Williams, Berry L and Burns, Stephen J and Scroxton, Nick and Godfrey, Laurie R and Tiger, Benjamin H and Yellen, Brian and Dawson, Robin R and Faina, Peterson and McGee, David and Ranivoharimanana, Lovasoa (2024) A speleothem record of hydroclimate variability in northwestern Madagascar during the mid-late Holocene. The Holocene. ISSN 0959-6836

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Abstract

We present a continuous high-resolution precisely dated multiproxy record of hydroclimate variability at Anjohibe cave in northwestern Madagascar using speleothem AB13. The record spans from ~4484 y BP to ~2863 y BP. Stalagmite δ18O, δ13C and Sr/Ca ratios show very similar changes in hydroclimate. The mechanism controlling Sr/Ca changes, however, from prior calcite precipitation to degree of dolomite dissolution at about 4 ky BP. Our record is also in good agreement with previously published speleothem records from the same area. This agreement and multiproxy consensus indicate that AB13 provides a robust record of hydroclimate variability, including a continuous record of hydroclimate variability across the 4.2 ka event. This 4.2 ka event in Madagascar is marked by two distinct periods of drying between ~3900 y BP to 4300 y BP. A dry 4.2 ka event at this Southern Hemisphere site helps limit possible mechanisms for the event, indicating that a meridional shift to the south in the ITCZ is not responsible for the 4.2 ka event. In addition, the 4.2 ka event does not stand out as a unique dry period in our record. The longest and driest period of the record lasted ~300 years with peak dryness at ~3000 y BP. Our record differs significantly from a speleothem record from Rodrigues Island, located ~1800 km to the east of our study area in Madagascar suggesting different climatological controls on northwest Madagascar and more oceanic sites to the east.

Item Type:	Article
Keywords:	Anjohibe; hydroclimate; late-Holocene; Madagascar; mid-Holocene; paleoclimate; rainfall variability; speleothem; Sr/Ca trace element;
Academic Unit:	Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS
Item ID:	18202
Identification Number:	https://doi.org/10.1177/09596836231225725
Depositing User:	Corinne Voces
Date Deposited:	03 Apr 2024 08:23
Journal or Publication Title:	The Holocene
Publisher:	Sage
Refereed:	Yes
Funders:	The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by US National Science Foundation awards AGS-1702891/1702691, BCS-1750598 and EAR-1439559.
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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