Sinian i paleozoik z otworu wiertniczego Jaronowice IG-1

Abstract

SINIAN AND PALAEOZOIC IN THE BORE HOLE JARONOWICE IG-ISummaryThe bore hole Jaronowice IG-1 made in 1965 yielded interesting materials (concerning both geological structure and tectonics of the Pre-Mesozoic substratum in the Nida trough. The following are deposits found in this bore hole immediately under the Muschelkalk, at the depths from 1826,0 to 2630,0 m (Fig. 2). From 1826,0 to 1958,2 m there occur Middle Devonian (Eifeilian) deposits represented at the bottom by dolomites with siltstone intercalations  brown-cherry,  or green in colour. Below (from 1914,5 to 1958,2 m), there are found dark-grey limestones with a dolomite layer at the base, representing an equivalent of the Dąbrowa zone examined by D. Sobolew (1909) in the area north of Kielce. The following fauna has been distinguished here: ChonetesaugustestriataGürich, SpiriferdormbrowiensisGürichand TentactilitespolonicusGürich. At the depths from 1958,2 to 20371,5 m, there are Lower Devonian (Emsian(?) deposits developed as sandstones, quartzites and variegated siltstoneslacking fauna, and containing tuffite intercalation. From 2037,5 to 2068,5 m deposits of problematic age (Silurian? Lower Devonian) have been encountered. There are siltstoneswith sandstonesintercalationat the top, and conglomeratic at the bottom. From 2068,5 to 2275,0 m, Lower Siluriandeposits occur represented by Wenlockian and Llandovery. They are developed as shale-like claystones with intercalation of arenaceouslimestones and of black lydite. Graptolite fauna is abundant (Fig. 3). At the depths from 2275,0 to 2288,8 the Ordovician (Upper Tremadocian) deposits are represented by sandstonesand glauconite siltstoneswith Lingulellalepis (Salter). From 2288,8 to 2630,0 m, there occur Upper Sinian consisting of claystones and siltstones with calcareous sandstone and quartzite intercalation. Most probably these deposits are equivalents of the Bug beds, according to the nomenclature of J. Znosko (1965).Both Paleozoic and Sinian deposits pierced at Jaronowice disclose certain considerable stratigraphical breaks that are an effect of structural processes. Here, no rocks younger then Eifelian, and older than  Muschelkalk, have been encountered. Greeat breaks are found at the Devonian-Silurian boundary, and transmission deposits are lacking between the  and Tremadocian. Cambrian and Lower Tremadocian formations have not been ascertained too.Considering the section investigated at Jaronowice in the light of the geological structure of the southern area of a Pre-Cambrian and Old-Paleozoic geosyncline, in which orogenic deformations have taken place twice, at least i.e. as Sandomirian and as Young Caledonian movements. Probable parageosynclinal  development o the Young Paleozoic sedimentary cycle ended in Hercynian deformations, maybe at the time of Erzgebirge phases.