A high-resolution, absolute-dated Holocene and deglacial Asian monsoon record from Dongge Cave, China

A high-resolution, absolute-dated Holocene and deglacial Asian monsoon record from Dongge Cave,... We present a continuous record of the Asian monsoon over the last 16 ka from δ 18 O measurements of stalagmite calcite. Over 900 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise 230 Th dates. δ 18 O and therefore Asian monsoon intensity generally follows changes in insolation, although changes in δ 18 O are generally accommodated in abrupt shifts in contrast to smoothly varying insolation, indicating that threshold effects may be important. δ 18 O decreased dramatically (∼3‰) at the start of the Holocene (∼11.5 ka) and remained low for ∼6 ka. Four positive δ 18 O events centered at 11225±97 yr BP (1.05‰), 10880±117 yr BP (1.15‰), 9165±75 yr BP (1.4‰), and a double event centered at 8260±64 yr BP (1.1‰) and 8080±74 yr BP (1.0‰) punctuated this period of high monsoon intensity. All four events correlate within error with climate changes in Greenland ice cores. Thus, the relationship between the Asian monsoon and the North Atlantic observed during the glacial period appears to continue into the early Holocene. In addition, three of the four events correlate within error with outburst events from Lake Agassiz. The decline of monsoon intensity in the mid-late Holocene is characterized by an abrupt positive shift in δ 18 O which occurs at 3550±59 yr BP (1.1‰ in ∼100 yr). In addition, the Holocene is punctuated by numerous centennial- and multi-decadal-scale events (amplitudes 0.5 to 1‰) up to half the amplitude of the glacial interstadial events seen in the last glacial period. Thus, Holocene centennial- and multi-decadal-scale monsoon variability is significant, although not as large as glacial millennial-scale variability. The monsoon shows a strong connection with northern South American hydrological changes related by changes in ITCZ position. Spectral analysis of the δ 18 O record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing. However, there are numerous other significant peaks including peaks at El Niño frequencies (observed for high-resolution portions of the record between 8110 and 8250 yr) which suggest that changes in oceanic and atmospheric circulation patterns in addition to those forced by solar changes are important in controlling Holocene monsoon climate. In addition, for this high-resolution portion, we observe a distinctive biennial oscillation of the Asian monsoon, which has been associated with the Tropospheric Biennial Oscillation (TBO). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Earth and Planetary Science Letters Elsevier

A high-resolution, absolute-dated Holocene and deglacial Asian monsoon record from Dongge Cave, China

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Publisher
Elsevier
Copyright
Copyright © 2005 Elsevier B.V.
ISSN
0012-821X
eISSN
1385-013X
D.O.I.
10.1016/j.epsl.2005.01.036
Publisher site
See Article on Publisher Site

Abstract

We present a continuous record of the Asian monsoon over the last 16 ka from δ 18 O measurements of stalagmite calcite. Over 900 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise 230 Th dates. δ 18 O and therefore Asian monsoon intensity generally follows changes in insolation, although changes in δ 18 O are generally accommodated in abrupt shifts in contrast to smoothly varying insolation, indicating that threshold effects may be important. δ 18 O decreased dramatically (∼3‰) at the start of the Holocene (∼11.5 ka) and remained low for ∼6 ka. Four positive δ 18 O events centered at 11225±97 yr BP (1.05‰), 10880±117 yr BP (1.15‰), 9165±75 yr BP (1.4‰), and a double event centered at 8260±64 yr BP (1.1‰) and 8080±74 yr BP (1.0‰) punctuated this period of high monsoon intensity. All four events correlate within error with climate changes in Greenland ice cores. Thus, the relationship between the Asian monsoon and the North Atlantic observed during the glacial period appears to continue into the early Holocene. In addition, three of the four events correlate within error with outburst events from Lake Agassiz. The decline of monsoon intensity in the mid-late Holocene is characterized by an abrupt positive shift in δ 18 O which occurs at 3550±59 yr BP (1.1‰ in ∼100 yr). In addition, the Holocene is punctuated by numerous centennial- and multi-decadal-scale events (amplitudes 0.5 to 1‰) up to half the amplitude of the glacial interstadial events seen in the last glacial period. Thus, Holocene centennial- and multi-decadal-scale monsoon variability is significant, although not as large as glacial millennial-scale variability. The monsoon shows a strong connection with northern South American hydrological changes related by changes in ITCZ position. Spectral analysis of the δ 18 O record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing. However, there are numerous other significant peaks including peaks at El Niño frequencies (observed for high-resolution portions of the record between 8110 and 8250 yr) which suggest that changes in oceanic and atmospheric circulation patterns in addition to those forced by solar changes are important in controlling Holocene monsoon climate. In addition, for this high-resolution portion, we observe a distinctive biennial oscillation of the Asian monsoon, which has been associated with the Tropospheric Biennial Oscillation (TBO).

Journal

Earth and Planetary Science LettersElsevier

Published: Apr 30, 2005

References

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