Late Miocene to PleistoceneGloborotalia(Foraminiferida) from DSDP Leg 29, Site 284, Southwest Pacific

Abstract

DSDP Site 284 recovered the most complete sequence so far of Late Miocene to early Pleistocene calcareous biogenic sediments in the cool subtropical Southwest Pacific. The sequence of 20 Globorotalia species and subspecies matches that in the East Coast Basin in New Zealand and permits good biostratigraphic correlation between oceanic and shelf sequences.A new species, Globorotalia pliozea, and a new subspecies, G. conomiozea mons, are described.There is no obvious correlation between the sequence of changes in preferred coiling directions in different species.

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“…Entre las primeras destacan G. conglobatus (Cita y Ryan, 1978;Thunell, 1981;Sierro et al, 1983;Berggren, 1984), G. elongatus (Catalano y Sprovieri, 1971;Montenat y Bizón, 1976;González Donoso y Serran.o,. 1977), Globorotalia conomiozea (Catalano y SprovlOn, 1971;Ryan et al, 1974;Hornibrook, 1982) y Globorotalia plesiotumida (Blow, 1969;Berggren, 1984). Entre las que se extinguen se considera especialmente significativa G. dehiscens (Berggren, 1973(Berggren, , 1977(Berggren, , 1984, cuya presencia esporádica en esta zona denota igualmente la proximidad al límite Mioceno-Plioceno (Scott, 1983).…”

Planktonic foraminiferal biostratigraphy (Altonian‐Tongaporutuan Stages, Miocene) at DSDP Site 593, Challenger Plateau, Tasman Sea

“…Generally, most attention was given to the distribution of globorotalid taxa, and their data may be more reliable than those for globigerine taxa. On the basis of data from nearby DSDP Site 284 (Hornibrook 1982), the upper boundary of the Tongaporutuan Stage is probably significantly above core 22. Globoquadrina dehiscens persistent, typical up to extinction The preceding interpretations suggest that the base of the Tongaporutuan Stage at Site 593 is closely below core 34-1-67.…”

“…Core 22 corresponds to the lowest strata recovered from the adjacent Site 284. The upper Miocene-Quaternary planktonic foraminiferal biostratigraphy of Site 284 has been thoroughly studied by Jenkins (1975), Kennett & Vella (1975), Malmgren & Kennett (1981), and Hornibrook (1982).…”

Methods

“…Abbreviations for genera and species qualifiers are given in Table T5. Species concepts are primarily based on Hornibrook (1981Hornibrook ( , 1982, Hornibrook et al (1989), Scott et al (1990), Hornibrook and Jenkins (1994), and Crundwell and Nelson (2007 During the shipboard examination of samples for planktonic foraminifers, the abundance of foraminifers, bolboformids, and other fossil groups in the 150-1000 µm grain-size fractions of washed microfossil samples was categorized as follows:…”