ABSTRACT
A geophysical and geological survey conducted over the landward slope of the Middle America Trench offshore Guatemala has revealed lanward - dipping reflectors which are associated with high compressional wave velocities, large magnetic anomalies, and basic/ultrabasic rock. Multifold seismic reflection data reveal that the edge of the continental shelf is a structural high on which Cretaceous and younger sediments of the shelf basin onlap and pinch out. The upper part of the continental slope is covered in most places by a 0.5 to 1.0 km thick sediment apron with seismic velocities of 1.8 to 2.6 km/sec. Immediately beneath the sediment apron an irregular surface is the top of an interval with velocities of 4.3 to 4.7 km/sec. Within this interval landward - dipping reflections are traced to about 6 km below sea level. Above this zone of dipping reflectors two positive magnetic anomalies are observed as well as a positive gree - air gravity anomaly reported by other workers (AU)
Subject(s)
Geology , Earthquakes , Central AmericaABSTRACT
Deep sounding seismic reflection data show undeformed reflectors at depths down to 11 kilometers beneath the continental rise and abyssal plain and 7 kilometers in basins of the lower slope. Weak reflectors are visible beneath the salt of the Sigsbee Scarp and within salt ridges separating the lower slope basins.
ABSTRACT
Horizon beta is a subbottom reflector in the North Atlantic deep ocean sediments that extends over a large portion of the North America basin. Cores from an outcrop of beta contained shallow-water Aptian-Albian sediments and deep-water Cenomanian sediments. A core near an outcrop of a deeper horizon, horizon B, contained shallow-water Lower Cretaceous (Barremian-Hauterivian) sediments. These cores can be interpreted to support extensive subsidence of the eastern portion of the basin in early Cretaceous time. It is equally likely that the shallow-water deposits are a result of sediments slumping into an already deep basin. A reconciliation of these interpretations depends upon the JOIDES project.
ABSTRACT
A method is proposed whereby potable water may be obtained by condensing moisture from the atmosphere in suitable seashore or island areas. Deep, cold, offshore seawater is used as a source of cold and is pumped to condensers set up on shore to intercept the flow of highly humid, tropical, maritime air masses. This air, when cooled, condenses moisture, which is conducted away and stored for use as a water supply. Windmill-driven generators would supply low-cost power for the operation. Side benefits are derived by using the nutritious deep water to support aquiculture in nearby lagoons or to enhance the productivity of the outfall area. Additional benefits are derived from the condenser as an air-conditioning device for nearby residents. The islands of the Caribbean are used as an example of a location in the trade-winds belt where nearly optimum conditions for the operation of this system can be found.
