Presentation on theme: "Steven G. Driese Department of Geology, Baylor University Zheng-Hua Li Center for Space Plasma & Aeronomic Research, University of Alabama at Huntsville."— Presentation transcript:
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 South-central Section GSA 2013 Austin Speleothem Micromorphology Enhances Interpretations of the Timing and Structure of the Mid-Holocene Warm Period NSF EAR to S.G.D. NSF EAR to Z.-H.L.
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 δ 13 C values of speleothem deposits with floodplain records, to ascertain Holocene paleoclimate history and events, such as mid- Holocene Altithermal event.
Chattanooga, TN Distribution of Caves in the United States From Culver et al., 1999 Isotopically studied sites
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 = mm/yr wetter drier
Time series of annual microbands mean = mm/yr wetter drier wetter
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 Top Onset of next wet phase obliterates annual bands, with angular unconformity
Speleothem δ 13 C values, PDB δ 13 C PDB Blue= wet Pink = dry (This Study) Sr/Ca: Springer et al. 2008; Geophy. Research Letters 4,449 yr BP 4,441 yr BP U/Th ages, yrs. BP Example 1: 100 yrs Example 2: 400 yrs
Nature of Annual Layers dark: spring + summer bright: fall + winter (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)
Warm/Dry Hypsithermal/Altithermal event during Mid-Holocene: prolonged ENSO episodes, linkage between SW and SE USA? redrawn from
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 (δ 13 C, PDB) 4 Mid-Holocene Warm/Dry Episodes ( ka BP) XXXX Kocis, M.S. Thesis, 2011, Univ. of Tennessee- Knoxville Driese et al., 2008, Quaternary Research N = 294 N = 42
Refined Paleoclimate Reconstructions From Marcott et al. (2013) A reconstruction of regional and global temperature for the past 11,300 years: Science, v. 339, p , Figure 2(I). N.A. Mid-Holocene Thermal Maximum