Publications
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Surficial deposits at Gusev crater along Spirit Rover traverses
The Mars Exploration Rover Spirit has traversed a fairly flat, rock-strewn terrain whose surface is shaped primarily by impact events, although some of the landscape has been altered by eolian processes. Impacts ejected basaltic rocks that probably were part of locally formed lava flows from at least 10 meters depth. Some rocks have been textured and/or partially buried by windblown sediments less
Authors
J. A. Grant, R. Arvidson, J.F. Bell, N.A. Cabrol, M. H. Carr, P. Christensen, L. Crumpler, D.J. Des Marais, B.L. Ehlmann, J. Farmer, M. Golombek, F.D. Grant, R. Greeley, Kenneth E. Herkenhoff, R. Li, H.Y. McSween, D. W. Ming, J. Moersch, J. W. Rice, S. Ruff, L. Richter, S. Squyres, R. Sullivan, C. Weitz
The Spirit Rover's Athena science investigation at Gusev crater, Mars
The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former take, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coati
Authors
S. W. Squyres, R. E. Arvidson, J.F. Bell, J. Brückner, N.A. Cabrol, W. Calvin, M. H. Carr, P. R. Christensen, B. C. Clark, L. Crumpler, D.J. Des Marais, C. D'Uston, T. Economou, J. Farmer, W. Farrand, W. Folkner, M. Golombek, S. Gorevan, J. A. Grant, R. Greeley, J. Grotzinger, L. Haskin, Kenneth E. Herkenhoff, S. Hviid, J. Johnson, G. Klingelhofer, A. Knoll, G. Landis, M. Lemmon, R. Li, M.B. Madsen, M. C. Malin, S. M. McLennan, H.Y. McSween, D. W. Ming, J. Moersch, R.V. Morris, T. Parker, J. W. Rice, L. Richter, R. Rieder, M. Sims, M. Smith, P. Smith, Laurence A. Soderblom, R. Sullivan, H. Wanke, T. Wdowiak, M. Wolff, A. Yen
Oxidized sulfur-rich mafic magma at Mount Pinatubo, Philippines
Basaltic fragments enclosed in andesitic dome lavas and pyroclastic flows erupted during the early stages of the 1991 eruption of Mount Pinatubo, Philippines, contain amphiboles that crystallized during the injection of mafic magma into a dacitic magma body. The amphiboles contain abundant melt inclusions, which recorded the mixing of andesitic melt in the mafic magma and rhyolitic melt in the dac
Authors
J.C.M. de Hoog, K.H. Hattori, R. P. Hoblitt
Chemical versus temporal controls on the evolution of tholeiitic and calc-alkaline magmas at two volcanoes in the Alaska-Aleutian arc
The Alaska-Aleutian island arc is well known for erupting both tholeiitic and calc-alkaline magmas. To investigate the relative roles of chemical and temporal controls in generating these contrasting liquid lines of descent we have undertaken a detailed study of tholeiitic lavas from Akutan volcano in the oceanic A1eutian arc and calc-alkaline products from Aniakchak volcano on the continental A1a
Authors
R. George, S. Turner, C. Hawkesworth, C. R. Bacon, C. Nye, P. Stelling, S. Dreher
Short-wavelength infrared (1.3-2.6 μm) observations of the nucleus of Comet 19P/Borrelly
During the last two minutes before closest approach of Deep Space 1 to Comet 19P/Borrelly, a long exposure was made with the short-wavelength infrared (SWIR) imaging spectrometer. The observation yielded 46 spectra covering 1.3–2.6 μm; the footprint of each spectrum was ∼160 m × width of the nucleus. Borrelly's highly variegated and extremely dark 8-km-long nucleus exhibits a strong red slope in i
Authors
Laurence A. Soderblom, D.T. Britt, R. H. Brown, B. J. Buratti, Randolph L. Kirk, T.C. Owen, R.V. Yelle
Stress field variations in the Swiss Alps and the northern Alpine foreland derived from inversion of fault plane solutions
This study is devoted to a systematic analysis of the state of stress of the central European Alps and northern Alpine foreland in Switzerland based on focal mechanisms of 138 earthquakes with magnitudes between 1 and 5. The most robust feature of the results is that the azimuth of the minimum compressive stress, S3, is generally well constrained for all data subsets and always lies in the NE quad
Authors
U. Kastrup, M.L. Zoback, N. Deichmann, Kenneth F. Evans, D. Giardini, A.J. Michael
Effects of fault dip and slip rake angles on near-source ground motions: Why rupture directivity was minimal in the 1999 Chi-Chi, Taiwan, earthquake
We study how the fault dip and slip rake angles affect near-source ground velocities and displacements as faulting transitions from strike-slip motion on a vertical fault to thrust motion on a shallow-dipping fault. Ground motions are computed for five fault geometries with different combinations of fault dip and rake angles and common values for the fault area and the average slip. The nature of
Authors
Brad T. Aagaard, J. F. Hall, T. H. Heaton
Ultra-high chlorine in submarine Kı̄lauea glasses: Evidence for direct assimilation of brine by magma
Basaltic glass grains from the submarine south flank of Kı̄lauea, Hawai′i, have Cl concentrations of 0.01–1.68 wt%, the latter being the highest Cl content yet recorded for a Hawaiian glass. The high-Cl glass grains are products of brine assimilation by tholeiite magma. The glasses are grains in a sandstone clast from bedded breccias draping the southwestern margin of Kı̄lauea’s submarine midslope
Authors
Michelle L. Coombs, Thomas W. Sisson, Jun-Ichi Kimura
Gas evolution in eruptive conduits: Combining insights from high temperature and pressure decompression experiments with steady-state flow modeling
In this paper we examine the consequences of bubble nucleation mechanism on eruptive degassing of rhyolite magma. We use the results of published high temperature and pressure decompression experiments as input to a modified version of CONFLOW, the numerical model of Mastin and Ghiorso [(2000) U.S.G.S. Open-File Rep. 00-209, 53 pp.] and Mastin [(2002) Geochem. Geophys. Geosyst. 3, 10.1029/2001GC00
Authors
M. Mangan, L. Mastin, T. Sisson
Mapping recent lava flows at Westdahl Volcano, Alaska, using radar and optical satellite imagery
Field mapping of young lava flows at Aleutian volcanoes is logistically difficult, and the utility of optical images from aircraft or satellites for this purpose is greatly reduced by persistent cloud cover. These factors have hampered earlier estimates of the areas and volumes of three young lava flows at Westdahl Volcano, including its most recent (1991–1992) flow. We combined information from s
Authors
Z. Lu, Russ Rykhus, Timothy Masterlark, K.G. Dean
Pedogenic silica accumulation in chronosequence soils, southern California
Chronosequential analysis of soil properties has proven to be a valuable approach for estimating ages of geomorphic surfaces where no independent age control exists. In this study we examined pedogenic silica as an indicator of relative ages of soils and geomorphic surfaces, and assessed potential sources of the silica. Pedogenic opaline silica was quantified by tiron (4,5-dihydroxy-1,3-benzene-di
Authors
K.J. Kendrick, R.C. Graham
Landslides triggered by the 2002 Denali fault, Alaska, earthquake and the inferred nature of the strong shaking
The 2002 M7.9 Denali fault, Alaska, earthquake triggered thousands of landslides, primarily rock falls and rock slides, that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 15 ?? 106 m3. The pattern of landsliding was unusual; the number of slides was less than expected for an earthquake of this magnitude, and the landslides were concentrated in
Authors
R. W. Jibson, E. L. Harp, W. Schulz, D. K. Keefer