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Phytoplankton Distribution in Surface Samples and Cores from Prydz Bay and Long Fjord and its Relationship to Sea Level and Climatic Change

Entry ID: ASAC_492

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Summary

Abstract: Metadata record for data from ASAC Project 492 See the link below for public details on this project.

From the abstracts of the referenced papers:

Diatom assemblages in two Holocene sediment cores (GC1 and GC2) from the Mac. Robertson Shelf, East Antarctica, are compared with modern sedimentary diatom assemblages from the same area. Open marine deposition commenced in ... Iceberg Alley (GC1), on the outer continental shelf, greater than 10.7 adj. 14C kyr BP. Chaetoceros resting spores, which may indicate water-column stabilsation from melting glacial and/or sea ice or the maximum summer sea-ice retreat, dominate the diatom assemblage. Approximately 7.5 adj. 14C kyr BP, a sea-ice diatom assemblage was deposited. This assemblage is similar to that being deposited in the surface sediments of the Mac. Robertson Shelf today and suggests that perennial sea ice has persisted in the vicinity of Iceberg Alley since that time. Interbedded within the sea-ice assemblage, however, are Corethron-rich sediment layers that suggest mid- to late-Holocene high-productivity events associated with a climatic optimum. The diatom record from Nielsen Basin (GC2), on the inner continental shelf, is relatively uniform compared to that in GC1. Glacial ice was present over the region c. greater than 5.6 adj. 14C kyr BP and a dissolution diatom assemblage was deposited beneath it. following ice retreat, an ice-edge diatom assemblage was deposited briefly before sea-ice conditions similar to that on the continental shelf today developed. There is no evidence in GC2 for the mid- to late-Holocene high-productivity events identified in GC1.

Four diatom assemblages are identified from the surface sediments of Prydz Bay and the Mac. Robertson Shelf using multivariate analysis. A coastal assemblage is characterised by the sea-ice diatoms Fragilariopsis curta, F. angulata, F. cylindrus and Pseudonitzschia turgiduloides. A continental shelf assemblage is characterised by the open-water diatoms Fragilariopsis kerguelensis, Thalassiosira lenuginosa, T. gracilis var. expecta and Trichotoxin reinboldii. The Cape Darnley assemblage contains both sea-ice and open-water diatoms, but all are characteristically large and heavily silicified. Multiple regression has been used to identify the relationships between the diatom assemblages and known environmental variables. There are strong correlations between the coastal, shelf and oceanic assemblages and ecological conditions, including latitude, sea-ice distribution and ocean currents. The Cape Darnley assemblage is thought to represent an assemblage from which the smaller and more lightly silicified species have been removed by current winnowing.

The palaeo-depositional environment of inner Prydz Bay, East Antarctica, has been reconstructed for the past 21,320 14C yr B.P., using diatom assemblages and sediment facies from a short, 352 cm long gravity core. Between 21,320 and 11,650 14C yr B.P., compact tillite and diamicton are present in the core, and diatom frustules are rare to absent. These data suggest that an ice sheet grounded over the site during the last glacial maximum. Following glacial retreat, siliceous muddy ooze was deposited, from 11,650 to 2600 14C yr B.P., in an open marine setting. During this stage, diatom frustules are abundant and well preserved, and Thalassiosira antarctica resting spores and Fragilariopsis curta dominate the assemblage. This assemblage suggests open marine deposition in an environment where the spatial and temporal distribution of sea ice is less than today. Since 2600 14C yr B.P., sea-ice and ice-edge diatom species have become more abundant, and neoglacial cooling is inferred. The assemblage is similar to that forming currently in Prydz Bay, where sea-ice is absent (less than 10% cover) for 2-3 months of the year and permanent ice edge and/or multiyear sea ice remains in close proximity to the site.

Related URL

Link: VIEW PROJECT HOME PAGE

Description: Public information for ASAC project 492

Geographic Coverage

(Click for Interactive Map)

Spatial coordinates

N: -66.8

S: -68.6

E: 76.8

W: 63.0

Temporal Coverage

Start Date: 1982-09-30

Stop Date: 1995-03-31

Paleo Temporal Coverage

Paleo Start Date: 21320 YBP
Paleo Stop Date: 11650 YBP
Chrono Unit:

PHANEROZOIC > CENOZOIC > QUATERNARY

Location Keywords

OCEAN > SOUTHERN OCEAN

CONTINENT > ANTARCTICA

GEOGRAPHIC REGION > POLAR

Science Keywords

OCEANS > MARINE SEDIMENTS

OCEANS > SEA ICE

ISO Topic Category

BIOTA

OCEANS

Quality Values provided in temporal and spatial coverage are approximate only.

Access Constraints PDF copies of the referenced papers are available for download from the provided URL.

Use Constraints This data set conforms to the PICCCBY Attribution License
(http://creativecommons.org/licenses/by/3.0/).

Please follow instructions listed in the citation reference at the provided URL when using these data.

Ancillary Keywords

CLIMATE CHANGE

DIATOMS

Data Set Progress

COMPLETE

Data Center

Australian Antarctic Data Centre, Australia

Data Center URL: http://data.aad.gov.au

Data Center Personnel
Name: DATA OFFICER AADC Phone: +61 3 6232 3244 Fax: +61 3 6232 3351 Email: metadata at aad.gov.au Contact Address: Australian Antarctic Division 203 Channel Highway City: Kingston Province or State: Tasmania Postal Code: 7050 Country: Australia

Distribution

Distribution Media: HTTP

Distribution Size: 32 MB

Distribution Format: PDF

Fees: free

Personnel

ANDREW MCMINN

Role: TECHNICAL CONTACT

Role: INVESTIGATOR

Phone: +61 3 6266 2980

Fax: +61 3 6226 2973

Email: Andrew.McMinn at utas.edu.au

Contact Address:

Institute of Antarctic and Southern Ocean Studies

University of Tasmania

Private Bag 77

City: Hobart

Province or State: Tasmania

Postal Code: 7001

Country: Australia

DAVE CONNELL

Role: DIF AUTHOR

Phone: +61 3 6232 3244

Fax: +61 3 6232 3351

Email: dave.connell at aad.gov.au

Contact Address:

Australian Antarctic Division

203 Channel Highway

City: Kingston

Province or State: Tasmania

Postal Code: 7050

Country: Australia

Publications/References

Taylor and McMinn 2001, Evidence from diatoms for Holocene climate fluctuation along the East Antarctic margin. Holocene 11(4) 455-466.

Taylor, F., and McMinn, A. 2002. Late Quaternary ? Holocene diatom assemblages from Prydz Bay, East Antarctica. Quaternary Research 57, 151-161.

Taylor, F., McMinn, A. and Franklin, D. 1997. Distribution of diatoms in surface sediments of Prydz Bay, Antarctica. Marine Micropaleontology, 32, 209-229.

Creation and Review Dates

DIF Creation Date: 2000-07-31

Last DIF Revision Date: 2010-07-26

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