Organism communities and biofacies of the Fatra Formation (uppermost Triassic, Fatric) in the West Carpathians

Full text

GEOLOGICKÝ
ZBORNÍK — GEOLOGICA CARPATHICA 29, 1, BRATISLAVA,
JUNI
1978 113
JOZEF
MICHALlK  OTlLIA JENDREJÁKOVÁ*
ORGANISM
COMMUNITIES AND BIOFACIES OF THE FA-
TRA FORMATION
(UPPERMOST
TRIASSIC, FATRIC) IN THE
0 WEST CARPATHIANS
H
(Fig. 112)
Abstract: The aim of evolution of mutal relations of common fora
minifera, coral, brachiopod,
bivalve
and gastropod species of the upper-
most Triassic was to try to present the characteristics of ecology of orga-
nism communities and their classification in relation to the lithofacies
of sequences of that age in
West
Carpathians. Some species are also found
in
several biofacies, other are members of more firmly defined associa-
tions,
forming zonal strips, where — as others are found only locally, in
connection
with special conditions of the evironment. The created model
is the
first
attempt of this kind in Carpathian paleontological literature.
Key Words: Biocoenoses, biofacies, Uppermost Triassic,
West
Car-
pathians.
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Introduction
In
spite of the fact that in many formations (mainly in the Early Paeozoic)
of several regions of the world, biofacial and biocenotic analyses with attempts
for a reconstruction of relations and structures of biocoenoses are common, in
Mesozoic sequences of the
West
Carpathians similar studies have not been
carried out so far. The great amount of specimens of fauna in the Uppermost
Triassic and the about regularities of common occurence, gathered in the last
years, permit to make the
first
attempt of ranging of species into the probable
original associations and communities. The model surely contains many inaccu-
racies, owing to up to present only incomplete collecting of faunas from detailed
profiles in horizon after horizon, futher inaccuracies are caused by unequal
investigation of groups of organisms present (not investigated remain porifera,
worms, bryozoans, ostracodes, echinoderms and others). The study was based
on
information from 373 documentation points and profiles from the most
tectonic
units of the Central
West
Carpathians (with stress laid on the Kržna
unit).
Eighteen profiles were treated in detail: from each bed the macrofauna
was collected and sample taken for micropaleontological investigation. From
intercalations of marls and claystones samples were taken for palynological
investigation, which has not been finished yet. The obtained paleontological
*
RNDr.
J. M i c h a
1
 k CSc,
RNDr.
O. Jendrejáková CSc, Geological
Institute
of Slovak Academy of sciences, Dúbravská cesta, 886 25 Bratislava.

114 MICHALIK - JENDREJÁKOVÁ
material, which was the basis for paleobiocenotic study, on the whole consisted
of 49 polished sections of corals, assigned to 14 species, 6242 specimens of bra-
chiopods, belonging to 21 species, 13 genera, 3651 specimens of bivalves, belon-
ging to 136 species, 53 specimens of gastropods, ranged to 11 species and of
many other remnants of organism (worms, bryozoans, echinoderms, scapho-
pods etc.). The material for the analysis of representation of foraminifers was
provided by the study of 852 pieces of thin sections from the investigated
profiles of the Fatra formation. The studied material of brachiopods after their
treatment is gradualy deposited in the collections of the Slovak National Museum
in Bratislava, the material for the study of bivalves and gastropods is deposited
in the collections of the Dionýz Štúr Institute of Geology in Bratislava.
The investigation of fossil biocoenoses, besides fossils, was also based on ten-
tative makro- and microfacial analysis, analysis of textural and structural
features of sediments, the study of rhythmicism and dynamics of environment,
dependence of bio— and lithofacies, lithological and faunistic correlation of
profiles.
Environmental dependence by Foraminifera
Relations of foraminifers and their extension in dependence on the type
of lithofacies are studied in several formations and types of the sedimentation
environment in the history of Earth. In Triassic foraminifer faunas tracing of
these dependences was neglected for a long time. More often an apparent facial
connection with the surrounding sediment was stated but the acutal ecological
investigation started in the last five years only. Attention has been focused
especially on the study of foraminifers from Upper Triassic carbonate complexes
—
the Aflenz and Dachstein limestones (J. Hohenegger etW. Lobitzer,
1971;
J. Hohenegger et W. Pilier, 1975). The results obtained, based
on statistical methods, have shown quite a distinct dependence of the main
groups and some foraminifer groups on the environment. The ecology of invo-
lutines, investigation of environmental influence on the morphology of their
test was dealt with by L. Z a n i n e 11 i (1976 p. 67—77).
The West Carpathian Triassic foraminifers have been studied from the
viewpoint of their stratigraphic importance so far only. To questions of facial
depencence attention has been paid only incidentally in works aimed at litholo-
gical and microfacial investigation (K. B o r z a 1973, manuscript). The amount
of material gathered in the last years permits to carry out the first attempt
of characterization of foraminifer communities in relation to lithofacies of the
uppermost Triassic. Tracing of these dependences is based on faunal analyses
from 7 important profiles through the Fatra formation (237 thin sections, V3 of
them positive), from the northern and northwestern part of its area. The thin
sections containing characteristic foraminifer communities (12 pieces) were sub-
jected to microfacial analysis. (Carried out by Dr. K. B o r z a).
The sequence of the Fatra formation was distinguished and defined by J. M i-
c h a
1
í k (1974 a) (as a member of the „Kóssen-fmt."). The characteristic of facial
areas of this sequence as well as nearer data on the paleogeographical diferec-
tions and lithological description of the bed sequence of profiles are published
in the works by J. M i c h a
1
í k (1974a, 1975, 1977, 1977).

