CAMBRIAN SILICICLASTIC SEDIMENTS (CZECH REPUBLIC) 67
LOWER CAMBRIAN SILICICLASTIC SEDIMENTS
IN SOUTHERN MORAVIA (CZECH REPUBLIC)
AND THEIR PALEOGEOGRAPHICAL CONSTRAINTS
and SLAVOMÍR NEHYBA
Institute of Geology, Academy of Sciences CR, Rozvojová 135, 165 02 Praha 6, Czech Republic; firstname.lastname@example.org;
Department of Geology and Paleontology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic;
(Manuscript received April 11, 2002; accepted in revised form October 3, 2002)
Abstract: Petrological, sedimentological and ichnological studies of cores from the Měnín-1 borehole revealed episodic
shallow marine influence in the terrestrial clastics underlying the Devonian clastic and carbonate rocks. The organic-
walled, acid-resistant microfossils have been recovered from bioturbated beds and have allowed us to determine the age
as the earliest Cambrian (most likely Platysolenites antiquissimus Faunal Zone). Several index acritarch species justify
a preliminary assignment to the Asteridium tornatum—Comasphaeridium velvetum Acritarch Zone. The microfossils are
very well preserved, without any noticeable thermal alteration (thermal alteration index about 1+) or mechanical dam-
age. The ichnoassemblage contains Diplocraterion isp., Skolithos isp., and Planolites isp. The intensity of bioturbation
and ichnofabric patterns correspond well to those described from the Cambrian of the East European Platform. The
composition of Cambrian acritarch assemblages, of the ichnotaxa, as well the very low thermal alteration of organic-
walled microfossils, link this Moravian sedimentary cover of Brunnia (Brunovistulicum in broader sense of the mean-
ing) to the sediments of the same age which rest on other crustal segments in the southern and central part of Poland and
even further on the Baltica Paleocontinent. This indicates a connection rather than separation of these Cambrian
“Gondwanan parts” and Baltica by the Trans-European Suture Zone.
Key words: Early Cambrian, paleogeography, sedimentology, ichnofossils, acritarchs.
Clastic sediments which underlie the Moravian platform car-
bonates have been penetrated by numerous deep boreholes,
most of them drilled by the Moravian Oil Mines, Hodonín
(Zádrapa & Skoček 1983). These sediments were informally
called the “basal clastics” by Zapletal (1922) and subsequently
by other authors. Because of the specific position at the con-
tact of three major orogens of Europe, their origin is signifi-
cant for the understanding of the pre-Variscan development of
Central Europe. Their terrestrial nature, lack of fossil remains,
and unmetamorphosed appearance led the previous authors
(Skoček 1980; Dvořák 1998) to assign the basal clastics to the
Devonian, initiating the Paleozoic sedimentary succession in
Moravia. However, Roth (1981) suggested the Cambrian age
of the so-called “basal clastics” on the basis of their similarity
to paleontologically dated Cambrian sediments in SE Poland
(Orłowski 1975, 1985).
The most complete succession of the basal clastics has been
recovered in the Měnín-1 borehole situated about 15 km
south of Brno (Fig. 1). The present report deals with segments
of the cores from the borehole, which are housed in the Mora-
vian Oil Mines Company Hodonín. The previous study by
Fatka & Vavrdová (1998) dealt with microfossil content of a
single sample from the uppermost parts of the basal clastics in
the Měnín-1 borehole, while the present study extends the pa-
leontological (ichnofossils, palynomorphs) and sedimentolog-
ical studies. The depositional environment, biostratigraphy
and paleogeographic interpretation are synthetized. Only in-
complete small relics of the drill cores (cores 19-33B from
depths between 655.0 m and 2042 m) were available for the
Zádrapa (1975) and Skoček (1978) started the petrological
studies of Paleozoic rocks of the Měnín-1 borehole. Otava (in
Skoček 1978) and Zádrapa (1975) investigated heavy miner-
als. Skoček (1980) and Skoček & Zádrapa (1983) subdivided
the sedimentary fill of the borehole into two units, both miner-
alogically mature (Maštera 2000). A content of feldspar is typ-
ical for the lower unit, whereas the upper unit is formed by
monomictic-quartzose rocks. Dvořák (1998) subdivided the
lower unit into two parts. The basal part consists mostly of
coarse-grained poorly sorted subarkoses with beds and lenses
of fine-grained conglomerates. The upper part consists mostly
of sorted and unsorted, fine-grained and medium-grained, sub-
arkoses and quartzose sandstones.
Bioturbation of sedimentary rocks of the Měnín-1 borehole
was observed by Skoček (1980) and described as “vertical
shafts filled with a substance of different grain size”. In the
previous, more detailed manuscript, Skoček (1978) stated that
bioturbation was generally quite frequent in the Měnín-1 bore-
hole, and a single type of vertical to oblique passages or tun-
GEOLOGICA CARPATHICA, 54, 2, BRATISLAVA, APRIL 2003
67 — 79
nels was present. However, no systematic ichnology was pro-
posed. The first ichnological study of the rocks was presented
by Mikuláš & Nehyba (2001).
