Submerged relict reefs and modern coral colonisation discovered beyond the threshold of modern reef growth: Balls Pyramid platform, southwest Pacific Ocean  


Authors / CoAuthors

Linklater, M. | Woodroffe, C.D. | Brooke, B. | Nichol, S.L.

Abstract

Submerged relict reef systems and modern coral communities discovered around the Balls Pyramid shelf are presented as new evidence of extensive carbonate production at the boundary of reef-forming seas. Balls Pyramid is the southernmost island in a chain of island-reefs in the southwest Pacific Ocean, 24 km south of the southernmost known coral reef in the Pacific Ocean at Lord Howe Island. This paper explores the detailed geomorphic structure of the shelf through the production of a high resolution bathymetric model from multibeam echosounder data and depth estimates from satellite imagery. Key seafloor features identified include a large, mid shelf reef dominating the shelf landscape in 20 - 60 m water depth, mid shelf basins and channels, and shelf margin terrace sequences in 50 - 100 m depth. Sub-bottom profiles, backscatter, drill core and vibro-core data are used to investigate the seafloor composition. Drill cores extracted from the submerged reef surface confirm coral, coralline algae and cemented sands composition, and vibro-core material extracted from unconsolidated areas demonstrate substantial accumulation of carbonates shed from the reef surface. Underwater video imagery reveals abundant modern mesophotic reef communities, including hard corals, colonising the relict reef surface. This paper reveals prolific past reef growth and abundant modern coral growth on what was previously considered to be a planated volcanic shelf outside of reef-forming seas, thus extending understanding of reef evolution at, and beyond, the limits of growth.

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nonGeographicDataset

eCat Id

82202

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EGD  

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Commonwealth of Australia (Geoscience Australia)  
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Australia

Keywords

  • External PublicationScientific Journal Paper
( Theme )
  • marine biodiversity
( Theme )
  • NERP Marine Biodiversity Hub
( Theme )
  • bathymetry
( Theme )
  • continental shelf
( Theme )
  • marine
  • NSW
Australian and New Zealand Standard Research Classification (ANZSRC)
  • Earth Sciences
  • Published_Internal

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2014-09-15T00:00:00

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geoscientificInformation

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