ORGANISM
COMMUNITIES
AND BIOFACIES 115
Fig. 1. Schematic map of Czechoslavakia with location of most important profiles
of the Fatra formation.
The
material for analyses of foraminifer assemblages comes from the follo-
wing
profiles (Fig. 1).
Profile No. 1. Hreška (Strážovské vrchy Mts., the locality is situated close to the inn
Hreška in
Valaská
Bela in the cut of main road Hava—Prievidza).
Profile No. 2. Dedošova
valley
(Velká Fatra, upper part of the eastern branch of the
Gaderská dolina
valley,
below the western slopes of mount Kržna). Type profile
of the FatraFormation.
Profile No. 3. Bystro (northern foothill of the
Velká
Fatra Mts., cutting of the state
road Žilina—Poprad in the
left
slope of the Váh river meander near the game
keeeper's cotage Bystro 50 m NW form the inflow of the
Bystrý
potok brook
into
the Váh).
Profile No. 4. Ráztoky (northern foothill of the
Velká
Fatra Mts., cut of the forest
road in the southern slope of the Lipová above the Ráztoky
valley
in the Nol
čovská dolina
valley
near Krpelany).
Profile No. 5. Belianska below Borisov (Velká Fatra Mts., central part, upper part
of the Belianska dolina
valley,
cut of the path from the Belianska dolina
valley
to
the cottage below the Borisov, about 200 m below the cottage).
Profile No. 6. Groove below the Zdiarska
Vidia
(Belianske Tatry Mts.).
Profile No. 7. NE above the cottage Kardolina near Tatranská kotlina (Belianske
Tatry) Mts.
The
sedimentary environment of the Fatra formation is characterized (J. M i
chalik, 1977) as a typical marine area with carbonate sedimentation prevai-
ling with manifestations of the influence of hot climate. The salinity of water
was normal to
slightly
raised. In the fauna are typical assemblages of
bivalves,

116 MICHALÍK - JENDREJÁKOVÁ
ostracodes, foraminifers, gastropods and algae, corals and brachiopods, totaly
lacking are cephalopods.
The foraminifers of the Fatra formation are very unequally represented in bed
sequences and in the individual profiles. The richest assemblages are found
in profiles No. 1 and 4 (Fig. 2). In general it may be stated that the spectrum
of foraminifer species of the Fatra formation is relativelly low. A typical mark
is the prevalence of species of the genera Glomospira and Glomospirella in rela-
tion to other foraminifer groups. Involutions often found associated with
glomospires and glomospirels, are characterized by small number of species and
individuals, small-medium-sized highly recrystalized tests. Their development in
the sedimentation environment of the areas under study was markedly kept
down. The species of sessile foramanifers dominate in basal and lower layers
of profiles 2, 4, 5. Representation of other associated forms (Agathamina, Nodo-
saria, Frondicularia, Ophtalmidium, Tetrataxis) is insignificant.
Tracing of dependences of the occurrence of the individual forms in more
complete profiles has shown that the majority of species are not strictly specia-
lized to a limited type of facies. They are passing—through—forms, found in
various facies of calm waters of the neritic sensu lato. It might be possible, ho-
wever, to distinguish types of foraminifer associations, recurring in the bed
sequence more or. less regularly in dependence on the type of lithof
acies.
1.
Communities of sessile foraminifers: Tolypammina gregaria, Tolypammina
sp.,
Planiinvoluta deflexa, Nubecularia sp., Calcitornella sp. In the Fatra forma-
tion they are bound to the sedimentary environments of organodetrital-crinoidal,
crinoidal and crinoidal-pseudoolitic limestones with fragments of gastropods
and bivalves. They are characteristic of basal, lower and midle layers of the Fatra
form profiles. The microfacial associations of sessile foraminifers are bound
to biosparites and intrabiosparites, being indicators for a shallow-water environ-
ment with stronger movement of marine water.
2.
Communities with a relatively higher share of involutines. They are not
very often. Present are exclusively forms with undifferentiated umbilical subs-
tance: Involutina tumida, Involutina communis, Involutina tenuis, Ivolutina cf.
impressa, Involutina sinuosa sinuosa. In general a tendency towards thinning
of the test wall and flattening may be observed in them. In the sense of L. Z a-
n i n e 11 i (1976, p. 69) these marks are a good indicator of diminishing energy
of marine water movement and are often in biomicrites pointing to a quiet
sedimentation in lagoonal environment. The associations of involutines of the
Fatra formation are usually associated with the species Glomospirella friedli,
Glomospirella tenuifistula. They occur in gastropod, megalodon, coral-brachio-
pod to lumachelle limestones, are communities of lagoonal-biostromatic envi-
ronment. Associations of this type were observed in the basal (profiles No. 1, 3),
lower (profile No. 2) and upper (profile No. 5) layers. According to microfacial
analyses the communities with relatively higher reach of involutines are most
often represented in biomicrosparites, intrapelsparites, intrabiosparites.
3.
Communities, in which of dominant position is Glomospirella friedli with
associated forms G. paralella. G. pokornyi, G. tenuifistula and rare involutines:
Involutina communis. I. tumida, are of the most widespread types of communi-
ties.
They a are predominantly bound to the oolitic and pseudoolitic facies.
They were found in basal (profile No. 7), middle (profile No. 4) and mainly
upper layers (profiles No. 1, 2, 3, 7) (Fig. 3).

