department of geology, baylor university,

STEVE DRIESE1, Zheng-Hua LI2, Hai CHENG3, Gary STINCHCOMB1, Jim KOCIS4, Sally HORN5, and Mathew BOEHM5

(1) Department of Geology, Baylor University, (2) Center for Space Plasma & Aeronomic Research, University of Alabama at Huntsville (3) Department of Geology and Geophysics, University of Minnesota (4) Department of Geosciences, University of Massachusetts, and (5) Department of Geography, University of Tennessee, Knoxville

Savannah Creek (SC), SE Tenn., (Driese et al., 2008, Quaternary Research)

Lower Tenn. River Valley basin (Kocis, M.S. Thesis, 2011; (MS, JA, HA)ms. in prep.)

Raccoon Mtn.Cave (RMC)speleothem (Li & Driese, Sedimentology,accepted; ms. in prep.)

RMCSC

Savannah Creek site near Ooltewah, TN; Driese et al., 2008

Site MS along Tennessee River, Marshall County, AL; Kocis, unpub. MS Thesis, UT-Knoxville , 2011

Normalized δ13CSOM values: values were subtracted from the average recent (last1000 years) δ13CSOM value for each floodplain section (e.g., Nordt et al., 2008)

4 Mid-Holocene Warm/Dry Episodes (4.2-6.6 ka BP)

X X X X

Kocis, M.S. Thesis, 2011

Driese et al., 2008, QR

N = 294

N = 42

UV Fluorescence (UVf) of ultra-polished thin sections (@Baylor U.)

U/Th dating of speleothem (@U. Minnesota)

Micro-drilling of powders for δ13C and δ18O analyses (@U. Tennessee-Knoxville and Alabama-Huntsville)

Pollen extraction (@U. Tennessee-Knoxville)

δ13C

‰ P

DB

Blue= wet

Pink = dry

(ThisStudy)

Sr/Ca: Springer

et al. 2008;

Geophy. Research

Letters

4,449 yr BP

4,441 yr BP

U/Th ages, BP

pre-7500 yr BP wet period

A B

PPL XPL

7.5ka BP major dissolution surface with 0.5-1 mm thick terra rossa deposits

Micro-banding is invisible using ordinary microscopy but very apparent with UVf!

4870 yr BP dissolution surface (wet)

organics = “bright”

Ann

ual g

row

th b

ands

, se

ason

ality

rec

ord?

drier

wetter

drier

mean = 0.038 mm/yrwetter

drier

Dry periods (7400~68907400~6890, 5950~53405950~5340, and 4870~40504870~4050 yr BP): 10-100 μm thick, micro-banded (bright/dark UVf) intervals, which may represent annual precipitation bands

Wet periods (13,000-7,50013,000-7,500, 6890-59596890-5959, and 5340-48705340-4870 yr BP): Disconformity surfaces, identified by calcite crystal corrosion and truncation, associated non-UVf capped by bright UVf, and perched terra rossa (clastic) material; Coarse, sector-zoned UVf crystals with wide bands?

Castanea Quercus

PinusFraxinus

(Research of Matthew Valente, UT-Knoxville)

interval at 87-83 cm depth in new Anderson Pond core (>charcoal age at 80-81 cm depth, 6242-5997 yr BP)

Delcourt (1979) Ecol. Monographs

Do desiccation intervals with illuviated clays & high charcoal in new Anderson Pond core correspond to dry periods recorded in Raccoon Mountain Cave speleothem?)

Mid-Holocene warm/dry interval, 5000-8000 based on > charcoal

Pollen from Delcourt (1979)Joanne Ballard point-counts

Speleothem UVf micromorphology very useful in detecting “hidden” microfabrics (e.g., micro-dissolution surfaces, micro-banding) not visible in PPL or XPL

Chronol.-constrained speleothems, combined w/micro-imaging/sampling for δ13C and δ18O analyses → detailed interpretations of timing of wet-dry cycles, ppt. seasonality

Speleothems can provide better time resolution of climate changes than floodplains/buried soils (ideally use both)

NSF EAR 0822824 to Li and HornNSF EAR 0823131 to DrieseCharcoal work by Joanne BallardPollen work by Matthew ValenteUT-Knoxville Initiative

for Quaternary Paleoclimate Research (IQPR)