Coral reef evolution on rapidly subsiding margins

Webster, Jody M., Braga, Juan Carlos, Clague, David A., Gallup, C.D., Hein, James R., Potts, Donald, Renema, Willem, Riding, Robert, Riker-Coleman, K.E., Silver, Eli, and Wallace, Laura M. (2009) Coral reef evolution on rapidly subsiding margins. Global and Planetary Change, 66 (1-2). pp. 129-148.

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Abstract

A series of well-developed submerged coral reefs are preserved in the Huon Gulf (Papua New Guinea) and around Hawaii. Despite different tectonics settings, both regions have experienced rapid subsidence (2–6 m/ka) over the last 500 ka. Rapid subsidence, combined with eustatic sea-level changes, is responsible for repeated drowning and backstepping of coral reefs over this period. Because we can place quantitative constraints on these systems (i.e., reef drowning age, eustatic sea-level changes, subsidence rates, accretion rates, basement substrates, and paleobathymetry), these areas represent unique natural laboratories for exploring the roles of tectonics, reef accretion, and eustatic sea-level changes in controlling the evolution of individual reefs, as well as backstepping of the entire system. A review of new and existing bathymetric, radiometric, sedimentary facies and numerical modeling data indicate that these reefs have had long, complex growth histories and that they are highly sensitive, recording drowning not only during major deglaciations, but also during high-frequency, small-amplitude interstadial and deglacial meltwater pulse events. Analysis of five generalized sedimentary facies shows that reef drowning is characterized by a distinct biological and sedimentary sequence. Observational and numerical modeling data indicate that on precessional (20 ka) and sub-orbital timescales, the rate and amplitude of eustatic sea-level changes are critical in controlling initiation, growth, drowning or sub-aerial exposure, subsequent re-initiation, and final drowning. However, over longer timescales (> 100–500 ka) continued tectonic subsidence and basement substrate morphology influence broad scale reef morphology and backstepping geometries. Drilling of these reefs will yield greatly expanded stratigraphic sections compared with similar reefs on slowly subsiding, stable and uplifting margins, and thus they represent a unique archive of sea-level and climate changes, as well as a record of the response of coral reefs to these changes over the last six glacial cycles.

Item ID: 5576
Item Type: Article (Refereed Research - C1)
Keywords: carbonate platforms; coral reefs; drowning; sedimentary facies; Pleistocene sea-level change; meltwater pulse events; Hawaii; Papua New Guinea
ISSN: 1872-6364
Date Deposited: 17 Nov 2009 23:18
FoR Codes: 04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040606 Quaternary Environments @ 100%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960309 Effects of Climate Change and Variability on the South Pacific (excl. Australia and New Zealand) (excl. Social Impacts) @ 50%
97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 50%
Citation Count from Web of Science Web of Science 17
Downloads: Total: 1
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