Speleothem Micromorphology Enhances Interpretations of the Timing and Structure of the Mid-Holocene Warm Period Steven G. Driese Department of Geology, Baylor University Zheng-Hua Li Center for Space Plasma & Aeronomic Research, University of Alabama at Huntsville Hai Cheng Dept. of Geology & Geophysics, University of Minnesota Stalagmite, Raccoon Mtn. TN NSF EAR-0823131 to S.G.D. NSF EAR- 0822824 to Z.-H.L. South-central Section GSA 2013 Austin

Purpose Investigate the feasibility of using speleothems to reconstruct a high-resolution paleoclimate history in southeastern US. Combine UV fluorescence micromorphology with U-Th chronology to establish annual records for speleothem. Compare δ13C values of speleothem deposits with floodplain records, to ascertain Holocene paleoclimate history and events, such as mid-Holocene Altithermal event.

Distribution of Caves in the United States Chattanooga, TN Isotopically studied sites From Culver et al., 1999

Raccoon Mountain Cave

C, O isotopes in the cave system Temperature / Water effect Vegetation / Atmosphere

Sample analyzed for this study 15 cm

Time series of annual microbands mean = 0.038 mm/yr wetter drier

Time series of annual microbands wetter wetter mean = 0.027 mm/yr wetter wetter drier drier drier

Base

Top Onset of next wet phase obliterates annual bands, with angular unconformity This major dissolution surface mantled by terra rossa material is tentatively dated as pre-7.6 ka, so we have 400 years of record going into the onset of the mid-Holocene warming and drying

Speleothem δ13C values, ‰ PDB Pink = dry Blue= wet 4,449 yr BP 4,441 yr BP δ13C‰ PDB Sr/Ca: Springer et al. 2008; Geophy. Research Letters (This Study) Example 1: 100 yrs Example 2: 400 yrs U/Th ages, yrs. BP

Nature of Annual Layers dark: spring + summer (a) Shihua Cave, Beijing; (b) Stalagmite ER-77, Ernesto Cave, Italy; (c) Flowstone WM1, Wilder Mann Cave, Austria, Meyer et al. (2009): (in Fairchild & Baker, 2012) bright: fall + winter

Warm/Dry Hypsithermal/Altithermal event during Mid-Holocene: prolonged ENSO episodes, linkage between SW and SE USA? redrawn from http://www.cdc.noaa.gov/ENSO/ 

Summary: Proxy Records of Abrupt Holocene Climate and Environmental Change First example (100 year record) captures the transition from a 5.4 ka dry phase into wet phase, with very distinct seasonality Second example (400 year record) captures the transition from late Pleistocene to early Holocene, dissolution unconformity (with terra rossa) into first post-7.6 ka dry phase FUTURE APPLICATION TO OTHER MID-HOLOCENE INTERVALS WHERE ANNUAL LAMINAE PRESERVATION IS VISIBLE? TEXAS?

Soil Organic Matter (δ13C, ‰ PDB) Kocis, M.S. Thesis, 2011, Univ. of Tennessee-Knoxville N = 294 N = 42 4 Mid-Holocene Warm/Dry Episodes (4.2-6.6 ka BP) Driese et al., 2008, Quaternary Research X X X X

Refined Paleoclimate Reconstructions N.A. Mid-Holocene Thermal Maximum From Marcott et al. (2013) “A reconstruction of regional and global temperature for the past 11,300 years”: Science, v. 339, p. 1198-1201, Figure 2(I).