Filters: Tags: radiocarbon (X) > partyWithName: U.S. Geological Survey (X)
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The Weldona 7.5' quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The South Platte River, originating high in the Colorado Rocky Mountains, has played a major role in shaping surficial geology in the map area, which is several tens of kilometers downstream from where headwater tributaries join the river. Recurrent glaciation (and deglaciation) of basin headwaters has affected river discharge...
The Fort Morgan 7.5' quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the late Pliocene to the present. The South Platte River, originating high in the Colorado Rocky Mountains, has played a major role in shaping surficial geology in the map area, which is several tens of kilometers downstream from where headwater tributaries join the river. Recurrent glaciation (and deglaciation) of basin headwaters has affected river discharge...
Fumarole gas geochemistry and tree-ring radiocarbon data at Mammoth Mountain, California (1989-2016)
Mammoth Mountain is a dacitic dome complex located on the southwestern rim of Long Valley Caldera, California. Mammoth Mountain has exhibited unrest over the past ~30 years, characterized by seismicity over a broad range of depths, elevated 3He/4He ratios in fumarolic gas and large-scale diffuse CO2 emissions. Monitoring of this unrest has included collection of fumarole gas samples for geochemical analysis and tree cores for radiocarbon analysis of annual growth rings. This report updates the long-term geochemical record at Mammoth Mountain, compiling the chemical and isotopic (d13C-CO2, 3He/4He) compositions of 59 gas samples collected from Mammoth Mountain fumarole from 1998 to 2016. In addition, we report radiocarbon...
Categories: Data;
Tags: Geochemistry,
Mammoth Lakes,
Mammoth Mountain,
Mono County,
USGS Science Data Catalog (SDC),
In conjunction with geologic mapping of four 7.5′ quadrangles along the South Platte River corridor in northeastern Colorado (Masters, Orchard, Weldona, and Fort Morgan), geochronology samples were collected and analyzed using optically stimulated luminescence (OSL), radiocarbon (14C), or U-series methods to provide age control for mapping units. This section of river corridor is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The South Platte River originates high in the Colorado Rocky Mountains and recurrent glaciation of basin headwaters has affected river discharge and sediment...
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