocene time scale resembles previouslypublished time scales except for the early Miocene, where recent paleomagneticcorrelations result in changes.The three CENOP (Cenozoic Paleoceanography Project) time slices (-21,16, and8 Ma) are characterized biostratigraphically (planktonic foraminifers, calcareous nannofossils, radiolarians, and diatoms) and in terms of carbonate stratigraphy. The ages ofthe time slices are estimated as follows: the early Miocene time slice (21.2-20.1 Ma;given as 22 Ma in this volume), the late early Miocene time slice (16.4-15.2 Ma), and thelate Miocene time slice (8.9-8.2 Ma).An alternate time scale utilizing a paleomagnetic Anomaly 5-paleomagnetic Chron11 correlation is also presented. Estimated ages for microfossil zones and datum levels inthe late middle and early late Miocene (14-7 Ma) utilizing the alternate time scale aregenerally younger than those for the more traditional time scale. The late Miocene timeslice has an estimated age of 8.0-7.0 Ma.