Authors / CoAuthors
Heap, A.D. | Dickens, G.R. | Stewart, L.K.
Abstract
Nara Inlet in the Whitsunday Islands is a natural depocenter for clastic and carbonate sediment on the middle shelf of the central Great Barrier Reef (GBR) platform. Three sediment cores were collected from the inlet to understand sediment accumulation in this tropical mixed clastic/carbonate system over time. Surface and subsurface sediment is comprised of two main components: terrigenous clay and shallow marine carbonate. Similar to other regions on the middle shelf of the GBR platform, the carbonate component, 25.80% by weight and dominated by Sr-poor foraminifera tests and mollusc shells, generally increases towards the surface. Radiocarbon ages derived from tests of benthic foraminifera indicate that the top 3 m of sediment accumulated within the last 3000 years, but that the rate has slowed toward present-day. The change in clastic and carbonate abundance therefore indicates a system where both clastic and carbonate accumulation has decreased over time, but where clastic accumulation has decreased faster. Reduced clastic accumulation may reflect progressive impedance of terrigenous input by a laterally growing fringing reef at the mouth of Nara Inlet. Likewise, reduced carbonate accumulation may reflect preferential reef growth and carbonate deposition outside of the inlet. Even though clastic accumulation has decreased significantly over time, the late Holocene mass, composition, and distribution of clastic material in Nara Inlet implies a terrigenous source previously unrecognized in models for the evolution of the GBR platform. Large amounts of terrigenous sediment probably were stored around topographic highs on the middle shelf during lowstand and early transgression. This clastic material was then removed over time, mixed with autochthonous carbonate, and deposited in embayments on the middle shelf. The accumulation of sediment on the middle shelf of a tropical mixed clastic/carbonate margin is not straightforward.
Product Type
nonGeographicDataset
eCat Id
61439
Contact for the resource
Custodian
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Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Digital Object Identifier
Keywords
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- External PublicationScientific Journal Paper
- ( Theme )
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- marine
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- AU-QLD
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
2001-01-01T00:00:00
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unknown
Topic Category
geoscientificInformation
Series Information
176
Lineage
Unknown
Parent Information
Extents
[-22.0, -18.0, 147.0, 150.0]
Reference System
Spatial Resolution
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Associations
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Source data not available.