Paleoclimatic Events of the Past 15,000 Years Inferred from Beryllium-10 Chronologies of Moraines in New Zealand
Detailed records of past climate variations can help to reveal the causes of ice-age climate cycles and place the global warming of recent decades in a broader context. My goal is to determine the timing of deglacial and Holocene climate changes in the Southern Hemisphere mid-latitudes. My approach...
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ftmaineuniv:oai:digitalcommons.library.umaine.edu:etd-3237 2023-06-11T04:13:54+02:00 Paleoclimatic Events of the Past 15,000 Years Inferred from Beryllium-10 Chronologies of Moraines in New Zealand Buttersworth Koffman, Tobias Nicholas 2014-08-01T07:00:00Z application/pdf https://digitalcommons.library.umaine.edu/etd/2199 https://digitalcommons.library.umaine.edu/context/etd/article/3237/viewcontent/KoffmanTNB2014_OCR.pdf unknown DigitalCommons@UMaine https://digitalcommons.library.umaine.edu/etd/2199 https://digitalcommons.library.umaine.edu/context/etd/article/3237/viewcontent/KoffmanTNB2014_OCR.pdf Electronic Theses and Dissertations Paleoclimatology Holocene Moraines New Zealand Climate Earth Sciences text 2014 ftmaineuniv 2023-05-04T18:02:14Z Detailed records of past climate variations can help to reveal the causes of ice-age climate cycles and place the global warming of recent decades in a broader context. My goal is to determine the timing of deglacial and Holocene climate changes in the Southern Hemisphere mid-latitudes. My approach is to develop novel moraine chronologies based on beryllium-10 surface-exposure dating, together with glaciological model simulations to determine past temperature. I measured the ages of two sequences of glacial landforms: one in the Rakaia River valley that records glacier-length changes during the past 15,000 years, and a second in front of the Classen Glacier that shows ice-margin fluctuations during the past 5200 years. Moraines in New Zealand’s Rakaia River valley record rapid recession of the Rakaia glacier at the end of the last ice age between ~18,000 and ~15,000 years ago in response to an inferred temperature rise of 4°C. Deglaciation was interrupted by two glacier still stands at 13,950 ±130 and 13,170 ± 260 years ago. The Rakaia glacier then receded after ~13,200 years ago, with brief pauses at 12,150 ± 200 and 11,610 ± 160 years ago. Net glacier thinning of ~250 m between 13,200 and 11,600 years ago occurred in response to a temperature rise of ~1°C. Additional thinning by ~8000 years ago implies warming of ~ 0.5°C, which separated the Lyell Glacier at the valley head from tributaries in the lower Rakaia River valley. Culminations of late-Holocene advances of Lyell Glacier occurred at 574 ± 30, 315 ± 8, 273 ± 28, and 141 ± 13 years before 2011 C.E. Moraines of the Classen Glacier document greater ice extent at 5260 ±130 years ago than at any later interval. Successively less extensive advances culminated at 5160 ± 77, 462 ± 25, 334 ± 35, 287 ± 30, and 220 ± 13 years before 2011 C.E., respectively. I conclude that New Zealand glacier retreat coincided with Northem-Hemisphere cooling on millennial to decadal time scales between 18,000 and 100 years ago, a pattern that differs from worldwide glacier ... Text Lyell Glacier The University of Maine: DigitalCommons@UMaine Lyell Glacier ENVELOPE(-36.617,-36.617,-54.299,-54.299) New Zealand |
institution |
Open Polar |
collection |
The University of Maine: DigitalCommons@UMaine |
op_collection_id |
ftmaineuniv |
language |
unknown |
topic |
Paleoclimatology Holocene Moraines New Zealand Climate Earth Sciences |
spellingShingle |
Paleoclimatology Holocene Moraines New Zealand Climate Earth Sciences Buttersworth Koffman, Tobias Nicholas Paleoclimatic Events of the Past 15,000 Years Inferred from Beryllium-10 Chronologies of Moraines in New Zealand |
