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Holocene sea level instability in the southern Great Barrier Reef, Australia: high-precision U¿Th dating of fossil microatolls

Journal Article


Abstract


  • Three emergent subfossil reef flats from the inshore Keppel Islands, Great Barrier Reef (GBR), Australia, were used to reconstruct relative sea level (RSL). Forty-two high-precision uranium–thorium (U–Th) dates obtained from coral microatolls and coral colonies (2σ age errors from ±8 to 37 yr) in conjunction with elevation surveys provide evidence in support of a nonlinear RSL regression throughout the Holocene. RSL was as least 0.75 m above present from ~6500 to 5500 yr before present (yr BP; where “present” is 1950). Following this highstand, two sites indicated a coeval lowering of RSL of at least 0.4 m from 5500 to 5300 yr BP which was maintained for ~200 yr. After the lowstand, RSL returned to higher levels before a 2000-yr hiatus in reef flat corals after 4600 yr BP at all three sites. A second possible RSL lowering event of ~0.3 m from ~2800 to 1600 yr BP was detected before RSL stabilised ~0.2 m above present levels by 900 yr BP. While the mechanism of the RSL instability is still uncertain, the alignment with previously reported RSL oscillations, rapid global climate changes and mid-Holocene reef “turn-off” on the GBR are discussed.

Publication Date


  • 2016

Citation


  • Leonard, N. D., Zhao, J. X., Welsh, K. J., Feng, Y. X., Smithers, S. G., Pandolfi, J. M., & Clark, T. R. (2016). Holocene sea level instability in the southern Great Barrier Reef, Australia: high-precision U¿Th dating of fossil microatolls. Coral Reefs, 35(2), 625-639. doi:10.1007/s00338-015-1384-x

Scopus Eid


  • 2-s2.0-84949808669

Start Page


  • 625

End Page


  • 639

Volume


  • 35

Issue


  • 2

Abstract


  • Three emergent subfossil reef flats from the inshore Keppel Islands, Great Barrier Reef (GBR), Australia, were used to reconstruct relative sea level (RSL). Forty-two high-precision uranium–thorium (U–Th) dates obtained from coral microatolls and coral colonies (2σ age errors from ±8 to 37 yr) in conjunction with elevation surveys provide evidence in support of a nonlinear RSL regression throughout the Holocene. RSL was as least 0.75 m above present from ~6500 to 5500 yr before present (yr BP; where “present” is 1950). Following this highstand, two sites indicated a coeval lowering of RSL of at least 0.4 m from 5500 to 5300 yr BP which was maintained for ~200 yr. After the lowstand, RSL returned to higher levels before a 2000-yr hiatus in reef flat corals after 4600 yr BP at all three sites. A second possible RSL lowering event of ~0.3 m from ~2800 to 1600 yr BP was detected before RSL stabilised ~0.2 m above present levels by 900 yr BP. While the mechanism of the RSL instability is still uncertain, the alignment with previously reported RSL oscillations, rapid global climate changes and mid-Holocene reef “turn-off” on the GBR are discussed.

Publication Date


  • 2016

Citation


  • Leonard, N. D., Zhao, J. X., Welsh, K. J., Feng, Y. X., Smithers, S. G., Pandolfi, J. M., & Clark, T. R. (2016). Holocene sea level instability in the southern Great Barrier Reef, Australia: high-precision U¿Th dating of fossil microatolls. Coral Reefs, 35(2), 625-639. doi:10.1007/s00338-015-1384-x

Scopus Eid


  • 2-s2.0-84949808669

Start Page


  • 625

End Page


  • 639

Volume


  • 35

Issue


  • 2