Tremadok Lubelszczyzny

Abstract

Przedstawiono wstępne rezultaty badań piaskowcowo-ilastych i węglanowych utworów trema doku Lubelszczyzny, które zostały stwierdzone w profilach otworów wiertniczych wykonanych w latach 1968 - 1976 przez Instytut Geologiczny i Zjednoczenie Górnictwa Naftowego. Zamieszczono zwięzły opis ich litologii, podano typową sekwencję zespołów skalnych oraz przeprowadzono podział stratygraficzny, wyróżniając utwory tremadoku dolnego (pakerort A_II) i tremadoku górnego ceratopyge A_III). Część końcowa artykułu zawiera omówienie problematyki facjalnej, uwagi paleogeograficzne oraz porównania z równowiekowymi utworami obszarów sąsiednich: obniżenia podlaskiego,·zapadliska przedkarpackiego oraz południowo-wschodniego przedłużenia Gór Świętokrzyskich.

THE TREMADOCIAN OF THE LUBIJN REGION

In the Lublin region, Tremadocian rocks were found in several boreholes. They overlay uneven erosional surface of Middle Cambrian substratum and they are overlain by transgressive Lower Arenigian (Latorp B_I) rocks overstepping them. The Tremadocian vary in thickness from 0.1 to 40.5 m, as well as in its development. Sandy-clay deposits generally predomina1e here. In some sections, carbonate intercalations may be found in upper part d the sandy-clay deposits.

The Tremadocian rock complex displays bipartity in age. Its lower part represents time equivalent of the Lower Tremadocian (Pakerort All)' and the upper - supposed equivalent of the Upper Tremadocian (Ceratopyge A_III). The paleontological record d these rocks is poor as there were found only some inarticulate brachiopods Obolus cf. apollinis E i c h w a I d, Obolus sp. and Lingulella sp., crustaceans Phyllocarida and hardly identifiable graptolite and ostracode remains. Of these, only  Obolus cf. apollinis E i c h w a I d is of some stratigraphic value as that species is widely recognized as indicative of the Lower Tremadocian, i.e. Pakerort A_ll.

Tremadocian rocks of the Lublin region display a marked differentiation in the regional pattern which makes possible to distinguish three lithofacies zones: external - conglomeratic-sandstone, transitional - conglomeratic-clay, and internal - conglomeratic-sandstone clay with carbonates. The first zone represents external parts d the epicontinental basin, comprising areas of a wide shelf plain, whereas the remaining two zones were situated in more internal part of the basin, the sedimentary environment of which corresponded to proximal part of continental slope descending to the west .

The present extent of Tremadocian rocks is not original, being related to denudational processes from the turn of the Tremadocian and Arenigian as well as to late-epigenetic erosion from the Late Paleozoic times.