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| Titel |
Isotopic and lithologic variations of one precisely-dated stalagmite across the Medieval/LIA period from Heilong Cave, central China |
| VerfasserIn |
Y. F. Cui, Y. J. Wang, H. Cheng, K. Zhao, X. G. Kong |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 8, no. 5 ; Nr. 8, no. 5 (2012-10-11), S.1541-1550 |
| Datensatznummer |
250005841
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| Publikation (Nr.) |
 copernicus.org/cp-8-1541-2012.pdf |
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| Zusammenfassung |
| Lithologic and isotopic changes of one stalagmite (224 mm in length) from
Heilong Cave, Central China, are investigated here in order to explore
multiple proxies of monsoon climate. High uranium concentrations (6–10 ppm)
ensure Th-230 dates precisely and resultant chronology ranges from ~790 to 1780 AD across the Medieval Warm Period (MWP) to Little Ice Age
(LIA). Annually resolved oxygen and carbon isotopic data, gray level and
elemental Sr are highly related to macroscopic lithologic changes. A
lamination sequence is composed of alternations of white-porous and
dark-compact calcite clearly discerned on the polished surface. The
dark-compact laminae have low values of gray level, high Sr and δ13C values, indicating periods of low growth rate under dry climate
conditions, and vice versa for the white-porous laminae. This suggests that
changes in hydrology, matter input of drip water and crystallization process
were controlled by cave environments and climates. The alternation of dry
and wet periods with a significant periodicity of ~90 yr, as
indicated by spectral analyses of the multiple proxies, is further supported
by a reconstructed precipitation index from historical documents and
instrumental data extending back to 1470 AD. A strong coherence between
monsoon proxy of calcite δ18O and the other proxies was
observed during the LIA but not during the MWP. This is likely due to
changes in atmospheric circulation pattern at the boundary of MWP/LIA.
When the
Intertropical Convergence Zone shifted southward during the LIA, summer
monsoon precipitation at the cave site was probably dominated by the Mei-Yu,
resulting in water vapor mainly originated from adjacent oceanic sources. |
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