大兴安岭中北部晚侏罗世—早白垩世地层新认识

New idea of Late Jurassic-Early Cretaceous strata in the north-central Da Hinggan Mountains, China

根据大兴安岭中北部地区晚侏罗世火山岩正常沉积夹层中所含叶肢介化石的研究成果和同位素年龄新资料,认为大兴安岭北部西坡被归入白音高老组中的“含Eosestheria的酸性、酸碱性火山碎屑岩和熔岩”不是白音高老组,应归入龙江组,层位与辽西义县组对比。大兴安岭主脊火山岩(满克头鄂博组、玛尼吐组、白音高老组)从南到北是同期火山活动作用的结果,不存在“穿时”现象,形成于晚侏罗世早中期,层位与冀北大北沟组对比。

According to the study of Estheria contained in an interbed of ordinary sedimentary rocks of the Late Jurassic volcanic rocks in the north-central Da Hinggan Mountains and new isotope age data,the authors consider that the ＂Eosestheriabearing acid and acid-alkaline pyroclastic rocks and lavas＂ assigned to the Baiyingaolao Formation on the western slope of the northern Da Hinggan Mountains should be assigned to the Longjiang Formation and its horizon may correlate with the Yixian Formation in western Liaoning. The volcanic rocks （Manketou Obo Formation, Manitu Formation and Baiyingaolao Formation） in the main ridge of the Da Hinggan Mountains are the result of the contemporaneous volcanic activity from south to north and there exists no diachronous phenomenon. They formed in the early-mid Late Jurassic and their horizon may correlate with that of the Dabeigou Formation in northern Hebei.