topic_facet |
Paleoclimatology Holocene Moraines New Zealand Climate Earth Sciences |
description |
Detailed records of past climate variations can help to reveal the causes of ice-age climate cycles and place the global warming of recent decades in a broader context. My goal is to determine the timing of deglacial and Holocene climate changes in the Southern Hemisphere mid-latitudes. My approach is to develop novel moraine chronologies based on beryllium-10 surface-exposure dating, together with glaciological model simulations to determine past temperature. I measured the ages of two sequences of glacial landforms: one in the Rakaia River valley that records glacier-length changes during the past 15,000 years, and a second in front of the Classen Glacier that shows ice-margin fluctuations during the past 5200 years. Moraines in New Zealand’s Rakaia River valley record rapid recession of the Rakaia glacier at the end of the last ice age between ~18,000 and ~15,000 years ago in response to an inferred temperature rise of 4°C. Deglaciation was interrupted by two glacier still stands at 13,950 ±130 and 13,170 ± 260 years ago. The Rakaia glacier then receded after ~13,200 years ago, with brief pauses at 12,150 ± 200 and 11,610 ± 160 years ago. Net glacier thinning of ~250 m between 13,200 and 11,600 years ago occurred in response to a temperature rise of ~1°C. Additional thinning by ~8000 years ago implies warming of ~ 0.5°C, which separated the Lyell Glacier at the valley head from tributaries in the lower Rakaia River valley. Culminations of late-Holocene advances of Lyell Glacier occurred at 574 ± 30, 315 ± 8, 273 ± 28, and 141 ± 13 years before 2011 C.E. Moraines of the Classen Glacier document greater ice extent at 5260 ±130 years ago than at any later interval. Successively less extensive advances culminated at 5160 ± 77, 462 ± 25, 334 ± 35, 287 ± 30, and 220 ± 13 years before 2011 C.E., respectively. I conclude that New Zealand glacier retreat coincided with Northem-Hemisphere cooling on millennial to decadal time scales between 18,000 and 100 years ago, a pattern that differs from worldwide glacier ... |
format |
Text |
author |
Buttersworth Koffman, Tobias Nicholas |
author_facet |
Buttersworth Koffman, Tobias Nicholas |
author_sort |
Buttersworth Koffman, Tobias Nicholas |
title |
Paleoclimatic Events of the Past 15,000 Years Inferred from Beryllium-10 Chronologies of Moraines in New Zealand |
title_short |
Paleoclimatic Events of the Past 15,000 Years Inferred from Beryllium-10 Chronologies of Moraines in New Zealand |
title_full |
Paleoclimatic Events of the Past 15,000 Years Inferred from Beryllium-10 Chronologies of Moraines in New Zealand |
title_fullStr |
Paleoclimatic Events of the Past 15,000 Years Inferred from Beryllium-10 Chronologies of Moraines in New Zealand |
title_full_unstemmed |
Paleoclimatic Events of the Past 15,000 Years Inferred from Beryllium-10 Chronologies of Moraines in New Zealand |
title_sort |
paleoclimatic events of the past 15,000 years inferred from beryllium-10 chronologies of moraines in new zealand |
publisher |
DigitalCommons@UMaine |
publishDate |
2014 |
url |
https://digitalcommons.library.umaine.edu/etd/2199 https://digitalcommons.library.umaine.edu/context/etd/article/3237/viewcontent/KoffmanTNB2014_OCR.pdf |
long_lat |
ENVELOPE(-36.617,-36.617,-54.299,-54.299) |
geographic |
Lyell Glacier New Zealand |
geographic_facet |
Lyell Glacier New Zealand |
genre |
Lyell Glacier |
genre_facet |
Lyell Glacier |
op_source |
Electronic Theses and Dissertations |
op_relation |
https://digitalcommons.library.umaine.edu/etd/2199 https://digitalcommons.library.umaine.edu/context/etd/article/3237/viewcontent/KoffmanTNB2014_OCR.pdf |
_version_ |
1768391315518652416 |