Radiocarbon ages from the northern Great Barrier Reef

1978 ◽  
Vol 291 (1378) ◽  
pp. 139-158 ◽  
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Time Scale ◽  
Radiocarbon Dating ◽  
Barrier Reef ◽  
Laboratory Methods ◽  
Reef Environments ◽  
History Of ◽  
Reef Islands ◽  
Radiometric Ages

The aims of the 1973 Great Barrier Reef Expedition’s radiocarbon dating programmes were: (i) to collect live specimens from various reef environments to serve as modern reference standards; (ii) to evaluate the suitability of materials from the drilling, geomorphic and sediment programmes for dating purposes; and (iii) to date appropriate samples related to those programmes. The radiometric ages provide a time scale for the evolution of reefs and reef islands, and the history of sea level in the area. The purpose of this paper is to report results of all ages determined to date, to describe field and laboratory methods used and to assess the reliability of the ages in terms of (i) the actual materials dated and (ii) the geomorphic, ecological or stratigraphic units from which the samples were obtained. Seventy-nine determinations based on 74 samples are reported. No interpretation of the results is attempted here.

scholarly journals ANU Radiocarbon Date List VIII

Radiocarbon ◽  
1981 ◽  
Vol 23 (1) ◽  
pp. 1-13 ◽  
Author(s):  
H A Polach ◽  
R F McLean ◽  
B G Thom ◽  
D R Stoddart ◽  
David Hopley ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Time Scale ◽  
Radiocarbon Dating ◽  
Radiocarbon Date ◽  
Barrier Reef ◽  
Reef Environments ◽  
History Of ◽  
Reef Islands ◽  
Radiometric Ages

The aims of the 1973 Great Barrier Reef Expedition's radiocarbon dating programs were: 1) to collect live specimens from various reef environments to serve as modern reference standards, 2) to evaluate suitability of materials from drilling, geomorphic, and sediment programs for dating purposes, and 3) to date appropriate samples related to those programs. Radiometric ages provide a time scale for evolution of reefs and reef islands, and the history of sea level in the area.

Shelf-edge delta and reef development on a mixed siliciclastic–carbonate margin, central Great Barrier Reef

2020 ◽  
Vol 90 (10) ◽  
pp. 1286-1304
Author(s):  
James Daniell ◽  
Thomas Manoy ◽  
Robin J. Beaman ◽  
Jody M. Webster ◽  
Ángel Puga-Bernabéu
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Late Quaternary ◽  
Shelf Edge ◽  
Barrier Reef ◽  
Bathymetric Data ◽  
Impermeable Barrier ◽  
History Of ◽  
Major Impediment ◽  
Upper Slope

ABSTRACT The Great Barrier Reef (GBR) is the world's largest extant mixed silicilastic–carbonate margin. Previous research on the Great Barrier Reef has suggested that the extensive barrier reef system may act as an impermeable barrier and limit the development of delta systems during lowstands, but sufficient geophysical data to support this hypothesis are lacking. We use dense sparker seismic and sub-bottom profiler data to better understand the structure of a large lobe-shaped feature (∼ 10 km × 10 km) on the shelf edge of the central GBR and the interactions between siliciclastic and carbonate sedimentary systems. Interpreted sparker seismic contains prograding clinoforms and suggest that the lobe-shaped feature was a river-dominated shelf-edge delta. A delta on the shelf edge implies that the presence of an exposed barrier reef was not a major impediment to deposition and that other adjacent lobe-shaped features are also deltaic deposits. The shelf-edge deltas were deposited onto a broad upper-slope terrace that allowed continued progradation and limited incision when sea level fell below the shelf edge. Delta foresets are commonly colonized by coral reefs, but the spatial and temporal relationship between reefs and some deltaic units remains unclear. The presence of multiple shelf-edge deltas that link to previously mapped Burdekin River paleo-channels indicates a complex history of sedimentation, with the Burdekin River delta migrating up to 100 km along the GBR margin during the late Quaternary. Regional bathymetric data suggest that large modern or recent shelf-edge deltas are rare on the GBR and that there was a broad range of sedimentary processes operating along the margin of the GBR during periods of low sea level.

