By comparison with the Lower Cretaceous of central and SE Poland, that of NW Poland (the Pomeranian, Szczecin, and Mogilno-Łódź troughs) has scarce biostratigraphic data. But, despite the lack of Lower Cretaceous exposure in the NW Polish Lowlands, borehole data, including borehole-cores and geophysical logs, allow analysis of complete successions. We refine the stratigraphic units using parallel studies of ammonites, microfauna and calcareous nannoplankton collected from the same intervals, and by correlating age-defined intervals with geophysical logs. Ostracod zones F to A are documented by the presence of ostracod assemblages representing the interval between the Upper Tithonian (ostracod zone F) and the lower part of the Upper Berriasian (ostracod zones E to A). The fragmentary and poorly preserved ammonites allowed only for distinguishing the uppermost Middle and Upper Berriasian (Ryazanian), while the informal subdivisions from the central part of the basin could not be identified unequivocally. Nannoplankton recognized in the succession analysed was very rare due to shallow marine facies of the strata. Only one nannoplankton zone was recognized in the lower part of the succession studied: the CC2 Stradneria crenulata Zone (uppermost Middle and Upper Berriasian and lowermost Valanginian). An additional study only on nannoplankton enabled recognition of certain boreal taxa typical of the BC2 zone of the Uppermost Riazanian. Valaginian ammonites occur in core material located closer to the central part of the trough. Some planktonic foraminiferal species indicate the Lower Aptian. Some Upper Cretaceous nannoplankton zones were also recognized: the CC9 Eiffellithus turriseiffeli (Uppermost Albian to Lower Cenomanian) and UC0, UC1-2 and UC3 zones which correspond to the Upper Albian and Lower as well as Middle Cenomanian. The sequence stratigraphic interpretation was based on geophysical logs with the application of gamma-ray, neutron-gamma, spontaneous potential and resistivity logging, as well as caliper logging. These studies allowed recognition and correlation of sedimentary sequences within the part of the sedimentary basin analysed, characterized by a similar cyclic pattern of geological phenomena described using depositional sequences as in the central and SE part of the Polish Basin. Third-order depositional sequences with maximum flooding surfaces were distinguished. Effective correlation of depositional cycles with biostratigraphy and with the global sea level curve was demonstrated for several boundaries, confirming the applicability of this method for the Polish part of the the Central-European Basin. Other boundaries recognized that are not correlatable and shifted relative to Haq’s curve may reflect autogenous factors (e.g., local tectonics) overlapping with the global changes controlled by allogenic processes



中文翻译：

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波兰中海槽西北段下白垩统生物地层学和层序地层学

与波兰中部和东南部的下白垩统相比，波兰西北部（波美拉尼亚、什切青和莫吉尔诺-罗兹槽）的生物地层数据稀少。但是，尽管波兰西北部低地缺乏下白垩统暴露，但钻孔数据，包括钻孔岩心和地球物理测井，可以分析完整的演替。我们使用从相同间隔收集的菊石、微型动物和钙质超微浮游生物的平行研究，并通过将年龄定义的间隔与地球物理测井相关联，来细化地层单元。介形类动物区 F 至 A 由代表上提通阶（介形类动物区 F）和上贝里亚阶下部（介形类动物区 E 至 A）之间的间隔的介形类动物组合的存在来证明。零碎且保存不佳的菊石仅允许区分最上层的中贝里亚和上贝里亚（梁赞），而盆地中部的非正式细分无法明确识别。由于地层的浅海相，在所分析的演替中发现的微浮游生物非常罕见。在所研究的演替的下部只发现了一个超微浮游生物区：CC2Stradneria crenulata带（最上面的中部和上部 Berriasian 和最下面的 Valanginian）。一项仅针对超小型浮游生物的额外研究能够识别某些典型的梁赞最上层 BC2 带的北方分类群。Valaginian 菊石出现在靠近槽中央部分的核心材料中。一些浮游有孔虫物种表明下阿普蒂安。一些上白垩纪超微浮游生物区也被识别：CC9 Eiffellithus turriseiffeli（上阿尔比阶到下塞诺曼阶）和 UC0、UC1-2 和 UC3 带，对应于上阿尔比阶和下以及中塞诺曼阶。层序地层解释基于地球物理测井，应用伽马射线、中子伽马、自发电位和电阻率测井，以及卡尺测井。这些研究允许对所分析的沉积盆地部分内的沉积序列进行识别和关联，其特征在于使用沉积序列描述的地质现象的类似循环模式，如在波兰盆地的中部和东南部。区分了具有最大泛滥面的三级沉积序列。几个边界证明了沉积旋回与生物地层学和全球海平面曲线的有效相关性，证实了该方法对中欧盆地波兰部分的适用性。其他公认的与 Haq 曲线不相关和偏移的边界可能反映了与异源过程控制的全球变化重叠的自生因素（例如，局部构造）