Brief description
A gravity core (GC14) was collected from a depth of 2004 mbsl within the Capricorn Channel, southern Great Barrier Reef (GBR). Analysis of other parameters revealed the Last Glacial Maximum (LGM) sitting at a depth of ~80cm into the core. Two samples were collected for X-ray Diffraction (XRD) analysis; from the sediment surface (GC14-0) representing interglacial sediment, while the second sample, from 80cm (GC14-80) represents glacial sediment. XRD analysis of these samples show a slight increase in carbonate percentage during the interglacial compared to the glacial, with increased clay and quartz during the glacial. During the interglacial there are minor amounts of Mg calcite, which suggests that there is little influence from the reef platform on the sediments during the present sea-level, or that the core is presently below the Mg calcite compensation depth.Lineage
Maintenance and Update Frequency: notPlanned
Statement: For X-Ray Diffraction (XRD) analysis samples were ground in an agate mortar with acetone or ethanol, then dried, and filled into side-packed sample holders. Powder diffraction data was collected at room temperature with a Siemens D501 diffractometer at the Department of Earth and Marine Science, The Australian National University. The diffractometer was equipped with a curved graphite monochromator, a scintillation detector, and CuK alpha radiation was used. Scans were recorded in one pass from 2 to 70 degrees 2-theta, using a step-width of 0.02 degrees and a scan speed of 1 degree per minute. The results were interpreted using the SIEMENS software package Diffracplus Eva (2000), and quantitative estimates were performed using the program Siroquant 2.5.
Statement: XRD analysis was undertaken for two samples within core GC14. The first, at the sediment surface represents interglacial sediment, while the second sample at 80cm, represents glacial sediments. Clay data must be treated with caution since it has been suggested that clay minerals, transported to the coast by river suspended loads, undergo significant diagenesis within environments like mangroves. The percentages of sample components are not exact and the dataset also displays the % error of each component. Errors range from 0.06 - 0.76%.
Parameters: XRD run number, sample code and depth (cm), percentage of sample components (%), total percentage (%).
Notes
CreditFunded by The Australian Research Council (ARC)
Credit
Funded by The Australian National University (ANU) Faculties Research Grant Scheme
Funded by The Australian National University (ANU) Faculties Research Grant Scheme
Purpose
To help determine changes in the carbonate mineralogy and terrestrial influx, which may provide some useful palaeoclimate information. Very little previous work has been undertaken within this area.
To help determine changes in the carbonate mineralogy and terrestrial influx, which may provide some useful palaeoclimate information. Very little previous work has been undertaken within this area.
Issued: 04 07 2007
Data time period: 1997 to 1997
text: westlimit=154; southlimit=-24; eastlimit=154.5; northlimit=-23.5
text: uplimit=2004; downlimit=2004
Subjects
EARTH SCIENCE |
MARINE SEDIMENTS |
OCEAN/LAKE RECORDS |
OCEANS |
PALEOCLIMATE |
Sediment Composition |
Sediments |
amount_of_sample_components |
core_depth |
environment |
error |
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Other Information
(ANU_Bostock_GC14_5_data.xls)
global : 13f86210-29ca-11dc-b961-00188b4c0af8
Identifiers
- global : b5948500-29d3-11dc-b961-00188b4c0af8
