RECENT PROGRESS OF THE STUDY ON NEOGENE-QUATERNARY BOUNDARY IMPACT EVENT

Up to now, five kinds of micrograins, including cosmic dust, microtektites, volcanic spherules, impact volcanic ash and organic spherules, especially the iridium anomalies in bulk rock and micrograins have been discovered in the strata around the Gauss/Matuyama bound-ary in Duanjiapo loess/red clay section located at the south margin of the North China Loess Plateau.From these records, tow impact events with a time interval of ca.0.1Ma have been determined, having an age of 2.53-2.48MaBP and 2.43-2.42MaBP respectively.The early one, as can be correlated not only to the climate stratigraphic red clay/loess transition, but al-so to the magnetostratigraphic Gauss/Matuyama transition, is undoubtedly the Neogene/Quaternary boundary impact event.It is also shown in this paper that a comprehensive mode of origin can be used for explanation of the coexistence of impact records with different prop-erties.