10 Be, 14 C and U-Th decay series nuclides and δ 18 O in a box core from the Central North Atlantic
The stratigraphy of several radioisotopes has been determined in an undisturbed core from the central north Atlantic ( 14 C, 238 U, 230 Th, 232 Th, 226 Ra, 210 Pb, 10 Be). Carbon-14 indicates a sedimentation rate of 1 cm 1000 yrs −1 . The core represents about 30,000 years. The oxygen isotope signal...
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ftindianacasci:oai:repository.ias.ac.in:49776 2023-05-15T17:31:40+02:00 10 Be, 14 C and U-Th decay series nuclides and δ 18 O in a box core from the Central North Atlantic Somayajulu, B. L. K. Sharma, P. Berger, W. H. 1984-01 http://repository.ias.ac.in/49776/ http://www.sciencedirect.com/science/article/pii/0025322784900367 unknown Elsevier Science Somayajulu, B. L. K. Sharma, P. Berger, W. H. (1984) 10Be, 14C and U-Th decay series nuclides and δ18O in a box core from the Central North Atlantic Marine Geology, 54 (3-4). pp. 169-180. ISSN 0025-3227 QE Geology Article PeerReviewed 1984 ftindianacasci 2013-01-20T11:44:17Z The stratigraphy of several radioisotopes has been determined in an undisturbed core from the central north Atlantic ( 14 C, 238 U, 230 Th, 232 Th, 226 Ra, 210 Pb, 10 Be). Carbon-14 indicates a sedimentation rate of 1 cm 1000 yrs −1 . The core represents about 30,000 years. The oxygen isotope signal agrees with this scale. The δ 18 O range is about 1.5%., from glacial to Holocene. The maximum change is near 11,000 years B.P. Mixing effects are minor because of the low fertility of the overlying waters. Excess lead-210 shows a minimum between 1 and 2 cm depth, and a maximum immediately below. It does not yield a diffusion coefficient for the Goldberg and Koide (1962) mixing model. The 10 Be concentration in the Holocene sediment (on a CaCO 3 -free basis) is somewhat higher than that deposited during the previous cold period. However, both clay and 10 Be deposition rates are lower by a factor of over two during the Holocene. The source of the excess 10 Be in the glacial section could be a continental reservoir or increased cosmic ray production. The U and Th concentrations as well as the excess 230 Th/ 232 Th activity ratios of the sediment deposited during the Holocene are higher (by 30-100%) than in glacial sediments. Again, this is in contrast to the deposition rates of U and Th, which are lower in the Holocene by a factor of about two. The most reliable signals are the radiocarbon and the oxygen isotope stratigraphy. Article in Journal/Newspaper North Atlantic Indian Academy of Sciences: Publication of Fellows |
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Indian Academy of Sciences: Publication of Fellows |
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topic |
QE Geology |
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QE Geology Somayajulu, B. L. K. Sharma, P. Berger, W. H. 10 Be, 14 C and U-Th decay series nuclides and δ 18 O in a box core from the Central North Atlantic |
topic_facet |
QE Geology |
description |
The stratigraphy of several radioisotopes has been determined in an undisturbed core from the central north Atlantic ( 14 C, 238 U, 230 Th, 232 Th, 226 Ra, 210 Pb, 10 Be). Carbon-14 indicates a sedimentation rate of 1 cm 1000 yrs −1 . The core represents about 30,000 years. The oxygen isotope signal agrees with this scale. The δ 18 O range is about 1.5%., from glacial to Holocene. The maximum change is near 11,000 years B.P. Mixing effects are minor because of the low fertility of the overlying waters. Excess lead-210 shows a minimum between 1 and 2 cm depth, and a maximum immediately below. It does not yield a diffusion coefficient for the Goldberg and Koide (1962) mixing model. The 10 Be concentration in the Holocene sediment (on a CaCO 3 -free basis) is somewhat higher than that deposited during the previous cold period. However, both clay and 10 Be deposition rates are lower by a factor of over two during the Holocene. The source of the excess 10 Be in the glacial section could be a continental reservoir or increased cosmic ray production. The U and Th concentrations as well as the excess 230 Th/ 232 Th activity ratios of the sediment deposited during the Holocene are higher (by 30-100%) than in glacial sediments. Again, this is in contrast to the deposition rates of U and Th, which are lower in the Holocene by a factor of about two. The most reliable signals are the radiocarbon and the oxygen isotope stratigraphy. |
format |
Article in Journal/Newspaper |
author |
Somayajulu, B. L. K. Sharma, P. Berger, W. H. |
author_facet |
Somayajulu, B. L. K. Sharma, P. Berger, W. H. |
author_sort |
Somayajulu, B. L. K. |
title |
10 Be, 14 C and U-Th decay series nuclides and δ 18 O in a box core from the Central North Atlantic |
title_short |
10 Be, 14 C and U-Th decay series nuclides and δ 18 O in a box core from the Central North Atlantic |
title_full |
10 Be, 14 C and U-Th decay series nuclides and δ 18 O in a box core from the Central North Atlantic |
title_fullStr |
10 Be, 14 C and U-Th decay series nuclides and δ 18 O in a box core from the Central North Atlantic |
title_full_unstemmed |
10 Be, 14 C and U-Th decay series nuclides and δ 18 O in a box core from the Central North Atlantic |
title_sort |
10 be, 14 c and u-th decay series nuclides and δ 18 o in a box core from the central north atlantic |
publisher |
Elsevier Science |
publishDate |
1984 |
url |
http://repository.ias.ac.in/49776/ http://www.sciencedirect.com/science/article/pii/0025322784900367 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
Somayajulu, B. L. K. Sharma, P. Berger, W. H. (1984) 10Be, 14C and U-Th decay series nuclides and δ18O in a box core from the Central North Atlantic Marine Geology, 54 (3-4). pp. 169-180. ISSN 0025-3227 |
_version_ |
1766129348373381120 |