Palynological investigation of selected samples of the basal
clastics provided data for an unequivocal assignment of some
siliciclastic sequences underlying Moravian carbonates to the
Early Cambrian as suggested by Roth (1981). These results
were published by Jachowicz & Přichystal (1997), Vavrdová
(1997a), Fatka & Vavrdová (1998), and Vavrdová & Bek
(2001). At present, fossiliferous samples of the Early
Cambrian age are known from three boreholes: the Měnín-1
borehole (Fatka & Vavrdová 1998), Němčičky-3 borehole
(Jachowicz & Přichystal 1997; Vavrdová & Bek 2001) and
Němčičky-6 borehole (Vavrdová 1997a; Jachowicz & Přichys-
tal 1997). The bed of fine laminated silty mudstone/shale with
Cambrian acritarchs (core 16, depth 473.0—477.5 m) in the
Měnín-1 borehole belongs to the basal part (“pelitic
formation”) of the upper unit (Skoček 1980; Zádrapa 1975).
Finds of palynomorphs significantly improved the age
assignment, facies interpretation and paleogeography of the
basal clastics. In additional to the recognized alluvial deposits,
coastal sabkhas and ephemeral lakes of tropical climate
(Skoček 1980; Zádrapa & Skoček 1983; Dvořák 1998), the
presence of shallow marine environment is indicated by the
Several lithofacies have been recognized within the studied
cores (Fig. 2). Sandstones strongly dominate in the studied
samples. They are mostly classified as quartzose ones. Subar-
koses, arkosic and graywacke sandstones were also recog-
nized. Quartz grains totally dominate the sandstones. Their
rounding varies between individual samples from subangular
or angular to rounded. The latest are quite frequent. Grains of
monocrystalic quartz predominate over polycrystalic ones.
The occurrence of feldspar grains is relative low, from 5 % to
20 %, rarely about 30 %. Orthoclases usually dominate over
plagioclases. The content of micas (both muscovite and bi-
otite) is highly variable. The finer sandstones have a relatively
higher proportion of unstable grains, predominantly of acidic
plagioclases, than the coarse-grained sandstones.
Fragments of pegmatites and older sandstones were rarely
recognized. Grains of stable rocks, mostly silicites or quartz-
ites are rare. Zircone, apatite, tourmaline and garnet grains are
present as accessories. The content of sandstone matrix is be-
low 10 %. Clay minerals, sericite and chlorite dominate in the
matrix. Carbonate matrix is very rare.
Quartz grains predominantly angular and subangular form
also the dominant part of the mudstones. High presence of mi-
cas is typical for the mudstones. Muscovite dominates over bi-
otite. Feldspar grains are relatively rare. The matrix is clayey
with an important content of hematite.
Planar cross-bedded sandstones form this lithofacies. It was
recognized in the cores 19, 29, 30, 31A, 32, and 33B. Both
small-scale ripple cross bedding, with the set thickness of
about 5 cm, and large-scale cross bedding, with set thickness-
es of tens of centimetres, are present. Reactivation surfaces
and sigmoidal bases of laminae are common.
The colour of the sandstones is highly variable, from light
green to green-grey, light and dull red-brown, grey, and violet.
It is controlled by variations in the content of hematite, grain-
size or intensity of silicification. Alternations of horizons of
slightly coarser and finer grains are typically reflected in alter-
nation of lighter and darker colours.
Grain size of sandstones is highly variable, from fine to very
coarse. The very coarse sandstones can sometimes be in tran-
sition/association with lithofacies Gp. Both relatively well-
sorted and poorly sorted samples were observed. Coarser
grained sandstones are commonly poorly sorted, especially
because of the presence of outsized clasts, mostly of quartz.
These clasts can be classified mostly as granules, which are 5
to 15 mm in size. Clasts of quartzite, feldspar, granitoid, silic-
ite, quartzose sandstone and mudstone intraclasts are both
subordinate and smaller. Intraclasts up to 7 mm in diameter
occur. The outsized clasts are commonly subangular and often
form thin laminae.
Trough cross-bedded sandstones form this lithofacies. They
were recognized in the cores no. M-1A and 26A. Small-scale
ripple trough-cross bedding is typical. Bedding planes are ir-
regular and the boundaries of sets are erosive.
The colour of the sandstones is light green-grey or red-
brown. Alternation of laminae of slightly finer (also darker)
and coarser (also lighter) grains makes the bedding distinct.
Fig. 1. The sketch/map of Central Europe showing the location of
CAMBRIAN SILICICLASTIC SEDIMENTS (CZECH REPUBLIC) 69
Fine-grained beds are also characterized by a higher content of
micas (especialy biotite) and hematite. The content of hema-
tite increases especially in the matrix.
The sandstones are fine- to coarse-grained and relatively
poorly sorted. Especially coarse-grained sandstones are char-
acterized by the presence of outsized clasts up to 4 mm in di-
ameter. Locally recognized thin intercalations of mudstones in
sandstones reflect the transition/association of facies St and H.
