Abstract—

Data on fossils and stratigraphy of the Bajocian and Bathonian boundary deposits in the north of European Russia recently published by Ippolitov, Zakharov, Kiselev, et al. are discussed. Their previously proposed correlation of the Middle Jurassic reference sections of the Pechora North region on the Dreshchanka River (a tributary of the Izhma River), as a result of which the visible thickness of deposits is doubled, is critically revised. New finds of the ammonite Arctocephalites arcticus (Newton) confirm the biostratigraphic data previously obtained by Mitta et al. The interval with Mezounio zwerkovi and Retroceramus lungershauseni, previously recognized by Zakharov et al., occurs at the visible base of the Sysola Formation immediately below the interval of finds of Arctocephalites arcticus and most likely should be correlated with the uppermost Bajocian, rather than with the lower Bajocian. Meledina’s proposal to transfer the Borealis, Indistinctus, and Pompeckji zones of the Вoreal scale from the upper Bajocian to the lower Bajocian is considered to be unsubstantiated.

中文翻译：

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俄罗斯北欧伊日马河流域巴约阶-巴松阶边界层（中侏罗统）地层学研究

摘要-

最近由 Ippolitov、Zakharov、Kiselev 等人发表的关于俄罗斯欧洲北部 Bajocian 和 Bathonian 边界沉积物的化石和地层数据。进行了讨论。他们之前提出的关于德雷尚卡河（伊日马河的一条支流）上的伯朝拉北部地区的中侏罗世参考剖面的相关性，结果是可见的沉积物厚度增加了一倍，经过严格修订。菊石Arctocephalites arcticus (Newton) 的新发现证实了 Mitta 等人先前获得的生物地层数据。Mezounio zwerkovi和Retroceramus lungershauseni的间隔先前由 Zakharov 等人确认，出现在 Sysola 组的可见底部，紧邻Arctocephalites arcticus发现的间隔下方，很可能与最上层的 Bajocian 相关，而不是与下部 Bajocian 相关。Meledina 将 Вoreal 尺度的 Borealis、Indistinctus 和 Pompeckji 带从上巴约阶转移到下巴约阶的提议被认为是没有根据的。