Abstract

A piston core of the oldest sediment yet recovered from the Nazca Plate was retrieved from the outer ridge of the Peru-Chile Trench, below the present calcite compensation level (CCD). The core, PCOD-19, contains assemblages of nanno-fossils of the upper middle Eocene Discoaster saipanensis Subzone, whereas the foraminifera are assigned to earlier zones of the middle Eocene, suggesting reworking. We suggest that these fossils, as well as basalt pebbles in the core, indicate that normal pelagic sedimentation was interrupted and that tectonic events on the sea floor are in part responsible for the disturbances in obducted stratigraphic sequences.

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