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Crustal structure beneath exposed accreted terranes of Southern Alaska Crustal structure beneath exposed accreted terranes of Southern Alaska

The crustal structure beneath the exposed terranes of southern Alaska has been explored using coincident seismic refraction and reflection profiling. A wide-angle reflector at 8-9 km depth, at the base of an inferred low-velocity zone, underlies the Peninsular and Chugach terranes, appears to truncate their boundary, and may represent a horizontal decollement beneath the terranes. The...
Authors
Gary S. Fuis, E. L. Ambos, Walter D. Mooney, R.A. Page, Michael A. Fisher, Thomas M. Brocher, J.J. Taber

Recording and processing procedures for multi-channel seismic-reflection data collected in the western Ross Sea, Antarctica Recording and processing procedures for multi-channel seismic-reflection data collected in the western Ross Sea, Antarctica

During 1984, over 2300 km of multichannel seismic-reflection data were recorded by the U.S. Geological Survey in the western Ross Sea and Iselin Bank regions. A temporary loss and sinking of the streamer led to increasing the streamer tow depth to 20 m, which resulted in some attenuation of frequencies in the 30-50 Hz range but no significant difference in resolution of the stacked data...
Authors
Shawn V. Dadisman, Holly F. Ryan, Dennis M. Mann

Ionic conductivity of quartz: DC time dependence and transition in charge carriers Ionic conductivity of quartz: DC time dependence and transition in charge carriers

The time dependence of DC electrical conductivity in the c-axis direction of quartz can be accounted for by a transition in charge carriers from interstitial alkali impurities to interstitial H. The diffusive transport rates of Li, Na, and K are rapid parallel to c and have been shown to be responsible for the highly anisotropic electrical conductivity measured at short times. With...
Authors
A. K. Kronenberg, Stephen H. Kirby

Inelastic properties of several high pressure crystalline phases of H2O: Ices II, III, and V Inelastic properties of several high pressure crystalline phases of H2O: Ices II, III, and V

We have performed deformation experiments on cylinders of polycrystalline H2O at temperatures from 178 to 257 K at pressures to 500 MPa in the stability fields of ices II, III, and V. Ice II is the strongest of the phases, having a strength under laboratory conditions roughly comparable to that of ice Ih. Ice V is somewhat weaker than ice II. Ice III is extremely weak and over geologic...
Authors
William B. Durham, Stephen H. Kirby, H. C. Heard, Laura A. Stern

I. Thermal evolution of Ganymede and implications for surface features. II. Magnetohydrodynamic constraints on deep zonal flow in the giant planets. III. A fast finite-element algorithm for two-dimensional photoclinometry I. Thermal evolution of Ganymede and implications for surface features. II. Magnetohydrodynamic constraints on deep zonal flow in the giant planets. III. A fast finite-element algorithm for two-dimensional photoclinometry

The work is divided into three independent papers: PAPER I: Thermal evolution models are presented for Ganymede, assuming a mostly differentiated initial state of a water ocean overlying a rock layer. The only heat sources are assumed to be primordial heat (provided by accretion) and the long-lived radiogenic heat sources in the rock component. As Ganymede cools, the ocean thins, and two...
Authors
Randolph L. Kirk

Snow and ice studies by thematic mapper and multispectral scanner Landsat images Snow and ice studies by thematic mapper and multispectral scanner Landsat images

Digitally enhanced Landsat Thematic Mapper (TM) images of Antarctica reveal snow and ice features to a detail never seen before in satellite images. The six TM reflective spectral bands have a nominal spatial resolution of 30 m, compared to 80 m for the Multispectral Scanner (MSS). TM bands 2–4 are similar to the MSS bands. TM infra-red bands 5 and 7 discriminate better between clouds...
Authors
Olav Orheim, Baerbel K. Lucchitta

Thermal evolution of a differentiated Ganymede and implications for surface features Thermal evolution of a differentiated Ganymede and implications for surface features

Thermal evolution models are presented for Ganymede, assuming a mostly differentiated initial state of a water ocean overlying a rock layer. The only heat sources are assumed to be primordial heat (provided by accretion) and the long-lived radiogenic heat sources in the rock component. As Ganymede cools, the ocean thins, and two ice layers develop, one above composed of ice I, and the...
Authors
Randolph L. Kirk, David J. Stevenson

Hydromagnetic constraints on deep zonal flows in the giant planets Hydromagnetic constraints on deep zonal flows in the giant planets

The observed zonal flows of the giant planets will, if they penetrate below the visible atmosphere, interact significantly with the planetary magnetic field outside the metallized core. The appropriate measure of this interaction is the Chandrasekhar number Q = H^2 /4πρνα^2 λ (H = radial component of the magnetic field, ν = eddy viscosity, λ = magnetic diffusivity, α^-1 = length scale on...
Authors
Randolph L. Kirk, David J. Stevenson
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