Sea level change in the Holocene on the northern Great Barrier Reef

1978 ◽  
Vol 291 (1378) ◽  
pp. 167-186 ◽  
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Radiometric Dating ◽  
Barrier Reef ◽  
Sea Levels ◽  
Level Curves ◽  
Level Change ◽  
Fossil Corals ◽  
History Of ◽  
Degree Of Confidence

Detailed studies, utilizing a range of both well controlled sea level criteria and dates, are required if Holocene time-sea level curves are to be established with any degree of confidence. This paper is restricted to an interpretation of Expedition results from the northern Great Barrier Reef, excluding those from the drill core. Extensive colonies of emergent fossil corals in growth position indicate that present sea level was first reached about 6000 a b. p. Elevations of cay surfaces, cemented rubble platforms, microatolls, coral shingle ridges, reef flats and mangrove swamps, referenced to present sea level show an array of heights. However, levels of particular features are accordant on many reefs: it is believed that these can be related to particular sea levels. Radiometric dating provides the time framework. Ages of samples from similar deposits on different reefs are surprisingly consistent. Oscillations in sea level since 6000 a b.p ., relative to present sea level, are identified with varying degrees of confidence. This history of relative sea level does not separate eustatic from noneustatic components.

scholarly journals Reef-flat and back-reef development in the Great Barrier Reef caused by rapid sea-level fall during the Last Glacial Maximum (30–17 ka)

Geology ◽  
2019 ◽  
Vol 48 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Kazuhiko Fujita ◽  
Noriko Yagioka ◽  
Choko Nakada ◽  
Hironobu Kan ◽  
Yosuke Miyairi ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Last Glacial Maximum ◽  
Reef Flat ◽  
Barrier Reef ◽  
Back Reef ◽  
Last Glacial ◽  
Reef Environments ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract Reef growth patterns and the development of associated environments have been extensively studied from reef deposits from Holocene and previous interglacial highstands. However, reefs that grew during glacial lowstands are comparatively poorly understood. Here we show the formation of reef-flat and back-reef environments following rapid sea-level fall (15–20 mm yr−1 and 20–40 m in magnitude) during the Last Glacial Maximum (LGM) on the present shelf edge of the Great Barrier Reef. Sedimentological and foraminiferal analyses of unconsolidated reef sediments recovered in cores 111–140 m below sea level at Hydrographers Passage during Integrated Ocean Drilling Project (IODP) Expedition 325 reveal the occurrence of a benthic foraminiferal assemblage dominated by the genera Calcarina and Baculogypsina, which is common in modern reef-flat and back-reef environments in the Great Barrier Reef and elsewhere. This assemblage is associated with higher foraminiferal proportions in reef sediments and higher proportions of well-preserved Baculogypsina tests in the same intervals, which also characterize reef-flat environments. Radiocarbon (14C–accelerator mass spectrometry) ages of reef-flat dwelling foraminifers (n = 22), which indicate the time when these foraminifers were alive, are consistent with the timing of the two-step sea-level fall into the LGM as defined by the previously published well-dated coralgal record. This foraminiferal evidence suggests the development of geomorphically mature fringing reefs with shallow back-reef lagoons during the LGM. Our results also imply that back-reef sediment accumulation rates during the LGM lowstand were comparable to those during the Holocene highstand.

The Great Barrier Reef and the Great Barrier Reef Expedition 1973

1978 ◽  
Vol 291 (1378) ◽  
pp. 5-22 ◽  
Keyword(s):  
Great Barrier Reef ◽  
Sea Level Change ◽  
Tree Islands ◽  
Barrier Reef ◽  
Level Change ◽  
Geophysical Surveys ◽  
History Of ◽  
Reef Islands ◽  
Modern Reef ◽  
Northern Sector

The Great Barrier Reef, the world’s longest barrier reef, extends for 2000 km along the northeast coast of Australia. It is a complex feature, with outer ribbon reefs and inner platform and patch reefs of widely differing forms. Most previous work has concentrated in the extreme south (at Heron and One Tree Islands) or in the central sector (at Low Isles). The 1973 Expedition worked in the northern sector, from Cairns to the latitude of Cape Grafton (11° 30' S). The main aim of the Expedition was to elucidate the recent history of the reefs, especially in response to Holocene sea level change. Evidence was sought from shallow coring, geophysical surveys, studies of reef and inter-reef sediments, observations on modern reef communities, and the analysis of the geology and geomorphology of reef islands. The work of the field parties in each of these areas is briefly reviewed and related to the questions to be discussed in the following papers.

