Paleoecology of Oligocene Reef Tract, Southwestern Puerto Rico: ABSTRACT

Abstract

A well-exposed, late Oligocene, barrier-reef sequence, approximately 60 m thick, outcrops for at least 25 km between Guayanilla and Guanica near the southwestern coast of Puerto Rico. A virtually complete range of reef tract environments, from lagoon to deep fore-reef and basin slope, is present. Porites-Caulastrea patch reefs occur in lagoonal miliolid wackestone and packstone, while reef-flat coral shingle is represented by rudaceous grainstones. The reef-crest and reef-front zones are constructed of more than 30 species of hermatypic scleractinian corals. The reef core consists of coral boundstone framework with massive heads in point-to-point contact. The upper fore-reef facies is wackestone with a distinctive assemblage of reef corals, many of which exhibit flattened growth form. Deep fore-reef deposits are packstones of the prolific large foram Lepidocyclina (E.) undosa, while deep-basin facies are composed of pelagic mudstones, clays, and chalks which are interbedded with coral-bearing turbidites. The sequence of reef development displays a classic example of community succession from pioneer through intermediate and climax seral stages, with the coral Porites occupying a dominant to predominant role. End_of_Article - Last_Page 976------------