Geomorphic evidence of major sea-level fluctuations during marine isotope substage-5e, Cape Cuvier, Western Australia

O'Leary, M.J., Hearty, P.J., and McCulloch, M.T. (2008) Geomorphic evidence of major sea-level fluctuations during marine isotope substage-5e, Cape Cuvier, Western Australia. Geomorphology, 102 (3-4). pp. 595-602.

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Abstract

A detailed geomorphologic and morphostratigraphic investigation of raised marine terraces at Cape Cuvier, Western Australia, reveals two morphologically distinct units. A lower, well-developed accretional reef terrace between 3 and 5.5 m above MLWS (mean low-water springs; hereafter denoted as "+") represents an extended interval of stable sea level. An upper erosional terrace and incipient coralgal rim between + 8.5 to 10.5 m represents a brief sea-level stillstand at this higher elevation. These features suggest the lower and upper terraces developed during discrete sea-level events. In an attempt to better define the timing of emplacement of each marine unit, 20 coral samples collected along vertical and lateral reef growth axis from both terraces were analysed with U-series dating. Unfortunately, all coral samples exhibited elevated δ234Uinitial values, suggesting that pervasive uptake of 234U-enriched uranium and 230Th thorium had occurred. Despite the shortcomings of absolute dating, a succession of events can be resolved though morphostratigraphic relationships. Comparison of the facies relationships, coral growth, and morphostratigraphic features between the lower and upper terraces indicates that an early to mid MIS 5e stillstand at + 3 to 5 m was followed by a late rise to + 8.5 to 10.5 m. This agrees with an emerging global view of MIS 5e sea-level history derived from stable carbonate platforms, rejecting the hypothesis that these higher sea-level benchmarks are an artefact of localized tectonic processes.

Item ID: 24324
Item Type: Article (Research - C1)
ISSN: 1872-695X
Keywords: sea-level changes; coral reefs; marine terraces; U-series; MIS 5e; Cape Cuvier
Date Deposited: 20 Dec 2012 05:09
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040310 Sedimentology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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