The thermal regime of a postulated descending lithospheric slab
is calculated. The gravity anomaly associated with such a structure
is large in amplitude and long in wavelengh. Observed free-air
gravity anomalies in the Pacific Northwest do not indicate a gravitational
effect due to a descending slab.
Two hypothetical compensation models...
In order to quantitatively examine the crustal structure of the
Panama Basin without the benefit of local seismic refraction data, the
following assumptions were made: (1) No significant lateral changes
in density take place below a depth of 50 km. (2) The densities of the
crustal layers are those of...
Seismic refraction measurements along two unreversed lines
indicate that the earth's crust is 26 km thick in southeastern Alaska
and 30 km thick along the Inside Passage of British Columbia. The
crust in southeastern Alaska, north of Dixon Entrance, consists of
a layer 9 km thick with a seismic velocity...
The Carnegie Ridge is a linear, aseismic, submarine ridge
lying between the Galapagos Islands and the coast of South America.
A 2300 meter deep saddle near 86°W. longitude divides the ridge into
western and eastern segments. Surface ship, near bottom, and grain
size studies from the saddle have been used...
The concentrations of calcite, opal and quartz have been measured in 113 South Atlantic core tops. The remainder of the total sample has been calculated as clay. A method for the quantitative determination of opal has been developed.
Calcite is the dominant factor in South Atlantic sediments; its pattern can...