Heavy minerals can contain potentially economic amounts of
metals as both matrix and trace constituents. Such minerals appear
as unconsolidated black sands on the continental shelf off southwest
Oregon and along the Oregon coast. Two diverse energies are considered in this investigation. Environmental energy of the depositional
regimen, Part I;...
A total of 57 core top samples from the Panama Basin were
used in a quantitative study of complete radiolarian thanatocoenoses
to determine whether surface oceanographic conditions are reflected
in the microplankton faunas deposited onto and buried in the sea floor.
Information obtained from this study was used to resolve...
A new technique for determining the amount of opal in deep-sea
sediments of any age is described. Using a normative calculation, a
portion of the analytical silica concentration of sediments is subtracted
as non-biogenic in proportion to the concentration of aluminum in the
sample. The ratio of SiO₂:Al₂O₃ used to...
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...
Many sediments, including the fine-grained pelagic deposits,
possess polymodal grain size distributions. Resolution of individual
modes show them to be related either to compositional fractions or to
depositional processes or both, and sometimes permits the tracing
of dispersal patterns. The Cahn sedimentation balance provides a
means of obtaining continuous cumulative...
The Cocos Gap is a deeper portion, or saddle, of the Cocos
Ridge and forms part of the western boundary of the Panama Basing
It is probably typical of saddles within most submarine ridges, In
order to determine the mechanisms controlling sediment dispersal,
the nature and sources of the sediments...
The opening of the South Atlantic between 140 and 90 m. y. B. P.
occurred about two poles of rotation. The initial pole of rotation was
maintained until Africa and South America were completely separated.
The subsequent removal of restraints imposed by the pre-existing
structure of Africa and South America...
The Antarctic Ocean during the Cenozoic experienced four periods of increased surface productivity: the Middle Eocene; the beginning of the Miocene; the Middle Miocene; and near the Miocene-Pliocene boundary. The fourth increase in productivity began five
million years ago and has since progressively increased to the present level of intense...
The portion of the East Pacific Rise (EPR) between 5° and 12°S
can be subdivided into three areas by fracture zones that offset the
rise axis at about 6.5°S and 9°S. In all three regions, the spreading
axis of the EPR is defined by a topographic block 300 to 350...
