Systematyzowanie lito stratygrafii jury górnej w Polsce północnej i środkowej

Abstract

Przedstawiono propozycje podziału litostratygraficznego epikontynentalnej jury górnej w obszarze Polski północnej i środkowej, gdzie zaznaczają się trzy regiony litofacjaIne (fig. 1, tab. 4). W ich obrębie proponuje się wyróżnienie dziesięciu formacji. Formacje: I - gąbkowo-wapienna, II - wapienno-marglista, III - koralowcowa, IV - oolitowa i V - wapienno-marglisto-muszlowcowa są rozwinięte w sposób typowy w obszarze południowej Polski i tam zostaną ustanowione ich stratotypy. Dla formacji: VI - łupkowo-marglisto-mułowcowej (pałuckiej), VII - wapienno-ewaporatowej (kcyńskiej), VIII - mułowcowej (Łyny), IX - piaszczysto-chlorytowej (Chociwla) i X - oolitowo-mułowcowej (Brdy) rdzennym obszarem jest obszar północny, gdzie będą ustanowione ich strato typ.SYSTEMATIZATION OF IJTHOSTRATIGRAPHY OF THE UPPER JURASSIC IN NORTHERN AND CENTRAL POLANDThe works on systematization of lithostratigraphic subdivisions of epicontinental Upper Jurassic of Poland were undertaken by the team of geologists of the Geological Institute, Warsaw University and Petroleum Industry. Two working groups were created: one for the southern Poland, leaded by J. Kutek, and other for the central and northern, leaded by J. Dembowska.Sixteen formations are proposed for the whole epicontinental Upper Jurassic of Poland. Six of these, the Urzędów, Jarczew, Tyszowiec, Ruda Lubycka, Zakrzew and Babczyn Formations, differentiated by T. Niemczycka (1976b) in the Lublin area, are characteristic of the southern Poland only.The other seven formations occur in both areas. Five of them have been described for the first time from the southern area and their stratotypes will be selected there: I - spongy-limestone, II - limestone-marly, III - coral, IV - oolitic, and V - limestone-marly-siltstone formations. The Formations I, IV and V were also discussed in detail as the Kraśnik, Bełżec and Głowaczów Formations of the Lublin region by T. Niemczycka (1976b) but they should be redefined as they also occur in other regions of the southern area. The remaining two of these Formations, VI - shale-marly-siltstone (Pałuki) and VII - limestone-evaporitic (Kcynia) Formations, have been described for the first time from the northern area.The remaining of the 16 Formations, VIII - siltstone (Łyna), IX - sandy-chlorite (Chociwel), and X - oolite-siltstone (Brda) Formations are confined to the northern area and their stratotypes will be selected there.The paper presents lithostratigraphic subdivision proposed for the northern region (Table 4). Three regions may be differentiated here with reference to character of rocks (Fig. 1). The region I comprises south-eastern part of that area (Fig. 2, Table 1), where lower part of Upper Jurassic section comprises shallow-water limestones, and the upper - marly-clay deposits. Formations differentiated in that section except for its uppermost part are those of the southern area. The region 11, situated north-west of the former, is characterized by predominance of siltstone and marly-clay rocks (Fig. 3, Table 2). The region Ill, comprising the most north-western part of Poland, is characterized by predominance of shallow-water, sandy and oolitic deposits in lower part of the section (Fig. 4, Table 3).