CHANGES OF MOSITURE AVAILABILITY DURING MARINE ISOTOPE STAGES 5-6 BASED ON TWO SPELEOTHEM RECORDS FROM KENTUCKY, NORTH AMERICA

Based on their abundant proxies, precise chronology, and wide distribution, speleothems have been considered as one of the most important natural archives of past climate change. However, compared to numerous paleoclimate research using speleothems on other continents (such as Asia, Europe, and Australia), relatively few speleothem-based paleoclimate records exist for North America (NA). Furthermore, climate change in NA is closely connected to the evolution and relative influences of the Laurentide Ice Sheet and North Atlantic circulation (Springer et al., 2008, 2014). Therefore, detailed paleoclimate records in NA yield more advantages for understanding and refining how Ice Age climates change and what factors control Ice Age cycles (Cruz et al., 2005; Cheng et al., 2009).

Here, based on forty-five precise U-Th age data covering 160-80 kyr BP, with typical error of ±0.1−0.8 kyr, a high-resolution composite moisture availability chronology has been constructed using Sr/Ca and growth rates from two stalagmites (SV4 and SV5) collected from Sloan Valley Cave, Kentucky. Barring the growth hiatus from 106-125kyr BP, it can be observed that Sr/Ca and growth rate results define a similar pattern to other NA moisture records (Springer et al., 2014; Bourne et al., 2015). The Sr/Ca record, with multi-decadal resolution, roughly follows the variation of solar insolation and global sea level which increased at ~131±0.6 kyr BP and peaked at ~125±0.66 kyr BP, concurrent with the hiatus. The SV growth rate results also reveal the linkage with insolation and sea level. A close connection between the moisture availability variation in NA and solar insolation and ice sheet change is demonstrated.