Rates of Quaternary Ice Movement Across the Vestfold Hills from Exposure Age Dating.

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Identification_Information:

Citation:

Citation_Information:

Originator: Unknown

Publication_Date: Unknown

Title: Rates of Quaternary Ice Movement Across the Vestfold Hills from Exposure Age Dating.

Description:

Abstract:

The data set consist of in-situ cosmogenic Be-10 and Al-26 surface exposure ages for subglacial erratics in the Vestfold Hills. Samples were collected during the 1994/95 summer season and processed at the research School of Earth Sciences, ANU. Al-26/Al-27 and Be-10/Be-9 ratios were measured using the 14UD acellerator mass spectrometer at the Research School of Physical Sciences and Engineering, ANU. Background information: The Earth is continually being bombarded by high-energy cosmic rays that originate predominantly from super nova explosions within our galaxy. Interactions between these high energy cosmic rays and the Earth's atmosphere creates secondary cosmic rays, including neutrons and muons. When reaching the Earth's surface these high energy particles can penetrate meters into rock and sediment. Nuclear interactions between neutrons and muons and minerals such as quartz, calcite, K-feldspar, and olivine, produce long-lived terrestrial cosmogenic nuclides (TCNs) such as Be-10, Al-26 and Cl-36. The production rates of these TCNs are almost unimaginably small - a few atoms per gram of rock per year, however using accelerator mass spectrometry (AMS) we can detect and count the cosmogenic isotopes down to levels of a few thousand atoms per gram (parts per billion of parts per billion!). The build-up of cosmogenic isotopes through time provides us with a way to measure the length of time since a rock surface became exposed to cosmic radiation. For example, the Vestfold Hills were buried under the East Antarctic ice sheet and shielded from cosmic rays by the ice. But when the ice margin retreated the Vestfold Hills became exposed to cosmic rays and TCNs began to accumulate in quartz crystals of glacial erratics left behind by the retreating ice. By measuring the Be-10 and Al-26 concentration in these erratics it has been possible to determine when the last ice retreat took place. Apart from providing a history of ice retreat across the Vestfold Hills, this study also highlighted the need for very careful sample selection. The production of TCNs in a rock surface decreases roughly exponentially with depth, with very little production occurring below about 2 meters. If a surface has been exposed to cosmic rays and is subsequently covered by ice that erodes 2 or more meters of rock from the surface the accumulated TCNs would be removed. However, if the ice does not erode 2 or more meters of rock than the surface has an inherited TCN concentration after the ice retreats. Striated bedrock surfaces are often considered as classic indicators of how erosive ice is. However, unpublished data from striated bedrock surfaces in the Vestfold Hills yielded much older ages than the deglaciation ages obtained from erratics, indicating that glacial erosion of the bedrock sites was not sufficient to remove the cosmogenic nuclide inventory inherited from prior exposure periods. This cosmogenic nuclide inheritance does however indicate that the sampled bedrock surfaces had previously been exposed to cosmic rays, i.e. the continental ice margin has repeatedly advanced and retreated across the Vestfold Hills. Importantly, if the aim is to obtain deglaciation ages from glacial landscapes or deposits, every effort should be made to sample glacial erratics rather than striated bedrock. Astract from the referenced paper: Cosmogenic nuclide measurements on two subglacially derived erratics from the Vestfold Hills, East Antarctica indicate retreat of the continental ice margin from a position at least 5 km west of its present location around 12-9 ka. These ages are similar to C-14 dates on the oldest organic sediment in lakes around the Hills, suggesting that biological colonization of lake basins coincided with glacial retreat. Whether this indicates recession of ice that extended across the entire Vestfold Hills, or an amelioration of climate that simply thawed lakes and melted a much less extensive ice cover cannot be established from the results so far. recession appears to have continued recently, with results from a third sample indicating emergence of a small nunatak, Ultima Bluff, within the past 2 ka. The fields in this dataset are: Sample Latitude Longitude Altitude Thickness Beryllium Aluminium Exposure Age

Purpose:

Not Available

Supplemental_Information:

REFERENCE: Fabel, D., J. Stone, L.K. Fifield and R.G. Cresswell, 1997. Deglaciation of the Vestfold hills, East Antarctica: Preliminary Evidence from Exposure Dating of Three Subglacial Erratics. In Ricci, C.A., The Antarctic Region: Geological Evolution and Process, Terra Antarctica Publication, Siena, pp. 829-834

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19940930

Ending_Date: 19950331

Currentness_Reference:Unknown

Status:

Progress: Complete

Maintenance_and_Update_Frequency: As needed

Spatial_Domain:

Description_of_Geographic_Extent:

Bounding_Coordinates:

West_Bounding_Coordinate: 71.0

East_Bounding_Coordinate: 73.0

North_Bounding_Coordinate: -67.0

South_Bounding_Coordinate: -70.0

Keywords:

Theme:

