STROMATOLITIC IRON-OXIDES - EVIDENCE THAT SEA-LEVEL CHANGES CAN CAUSE SEDIMENTARY IRIDIUM ANOMALIES

Abstract

Considers the origin of an Ir-rich unit near the Late Devonian Frasnian-Famennian (F/F) boundary in the Canning basin of Western Australia. Examines two lithologically similar Early Cambrian and late Oligocene age horizons from southeastern Australia. Suggests that all of these Ir-rich stromatolitic beds developed in response to relative sea-level change and represent periods of condensed marine sedimentation. It is probable that condensation was produced by rapid drowning following subaerial exposure. -Authors