Early Oligocene ice-sheet expansion on Antarctica; stable isotope and sedimentological evidence from Kerguelen Plateau, southern Indian Ocean

Online Access: Get full text
doi: 10.1130/0091-7613(1992)020<0569:EOISEO>2.3.CO;2
Author(s): Zachos, James C.; Breza, James R.; Wise, Sherwood W.
Author Affiliation(s): Primary:
Univ. Mich., Dep. Geol. Sci., Ann Arbor, MI, United States
Fla. State Univ., United States
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 20(6), p.569-573. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. 34 refs.; illus. incl. sketch map
Summary: Sedimentological and stable isotope data from a pelagic sequence recovered from the southern Indian Ocean provide the most convincing evidence to date for short-term expansion of a large ice sheet on Antarctica during the earliest Oligocene (∼36 Ma). Terrigenous debris identified as ice-rafted in origin on the basis of textural, compositional, and size criteria is present at the same stratigraphic level as the ubiquitous early Oligocene oxygen isotope shift. The highest benthic foraminiferal δ18O values (>3.0ppm) of the Paleogene occur in samples from within the ice-rafted debris interval. These values are similar to those recorded by Holocene benthic foraminifera, implying that the ice sheet may have attained a volume similar to that of the present-day ice sheet on Antarctica. The stratigraphic distribution of ice-rafted debris and high oxygen isotope values indicate that these conditions persisted for roughly 100 ka.
Year of Publication: 1992
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Antarctica; C-13/C-12; Carbon; Cenozoic; Depositional environment; Diatoms; Foraminifera; Glacial environment; Glacial geology; Glaciation; Glaciomarine environment; Ice movement; Ice rafting; Ice sheets; Indian Ocean; Indian Ocean Islands; Invertebrata; Isotopes; Kerguelen Islands; Kerguelen Plateau; Leg 120; Lower Oligocene; Marine environment; Marine sediments; Microfossils; Nannofossils; O-18/O-16; ODP Site 748; Ocean Drilling Program; Oligocene; Oxygen; Paleo-oceanography; Paleoclimatology; Paleogene; Pelagic sedimentation; Plantae; Protista; Radiolaria; SEM data; Sedimentation; Sediments; Southern Indian Ocean; Stable isotopes; Stratigraphy; Tertiary; Thallophytes; Transport
Coordinates: S582000 S581000 E0785900 E0785830
Record ID: 1992034412
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.