Timing and rates of emergence of the Limón and Bocas del Toro basins: Caribbean effects of Cocos Ridge subduction?
Article
Collins, LS, Coates, AG, Jackson, JBC et al. (1995). Timing and rates of emergence of the Limón and Bocas del Toro basins: Caribbean effects of Cocos Ridge subduction?
. 295 263-289. 10.1130/SPE295-p263
Collins, LS, Coates, AG, Jackson, JBC et al. (1995). Timing and rates of emergence of the Limón and Bocas del Toro basins: Caribbean effects of Cocos Ridge subduction?
. 295 263-289. 10.1130/SPE295-p263
Paleobathymetries of consecutively dated stratigraphic sections within the Limón belt, Costa Rica, and Bocas del Toro belt, Panama, are used to calculate rates of emergence for the Caribbean coast of southern Central America over the past 6 m.y. We present estimates of paleoenvironment, paleobathymetry, and rates of emergence for a series of sedimentary units precisely dated as 6.5 to 1.6 Ma. Paleodepths and paleoenvironments are interpreted primarily from preferred habitats of common benthic foraminifera, combined with lithofacies and neotectonics. The Limón and Bocas del Toro belts lie on either side of the northeast-southwest- trending axis of a structural arch that formed from subduction of the Cocos Ridge beneath the Costa Rica-Panama arc complex. Uplift caused by Cocos Ridge subduction began on the southern margin of the arc complex at Burica Peninsula -3.6 Ma, and relatively little uplift occurred after ∼1.6 Ma; net rates of emergence from 3.6 to 1.6 Ma were about 1,000 m/m.y. and near 0 m/m.y. thereafter. Effects of Cocos Ridge subduction were not manifest on the northern margin of the arc complex in the Limón and Bocas del Toro basins until after 1.6 Ma. Although sedimentation patterns and coeval, isobathyal benthic foraminiferal faunas were distinctly different in these basins, indicating at least partial isolation, their histories of uplift are similar. Average emergence rates from ∼6 to 3.5 Ma for the Bocas del Toro basin varied from 24 to 90 m/m.y., which could be accounted for by sea-level fall, and from 3.5 to 1.6 Ma there was no measurable emergence in either basin. However, after 1.6 Ma, rates of emergence were as high as 156 m/m.y. on the Caribbean margin, which we attribute to the penetration of the subducting Cocos Ridge. Thus, uplift of the Caribbean margin in the vicinity of the Cocos Ridge northeast extension began 2 m.y. later and was an order of magnitude slower than uplift of the Pacific margin. Timing for the arrival of the Cocos Ridge at the Caribbean margin is supported by its current subduction rate: If the ridge had traveled northeast from the southern Burica Peninsula at 9 cm/yr, in 2 m.y. it would have crossed 180 km, the approximate distance to the Limón basin.
