Petrografia szkliwa wulkanicznego z iłów bentonitowych z miejscowości Ciecierze koło Chmielnika

Abstract

PETROGRAPHY OF VOLCANIC GLASS IN BENTONITE CLAYS FROM CIECIERZE NEAR CHMIELNIK (SOUTHWARD FROM THE ŚWIĘTY KRZYŻ MTS.)Within the scope of geological studies carried out in the area of Chmielnik by the Petroleum Institute and the Main Laboratory of the OH Industry at Cracow, the author collected in 1957, for purposes of petrographical investigation samples of bentonite clays.These bentonites belong to tuffogenic deposits; their sedimentation took place in the Tortonian (S. Alexandrowicz, W. Parachoniak, 1956).In this exposure we may distinguish two bentonite intercalations, extending in a complex of dark-grey bentonite clays of about 15 m. thickness, one of white, the other of yellow colour. By differential thermal investigations the author established the fact that these beds correspond to montmorillonite (Fig. 1).The volcanic glass isolated from this clay consists of globular and obsidian forms; as to its chemical composition it contains a fairly large amount of FeO, Fe2O3, CaO and MgO, with a marked content of SiO2 and Al2O3 (see Polish text, Table 2).The bentonite from the Chmielnik area was produced by weathering. of tuffogenic material. The chemical character of the magma corresponds to that of andesite magma (see Polish text, Fig. 1).