Response of abyssal benthic Foraminifera to mid-Oligocene glacial events in the eastern Equatorial Pacific Ocean (ODP Leg 199)

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doi: 10.1016/j.palaeo.2010.03.021
Author(s): Takata, Hiroyuki; Nomura, Ritsuo; Khim, Boo-Keun
Author Affiliation(s): Primary:
Pusan National University, Marine Research Institute, Busan, South Korea
Shimane University, Japan
Volume Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, 292(1-2), p.1-11. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. Supplemental information/data is available in the online version of this article. 85 refs.; illus., incl. charts, 1 table, sketch map
Summary: We investigated Oligocene and early Miocene benthic foraminiferal faunas (>105 µm in size) from Ocean Drilling Program (Leg 199) Site 1218 (4826 m water depth and ∼3300 to ∼4000 m paleo-water depth) and Site 1219 (5063 m water depth and ∼4200 to ∼4400 m paleo-water depth) to understand the response of abyssal benthic foraminifera to mid-Oligocene glacial events in the eastern Equatorial Pacific Ocean. Two principal factor assemblages were recognized. The Factor 1 assemblage (common Nuttallides umbonifer) is related to either an influx of the Southern Component Water (SCW), possibly carbonate undersaturated, or a decrease in seasonality of the food supply from the surface ocean. The Factor 2 assemblage is characterized by typical deep-sea taxa living under variable trophic conditions, possibly with a seasonal component in food supply. The occurrence of abyssal benthic foraminifera faunas during the mid-Oligocene depends on either the effect of SCW or the seasonality of food resources. The Factor 1 assemblage was most common near 76Ol-C11r, 73Ol-C10rn and 67Ol-C9n (ca. 30.2, 29.1 and 26.8 Ma respectively by Palike et al. (2006)). This indicates that the effect of SCW increased or the seasonal input of food from the surface ocean to benthic environments was weakened close to these glacial events. In contrast, the huge export flux of small biogenic carbonate particles close to these glacial events might be responsible for carbonate-rich sediments buffering carbonate undersaturation. Changes in deep-water masses or the periodicity of food supply from the surface ocean and variation in surface carbonate production affected by orbital forcing had an impact on the mid-Oligocene faunas of abyssal benthic foraminifera around the intervals of glacial events in the eastern Equatorial Pacific Ocean. The Factor 1 assemblage decreased sharply at ∼30 Ma (29.8 Ma by Palike et al. (2006), 30.0 Ma by CK95) and returned to dominance after ∼29 Ma (28.6 Ma by Palike et al. (2006), 28.8 Ma by CK95). It is likely that the effect of SCW (possibly carbonate undersaturated) has intensified since the late Oligocene. The faunal transition of benthic foraminifera in the eastern Equatorial Pacific Ocean at ∼29 Ma might be attributable to the influence of Northern Component Water (NCW) input to the Southern Ocean and the subsequent formation of SCW at about that time. Abstract Copyright (2010) Elsevier, B.V.
Year of Publication: 2010
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Assemblages; Benthic taxa; Bioclastic sedimentation; Cenozoic; Climate forcing; Deep-sea environment; East Pacific; Equatorial Pacific; Factor analysis; Foraminifera; Glacial environment; Glaciomarine environment; Invertebrata; Leg 199; Marine environment; Microfossils; Middle Oligocene; North Pacific; Northeast Pacific; ODP Site 1218; ODP Site 1219; Ocean Drilling Program; Oligocene; Orbital forcing; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleoecology; Paleogene; Protista; Sedimentation; Statistical analysis; Tertiary; Trophic analysis
Coordinates: N074800 N074800 W1420100 W1420100
N085300 N085300 W1352200 W1352200
Record ID: 2010097124
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands