TY - JOUR A1 - Vavrdova,M. T1 - Proterozoic acritarchs from the Precambrian-Cambrian transition in southern Moravia (Menin-1 borehole, Czech Republic) JF - Bulletin of Geosciences JA - Bull. Geosci. Y1 - 2008 VL - 83 IS - 1 SP - 85 EP - 92 CY - Prague PB - Czech Geological Survey SN - 1803-1943 (online), 1802-6222 (print) AV - Free KW - Vendian KW - acritarchs KW - basal clastics KW - southern Moravia AB - Well preserved and varied sphaeromorphs, filamentous trichomes and synaploid organic-walled microfossils occur in fine-grained clastics in the Menin-1 borehole. Thirty genera with 40 species have been identified, previously known from Meso- and Neoproterozoic sediments. The Proterozoic microfossils are excellently preserved, not affected by post-diagenetic thermal alteration. The Vendian age is documented by the presence of the taxa Bavlinella faveolata (Shepeleva) Vidal, 1976, Chabiosphaera bohemica Drabek, 1972, Obruchevella valdaica (Shepeleva ex Aseeva) Jankauskas et al., 1989, Podolina minuta Hermann in Timofeev et al., 1976, and Primoflagella speciosa Gnilovskaya, 1983. The palynological residuum contained no acritarch species of Early Cambrian age, although the basal Cambrian Asteridium tornatum-Comasphaeridium velvetum palynozone was ascertained from 266 m below the level with acritarchs. Thin sections from the Menin-1 borehole suggest a possible presence of more than 600 m of Vendian sediments. Irrespective of the possible secondary origin of the recovered microfossils, the existence of extensive Proterozoic marine sedimentation within the southern part of the Brunovistulicum is clearly demonstrated. Sediments from the Precambrian-Cambrian transition were not subjected to Cadomian or younger metamorphic processes. ER -