Unlocking the ice house: Oligocene-Miocene oxygen isotopes, eustasy, and margin erosion

Conference · Wed Apr 10 00:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

OSTI ID:5446900

Miller, K G ^[1]; Wright, J D; Fairbanks, R G ^[2]

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1. Rutgers, The State Univ. of New Jersey, New Brunswick (USA) Columbia Univ., Palisades, NY (USA)
2. Columbia Univ., Palisades, NY (USA)

Benthic foraminiferal {delta}{sup 18}O records place limits on the history of glaciation, suggesting the presence of ice sheets at least intermittently since the earliest Oligocene. The best indicator of ice growth is a coeval increase in global benthic and western equatorial planktonic {delta}{sup 18}O records. Although planktonic isotope records from the western equatorial regions are limited, subtropical planktonic foraminifera may also record such ice volume changes. It is difficult to apply these established principles to the Cenozoic {delta}{sup 18}O record because of the lack of adequate data and problems in stratigraphic correlations that obscure isotope events. The authors improved Oligocene to Miocene correlations of {delta}{sup 18}O records and erected eight oxygen isotope zones (Oi1-Oi2, Mi1-Mi6). Benthic foraminiferal {delta}{sup 18}O increases which can be linked with {delta}{sup 18}O increases in subtropical planktonic foraminifera and with intervals of glacial sedimentation on or near Antarctica. These new correlations of middle Miocene benthic and western equatorial planktonic {delta}{sup 18}O records show remarkable agreement in timing and amplitude. They interpret benthic-planktonic covariance to reflect substantial ice volume increases near the bases of Zones Mi2 (circa 16.1 Ma), Mi3 (circa 13.6 Ma), and possibly Mi5 (circa 11.3 Ma). Possible glacioeustatic lowerings are associated with the {delta}{sup 18}O increases which culminated with the bases of Zone Mi4 (circa 12.6 Ma) and Mi6 (circa 9.6 Ma), although low-latitude planktonic {delta}{sup 18}O records are required to test this. These inferred glacioeustatic lowerings can be linked to seismic and rock disconformities.

• OSTI ID: 5446900
• Report Number(s): CONF-890434-; CODEN: JGREA
• Journal Information: Journal of Geophysical Research; (United States), Vol. 96:B4; Conference: American Geophysical Union (AGU) Chapman conference on causes and consequences of long-term sea level change, Snowbird, UT (United States), 17-20 Apr 1989; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GLACIERS
VOLUME
TERTIARY PERIOD
PALEOCLIMATOLOGY
AGE ESTIMATION
ANTARCTICA
CLASSIFICATION
CONTINENTAL MARGIN
CORRELATIONS
EROSION
FORAMINIFERA
GEOLOGIC HISTORY
GEOLOGIC MODELS
ISOTOPE RATIO
LATITUDE EFFECT
MIOCENE EPOCH
OXYGEN 18
SEA LEVEL
ANIMALS
ANTARCTIC REGIONS
CENOZOIC ERA
EVEN-EVEN NUCLEI
GEOGRAPHICAL VARIATIONS
GEOLOGIC AGES
INVERTEBRATES
ISOTOPES
LEVELS
LIGHT NUCLEI
MICROORGANISMS
NUCLEI
OXYGEN ISOTOPES
PALEONTOLOGY
POLAR REGIONS
PROTOZOA
SARCODINA
STABLE ISOTOPES
VARIATIONS
580000* - Geosciences