Podział i charakterystyka litofacjalna górnomioceńskich osadów węglonośnych w odkrywce złoża węgla brunatnego Bełchatów

Abstract

W osadach górnomioceńskich w KWB Bełchatów wydzielono 7 jednostek litofacjalnych. Są to utwory facji jeziornej, bagiennej i rzecznej. Wykazują one cykliczny charakter sedymentacji, na podstawie czego w rowie Kleszczowa wyróżniono 3 cyklotemy węglowe.

SUBDIVISION AND LITHOFACIES CHARACTERISTICS OF UPPER MIOCENE COAL-BEARING ROCKS FROM THE BELCHATOW BROWN-COAL OPEN-CAST MINE

Data gathered in the course of field works in the Belchat6w brown-coal open-cast mine made it possible to compile 6 detailed lithological columns (Fig. 1) of Miocene rocks exposed in exploitation escarpments (western wall, section N -S). Taking into account most characteristic features of the rocks there were differentiated 7 Iithofacies units, denoted with letters A-G: carbonate rocks (A), clayey sapropel coals (B), tuffogemc clays - "tonsteins" (C), earthy-xylith brown coals (D). clayey brown coals -coally clays (E), gray-brown clays (F), and gray sands (G).

Rocks of the above lithofacies belong to the Upper Miocene brown-coal formation which represents an infill of a depressional structure called as the Kleszczow Trough. They represent sedirnents of iacllstrine, swampy, and fluvial facies, and reflect cyclic character of sedimentation, making possible identification of three coal cyc1othems. The cyelicity in sedimentation of Miocene coal-bearing series is explained as mainly due to subsidence (continuous but neither rhythmic nor unifonn subsidence of Kleszcz6w Trough floor in the Cenozoic), compensated by steady accumulation.

The recorded coal cyclothems of the Upper Miocene"'in the Belchatow brown-coal open-cast mine are developed as follows:

-          lacustrine carbonate sediments (lithofacies A) or gray· brown clays (lithofacies F);

-          clayey sapropel coals (lithofacies B) or gray·brown clays (iithofacies F);

-          earthy·xylith brown coals (lithofacies D) or clayey brown coals (lithofacies E).