Najnowsze profile podłoża cechsztynu w północno-zachodniej Polsce

Abstract

NEW SECTIONS OF THE ZECHSTEIN SUBSTRATUM IN NORTH-WEST POLANDSummaryThe paper presents new sections of the Zechstein substratum deposits that occur in the western part of the Polish Baltic sea, shore (North-West Poland, Fig. 1).In the bore hole Kamień, albite porphyrites of Lower Permian age were encountered data depth of 2722,3 m. Drilling was, however, completed after piercing a 90 m. thick interval of the rocks considered. The section reflects a continuation of the zones of great thickness of sedimentary series, and of effusive rock covers of Lower Permian age, known also to occur in the southern areas of Rügen, and in the north-eastern part of Mecklenburg.A series of Upper and Middle Devonian deposits was pierced in the bore hole Gościno, beginning from a depth 3304 m. Thickness of this series amounts to about 1100 m. At the top, the series consists of grey-red limestones that contain intercalations of marly claystones, which overlie grey-red marly shales locally with nodules and limestone interbeddings . At the bottom from a depth of 4140 m. it is built up of dark-grey, marly shales. The Devonian series dips under an angle of 0°–10° and rests on phyllitized grey, micaceous schists with the Tentaculites fauna, and with intercalations of quartzite sandstones, also resting horizontally.They are thought to be of older Palaeozoie age.Upper, Middle and probably part of Lower Devonian deposits, encountered in the bore hole Jamno 1 at a depth of 1692 m., are characterized by a development different from that at Gościno: their thickness is approximately 1055 m. At the top, the section consists of marine, calcareous-marly series with coral fauna; the series alternate with continental, arenaceous-siltstone-claystone, mostly variegated members, which in turn are intercalated with quartz conglomerates. At the bottom, beginning with a depth of about 2300 m., the section is represented by continental, clastic, mainly variegated series only. The Devonian rests here almost horizontally.The bore hole Jamno 3 has encountered (from 1987 to 2200 m) and the bore hole Jamno 2 has pierced (1929–2094 m) some complexes of analogous clastic, variegated deposits referred to Lower Devonian. In both sections the deposits dip under an angle of 5°–25°. Primarily, the Devonian deposits extended far more to the north and east.In the bore hole Jamno 2 the Devonian deposits rest with a sharp, angular unconformity, on a series of graptolite shales of Caradoc–Llandeilo age. In this series, the dips vary considerably (20°–90°), some local foldings occur (Table I, Fig. 2), and rocks are strongly slickensided, at places. The Ordovician series was not pierced, although an interval of about 500 m. was drilled. Of similar tectonical character are Ordovician graptolite shales encountered at a depth of 2747 m. in the bore hole Jamno 1. An opinion has been accepted that both series are an evidence of the existence of a Caledonian ridge (marginal area of a miogeosynclinal zone and its foreland) that is thought to run from the south-eastern area of Poland towards North Rügen. According to this interpretation, the older Palaeozoic deposits encountered at Gościno, should represent a more internal zone of the Caledonian ridge.In the bore hole Ustronie, clastic and variegated deposits, probably of Lower Namurian age were encountered at a depth from 3105,6 to 3180,6 m. The deposits are intercalated with thin laminae of limestones.The Upper Carboniferous (Mamurian?) paralic series built up of grey sandstones that contain intercalations of dark shales with flora and fauna remains encountered in the bore hole Koszalin at an interval from 2339 to 3012 m., has not, however, been pierced through. Dip angle of this series amounts to 15°–30°.