Theme_Keyword_Thesaurus: GCMD SCIENCE PARAMETERS

Theme_Keyword_Thesaurus: GCMD PLATFORM

Theme_Keyword_Thesaurus: ANCILLARY KEYWORDS

Theme_Keyword_Thesaurus: ISO TOPIC CATEGORY

Theme_Keyword_Thesaurus: DATA SET LANGUAGE

Theme_Keyword: EARTH SCIENCE > PALEOCLIMATE > LAND RECORDS > GLACIATION

Theme_Keyword: EARTH SCIENCE > PALEOCLIMATE > LAND RECORDS > ISOTOPES

Theme_Keyword: FIELD SURVEYS

Theme_Keyword: Altitude

Theme_Keyword: Aluminium

Theme_Keyword: Antarctica

Theme_Keyword: Beryllium

Theme_Keyword: Cosmic Rays

Theme_Keyword: Cosmogenic

Theme_Keyword: Exposure Age

Theme_Keyword: Latitude

Theme_Keyword: Longitude

Theme_Keyword: Sample

Theme_Keyword: Terrestrial Cosmogenic Nuclides

Theme_Keyword: Thickness

Theme_Keyword: CLIMATOLOGY/METEOROLOGY/ATMOSPHERE

Theme_Keyword: GEOSCIENTIFIC INFORMATION

Theme_Keyword: ENGLISH

Place:

Place_Keyword_Thesaurus: GCMD

Place_Keyword: CONTINENT > ANTARCTICA > VESTFOLD HILLS

Place_Keyword: GEOGRAPHIC REGION > POLAR

Access_Constraints: This dataset is not yet publicly available. For details, contact the investigator.

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.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: DEREK FABEL

Contact_Person_Primary:

Contact_Person: JOHN STONE

Contact_Position: INVESTIGATOR

Contact_Position: TECHNICAL CONTACT

Contact_Position: DIF AUTHOR

Contact_Position: INVESTIGATOR

Contact_Position: TECHNICAL CONTACT

Contact_Address:

Address_Type: Mailing and Physical Address

Address: Glasgow University

Address: Department of Geography and Geomatics

City: Glasgow

State_or_Province: Scotland

Postal_Code: G12 8QQ

Country: UNITED KINGDOM

Contact_Address:

Address_Type: Mailing and Physical Address

Address: Department of Earth and Space Sciences and Quaternary Research Center

Address: Box 351310

Address: University of Washington

City: Seattle

State_or_Province: Washington State

Postal_Code: 98195-1310

Country: USA

Contact_Voice_Telephone: +44 (0)141 330 2262

Contact_Voice_Telephone: +1 206 221-6332

Contact_Facsimile_Telephone: +44 (0)141 330 4894

Contact_Facsimile_Telephone: +1 206 543-0489

Contact_Electronic_Mail_Address: dfabel@geog.gla.ac.uk

Contact_Electronic_Mail_Address: stone@geology.washington.edu

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Values provided in temporal coverage are approximate only.

Logical_Consistency_Report:

Not Available

Completeness_Report:

Not Available

Lineage:

Process_Step:

Process_Description:

Not Available

Process_Date: Unknown

Spatial_Reference_Information:

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: AU/AADC > Australian Antarctic Data Centre, Australia

Contact_Person: DATA OFFICER AADC

Contact_Position: DATA CENTER CONTACT

Contact_Address:

Address_Type: Mailing and Physical Address

Address: Australian Antarctic Division

Address: 203 Channel Highway

City: Kingston

State_or_Province: Tasmania

Postal_Code: 7050

Country: Australia

Contact_Voice_Telephone: +61 3 6232 3244

Contact_Facsimile_Telephone: +61 3 6232 3351

Contact_Electronic_Mail_Address: metadata@aad.gov.au

Resource_Description: ASAC_831

Distribution_Liability:

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Standard_Order_Process:

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Format_Name: excel

Transfer_Size: 6 kb

Digital_Transfer_Option:

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http://data.aad.gov.au

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DATA CENTER URL

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http://data.aad.gov.au/aadc/portal/download_file.c...

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Download point for the data

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Access_Instructions:

Public information for ASAC project 831

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Network_Resource_Name:

http://data.aad.gov.au/aadc/metadata/citation.cfm?...

Access_Instructions:

Citation reference for this metadata record and dataset

Fees: Free

Metadata_Reference_Information:

Metadata_Date: 20000808

Metadata_Review_Date: 20100817

Metadata_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: DEREK FABEL

Contact_Position: INVESTIGATOR

Contact_Position: TECHNICAL CONTACT

Contact_Position: DIF AUTHOR

Contact_Address:

Address_Type: Mailing and Physical Address

Address: Glasgow University

Address: Department of Geography and Geomatics

City: Glasgow

State_or_Province: Scotland

Postal_Code: G12 8QQ

Country: UNITED KINGDOM

Contact_Voice_Telephone: +44 (0)141 330 2262

Contact_Facsimile_Telephone: +44 (0)141 330 4894

Contact_Electronic_Mail_Address: dfabel@geog.gla.ac.uk

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time