Abstract
Detailed fi eld mapping and paleontological dating in the central and southeastern Nicoya Peninsula has revealed Late Cretaceous and Paleogene radiolarian-bearing siliceous mudstones. These rocks belong to two terranes (Matambu and Manzanillo) that are partially contemporaneous with the Nicoya Complex, but are genetically different. While the Nicoya Complex is formed exclusively by intraplate igneous rocks with associated radiolarites, the studied sec- tions include variable amounts of arc-derived volcanic and terrigenous materials. These fore-arc terranes include mafi c to intermediate volcaniclastics and associated pelagic and hemipelagic rocks rich in biogenic silica. Radiolarian preservation in these sediments is often enhanced by the presence of silica-saturated volcanic tuffs and debris. Seven out of 29 samples from different outcrops yielded relatively well-preserved radiolarian faunas. In total, 60 species belonging to 34 genera were present in these faunas, ranging in age from middle Turonian-Santonian to late Thanetian-Ypresian.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call