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Showing 1 to 20 of 76 for “"cosmogenic"”.
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Cosmogenic 14 CO as tracer for atmospheric chemistry and transport
… CH3CCl3 and CFCl3. Next, uncertainties in the cosmogenic 14C source distribution and their implications for the 14CO application are studied. The influence of the variable solar activity on cosmogenic 14C production and atmospheric 14CO is investigated, as is the effect of solar proton event …
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Extraction and measurement of cosmogenic in situ 14C from quartz
… short half-life of 5730 years, provides a unique cosmogenic nuclide tool for the measurement of rapid erosion rates (>10-3 cm yr-1) and events occurring over the past 25,000 yr (Lal, 1991). Furthermore, recent advances in 14C dating by AMS have provided the opportunity to measure the very small …
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Surface exposure geochronology using cosmogenic nuclides : applications in Antarctic glacial geology
Cosmogenic 3He, 26A1, and 10Be have been measured in a variety of Antarctic glacial deposits in the McMurdo Sound-Dry Valleys region. The goals of this project were to provide age constraints for Antarctic glacial events, to investigate production mechanisms of 3He, lOBe, and 26 A1 in terrestrial …
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Cosmogenic dating of fluvial terraces in the Sorbas Basin, SE Spain
… terraces. This study applies the technique of cosmogenic exposure dating to a fluvial staircase, for the first time, in the Sorbas Basin, SE Spain. Cosmogenic exposure dating allows the timing of abandonment of the fluvial terraces to be calculated therefore recording periods of incision. …
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Surface exposure geochronology using cosmogenic nuclides : applications in Antarctic glacial geology
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and the Woods Hole Oceanographic Institution, 1994.
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Dating of alluvial fans from NW Argentina using cosmogenic nuclides and optically stimulated luminescence technique
… (OSL/IRSL) dating and one depth profile for cosmogenic radionuclide dating (10Be) were collected in the Santa Maria Valley in NW Argentina, where the exceptional preservation of several generations of alluvial fans allow exploring the external forcing conditions that led to repeated cycles of …
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Single grain detrital cosmogenic Ne-21 analysis: a new tool to study long-term landscape evolution
Cosmogenic nuclide concentrations in alluvial sediment are now routinely used to estimate time and space-averaged catchment-wide denudation rates, but have the potential to offer considerably more. This is because each grain leaving a catchment has a potentially unique history of erosion, transport …
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A new extraction technique and production rate estimate for in situ cosmogenic carbon-14 in quartz
The potential utility of in situ cosmogenic ¹⁴C (in situ ¹⁴C) in surficial process studies is widely recognized, yet a reliable means of isolating it has proved difficult to develop. Here we present a new method for isolating in situ ¹⁴C in quartz that yields more precise estimates of production …
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Cosmogenic ³²P and ³³P in the atmosphere and aligotrophic ocean and applications to the study of phosphorus cycling
Cosmogeruc P-32 (14.28 days) and P-33 (25.3 days) are powerful tracers of upper ocean P cycling, when coupled with time-series of the atmospheric sources. A method was developed to determine the low-level beta activities in rainwater and plankton. The wet deposition rates of P-32 and P-33 were …
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Landscape evolution and equilibrium in Southern Africa : insights from cosmogenic noble gases in Karoo dolerites and geospatial analyses
Southern Africa’s landscape is characterised by a high plateau (elevation > 1,000 m) bound by escarpments and extensional continental margins, and the region has been influential in the development of geomorphological theory. However, the evolution of this landscape in response to tectonic and …
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Cosmogenic 32P and 33P in the atmosphere and aligotrophic ocean and applications to the study of phosphorus cycling
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1993.
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Terrestrial cosmogenic nuclide dating applied in glacial stratigraphy and transportation studies on a greenfield exploration project in Kaarestunturi, Finnish Lapland
… Glacier Dynamic (GD) mapping and Terrestrial Cosmogenic Nuclide (TCN) dating. The local interpretation is set in a regional glacial history framework that is based on wide scaled GD mapping and existing literature. Kaarestunturi is incorporated in multiple regional glacial studies, but no …
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Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE
… This study presents the first in situ-produced cosmogenic 10Be inventories determined for quartz from catchment sediments and bedrock surfaces within the coastal Cape Mountains, with which to quantify denudation rates, exposure ages and the recent geomorphic evolution of these Cape Mountains. …
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THE PACE AND TIMING OF CHANGING LANDSCAPES AS VIEWED THROUGH COSMOGENIC RADIONUCLIDES: SYNTHETIC AND REAL EXAMPLES FROM THE CENTRAL ANDES AND AMAZONIA
<p>In the past three decades, the use of cosmogenic radionuclides revolutionized research in geomorphology. Cosmogenic radionuclides, such as 10Be and 26Al, accumulate within quartz crystals at a relatively well-constrained rate due to the bombardment of the Earth’s atmosphere by cosmic rays. Since …
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Landscape evolution and preservation of ice over one million years old quantified with cosmogenic nuclides 26Al, 10Be, and 21Ne, Ong Valley, Antarctica
… advances and stagnations of the Argosy Glacier. Cosmogenic exposure age dating of these tills provides ages, ice sublimation rates and regolith erosion rates that support the antiquity of the ice below. </p><p> The oldest ice on Earth has an undisputed age of 800 Kya and is at the bottom of large …
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Cenozoic tectonic and geomorphic evolution of the Red River Region, Yunnan Province, China
… during growth of the southeast plateau margin. Cosmogenic ²⁶A1 and ¹⁰Be basin-wide erosion rate and burial ages indicate a background incision rate of [approximately] 0.05 to 0.10 mm/a, lower than the long-term incision rate minimum of [approximately] 0.26 mm/a. Cosmogenically-determined …
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Deep-seated bedrock landsliding in Grand Canyon's Surprise Valley area
… cross-sections, strath terrace heights, and cosmogenic burial dating of river deposits buried by landslides. Mapping shows failures involving ~1000 m Paleozoic section localized within basal shale detachments, dammed and diverted the Colorado River and local tributaries, and forced the …
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Beryllium-10 derived erosion rates from the Hangay Mountains, Mongolia: landscape evolution in a periglacially-dominated continental interior
Terrestrial cosmogenic nuclides such as beryllium-10 have recently been used as a way to determine basin-average erosion rates around the world. These erosion rates are useful to geomorphologists investigating landscape evolution. The Hangay Mountains in Mongolia are a prime location to use …
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Investigating the Distribution and Source(s) of Lunar Volatiles
… wind components, with only minor amounts of cosmogenic neon being released at the highest temperature steps. In mare basalts, noble gases are a mixture of trapped, radiogenic, and cosmogenic components (from which cosmogenic production rates can be calculated and exposure ages for previously …
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Tectonic-Climate Interactions And Glacial History Within The Chugach And Kenai Mountains, Alaska
… utilized low temperature thermochronometry and cosmogenic dating to constrain the spatial and temporal distribution of exhumation and glacial history in order to characterize the net effect of glaciers on an orogen that experiences slow rock uplift. We constrain the spatial distribution of …
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