The lithofacies is formed by a massive sandstone and was
recognized in the core no. 27. Intensive silicification obscured
probable primary sedimentary structures.
The sandstone is medium- to fine-grained, green grey co-
loured and relative well sorted. Quartz and feldspars are the
dominant grains. Micas are rare.
Parallel-laminated sandstones form this lithofacies. They
were recognized in the cores no. 21 and no. 23. Horizontal to
low angle lamination occurs. Rhythmic alternation of distinct
lighter and darker laminas is connected with several factors,
such as locally relatively common occurrence of micas (both
biotite and muscovite) with iron oxides and hydroxides or al-
ternation of sandstone and mudstone laminae (rhythmites).
The occurrences of often bioturbated mudstone laminae reflect
the transition/association of the facies Sl and H.
The sandstones are fine- or medium-grained. The fine-
grained sandstones are micaceous. Grey or red-brown colours
are the most typical.
Lithofacies H is characterized by heterolithic bedding,
where sandstone beds alternate with mudstones. This facies
was recognized in the cores nos. 20B, 23, 27A, 29, 30, and
M-1A. The thickness of individual beds varies from several
milimetres up to several centimetres. Lenticular, flaser or
wavy bedding, based on the relative abundance of sandstones
and mudstones occurs. The dominance of sandstone over
mudstone is more common. Bedding planes with load or
Fig. 2. Fragments of drill cores showing the characteristic lithofacies. 1 – Lithofacies Gp (core no. 33B); 2 – lithofacies SP (core no. 19);
3 – sharp contact of lithofacies Gp and Sp; 4 – lithofacies H (core 21); 5 – lithofacies Sl (rhythmite, alternation of sandstone and mud-
stone laminae, core no. 29).
flame structures are typical. Bioturbation is relatively com-
mon. Transition/association of facies H to facies Sl or Sr can
sometimes be recognized.
Sandstones are usually light grey, red-brown to violet in co-
lour. Ripple cross-bedding is common, whereas horizontal
lamination is rare. Grain size of sandstones is variable, mostly
fine to medium. Micaceous, coarse- and very coarse-grained
sandstones, with outsized grains up to 0.5 cm in diameter are
also recognized. Mudstone intraclasts, up to 10 mm in diame-
ter, occur locally. Sorting of the sandstones varies from rela-
tively good to poor.
Mudstones (micaceous siltstone to silty claystone) are typi-
cally pale green grey, dark grey and dark red brown in colour.
Sandy siltstones occur locally with the higher presence of mi-
cas. Horizontal stratification together with preferred orienta-
tion of micas is common.
Granule-sized conglomerates, massive, horizontally strati-
fied to cross-bedded were observed in the cores no. 27A, 29,
32, and 33B. The conglomerates display sharp contacts with
The conglomerates are red to pink-violet in colour. Quartz
granules and pebbles up to 8 mm, but 2.5 mm in average di-
ameter are dominant. The quartz is pink, brown yellow,
brown, light green and grey in colour. The quartz clasts are
rounded to subrounded and very similar to the quartzes ob-
served in the sandstones. Granules of quartzites, feldspars and
mudstone intraclasts are rare. Intraclasts are up to 5 mm in di-
ameter. Granules and pebbles of stable minerals and rocks
represent about 97—98 %. Medium-grained quartz sandstone
forms the matrix.
Interpretation of the lithofacies
The lithofacies Sp, Sr and Gp can be explained as products of
the tractional currents. They are produced by migration of
both relatively low bedforms (ripples) and bars. The existence
of larger foresets is problematic. Rapid and probably episodic
migration of bedforms led to the formation of sharp and often
erosive contacts between sets or lithofacies. There is no direct
evidence of wave or tidal action.
The lithofacies Sl reflects relatively rapid flow (upper
flow regime) and episodic deposition. Lithofacies H is also
connected with episodic deposition and relatively flat bed-
ding planes. In this case, deposition from relatively rapid
tractional currents alternated with relatively quieter periods.
The quieter periods of deposition were suitable for biotic
colonization. Moreover, fine-grained sediments (mudstones,
siltstone, very fine-grained sandstones) are both mineralogi-
cally and texturally more mature than coarse-grained ones.
This can be explained by multiple source and variations in
transport. Sole marks reflect the plastic consistence of the
sediments. It is important that all trace fossils and microfos-
sils occur in the lithofacies H. The lithofacies H is associated
with facies Sr and Sl.
Trace fossils occur in a few samples (cores no. 20B, 21, 27A,
29 and M-1A ) only in lithofacies H (heterolithic bedding).
Diplocraterion Torell, 1870
M a t e r i a l : About twenty horizontal and vertical cross-
sections of biogenic structures were found in a 7 cm long core
sample of grey micaceous siltstone from the Měnín-1 bore-
hole, at the level of 1565—1566 m. A dozen shorter, less con-
spicuous structures were found at the depth of 856.2 m in
dark-grey to light-grey laminated siltstones to sandstones.
D e s c r i p t i o n : The ichnofossils have the appearance of
10—25 mm long and 3—5 mm wide bars on bedding planes.
