Litologia i stratygrafia utworów trzeciorzędu okolic Jastrzębiej Góry koło Pucka

Michał Marzec, Emil Woźny



Lithology and stratigraphy of the Tertiary from the Jastrzębia Góra and Puck areas, northern Poland, are discussed on the basis of core materials. Cretaceous substrata include Lower Turonian siltstones with Inoceramus labiatus Schloth., Anomalina berthelini Keller, Lingulogavelinella globosa (Brotzen), and others, and Cenomanian quartz-glauconite sands with numerous inoceramids and belemnites. Boreholes have provided almost continuous cores of the Eocene, Oligocene and Miocene. In the Eocene-Oligocene sequence, 5 series are distinguished. Three lowest of these series are paleontologically dated and are of great importance as they represent a new example of the occurrence of these lithostratigraphical units in single vertical profile. The oldest series, commonly 2.0-3.0 m thick, named herein the lower Mieroszyno series, consists of deposits of shallow-water marine facies, such as marly siltstones with glauconite, phosphorites, quartz gravels, and lumps of iron sulphides. Microfaunla assemblage, indicative of Upper Eocene age, comprises such forms as: Cibicides suzakensis Byk., Lenticulina dimorfa Tutk., and Uvigerina costellata Mor. Macrofauna indicating the Bathonian age of these deposits includes pelcypode, Venericardia divergens praeculta (Kluschnikov), and other forms. The next series, a few meter thick and named herein the upper Mieroszyno series, consists of remarkably homogeneous clayey, decalcified siltstones. These strata are indicative of sedimentation under more quiet conditions than those under which the lower Mieroszyno series was deposited. Palynological studies show the latest Upper Eocene age of these strata. The overlying strata, represented by a series of green sand and sandy quartz-glauconite silts with amber and single phosphorites, a few meter thick, are dated on the basis of remarkably richer faunal assemblage. The assemblage comprises such forms as: Cardita latesulcata Nyst., Balanophylia subcylindrica Phillipp, Cyprina cf. perovalis Koenen, Panopea gastaldi Mich., Isocardia multiculcata Nyst., Ceratobulimina contraria Reuss, Lentipecten corneus (Sowerby), and others, indicative of the Lattorfian age. According to the nomenclature proposed herein, the series is named the Połczyno series. Deposits of a successive sedimentary cycle, which presumably is of the Middle Oligocene age, are represented by uniform, homogeneous series of marine grey-green, quartz-glauconite sands, devoid of faunal record. The series is a few meter thick, on the average. The youngest link of the Palaeogene from the area in question is represented by deposits which originated in brackish or marshy environment. These deposits are represented by series of dark-grey clayey silts, horizontally laminated with quartz sand. These silts yield carbonized plat remains and innumerous grains of glauconite. The series is thin and attains a few meters in thickness, on the average. Top parts of the profile in question are represented by deposits of the late Tertiary - Neogene - which originated in land-locked, fresh-water basin. This series, a few tens of meters in thickness, comprises quartz, micaceous thinly-bedded sands and sandy silts with admixture of carbonized plant remains. Upper part of this series, yielding thin beds of brown coals, well-exposed in Chłapowo and Rozewie cliffs, has been assigned to the Lower Miocene on the basis of identifications of flow remains.

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