Geomorphology of reef islands, northern Great Barrier Reef

1978 ◽  
Vol 284 (999) ◽  
pp. 39-61 ◽  
Keyword(s):  
Great Barrier Reef ◽  
Reef Flat ◽  
Flowering Plants ◽  
Vegetation Patterns ◽  
Barrier Reef ◽  
Large Collection ◽  
Beach Ridges ◽  
History Of ◽  
Reef Islands ◽  
Ground Nesting

During the 1973 Great Barrier Reef Expedition, 67 reef islands were mapped between latitudes 11° 30' S and 17° S on the Great Barrier Reef. During the mapping, the major topographic, lithological, sedimentological and vegetational features of the islands were distinguished, and their elevations relative to a sea level datum established. The islands themselves were categorized in terms of topographic and vegetational complexity. Previous classifications by Steers, Spender, Fairbridge and others are reviewed in the light of these findings. Some of the islands had been previously mapped by Steers in 1928-29 or 1936; on others, changes could be identified from the evidence of shoreline advance or retreat and from vegetation patterns. The floristics and vegetation units of the islands are briefly described, on the basis of the field mapping and a large collection of flowering plants. Vegetation is influenced by stage in island development, latitudinal variation in rainfall, effects of ground-nesting seabirds, and probably also by disturbance by aboriginal man. Development of mangroves on reef flats is related to stage of reef flat and island development, and relation to tidal levels. This study of the geomorphology of the islands raises questions over the nature, origin and history of specific features (ramparts, beach ridges, boulder tracts, exposed limestones) which the Expedition attempted both to define and to answer.

Phanerozoic Oxygen

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Oxygen Consumption ◽  
Organic Carbon ◽  
Sea Level ◽  
Time Scale ◽  
Atmospheric Oxygen ◽  
Sea Level Change ◽  
Oxygen Production ◽  
Level Change ◽  
History Of ◽  
Geologic Processes

This chapter discusses the modeling of the history of atmospheric oxygen. The most recently deposited sediments will also be the most prone to weathering through processes like sea-level change or uplift of the land. Thus, through rapid recycling, high rates of oxygen production through the burial of organic-rich sediments will quickly lead to high rates of oxygen consumption through the exposure of these organic-rich sediments to weathering. From a modeling perspective, rapid recycling helps to dampen oxygen changes. This is important because the fluxes of oxygen through the atmosphere during organic carbon and pyrite burial, and by weathering, are huge compared to the relatively small amounts of oxygen in the atmosphere. Thus, all of the oxygen in the present atmosphere is cycled through geologic processes of oxygen liberation (organic carbon and pyrite burial) and consumption (weathering) on a time scale of about 2 to 3 million years.

Water circulation around Britomart Reef, Great Barrier Reef, during July 1979

1980 ◽  
Vol 31 (4) ◽  
pp. 415 ◽  
Author(s):  
E Wolanski ◽  
M Jones
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Central Region ◽  
Reef Flat ◽  
Water Circulation ◽  
Barrier Reef ◽  
Trade Winds ◽  
Sea Breezes ◽  
Coral Sea ◽  
Sea Level Oscillations

Weather and currents at eight sites were measured and drogue trajectories obtained in July 1979 at Britomart Reef, a middle reef located at 18�16'S.,146� 38'E. in the central region of the Great Barrier Reef province. The longest current records (3 weeks) were obtained at two sites in passes between the Coral Sea and the Great Barrier Reef Lagoon where westerly currents modulated by tides were observed. Analysis of residuals also showed the importance of wind-driven secondary circulation. Non-tidal sea-level oscillations were very small. Shorter current records (1-10 days) at six sites in the lagoon and on the reef flat showed a predominant northerly flow, also modulated by tides and wind. A residual anticlockwise water circulation existed in the lagoon where flushing was controlled more by winds than by tides. The rise in sea level over the reef flat as a result of waves breaking was negligible. Temperature differences between air and water accounted for the cooling of the water column during the expedition. Constant south-east trade winds were experienced at the reef, while on land the wind was weaker. more variable, and often dominated by land-sea breezes.

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