The bars show widened terminations, interpreted as sections
of vertical tubes. Vertical sections of the ichnofossils are
Fig. 3. 1, 2 – Diplocraterion isp.: The Měnín-1 borehole, interval 1565.0—1566.0 m. The core diameter is 9 cm.
CAMBRIAN SILICICLASTIC SEDIMENTS (CZECH REPUBLIC) 71
perpendicular or nearly perpendicular to the bedding, with
vertical extent is 15—35 mm, show a meniscate lamination
(spreiten-structure). The filling of the biogenic structures is
lighter and composed of sandy matrix. The samples from the
depth of 866.2 m clearly show that the infilling comes from
the overlying bed; the same has been observed in the sample
from the level 1565.0—1566.0 m.
R e m a r k s : The ichnofossils can be interpreted almost
certainly as U-shaped vertical “limbs” each connected with a
lamina of reworked sediment, that is spreite and classified as
Diplocraterion isp. (e.g. Fürsich 1974; Häntzschel 1975;
Fillion & Pickerill 1990) Diplocraterion represents dwelling
burrows of filter feeders, typical of high energy depositional
Planolites Nicholson, 1879
M a t e r i a l : One specimen in a sample from the depth of
776.0—778.0 m. Several cross-sections of tunnels in a sam-
ple from the depth of 1298.0 m.
Fig. 4. 1, 4, 5 – Skolithos cf. linearis Haldemann, 1840; 1, 5: The Měnín-1 borehole, interval 776.0—778.0 m; 4: Měnín-1 borehole
1370.5 m; 2, 3 – Planolites isp.: The Měnín-1 borehole at the depth of 1298.0 m. The core diameter 9 cm.
D e s c r i p t i o n : Subhorizontal tunnels, circular to ellipti-
cal in outline, filled with material contrasting with the sur-
rounding rock. Tunnel diameter is 2—6 mm; observable seg-
ments are short but probably exceeding several centimetres
R e m a r k s : Ichnotaxonomic determination of the trace
fossils follows the paper by Pemberton & Frey (1982). Plano-
lites is usually interpreted as a trace of sediment feeding or a
locomotion in-fauna trace.
Skolithos Haldemann, 1840
Skolithos cf. linearis Haldemann, 1840
M a t e r i a l : Several tens of vertical shafts or their sec-
tions from the Měnín-1 borehole, depth 776.0—778.0 m;
1370.5 m; and 1565.0 m samples.
D e s c r i p t i o n : Circular cross-sections of vertical shafts,
usually 2.5—4.0 mm in diameter. One sample (1350.5 m)
shows at least three larger cross-sections, reaching 8, 12 and
16 mm in diameter. Vertical aspect of the trace can be ob-
served in only one of the samples (Fig. 4.4).
R e m a r k s : For the systematic ichnology of Skolithos
see, for example, Osgood (1970), Alpert (1974, 1975), Fil-
lion & Pickerill (1990). Most of Skolithos are interpreted as
dwelling burrows of filter feeding organisms.
The ichnoassemblage consists of ichnotaxa with wide strati-
graphic ranges. The ichnogenera Diplocraterion, Planolites
and Skolithos are known from Proterozoic to Recent sedi-
ments. Nevertheless, the ichnofossils enable us to interpret
certain parameters of sedimentary settings. The Cambrian bio-
turbation is generally considered to be quite different from the
rest of the Phanerozoic; recently, the term “Cambrian sub-
strate revolution” was introduced (Bottjer et al. 2000; Dorn-
bos & Bottjer 2000). The “pre-revolutionary phase” is charac-
terized by a low quantity and shallowness of bioturbation of
soft bottoms. In contradiction to the theory, however, relative-
ly strongly bioturbated (but not repeatedly mixed) siltstones
and sandstones bearing the Diplocraterion and Skolithos ich-
nofabric were described from the Lower Cambrian of the East
European Platform sediments (e.g. Lendzion 1972). Pacześna
(1996, 2001) distinguished several assemblages of trace fos-
sils from the paleontologically well-dated Cambrian strata of
eastern Poland. The ichnoassemblages described by this au-
thor, including Skolithos, Monocraterion, Bergaueria and Pla-
nolites are very close to the ichnofossils recognized in the
Měnín-1 borehole in the ethological and environmental sense
as well as in the lithology of host substrates.
The Cambrian ichnological record is limited almost exclu-
sively to shallow sea. The only Cambrian assemblage that has
been interpreted as brackish is very specific in its composition
(cf. Mikuláš 1995). The described ichnofossils and the spec-
trum of their ethological functions points to origins in shallow
marine settings with high dynamics of sedimentation and ero-
sion. We may also identify the “kraksten-structure” of Eastern
Europe (e.g. Lendzion 1972) and the Diplocraterion ichno-
fabric from the Měnín borehole.
