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GEOLOGY OF THE LEPOGLAVA AREA (NORTHWESTERN CROATIA)
Antun Šimunić
Sažetak
This paper presents a condensed review of the results of geologic
investigations carried out on Mt. Ivanščica in the last decade. Ba
sed on paleontologic and hthologic characteristics, the following
stratigraphic members have been separated: Upper Paleozoic, Lo
wer, Middle and Middle-to-Upper Triassic, Liassic, Jurassic Creata-
ceous, Neogene and Quaternary.
Upper Paleozoic deposits, which occur as small isolated outcrops
only on Mr. Ivanščica, are represented by slightly metamorphosed
clastic rocks, which are unconformably overlain by coarse-grained
clastic sediments. A gradual transition into typical Lower Triassic
clastic deposits has been established (so-called Seiser beds), which,
in turn, pass continuously upward into the so-called Campilian beds,
represented by thinbedded, dark grey limestones. Of all Mesozoic
rocks, Middle Triassic are the most widespread.
At Mt. Ivanščica, both Middle Triaslc stages are represented by
deposits. The Anisian consists of 'algal limestones and dolomites,
limestones with »filaments« and radiolarians, cherts, pelites, tuffs,
and spilites. The tuffs scattered between Lepograva and Margečan,
which had up to now been regarded as Tertiar, are also of the Mid
dle Triassic age.
In the Ladinian, carbonate rocks (limestone and dolomite) be
longs to the Middle-to-Upper Triassic. Predominant meimbers in
that complex are typical shallowater, algal, stromatclithic and on-
koidal dolomites, where the limestones of similar textural features
are less frequent. In several localities, a gradual transition of Upper
Triassic limestones imto the Liassic has been noticed.
Tithonina-Valanginian deposits overlie unsonformably (with an
ero'sional unconformity) Upper Triassic and Liassic sediments. There
occur thin-bedded, finegrained, partly silicified limestones, whereas
the occurrences of chert and calclithitarenites are less frequent.
In the Lower Cretaceous there are both calcareous and clastic
deposits with occurrences of ruffs and diabase. Aternations of gray-
wacke sadstones, calclithitsrenites, shales, cherts limestones with
radiolarians, and vitric tuffs are frequent, accompanied by spilitJz-
ed diabase. These are turbiditic and pelagic sediments, formed in
the so-called »eugeosynclinal« region.
In the time span between the Loiver Miocene to the Middle Sarma-
tian northwestern Croatia belonged to the southern marginal re
gion of the Paratethys. During this period larger or smaller areas,
depending on tectonic activity and bedrocks 'morphology, were co
vered by marine tranisgresions. In depresions formed at that time
were deposited beds of the Lower, Middle and a part of the Upper
Miocene.
After disintegration of the Parathertys and formation of the iso
lated fresh water Pannonian basin in the nortwestern Croatia terri
tory deposited sediments of the Lower and Upper Pannonian. After
the reestablishment of the connection between the Pannonian and
the Dacian basins were deposited brackish-fresh sediments of the
Lower Pliocene. Towards the end of the Pontian the Pannonian
basin disintegrrated into a number of fresh water lakes in which
fresh water clastic sediments were deposited.
In the region of Hrvatslko Zagorje tectonic movements were fre
quent and intensive from the Upper Paleozoic till the Quaternary.
In the fild only those movements which occured in the Neogene
and Quaternary are clearly expressed. In the region of Mt. Ivanšči-
ca the end of the Hercinian orogeny has been established, as well
as the all but complete Alpine orogenic cycle. The final uplifting
of Mt. Ivanščica and the formation of the present morphoiogy is
due to neotectonic movements, which took place in the Upper Plio
cene and Quaternary.
Ključne riječi
Hrčak ID:
133904
URI
Datum izdavanja:
5.12.1986.
Posjeta: 1.606 *