Prawidłowości występowania strontu w gipsach mioceńskich południowego obrzeżenia Gór Świętokrzyskich

Abstract

REGULARITIES OF STRONTIUM DISTRIBUTION IN MIOCENE GYPSUM SOUTH OF THE HOLY CROSS MTS (CENTRAL POLAND) Summary South of the Holy Cross Mts (Fig. I), the gypsum sequence is composed of different lithofacies which form a succession of eighteen layers, from a to r (Fig. 2). Geochemical data show distinct variations of Sr concentration between 179 ppm and 3915 ppm (average 1022 ppm Sr) (Table, Fig. 2, 3). The highest Sr content was recorded in skeletal and sabre-like gypsum varieties (1512 ppm and 1340 ppm Sr). In other lithofacies, average values do not exceed 1200 ppm. The lowest concentration was found in gypsarenites, bedded selenites and microcrystalline (alabastrine) gypsum (801 ppm, 872 ppm, and 914 ppm Sr, respectively). A variable Sr content is proved within giant gypsum intergrowth and single selenitic crystal. A vertical distribution of strontium throughout the section is not uniform (Fig. 2, 4). Sr concentration decreases toward the top of the sequence. The highest Sr content was recorded in layers o and h (1896 ppm, 1823 ppm Sr). Cyclic sequence of lithofacies is expressed by a vertical distribution of strontium (Fig. 2). A horizontal distribution of strontium is characterized by a distinct decrease of concentration and more homogenous values toward the marginal parts of the sulphate platform (Fig. 5). These results provide arguments for unstable salinity conditions during the gypsum formation in the peripheral part of the Badenian basin.