Prokaryotic filamentous and coccoid cyanobacteria, fungi,
eukaryotic algal planktonic microfossils (acritarchs and prasi-
nophytes), algal sheats, metazoan fossil remains, fragments of
algal tissues have been recorded in the fine-grained portions
of subsurface clastic sediments in the boreholes SE of Brno,
between Brno and Hodonín. Microfossils were studied in per-
manent strew slides (Fig. 8) and thin sections, as well as by
scanning electron microscopy (SEM; Figs. 5—7). The Lower
Cambrian palynomorph assemblages from southern Moravia
reflect the increasing diversity of planktonic eukaryotic pro-
tists following the Vendian/Cambrian transition (Vidal &
Moczydłowska 1992; Moczydłowska 1999). Two main types
of fossil assemblages have been distinguished: the upper
Lower Cambrian (Holmia/Protolenus) diversified associa-
tions, recovered in the Němčičky-3, Němčičky-6 and in the
upper part of Měnín-1 borehole, depth 473.0—477.5 m (25
genera and 53 species) and basal Cambrian assemblages of
low density and low diversity (11 genera and 16 species), iso-
lated from the bioturbated sequences in the lower part of
Měnín-1 borehole (depth 1565.0—1566.5 m and 865.2 m). The
upper Lower Cambrian samples from boreholes Němčičky-3
and Němčičky-6 yield assemblages dominated by acantho-
morphic types of acritarchs, especially of genus Skiagia
Downie, 1982. Planktonic microfossils display various elabo-
rate means to enlarge vesicle surface such as long tubular pro-
cesses (Fig. 5.3), irregularly branched (Fig. 5.4), distally ex-
panded (Fig. 6.1) or connected (Fig. 6.4) or provided with
outer membranes enveloping the central body (Fig. 7.1). Most
common are the following species: Skiagia sp. indet. aff. S.
compressa (Volkova) Downie, 1982 (Fig. 6.1,2; Fig. 7.3);
Skiagia scottica Downie, 1982 (Fig. 6.3,4), Skiagia ciliosa
(Volkova) Moczydłowska, 1991 (Fig. 5.1,2); Skiagia ornata
(Volkova) Downie, 1982 (Fig. 5.3). The late Early Cambrian
age is documented by the presence of species Vogtlandia
yankauskasii (Fensome et al.) Sarjeant et Vavrdová, 1997
(Fig. 5.4), Estiastra minima Volkova, 1979 (Fig. 7.4), Saga-
tum priscum (Kirjanov et Volkova) Vavrdová et Bek, 2001
(Fig. 7.1) and others.
Investigations of samples from the levels 856.2 m (core
number 21) and 1565—1566.5 m (core number 29) in the
Měnín-1 borehole revealed the presence of evidently much
older assemblages of palynomorphs. Palynological residuum
contained well preserved, but sparse acritarchs and prasino-
phytes of low diversity and filamentous sheats of presumed
cyanobacterial origin. Ribbon-shaped, irregularly twisted and
folded, compressed filamentous sheets occur relatively fre-
quently in the palynological residuum (Fig. 8.12). They are
characterized by having a smooth surface and elastic wall of
light to dark yellow colour. Acritarchs are dominated by leio-
spheres and forms with inconspicuous ornamentation of vesi-
cle surface, such as low grana, solid thorns and short hairs
(Fig. 8). Rarely present are tasmanitids (Fig. 8.3), fragments
CAMBRIAN SILICICLASTIC SEDIMENTS (CZECH REPUBLIC) 73
Fig. 5. SEM image JEOL, Němčičky-3 borehole, at the depth 5396.0 m. 1, 2 – Skiagia ciliosa (Volkova) Downie, 1982; 3 – Skiagia
ornata (Volkova) Downie, 1982; 4 – Vogtlandia yankauskasii (Fensome et al.) Sarjeant et Vavrdová, 1997.
of relatively large-sized, possible Neoproterozoic phytoplank-
ton (cf. Tanarium), fragments of hydrozoan stolons, various
tissues and unidentifiable fragments. The following species
have been identified so far: Archaeotrichion spp. (Fig. 8.12),
Asteridium lanatum (Volkova) Moczydłowska, 1991, A. tor-
natum (Volkova) Moczydłowska, 1991 (Fig. 8.12), A. sp. in-
det., Comasphaeridium agglutinatum Moczydłowska, 1988,
Comasphaeridium molliculum Moczydłowska et Vidal, 1988
(only at the depth 865.2 m), C. velvetum Moczydłowska,
1988 (Fig. 8.11), Leiosphaeridia sp. (Fig. 8.1), Leiovalia ten-
era Kirjanov, 1974, Lophosphaeridium bacilliferum Van-
guestaine, 1974 (Fig. 8.2,4,6), Lophosphaeridium tentativum
Volkova, 1968, L. sp. indet, aff. L. truncatum Volkova, 1968
(Fig. 8.5,7), ?Myxococcoides staphylidion Lo, 1980 (only at
depth 856.2 m), Pterospermella velata Moczydłowska, 1988
(only at depth 865.2 m), aff. Tanarium sp. indet. (Fig. 8.10),
aff. Tasmanites tenellus Volkova, 1968 (Fig. 8.3), and Cer-
atophyton vernicosum Kirjanov in Volkova et al., 1979.
