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

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Identification_Information:
Citation:
Citation_Information:
Originator: Fabel, D. and Stone, J.
Publication_Date: 20161214
Title: Rates of Quaternary Ice Movement Across the Vestfold Hills from Exposure Age Dating.
Edition:
Geospatial_Data_Presentation_Form:
Series_Information:
Series_Name: CAASM Metadata
Issue_Identification:
Publication_Information:
Publication_Place:
Publisher: Australian Antarctic Data Centre
Other_Citation_Details:
Online_Linkage: https://data.aad.gov.au/aadc/metadata/metadata_redirect.cfm?md=/AMD/AU/ASAC_831
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 accelerator 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. The Antarctic Region: Geological Evolution and Process, Terra Antarctica Publication, Siena 829-834 Ricci, C.A. (ed)
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: NULL
Theme_Keyword: NULL
Theme_Keyword: ENGLISH
Place:
Place_Keyword_Thesaurus: GCMD
Place_Keyword: CONTINENT > ANTARCTICA > VESTFOLD HILLS
Place_Keyword: GEOGRAPHIC REGION > POLAR
Access_Constraints: These data are publicly 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 provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_831 when using these data.
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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
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Spatial_Reference_Information:
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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:
Not Available
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: Word, PDF
Transfer_Size: 121 kb
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
http://data.aad.gov.au
Access_Instructions:
DATA CENTER URL
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
http://data.aad.gov.au/aadc/portal/download_file.c...
Access_Instructions:
Download point for the data
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
https://secure3.aad.gov.au/proms/public/projects/r...
Access_Instructions:
Public information for ASAC project 831
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
http://data.aad.gov.au/aadc/metadata/citation.cfm?...
Access_Instructions:
Citation reference for this metadata record and dataset
Fees: Free
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Metadata_Reference_Information:
Metadata_Date: 20000808
Metadata_Review_Date: 20170126
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: GCMD User Support Office
Contact_Organization: NASA Global Change Master Directory
Contact_Address:
Address_Type: Mailing and Physical Address
Address: Not Available
City: Lanham
State_or_Province: MD
Postal_Code: 20706
Country: USA
Contact_Voice_Telephone: Not Available
Contact_Electronic_Mail_Address: gcmduso@gcmd.gsfc.nasa.gov
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
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