Speleothems as paleoclimate indicators in southeast Alaska

Speleothems are structures formed in a cave by the deposition of minerals from water and have proven to be useful paleoclimatic indicators in many parts of the world (Dorale et al. 1998; Wang et al. 2001; Fleitmann, 2009). Climatic signals can be captured in speleothems due to variations in δ18O and δ 13C isotopes, which are driven by changes in temperature/precipitation and vegetation cover, respectively. However, this technique has been seldom used in cave-rich regions of Southeast Alaska. Isotopic records from southeast Alaska using speleothems have the potential to vastly improve understanding of the timing and impact of paleoclimatic events during periods of relative warmth and glacial retreat, when permafrost melted and speleothem growth resumed. Parts of southeast Alaska were ice free during or shortly after the Last Glacial Maximum (LGM), offering an unprecedented opportunity to acquire temperature records during the last glacial/interglacial transition, including the last glacial maximum (LGM), Younger Dryas (YD) cold interval, Holocene thermal maximum, and subsequent neoglacial cooling. I will collect speleothems and produce isotopic records dated by 234U-230Th methods in order to improve regional and global climate chronologies and provide quantitative paleotemperature records for coastal southeastern Alaska during intervals of Late Pleistocene and Holocene climate change, including 16 – 14 kyr BP, when humans are proposed to have migrated through the area en route to the New World (Dillehay et al. 2008).