ORGANISM
COMMUNITIES
AND BIOFACIES 117
.'
*S;L "v?"
k::
•
a«i:ÄiM;
4
Fig.
2. 1.
Profile
1 (119)
Hreška,
bed 23,
foraminifer intrabiosparite with
Glomospi
rella shengi. 2.
Profile 4(241) Ráztoky,
bed 33,
biointrasparite with
Glomospira cf.
sinensis.
3.
Profile 4(241) Ráztoky,
bed 32,
foraminifer biomicrosparite with
Glomospira
sp.
4.
Profile 7(348) Kardolina, foraminifer biopelsparite with
Glomospira
tenuifistula.
Magnification
60 x,
photo
F.
Martančk.

118 MICHALIK - JENDREJÄKOVÁ
4.
A remarkable type are associations formed by small tests of the species
Glomispirella shengi, G. facilis, Glomospirella sp., Glomospira cf. simplex, G.
sinensis, Glomospira sp. Their characteristics and extension are equivalent to
those of the communities of sessile foraminifers. Facially they are connected
with fine compact crinoidal, more rarely with crinoidal-pseudoolitic limestones.
As to microfacies, they are linked with biosparites and biomicrosparites. Their
environment is restricted to calm areas or areas with slightly active movement
of water. Largest extension they reach in the environment of deeper neritic.
In mass occurrence observed in profiles No. I and 4 (lower third of the upper
part).
5.
Foraminifers of the group Miliolina: Miliolina sp., Miliolipora sp., Ophthal-
midium sp. are of very little representation. A more noteworthy occurrence
may be observed in the middle part of profile No. 7 only. They are found in
dolomitized limestones, ostracode and bivalve limestones of the so called "Swa-
bian facies" in the coastal zone with disturbed salinity.
So far we cannot express our opinion to the facial relations of Triasina
hantkeni. In the sedimentation area of the formation only one case of
highly recrystallized tests of this species has been recorded (profile No. 5, upper
third of the middle part) occurring in massive crinoidal limestones (Fig. 4).
Tracing the dependences of the occurrence of the individual forms the view-
point of requirements to the environment three groups could be roughly disting-
hished:
1.
Forms of the lagoonal-biostromatic environment are most abudant in gast-
ropod—, megalodon—, porifera—, coral-brachiopod—, to shelly- limestones. They
are mainly represented by involutines: Involutina tumida, Involutina communis,
Involutina impressa, Involutina tenuis often associated with Glomospirella
friedli, Glomospira tenuijistula, Ophthalmidium sp., Tetrataxis inflata.
2.
Forms of extremely active shallow-water environment (or exposed neritic)
restricted to the environment of formation of pseudoolitic and oolitic limestones
are mainly represented by glomospirels: Glomospirella friedli, Glomospirella
pokornyi, Glomospirella paralella, more rarely associated with Glomospirella
shengi and glomospira tenuijistula.
Environment of deeper neritic, indicated by forms linked with organodetri-
tal-crinoidal and crinoidal limestones. Typical species are Glomospirella shengi.
Glomospirella cf. vulgaris, Glomospira sp. Less frequent are Glomospira gordia-
lis,
Glomospira cf. simplex, Glomospirella expansa, Glomospirella cf. densa,
Calcitornella sp., Planiinvoluta sp.
Environmental dependence by Anthozoa
To corals of the Fatra formation of the West Carpathians minimum atten-
tion has been paid so far only. In the last fifty years only several works were
published (V. Z á z v o r k a, F. P r a n
11,
1936. V. Náprstek, 1957, E. R o-
n i e w i c z, 1974), which by far could not exhaust the problem of this important
component of the communities of the uppermost Triassic. It may be stated, on
the contrary, that the coral faunas of that time remain little known and only
preliminary determinations give us an idea of them. Tracing of the dependences
of the occurrence of the individual forms has made possible to distinguish four
groups of this-fauna:

ORGANISM
COMMUNITIES
AND BIOFACIES
119
Fig.
3. 1.
Profile 4(241) Ráztoky,
bed 9,
biopelsparite with
Glomospirella
friedli,
60 x
magnif.
2.
Profile 7(348) Kardolina,
bed 1,
biomicrosparite with
Glomospirela
friedli,
magnif.
55 x. 3.
Profile 7(348) Kardolina,
bed 35,
sandy intrasparite,
Glomospirella
friedli,
magnif.
60 x. 4.
Profile 6(301) Groove below
the Mt.
Zdiarska Vidla,
bed 11,
biosparite with
Glomospirella
pokornyi, magnif.
58 x.
Photo
F.
Martančk.

