Publications

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 increasing time

The aim of our research programme is to explore the rheological behavior of H2O ices under conditions appropriate to the interiors of the icy satellites of the outer planets in order to give insight into their deformation. To this end, we have performed over 100 constant-strain-rate compression tests at pressures to 500 MPa and temperatures as low as 77 K. At P > 30 MPa, ice Ih fails by a shear in

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 times must

No abstract available. 

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 ice layers

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 and snow tha

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 other below

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 which λ v

No abstract available.

No abstract available.

Georges Bank is a shallow part of the Atlantic continental shelf southeast of New England (Emery and Uchupi, 1972, 1984). This bank, however, is merely the upper surface of several sedimentary basins overlying a block-faulted basement of igneous and metamorphic crystalline rock. Sedimentary rock forms a seaward-thickening cover that has accumulated in one main depocenter and several ancillary depr

No abstract available.