Problemy rudonośności osadów na tle diastrofizmu i wulkanizmu Gór Świętokrzyskich

Abstract

PROBLEM OF ORE CONTENTS IN SEDIMENTS IN THE LIGHT OF DIASTROPHISM AND VOLCANISM OF THE ŚWIĘTOKRZYSKIE MTS.SummaryThe visible progress in geological investigations on magmatism (also on the present-day volcanism) and on various processes that take place at the boundary of hypergenesis and volcanism force us to pay attention to the depositional aspect of this problem. The works recently carried out in the Świętokrzyskie Mts., have been an initial point for the considerations concerning the relationships between the ore content and the regional diastrophism and volcanism.Volcanic processes are source of a huge amonunt of materials brought in various forms (pyroclastites, hydrothermes, gases) and in various ways into the sedimentary basins. Along with the materials of different origin this material is subject to the laws that govern the processes of sedimentation and diagenesis.In the Świętokrzyskie Mts. the coexistence of ores and volcanic manifestations has been observed to occur in the rock formations of Ordovician, Silurian, Devonian, Carboniferous, Permian and Tertiary age (Figs 3 and 4). This relationship can especially be seen in the Ordovician and Devonian rocks.It results from the regional analysis that transgressive deposits are particularly favourable for the occurrence of Fe, Cu, Pb and Zn ore deposits, as well as Mn, P and Ba ones. They were formed during the extinction phase of tectonic activity as a rule accompanied, within the geosynclinal area, by strong volcanic processes. Mineralization can concern both the sediments formed due to post-orogenic transgression and those of the post-phase ingressions. The deposits were formed under favourable palaeogeographical conditions (morphology, climate, and biogenic factors), supported by the specific development of marine ingressions. An oscillatory course of the transgressions and ingressions made the metal concentration possible, mainly in the sediments laid down during the short periods of changing facial conditions caused either by the stopping or by the weakening in the rate of ingression (Figs 2, 6, 7). Mineralization phenomena and ore deposits produced in this way could be defined as sedimentary-volcanogenic. According to the present authors a lot of ore occurrences found in the Świętokrzyskie Mts. should be related to this group (e.g. Fe-mineralization in the Ordovician formations, and Fe- and Cu-mineralization in the Lower Devonian ones). A part of these deposits most probably represent a "remote" type, formed in the peripheries of the geosynclinal zones, far from the active volcanic centres. Occurrence of Fe, Cu, Pb and Zn accompanied by SiO2, lens-like forms, predominance of sulphide facies, and small reserves – are their characteristic features. Such deposits can be enriched due to the processes related to the later tectonic regeneration, overlapping on the primarily mineralized sedimentary-volcanic series.Conclusions that result from the studies considered can be referred to the entire area of South Poland. All fundamental investigations of deposits and prospecting works should be preceded by a thorough analysis of structural conditions, palaeotectonics, palaeogeography, and magmatic phenomena. To the most promising belong here the transgressive series, particularly the sediments formed during the change in sedimentary conditions. The Lower Wendian, Arenigian-Llanvirnian, Siegenian -Emsian -Eifelian, Rotliegendes-Zechstein, Buntsandstein -Roethian, and. Helvetian-Tortonian sediments are thought to be investigated in the first place.