120
MICHALÍK
 JENDREJÁKOVÁ
Fig.
4. 1. Profile 5(261) Belianska valley below Mt. Borisov, bed 22, biopelsparite
Triasina hantkeni, Involutina cf. communis,
Glomospirella
sp. magnif. 35 x. 2. Ftoiile
2(258) Dedošova
valley,
bed 8, biointramicrosparite with Involutina cf. communis,
magnif. 20 x. 3. Profile 4(241) Ráztoky, bed 23, biosparite with Planinvoluta carinata,
magnif. 35 x. 4. Profile 2(258) Dedošova
valley,
bed 3, biointrasparite with? Toly
pammina sp., magnif. 17 x.
Photo
F. Martančk.

ORGANISM COMMUNITIES AND BIOFACIES 121
1.
Form of lagoons and "lagoonal reefs" include species form marly and
gastropod limestones, occurring scattered. Here belong the forms Pinacophyllum
lejovae, Pinacophyllum sp., Pamiroseris rectilamellosa (Fig. 5c).
2.
Forms of the inner side of biostroms are usually found associated with
porifers, gastropods, calcareous algae (solenopores), brachiopods, megalodonts
and other bivalves. Usually they do not form own larger bodies, are rather
unintegrated component of many-species biostromatic growths. From known
forms are: Phacelostylophyllum robustum, Phacelostylophyllum medium and
Stylophyllum gracille (Fig. 5d).
3.
Forms of biostroms proper (of the central part) form, independent, massive
bunches, plates, blocks to banks — thus the core proper of often extensive zones
of biostroms. Only rarely associated with other organisms. Most abundant forms
are:
Parathecosmilia sellae, Rhaetiastraea tatrica and Astraeomorpha crassisepta
(Fig. 6a, b).
4.
Forms of the outher side of biostroms are often associated with the assem-
blage of Rhaetina gregaria: withering coral bunches were regularly densely
inhabited by juvenile individuals of this brachiopod. Concerned are mainly the
species Retiophyllia paraclathrata and Retiophyllia clathrata (Fig. 6c).
From the stratigraphic viewpoint, in corals, similary as in foraminifers, may
be distinguished diachronous forms (Retiophyllia clathrata, Retiophy-
llia paraclathrata). forms of the "lower part" of profiles (Pina-
cophyllum sp., Phacelostylophyllum medium, Stylophyllum gracile) and forms
of the "upper part" of pro fi les (Pamiroseris rectilamellosa, Astra-
eomorpha crassisepta). It seems, however, that the majority of coral species were
much more dependent on the environment and appear in the bed sequence
wherever a facies occurs, to which they were adapted. For clearing up of this
question it is necessary to study more representation of this group and paleobio-
logy of its representatives. The scale of species in the individual biocenoses
would be surely extended distinctly after such a study.
Environmetal dependence by Brachiopoda
The question of Triassic brachiopod ecology have been very little studied in
all-world scale. There is not work dealing with them systematically, in the best
case only short chapters or mentions are devoted to them in works directed
taxonomically, paleobiologically or paleobiogeographically (A. S. D a g y s, 1963,
1974;
C. K
1
o r e n, 1974; J. M i c h a
1
í k, 1975, 1976 a, b and others). The ques-
tions of ecology and paleobiogeography of brachiopod faunas form a very
extensive and complicated sphere of problems, solution of which is connected
with solution of stratigraphy, sedimentology, climatology, paleogeography,
paleobiocenotics and paleotectonics of sedimentary basins of that time. The
most important brachiopod species of the Fatra Formation is Rhaetina gregaria,
present in all brachiopod communities. In the sedimentation environment of the
Fatra Formation it may be thus considered as a diachronous species. When tra-
cing organisms associated with it, however, we may state that it occurs as a from
of at least three environments:
1.
Outer border of biostromes is characterized by constant link of the species
Rh.
gregaria to branched corals (Fig. 6c). The shells of Rh. gregaria are usually
small, rarely dwarfed individuals of the species Rh. pyriformis are found.

