Presentation on theme: "Speleothem Micromorphology Enhances Interpretations of the Timing and Structure of the Mid-Holocene Warm Period Steven G. Driese Department of Geology,"— Presentation transcript:
1 Speleothem Micromorphology Enhances Interpretations of the Timing and Structure of the Mid-Holocene Warm PeriodSteven G. DrieseDepartment of Geology, Baylor UniversityZheng-Hua LiCenter for Space Plasma & Aeronomic Research, University of Alabama at HuntsvilleHai ChengDept. of Geology & Geophysics,University of MinnesotaStalagmite,Raccoon Mtn. TNNSF EAR to S.G.D.NSF EAR to Z.-H.L.South-central Section GSA 2013 Austin
2 PurposeInvestigate 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.
3 Distribution of Caves in the United States Chattanooga, TNIsotopically studied sitesFrom Culver et al., 1999
10 TopOnset of next wet phase obliterates annual bands, with angular unconformityThis 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
11 Speleothem δ13C values, ‰ PDB Pink = dryBlue= wet4,449 yr BP4,441 yr BPδ13C‰ PDBSr/Ca: Springer et al. 2008;Geophy. Research Letters(ThisStudy)Example 1: 100 yrsExample 2: 400 yrsU/Th ages, yrs. BP
12 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
13 Warm/Dry Hypsithermal/Altithermal event during Mid-Holocene: prolonged ENSO episodes, linkage between SW and SE USA?redrawn from
14 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 seasonalitySecond 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 phaseFUTURE APPLICATION TO OTHER MID-HOLOCENE INTERVALS WHERE ANNUAL LAMINAE PRESERVATION IS VISIBLE? TEXAS?
15 Soil Organic Matter (δ13C, ‰ PDB) Kocis, M.S. Thesis, 2011, Univ. of Tennessee-KnoxvilleN = 294N = 424 Mid-Holocene Warm/Dry Episodes ( ka BP)Driese et al., 2008,QuaternaryResearchXXXX
16 Refined Paleoclimate Reconstructions N.A. Mid-Holocene Thermal MaximumFrom Marcott et al. (2013) “A reconstruction of regional and global temperature for the past 11,300 years”: Science, v. 339, p , Figure 2(I).
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