O procesie dehydratacji gipsów w zapadlisku przedkarpackim
Abstract
ON THE DEHYDRATATION PROCES OF GYPSUMS IN THE CARPATHIAN FOREDEEP
Summary
The article discusses the problem of the genesis of the anhydrites found to occur in the northern and central parts of the Carpathian foredeep, and formed after the alteration of gypsum due to the secondary diagenetic and recrystallization-dehydratation changes. Tectonic activity of dynamometamorphic type in the zones of dislocations or in the adjacent areas also strongly affected all these processes. Observations of drill cores demonstrate that the sulphate deposits encountered in the Carpathian foredeep are represented by three varieties intertonguing with each other, depending upon the amount of crystallization water and occurrence depth. 1. Gypsums are found to occur at an uppermost level, from 0,00 to 250-300 m. They are characterized by a type macrocrystalline texture in the lower part of the section, and by lamellar structures in the upper part. 2. Dehydrites occur at a depth of 250-500 m. 3. Anhydrites make the third variety of the sulphates and occur at a lowermost level, at a depth from 500 to 2500 m, except for the areas situated near the dislocations, where the anhydrites are found at a lesser depth. Within the three intertonguing zones of sulphate occurrences are found two series which can be correlated lithologically. The similarity consists in the development of similar structures in the upper laminar series, as well as in the presence of some structures after the altered recrystallized selenites in both dehydrites and anhydrites of the lower series.
Summary
The article discusses the problem of the genesis of the anhydrites found to occur in the northern and central parts of the Carpathian foredeep, and formed after the alteration of gypsum due to the secondary diagenetic and recrystallization-dehydratation changes. Tectonic activity of dynamometamorphic type in the zones of dislocations or in the adjacent areas also strongly affected all these processes. Observations of drill cores demonstrate that the sulphate deposits encountered in the Carpathian foredeep are represented by three varieties intertonguing with each other, depending upon the amount of crystallization water and occurrence depth. 1. Gypsums are found to occur at an uppermost level, from 0,00 to 250-300 m. They are characterized by a type macrocrystalline texture in the lower part of the section, and by lamellar structures in the upper part. 2. Dehydrites occur at a depth of 250-500 m. 3. Anhydrites make the third variety of the sulphates and occur at a lowermost level, at a depth from 500 to 2500 m, except for the areas situated near the dislocations, where the anhydrites are found at a lesser depth. Within the three intertonguing zones of sulphate occurrences are found two series which can be correlated lithologically. The similarity consists in the development of similar structures in the upper laminar series, as well as in the presence of some structures after the altered recrystallized selenites in both dehydrites and anhydrites of the lower series.