Terreneuvian acritarch assemblages of the Holy Cross Mountains : a new approach

Rock samples from four boreholes and three exposures located in the southern peripheries of the Holy Cross Mountains in Poland, from strata representing the lower Cambrian Czarna Shale Formation have been studied palynologically. A relatively numerous and well-preserved lowermost Cambrian microfloral assemblage corresponds to coeval associations known from different palaeocontinents. Our new data enables reinterpretation of the biostratigraphy of the Czarna Formation, a thick rock unit basically devoid of macrofossils. The rocks analysed represent the Terreneuvian and comparison with other lower Cambrian successions indicates the middle and upper part of this oldest Cambrian series. The discovery of Variosphaeridium gen. nov. supplements information about the diversity of lowermost Cambrian microfloral assemblages. The Fimbriaglomerella membranacea–Globosphaeridium cerinum Assemblage Zone is introduced; it has a transitional character between the Asteridium tornatum–Comasphaeridium velvetum and Skiagia ornata–Fimbriaglomerella membranacea assemblage zones distinguished by Moczydłowska (1991) and identified on most Cambrian palaeocontinents.