Chinese Acad Sci, Inst Geol, Lab Lithosphere Tecton Evolut, Beijing 100029, Peoples R China
; Peking Univ, Inst Heavy Ion Phys, AMS Lab, Beijing 100871, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
Whether the platinum group elements (PGE) can be taken as the indicators of extraterrestrial materials is a very important and interesting scientific problem. It is discussed on the basis of systematic investigation and study of a great amount of related literature. The following conclusions can be obtained: (i) extraterrestrial impact event can cause the PGE anomaly; conversely, the PGE anomaly may not represent the existence of extraterrestrial impact event, because the PGE anomaly can be caused by many terrestrial events (e.g. volcanic activity); ( ii) the PGE anomaly, especially the global PGE anomaly can inspire us to think it from extraterrestrial event, but it may not be as useful as previously thought as unambiguous identifiers of large extraterrestrial impact event in the earth's history.