Wskaźnik mineralogiczno-petrograficzny przeobrażenia skał ilastych w warunkach epigenetycznych

Abstract

MINERALOGICAL-PETROLOGICAL INDEX OF CLAY ROCK ALTERATION UNDER EPIGENETIC CONDITIONS

Summary

Clay minerals occurring in sedimentary rocks are the most finely grained components and the most susceptible to physical and physico-chemical conditions along with the geological time. Analysis of variation of clay minerals may facilitate attempts to reconstruct conditions under which alteration of sedimentary series of our interest took place in previous geological epochs. Alterations of clay mineral assemblages resulting from epigenetic processes are of remarkable interest as they are accompanied by changes in cooccurring organic matter. Characteristics of a given sedimentary series often cannot be based on products of alteration of organic matter, as the products may be missing in results of migration processes. In such case clay minerals occurring in sedimentary series may be used as indices for reconstructing ancient geological processes. Studies on regularities in distribution Off day minerals were carried out in order to distinguish and delineate zones liable to have an accelerated mobility of bitumens, and first of all to undergo a higher degree of metamorphism of organic matter occurring in Early Paleozoic strata of the Peribaltic syneclize. Analyses of composition of clay minerals stressed the importance of the degree of crystallinity of illite. The present author used crystallinity index suggested by Weaver (1960) and Kübler (1964). However, the results obtained inclined the author to introduce certain modification of that index: The index of illite crystallinity used by the present author is obtained from the following formula: maximum height of basic reflex 001 / width of basic reflex 001 measured at its mid-height. The two variables were obtained for all the samples studied under exposition and recording conditions constant.