LAUSR

Abstract U–Pb geochronology on detrital zircons from the Neogene sediments of San Carlos Basin in Costa Rica, yielded a wide range of ages, from Paleoproterozoic to Cenozoic. The most representative is the Miocene population, constrained to a maximum depositional age of 6.9 ± 0.2 Ma. It reflects the local volcanic activity of the evolving island arc and late Miocene to Pliocene basin sedimentation. Cenozoic ages vary from ca. 5.8–56.1 Ma and Mesozoic ages from ca. 68.9–243 Ma. Other zircon populations yielded a variety of older ages: Paleozoic (ca. 264.9–536.5 Ma) and Proterozoic (ca. 552–1910 Ma). Such ages previously undiscovered in Costa Rica bring new insights on provenance and indicate multistage zircon recycling from a variety of sources. The presence of pre-Mesozoic detrital zircons indicates the influx of recycled sediments from older units, possibly from exhumed Precambrian and Paleozoic continental terranes or blocks from the north of Central America (Chortis and Patuca) in Guatemala, Honduras, north of Nicaragua, and probably from southern Mexico.