Brief description
A gravity core (GC12) was collected from a depth of 990.5 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 ~175cm into the core. Four samples were collected for X-ray Diffraction (XRD) analysis; the top two, at the sediment surface (GC12-0) and at 30cm (GC12-30) represent interglacial sediment, while the lower two, at 210cm (GC12-210) and 330cm (GC12-330) represent glacial sediment. XRD analysis suggests that the majority of the carbonate is calcite during the interglacials, primarily from pelagic carbonate production. During the glacials and transitions more quartz, feldspar, aragonite and Mg calcite are present. This suggests that there is a changing dominance of pelagic, terrigenous and reef platform material within the core related to sea-level variations.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 four samples within core GC12. Two samples, at the sediment surface and at 30cm, represents interglacial sediment, while the deeper two samples, at 210cm and 330cm, represent 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 0.07 - 1.7%.
Parameters: XRD run number, 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: 28 06 2007
Data time period: 1997 to 1997
text: westlimit=151.5; southlimit=-24.5; eastlimit=153; northlimit=-23
text: uplimit=990.5; downlimit=990.5
Subjects
EARTH SCIENCE |
MARINE SEDIMENTS |
OCEAN/LAKE RECORDS |
OCEANS |
PALEOCLIMATE |
Sediment Composition |
Sediments |
amount_of_sample_components |
environment |
error |
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Other Information
(ANU_Bostock_GC12_5_data.xls)
global : 442c6f30-2501-11dc-aba4-00188b4c0af8
Identifiers
- global : 20156510-251b-11dc-aba4-00188b4c0af8
