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Articles 1 - 6 of 6
Full-Text Articles in Entire DC Network
Fire Suppression Impacts On Fuels And Fire Intensity In The Western U.S.: Insights From Archaeological Luminescence Dating In Northern New Mexico, Christopher I. Roos, Tammy M. Rittenour, Thomas W. Swetnam, Rachel A. Loehman, Kacy L. Hollenback, Matthew J. Liebmann, Dana Drake Rosenstein
Fire Suppression Impacts On Fuels And Fire Intensity In The Western U.S.: Insights From Archaeological Luminescence Dating In Northern New Mexico, Christopher I. Roos, Tammy M. Rittenour, Thomas W. Swetnam, Rachel A. Loehman, Kacy L. Hollenback, Matthew J. Liebmann, Dana Drake Rosenstein
Geosciences Faculty Publications
Here, we show that the last century of fire suppression in the western U.S. has resulted in fire intensities that are unique over more than 900 years of record in ponderosa pine forests (Pinus ponderosa). Specifically, we use the heat-sensitive luminescence signal of archaeological ceramics and tree-ring fire histories to show that a recent fire during mild weather conditions was more intense than anything experienced in centuries of frequent wildfires. We support this with a particularly robust set of optically stimulated luminescence measurements on pottery from an archaeological site in northern New Mexico. The heating effects of an October 2012 …
Hematite (U-Th)/He Thermochronometry Detects Asperity Flash Heating During Laboratory Earthquakes, Melissa S. Chapot, Alexis K. Ault, Greg Hirth, Robert G. Mcdermott
Hematite (U-Th)/He Thermochronometry Detects Asperity Flash Heating During Laboratory Earthquakes, Melissa S. Chapot, Alexis K. Ault, Greg Hirth, Robert G. Mcdermott
Geosciences Faculty Publications
Evidence for coseismic temperature rise that induces dynamic weakening is challenging to directly observe and quantify in natural and experimental fault rocks. Hematite (U-Th)/He (hematite He) thermochronometry may serve as a fault-slip thermometer, sensitive to transient high temperatures associated with earthquakes. We test this hypothesis with hematite deformation experiments at seismic slip rates, using a rotary-shear geometry with an annular ring of silicon carbide (SiC) sliding against a specular hematite slab. Hematite is characterized before and after sliding via textural and hematite He analyses to quantify He loss over variable experimental conditions. Experiments yield slip surfaces localized in an ∼5–30-µm-thick …
Crustal Composition And Moho Variations Of The Central And Eastern United States: Improving Resolutionand Geologic Interpretation Of Earthscope Usarray Seismic Images Using Gravity, H. L. Zhang, D. Ravat, Anthony R. Lowry
Crustal Composition And Moho Variations Of The Central And Eastern United States: Improving Resolutionand Geologic Interpretation Of Earthscope Usarray Seismic Images Using Gravity, H. L. Zhang, D. Ravat, Anthony R. Lowry
Geosciences Faculty Publications
EarthScope's USArray Transportable Array has shortcomings for the purpose of interpreting geologic features of wavelengths less than the Transportable Array station spacing, but these can be overcome by using higher spatial resolution gravity data. In this study, we exploit USArray receiver functions to reduce nonuniqueness in the interpretation of gravity anomalies. We model gravity anomalies from previously derived density variations of sedimentary basins, crustal Vp/Vs variation, Moho variation, and upper mantle density variation derived from body wave imaging informed by surface wave tomography to estimate Vp/Vs. Although average densities and density contrasts for …
What Can We Learn From X‐Ray Fluorescence Core Scanning Data? A Paleomonsoon Case Study, Daniel Gebregiorgis, Liviu Giosan, Edmund Hathorne, Pallavi Anand, Katrina Nilsson-Kerr, Anna Plaß, Andreas Lückge, Steven Clemens, Martin Frank
What Can We Learn From X‐Ray Fluorescence Core Scanning Data? A Paleomonsoon Case Study, Daniel Gebregiorgis, Liviu Giosan, Edmund Hathorne, Pallavi Anand, Katrina Nilsson-Kerr, Anna Plaß, Andreas Lückge, Steven Clemens, Martin Frank
Geosciences Faculty Publications
X‐ray fluorescence (XRF) core scanning of marine and lake sediments has been extensively used to study changes in past environmental and climatic processes over a range of timescales. The interpretation of XRF‐derived element ratios in paleoclimatic and paleoceanographic studies primarily considers differences in the relative abundances of particular elements. Here we present new XRF core scanning data from two long sediment cores in the Andaman Sea in the northern Indian Ocean and show that sea level related processes influence terrigenous inputs based proxies such as Ti/Ca, Fe/Ca, and elemental concentrations of the transition metals (e.g., Mn). Zr/Rb ratios are mainly …
Mariana Serpentinite Mud Volcanism Exhumes Subducted Seamount Materials: Implications For The Origin Of Life., Patricia Fryer, C. Geoffrey Wheat, Trevor Williams, Christopher Kelley, Kevin Johnson, Jeffrey Ryan, Walter Kurz, John W. Shervais, Elmar Albers, Barbara Bekins, Baptiste Debret, Jianghong Deng, Yanhui Dong, Philip Eickenbusch, Emanuelle Frery, Yuji Ichiyama, Richard Kevorkian, Et Al.
Mariana Serpentinite Mud Volcanism Exhumes Subducted Seamount Materials: Implications For The Origin Of Life., Patricia Fryer, C. Geoffrey Wheat, Trevor Williams, Christopher Kelley, Kevin Johnson, Jeffrey Ryan, Walter Kurz, John W. Shervais, Elmar Albers, Barbara Bekins, Baptiste Debret, Jianghong Deng, Yanhui Dong, Philip Eickenbusch, Emanuelle Frery, Yuji Ichiyama, Richard Kevorkian, Et Al.
Geosciences Faculty Publications
The subduction of seamounts and ridge features at convergent plate boundaries plays an important role in the deformation of the overriding plate and influences geochemical cycling and associated biological processes. Active serpentinization of forearc mantle and serpentinite mud volcanism on the Mariana forearc (between the trench and active volcanic arc) provides windows on subduction processes. Here, we present (1) the first observation of an extensive exposure of an undeformed Cretaceous seamount currently being subducted at the Mariana Trench inner slope; (2) vertical deformation of the forearc region related to subduction of Pacific Plate seamounts and thickened crust; (3) recovered Ocean …
Oxygen Isotopes In Authigenic Clay Minerals: Toward Building A Reliable Salinity Proxy, Daniel Gebregiorgis, Daniel M. Deocampo, Fred Longstaffe, A. Simpson, Gail M. Ashley, Emily Beverly, Jeremy Delaney, Javier Cuadros
Oxygen Isotopes In Authigenic Clay Minerals: Toward Building A Reliable Salinity Proxy, Daniel Gebregiorgis, Daniel M. Deocampo, Fred Longstaffe, A. Simpson, Gail M. Ashley, Emily Beverly, Jeremy Delaney, Javier Cuadros
Geosciences Faculty Publications
Most clay minerals in sedimentary environments have traditionally been considered to be of detrital origin, but under certain conditions, authigenic clay minerals can form at low temperature through the transformation of precursor clays or as direct precipitates from lake water. Such clay minerals can hold important information about the prevailing climatic conditions during the time of deposition. We present the first quantitative reconstruction of salinity in paleolake Olduvai based on the oxygen‐isotope composition of authigenic clay minerals. We provide a framework illustrating that the isotopic signature of authigenic lacustrine clay minerals is related to the isotopic composition of paleo‐waters, and …