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| Titel |
Pluvial Period over NE Brazil linked to Heinrich Stadial Event 1 |
| VerfasserIn |
Kathleen A. Wendt, Akemi Berry, Anamaria Häuselmann, Dominik Fleitmann, Xianfeng Wang, Augusto S. Auler, Hai Cheng, R. Lawrence Edwards |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130811
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| Publikation (Nr.) |
 EGU/EGU2016-11124.pdf |
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| Zusammenfassung |
| The precise timing of Heinrich Stadial (HS) 1 and its impact on tropical regions remain a
topic of active debate. We present a high-resolution precipitation record of HS-1 using a
stalagmite collected from Toca da Barriguda cave located in the interior of NE
Brazil (40o51’39”W 10o09’36”S, 600m asl). Stalagmite growth in this region is
caused by increased rainfall due to a southerly displacement of the Intertropical
Convergence Zone (ITCZ) during HS Events. Stalagmite TBR14 includes a 107mm calcitic
growth phase 230Th dated from 17070 ±40 to 15640 ±65 BP, which we interpret
to be the period of rainfall maximum over NE Brazil in association with HS-1.
Oxygen isotope analysis reveals a two-stepped structure to the HS-1 pluvial period:
starting with a 970-year period of δ18O values averaging -5‰ followed by an abrupt
2.5‰ drop between 16100 to 16080 BP (±20). We infer that rainfall amount increased
during this time, as supported by the modern day observation of anti-correlated
δ18O values and precipitation amount. A second step of the HS-1 growth phase
shows a gradual increase from -7‰ over 440 years followed by the termination of
stalagmite growth. Fluorescent banding was discovered throughout the stalagmite using
confocal laser fluorescence microscopy. If annual, band counts may add additional
constrains to the duration of the abrupt decrease in δ18O values observed at 16100
BP (±20). The two-stepped δ18O pattern observed in our stalagmite record may
correlate in detail with other low-latitude high-resolution records of HS-1 such as
the Hulu Cave record (Wang et al. 2001) from China, in which an abrupt (2.2)
weakening of the East Asian Monsoon at 16070 BP (±40) is followed by a 600
year recovery (decreasing) of δ18O values. The possible anti-phase relationship
between these two distant records is concurrent with the hypothesis of a southward
migrating ITCZ, and suggests rapid transmission of atmospheric signals during HS-1. |
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