Development of an improved ramped pyrolysis method for radiocarbon dating and application to Antarctic sediments
Archives of the retreat history of the Antarctic Ice Sheet since the Last Glacial Maximum (~20,000 years ago) are preserved in marine sediment cores from around the margins of Antarctica, but accurate dating methods remain elusive in many areas. Radiocarbon dating of key lithofacies transitions indi...
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ftvuwellington:oai:researcharchive.vuw.ac.nz:10063/8932 2023-08-15T12:37:37+02:00 Development of an improved ramped pyrolysis method for radiocarbon dating and application to Antarctic sediments Reeve, Simon McKay, Robert Turnbull, Jocelyn Levy, Richard 2020 http://researcharchive.vuw.ac.nz/handle/10063/8932 en eng Victoria University of Wellington http://researcharchive.vuw.ac.nz/handle/10063/8932 pyrolysis radiocarbon sediment Antarctic Text Masters 2020 ftvuwellington 2023-07-25T17:29:53Z Archives of the retreat history of the Antarctic Ice Sheet since the Last Glacial Maximum (~20,000 years ago) are preserved in marine sediment cores from around the margins of Antarctica, but accurate dating methods remain elusive in many areas. Radiocarbon dating of key lithofacies transitions indicative of grounding-line retreat is problematic due to pervasive reworking issues in glacimarine sediments. Bulk sediment material can be radiocarbon dated but yields ages which are not indicative of the time of sedimentation due to the presence of reworked carbon material from pre-Last Glacial Maximum times. Consequently, development of methods to date only the autochthonous carbon component of these sediments are required to date the retreat of the Last Glacial Maximum ice sheet in Antarctica. A new radiocarbon dating capability has been developed at Rafter Radiocarbon Laboratory (RRL), National Isotope Centre, GNS Science, Lower Hutt, in the course of this study. This has entailed designing, building and testing a ramped pyrolysis (RP) system, in which sedimentary material is heated from ambient to ~1000oC in the absence of oxygen (pyrolysed), with the carbon liberated during pyrolysis being combined with oxygen at a temperature of ~800oC to produce CO2. The amount of CO2 produced is measured by a gas analyser and the CO2 is captured in a vacuum line. The method exploits the thermochemical behaviour of degraded organic carbon. Organic carbon which has been least degraded with time breaks down earliest under pyrolysis, so CO2 captured from this fraction most closely approximates the time of deposition of the sediment. CO2 captured at higher temperatures represents more degraded carbon-containing fractions and yields older ages. The RP system includes a gas delivery system to deliver ultra-high purity He (carrier gas) and O2, a furnace system in which to pyrolyse sample material and oxidise the liberated carbon, a CO2 detection system to measure the CO2 produced and a vacuum line system to enable simultaneous ... Master Thesis Antarc* Antarctic Antarctica Ice Sheet Victoria University of Wellington: ResearchArchive Antarctic Rafter ENVELOPE(-101.146,-101.146,55.620,55.620) The Antarctic |
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Victoria University of Wellington: ResearchArchive |
op_collection_id |
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English |
topic |
pyrolysis radiocarbon sediment Antarctic |
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pyrolysis radiocarbon sediment Antarctic Reeve, Simon Development of an improved ramped pyrolysis method for radiocarbon dating and application to Antarctic sediments |
topic_facet |
pyrolysis radiocarbon sediment Antarctic |
description |
Archives of the retreat history of the Antarctic Ice Sheet since the Last Glacial Maximum (~20,000 years ago) are preserved in marine sediment cores from around the margins of Antarctica, but accurate dating methods remain elusive in many areas. Radiocarbon dating of key lithofacies transitions indicative of grounding-line retreat is problematic due to pervasive reworking issues in glacimarine sediments. Bulk sediment material can be radiocarbon dated but yields ages which are not indicative of the time of sedimentation due to the presence of reworked carbon material from pre-Last Glacial Maximum times. Consequently, development of methods to date only the autochthonous carbon component of these sediments are required to date the retreat of the Last Glacial Maximum ice sheet in Antarctica. A new radiocarbon dating capability has been developed at Rafter Radiocarbon Laboratory (RRL), National Isotope Centre, GNS Science, Lower Hutt, in the course of this study. This has entailed designing, building and testing a ramped pyrolysis (RP) system, in which sedimentary material is heated from ambient to ~1000oC in the absence of oxygen (pyrolysed), with the carbon liberated during pyrolysis being combined with oxygen at a temperature of ~800oC to produce CO2. The amount of CO2 produced is measured by a gas analyser and the CO2 is captured in a vacuum line. The method exploits the thermochemical behaviour of degraded organic carbon. Organic carbon which has been least degraded with time breaks down earliest under pyrolysis, so CO2 captured from this fraction most closely approximates the time of deposition of the sediment. CO2 captured at higher temperatures represents more degraded carbon-containing fractions and yields older ages. The RP system includes a gas delivery system to deliver ultra-high purity He (carrier gas) and O2, a furnace system in which to pyrolyse sample material and oxidise the liberated carbon, a CO2 detection system to measure the CO2 produced and a vacuum line system to enable simultaneous ... |
author2 |
McKay, Robert Turnbull, Jocelyn Levy, Richard |
format |
Master Thesis |
author |
Reeve, Simon |
author_facet |
Reeve, Simon |
author_sort |
Reeve, Simon |
title |
Development of an improved ramped pyrolysis method for radiocarbon dating and application to Antarctic sediments |
title_short |
Development of an improved ramped pyrolysis method for radiocarbon dating and application to Antarctic sediments |
title_full |
Development of an improved ramped pyrolysis method for radiocarbon dating and application to Antarctic sediments |
title_fullStr |
Development of an improved ramped pyrolysis method for radiocarbon dating and application to Antarctic sediments |
title_full_unstemmed |
Development of an improved ramped pyrolysis method for radiocarbon dating and application to Antarctic sediments |
title_sort |
development of an improved ramped pyrolysis method for radiocarbon dating and application to antarctic sediments |
publisher |
Victoria University of Wellington |
publishDate |
2020 |
url |
http://researcharchive.vuw.ac.nz/handle/10063/8932 |
long_lat |
ENVELOPE(-101.146,-101.146,55.620,55.620) |
geographic |
Antarctic Rafter The Antarctic |
geographic_facet |
Antarctic Rafter The Antarctic |
genre |
Antarc* Antarctic Antarctica Ice Sheet |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet |
op_relation |
http://researcharchive.vuw.ac.nz/handle/10063/8932 |
_version_ |
1774294734218461184 |