Fragments of microfossils provisionally assigned to
Neoproterozoic large-sized process-bearing acritarchs (aff.
Tanarium) were ascertained in the Měnín-1 borehole samples.
So far they have been reported from the Khamaka Formation
(Vendian to Cambrian) of eastern Siberia (Yakutia, Nepa
Botuoba region) and Ediacaran Pertatataka Formation, Ama-
deus Basin, Australia (Moczydłowska et al. 1993).
Interpretation of palynomorphs
Age correlations are based on palynozones established by
Moczydłowska (1991) within Early Cambrian subsurface suc-
cessions in SE Poland (Lublin Slope). The presence of index
species A. tornatum and C. velvetum as well as an absence of
species frequent in younger Cambrian zones allows us to as-
sign the sample from the depth of 1565.0—1566.5 m to the As-
teridium tornatum—Comasphaeridium velvetum Acritarch
Zone, as defined by Moczydłowska (1991) from southeastern
Poland. This zone, contemporaneous with the oldest skeletal
fauna, corresponds to the basal, lower Lower Cambrian or to
the “Lontova horizon” in EEP (Volkova et al. 1983; Moczyd-
łowska 1991, 1988; Vidal & Moczydłowska 1992) and to the
Mazowsze Formation and uppermost part of the Włodawa
Formation in the Lublin Slope, Poland. The assemblage re-
covered from the depth of 856.2 m is distinguished from the
lower level by the presence of the species Comasphaeridium
molliculum Moczydlowska et Vidal, 1988, which, according
to Moczydlowska (1991), appears in the subsequent Skiagia
ornata—Fimbriaglomerella membranacea Acritarch Zone.
However, other species, typical for the Skiagia/Fimbriaglom-
erella Zone, have not been recorded in the assemblage. There-
fore, the age assignment of the upper sample is determined as
early Early Cambrian. The substance of acritarch vesicles, not
affected by thermal alteration, precludes involvement in meta-
Interpretation of depositional environment
The interpretation of depositional environment based on
lithofacies study alone is limited, mostly because of the highly
insufficient amount of cores available for sedimentological
study (about 10 m) compared to the total thickness of the
studied sediments (more than 1500 m). Facies associations
were in such a case very difficult to establish.
Previous authors, who had the possibility to study the com-
plete core material, can add some additional data. The majori-
ty of the studied deposits lack any visible bedding according
to previous authors (Dvořák 1998; Skoček 1980; Zádrapa
1975). Cross-bedding was described as relative common.
Trough cross-bedding predominates and was characterized as
small- or medium-scale one. Horizontal stratification and
grain-size grading are rare. Erosional contacts of beds are
common (Zádrapa & Skoček 1983). Facies from the Měnín-1
borehole significantly differ from those recognized in Brno –
Červený kopec Hill (Nehyba et al. 2001). Cathodolumines-
cence studies confirm these differences (Leichmann & Nehy-
The studied drill cores show a mixture of terrestrial and ma-
rine influences. Previous authors (Dvořák 1998; Skoček
1980; Zádrapa & Skoček 1983, etc.) interpreted an exclusive-
ly terrestrial environment. Indeed, the most often recognized
facies (Sp, Sr, Gp) fits in well with alluvial or fluvial environ-
ments. However, trace fossils can help in tracing marine influ-
ences in the depositional environment (cf. Reading 1996).
Trace fossils not only helped us to identify and interpret the
sedimentary environment, but also to define the interaction
between the biotic assemblage and the abiotic factors of the
environment. It is also necessary to bear in mind that sedi-
Fig 6. SEM image JEOL, the Němčičky-3 borehole at the depth of 5396.0 m. 1, 2 – Skiagia sp. indet. aff. S. compressa (Volkova)
Downie, 1982; 3, 4 – Skiagia scottica Downie, 1982.
CAMBRIAN SILICICLASTIC SEDIMENTS (CZECH REPUBLIC) 75
Fig. 7. SEM image JEOL, locality Němčičky-3 borehole, depth 5396.0 m. 1, 2 – Sagatum priscum (Kirjanov et Volkova) Vavrdová et
Bek, 2001; 3 – Skiagia ciliosa (Volkova) Downie, 1982; 4 – Estiastra minima Volkova, 1979.
mentary processes and environments may have been very dif-
ferent before the appearance of abundant metazoans and land
plants. Before land plants appeared, rivers were predominant-
ly braided (Schumm 1968; Cotter 1978) and eolian action was
enhanced (Dalrymple et al. 1985). These non-actualistic ef-
fects also played an important role in the continental margin
successions (MacNaughton et al. 1997).
The studied deposits were very probably deposited under a
strong influence of a fluvial environment (braided river?).
Relatively rare occurrence of silt fraction can be explained by
wind action. This action was strong without the protective ef-
fect of land plants, especially in episodically flooded areas.
