Devonian Siliciclastic Rocks of the Babí Lom Locality (Southern Moravia, Czech Republic): Sedimentary Environment Reconstruction and Provenance Study

Abstract

De vo nian siliciclastic rocks of the Babí lom lo cal ity (south ern Moravia, Czech Re pub lic): sed i men tary en vi ron ment re con struc tion and prov e nance study Jurand Anchimetamorphosed sand stones and con glom er ates of the so-called "Basal De vo nian Clastics", that build a hill (ridge) named Babí lom, are con sid ered to be of Lower to Mid dle De vo nian age. Al though they are strongly tec toni cally af fected, many sed i men tary fea tures are well-pre served and dis tinct. Both the fa cies and struc tures typ i cal of al lu vial fans and rivers were rec og nized in the sed i men tary as so ci a tion at Babí lom. Among oth ers, there are chan nel lags with imbricated grains, cross-bed ding, and debrites. The way-up di rec tion is clearly seen via re pet i tive coars en ing-up wards se quences. As sum ing a lack of ro ta tion of the suc ces sion in the X-Y plane, the main palaeodrainage was to wards the north and the ma jor sup ply of ma te rial was from the east. The high ma tu rity of the rocks sug gests der i va tion from older de pos its and/or highly weath ered source rocks. The mag matic rocks of the Brunovistulicum are pos si bly the pri mary source of the sed i ments.Key words: south ern Moravia, Brno Mas sif, De vo nian siliciclastics, fa cies anal y sis, heavy min er als, al lu vial fan. INTRODUCTIONIn Czech geo log i cal lit er a ture, the term "Basal De vo nian Clastics" is used for the red monomictic quartz-peb ble conglom er ates, quartz arenites, subarkoses, and ar kos es with interbeds of lam i nated siltstone, as well as for polymict conglom er ates which are ex posed in sev eral ar eas of south ern Moravia (e.g., Dvoøák, 1978, 1998Gilíková, 2007). These depos its have also been named the Old Red Sed i ments (Skoèek, 1980;Zukalová and Chlupáè, 1982). The best known oc currences of these clastics are in the Moravian Karst area, between Bílovice nad Svitavou and Ochoz u Brna (Gilíková et al., 2010), in the Babí lom -Èervený kopec Zone be tween Svinošice and Lelekovice, and in the Èebínka Zone near the town of Tišnov (Hanžl et al., 2007). These rocks are also known from nu mer ous deep bore holes along the south east ern mar gin of the Bo he mian Mas sif (Vavrdová et al., 2003;Mikuláš et al., 2008).Spec tac u lar out crops of De vo nian clastic rocks in the Babí lom des ti na tion (Fig. 1) have at tracted the in ter est of a num ber of in ves ti ga tors (Dvoøák, 1960;Melichar et al., 1999;Nehyba et al., 2001;Gilíková, 2007;Buriánek et al., 2008). The aim of this pa per is to pres ent re sults of sedimentological and pet ro graph ical stud ies car ried out in sev eral iso lated ex po sures in this zone, that ad dress the ques tions of: -depositional pro cesses and set tings, -evo lu tion of the depositional en vi ron ment, -source ar eas, -and dem on strate ap pli ca bil ity of sedimentological techniques in tec toni cally de formed coarse clastic. GEOLOGICAL SETTINGThe siliciclastic sed i men tary rocks of the Babí lomÈervený kopec Zone crop out over the N-S elon gated area bordered ...

Depositional environment and provenance of the Gresten Formation (Middle Jurassic) on the southeastern slopes of the Bohemian Massif (Czech Republic, subsurface data)

“…For simplification the abbreviation GF will be used herein for the Gresten Formation. The basement of the GF is mostly formed by Paleozoic deposits (Cambrian-Carboniferous) (Kalvoda et al, 2008;Vavrdová et al, 2003;Nehyba et al, 2001;Wojewoda et al, 2015) in the Nesvačilka paleovalley and Nikolcice-Kurdejov ridge areas, and by the crystalline basement of the Brno Massif in the area west of this ridge.…”

Sedimentological study of the Nikolčice Formation - evidence of the Middle Jurassic transgression onto the Bohemian Massif (subsurface data)

“…The base ment of the area un der study is formed by a com plex of Cadomian magmatic rocks known as the Brno Mas sif, which is over lain by Paleo zoic, Me so zoic and Ce no zoic de pos its. The sed i men ta tion be gan by very lim ited (within the north ern part of the study area) Cam brian basal clastic de pos its (Jachowicz and Pøichystal, 1997;Vavrdová et al, 2003), which are fol lowed by basal clastic de pos its of De vo nian age (Nehyba et al, 2001;Wojewoda et al, 2015). How ever, as the li thol ogy of these two units is very sim i lar, it is lo cally dif fi cult to dis tin guish be tween them with out micropalaeontological in for ma tion.…”

Devonian Sedimentary Rocks Tectonically Incorporated Into the Brno Massif, Eastern Margin of the Bohemian Massif

“…In-tercalation of strong conglomerates and soft sandstones and siltstones leads to zonal geomorphology with rocky ridges separated by smooth terrain. Petrography of Babí lom zone clastic rocks was described by Zádrapa (1962) and sedimentary interpretation by Wojewoda et al (2015). The age of these sedimentary rocks was considered to be lower Devonian (Zapletal 1931(Zapletal -1932.…”