GEOLOGICA CARPATHICA, OCTOBER 2006, 57, 5, 397—403
Provenance of Würmian loess and loess-like sediments of
Moravia and Silesia (Czech Republic): a study of zircon
typology and cathodoluminiscence
and PAVEL UHER
Institute of Geology, Academy of Sciences of the Czech Republic, Rozvojová 269, 165 02 Praha 6, Czech Republic; firstname.lastname@example.org
Department of Mineral Deposits, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovak Republic; email@example.com
(Manuscript received March 7, 2005; accepted in revised form December 8, 2005)
Abstract: A detailed zircon study (typology and cathodoluminiscence) of late Pleistocene (Würmian) loess sediments
from Moravia area, Czech Republic shows a significant western provenance from magmatic (mainly granitic) rocks of
Bohemian Massif together with contributions from metamorphic rocks. Zircon typology is applicable only for well-
preserved magmatic zircon crystals, which usually occupy a part of the whole zircon population. Zircon typology
indicates a dominant provenance from calc-alkaline I-type granites, whereas important contributions of material from
S-type granites (Moldanubian pluton?) is not documented. The provenance material of the Velká Bíteš locality is derived
from the adjacent melanosyenitic rocks (durbachites) of the Třebíč Massif and in this case confirms transport over a short
distance as well as provenance from the west. Cathodoluminiscence images indicate both magmatic and metamorphic
origin of the studied zircon.
Key words: Pleistocene, Würmian, Czech Republic, Moravia, cathodoluminiscence, loess sediments, zircon typology,
Loesses and loess-like sediments occupy large areas, more
than 20 % of the total surface of the Quaternary surface
area in Moravia, the eastern part of the Czech Republic
(Fig. 1). Eolic sedimentation of most of these accumula-
tions is determined during the last Pleistocene glacial age,
Würmian/Upper Weichselian (Frechen et al. 1999). The
average thickness of Würmian loesses is about 1 to 1.5 m.
Würmian loess and loess-like sediments in the Moravia
and Silesia area were studied by many authors. The oldest
studies classified the loesses on the basis of granulometry,
carbonate and humus content. Their provenance was de-
termined mainly according to Quaternary geomorphology
and recent wind directions (Ambrož 1947; Pelíšek 1949).
Later published contributions were based mostly on
stratigraphy or climatology (Musil & Valoch 1956; Ložek
1958; Kukla 1961; Havlíček & Smolíková 1993). In the
last ten years provenance studies have only been carried
out in small areas (Adamová & Havlíček 1997; Frechen et
al. 1999; Adamová et al. 2002; Kvítková & Buriánek
2002; Kvítková & Chadima 2002; Lisá 2004). The most
recent loess study based on heavy mineral associations di-
vided Moravian Würmian loess and loess-like sediments
into five main provenance areas (Lisá 2004; Lisá et al.
The material of Moravian loess sediments is composed
mainly of quartz (Cílek 2001), feldspars, calcite and dolo-
mite (Pécsi 1991). Dominant heavy minerals are represented
by amphibole- and garnet-group minerals (Lisá 2004; Lisá
et al. 2005). Prevailing W, NW and SW winds are docu-
mented by the orientation of loess banks and the presence
of particles from neighbouring rocks. Microstructures of
quartz grains are typical for different regions, where angular
grains are typical for loess from the western part of Moravia
with crystalline basement provenance, whereas more round-
ed grains with fluvial microstructures are common in loess
with a Miocene sediment provenance (Lisá 2004).
Fig. 1. Map of the Quaternary cover with studied localities, aver-
age depth of the cover is 20—40 m (Žebera 1966, modified).
LISÁ and UHER
Results based on the detailed study of heavy minerals,
especially garnet composition, represent a valuable source
for provenance determination (Lisá 2004; Lisá et al.
2005). Zircon typology and cathodoluminiscence are part
of this complex research of Pleistocene loess and loess-
like sediments from Moravia area and the aim of this study
is to contribute to the provenance of loess material using
Samples were collected from typical loess profiles,
which had been described in previous studies (Macoun et
al. 1965; Havlíček 1985; Havlíček & Smolíková 1993;
Adamová & Havlíček 1995, 1997, etc.). Samples are taken
from the Würmian layers, below the 20—60 cm Holocene
layer. In total, 9 localities were selected for detailed zircon
studies and are presented in Fig. 1 and the Appendix.
