Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling
The Lake Bosumtwi sediment record represents one of the longest and highest-resolution terrestrial records of paleoclimate change available from sub-Saharan Africa. Here we report a new sediment age model framework for the last ~. 45. cal kyr of sedimentation using a combination of high-resolution r...
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ftunivrhodeislan:oai:digitalcommons.uri.edu:gsofacpubs-2637 2024-01-21T10:08:45+01:00 Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling Shanahan, Timothy M. Beck, J. Warren Overpeck, Jonathan T. McKay, Nicholas P. Pigati, Jeffrey S. Peck, John A. Scholz, Christopher A. Heil, Clifford W. King, John 2012-11-15T08:00:00Z https://digitalcommons.uri.edu/gsofacpubs/1668 https://doi.org/10.1016/j.palaeo.2012.08.001 unknown DigitalCommons@URI https://digitalcommons.uri.edu/gsofacpubs/1668 doi:10.1016/j.palaeo.2012.08.001 https://doi.org/10.1016/j.palaeo.2012.08.001 Graduate School of Oceanography Faculty Publications Age model Lake Paleoclimate Radiocarbon West Africa text 2012 ftunivrhodeislan https://doi.org/10.1016/j.palaeo.2012.08.001 2023-12-25T19:09:53Z The Lake Bosumtwi sediment record represents one of the longest and highest-resolution terrestrial records of paleoclimate change available from sub-Saharan Africa. Here we report a new sediment age model framework for the last ~. 45. cal kyr of sedimentation using a combination of high-resolution radiocarbon dating, Bayesian age-depth modeling and lamination counting. Our results highlight the practical limits of these methods for reducing age model uncertainties and suggest that even with very high sampling densities, radiocarbon uncertainties of at least a few hundred years are unavoidable. Age model uncertainties are smallest during the Holocene (205. yr) and the glacial (360. yr) but are large at the base of the record (1660. yr), due to a combination of decreasing sample density, larger calibration uncertainties and increases in radiocarbon age scatter. For portions of the chronology older than ~. 35. cal kyr, additional considerations, such as the use of a low-blank graphitization system and more rigorous sample pretreatment were necessary to generate a reliable age depth model because of the incorporation of small amounts of younger carbon. A comparison of radiocarbon age model results and lamination counts over the time interval ~. 15-30. cal kyr agree with an overall discrepancy of ~. 10% and display similar changes in sedimentation rate, supporting the annual nature of sediment laminations in the early part of the record. Changes in sedimentation rates reconstructed from the age-depth model indicate that intervals of enhanced sediment delivery occurred at 16-19, 24 and 29-31. cal kyr, broadly synchronous with reconstructed drought episodes elsewhere in northern West Africa and potentially, with changes in Atlantic meridional heat transport during North Atlantic Heinrich events. These data suggest that millennial-scale drought events in the West African monsoon region were latitudinally extensive, reaching within several hundred kilometers of the Guinea coast. This is inconsistent with a simple ... Text North Atlantic University of Rhode Island: DigitalCommons@URI Palaeogeography, Palaeoclimatology, Palaeoecology 361-362 49 60 |
institution |
Open Polar |
collection |
University of Rhode Island: DigitalCommons@URI |
op_collection_id |
ftunivrhodeislan |
language |
unknown |
topic |
Age model Lake Paleoclimate Radiocarbon West Africa |
spellingShingle |
Age model Lake Paleoclimate Radiocarbon West Africa Shanahan, Timothy M. Beck, J. Warren Overpeck, Jonathan T. McKay, Nicholas P. Pigati, Jeffrey S. Peck, John A. Scholz, Christopher A. Heil, Clifford W. King, John Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling |
topic_facet |
Age model Lake Paleoclimate Radiocarbon West Africa |
description |
The Lake Bosumtwi sediment record represents one of the longest and highest-resolution terrestrial records of paleoclimate change available from sub-Saharan Africa. Here we report a new sediment age model framework for the last ~. 45. cal kyr of sedimentation using a combination of high-resolution radiocarbon dating, Bayesian age-depth modeling and lamination counting. Our results highlight the practical limits of these methods for reducing age model uncertainties and suggest that even with very high sampling densities, radiocarbon uncertainties of at least a few hundred years are unavoidable. Age model uncertainties are smallest during the Holocene (205. yr) and the glacial (360. yr) but are large at the base of the record (1660. yr), due to a combination of decreasing sample density, larger calibration uncertainties and increases in radiocarbon age scatter. For portions of the chronology older than ~. 35. cal kyr, additional considerations, such as the use of a low-blank graphitization system and more rigorous sample pretreatment were necessary to generate a reliable age depth model because of the incorporation of small amounts of younger carbon. A comparison of radiocarbon age model results and lamination counts over the time interval ~. 15-30. cal kyr agree with an overall discrepancy of ~. 10% and display similar changes in sedimentation rate, supporting the annual nature of sediment laminations in the early part of the record. Changes in sedimentation rates reconstructed from the age-depth model indicate that intervals of enhanced sediment delivery occurred at 16-19, 24 and 29-31. cal kyr, broadly synchronous with reconstructed drought episodes elsewhere in northern West Africa and potentially, with changes in Atlantic meridional heat transport during North Atlantic Heinrich events. These data suggest that millennial-scale drought events in the West African monsoon region were latitudinally extensive, reaching within several hundred kilometers of the Guinea coast. This is inconsistent with a simple ... |
format |
Text |
author |
Shanahan, Timothy M. Beck, J. Warren Overpeck, Jonathan T. McKay, Nicholas P. Pigati, Jeffrey S. Peck, John A. Scholz, Christopher A. Heil, Clifford W. King, John |
author_facet |
Shanahan, Timothy M. Beck, J. Warren Overpeck, Jonathan T. McKay, Nicholas P. Pigati, Jeffrey S. Peck, John A. Scholz, Christopher A. Heil, Clifford W. King, John |
author_sort |
Shanahan, Timothy M. |
title |
Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling |
title_short |
Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling |
title_full |
Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling |
title_fullStr |
Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling |
title_full_unstemmed |
Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling |
title_sort |
late quaternary sedimentological and climate changes at lake bosumtwi ghana: new constraints from laminae analysis and radiocarbon age modeling |
publisher |
DigitalCommons@URI |
publishDate |
2012 |
url |
https://digitalcommons.uri.edu/gsofacpubs/1668 https://doi.org/10.1016/j.palaeo.2012.08.001 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Graduate School of Oceanography Faculty Publications |
op_relation |
https://digitalcommons.uri.edu/gsofacpubs/1668 doi:10.1016/j.palaeo.2012.08.001 https://doi.org/10.1016/j.palaeo.2012.08.001 |
op_doi |
https://doi.org/10.1016/j.palaeo.2012.08.001 |
container_title |
Palaeogeography, Palaeoclimatology, Palaeoecology |
container_volume |
361-362 |
container_start_page |
49 |
op_container_end_page |
60 |
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1788699564457328640 |