Late Pliocene to middle Pleistocene extinctions of deep-sea benthic Foraminifera ("Stilostomella extinction") in the Southwest Pacific

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doi: 10.2113/32.3.274
Author(s): Hayward, Bruce W.
Author Affiliation(s): Primary:
University of Auckland, Department of Geology, Auckland, New Zealand
Volume Title: Journal of Foraminiferal Research
Source: Journal of Foraminiferal Research, 32(3), p.274-307. Publisher: Cushman Foundation for Foraminiferal Research, Ithaca, NY, United States. ISSN: 0096-1191 CODEN: JFARAH
Note: In English. Includes appendices. 157 refs.; illus., incl. sects., 3 plates, 5 tables, sketch maps
Summary: The last major turnover in deep-sea benthic foraminifera (the Stilostomella extinction) is documented in detail in six DSDP and ODP sites around New Zealand, South-west Pacific. This was the final phase in the progressive decline of elongate, cylindrical taxa (mostly stilostomellids, pleurostomellids and uniserial nodosariids), which reached their greatest relative abundance in the late Eocene, and exhibited major declines during periods of global cooling around the Eocene-Oligocene boundary, in late middle Miocene, and through the late Pliocene to middle Pleistocene. The Stilostomella extinction includes the extinction of all elongate species with cribrate (Chrysalogonium, Cribronodosaria), slit lunate, hooded with two teeth. (Pleurostomellidae), or secondarily toothed, necked (Stilostomellidae) apertures. Elongate and uniserial benthic foraminifera are separated into: an Extinction Group (53 taxa, including several elongate agglutinated and uvigerine forms, that became extinct in the South-west Pacific during the late Pliocene-middle Pleistocene); a Die-back Group (8 species that dramatically declined in abundance but survived to the Recent); and a Survivor Group (88 mostly rare species of uniserial nodosariids with little recognised decline). In the South-west Pacific, the absolute abundance of the Extinction and Die-back groups began to decline in the late Pliocene. The decline became more dramatic during the late early and middle Pleistocene (1.2-0.7 Ma). The rate of decline was pulsed, with major declines usually associated with the onset of cold intervals, and partial recoveries in intervening warm intervals. The pulses varied in timing between sites. The highest occurrences (HOs or local disappearances) of individual Extinction Group species are variable and mostly diachronous between sites. There was a progressively increasing overall rate of local disappearances per time through the late Pliocene (onset of northern hemisphere glaciation) to the middle Pleistocene climatic revolution, with the peak period of local disappearances (mostly 0.9-0.7 Ma) up to 0.5 Ma earlier at deeper and cooler water locations. The youngest occurrence of any member of the Extinction Group (Stilostomella extinction datum) is remarkably consistent in all sites (0.65-0.57 Ma). The timing of these abundance declines, highest occurrences (or withdrawals) and extinctions was essentially the same as in the Atlantic Ocean. The precise mechanistic cause of the Stilostomella extinction (cooling, increased oxygenation of bottom waters, food supply changes) is yet to be resolved. This study reveals a much larger extinction of taxa than previously recorded (middle Pleistocene extinction rate of 23% of the bathyal-upper abyssal fauna/myr). Becoming extinct, or virtually so, during this period were at least two families (Stilostomellidae, Pleurostomellidae), one subfamily (Plectofrondiculariinae), at least 17 genera (Awhea, Chrysalogonium, Cribronodosaria, Ellipsoglandulina, Ellipsopleurostomella, Ellipsopolymorphina, Haeuslerella, Mucronina, Myllostomella, Nodosarella, Orthomorphina, Parafrondicularia, Pleurostomella, ?Rectuvigerina, Siphonodosaria, Stilostomella, Strictocostella) and 53 species. Their taxonomy is reviewed, revealing many synonymies, often going back to Schwager's (1866) pioneering study of Pliocene deep-sea foraminifera of Car Nicobar, Indian Ocean. A revised generic subdivision of the Stilostomellidae is proposed based primarily on apertural features, and Myllostomella n. gen. described.
Year of Publication: 2002
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Australasia; Benthic taxa; Cenozoic; Cores; DSDP Site 593; DSDP Site 594; Deep Sea Drilling Project; Deep-sea environment; Extinction; Faunal list; Foraminifera; IPOD; Invertebrata; Leg 181; Leg 90; Lower Pleistocene; Marine environment; Microfossils; Middle Pleistocene; Morphology; Neogene; New Zealand; ODP Site 1119; ODP Site 1120; ODP Site 1123; ODP Site 1125; Ocean Drilling Program; Pacific Ocean; Paleoecology; Plectofrondiculariinae; Pleistocene; Pleurostomellidae; Pliocene; Protista; Quaternary; South Pacific; Southwest Pacific; Stilostomella; Stilostomellidae; Synonymy; Taxonomy; Tertiary; Upper Pliocene; West Pacific
Coordinates: S403029 S403028 E1674029 E1674028
S453129 S453128 E1745653 E1745652
S444520 S444520 E1722336 E1722336
S500349 S500349 E1732218 E1732218
S414710 S414710 W1712956 W1712956
S423259 S423259 W1780959 W1780959
Record ID: 2002067084
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