Inkluzje mikroorganizmów w kryształach badeńskich gipsów Przedkarpacia

Abstract

INCLUSIONS OF MICROORGANISMS IN THE MIDDLE MIOCENE BADENIAN GYPSUM CRYSTALS OF THE CARPATHIAN FOREDEEP Summary Crystalline gypsum is characteristic of the Middle Miocene Badenian in the Carpathian Foredeep of southern Poland and West Ukraine (Fig. 1). A rhythmic zonality of gypsum crystal growth is caused by occurrence of mineral, fluid, and micro-organic inclusions (Fig. 2). Study of fluid inclusions and analyses of water extracts showed that brines during deposition had sulphate composition. Solutions in inclusions are saturated in respect to gases related to degradation of organic matter. Figs 3 and 4 show examples of micro-organic inclusions. Besides of common algae, also representatives of higher organisms were found. Good state of preservation of the microorganism tissues indicates anaerobic conditions during gypsum precipitation. The micro-organic inclusions contain organic fluids in addition to water solutions. It is clear that brines in the Badenian basin at the time of gypsum deposition were saturated in respect to calcium sulfate, however, it was found that the total mineralization during deposition of skeletal and sabre-like gypsum in Borków did not exceed 0.5 %. Earlier the mineralization ranging from 1 to 9% was recorded in different parts of the Badenian basin [9, 16] based on the study of fluid inclusions. The conclusion is that the total mineralization of the Badenian basin was a few times lower than that characteristic of the stage of gypsum precipitation from marine-derived brines (i.e. 11- 12 % ). An alternative may be that the studied inclusions are not primary but according to OIP and AWP, there are no features indicating such a possibility. OIP and AWP thank to International Science Foundation for the Grant No. UCM 000.