Litologia i stratygrafia osadów najwyższego mastrychtu w okolicy Lublina i Chełma

Abstract

W odsłonięciach mastrychtu górnego na Wyżynie Lubelskiej stwierdzono występowanie warstwy glaukonitowej. Scharakteryzowano występującą w niej mikrofaunę oraz przedstawiono wyniki badań petrograficznych i litologicznych. Omówiono profil litostratygraficzny mastrychtu górnego i zwrócono uwagę na wartość korelacyjną warstwy glaukonitowej przy ustaleniu granicy mastrychtu i dano-montu.

LITHOLOGY AND STRATIGRAPHYOF THE UPPERMOST MAESTRICHTIAN DEPOSITS FROM THE LUBLIN AND CHELM AREAS

The paper presents the characteristics of some localities of the uppermost Maestrichtian with horizons of sedimentary scouring. The Cretaceous and Dano-Montian boundary layers axe cropping out in the vicinities of Skrzyniece – Chmiel village in central part of the Lublin Highland. Scoured surface of limestones and opokas is covered by marly opoka enriched in glauconite and yielding accumulations of phosphatic nodules and characterized by mass occurrence of valves of Chlamys acuteplicata A l t h, belemnite rostra and serpulid tubes. This horizon yields microfaunal assemblage of the Early Paleocene character which is mainly characterized by the presence of such forms as Anomalina acuta P I u m m e r and Cibicides lectus V a s s i l en k o. The glauconite layer is overlain by Paleocene gaizes.

The sedimentary break is also found in other part of the Highland, in the vicinities of Chełm Lubelski. Sedimentary scouring horizons were reported from old exploitation of diatomaceous earth at Lechówek and the vicinities of Stawska Góra, Janów and Ochoża. A sedimentary break with characteristic glauconite horizon is marked in the uppermost Maestrichtian opokas at Lechówek. The opokas are generally decalcified· and strongly enriched in glauconite which occurs in streaks or nests. Fragments of white opoka without glauconite, occurring in this horizon, result in breccia-Iike structure of the rocks.

The scoured surface of Upper Maestrichtian marls is overlain by a layer of decalcified glauconite-opal rock 10 cm in thickness and intensively green in colour in the vicinities of Stawska Góra and Janów.

The glauconite layer from the vicinities of Stawska Góra and Janów appears to be of ;the Latest Maestrichtian age.

It is difficult to establish the number of glauconitite horizons from the Chełm Lubelski area on the basis of . all the geological data available. Presumably there are two such horizons: one in the uppermost Maestrichtian and another in the Dano-Montian.