Górna jura w obrzeżeniu Gór Świętokrzyskich

Abstract

UPPER JURASSIC IN THE MARGIN OF THE ŚWIĘTOKRZYSKIE MTS Summary The present opinions on the Upper Jurassic of the margin of the Świętokrzyskie Mts. are given briefly, and the exposures of the Upper Oxfordian ("Astartian") and Lower Kimrneridgian found in the north-eastern area of the margin are discussed. The Lower Oxfordian: Divesian and Neuvizyan, is faunistically evidenced in the north-eastern and south-western margin areas, the Middle Oxfordian: Argovian, too. The deposits of the Upper Oxfordian - "Rauracian" and "Astartian" - developed as sponge limestones, and bank and coral limestones, disclose ample fauna of sponges, corals, brachiopods and pelecypods, at places of cephalopods, particularly in the north-eastern area of the margin, and so far have not been evidenced by ammonite fauna. In the Upper Oxfordian quarries at Błaziny (2 km south of Iłża, south-eastern margin of the Świętokrzyskie Mts.) a complex occurs of "Astartian" deposits, characterized by its special development. These are formations of atypic reef. Here are found anthozoans and oolies in compact, oolitic, chalky and detrital limestones, light grey and cream-coloured. Characteristic fauna assemblage consists of thick-shelled pelecypods (Diceras, Eodicras, Plesiodiceras), gastropods (Nerinea, Nerinella), and brachiopods. In these deposits are found two horizons of flints, a part of which being syngenetic, others epigenetic. The Kimmeridian marIs and marly limestones, with intercalations of lumachelles and shell limestones, are evidenced by ammonite fauna. In the north-eastern margin are found deposits of the whole Lower Kimmeridgian, partly of the Upper Kimmeridgian, immediately covered with the Valanginian formations. Góra Zamkowa at Iłża reveals, at exposures, the Lower Kimmeridgian formations, immediately above the horizon Pictonia baylei. These are marts and marly limestones, light grey and cream-coloured, with intercalations of lumachelles and oolite marls. The fauna assemblage consists here of pelecypodos and brachiopods. Epithyris subsella (Leym.) and Epithyris cincta (Cotteau) are abundant, among pelecypods dominate Mythilus (locally in lumachelles), Trigonia, Modiolus acquiplicatus (Sow.) and Nanogira nana (Sow.). In the north-western area of the margin, in the vicinity of Tomaszów, there occurs the whole Upper Kimmeridgian, and its sedimentary continuity with the Portlandian, named by J. Kutek - Volgian, can be observed. Here are found deposits of Lower Portlandian and Middle Portlandian age. The Upper Portlandian deposits developed in Purbeckian facies, are not found in the marginal area of the Świętokrzyskie Mts. The next area of their occurrence is near Przytyk, NW of Radom.