Dedolomityzacja utworów górno jurajskich w okolicy Hedwiżyna (płd. Lubelszczyzna)

Andrzej Gąsiewicz

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DEDOLOMITIZATION OF UPPER JURASSIC ROCKS IN THE VICINITIES OF HEDWIŻYN, SOUTHERN LUBLIN REGION

Summary
Upper Jurassic limestones from the borehole Hedwiżyn- 2 (southern Lublin region) display several features indicative of dedolomitization. Dedolomitization is shown here by marked changes in structure of crystals (from unchanged dolomite through gradual degradation of its crystalline form and complete obliteration in calcareous groundmass to crystallization of calcite and, finally, origin of polycrystalline aggregate of the latter). This process also affected dolomitic groundmass, leading to formation of two types of rocks: fine-crystalline and coarse-crystalline ones as well as dedolomitization of previously dolomitized ooids.
The dedolomitization was soon followed by solution of calcite which resulted in marked increase in porosity of the rocks. In the Hedwiżyn area, dedolomitization processes appear related to post-Late Jurassic uplift in the Lublin region and migration of dedolomitizing solutions downwards, mainly along numerous small-scale tectonic discontinuities.

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