Researchers: Ryan, David (Principal investigator) , Opdyke, Bradley, Dr (collaborator)
Brief description Wistari Reef is a lagoonal platform reef, situated on the Tropic of Capricorn, within the Capricorn and Bunker region of the southern Great Barrier Reef. Fives cores were collected and analysed for 14C radiocarbon dating, sedimentation rates and granulometry data. The effects of bioturbation within the cores was pronounced, and as such ages were likely to be undersestimated for deeper samples, and overestimated for shallower samples. From the results, the oldest age estimate obtained was from the base of core VC-01 and was aged at 2150±70 yr BP. All core tops were estimated to be ~1100±70 yr BP. The biggest maximum rate of accretion was seen at core IC-02, which exhibited an accretion rate of 4.79m/ka. The smallest minimum accretion rate was seen in VC-02 (on a sanded reef flat) with a accretion rate of 0.57m/ka.
Lineage Statement: RADIOCARBON DATING AND SEDIMENTATION RATES - Core IC-01 and IC-02 was collected using an impact core, while cores VC-01, VC-02 and VC-03 were collected using a vibrocore. Core samples were sealed in plastic (impact cores) and aluminium (vibracores) for transport, and stored in a constant temperature cool room until analysis. Impact core was split using a small vibrating saw, and cut lengthways where possible. Vibracores opened using a small angle grinder, and split in a similar manner. Cores logged and samples collected from top and base. Samples were collected from the centre of each split core, in order to avoid contamination. Approximately 30g of sediment was taken for each sample, and each was spread onto plastic dish and air dried for 24 hrs. GRANULOMETRY DATA - Sediment samples were sieved in order to determine modal particle diameters, and sorting data. A stack of US standard square mesh sieves was employed, following methods outlined by Folk (1961). Samples were first dry sieved. Sieves of sizes -1.0(phi) to 2.5(phi) were stacked and installed on a sieving shaker. Samples were weighed out to approximately 250g, and each sample was sieved for 15 minutes to ensure correct separation of fractions. Each fraction was then removed, and weighed. The size fractions 2.5phi, 3.0phi, 3.5phi and 4.0phi were pre-weighed, and wet sieved separetely using a low pressure water hose, through smaller micropalaeontological sieves.
Lineage Statement: RADIOCARBON DATING - Core VC-01 was radiometrically dated only at the core base. The three other cores (IC-02, VC-02 and VC-03) were age determined both at the core top, and at the core base. Core IC-01 was not subjected to radiocarbon dating. The effects of bioturbation within the cores was pronounced, and as such ages are likely to be undersestimated for deeper samples, and overestimated for shallower samples. Parameters: Core, latitude (decimal degrees), longitude (decimal degrees), core length (cm), core top (cm), age (yBP), core base (cm), age (yBP). SEDIMENTATION RATES - The maximum sedimentation rate represents the accumulation that has occurred between the core top date and the core base date; the minimum accretion rate takes only the basal core data into account , thus allowing for bioturbation of the sediments. Maximum and minimum accretion rates are presented for two of the cores, IC-02 and VC-02. For core VC-01, the data only shows the maximum accretion rate, while for core VC-03 only the minimum accretion rate is calculated. Parameters: Core, latitude (decimal degrees), longitude (decimal degrees), zone, maximum accretion rate (m/ka), minimum accretion rate (m/ka). GRANULOMETRY DATA - The histograms show the distribution of grainsize for the four sampled cores (IC-01, IC-02, VC-02 and VC-03). Each core has been sampled three times, once at the core top, once at the core base and once in the middle. No granulometry data exists so core VC-01. Parameters: Core, latitude (d,m,s), longitude (d,m,s), grainsize (phi), description of cores (text).
Notes
Credit
Funded by The Australian Research Council (ARC)
Notes
Credit
The Australian National University (ANU)
Notes
Purpose
To provide information on the sedimentary zones of Wistari Reef. Conducted as part of a broader study looking at Holocene production and accumulation of sediments on Wistari Reef.
Data time period: 1998 to 1998
text: westlimit=151.5; southlimit=-24.5; eastlimit=153; northlimit=-23
text: uplimit=137.5; downlimit=0
Sediment data - Wistari Reef (aodn:sediment_data_wistari_reef)
- global : c30fa590-0e74-11dc-8c12-00188b4c0af8