High resolution, U/Th dated (32,000 to 11,000 years), oxygen and carbon isotope proxy climate records from a stalagmite in Desoto Caverns, Alabama, USA

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dc.contributor Andrus, C. Fred T.
dc.contributor Tick, Geoffrey R.
dc.contributor Masterlark, Timothy
dc.contributor Kopaska-Merkel, David C.
dc.contributor.advisor Aharon, Paul
dc.contributor.author Lambert, William Joseph
dc.date.accessioned 2017-03-01T14:37:05Z
dc.date.available 2017-03-01T14:37:05Z
dc.date.issued 2010
dc.identifier.other u0015_0000001_0000471
dc.identifier.other Lambert_alatus_0004D_10547
dc.identifier.uri https://ir.ua.edu/handle/123456789/976
dc.description Electronic Thesis or Dissertation
dc.description.abstract This study addresses the question whether speleothems from DeSoto Caverns (Childersburg, AL) can serve as archives of paleoclimate conditions for the Southeast, USA. The focus of the study involves determining present-day controls of cave water δ^18 O and δ^13 C followed by interpretation of stalagmite δ^18 O and δ^13 C variability in comparison to climate events of the past. The monitoring program involved a 3-year study of cave waters and local rainfall (Tuscaloosa, AL) during years characterized by a significant trend from wet to dry conditions. Decreasing recharge of the cave aquifer was expressed as an interannual trend of declining drip flow rates, which was punctuated by seasonal oscillations due to varying rates of evapotranspiration. Amount-weighted mean monthly rainwater δ^18 O range from -1.5 to -8.3 /, show a mean seasonal amplitude of ~4 /, and exhibit an interannual trend toward ^18 O-enrichment that I interpret as being governed by global atmospheric circulation patterns. The cave's aquifer attenuates seasonal δ^18 O variability, records 20% of rainfall's interannual ^18 O-enrichment, and is biased toward winter rainfall δ^18 O. Cave waters display strong seasonal variability in dissolved inorganic carbon (DIC) and δ^13 C, which range from 0.2 to 6.0 mM and 2.7 to -12.9 / (VPDB), respectively. The data suggest the strongest seasonal controls are cave air ventilation/stagnation and varying CO_2 fluxes through the soil horizon and epikarst. δ^13 C of active speleothems imply the precipitating aragonite captures the seasonality observed in source dripwaters and time-series δ^13 C records of stalagmites carry the imprints of drip annual means entailing climate-driven δ^13 C seasonal biases. A fossil stalagmite provided a high-resolution proxy record of rainfall variability between 31.9 and 11.3 ka. I propose a more southerly polar jet stream (PJS) promoted increased winter rainfall amounts during cold phase events while warm phases result in a higher PJS position and decreased winter rainfall. The Younger Dryas was characterized by a dramatic change in the PJS path as warm air from the Gulf of Mexico infiltrated deep into the continent's interior and substantially decreased winter rainfall. Establishment of near modern climate conditions greatly enhanced deposition rates before changes in flow paths through the epikarst prevented stalagmite deposition since 11.3 ka.
dc.format.extent 249 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Geology
dc.subject.other Climate Change
dc.subject.other Paleoclimate Science
dc.title High resolution, U/Th dated (32,000 to 11,000 years), oxygen and carbon isotope proxy climate records from a stalagmite in Desoto Caverns, Alabama, USA
dc.type thesis
dc.type text
etdms.degree.department University of Alabama. Dept. of Geological Sciencess
etdms.degree.discipline Geology
etdms.degree.grantor The University of Alabama
etdms.degree.level doctoral
etdms.degree.name Ph.D.

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