Osady ordowiku na wyniesieniu Łeby

Zdzisław Modliński




In the Łeba elevation area the Ordovician deposits have been encountered in four bore holes: Lębork IG 1, Żarnowiec IG 1, Łeba 8 and Smołdzino 1. Small thicknesses and a distinct predominance of clayey deposits over carbonate deposits point to a fact that in the area of study the Ordovician belongs to the so-called Scanian facial zone distinguished by R. Männil (1966). Sedimentation begins here with the formations of the Lower Arenigian, laid down on the Upper Cambrian deposits, and terminates with the uppermost Ashgillian. The Lower Arenigian is represented by a series of dark claystones subdivided into the following graptolite zones: Tetragraptus phyllograptoides, Didymgraptus balticus, Phyllograptus denesus, Phyllograptus angustifolius elongatus. The Upper Arenigian discloses pelitic limestones with Megistaspis limbata (B o e c k) and Sumphysurus palpebrosus D a l m a n. Llanvirnian is built of pelitic limestones, locally nodular, with Asaphus rainceps D a l m a n at the bottom and Neoasaphus cf. platyurus latisegmentatus (N i e s z k.) at the top. In the Llandeilian there are found mixed clayey-marly deposits with the fauna represented by Glyptograptus teretiusculus (His.) and Trinucleus bronni (S a r s et Boeck). Caradocian is represented by a clay series including the following graptolite zones: Nemagraptus gracilis, Diplograptus molestus, Climacograptus wilsoni, Dicranograptus clingani and Climacograptus styloideus.The Lower Ashgillian is built of clayey formations that disclose representatives of Tretaspis granulata (Wahl.), and the Upper Asgillian – of marly limestones marls and marly claystones with Dalmanitina mucronata (Brongn.). In the Łeba elevation area, the total thickness of the Ordovician formations, measured in the so far examined bore hole profiles, amounts to 47 m in bore hole Smołdzino l, increasing in bore hole Żarnowiec IG 1 to 76,8 m.


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