Joint 53rd South-Central/53rd North-Central/71st Rocky Mtn Section Meeting - 2019

Paper No. 31-2
Presentation Time: 8:20 AM


GAO, Yongli, Center for Water Research, Department of Geological Sciences, University of Texas at San Antonio, San Antonio, TX 78249, TAN, Liangcheng, Institute of Earth Environment, CAS, 97 Yanxiang Road, Xi'an, 710061, China, NISSEN, Julia, Department of Earth Sciences, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455, EDWARDS, R. Lawrence, Department of Earth Science, University of Minnesota, Minneapolis, MN 55455, CHENG, Hai, Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455 and ALEXANDER Jr., E. Calvin, Department of Earth & Environmental Sciences, University of Minnesota, 116 Church St. SE, 150 Tate Hall, Minneapolis, MN 55455

The hydroloclimate variability history in SE Minnesota during 3000-7269 yr BP is reconstructed by using high-resolution stalagmite records from Holy Grail Cave. The grey level variations show significant negative correlation with the Sr variations in the stalagmite, which indicates that both proxies were controlled by the hydroloclimate conditions outside the cave. More rainfall could enhance the vegetation development over the cave; wash more organic and detrital materials into the cave; and enrich grey level in stalagmite. In contrast, more rainfall could reduce the resident time of seepage water in the cave system and decrease the Sr concentration in stalagmite. In general, rainfall decreased in SE Minnesota from 7269 yr BP to 6560 yr BP. It remained dry between 6560 and 5890 yr BP and then rainfall gradually increased. There was a relative humid period during 5460-4530 yr BP followed by a sharp decrease of rainfall in SE Minnesota during 4530-4400 yr BP. Rainfall gradually increased after 4400 yr BP. This trend was similar to the δ13C record of another stalagmite from Spring Valley Caverns in the same region. Our records also suggest two notable centennial drought events occurred around 4350-4450 yr BP and 5830-6000 yr BP. Three wet periods were observed during 4950-5050 yr BP, 6440-6500, and 7050-7269 yr BP. Spectrum analysis demonstrates significant 22, 10, and 4.8-2.6 yr cycles in the grey level record, which may indicate solar activity and ENSO’s influences on hydroclimate variations in SE Minnesota during the mid-Holocene.