Geophysical reconnaissance of the Western Cayman Ridge

Abstract

Magnetic, gravity, and seismic reflection profiles indicate that the western Cayman ridge is composed of sedimentary rocks overlying a magnetic basement. Presumably, the ridge is a piece of continental material rifted northward from the Nicaraguan rise. The ridge changes trend from approximately E-W to NE-SW near its western end and seems to extend into the highly fractured belt between the Polochic and Motagua fault zones of eastern Guatemala. As the ridge probably forms the mutual boundary of the North American and Caribbean lithospheric plates, the change in trend combined with the left lateral plate motion may account for the extensional pattern in northeastern Central America.

Late Cretaceous‐Recent Tectonostratigraphic Evolution of the Yucatan Back‐Arc Basin, Northern Caribbean Sea

“…Although no scientific or exploratory wells have been drilled in the basin, seismic reflection data were used to infer the marine sedimentary facies (Dillon & Vedder, 1973; Dillon et al., 1972; Malin & Dillon, 1973; Vedder et al., 1973). A sequence of weak reflectors was observed to be overlain by an upper sequence of strongly interbedded and continuous reflectors.…”

“…Three profiles are used to show the seismic reflection character and crustal thickness of the main crustal domains and their fault boundaries. Because there are no wells to study the rock properties of the sediments and basement in the Yucatan Basin, we used densities from previous gravity studies in our gravity modeling (Bowin, 1968; Case, 1975; Dillon & Vedder, 1973; Dillon et al., 1972; Erickson et al., 1972; Lin et al., 2019; Malin & Dillon, 1973).…”

“…This gravity high covers an area of approximately 68,000 km 2 that is visible from both gravity data sets and is delimited to the west by the linear Marginal Fault Zone and by the extension of the La Trocha Fault to the southeast that extends as far east as the thrust belt of central Cuba (Rosencrantz, 1990). Previous studies used refraction and gravity modeling for the Yucatan Basin to determine that the area of oceanic crust in the western Yucatan Basin thickens southward to more than 18 km island arc crust beneath the Cayman Ridge (Bowin, 1968; Dillon & Vedder, 1973; Ewing et al., 1960; Malin & Dillon, 1973).…”