Chronology and geochemistry of the Caribbean Large Igneous Province in Jamaica

Abstract

Jamaica has a complex geological history with rocks belonging to the Cretaceous Caribbean Large Igneous Province (CLIP) in the east and Cretaceous oceanic island arc rocks in the centre and west. We present a new geochemical dataset for the CLIP and correlate this dataset and previous datasets using radiolarians and planktic foraminifers to the geological timescale. The palaeontological dating indicates that two phases of plateau activity – ‘main’ phase in the late Turonian-mid Coniacian (c. 92-87 Ma) and an ‘extended’ phase in the Coniacian to mid Campanian (c. 88-75 Ma). These phases are also seen in the Beata Ridge and on the Lower Nicaragua Rise. The geochemistry indicates that both phases are typical large igneous province plateau basalts. The ‘main’ phase has slightly more depleted light rare earth elements than the extended phase, indicating mantle source heterogeneity, and a (Sm/Yb)n >1 indicates a deeper average depth of melting for the ‘main’ phase. The association of the basalts with sediments containing specific microfossil assemblages clearly demonstrates the existence of these two magmatic phases in Jamaica.