Coral growth rate and subsidence controls on the variability of coral reef profile forms
Abstract
The elevation profiles of coral reefs exhibit a range of characteristic morphologies, including uplifted terraces, platforms, barrier reefs enclosing a lagoon, and drowned reefs. This observed variety of reef forms contrasts with the canonical model in which coral reefs progress along an evolutionary path from fringing to barrier reef then to atoll as an ocean island ages, erodes and subsides. Previous efforts to model coral reef development have related reef morphology to these forcings, but none have systematically explored reef evolution over the expansive range of conditions that different islands are likely to have experienced in the recent geologic past. Thus, despite more than a century of research, the mechanisms responsible for the variability in Pleistocene reef morphology remain unclear. We present a model of reef profile evolution that incorporates simple functions of coral growth and wave erosion, and is driven by island vertical motion (subsidence or uplift) and a sea level record for the past 400 kyr. We find that eight distinct reef types emerge at different combinations of vertical motion rate and coral growth rate. Comparing modeled reef elevation profiles with those of natural reefs on islands spanning a range of vertical motion and coral growth rates, we find good agreement between the observed and modeled reef types. Using different sea-level scenarios, the model also shows that the frequency and magnitude of sea level oscillations play a key role in the development of reef morphology. These results build on our understanding of how coral reefs have developed and evolved over the Pleistocene, also providing a framework to understand how future sea level changes may impact coral reefs.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMEP51B0851T
- Keywords:
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- 1824 HYDROLOGY / Geomorphology: general