122 MICHALlK - JENDREJÁKOVÁ
2.
Small depressions and interspaces in the biostrome
proper are characterized by dense populations of Rhaetina gregaria.
3.
Biostromatic lagoons gave space for the populations of Rh. grega-
ria. with relatively large shells, asociated with the species Rh. pyriformis, Zug-
mayerella uncinata, Lepismatina austriaca, Discina suessi, more rarely also Zeille-
ria norica and Austrirhynchia cornigera) in areas near to the Orava depresion
(see J. M i c h a
1
í k, 1973, 1974, 1977) (Fig. 7).
The brachiopod communities were preliminarily distinguished also in the
Hybe beds, where they are much more varied and plentiful. From the view-
point of requirements /to the environment three groups of forms have been
distinguished:
1.
Forms of hard bottom may be found either independently or in other
facies,
where they inhabit microenvironments suiting the requirement of hard bottom
(shells of other animals, fragments in detritus etc.). Here may be ranged the species
Bactrynium bicarinatum, Discina suessi, Thecospira haidingeri (accompanied by the
species Atreta intusstriata a. o.). A solid bottom needed probably also the rhyncho-
nellid Euxinella subrimosa.
2.
Forms of "grey calcareous marls" occur together with the group of
bryozoan species (Berenicea hybensis, Stomatopora sp.), worms (Serpula aff. colubrina?,
Pomatoceras sp.), bivalves, gastropods and echinoderms. They include Fissirhynchia
fissicostata, Sinucosta emmrichi, Zeilleria elliptica, Z. austriaca, Z. norica, Zugmaye-
rella koessenensis, Rhaetina hybensis and dominating Rhaetina pyriformis.
3.
Forms of "dark-coloured marls" are only two (Zeilleria norica and
Oxycolpella oxycolpos). They occur, however, separatelly, often with Pholadomya sp.
Their relations will have be cleared up in future.
Eurybiotic forms of the Hybe beds are thus Rhaetina pyriformis and mainly
Zeilleria norica, which are not closely specialized to a limited type of facies.
Environmental dependence by bivalve molluscs
In spite that bivalves form a relatively well investigated component of
faunas of the Uppermost Triassic of the West Carpathians, their facial depen-
dences are very unclear, just as their detailed stratigraphic range. Therefore
also only a rough, provisional survey may be given about their biogeographic
relations and dependences. With the composition of Uppermost Triassic bi-
valve faunas was dealing M. Kochanova (1967), who determined also the
material of bivalves used in this work.
A. Diachronous forms include important "Rhaetic" fossils Atreta intusstriata,
Rhaetavicula contorta, Propeamussium (Parvamussium) schafhaeutli and the
practically "omnipresent" Placunopsis alpina.
_ >.
Fig. 5. Polished sections of some coral colonies of the Fatra formation, West Car-
pathians. Scale — 1 cm, photo H. Jendeková. a — Retiphyllia cf. paraclathrata Ron.
Suchá valley near Kláštor pod Znievom (group of Velká Lúka, Malá Fatra Mts.),
locality 072, b
—
? Retiophyllia sp. Gonove Lazy near village Hubina (Považský Inovec
Mts.),
locality 139, c — Pinacophyllum cf. lejovae Ron. — valley above the village
Diviaky nad Nitrou (group of Rokoš, Strážovské vrchy Mts.), locality 058, d — Phace-
lostylophyllum robustum Ron. Sokol valley near Zázrivá (Malá Fatra Mts.), locality 101.

ORGANISM COMMUNITIES AND BIOFACIES 123

124
MICHALlK

JENDREJÁKOVÁ
B.
Facially
more
forms may be
futher
divided
into
the groups:
1.
Forms
of the
littoral
environment
with disturbed salinity are
mainly
Gervillia
inflata, Myophoria emmrichi, Myophoria inflata, to
them
may be
(with
doubts) assigned the species Chlamys acuteaurita.
2.
Forms
of
biostromal
lagoons are a very
heterogeneous
group,
mainly
consis-
ting
of the species Cardita austriaca, C. cloacina, C. multiradiata, Chlamys win-
kleri,
Gervillia
praecursor,
Gryphaea pictetiana, Isocyprina ewaldi, I. germari,
Nuculana
deffneri, Modiolus hybbensis, M. minuta, M. schafhaeutli, Mytilus
psilonoti, Placunopsis mortilleti, Plicatula archiaci, Trapezium suevicum (Fig. 8).
3.
Forms
of the
inner
border
of biostromes are
bound
to the
environment
of
biostromal
platforms:
Corbula
alpina, Lopha haidingeriana, Rhaetomegalondon
incisus, Rhaetomegalodon sp., Conchodon infraliassicus.
4.
Forms
of the
margin
of
biostromal
platforms can be
found
(possibly
secon-
darily?)
also in the
innermost
zones:
Chlamys favrii, Ch.
trigeri,
Eopecten zejsz
neri, Liostrea
gracilis,
L. koessenensis, Parallelodon hettangiensis, Protocardia
rhaetica (Fig. 8).
5.
Forms
of the
deeper
neritic
are
represented
by
pectenid
bivalves Chlamys
bavarica, CM.
falgeri,
Chi. mayeri, Chi. valoniensis.
For
comparison
the
arrangement
observed in the
Hybe
beds may be
mentioned,
where
the
diachronous
forms comprise the same species.
Forms
more
dependent
on
facies
may be dividied
into
the following groups:
1.
Forms
of gray
marls,
futher
divided
into
the group of oysters (Cassianella
inaequiradiata.
Lopha hadingeriana), of "large" bivalves (Mysidioptera acuta,
M.
globosa,
M. incurvistriata, M. latifissa, Ctenostreon alpissordidae) and bivalves
with
byssus (Modiolus hybbensis, M. schafhaeutli,
Gervillia
inflata, Mytilus
preacutus).
2.
Forms
of
darkcoloured
marls are
represented
by the
infaunal
Pholadomya sp.
3.
Forms
of
channel
depressions comprise the group of "small bivalves"
(Avicula
salomoni, Mantellum subdupla, Myophoria stenonis, Pleuromya suevica) and
the
group of
pectenides
(Chlamys winkleri, Ch. simkovicsi, Eopecten zejszne
ri).
From
the stratigraphic viewpoint several groups may be distinguished,
found
in
various profile levels of the
Fatra
formation.
A. Stratigraphically
diachronous
forms
include
Cardita cloacina, Propeamus
ssium (Parvamussium) schafhaeutli, Rhaetavicula contorta (with the
maximum
occurence
in the
upper
part
of profiles) Placunopsis alpina, Atreta intusstriata.
Lopha
haidingeriana.
B.
Forms
with closer
limited
occurrence
include:
1.
Forms
of the basal
part
of profiles: Chlamys favrii tatrica, Ch. winkleri,
Modius
minutus, M. hybbensis, Myophoria sp., Plagiostoma
praecursor,
Neoschi
>
Fig.
6.
Polished
sections showing some biofacies of the
Fatra
formation.
Scale = 1 cm,
photo
H. Jendeková. a —
coral
limestone
with? Parathecosmilia cf. sellae. Panský
vŕšok
hill
near
Cičmany
(Malá
Magura
Mts.),
locality 029, b —
coral
limestone
with
Rhaetiastrea tatrica Ron. and Pinacophyllum sp.
settlement
Zelenáči
near
Va-
laská
Bela (Strážovské vrchy
Mts.),
locality 021, c — Colony of Retiophyllia clathrata
Emmr,
inhabited
by
population
of Rhaetina
gregaria
Suess. (a cavity
subcommuni-
ty).
Istebnianska
dolina
valley
(Malá
Fatra
Mts.),
locality 108, d — shelly gastropod
limestone,
covered with a layer of
compact
limestone
— Panský vŕšok hill
near
Cič-
many
(Malá
Magura
Mts.),
locality 029.

