Parent record: Datasets relating to core MD032607 (off South Australia)

Researchers: Spooner, Michelle (Principal investigator) ,  De Deckker, Patrick (collaborator) ,  De Deckker, Patrick, Prof (collaborator)

Brief description We must understand the natural cycles of the oceans to understand the evolution of our climate through geological time. Core MD 032607 was obtained in 2003 off the coast of Sumatra (36.9606 S, 137.4065 E). By investigating the properties and components of this core we are able to reveal some information regarding past oceanographic and climatic systems. Information obtained or inferred from the core include the isotopic composition of oxygen and carbon through time, an age vs. depth profile of the core (revealing sedimentation rates), the relative abundance of planktonic foraminifera over time, and estimates of historical sea-surface temperatures.

Lineage Maintenance and Update Frequency: notPlanned

Lineage Statement: Sample collected using a piston core. For isotope analysis carbonate tests of Globigerina bulloides were prepared, cleaned and then collected using 63mm mesh. Calculations of 13C and 18O at various depth were made by the Finnegan MAT 251 Mass Spectrometer at GEOMAR in Kiel, Germany. The chronology of the core was then deduced from oxygen isotope stratigraphy by correlating 18O values to the SPECMAP age-model. Relative abundances of planktonic foraminifera were based on counts of splits of the >150mm fractions to remove juvenile and possibly unidentifiable fragments. Each sample was split by an Otto-micro splitter until about 400 species were present in the final split. Sea-surface temperatures (SST) were estimated from planktonic foraminifera assemblage data using the modern analogue technique (MAT), in conjunction with the AUSMAT-F4 database. Each SST estimate was calculated as the mean of the best 10 analogues from the global database.

Lineage Statement: The Mass spectrometer was run concurrently with international standards NBS-19 and NBS-18, and has a very small analytical error. None of the isotope values have been amended to account for the ice-volume effect on the foraminifera during the Last Glacial Maximum (LGM). Isotope records for both 13C and 18O are complete for all of the sampling depths. From the sediment surface down to 200cm, sampling was undertaken every 5cm. From this point, down to the end of the core at 3270cm, data is not recorded for regular intervals. Data is presented for every 30-120cm of the remaining core. Given that the age vs. depth profile is based on 18O, the age has also been determined at each of the above mentioned points. In relation to relative abundance of foraminifera, individuals were accurately identified to the species level. Sea-surface temperatures (SST) were estimated from planktonic foraminifera assemblage data. This has been collected every 5cm of the core. The most precise variable of SST is mean annual temperature, followed by Tmax, then Tmin. Most of the SST estimates are reasonably precise given that the samples have good analogues in the AUSMAT-F4 database. Typically the glacial periods are less precise than the interglacials. Time periods with reduced quality of SST estimates are around 66k yrs BP and 132-144k yrs BP. Isotopic composition - parameters: Core depth (cm), oxygen-18 Ga. bulloides (parts per thousand), carbon-13 Ga. bulloides (parts per thousand). Age vs. depth - parameters: Core depth (cm), age (yrs BP). Relative abundance - parameters: Age of core (yrs BP), relative abundance of planktonic foraminifera assemblages (%). Estimated ocean temperatures - parameters: Age of core (yrs BP), mean water temperature (oC), maximum water temperature (oC), minimum water temperature (oC), depth of mixed layer (m), temperature at 50m, 100m and 150m (oC).

Notes Credit
The Australian National University (ANU)

Notes Credit
Funded by The National Oceans Office (NOO)

Notes Credit
Funded by The Australian Research Council (ARC)

Notes Credit
Funded by The French Polar Institute

Notes Credit
Funded by The Australian Institute of Nuclear Science Engineering (AINSE)

Notes Credit
Funded by The Murray Darling Basin Commission

Notes Purpose
To provide an insight into palaeoceanographic conditions in the region of the Murray Canyon system off South Australia. Also, to define the history and behaviour of the Leeuwin Current, determine past ecological conditions in the water column and to gain insight into the interactions within the water column.

Data time period: 2003-01-01 to 2003-01-01

137.41028,-36.96743 137.41148,-36.96742 137.41132,-36.9682 137.4103,-36.9682 137.41028,-36.96743

137.41088,-36.96781

137.5,-39.5 137.5,-40 137,-40 137,-39.5 137.5,-39.5

137.25,-39.75

text: westlimit=137; southlimit=-40; eastlimit=137.5; northlimit=-39.5

text: uplimit=865; downlimit=865