STALAGMITE LAMINAE AS A CLIMATE PROXY: DECODING 1200 YEARS OF IBERIAN CLIMATE

The late Holocene, though a period of relatively small changes in temperature and precipitation patterns, has had dramatic hydroclimatic shifts, especially in regions like Iberia, a region identified as vulnerable to future drought by the most recent Intergovernmental Panel on Climate Change and others. It is critical to understand past climate variability in all parts of the world, but these identified hot spots require additional study. To accomplish this, it is important to develop highly-resolved, precisely-dated hydroclimate proxies from many sensitive locations.

Stalagmites from Buraca Gloriosa cave, western Portugal, preserve evidence of regional hydroclimate over the late Holocene with the most highly resolved records from approximately AD 800 to the present. Presented here are petrographic analyses of two stalagmites from BG cave as well as annual laminae records from these stalagmites. Characterizing the stratigraphy of stalagmites is an important task if stalagmites are to be used for paleoclimate reconstructions while variability in laminae thickness provide a record of growth rate that is related to past climate variability in Portugal. Laminae widths of these Portuguese stalagmites record wet and dry conditions with wider or narrower growth bands, respectively. Changes in calcite fabric from these two stalagmites along with laminae width records are used to infer past climate changes and better constrain future hydroclimate variability in this sensitive region.