Puerto Rico: reconnaissance study of the maturation and source rock potential of an oceanic arc involved in a collision

Abstract

Amount and type of organic matter present in Cretaceous and lower Tertiary rocks deposited on Puerto Rico were determined by total organic carbon (TOC) analysis, visual kerogen identification and Rock-Eval pyrolysis. These tests show that the samples commonly contain greater than 1% TOC, and a mixed population of kerogen, with gas-prone kerogen predominating. Based on organic maturity data (vitrinite reflectance, thermal alteration index and Rock-Eval pyrolysis), the maturation history of Puerto Rico is consistent with a two stage thermal model. Before the Oligocene, the island was part of an active magmatic arc. High geothermal gradients and rapid burial left Cretaceous rocks overmature and mature with respect to generated liquid hydrocarbons. After the Eocene, volcanism ceased following collision with the Bahama platform, and lower geothermal gradients combined with slower burial resulted in little maturation. © 1986.