Long-term changes in precipitation recorded by magnetic minerals in speleothems

Speleothems are important paleoclimate archives. Researchers typically compile measurements of stable isotopic ratios dated using high precision U-Th radiometric techniques to reconstruct regional and global climate. Magnetic material incorporated within speleothems can provide an independent means...

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Bibliographic Details
Published in:Geology (Boulder) 2015-07, Vol.43 (7), p.595-598
Main Authors: Bourne, Mark D, Feinberg, Joshua M, Strauss, Becky E, Hardt, Ben, Cheng, Hai, Rowe, Harold D, Springer, Gregory, Edwards, R. Lawrence
Format: Article
Language:English
Subjects:
absolute age
Allegheny Mountains
Appalachians
atmospheric precipitation
Buckeye Creek Cave
Caves
Cenozoic
Environmental conditions
isotope ratios
isotopes
magnetic minerals
magnetization
Minerals
Nanoparticles
North America
O-18/O-16
oxygen
Paleoclimate science
paleoclimatology
paleohydrology
paleomagnetism
Precipitation
Quaternary
Quaternary geology
remanent magnetization
solution features
speleothems
stable isotopes
Th/U
United States
upper Quaternary
West Virginia
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Summary:Speleothems are important paleoclimate archives. Researchers typically compile measurements of stable isotopic ratios dated using high precision U-Th radiometric techniques to reconstruct regional and global climate. Magnetic material incorporated within speleothems can provide an independent means of connecting large-scale climatic changes with their impact on more localized processes in soils overlying cave systems. Under certain environmental conditions, pedogenic processes can produce magnetite nanoparticles. Enhancement of pedogenic magnetite in soil profiles depends strongly on local precipitation. Pedogenic magnetite can be subsequently transferred via drip-waters into underlying cave-systems and incorporated into speleothems as they grow. Here, we employ high-resolution magnetic methods to analyze a well-dated stalagmite from Buckeye Creek Cave, West Virginia (USA), and find that changes in magnetite concentration follow both changes in stable isotopes measured in the same stalagmite and global climate proxies. We interpret the changes in magnetite concentration as reflecting variations in local pedogenic processes, controlled by changes in regional precipitation. This record demonstrates how magnetic measurements on speleothems can constrain interpretations of speleothem climate proxies.
ISSN:0091-7613
1943-2682
DOI:10.1130/G36695.1