Holocene sea level instability in the southern Great Barrier Reef, Australia: high-precision U–Th dating of fossil microatolls
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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.
KeywordsSea level Holocene Great Barrier Reef Microatoll Uranium–thorium Reef hiatus
We thank C. Murray-Wallace and one anonymous reviewer for their comments which improved this manuscript. Also Hannah Markham, Mauro Lepore, Martina Prazeres, Ian Butler and others involved in fieldwork, the crew of MV Adori, and A.D. Nguyen. This study was funded by the National Environmental Research Programme Tropical Ecosystems Hub Project 1.3 to J-xZ, JMP, SGS, TRC, Y-xF and others, Australian Research Council Linkage, Infrastructure, Equipment and Facilities (LIEF) grant (LE0989067 for the MC-ICP-MS) to J-xZ, JMP, Y-xF and others, and an Australian Postgraduate Award to NDL. Samples were collected under permit G12/34,979.1.
- Brooke B, Ryan D, Pietsch T, Olley J, Douglas G, Packett R, Radke L, Flood P (2008) Influence of climate fluctuations and changes in catchment land use on late Holocene and modern beach-ridge sedimentation on a tropical macrotidal coast: Keppel Bay, Queensland, Australia. Mar Geol 251:195–208CrossRefGoogle Scholar
- Buddemeier RW, Hopley D (1988) Turn-ons and turn-offs: causes and mechanisms of the initiation and termination of coral reef growth. Proc 6th Int Coral Reef Symp 1:253–261Google Scholar
- Bureau of Meteorology (2011) Australian climate variability and change — time series graphs. Australian Bureau of Meteorology, Commonwealth of Australia. http://www.bom.gov.au/climate
- Church JA, Clark PU, Cazenave A, Gregory JM, Jevrejeva S, Levermann A, Merrifield MA, Milne GA, Nerem RS, Nunn PD, Payne AJ, Pfeffer WT, Stammer D, Unnikrishnan AS (2013) Sea level change. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate change 2013: the physical science basis. Contribution of working group I to the fifth assessment report of the Intergovernmental Panel on Climate Change, Cambridge, UK and New York, NY, USA, pp 1137–1186Google Scholar
- Kleypas JA, Hopley D (1992) Reef development across a broad continental shelf, southern Great Barrier Reef, Australia. Proc 7th Int Coral Reefs Symp 2:1129–1141Google Scholar
- Ludwig KR (2003) Isoplot/Ex, version 3: a geochronological toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publications, Berkeley, CA, USAGoogle Scholar
- Neumann AC, Macintyre IG (1985) Reef response to sea level rise: keep-up, catch up or give-up. Proc 5th Int Coral Reef Symp 3:105–110Google Scholar
- Nunn PD (1998) Sea-level changes over the past 1,000 years in the Pacific. J Coast Res 14:23–30Google Scholar
- Pirazzoli PA, Pluet J (1991) World atlas of Holocene sea-level changes. Elsevier, Amsterdam, New YorkGoogle Scholar
- Shen C-C, Fan T-Y, Meltzner AJ, Taylor FW, Quinn TM, Chiang H-W, Kilbourne KH, Li K-S, Sieh K, Natawidjaja D, Cheng H, Wang X, Edwards RL, Lam DD, Hsieh Y-T (2008) Variation of initial 230Th/ 232Th and limits of high precision U-Th dating of shallow-water corals. Geochim Cosmochim Acta 72:4201–4223CrossRefGoogle Scholar
- Yu K, Hua Q, Zhao J-x, Hodge E, Fink D, Barbetti M (2010) Holocene marine 14C reservoir age variability: evidence from 230Th-dated corals in the South China Sea. Paleoceanography 25 (doi: 10.1029/2009PA001831)