Great Basin hydrology, paleoclimate, and connections with the North Atlantic: A speleothem stable isotope and trace element record from Lehman Caves, NV
- Permanent Link:
- Great Basin hydrology, paleoclimate, and connections with the North Atlantic: A speleothem stable isotope and trace element record from Lehman Caves, NV
- Series Title:
- Quaternary Science Reviews
- Cross, Mellissa
Broecker, Wallace S.
Shakun, Jeremy D.
Edwards, R. Lawrence
- Publication Date:
- Subjects / Keywords:
- Speleothem ( local )
Great Basin ( local )
Oxygen Isotopes ( local )
Carbon Isotopes ( local )
Trace Elements ( local )
Termination II ( local )
Heinrich Stadial ( local )
Effective Precipitation ( local )
- serial ( sobekcm )
- We present a record of speleothem stable isotope (Î´18O, Î´13C) and trace element (Mg/Ca, Sr/Ca) variations from Lehman Caves, Nevada for an interval of time (139â€“128 ka) that encompasses the penultimate glacial termination, Termination II (T-II). Additional growth phases provide data from about 123 ka, a time that correlates with Marine Isotope Stage (MIS) 5e, and about 84 ka and between 82 and 81 ka (MIS 5a). Chronologies from two new stalagmites are anchored by thirty-six uraniumâ€“thorium dates. We also present new trace element data from stalagmite LC-2, which has a previously published uraniumâ€“thorium chronology and stable isotope record of T-II (Shakun et al., 2011). Our T-II Î´18O record broadly replicates that of the Shakun et al. (2011) and Lachniet et al. (2014) records of this time, recording low values from 139 to 135 ka followed by an approximately 3.5â€° increase over an extended interval between 134 and 129 ka. This rise in Î´18O values occurs during Heinrich Stadial 11 and the associated Weak Monsoon Interval observed in Chinese caves; our record broadly follows the marine termination, rising boreal summer insolation, and the rise in atmospheric CO2. We infer that this shift results from temperature increase due to increasing atmospheric CO2 and potentially a change in moisture source or precipitation seasonality from greater influence of the North American Monsoon accompanying summer insolation increase. It is also plausible that the melting of the ice sheet itself may have contributed to both temperature and precipitation seasonality changes. Trace element ratios and Î´13C values are largely decoupled from Î´18O values, showing minimal variation between 139 and 130 ka, for the duration of the Chinese Weak Monsoon Interval. However, these values increase sharply between 130 and 128 ka, which we interpret as increased prior calcite precipitation driven by a transition from wet to dry conditions. This abrupt drying event coincides within dating uncertainties with the abrupt strengthening of the East Asian s
- Original Version:
- Quaternary Science Reviews, Vol. 127 (2015-11-01).
- Source Institution:
- University of South Florida Library
- Holding Location:
- University of South Florida
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- This object is protected by copyright, and is made available here for research and educational purposes. Permission to reuse, publish, or reproduce the object beyond the bounds of Fair Use or other exemptions to copyright law must be obtained from the copyright holder.
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