The Ka'ena Highstand of O'ahu, Hawai'i: Further Evidence of Antarctic Ice Collapse during the Middle Pleistocene

Date
2002-01
Authors
Hearty, Paul J.
Contributor
Advisor
Department
Instructor
Depositor
Speaker
Researcher
Consultant
Interviewer
Journal Title
Journal ISSN
Volume Title
Publisher
University of Hawai'i Press
Volume
Number/Issue
Starting Page
Ending Page
Alternative Title
Abstract
Marine isotope stage (MIS) 11 may well represent one of the most significant interglacial highstand events of the past million years. Ocean volume changes charted from coastal exposures imply partial or complete melting of some of the world's major ice caps during a middle Pleistocene interglacial. The coastal geology of both Bermuda and the Bahamas yields evidence of an MIS 11 highstand 20 m higher than present. Further support for this catastrophic episode in sea-level history is revealed in subtidal and intertidal deposits at +28 ± 2 m in O'ahu, Hawai'i. The stratigraphy, petrology, and uplift history of the Hawaiian deposits strongly suggest a correlation with MIS 11, and a compilation of amino acid racemization, uranium/thorium (alpha and mass spectrometry), and electron spin resonance ages shows a scatter between 300 and 550 kyr. When corrected for uplift, the Ka'ena Highstand succession at Wai'anae Health Center (OWH1) reveals a "stepping up" of sea level through the interglaciation, similar to that described in the Bahamas. Previous studies on O'ahu attributed all 28 m elevation of the Ka'ena Highstand to uplift since 0.5 Ma, but now it appears that only 8 m of that was caused by uplift, and the remaining 20 m by eustatic sea-level rise. These findings from O'ahu strengthen evidence for the complete disintegration of the Greenland and West Antarctic ice sheets and partial melting of the East Antarctic ice sheet during the middle Pleistocene. If the instability of polar ice sheets can be linked to prolonged warm interglaciations as the data suggest, then existing conservative predictions for the magnitude of sea-level change by future "greenhouse" warming are seriously underestimated.
Description
Keywords
Citation
Hearty PJ. 2002. The Ka'ena Highstand of O'ahu, Hawai'i: further evidence of Antarctic ice collapse during the middle Pleistocene. Pac Sci 56(1): 65-81.
Extent
Format
Geographic Location
Time Period
Related To
Rights
Rights Holder
Email libraryada-l@lists.hawaii.edu if you need this content in ADA-compliant format.