AbstractsEarth & Environmental Science

The provenance of middle to late Miocene clastic sediments of Cibao basin in northern Hispaniola has been assessed via integrated methods including detrital framework modes, clay mineral assemblages and ratios, the composition of individual feldspar grains, and the distribution and abundance of trace elements and rare earth elements (REE). Framework modes of middle to late Miocene clastic samples suggest a source mainly from recycled orogen provenance. Individual feldspar compositions determined by electron microprobe analysis indicate derivation from plutonic, metamorphic, and possibly volcanic sources. Trace elements and REE data demonstrate that the middle and late Miocene sediments in the central to eastern Cibao basin display two geochemically distinctive type features. Type 1 sediments, with relatively lower total REE, Th, Sc and Cr+Ni values, correspond to relatively higher chlorite/illite ratio and varied feldspar abundance. Type 2 sediments, with relatively higher total REE, Th, Sc and Cr+Ni values, are consistent with lower chlorite/illite ratio and lower percentage of feldspar. These geochemical characteristics suggest that middle to late Miocene clastic sediments in Cibao basin are related to an active continental margins setting. Multiple sources are suggested by this study. A northern source is the Cordillera Septentrional, and a southern source is the Cordillera Central.