Mechanisms of spur and groove development and implications for reef platform evolution

Duce, Stephanie, Dechnik, Belinda, Webster, Jody M., Hua, Quan, Sadler, James, Webb, Gregory E., Nothdurft, Luke, Salas-Saavedra, Marcos, and Vila-Concejo, Ana (2020) Mechanisms of spur and groove development and implications for reef platform evolution. Quaternary Science Reviews, 231. 106155.

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Abstract

Contemporary understanding of Holocene coral reef development is based primarily on sub-surface investigations of reef flat, back reef and lagoon zones. Few studies of Holocene fore reef development exist, constituting a significant gap in our understanding of reef evolution. The spur and groove (SaG) zone is a distinct, understudied, feature of fore reefs worldwide. We review SaG development from previous studies and present 29 new SaG short cores with 52 ¹⁴C and U-Th ages from six fore reef regions of Heron and One Tree reefs, the first such data from the Great Barrier Reef. Remarkably, we found that SaGs do not necessarily accrete in the same direction as their adjacent reef flat. We identified three modes of reef flat and SaG lateral accretion: Mode 1 - lagoonward accretion of both the reef flat and SaGs; Mode 2 - lagoonward accretion of the reef flat but seaward accretion of the SaGs; Mode 3 - seaward accretion of both the reef flat and SaGs. Most SaG zones (five of the six studied) accreted in a seaward direction (Modes 2 or 3). Hydrodynamic conditions and local topography appear to be the dominant factors determining which mode occurs. Episodic high-energy events are also likely to play an important role in SaG formation. Our findings suggest that traditionally held models of reef evolution whereby lagoonal, mature reefs fill, developing into senile platform reefs, may not hold. Rather, reef flats may continue to expand seaward on their leeward, and semi-exposed fronts to increase in size while maintaining their lagoons.

Item ID: 62707
Item Type: Article (Research - C1)
ISSN: 1873-457X
Keywords: reef growth, coral reef geomorphology, spur and groove, accretion, holocene, great barrier reef
Copyright Information: © 2019 Published by Elsevier Ltd.
Funders: Australian Institute of Nuclear Science and Engineering (AINSE), University of Sydney (US), Australian Research Council (ARC), One Tree Island Research Station (OTIRS), Australian Coral Reef Society (ACRS), Heron Island Research Scholarship
Projects and Grants: AINSE Postgraduate Award ALNSTU11922, ARC DiscoveryProject DP120101793, OTIRS Student Fellowship, ACRS Danielle Simmons Student Research Award, ARC Future Fellowship FT100100215, US Women in Science return to work grant
Date Deposited: 08 Apr 2020 07:33
FoR Codes: 04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040606 Quaternary Environments @ 50%
04 EARTH SCIENCES > 0403 Geology > 040305 Marine Geoscience @ 50%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 30%
97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 70%
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