Brief description
A gravity core (GC12) was collected from a depth of 990.5 mbsl within the Capricorn Channel, southern Great Barrier Reef (GBR). The 18-O values of the different foraminiferal species down the depth of the core show relatively consistent inter-species offsets throughout the glacial and interglacial periods. This provides us with confidence that the 5 individual species presumably remained within the same water mass. Because each foraminifera species fractionate carbon and oxygen isotopes differently, amended 18-O values are given whenever possible to account for these well-known biological vital effects. Comparison of the 18-O values with SPECMAP (Martinson et al., 1987) provides us with a chronology for core GC12.Lineage
Maintenance and Update Frequency: notPlanned
Statement: Samples for foraminifera picking were dried in the oven at 60oC before being re-soaked in distilled water. Samples were then wet sieved through a series of four mesh sizes before the size fractions were transferred to drying trays. After drying foraminifera were picked from under microscope for the large size fractions of >300 µm and >400µm. 10-15 individuals of each species were hand picked for isotope analysis. The samples were washed in methanol and ultrasonicated for 30 secs to remove any surface and internal particles. The samples were analysed at the Research School of Earth Science, Australian National University, using an automated individual carbonate reaction (Kiel) device coupled with a Finnigan MAT-251 mass spectrometer.
Statement: 18-O values are normalised to G. ruber for 3 of the 4 remaining foraminifera species analysed. This accounts for interspecies variability in fractionating oxygen isotopes. Amended values are not provided for Globorotalia truncatulinoides since no correction is currently available. The results for Gr. menardii and Gr. truncatulinoides are sporadic due to the absence of these species within some intervals of the core. Gr. menardii is found throughout the glacial but disappears during the early Holocene. Gr. truncatulinoides is absent during the glacial, absent during the deglaciation, and then present again in the Holocene. Values for the 3 other species (G. ruber, G. sacculifer and Cibicidoides spp.) are more regular with values typically provided every 5-10cm down to the core to a depth of 510cm.
Parameters: Depth through core (cm), age (yrs BP), foraminiferal species, oxygen-18 values down the core for different species.
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
The analysis of stable isotopes in multiple species of planktonic foraminifera provides an insight into changes in the gradients of physical and biological properties in the water column.
The analysis of stable isotopes in multiple species of planktonic foraminifera provides an insight into changes in the gradients of physical and biological properties in the water column.
Issued: 25 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
51200000 |
EARTH SCIENCE |
Foraminifera |
Foraminiferans |
Foraminiferida |
OCEAN/LAKE RECORDS |
Oxygen Isotopes |
PALEOCLIMATE |
age |
amount_of_oxygen-18_isotope_per_taxonomic_species |
core_depth |
environment |
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Other Information
(ANU_Bostock_GC12_6_data.xls)
global : 442c6f30-2501-11dc-aba4-00188b4c0af8
Identifiers
- global : 333e1c20-251d-11dc-aba4-00188b4c0af8
