Dark sediments from the Sztolnia creek (Pieniny
Klippen Belt, Poland)
Patrycja Wojcik – Tabol
Institute of Geological Sciences, Jagiellonian University, Oleandry 2a, 30-063 Krakow
Geology
The Pieniny Klippen Belt (PKB) is situated between the Inner and the Outer Carpathians.
Occurring there facial distinction of the sediments is typical for various deposition realms. It
has been a base to distinguish a few successions, i.e.: the Pieniny or the Czorsztyn
successions. In late Mesosoic time, the Pieniny Basin was a few hundreds kilometres in
width and deposition took place in the different environments, from shallow shelf to deep
bathyal zone (Birkenmajer, Gasinski, 1992). Investigated sections are situated in Eastern part
of the Polish part of the PKB.
Samples
The samples are collected from sections located in the Sztolnia creek. Generally, dark
“flysch – type” sediments, called the Szlachtowa Formation (Magura Succession), were
selected as significant for investigations. Furthermore, the mudy sediments with
intercalations of black shales (Kapusnica Fm., Branisko Succession), occurring in the upper
course of the Sztolnia creek were also collected (Birkenmajer, Myczynski, 1977).
Results
The complex of the dark, clastic rocks has consisted of mudstones with sandy
intercalations.
Sandy layers consist of calcite, quartz and feldspar. No order has been noted. Grains are
angular and crushed. Quartz shows brown and purple cathodoluminescence that indicates its
igneous and metamorphic origin. Blue and green luminescence is typical for feldspar, caused
by Ti2+ and Mn 2+ (Marshal, 1988).
Mudstones are mostly composed of clay minerals. They appear as slight sheets lying
parallel. Among them, muscovite/illite and chlorite have been distinguished. Common
organic matter, associated with iron sulphide has been recognized there. Pyrite appears as
spherical forms (<100 m. diam.) and irregular concretions (2 mm diam.). The first one
have been interpreted as pyritized plankton microfauna, i.e.: foraminiferids and Radiolaria.
The samples from the upper course of the Sztolnia creek are different. Above the waterfall,
the complex of disintegrating, red and grey shales has been investigated. Lamination,
fractionation and irregular bioturbation have been observed. The samples are built of clay
minerals (illite and sericite), quartz, dolomite, feldspar, without calcite. Quartz, dolomite and
feldspar occur as relatively large grains. Red luminescence of dolomite and feldspar is
activated by Fe3+. In contrary to diagenetical quartz, witch is dull.
Angular fragments of carbon rich substances are dispersed in rock material.
Size of grains has increased gradually, therefore term fractionation is correct. Within layers
of mudstones, irregular bioturbations have been observed.
Rare
microfauna
is
represented
by pyritized
Radiolaria
and
agglutinated
and
benthicforaminiferids.
Red part of shely complex includes slight, black intercalations. Along their lower
borderline, green “shadow” has been noted. Upper boundary is acute – red material goes
down in underlying black mud. Red layer contains of wispy – shape organic matter.
Maximum concentration of C
org
has been recognized in black shales. In contrary to grey
shales, reds contain of less dolomite and feldspar, but they are enriched in 7Å - clay mineral,
probably Fe-Mg chlorite (chamosite). Increasing share of Mn2+ has been also determined
there.
Below the waterfall, black shales have occurred. Significant concentration of organic
matter and iron sulphides causes their dark colour. Amorphous organic matter is dispersed or
occurs as lens – shape assemblage. Benthic foraminiferids and Radiolaria have been noted.
They are mostly pyritized or calcificated.
Conclusions
First group of investigated samples is typical for shallow water, high – energy
sedimentation regime. Shely layers looks like tempestite. The organic matter has preserved
thank to rapid covering by sandy material.
Second type of described material represents turbiditic sediments. These were
deposited on the lower continental slope, above CCD level. Bottom water might be oxic.
Change of colour (red/green) reflects fluctuation of redox potential, consequent of assembly
of organic matter. Organic substance has been delivered periodically. Pyritization of
plankton microfauna took place probably in water column.
The samples collected below the waterfall are difficult to interpretation because of
strong calcification. It is possible, that they represent pelagic sediment, deposited through
slow fall from water column.
In all samples, diagenetical processes (early and late) have been acted. They are
marked as concentration of framboidal pyrite, corroded surfaces of grains and presence of
chlorite and sericite.
References
BIRKENMAJER
K.
and
GASINSKI
M.
A.
1992.
Albian
and
Cenomanian
palaeobathymetry in the Pieniny Klippen Belt. Cretaceous Research, 13, 479-485.
BIRKENMAJER K. and MYCZYNSKI R. 1977. Midlle Jurasic deposits and fauna of the
Magura Succession near Szlachtowa-Pieniny Klippen Belt (Carpathians). Acta Geol.
Polon., 27, 3, 387-400.
MARSHAL D. J. 1988. Cathodoluminescence of Geological Materials. Unwin Hyman Ltd.