Publications
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Pre-eruption recharge of the Bishop magma system Pre-eruption recharge of the Bishop magma system
The 650 km3 rhyolitic Bishop Tuff (eastern California, USA), which is stratigraphically zoned with respect to temperatures of mineral equilibration, reflects a corresponding thermal gradient in the source magma chamber. Consistent with previous work, application of the new TitaniQ (Ti-in-quartz) thermometer to quartz phenocryst rims documents an ∼100 °C temperature increase with chamber...
Authors
D.A. Wark, W. Hildreth, F.S. Spear, D.J. Cherniak, E.B. Watson
A closer look at water-related geologic activity on Mars A closer look at water-related geologic activity on Mars
Water has supposedly marked the surface of Mars and produced characteristic landforms. To understand the history of water on Mars, we take a close look at key locations with the High-Resolution Imaging Science Experiment on board the Mars Reconnaissance Orbiter, reaching fine spatial scales of 25 to 32 centimeters per pixel. Boulders ranging up to ∼2 meters in diameter are ubiquitous in...
Authors
Alfred S. McEwen, C.J. Hansen, W.A. Delamere, E. M. Eliason, Kenneth E. Herkenhoff, Laszlo P. Keszthelyi, V. C. Gulick, Randolph L. Kirk, M. T. Mellon, J. A. Grant, N. Thomas, C.M. Weitz, S. W. Squyres, N.T. Bridges, S.L. Murchie, F. Seelos, K. Seelos, C.H. Okubo, M.P. Milazzo, L.L. Tornabene, W.L. Jaeger, S. Byrne, P.S. Russell, J.L. Griffes, S. Martinez-Alonso, A. Davatzes, F. C. Chuang, B.J. Thomson, K.E. Fishbaugh, C. M. Dundas, K.J. Kolb, M. E. Banks, J.J. Wray
Ensuring confidence in radionuclide-based sediment chronologies and bioturbation rates Ensuring confidence in radionuclide-based sediment chronologies and bioturbation rates
Sedimentary records of naturally occurring and fallout-derived radionuclides are widely used as tools for estimating both the ages of recent sediments and rates of sedimentation and bioturbation. Developing these records to the point of data interpretation requires careful sample collection, processing, analysis and data modeling. In this work, we document a number of potential pitfalls...
Authors
John Crusius, Timothy C. Kenna
Probabilistic volcanic hazard and risk assessment Probabilistic volcanic hazard and risk assessment
[No abstract available]
Authors
W. Marzocchi, A. Neri, C. G. Newhall, P. Papale
Deglacial climate variability in central Florida, USA Deglacial climate variability in central Florida, USA
Pollen and ostracode evidence from lacustrine sediments underlying modern Tampa Bay, Florida, document frequent and abrupt climatic and hydrological events superimposed on deglacial warming in the subtropics. Radiocarbon chronology on well-preserved mollusk shells and pollen residue from core MD02-2579 documents continuous sedimentation in a variety of non-marine habitats in a karst...
Authors
Debra A. Willard, C.E. Bernhardt, G. R. Brooks, T. M. Cronin, T. Edgar, R. Larson
Emplacement of a silicic lava dome through a crater glacier: Mount St Helens, 2004-06 Emplacement of a silicic lava dome through a crater glacier: Mount St Helens, 2004-06
The process of lava-dome emplacement through a glacier was observed for the first time after Mount St Helens reawakened in September 2004. The glacier that had grown in the crater since the cataclysmic 1980 eruption was split in two by the new lava dome. The two parts of the glacier were successively squeezed against the crater wall. Photography, photogrammetry and geodetic measurements...
Authors
Joseph S. Walder, Richard G. Lahusen, James W. Vallance, Steve P. Schilling
Thirty-one years of debris-flow observation and monitoring near La Honda, California, USA Thirty-one years of debris-flow observation and monitoring near La Honda, California, USA
From 1975 until 2006,18 intense storms triggered at least 248 debris flows within 10 km2 northwest of the town of La Honda within the Santa Cruz Mountains, California. In addition to mapping debris flows and other types of landslides, studies included soil sampling and geologic mapping, piezometric and tensiometer monitoring, and rainfall measurement and recording. From 1985 until 1995...
Authors
G. F. Wieczorek, R. C. Wilson, S. D. Ellen, M.E. Reid, A. S. Jayko
Integrated geologic and geophysical studies of North American continental intraplate seismicity Integrated geologic and geophysical studies of North American continental intraplate seismicity
The origin of earthquakes within stable continental regions has been the subject of debate over the past thirty years. Here, we examine the correlation of North American stable continental region earthquakes using five geologic and geophysical data sets: (1) a newly compiled age-province map; (2) Bouguer gravity data; (3) aeromagnetic anomalies; (4) the tectonic stress field; and (5)...
Authors
X. Van Lanen, Walter D. Mooney
Survey of TES high albedo events in Mars' northern polar craters Survey of TES high albedo events in Mars' northern polar craters
Following the work exploring Korolev Crater (Armstrong et al., 2005) for evidence of crater interior ice deposits, we have conducted a survey of Thermal Emission Spectroscopy (TES) temperature and albedo measurements for Mars' northern polar craters larger than 10 km. Specifically, we identify a class of craters that exhibits brightening in their interiors during a solar longitude, Ls...
Authors
J.C. Armstrong, S.K. Nielson, Timothy N. Titus
Restoring coastal wetlands that were ditched for mosquito control: a preliminary assessment of hydro-leveling as a restoration technique Restoring coastal wetlands that were ditched for mosquito control: a preliminary assessment of hydro-leveling as a restoration technique
The wetlands surrounding Tampa Bay, Florida were extensively ditched for mosquito control in the 1950s. Spoil from ditch construction was placed adjacent to the wetlands ditches creating mound-like features (spoil-mounds). These mounds represent a loss of 14% of the wetland area in Tampa Bay. Spoil mounds interfere with tidal flow and are locations for non-native plants to colonize (e.g...
Authors
Thomas J. Smith, Ginger Tiling, Pamela S. Leasure
Altered mangrove wetlands as habitat for estuarine nekton: are dredged channels and tidal creeks equivalent? Altered mangrove wetlands as habitat for estuarine nekton: are dredged channels and tidal creeks equivalent?
Hasty decisions are often made regarding the restoration of "altered" habitats, when in fact the ecological value of these habitats may be comparable to natural ones. To assess the "value" of altered mangrove-lined habitats for nekton, we sampled for 1 yr within three Tampa Bay wetlands. Species composition, abundance, and spatial distribution of nekton assemblages in permanent subtidal...
Authors
Justin M. Krebs, Adam B. Brame, Carole C. McIvor
Submarine groundwater discharge to Tampa Bay: Nutrient fluxes and biogeochemistry of the coastal aquifer Submarine groundwater discharge to Tampa Bay: Nutrient fluxes and biogeochemistry of the coastal aquifer
To separately quantify the roles of fresh and saline submarine groundwater discharge (SGD), relative to that of rivers, in transporting nutrients to Tampa Bay, Florida, we used three approaches (Darcy's Law calculations, a watershed water budget, and a 222Rn mass-balance) to estimate rate of SGD from the Pinellas peninsula. Groundwater samples were collected in 69 locations in the...
Authors
Kevin D. Kroeger, Peter W. Swarzenski, Jason Greenwood, Christopher Reich