Now showing items 1-10 of 68
Elastic wave speeds and moduli in polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate
(American Geophysical Union, 2009-02-27)
We used ultrasonic pulse transmission to measure compressional, P, and shear, S, wave speeds in laboratory-formed polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate. From the wave speed's linear ...
Correction to “Elastic wave speeds and moduli in polycrystalline ice Ih, sI methane hydrate, and sII methane-ethane hydrate”
(American Geophysical Union, 2009-04-10)
Duration and severity of Medieval drought in the Lake Tahoe Basin
(Elsevier B.V., 2001-09-16)
Droughts in the western U.S. in the past 200 years are small compared to several megadroughts that occurred during Medieval times. We reconstruct duration and magnitude of extreme droughts in the northern Sierra Nevada ...
Modeling sulfate reduction in methane hydrate-bearing continental margin sediments : does a sulfate-methane transition require anaerobic oxidation of methane?
(American Geophysical Union, 2011-07-12)
The sulfate-methane transition (SMT), a biogeochemical zone where sulfate and methane are metabolized, is commonly observed at shallow depths (1–30 mbsf) in methane-bearing marine sediments. Two processes consume sulfate ...
Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions
(American Geophysical Union, 2011-04-20)
The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the ...
Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand
Sediments from the Porangahau ridge, located off the northeastern coast of New Zealand, were studied to describe bacterial community structure in conjunction with differing biogeochemical regimes across the ridge. Low ...
Elevated gas hydrate saturation within silt and silty clay sediments in the Shenhu area, South China Sea
(American Geophysical Union, 2011-05-25)
Gas hydrate saturations were estimated using five different methods in silt and silty clay foraminiferous sediments from drill hole SH2 in the South China Sea. Gas hydrate saturations derived from observed pore water ...
More than a century of bathymetric observations and present-day shallow sediment characterization in Belfast Bay, Maine, USA: implications for pockmark field longevity
Mechanisms and timescales responsible for pockmark formation and maintenance remain uncertain, especially in areas lacking extensive thermogenic fluid deposits (e.g., previously glaciated estuaries). This study characterizes ...
Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean : evidence for accelerated porosity reduction?
(Oxford University Press, 2016-01)
The Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is ...
Volume change associated with formation and dissociation of hydrate in sediment
(American Geophysical Union, 2010-03-11)
Gas hydrate formation and dissociation in sediments are accompanied by changes in the bulk volume of the sediment and can lead to changes in sediment properties, loss of integrity for boreholes, and possibly regional ...