EVIDENCE FOR THE LATE PROTEROZOIC CATASTROPHIC EVENTS IN XINGSHAN COUNTY:MICROSPHERULES AND NEGATIVE ANOMALIES OF CARBON ISOTOPES

K-feldspar microspherules and negative anomaly of carbon isotopes are found in silvervanadium ore beds in the Baiguoyuan ore district, Xingshan County, Hubei Province, whichare evidence of Late Proterozoic catastrophic events on the Yangtze platform. At the bottomof the Ag-V ore beds,there is a boulder clay layer marking the beginning of the events. ManyK-bearing microspherults are found within the layer as well in black shales above it,whosechemical composition is comparative to that of tektite of impact origin. The thin carbonatebeds （mainly dolomite） intercalated in the black shales show the tendency of δ18O and δ13Ctowards the largest negative values （δ13C=-8. 62‰, PDB and δ18O=-6. 08‰ PDB）. Thereare anomalies of trace elements and REE in the black shales too. The cause of the catastrophic events might be due to extraterrestrial impact or volcanic eruption.