UPPER ORDOVICIAN (KATIAN) δ13C CHEMOSTRATIGRAPHY:A TRANS-ATLANTIC COMPARISON

摘要

Extensive recent studies,especially in Baltoscandia and North America.have shown the great value of δ13C chemostratigraphy for clarifying regional and global stratigraphic relationships.In the Upper Ordovician,there are two major global,and now widely documented,δ13C excursions (e.g.,Kaljo et al.,2004；Young et al.,2005；Bergstr(o)m et al.,2006),the early Katian Guttenberg excursion (GICE) and the Himantian excursion (HICE).Between the GICE and the HICE,three,or four,positive δ13C excursions have been recognized in Estonia (Kaljo et al.,2004；Ainsaar et al.,2004a) but their extra-Estonian geographi crange has remained unknown.