After sampling and quartation of the loesses, the size
fraction of 0.063—0.250 mm was prepared for heavy min-
eral separation in heavy liquid, tetrabromethane with
D = 2.96 g/cm
. A low-intensity U-shaped magnet was used
to separate ferromagnetic minerals. A final selection of de-
trital zircons was performed by hand picking under the bin-
ocular stereomicroscope and observed in the scanning
electron microscope at the Department of Biology, Masaryk
University, Brno. Observations were evaluated according to
the zircon typology method (Pupin 1980, 1985). One hun-
dred well-developed zircon crystals were used for the typol-
ogy measurements from each studied locality.
Samples for the cathodoluminiscence observations (CL)
were separated by similar methods. Polished samples were
then studied at Dionýz Štúr State Geological Institute,
Bratislava, on the cathodoluminiscence microscope as
part of the Cameca SX 100 electron-microprobe apparatus.
The following analytical conditions were used: accelerat-
ing voltage 8 kV and beam current 1 10
Detritus from Moravian loess and loess-like sediments
contain four main zircon groups: (1) rounded crystals or
Table 1: Distribution of observed zircon subtypes (Pupin 1980) in loess sediments (in %).
fragmented grains, (2) prismatic zircons but with edges
rounded to varying degrees (grains are partly broken, but
without fresh cracks), (3) prismatic zircon with morpholo-
gy not typical for common magmatic rocks, and (4) zircon
with distinct typology characteristic for magmatic rocks
(according to Pupin 1980; Table 1, Figs. 2 and 3).
The amount of magmatic zircon with well-preserved
crystal morphology (population 4) is widely variable (Ta-
ble 1). Rounded zircon crystals without distinctive crystal
faces (groups 1 and 2) are widespread mainly in South-
Moravian loesses (Modřice, Horní Dunajovice, Dolní Věs-
tonice and Ořechov). Only up to 10 % of the zircons have
well-preserved crystal faces applicable for the typology
method. Higher amounts of magmatic well-preserved zir-
con crystals were revealed in the loess sediments from the
northern part of Moravia (Hranice I, Hranice II, Leština
and Osoblaha (15 to 50 %)). Almost 100 % of well-pre-
served magmatic zircon crystals without visible eolic
and/or sedimentary transport features occur in Velká Bíteš
loess in the SW part of Moravia.
Typology results from well-preserved crystals (popula-
tion 4) indicate a relatively uniform distribution of zir-
con types and subtypes for almost all the studied
samples. The S
the most widespread (Table 1, Figs. 2 and 3). Modřice
and Horní Dunajovice localities did not contain suffi-
cient amounts of well-preserved zircons, only scarce S
subtypes in Modřice and S
Horní Dunajovice were observed. On the other hand, dif-
ferent zircon typologies were found in Velká Bíteš loess
sediments, for which S
subtypes are charac-
teristic (Table 1, Figs. 2 and 3).
Zircon from the studied loesses show wide variability of
internal zoning under CL (Fig. 4). A fine regular oscillato-
ry zoning pattern (Fig. 4A,B) is characteristic mainly for
Velká Bíteš, Leština, Osoblaha and Hranice I and II zir-
cons. However, the most widespread pattern is irregular
zoning or complex combinations of regular oscillatory
and irregular zoning; the crystals with oscillatory zoning
are corroded along their rims by younger embayed zones
(Fig. 4C,D) or older oscillatory zonal cores are surrounded
and corroded by rims with irregular zoning (Fig. 4E,F).
This texture is characteristic mainly for the Horní Dunajo-
WÜRMIAN LOESS AND LOESS-LIKE SEDIMENTS OF MORAVIA AND SILESIA: ZIRCON TYPOLOGY
Fig. 2. Typical zircon subtypes (after Pupin 1980) observed in loess sediments.
vice, Modřice, Dolní Věstonice, Hranice I, and Osoblaha
zircon. Rarely, unzonal zircon crystals were found in the
Our results of zircon typology and cathodoluminiscence
revealed some differences in these features as a conse-
quence of various source rocks and provenance areas.