The preferred removal of fine material would help in produc-
ing bedload-dominated rivers. The rapid transport, high con-
tent of transported material in bedload, arid to semiarid condi-
tions(?), non-cohesive unstable banks, probably high width:
depth ratios and steep channel gradient, led to rapid switching
of the channels. Braidplains were enormous (McCormick &
Grotzinger 1993) and shorelines were dominated by rapid
shifting of river mouths (MacNaughton et al. 1997). The dep-
osition in the studied case was affected by the marine action in
marginal or distal areas (interdistributary area, braid delta?)
mainly during reduced fluvial input or channel shifting. Shal-
low marine conditions close to the shoreline can be supposed.
Wind action could also add “exotic” fine-grained (silt-sized)
material, especially into a marine depositional environment
(Dalrymple et al. 1985). Multiple sources for sandstone with
grain-size bimodality are evident. Clay deficiency in the stud-
ied deposits can be connected with rock provenance or type of
Recurring alternation of terrestrial/fluvial and marine influ-
ences through the sediment succession can be supposed. Evo-
lution of sedimentary environments upward through the suc-
cession is in question. Various petrological criteria can reflect
the evolution of the source area or climatic differences
(Skoček 1980). These criteria are: 1. The upper unit is miner-
alogically more mature (quartzose sandstone), whereas the
lower unit has a higher content of less stable components
(feldspar, etc.). 2. The upper unit has strong dominance of
monocrystalline quartz grains and the proportion of quartz is
generally higher than in the lower one. The content of mono-
crystallic and aggregate quartz grains is very irregular in the
Fig. 8. Acritarchs from the Měnín-1 borehole. 1 – Leiosphaeridia sp.; depth 856.2 m, size 60
m. 2 – two specimens of Lophos-
phaeridium bacilliferum Vanguestaine, 1974, surface covered with extremely delicate outgrowths; depth 856.2 m, size 30
m. 3 – aff.
Tasmanites tenellus Volkova, 1968, wall finely perforated; depth 1565.0 m, size 65
m. 4, 6 – Lophosphaeridium bacilliferum
Vanguestaine, 1974; depth 856.2 m and 1565 m, size 34 and 27
m. 5, 7 – Lophosphaeridium sp. indet., aff. L. truncatum Volkova,
1968; depth 1565—1566.5 m, size 35 and 39
m. 8 – Archaeotrichion sp. indet.; depth 1565 m, size 44
m. 9 – Asteridium lanatum
(Volkova) Moczydłowska, 1991; depth 1565 m, size 27
m. 10 – Fragment of ?Tanarium sp., aff. Tanarium conoideum Kolosova,
1991; depth 1565—1566.5 m, size 70
m. 11 – Comasphaeridium velvetum Moczydłowska, 1988; depth 1565—1566.5 m, size 37
12 – Asteridium tornatum (Volkova) Moczydłowska, 1991; depth 1565.0—1566.5 m, size 23
m. 13 – Fragment of ?Tanarium sp., aff.
T. irregulare Moczydlowska et al., 1993; depth 1565.0—1566.5 m, size 105
CAMBRIAN SILICICLASTIC SEDIMENTS (CZECH REPUBLIC) 77
lower layer (Maštera 2000; Zádrapa & Skoček 1983). 3. The
content of stable minerals in the heavy mineral spectra gener-
ally increases to the top of the sedimentary succession. Espe-
cially the amounts of garnet and apatite distinctly increase at
the expense of zircon (Dvořák 1998). It can be supposed that
the hypothetical evolution of the source area also affected the
depositional area (Blair & McPherson 1994). The abundant
presence of subrounded quartz grains can be connected with
prolonged transport or multiple redeposition.
The unicellular microfossils presented here were extracted
from the sediments, which form the basal member of the clas-
tic cover of the Brunovistulicum (Dudek 1980) or Moravo-
Silesian terrane (Pharaoh 1999). The Brunovistulicum ex-
tends from northern Austria to southern Poland (Upper
Silesia). It is reworked into para-autochthonous nappes along
the eastern termination of Variscides on its western side and
concealed under the Carpathian and Alpine orogenic belts in
the east (Jelínek & Dudek 1999).
The present position of the Brunovistulicum south of the
Trans-European Suture Zone points to its Gondwanan, Pan-
African affinity (Nehyba et al. 2001). A collage of blocks
forming the Trans-European Fault Zone is generally regarded
as a suture of the former Tornquist Ocean, dividing the south-
ern margin of Baltica from peri-Gondwanan terranes. Gond-
wanan affinity is explicit for such microcontinents as Peruni-
ca, Iberoarmorica and Avalonia. The region of E Moravia and
SE Poland, including the Łysogóry and Małopolska blocks, is
distinguished by autonomous geological, paleontological and
petrological record (Franke 1995; Źelaźniewicz 1998). Previ-
ously, affinities of the Moravo-Silesian Zone to the East Euro-
pean Platform and to the Ukrainian block have been suggest-
ed (e.g. Suk et al. 1984; Havlíček et al. 1994).
