The benthic foraminiferal record of Ocean Drilling Program (ODP) Site 910 can be
divided into four assemblage zones, from oldest to youngest: the Cassidulina spp. zone,
the Elphidium spp. zone, the Elphidium albiumbilicatum zone and the
Elphidium excavata forma
clavata zone. The Pliocene benthic foraminifers in the three lower zones of Site 910C,
102.8-504.7 meters below sea floor (mbsf), indicate warm conditions that cool progressively from
2.7 to 1.6 Ma. Based on the number and diversity of planktonic foraminifers and the high benthic
foraminiferal abundances, the lowermost Cassidulina spp. zone indicates the warmest
water conditions within the Pliocene at this locality. The Elphidium spp. zone of Site
910C indicates warm but cooling conditions with decreasing foraminiferal diversities and
abundances, which end with the initiation of glacial dropstones at 208.7 mbsf. The presence of
species described from Pacific deposits in both lower zones suggests a Pacific Ocean influence
during the late Pliocene at this site. However, climatic conditions change when Atlantic species
begin to dominate the uppermost Pliocene sediments. The uppermost Pliocene sediments of the
E. albiumbilicatum zone indicate glacial-marine conditions with warm episodes.
The uppermost E. exacavatum f. clavata, zone (0-102.8 mbsf), of Quaternary age, records glacial and interglacial climatic fluctuations, including one or more instances of grounded glacial ice (or episodes of severe ice-rafting) and ice-free interglacial deposits.
It appears to be possible to correlate the Pliocene benthic foraminiferal assemblages in Hole 910C with the isolated pockets of Arctic Pliocene sediment that have been previously described (Brouwers et al., 1991; Brigham-Grette and Carter, 1992; Feyling-Hanssen, 1990; Feyling-Hanssen et al., 1982).
Date of initial receipt: 1 July 1995
Date of acceptance: 12 December 1995
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