Badania geochemiczne cechsztynu z rejonu syneklizy perybałtyckiej

Abstract

GEOCHEMICAL RESEARHES OF THE ZECHSTEIN DEPOSITS FROM THE PERIBALTIC SYNECLISE AREA

Summary

To obtain geochemical information on the sedimentary conditions of the Zechstein deposits, the occurrence of numerous trace and secondary elements within the area of the Peribaltic syneclise was considered.
Geochemical characteristic of the material taken from five drill sections in study was made with the aid of the following chemical elements: Cu, Pb, Zn, Ni, Co, Mo, V, Cr, Ba, Sr, Ti and Mn.
The results of the ·examinations have shown that a general tendency exists to increase the concentration of certain chemical elements, such as Cr, V, Ba and Ti, characterized by a restricted ability of migration in the Upper Zechstein clayey deposits found in the peripheral zones of the sedimentary basin. A distinct increase in strontium concentration was observed in a direction from arenaceous-clayey deposits towards carbonate and sulphate ones (Fig. 1). An increase of these latter is, in all probability, of biogenic character. Moreover, certain regularity in the arrangement of strontium concentration in the section has also been observed. This element shows its lowest concentrations in the middle series of the carbonate deposits, in the main dolomite horizon. Its contents are higher in the lower and upper parts of the section, i.e. in the deposits of the Werra (Ca₁) dolomite and of the plattendolomit (Ca₃ – Fig. 4). A differentiation of Sr frequency in the deposits of the main dolomite horizon (Fig. 10) was probably caused by the later processes during the diagenesis period, in which most of dolomitization processes took normally place.
The main dolomite horizon is characterized by a small range of results, and by average Cu, Pb, Mo, V, Cr, Ba, Ti and Fe contents, lower than in the main dolomite, and by a higher Sr content that corresponds to the Werra carbonate horizon (Figs. 1–6). This regularity appears almost throughout the entire area of the Peribaltic syneclise.
A multimodal distribution of frequency of chemical elements, observed in most cases points to several stages in the process of their accumulation and, most probably, is an evidence of a heterogeneous form of their supply to the sedimentary basin (various compounds and various minerals).