In the provenance study of detrital zircons in Cambrian sed-
iments, Belka et al. (2000) proposed the Early Paleozoic (be-
fore mid-Cambrian) docking of the Małopolska Massif and
Upper Silesia to the Eastern European Platform. Moczyd-
łowska (1997, 1998, 1999) and other authors proposed the po-
sition of Upper Silesia within Eastern Avalonia, in a close
proximity to Iberia. The Avalonian composite terrane (McK-
errow & Cocks 1995; Nance & Murphy 1996), rifted from
Gondwana in the Early Cambrian, was finally accreted to the
Trans-European Suture Zone (the final docking to Laurussia).
Recently, the presence of detrital zircons of “Cadomian”
age in the Okuniew IG-1 borehole situated within the EEP
part of Poland, led Valverde-Vaquero et al. (2000) to dispute
the role of radiometric ages as a sole criterion for determina-
tion of terrane provenance.
The peri-Gondwanan belt of microcontinents (Avalonia,
Armorica, Iberia, Perunica, Hungary, Turkey, Karakorum,
Yangtze Platform) is distinguished in the Arenig/Llanvirn
time interval by “Mediterranean” fossil marine microplank-
ton, by clastic sedimentation with common oolitic iron ores
and an absence of carbonates. The geographical differentia-
tion of acritarch assemblages in the Early Ordovician (Vavr-
dová 1997b; Servais & Fatka 1997) is well documented. As-
semblages of plant microfossils described by Jachowicz (in
Buła & Jachowicz 1992 i.e. Baltisphaeridium—Ordovicidium—
Peteinosphaeridium assemblage) represent unequivocal evi-
dence of the low-latitude, warm-water latitudinal position of
Upper Silesia in the Early Ordovician.
The Early Cambrian fossil record of unicellular marine mi-
croplankton is not yet known in sufficient detail to allow a
definition of fossil phytoplankton bioprovinces comparable to
the well recognized Early Ordovician acritarch provincialism.
Moczydłowska (Moczydłowska & Vidal 1992; Moczydłowska
1991, 1998) maintains worldwide uniform distribution of Ear-
ly Cambrian acritarchs. However, the composition of Early
Cambrian assemblages of palynomorphs from the Měnín-1
borehole is closely similar to coeval microplankton popula-
tions known from Baltoscandia, from Eastern Europe (Latvia,
Estonia), and eastern Poland and Ukraine (Fatka &Vavrdová
1998; Vavrdová & Bek 2001). Some acritarch species com-
mon in southern Moravia such as Sagatum priscum (Kirja-
nov) Vavrdová et Bek, 2001 and Liepaina plana Jankauskas
et Volkova in Volkova et al., 1979 have not been recorded
outside Baltoscandia and the Eastern European Platform. The
Baltic affinity of Brunovistulicum is supported both by the
Early Cambrian macrofaunal fossil record (Early Cambrian
Baltic types of trilobites in Goczałkowice borehole, Upper
Silesia; Orłowski 1975, 1985), geological structure (Dvořák
1968) and sedimentological development, namely the pres-
ence of platform carbonates in the Arenig of Upper Silesia,
Małopolska and Łysogóry blocks (Belka et al. 2000; Valver-
de-Vaquero et al. 2000). The Brunovistulicum, like Baltica,
was apparently translated from the high southern latitudes in
the Early Cambrian to the low-latitude warm-water realm in
which the Early Ordovician carbonates originated (Fig. 9). On
the other hand, microplates of the peri-Gondwanan origin
drifted in opposite direction, from warm and temperate water
masses in Early Cambrian to the subpolar position in the
Arenig/Llanvirn (Cocks & McKerrow 1995; Cocks et al.
Fig. 9. Position and translation of peri-Gondwanan (dark arrow)
and Baltica-related (light-grey arrow) terranes at the Baltica/
Gondwana interface in the Early Cambrian. Position of Upper
Silesia as proposed by Moczydłowska (1997). T = Turkey, S. E. =
1997; Pharaoh 1999). Apparently, geological, petrological,
faunal and microfloral data put some doubts on the Trans-Eu-
ropean Fault Zone as a suture of the former Tornquist Ocean
(Cocks et al. 1997; Berthelsen 1998).
Stratigraphy. The newly recovered microfossils allow us to
determine the age of marine transgression in southern Mora-
via as the Early Cambrian (Platysolenites antiquissimus Fau-
nal Zone). The basal transgressive deposits represent the old-
est succession so far recognized in the eastern margin of the
Environment. Lithofacies and ichnofossils indicate the pres-
ence of shallow marine deposits in the units previously re-
garded as exclusively terrestrial.
Palaeogeography. New data further support the affinities of
the Moravo-Silesian Zone to the Baltica.
Acknowledgement: The study was kindly supported by the Re-
search Projects CEZ J07/98-1431000004 and CEZ: Z3 013 912.
We thank Jiří Adamovič (Prague) for critical reading of the
manuscript and improvement of the English presentation. The
Moravian Oil Mines Comp. kindly enabled us the access to
the core material. František Patočka (Praha) kindly contribut-
ed to completing the published sources. Constructive criti-
cisms and comments of the reviewers, Prof. Małgorzata
Moczydłowska, Prof. Albert Uchman and Dr. Jindřich Hladil
are gratefully acknowledged.
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