Publication

More than three decades have passed since the discovery of anomalies in the abundance of platinum group elements (PGEs) across sections of Cretaceous/Paleogene (K/Pg) strata from Gubbio (Italy) and Caravaca (Spain), which have been attributed to a bolide impact. This remains one of the most significant findings in the field of Earth science. After the discovery, the PGE anomaly at the K/Pg boundary has been confirmed from more than 120 sites. Bolide impacts are not limited to the K/Pg boundary, but occurred throughout Earth’s history. Pelagic deep-sea sediments, such as bedded chert, are repositories of information regarding impact events over geologic time, because they preserve long-duration continuous records with low sedimentation rates. This paper reviews geochemical studies reporting evidence for a large impact event in the Triassic bedded chert sequences from a Jurassic accretionary complex in Japan. Geochemical data on PGEs and radiogenic osmium (Os) isotope ratios (187Os/188Os) in the bedded chert provide information regarding the type and size of impactor.