黑龙江东部侏罗—白垩系界线附近地层研究新进展

<正> 近年来,随着饶河东安镇具国际性对比标准的海相侏罗—白垩系界线的确定及其相关生物组合带的建立(孙革等,1989),黑龙江省东部地区的海相—海陆交互相—陆相的侏罗—白垩系界线及其附近地层的研究,不断取得新的进展。研究成果之一是,鸡西盆地城子河组时代属早白垩世。在其典型剖面(穆棱河北岸路堑剖面)的城子河组下部,发现含早白垩世凡兰吟—戈特里夫期(Valanginian-Hauterivian)沟鞭藻的海相层(孙学坤、

Recent advance in the research of the strata near the Jurassic-Cretaceous boundary in eastern Heilongjiang

The finding of the new marine beds with Valanginian-Hauterivian dinoflagellates intercalated in the lower Chengzihe Formation and the new discovery of the earliest angio-sperm megafossils from the upper part of the formation, made recently by the authors, have shown the geological age of the Chengzihe Formation as early-middle Early Cretaceous, approximately corresponding to Berriasian (Ryazanian)-Hauterivian(or to early Barremian). The biozones represented by Buchia of the Donganzhen Formation are revised by the authorsas following: B,-B. pacifica (L. Valanginian), B3-B. volgensis-B. cf. okensis-B. cf.subokensis-B. unschensis (Ryazanian-E. Valanginian), B2-B. fischeriana-B. unschensis (L.Volgian), B,-B. russiensis-B. fischeriana (M. Volgian). The J-K. boundary (i. e. betweenthe B2 and B3) is redefined as that lower for 4.9m than before and with the first occurrence of B. cf. subokensis as the lowest Lower Cretaceous (i. e. the Upper Subformation of Donganzhen Fm). The geological ages of the "Shihebei Fm", Dongrong Fm and the Longzaogou Group are also discussed.