ORGANISM COMMUNITIES AND BIOFACIES 125

126 MICHALÍK - JENDREJAKOVÁ
zodus sp., Trigonodus sp. (found also below the base in the sequence of the
Carpathian Keuper), Isocyprina sp.
2.
Forms of the middle part of profiles: Conchodon infraliassicus, C. goeteli,
Rhaetomegalodon incissus, Rh. tatricus, Lima pectinoides, Nuculana percaudata,
Corbula sp., Gervillia praecursor, Modiolus sp. (schafhaeutli?) Pteria sp., Cardita
austriaca.
3.
Forms of the uppermost part of profiles: Cardinia sp., Chlamys valoniensis,
Chlamys dispar.
Environmental dependence by gastropods
Gastropods are a group very neglected in Triassic paleontological literature.
Even the authors dealing with gastropods, study them only incidentally. The
gastropods are not the main subject of their interest. Knowledge of the gastro-
pod faunas of the Uppermost Triassic fully corresponds to this state. Therefore
only roughly the presence of several morphologically more distinct types of
gastropods may be stated in the biofacies of the Fatra formation and Hybe
beds.
Generally it may be stated that the prevailing majority of gastropods of the
Fatra formation is linked with the biofacies of biostromal platforms and lagoons,
where were the best conditions for development of algal flora and the largest
amount of organic detritus. Connected with the fauna of sponges, corals and
brachiopods are the occurrences of forms Melánia sp., "Turritella" sp. (Fig. 6d).
(The gastropods of the Hybe beds: Straparollus szajnochae and Pseudomelania
quenstedti also come from the community of brachiopods and bivalves). Small
gastropods as Stuorella sp. are rather found in organodetrital lagoonal fades,
often together with the scaphopod ? Dentalium sp. (Fig. 7).
The number of gastropod forms in the biofacies of the Fatra formation is most
probably, as a matter of fact, much larger and after systematic investigation it
may be possible to establish more precise criterii of biofacial competence of
these animals.
Biocoenoses
A. Communities of the nearshore zone
1.
Communities of ostraoods and foraminifers. They are found predominant-
ly in dolomitic and dolomitized rocks, which fact might indicate an extreme
salinity of the environment. The community of ostraoods has not been studied
more in detail, from foraminifers are present types of the environment with
fluctuated salinity (see Chapter II).
2.
Communities of deposit- and sediment- eaters. Known only form the pre-
served burrows and traces after activity, conspicuous mainly in marly lamina-
ted limestones. The burrowing traces are also abundant in marly organodetrital
and dolomitic rocks. The competence of the representatives of this group has
not been studies more in detail.
Fig. 7. Schematic representation of relations of individual species of coral brachiopods,
gastropods and scaphopods to the environment and lithofacies of the Fatra formation
(Original).

ORGANISM COMMUNITIES AND
BIOFACIES
127
ENVIROMENTAL
RELATIONS
OF
CORALS,
BRACHIO-
PODS,
GASTROPODS
AND
SCAPHOPODS
OF THE
FATRA-
-MEMBER
Pinacophyllum
lejovae
Pamiroseris rectilam.
Phacelostylophyllum m.
Phacelostyloph. robust.
Stylophyllum gracile
Parathecosmilia sellae
Rhaetiastraea tatrica
Astraeomorpha crassis.
Ret iophyllio clathrata
Retioph.
paraclathrata
Rhaetina
gregaria
Rhaetina
pyriformis
ZugmayereUa uncinata
Lepismatina ausiriaca
Discina suessi
ľeilleria noricc
Austrirhynchic
cornig.
Melánia sp.
Jurritella'
sp.
Stuorella sp.
,DentaUum sp.
I
/ /s
brachiopod
shelly 1st. en in
i O
O cr
\
\