Although zircon typology (Pupin 1980, 1985) was ap-
plied widely as a usefull provenance method for clastic sed-
iments (e.g. Uher & Kováč 1993; Loi & Dabard 1997;
Fekkak et al. 2000; Willner et al. 2003), data from the clas-
tic sediments of the Moravia area are still scarce and incom-
plete (e.g. Král 2002). Moreover, zircon typology is
applicable only for well-preserved euhedral magmatic or
metaigneous zircon crystals, unaffected by extensive sedi-
mentary transport. The presence of common rounded zircon
grains without well-preserved crystal faces indicates a dis-
tinctive pre-eolic sedimentary transport of zircon in clastic
source rocks. However, an irregular oval shape of zircon
could also be a result of metamorphic (re)crystallization
(e.g. Broska & Caňo 1987; Corfu et al. 2003).
The zircon typology of the studied loess sediments
show the clear dominance of zircon subtypes with medium
LISÁ and UHER
I.A. (agpacity index) and medium to high I.T. (index of
temperature) parameters (Fig. 3). Zircon from Dolní Věs-
tonice, Osoblaha, Ořechov, Hranice and Leština reveal
very similar typograms with a majority of medium-temper-
subtypes. Such subtypes
are typical for aluminous to calc-alkaline allanite-bearing
I-type granitic suites rather than lower temperature mona-
zite-bearing S-type suites (cf. Pupin 1985; Broska & Uher
1991). The possible source for such zircons could be mag-
matic suites with I-type character from the eastern part of
the Bohemian Massif, probably from Precambrian mag-
matic rocks of the Brno Massif, eventually from probably
pre-Hercynian granodiorites of Svinov-Vranová Crystal-
line Complex (Dolní Věstonice, Ořechov, Hranice I and
Hranice II loesses). A potential source rock for zircon from
Leština and Osoblaha loesses could be the Šumperk Mas-
sif, a Hercynian allanite-bearing I-type granodiorite (Za-
chovalová et al. 2002). Unfortunately, there are missing
zircon typology data for the above mentioned possible
primary rocks, which would serve as material for compari-
son. Another source for the zircon Leština and Osoblaha
Fig. 3. Zircon typograms (Pupin 1980) for loess sediments.
could be Děsná gneiss, containing partly deformed pre-
On the contrary, zircon typology of the studied Moravi-
an loesses is distinctly different from typology of Hercyn-
ian S- and I-type granitic rocks of the Moldanubian pluton
where low-temperature zircon subtypes dominated (Finger
et al. 1991; Jalovec et al. 1993; Uher et al. 1998). More-
over, in the Moldanubian pluton high-temperature and
(sub)alkaline members occur locally (Karlstift granite;
Finger et al. 1991) or highly-evolved leucogranites with
dominant low-temperature and high-alkaline G
subtype (Homolka granite; Uher et al. 1998), both differ-
ent from loess zircons.
The only unambiguous example represents zircon from
Velká Bíteš loess. Zircon typology shows the dominance
subtypes (Fig. 3), entirely analogous to
zircon typology from the adjacent melanosyenitic rocks
(durbachites) of the Hercynian Třebíč Massif (Holub et al.
1997; Král 2002; Dosbaba & Sulovský 2004).
For provenance studies it is important to distinguish zir-
con derived from magmatic versus metamorphic rocks. It
WÜRMIAN LOESS AND LOESS-LIKE SEDIMENTS OF MORAVIA AND SILESIA: ZIRCON TYPOLOGY
is a complex problem because of similarities in morphology
as well as internal zoning of the magmatic versus metamor-
phic (especially metaigneous) zircon. However, a study of
zircon internal zoning by high-resolution cathodoluminis-
cence (CL) images distinguishes some characteristic pat-
terns of magmatic versus metamorphic zircon. Magmatic
zircons show characteristic fine and regular oscillatory zon-
ing whereas metamorphic zircons reveal irregular zoning,
commonly with the presence of older, partly resorbed or re-
crystallized cores and embayed or mozaic patterns (e.g.
Vavra 1994; Rubatto & Gebauer 2000; Corfu et al. 2003).
The studied zircons from Moravian loesses show both
regular magmatic as well as irregular metamorphic pat-
terns (Fig. 4). The typical fine oscillatory magmatic zon-
ing is characteristic mainly for zircon from Velká Bíteš
loess (Fig. 4A,B) where the adjacent Třebíč melanosyenite
(durbachite) is assumed as the source rock and the zircon
typology clearly supports this.
