Publications
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Sediment geochemical records of productivity and oxygen depletion along the margin of western North America during the past 60,000 years: Teleconnections with Greenland Ice and the Cariaco Basin Sediment geochemical records of productivity and oxygen depletion along the margin of western North America during the past 60,000 years: Teleconnections with Greenland Ice and the Cariaco Basin
Many sediment records from the margins of the Californias (Alta and Baja) collected in water depths between 60 and 1200 m contain anoxic intervals (laminated sediments) that can be correlated with interstadial intervals as defined by the oxygen-isotope composition of Greenland ice (Dansgaard–Oeschger, D–O, cycles). These intervals include all or parts of Oxygen Isotope Stage 3 (OIS3; 60...
Authors
Walter E. Dean
Geology Geology
This map shows the ages and types of rocks that lie at or near the land surface throughout the United States. It does not show surficial materials such as soil and glacial deposits, except where Quartenary sedimentary materials cover extensive areas and obscure underlying bedrock materials. The map is a generalization and simplification of the "Geologic Map of North America," published...
Authors
John C. Reed, Charles A. Bush
Loess records: North America Loess records: North America
No abstract available.
Authors
H.M. Roberts, D.R. Muhs, E. Arthur Bettis
Global Data Toolset (GDT) Global Data Toolset (GDT)
According to the United Nations Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) approximately 60 percent of the data contained in the World Database on Protected Areas (WDPA) has missing or incomplete boundary information. As a result, global analyses based on the WDPA can be inaccurate, and professionals responsible for natural resource planning and priority...
Authors
Jill J. Cress, Jodi L. Riegle
Paleoecology reconstruction from trapped gases in a fulgurite from the late Pleistocene of the Libyan Desert Paleoecology reconstruction from trapped gases in a fulgurite from the late Pleistocene of the Libyan Desert
When lightning strikes the ground, it heats, melts, and fuses the sand in soils to form glass tubes known as fulgurites. We report here the composition of CO2, CO, and NO contained within the glassy bubbles of a fulgurite from the Libyan Desert. The results show that the fulgurite formed when the ground contained 0.1 wt% organic carbon with a C/N ratio of 10-15 and a ??13C of -13.96
Authors
Gonzalez R. Navarro, S. A. Mahan, A.K. Singhvi, R. Navarro-Aceves, J.-L. Rajot, C.P. McKay, P. Coll, F. Raulin
Late quaternary paleoseismology of the southern Steens fault zone, northern Nevada Late quaternary paleoseismology of the southern Steens fault zone, northern Nevada
The 192-km-long Steens fault zone is the most prominent normal fault system in the northern Basin and Range province of western North America. We use trench mapping and radiometric dating to estimate displacements and timing of the last three surface-rupturing earthquakes (E1-E3) on the southern part of the fault south of Denio, Nevada. Coseismic displacements range from 1.1 to 2.2 ?? 0...
Authors
S. F. Personius, A. J. Crone, M. N. Machette, S. A. Mahan, J.B. Kyung, H. Cisneros, D. J. Lidke
Upper Neogene tephrochronologic correlations in the northern Rio Grande Rift, New Mexico and southern Colorado Upper Neogene tephrochronologic correlations in the northern Rio Grande Rift, New Mexico and southern Colorado
No abstract available.
Authors
Janet L. Slate, Andrei M. Sarna-Wojcicki, Elmira Wan, Daniel Koning, Sean D. Connell, David P. Dethier, David B. Wahl, Michael Perkins
Dust emission from wet and dry playas in the Mojave Desert, USA Dust emission from wet and dry playas in the Mojave Desert, USA
The interactions between playa hydrology and playa-surface sediments are important factors that control the type and amount of dust emitted from playas as a result of wind erosion. The production of evaporite minerals during evaporative loss of near-surface ground water results in both the creation and maintenance of several centimeters or more of loose sediment on and near the surfaces...
Authors
Richard L. Reynolds, James C. Yount, Marith C. Reheis, Harland L. Goldstein, Pat F. Chavez, Robert E. Fulton, John W. Whitney, Christopher C. Fuller, Richard M. Forester
An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils
There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence...
Authors
S. A. Mahan, D.J. Brown
Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front
Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but...
Authors
M.F. Sohn, S. A. Mahan, J.R. Knott, D.D. Bowman
Late Quaternary stratigraphy and luminescence geochronology of the northeastern Mojave Desert Late Quaternary stratigraphy and luminescence geochronology of the northeastern Mojave Desert
The chronology of the Holocene and late Pleistocene deposits of the northeastern Mojave Desert have been largely obtained using radiocarbon ages. Our study refines and extends this framework using optically stimulated luminescence (OSL) to date deposits from Valjean Valley, Silurian Lake Playa, Red Pass, and California Valley. Of particular interest are eolian fine silts incorporated in...
Authors
S. A. Mahan, D. M. Miller, C.M. Menges, J. C. Yount