128 MICH ALlK - JENDRE JAKOVÁ
3.
Community of Gervillia + Myophoria. It represents one of the typical
communities of the so called "Swabian fades" (Fig. 8, 9). Its members are the
characteristic bivalves Gervillia inflata, Myophoria inflata and M. emmrichi,
occurring sometimes with valves of Chlamys acuteaurita. The community was
probably living on intertidal of the coast.
B.
Communities of biostronal lagoons
1.
Community Rhaetavicula+Placunopsis+Atreta. It represents an immature
community as the forms mentioned are a component of many communities of
biostronal langoons. With further stabilization of the faunistic ecosystem some
of the following communities might have developed from it (Fig. 9).
2.
Community Cardita + Nuculana + gastropods (Fig. 9) includes the .naj or
part of bivalve forms of biostromal lagoons. It is found in grey marly shelly
limestone. It contains burrowing types of byssate bivalves, which probably lived
on shallow-water flast with algal covers. Known from thanatocoenoses only.
3.
Community Propeamussium + Gryphaea pictetiana + Gervillia (Fig. 11).
Occurring in bluishgrey crinoidal and oolitic limestone. It contains species re-
quiring a more solide substratum in shallow-water environment (Propeamussium
(Parvamussium) schafhaeutli, G. pictetiana, Gervillia praecursor, Chlamys win-
klari.) Often preserved in thanatocoenoses only.
4.
Community Placunopsis + Isocyprina is found in dark-grey lumachelle li-
mestones, which in the environment of formation are very similar to community
No.
2. Known from thanatocoenoses.
5.
Community Rhaetina + Zugmayerella + Modiolus was living in shallow-
water parts of lagoons (marly limestones and marls with intercalations of
dolomites). Its typical representatives are, beside the brachiopod species Rhaeti-
na gregaria and Rh. pyrijormis, Zugmayerella uncinata, also the less frequent
Lepismatina austriaca, Discina suessi and Zeilleria norica. In areas near to the
channel-like "Orava depression" (J. Michalik, 1974) is also found the bra-
chiopod Austrirhynchia cornigera. Beside brachiopods the bivalves Modiolus mi-
nutus, M. hybbensis, M. schafhäutli (thus byssate forms), Lopha haidingeriana and
others are bound to the community. Preserved are parts of original biocoenoses.
C. Communities of the inner biostrome zone
1.
Community of megalodonts + Lopha + Corbula. The community of mega-
lodontid bivalves was investigated most thorougly by A. G a ž d z i c k i
(1971,
1974) from the northern slopes of the High Tatra. The megalodonts formed
cluster-like groups of shells, oriented with their umbos downward, partly diving
into the sediment. The bottom was relatively solid, coherent, formed by calca-
reous,
rapidly solidifying mud (Fig. 10). The biocoenoses are partly preserved.
>
Fig. 8. Schematic representation of relations of the individual species of bivalves
to the environment of the Fatra formation. Scale of lithofacies as for. Fig. 5. Original,
according to data of M. Kochanova.

ORGANISM COMMUNITIES AND BIOFACIES 129
ENVIRONMENTAL
RELATIONS OF
B IVA LVI A OF THE
FATRA - MEMBER
Atreta intusstriata
Rhaetavicuia contorta
Propeamussium / P/ sc'n.
Ptacunopsis alpina
Ger v
i U
ia inflata
Myophoria emmrichi
Myoph.
inflata
Chlamys acuteaurita
Cardita austriaca
Card,
cloacina
Cara.
mult iradiata
Chlarnys winkleri
Gervillia praecursor
Gryphaea pictetiana
socyprina ewalrji
Isocyprina germari
Nuculana deffneri
Modiolus hybbensis
Modiolus minutus
Modiolus scnafhaeutli
Mytilus psilonoti
Piacunopsis morti lleti
Plicatula archiaci
Trapezium suevicum
Corbula alpina
I opha haidingeriana
Rhaetomegalodon incis.
Conchodon mfraliass.
Chlamys favri
Chlamys trigeri
Eopecten zejszner
Liostrea gracilis
Liost. koessenensis
Parallelodon hettang.
Protocardia rhaetica
Chlamys bavarica
Chlamys talgeri
Chlamys may e ri
Chlcmys valonienSis
slope ~ biostrome ~~ lagoon ~~ shore
outer • central • inner

