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PALEONTOLOGIC EVIDENCE FOR SEDIMENTARY DISPLACEMENT IN NEOGENE FOREARC BASINS OF CENTRAL CHILE

2007; Society for Sedimentary Geology; Volume: 22; Issue: 1 Linguagem: Inglês

10.2110/palo.2005.p05-081r

1938-5323

Kenneth L. Finger, Sven N. Nielsen, Thomas J. DeVries, Alfonso Encinas, Dawn E. Peterson,

Geological formations and processes

Abstract A consensus on the biostratigraphic age and depositional environment of the Navidad, Ranquil, and Lacui formations exposed along the tectonic margin of central Chile has been elusive due to conflicting evidence. This study resolves this dilemma and gains further insight regarding the history of the Chilean coast. Problematic interpretations stem primarily from the remarkable similarity between the molluscan fauna of these units with those well documented for the late Oligocene to early Miocene of Peru. Planktic foraminifers, however, indicate that the Chilean sections accumulated in the late Miocene to early Pliocene interval following a regional hiatus that extends into the Eocene. The prevalence of mixed-depth bathyal assemblages of benthic foraminifers and ostracodes, the majority of which include lower-bathyal (>2000 m) indicators, reveals that downslope displacement was a primary mode of deposition in the basins. Although the molluscan assemblages are dominated by shallow marine taxa, most i...