info:eu-repo/semantics/article
Type, distribution, and origin of sediments of the Gandoca-Manzanillo National Wildlife Refuge, Limón, Costa Rica
Type, distribution, and origin of sediments of the Gandoca-Manzanillo National Wildlife Refuge, Limón, Costa Rica
Autor
Cortés, Jorge
Barrantes, Manuel
Denyer, Percy
Institución
Resumen
Sediments and the marine current system at the Gandoca-Manzanilio National Wildlife Refuge. Caribbean coast of Costa Rica, define two sedimentary environments. One between Punta Uva and Manzanillo. where sediments were derived from the coral reefs and local geological fonnations. The Other lies between Punta Mona and Rio Sixaola. where sediments arrive primarily from outside tile an:a. fine-grained sediments were collected off rivers and creeks mouths. and adjacent beaches. The highest percentage of carbonates (60 to 80 %) was found off Punta Uva, and consisted mainly of mollusk, algal and coral fragments, and Foraminifera. Magnetite found in large quantities off Manzanillo, and also observed on the beach. was derived locally from the Rio Banano Formation. Clay and silt were found in high concentrations from Punta Mona to Rio Sixaola. Other minerals. pyroxene and hyrobiotile, probably originated from the erosion of intrusive rock s cropping out in the central section of the Talamanea Range. The sediment plume of Rio Sixaola extends several kilometers off shore, flowing northwest and affecting coral reefs off Punta Mona. Other an:as of the Refuge an: not exposed to high concentrations of terrigenous sediments. However, as a result of deforestation, new constructions and removal of riparian and coastal forests, more coral reefs of the Refuge will be affected by sediments. El origen de los sedimentos y el sistema de corrientes en el Refugio Nacional de Vida Silvestre Gandoca-Manzanillo definen dos ambientes sedimentarios. El primero, entre Punta Uva y Manzanillo, donde los sedimen Punta Uva y Manzanillo, donde los sedimen Punta Mona y el Rio Sixaola, donde los sedimentos se originan principalmente fuera del área. Se recolectaron sedimentos finos en la boca de los ríos y quebradas, y en las playas adjacentes. El porcentaje más alto de carbonatos (60 a 80%) se encontró en Punta Uva, y consiste principalmeme de fragmentos de moluscos, algas y corales, y foraminiferos. Se encontró magnetita en grandes cantidades frente a Manzanillo, y en la playa; derivada localmente de la Fondación Río Banana. Arcillas y limos son abundantes desde Punta Mona hasta el Río Sixaola. Otros minerales, piroxena e hydrobiotita, probablemente son producto de la erosión de las rocas intrusivas que afloran en la sección central de la Cordillera de Talamanca. La pluma de sedimentos del Río Sixaola se extiende varies kilómetros mar afuera, fluyendo hacia el noroeste y afectando los arrecifes coralinos de Punta Mona. Otras áreas del Refugio no están expuestas a tantos sedimentos terrígenos, pero, conforme se altera la región, por deforestación, construcciones, y remoción del bosque riberino y costero, más arrecifes coralinos del Refugio van a ser afectados por sedimentos.