130
MICHALlK

JENDREJAKOVÁ
2. Communities
of
gastropods and algae. The fauna
is
mostly formed
by
small
(herbivorous?) gastropods, found
in
fragmentary shelly
to
organodetrital
ol
°
Th T6?"63
"
"f Ylkl dUSterS
are
f°Und
S™U sh<^ o
seb-
rat'
componentprobably green algaehave
not
preserved
in
fossil
3.
Community
of
corals
+
sponges
+
gastropods (Fig.
10)
forms already
the
transltlon
to
actual biostromal growths.
It
contains abundant forms
of
calca
ITmSiZVll^T^^0
far)'
C°ralS
Pha^stylophyllum
robustum,
Ph. medium, Stylophyllum
gracile
a.
o., populations
of
the brachiopod Rhaetiná
gregana
large gastropods
(Pseudomelia
sp., Melánia Sp.
a. o.) and
biSves
(Loptia haidingeriana).
D.
Communities
of
the central biostrome zone
Frn^^r^^
COrals
They
have
n°t
been investigated more
in
detail.
ST,
ti
S/ffmmeä
are
PreSent here
Parathecosmilia
sellae,
Rhaetm
straeatatnca
and
Astraeomorpha
crassisepta.
The number
of
the present species
zonnfT
^? K6fardÍng \° the
faCt that
the
immunities were
living
in
the
HSP!
<fT
™ence'
a
larse Part
of
coral skeletons
was
destroyed imme-
diately after death (sometimes also before)
of
coral polyps
,^1?^™^
oi
t
R!laetina
gregaria
was
living
in
channellike depressions and
small interspaces
of
the zone
of
biostromes. The brachiopods inhabited
in
dense
populations
the
bottom
of
small depressions
(J.
Michali
k 1975 Fig 221
where they were protected
wave
action. The bottom
was
formed
by
calcareous
organic detritus, possibly solidified
by
algal covers (?) (Fig. 10).
E. Communites
of
the inner zone
of
biostromes
J^T1?7
Rhaetina
+
COmls
(Fig" 10)
represents
a
population
of the
ivil
R^etmaýregana
(rarely with dwarfed individuals
of Rh.
pyriformis),
Íhhrv
6
Tlr0nment
of
hiSh
turbulence
at
the margin
of
coral biostromes
The
brachiopods were mostly attached
by
pedicle
to
dead corallites
in
interspa-
ces
of
coral bunches sometimes their shells have preserved
in
original orienta-
tion
up to
present
(J.
Michalik, 1975; Fig. 22). Comparison wfth the recent
Zmcomuni
TrhTna
(J R A
N°ble
6t aL'
1976) indicates
^SBO
XaXgegariatD2)a
^
SUbc"^
°f *» °^al
—unity
F.
Communities (?)
of
the biostromatic complex margin.
1. Association
of
Protocardia
+
Chlamys
favrii
found
in
darkcoloured orga
nodetrital
to
fragmentary shelly limestone:
it
typical species
is
Protocardia
rhaetica
found together with
valves
of the
pectenid
Ch.
favrii
(the possibility
cannot
be
excluded that there
is a
postmortal association only) (Fig
11)
Fig.
9.
Scheme
of
communities
of
nearshore and biostromaticlagoonal facies
of
the
Fatra
formnfinn
nrifrinoi
Fatra
formation. Original.

ORGANISM COMMUNITIES AND BIOFACIES 131

132
MICHALÍK
 JENDREJÁKOVÁ
(Fig. 11).
G.
Communities of the open neritic
Summary
1. The investigation of
fossil
organism remains nf thA
FQ+V.
f
the
Sr/o ,
lme(lab0Ut
fadal and bi0Cen0tic nations of organisms of
ZS^AT"0*and only eight may be Lsidered s^s s
3
Based
on the study of
bivalve
nekrocoenoses (K. M. ' S u 11 a n o v e t al
1975),
however,
xt may be supposed that, at the absence of more distinct current
transport, the conspicuousness of representation of
valves
of te
specks
n
necrocoenosxs can be a reflection of its importance in the mother bocoTnos"
ZTi^ZT™^:?Xrn
by secondary factors (resisteni: =
^.Reconstructed was the rough composition of thirteen biocoenoses•
seven
of
wallS:•
pS aCqmre
m°re
imP0rtanCe' Ín
Places
with finer bottom
na
6: The majority of communities from the Fatra formation are apparently alio
patric This fact is comprehensible regarding to the circumstanceThat tI
underher of this sequence are abiogenic deposit of the C^S^L^r and
Fig. 10. Scheme of communities of the biostromatic complex of the Fatra formation
Original.

ORGANISM COMMUNITIES AND BIOFACIES 133
;
.'•I..
:.:. ;•• ř.
i:
ÍSI
J
•'
p:.\i
;.f§
: |:|
;:|Í::
p|P|r
#11
:f-
;
'
.. .:.. • ,.:

134 MICHALlK - JENDREJÁKOVÁ

ORGANISM COMMUNITIES AND BIOFACIES
\^z

136 MICHALÍK  JENDREJÁKOVÁ
in
the environment proper of the Fatra formation sedimentation basin
living
cen
ditions
were
very
variable and consequently there was not enough time for
development of sufficiently stable, welldeveloped domestic communities with
strictly limited ecological functions of their members.
The
development of communities was
always
interrupted by catastrophic
events, caused by seafloor oscillations: old communities were destroyed and
the
space was inhabited again by populations of eurytopical species. While the
conditions
set in were lasting, these populations gradually changed into specific
communities:
usually they were, however, destroyed sooner (by drying up. higher
salinity, washout or change of depth)
than
they could have specified.
7. In sequences of the Hronic and Gemeric indications of phyletic relations
maybe noticed in organic assemblages, as also a larger diversity and stability
(localities Hybe, Goštanová
etc.).
This fact
fully
agrees with the model of
H.
B. Rollins — J. Donahue (1975), in which the increase of these pro-
perties of communities in partly separated basins, towards the
seaway
is suppo-
sed (p. 261).
Translated by J. PEVNÝ
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Review
by J. BYSTRICKÝ Manuscript received June 15, 1976