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Title: Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada

Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. In this paper, we compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of boulders on moraines of the younger advance are between 15 and 30 ka and may be associated with marine oxygen isotope stage (MIS) 2. At Woodfords, TCN ages of boulders on the moraine of the older advance are younger than ~ 60 ka and possibly formed during MIS 4, whereas boulders on the correlative outwash surface show ages approaching 140 ka (~ MIS 6). The TCN ages of boulders on older glacial moraine at Woodfords thus appear to severely underestimate the true age of the glacial advance responsible for the deposit. The same is possibly true at Lamoille where clasts sampled from the moraine of the oldest advance have ages ranging between 20 and 40 ka with a single outlier age of ~ 80 ka. The underestimations are attributed to the degradation and denudationmore » of older moraine crests. Noting that boulder ages on the older advances at each site overlap significantly with MIS 2. Finally, we speculate that erosion of the older moraines has been episodic, with a pulse of denudation accompanying the inception of MIS 2 glaciation.« less
Authors:
 [1] ;  [2] ;  [3] ; ORCiD logo [4] ;  [4] ;  [5]
  1. Univ. of Nevada, Reno, NV (United States). Center for Neotectonic Studies
  2. United States Geological Survey, Golden, CO (United States)
  3. Purdue Univ., West Lafayette, IN (United States). Dept. of Physics
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Inst. of Geophysics and Planetary Physics
  5. Univ. of Cincinnati, OH (United States)
Publication Date:
Report Number(s):
UCRL-JRNL-218878
Journal ID: ISSN 0169-555X
Grant/Contract Number:
AC52-07NA27344; G15AP00088; G14AP00048
Type:
Accepted Manuscript
Journal Name:
Geomorphology
Additional Journal Information:
Journal Volume: 268; Journal ID: ISSN 0169-555X
Publisher:
Elsevier
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); United States Geological Survey, Golden, CO (United States)
Sponsoring Org:
USDOE; United States Geological Survey (USGS)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; geomorphology; moraines; cosmogenic dating; Sierra Nevada; Ruby Mountains-East Humboldt Range
OSTI Identifier:
1438659

Wesnousky, Steven G., Briggs, Richard W., Caffee, Marc W., Ryerson, F. J., Finkel, Robert C., and Owen, Lewis A.. Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada. United States: N. p., Web. doi:10.1016/j.geomorph.2016.04.027.
Wesnousky, Steven G., Briggs, Richard W., Caffee, Marc W., Ryerson, F. J., Finkel, Robert C., & Owen, Lewis A.. Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada. United States. doi:10.1016/j.geomorph.2016.04.027.
Wesnousky, Steven G., Briggs, Richard W., Caffee, Marc W., Ryerson, F. J., Finkel, Robert C., and Owen, Lewis A.. 2016. "Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada". United States. doi:10.1016/j.geomorph.2016.04.027. https://www.osti.gov/servlets/purl/1438659.
@article{osti_1438659,
title = {Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada},
author = {Wesnousky, Steven G. and Briggs, Richard W. and Caffee, Marc W. and Ryerson, F. J. and Finkel, Robert C. and Owen, Lewis A.},
abstractNote = {Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. In this paper, we compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of boulders on moraines of the younger advance are between 15 and 30 ka and may be associated with marine oxygen isotope stage (MIS) 2. At Woodfords, TCN ages of boulders on the moraine of the older advance are younger than ~ 60 ka and possibly formed during MIS 4, whereas boulders on the correlative outwash surface show ages approaching 140 ka (~ MIS 6). The TCN ages of boulders on older glacial moraine at Woodfords thus appear to severely underestimate the true age of the glacial advance responsible for the deposit. The same is possibly true at Lamoille where clasts sampled from the moraine of the oldest advance have ages ranging between 20 and 40 ka with a single outlier age of ~ 80 ka. The underestimations are attributed to the degradation and denudation of older moraine crests. Noting that boulder ages on the older advances at each site overlap significantly with MIS 2. Finally, we speculate that erosion of the older moraines has been episodic, with a pulse of denudation accompanying the inception of MIS 2 glaciation.},
doi = {10.1016/j.geomorph.2016.04.027},
journal = {Geomorphology},
number = ,
volume = 268,
place = {United States},
year = {2016},
month = {5}
}