Limitations of absolute age constraints for the Quaternary morainal record in the Eastern Sierra Nevada, California from detailed stratigraphic relationships of the Casa Diablo till Margie B. DeRose Martin J. Kennedy Department of Earth Sciences University of California, Riverside
High Resolution Climate Records North Atlantic δ 18 O Records Marine sediment cores Greenland ice cores
North Atlantic Marine Sediment WARM COLD 3 Million-year δ 18 O record Raymo (1994)
Greenland Ice 1 +120 ka δ 18 O record COLD WARM Steffensen, et al. (2008)
Greenland Ice Core WARM COLD Altabet, et al. (2002)
Rapid Changes GISP2 WARM COLD Alley, et al. 1993
Sierra Nevada Sierra Nevada http://geon.unavco.org/unavco/lib/images/california_3d_relief_topography_oblique.jpg
http://www.goes-arch.noaa.gov/cgi-bin/post-archive Sierra Nevada
North Atlantic & Greenland ice records Relevance to the Sierran climate record?
North Atlantic & Greenland ice records Relevance to the Sierran climate record? Frequency of abrupt change recorded in the Sierra?
North Atlantic & Greenland ice records Relevance to the Sierran climate record? Frequency of abrupt change recorded in the Sierra? Cyclicity and timing of events?
North Atlantic & Greenland ice records Relevance to the Sierran climate record? Frequency of abrupt change recorded in the Sierra? Cyclicity and timing of events? In phase with the North Atlantic records?
North Atlantic & Greenland ice records Relevance to the Sierran climate record? Frequency of abrupt change recorded in the Sierra? Cyclicity and timing of events? In phase with the North Atlantic records? Stable or unstable?
WARM COLD Santa Barbara Basin ODP Site 893 (Robert, 2004)
Death Valley (Yang, et al., 2005)
Mono Lake (Benson et al., 1998)
Mono Lake Sierra Nevada Death Valley Santa Barbara Basin ODP 893 http://fermi.jhuapl. edu/states/maps_ bw/ca_bw.gif
Sierran Climate Record Frequency of ice advance in Sierra Connection with Northern Hemisphere climate Moraines Direct record of glacial advance & retreat
Convict Lake Photo of Convict Lake & recessional moraines (Google Earth Image, 2008)
(Google Earth Image, 2008) Pine Creek
Sierran Climate Record Chronology for morainal record timing, magnitude, & frequency Age control 14 C Limited to ~40,000 yr and younger (Walker, 2005) Cosmogenic Potential error of at least 20% (Walker, 2005) Need absolute age control
Mammoth Lakes www.mapquest.com
Glacial Geologic Map of the Long Valley Caldera (Bailey, 1989)
Volcanic Geologic Map of the Long Valley Caldera (Bailey, 1989)
Absolute Age Constraints Stratigraphic Relationships Only 2 absolute age constraints Sherwin till Casa Diablo till Chronology of Sierran glacial record
Sherwin Till Bishop Tuff 759 ± 2ka 40 K/ 40 Ar (Sarna-Wojcicki et al., 2000) Bishop Tuff Sherwin Till HWY 395
Casa Diablo Till Casa Diablo Till Map: Bailey (1989) miles
Casa Diablo Till Map: Bailey (1989) miles Lower Basalt 126 ± 25 ka 40 K/ 40 Ar (Bailey, 1976)
Casa Diablo Till Upper Basalt 62 ± 13 ka 40 K/ 40 Ar (Bailey, 1976) Map: Bailey (1989) miles
Detailed Mapping Casa Diablo till Address bounding age relationships Show relative ages Relation to volcanics Any new relationships
Preliminary Results Lack of evidence for the upper bounding basalt flow No younger age control New undocumented relationships Potential additional age constraints Improve resolution of the Sierran climate record
Conclusions Void in established chronology for the Sierran glacial record Correlation with broader records Additional age controls may exist Clear need for further detailed studies Improve chronology Hemispheric teleconnections
Project Support Valentine Eastern Sierra Reserve Graduate Student Research Grant 2008 White Mountain Research Station Graduate Student Minigrant 2008 John Dunham Field Fellowship, Department of Earth Sciences, University of California, Riverside 2008