ABSTRACT
Oxygen and carbon isotopic measurements of the total inorganic
carbon (TIC) fraction of sediments from Walker Lake (Nevada, USA)
were completed at a decadal-scale resolution spanning the last
~3000 years. On the basis of radiocarbon dating of the total
organic fraction of cored sediments, the late Holocene isotope
record recorded a relatively dry climate in Period LH-1 (1000 BC
to AD 800), a relatively wet climate punctuated by a few severe
droughts in Period LH-2 (AD 800 to 1900), and an anthropogenical
perturbation era (L14-h: 1900-2000). Relative high accumulation
rates in Period LH-2 (AD 800 to 1900) provided detailed
information on climatic and hydrologic variability in this region.
Coupled with the tree-ring-based Sacramento River flow record, the
radiocarbon-based age model was refined for the interval of AD 800
through 1900. A high-resolution (3.5 year per sample) TIC delta18O
record spanning the last 1200 years was generated to reflect
fluctuations in winter snowfall of the Sierra Nevada. This TIC
delta18O record shows two prolonged droughts that
occurred during the Medieval Warm Epoch, which are chronologically
well consistent with previous findings (STINF, 1994). Time series
analyses on the TIC delta18O and the Sacramento River
flow records reveal that interdecadal and centennial modes of
climate variability persisted over the last millennium. PDO-like
interdecadal oscillations that centered in the periods of 50-90 yr
were almost in phase with thermal fluctuations in ocean climate of
the California Current, suggesting that indedacadal climate
oscillations in the Sierra Nevada were intimately linked with the
Pacific dynamics. The underlying centennial to multicentennial
variability corresponding to the Medieval Warm Epoch and the
Little Ice Age comprise the major share of total variance. In
addition, the TIC delta18O record of Walker Lake is
visually well correlated with the polar ice-core-based cosmogenic
nuclide production and the Rice Lake Mg/Ca records. This suggests
that at least some centennial oscillations in winter precipitation
of the Sierra Nevada were associated with solar activity over the
last millennium.
Yuan, F., 2003. Late Holocene hydrologic and climatic variability
in the Walker Lake basin, Nevada and California.
Unpublished PhD dissertation, State University of New York
at Albany. 167 pp., +xii;
University at Albany Science Library call number: SCIENCE
MIC Film QC 869 Z899 2003 Y93
Copies of this PhD dissertation can be ordered
from Proquest UMI
Front matter (title,
table of contents, abstract, acknowledgements) - 0.5MB pdf
file
Figure pages (greyscale
and colour figures) - 2.3MB pdf file
Appendix
3 - Total inorganic carbon, total carbon, oxygen and carbon
isotopic compositions in Walker Lake cores