AMINOSTRATIGRAPHY AND AGES OF PLEISTOCENE LIMESTONES OF BERMUDA

Citation
Pj. Hearty et al., AMINOSTRATIGRAPHY AND AGES OF PLEISTOCENE LIMESTONES OF BERMUDA, Geological Society of America bulletin, 104(4), 1992, pp. 471-480
Citations number
42
Language
INGLESE
art.tipo
Article
ISSN journal
0016-7606
Volume
104
Issue
4
Year of publication
1992
Pages
471 - 480
Database
ISI
SICI code
0016-7606(1992)104:4<471:AAAOPL>2.0.ZU;2-P
Abstract
The Pleistocene stratigraphy of Bermuda offers important information f or sea-level history. Corals are rare in Bermuda Pleistocene carbonate s, and so many deposits are not appropriate for U-series dating. We ha ve extended the geochronological base in Bermuda by determining the ex tent of isoleucine epimerization (A/I ratios) in (1) marine shells (Gl ycymeris and others) from deposits of sea-level high stands, (2) land snails (Poecilozonites) from protosols associated with the eolianites that comprise the bulk of Bermuda, and (3) whole-rock samples of biocl astic calcarenites. The three distinct types of samples provide indepe ndent aminostratigraphies (Aminozones C, E, F, G, H, J, and K) that ar e mutually consistent and in agreement with the mapped lithostratigrap hy. Correlation of the amino acid ratios with ages based on previously published U-series coral dates verifies the utility of the apparent p arabolic kinetics model for estimation of amino acid racemization ages . Extrapolation of ages based on the model to deposits beyond the rang e of U-series dating reveals that a significant middle Pleistocene sec tion is present in Bermuda.