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A Holocene lacustrine record in the central North Atlantic: proxies for volcanic activity, short-term NAO mode variability, and long-term precipitation changes

Björck, Svante LU ; Rittenour, Tammy LU ; Rosen, P ; Franca, Z ; Möller, Per LU orcid ; Snowball, Ian LU ; Wastegard, S ; Bennike, O and Kromer, B (2006) In Quaternary Science Reviews 25(1-2). p.9-32
Abstract
Lake and peat corings on three Azores islands in the central North Atlantic, resulted in the discovery of a 6000 year long lacustrine sequence in a small crater lake, Lake Caveiro, on the island of Pico. This island is dominated by Pico mountain (2351 m), Portugal's highest mountain, and the lake site is situated at 903 in asl. Two sediment profiles, one central and one littoral, were sampled. Due to large facial shifts and disconformities in the littoral cores the analyses were concentrated on the central core; only the earliest 1000 years of the littoral core were studied to complement the central profile. We used sedimentology, geochemistry, diatom analyses, magnetic properties, and multivariate statistics, together with C-14 and Pb-210... (More)
Lake and peat corings on three Azores islands in the central North Atlantic, resulted in the discovery of a 6000 year long lacustrine sequence in a small crater lake, Lake Caveiro, on the island of Pico. This island is dominated by Pico mountain (2351 m), Portugal's highest mountain, and the lake site is situated at 903 in asl. Two sediment profiles, one central and one littoral, were sampled. Due to large facial shifts and disconformities in the littoral cores the analyses were concentrated on the central core; only the earliest 1000 years of the littoral core were studied to complement the central profile. We used sedimentology, geochemistry, diatom analyses, magnetic properties, and multivariate statistics, together with C-14 and Pb-210 dating techniques, to analyse the environmental history of the lake. Volcanic activity seems to have had a dominating impact on sediment changes and partly also on the diatom assemblages; a large number of tephras are found and seem to be connected with large (diatom) inferred pH variations. However, by a combination of methods, including multivariate techniques, we infer that precipitation changes can be detected through the volcanic noise. In the youngest part of the record (AD 1600-2000), with its decadal resolution, these humidity variations seem partly related to shifts in dominating NAO mode. The more long-term precipitation changes further back in time (350-5100 cal yr BP) roughly correspond to the well-known North Atlantic drift-ice variations as well as other North Atlantic records; low precipitation during drift-ice periods. We think these alterations were driven by changes in the thermolialine circulation as large-scale equivalences to the Great Salt Anomaly; low sea surface A temperatures and changes in circulation patterns of the central North Atlantic decreased the regional precipitation. Cooler/drier periods occurred 400-800, 1300-1800, 2600-3000, 3300-3400 and possibly also 4400-4600 cal yr BP,. while 300-400, 900-1000, 2000-2400, 3100-3200, 3800-4000 and 4700-5000 cal yr BP seem to have been more humid phases on the Azores. (c) 2005 Elsevier Ltd. All rights reserved. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Quaternary Science Reviews
volume
25
issue
1-2
pages
9 - 32
publisher
Elsevier
external identifiers
  • wos:000234983000002
  • scopus:30044444599
ISSN
0277-3791
DOI
10.1016/j.quascirev.2005.08.008
language
English
LU publication?
yes
id
82cd3abf-4756-4362-9e44-2fda4444fff1 (old id 418330)
date added to LUP
2016-04-01 11:49:56
date last changed
2021-10-06 02:11:57
@article{82cd3abf-4756-4362-9e44-2fda4444fff1,
  abstract     = {Lake and peat corings on three Azores islands in the central North Atlantic, resulted in the discovery of a 6000 year long lacustrine sequence in a small crater lake, Lake Caveiro, on the island of Pico. This island is dominated by Pico mountain (2351 m), Portugal's highest mountain, and the lake site is situated at 903 in asl. Two sediment profiles, one central and one littoral, were sampled. Due to large facial shifts and disconformities in the littoral cores the analyses were concentrated on the central core; only the earliest 1000 years of the littoral core were studied to complement the central profile. We used sedimentology, geochemistry, diatom analyses, magnetic properties, and multivariate statistics, together with C-14 and Pb-210 dating techniques, to analyse the environmental history of the lake. Volcanic activity seems to have had a dominating impact on sediment changes and partly also on the diatom assemblages; a large number of tephras are found and seem to be connected with large (diatom) inferred pH variations. However, by a combination of methods, including multivariate techniques, we infer that precipitation changes can be detected through the volcanic noise. In the youngest part of the record (AD 1600-2000), with its decadal resolution, these humidity variations seem partly related to shifts in dominating NAO mode. The more long-term precipitation changes further back in time (350-5100 cal yr BP) roughly correspond to the well-known North Atlantic drift-ice variations as well as other North Atlantic records; low precipitation during drift-ice periods. We think these alterations were driven by changes in the thermolialine circulation as large-scale equivalences to the Great Salt Anomaly; low sea surface A temperatures and changes in circulation patterns of the central North Atlantic decreased the regional precipitation. Cooler/drier periods occurred 400-800, 1300-1800, 2600-3000, 3300-3400 and possibly also 4400-4600 cal yr BP,. while 300-400, 900-1000, 2000-2400, 3100-3200, 3800-4000 and 4700-5000 cal yr BP seem to have been more humid phases on the Azores. (c) 2005 Elsevier Ltd. All rights reserved.},
  author       = {Björck, Svante and Rittenour, Tammy and Rosen, P and Franca, Z and Möller, Per and Snowball, Ian and Wastegard, S and Bennike, O and Kromer, B},
  issn         = {0277-3791},
  language     = {eng},
  number       = {1-2},
  pages        = {9--32},
  publisher    = {Elsevier},
  series       = {Quaternary Science Reviews},
  title        = {A Holocene lacustrine record in the central North Atlantic: proxies for volcanic activity, short-term NAO mode variability, and long-term precipitation changes},
  url          = {http://dx.doi.org/10.1016/j.quascirev.2005.08.008},
  doi          = {10.1016/j.quascirev.2005.08.008},
  volume       = {25},
  year         = {2006},
}