Resumen de Magnetobiochronology of several Miocene Nannofossil Datums at DSDP Site 536 Revisited
Alyssa M. Peleo-Alampay, Wuchang Wei
Many of the Miocene nannofossil datum ages compiled in the used biochronology of Berggren et al. (1985) were based on the magnetobiostratigraphic correlations at Site 563. The present study reexamines five of the marker species, i.e., Sphenolithus belemnos, Sphenolithus heteromorphus, Catinaster coalitus, Catinaster calyculus, and Discoaster hamatus in Site 563 to clarify some problems with the current nannofossil biochronology. This study shows that the FO of Sphenolithus belemnos corraletes with the bottom of C6n (20.3 Ma) at 563 rather C6A (21.5 Ma) as adopted by Berggren et al. (1985). The FO of Spenolithus heteromorphus is in C5Dr or older (>18.5 Ma), in agreement with results from other sites. The age of 17.1 Ma (C5Cr) for the datum as compiled in Bergreen et al. (1985) should be now abandoned. The FO of Catinaster coalitus in Site 563 correlates with the lower part of C5n (10.0 Ma), similar to the results from several other sites, but significantly different from that (10.8 Ma, C5r) adopted by Berggren et al. (1985). The FO of Catinaster calyculus and Discoaster hamatus appear to be diachronous and the subdivision of Zone CN7 does seem to be possible in the mid-latitude North Atlantic.
