Dedolomityzacja utworów dolomitu płytowego na wyniesieniu Łeby

Abstract

DEDOLOMITIZATION OF PLATY DOLOMITE ZECHSTEIN ROCKS IN THE ŁEBA ELEVATION AREA Summary Platy Dolomite rocks are strongly dedolomitized in area of the Łeba Elevation. The share of calcite is varying from 20 to 100%. The dedolomitization resulted in alternating and usually irregular occurrence of rocks of the dolomite-limestone transitional series. This process was mainly connected with changes in structure of single dolomite crystals and texture of rocks, leading to omnipresence of mosaic of fine- and coarse-crystalline calcite. The coarse-crystalline calcite preferentially occurs in lower, mudstone part of the Platy Dolomite succession. The dedolomitization appears the least advanced in biolaminoids formed in the sabkha system. Sandy carbonate rocks of the marginal zone are characterized by advancement of dedolomitization changes farly easy correlate with identified sedimentary cycles. Such dependence, however, cannot be found in the vast sabkha area. The major role in origin of dedolomitic calcite was• played by dedolomitization proceeding under surface or subsurface conditions and related to temporary subformational and, subsequently, postformational exposure of sedimentary cover. It may be assumed that mudstone facies rocks from lower parts of the Platy Dolomite section were dedolomitized due to processes acting at some depths.