GEOLOGIJA 24/2, 327—330 (1981), Ljubljana
UDK 593.12 + 582.26:552.24:551.736 + 555.761(497.13)=20
Permian-Triassic boundary at Brušane village in Velebit Mt.
Anton Ramovš
Katedra za geologijo in paleontologijo, univerza Edvarda Kardelja
61000 Ljubljana, Aškerčeva 12
Vanda Kockansky-Devidé
Geološko-paleontološki zavod. Sveučilište u Zagrebu,
41000 Zagreb, Socijalističke revolucije 8/II
Abstract
Upper Permian boundary dolomite from Brušane in Velebit has
previously been considered te be devoid of fossils. Bedded and platy do-
lomite is mostly dark gray in colour. Micritic and sandy varieties can
be distinguished. Now fusulinids, microforaminifers and calcareous algae
have been determined from the uppermost dolomitic layer. Gymnocodium
and Glomospira are the most abundant fossils associated with Staff ella cf.
transiens.
Kratka vsebina
O zgornjepermskem mejnem dolomitu pri kraju Brušane na Velebitu
so včasih mislili, da je brez fosilov. Plastoviti in ploščasti dolomit je
v glavnem temno siv, mikritne in peščene strukture. V vzorcih vrhnje
dolomitne plasti so bile določene fuzulinide, mikroforaminifere in apne-
ne alge. Najbolj pogostna fosila sta alga Gymnocodium bellerophontis in
foraminifera Glomospira sp. div. Tu in tam ju spremlja Staffella cf. tran-
siens.
Well known Permian cross-section near village Brušane in Velebit Mt. fi-
nishes with gray, so called "boundary dolomite", which was previously consi-
dered to be without fossils (M. Salopek, 1942, 251). Nevertheless, micro-
fossils can be found, at least in the area investigated, a little north of Velnačka
Glavica hill (V. Kochansky-Devidé, 1965, 111). The authors have now
sampled a part of the cross-section beginning eight metres below the Permian-
Triassic boundary and finishing at the very contact. Fossils are not well pre-
served and not very abundant, but they can be found even in the top Permian
stratum. The following forms have been determined:
Fusulinidae : Staff ella cf. transiens Kochansky-Devidé, Staff ella sp.
(with nankinelloid juvenarium), and Schubertella? sp.
328	Anton Ramovš & Vanda Kochansky-Devidé
Tabla 1 — Plate 1
1 Glomospira sp. 3 samples; Globivalvulina sp., Permocalculus sp. No. 1/3. X 10
2 Hemigordius sp. 5/2. X 30
3—4 Staff ella sp., 5/1, 3,1. X 30
5 Ammodiscus sp. in the intraclast 1/1. X 30
6 Dasycladaceae gen. indet. gen. n. ? No. 9. X 30
7 Gyroporella ? sp. 9. X 30
8—9 Gymnocodium bellerophontis (Rothpietz). 5/1, 3/1. X 30
Photographs made by Pavlešić
330	Anton Ramovš & Vanda Kochansky-Devidé
Microforaminifers : Ammodiscus, Ammovertella, Calcidiscus, Glo-
mospira sp. div., Hemigordius sp. div., Palaeotextulariidae gen. ind. and Neotu-
heritina.
Calcareous algae: Gyroporella sp., bulbous dasyclad alga, n. gen. ?,
Gymnocodium bellerophontis (Rothpietz), and Permocalculus cf. fragilis (Pia).
Problematica : Bacinella sp. and Spherae.
In 17 slides the most abundant fossils are Gymnocodium and Glomospira.
Sporadically, Staffella cf. transiens is rather frequent. These three forms have
also been found in the uppermost Permian stratum. Mizzia velebitana Schubert
and Mizzia ydbei (Karpinski) which are abundant north of Velnačka Glavica
hill, do not occur in the uppermost eight metres of Permian dolomitic series.
The upper part of Permian dolomite is partly layered (thickness of layers
about 30 cm) and partly platy (thickness of plates 5—15 cm). Dolomite is mostly
dark gray and has in general densely micritic to finely sandy appearance.
Lower Triassic dolomite is more pale-coloured then Upper Permian carbonate
rocks, usually a little yellowish in colour, fine-grained, banded and contain
somewhat mica. Thin sections made of oodolomicrite and finely- and rarely-
porous dolomicrite do not contain fossil rests. About 30 metres above the lower-
most Triassic dolomite platy dolomite rich in mica occurs, also with no visible
fossil rests.
Gradual transition of the Uppermost Permian dolomite into Lower Triassic
dolomite can be followed in the whole Upper Palaeozoic belt Brušane-Baške
Ostari j e. Besides the locality described, it is especially evident on the road
Brušane-Baške Oštarije, just ahead of the Takalice pass.
Towards the south-east, in continuation of the Palaeozoic uplifted blocks
near Risovac, Mali Kraj an Citluk, Uppermost Permian dolomite is overlain
by yellowish sandy Lower Triassic dolomite. Farther to the south-east, in the
area of Počitelj, Medak and S v. Rok the geologic relationships are quite diffe-
rent. Permian boundary-dolomite can be missing and the sedimentation of
Triassic can start with typical Werfenian slate. At the south-eastern margin of
the Palaeozoic belt, near Ričice, Permian-Triassic boundary has mostly tectonic
character.
References
Kochansky-Devidé, V. 1965, Karbonske i permske fuzulinidne foramini-
fere Velebita i Like — srednji i gornji perm. Acta geologica 5, 101—150, Zagreb.
Salopek, M. 1942, O gornjem paleozoiku u okolini Brušana i Baskih Oštarija.
Rad Jugosl. akad. 274, Mat. prir. razr. 85, 218—272, 6 tab. in 2 geol. karti, Zagreb.