A +20 m middle Pleistocene sea-level highstand (Bermuda and the Bahamas) due to partial collapse of Antarctic ice

Citation
Pj. Hearty et al., A +20 m middle Pleistocene sea-level highstand (Bermuda and the Bahamas) due to partial collapse of Antarctic ice, GEOLOGY, 27(4), 1999, pp. 375-378
Citations number
21
Categorie Soggetti
Earth Sciences
Journal title
GEOLOGY
ISSN journal
00917613 → ACNP
Volume
27
Issue
4
Year of publication
1999
Pages
375 - 378
Database
ISI
SICI code
0091-7613(199904)27:4<375:A+MMPS>2.0.ZU;2-O
Abstract
Marine deposits at +20 +/- 3 m on the tectonically stable coastlines of Ber muda and the Bahamas support the hypothesis of a partial collapse of the An tarctic ice sheet during the middle Pleistocene. Beach sediments fill a sea cave at +22 m in Bermuda, and horizontal, fenestrae-filled beds crop out o n platforms at two sites as high as +21 m in Eleuthera, Bahamas. Carbonate beach sands are bound by an early generation of isopachous fibrous cement t hat is characteristic of a phreatic marine environment. Amino acid racemiza tion and TIMS (thermal-ionization mass spectrometry) dates constrain the ag e of the deposits to between 390 and 550 ha, while proxy evidence supports a correlation with oxygen isotope stage 11. This direct geologic evidence o f a 20% decrease in polar ice during the middle Pleistocene has important i mplications for the stability of ice sheets during warm interglaciations.