Fig. 4. Representative CL images of zircons observed in loess sediments. A—D – fine oscillatory zoning, locally with embayments due to
partial resorption (C—D). E – core with regular oscillatory zoning overrimmed by domain with irregular oscillatory zoning. F – irregu-
larly zoned core surrounded by darker rim with irregular zoning. Location: Velká Bíteš (A, B), Dolní Věstonice (C, D), Hranice II (E),
Hranice I (F).
LISÁ and UHER
However, CL images of zircon from other studied loess-
es indicate the presence of both magmatic and metamor-
phic patterns. The common presence of oscillatory zonal
cores corroded by irregular embayed rims indicates post-
magmatic, probably metamorphic processes during zircon
evolution; such patterns were observed mainly in the Dol-
ní Věstonice, Horní Dunajovice, Modřice and Hranice
loesses. Analogous zircon CL patterns were observed from
high-grade metamorphic rocks, such as orthogneisses,
metagabbros, or metasediments (Rubatto & Gebauer 2000;
Corfu et al. 2003). Moreover, results of heavy mineral as-
semblages, especially garnet compositions of the loess, in-
dicates at least a partial metamorphic source of the loess
material, probably from crystalline complexes of the east-
ern part of the Bohemian Massif (Kvítková & Buriánek
2002; Kvítková 2004; Lisá et al. 2005). This assumption
also supports analysis of Würmian winds with prevailing
W, NW and SW directions as documented by loess dune
orientation, the presence of particles from neighbouring
rocks and microstructures of quartz grains (Cílek 2001;
The following main conclusions can be derived from
the presented data:
Zircon typology is applicable only for well-preserved
magmatic zircon crystals, which usually form only a part
of the whole zircon population from Würmian Moravian
loess sediments. The typology of the studied samples indi-
cated dominant provenance of calc-alkaline I-type gran-
ites, probably from various source regions (possibly the
Brno, Svinov-Vranová and Šumperk Massifs), material
from S-type granites (mainly Moldanubian pluton) con-
tributed probably only in negligible amounts.
The provenance material of the Velká Bíteš locality is
significantly different; their zircon population was unam-
biguously derived from the adjacent melanosyenitic rocks
(durbachites) of the Třebíč Massif.
Internal zoning (cathodoluminiscence images) indicates
both magmatic and metamorphic origins of zircon in the
Würmian loess sediments of Moravia.
Generally, zircon typology and cathodoluminiscence
patterns in our study evidently indicate the presence of
magmatic, probably mainly granitic as well as metamor-
phic source rocks for Würmian loesses in the Moravia
area, most probably from Precambrian to Hercynian crys-
talline complexes of the Bohemian Massif. However, some
admixture from younger clastic sedimentary rocks (mainly
Neogene sandstones) in eolic material of Moravian loess
sediments is not excluded.
Acknowledgments: The authors thank František Butula
(Dept. of Biology, Fac. of Sci., Masaryk University, Brno)
and Viera Kollárová (ŠGÚDŠ, Bratislava) for technical as-
sistence on SEM and CL images, Tomáš Navrátil for the En-
glish language corrections, Jaromír Leichmann and two
reviewers for constructive comments. The research was sup-
ported by AVOZ 30130516 Institutional Research Plan.
Appendix: sample location
Osoblaha. NE border of Bohušov village. 2300 m SSW from the
Osoblaha railway station.
Hranice I. Outcrop over “Vápenka“ motorway restaurant;
1500 m SE from the Hranice na Moravě railway station.
Hranice II. Upper part of the Skalka quarry; 2500 m NE from
the Hranice na Moravě railway station.
Leština. E border of the Leština village, 800 m SW from the
elev. point 524, Trlice.
Modřice. 3750 m SE from the elev. point 307, Rovný.
Horní Dunajovice. Centre of Horní Dunajovice village, 950 m
ESE from the elev. point 287, Šibeniční Kopec.
Dolní Věstonice. E border of the Dolní Věstonice village;
2000 m N from the elev. point 550, Děvín.
Ořechov. West border of the Ořechov village; 3000 m SE from
the elev. point 389, Záhumenice.
Velká Bíteš. NW border of the Jestřabí village; 1800 m SSE
from the elev. point 516, Chocholáč.
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