GEOLOGICA CARPATHICA, 53, 5, BRATISLAVA, OCTOBER 2002
283 — 294
PALEOMAGNETIC AND ROCK MAGNETIC PROPERTIES
OF THE LOWER PALEOZOIC METAMORPHIC COMPLEX
OF THE RUDAWY JANOWICKIE (WEST SUDETES, POLAND)
, TOMASZ WERNER
and STANISŁAW MAZUR
Institute of Geophysics, Pol. Ac. Sc., Ks. Janusza 64, 01-452 Warsaw, Poland; *firstname.lastname@example.org
Institute of Geological Sciences, University of Wrocław, Pl. Borna 9, 50-204 Wrocław, Poland
(Manuscript received July 24, 2001; accepted in revised form June 18, 2002)
Abstract: The Lower Paleozoic Rudawy Janowickie Metamorphic Complex represents the eastern part of the Izera-
Karkonosze Massif in the West Sudetes (NE Bohemian Massif). It comprises a nappe pile overthrust towards the NW
onto the pre-Variscan continental basement of the Saxothuringian Basin. The complex consists of three units: (1)
Leszczyniec Unit composed of metabasites and gneisses, (2) Izera-Kowary Unit consisting of gneisses and mica schists
and (3) the South Karkonosze (Niedamirów) Unit consisting of greenstones and phyllites. These rocks underwent multi-
stage deformation mostly accompanied by epidote-amphibolite grade metamorphism of the Late Devonian to Early
Carboniferous age. Rock magnetic study revealed magnetite and hematite as carriers of remanence accompanied by
maghemite and sometimes by goethite. Several high stability components of characteristic remanent magnetization
(ChRM) of predominantly reversed polarity were found. The shallow directions of remanence were interpreted as Car-
boniferous overprint on the basis of the similarity of their pole position to the Carboniferous segment of the Apparent
Polar Wander Path (APWP) for Baltica. The position of paleopoles derived from the steep directions corresponds well
with the Silurian segment of the APWP for Baltica assuming the anticlockwise rotation of the Rudawy Janowickie
Complex by the angle of ca. 90°. The paleolatitude derived from these directions after averaging corresponds well to the
Silurian data for the Bohemian Massif. The possibly Early Paleozoic directions were found in different rock types:
metabasites, gneisses and limestones from the Leszczyniec and Izera-Kowary Units. However, the scatter of the Kmax
and ChRM along similarly oriented girdles may suggest that the deformation influenced the NRM directions.
Key words: Paleozoic, metamorphic complex, paleomagnetism, rock magnetism.
The West Sudetes lying on the NE margin of the Bohemian
Massif shows complex geology consisting in a mosaic of dis-
tinct, fault bounded, pre-Permian basement units. Several re-
cent interpretations invoke a number of variously defined tec-
tonostratigraphic terranes in the West Sudetes, either showing
close affinities to the major tectonic zones of the Variscan
Orogen (e.g. Matte et al. 1990) or, at least in part, exotic with
respect to the Variscan belt (e.g. Cymerman et al. 1997). The
space for conflicting tectonic hypothesis partly emerges from
the scarcity of paleomagnetic data for the pre-Permian, mostly
metamorphosed rock complexes of the West Sudetes. The pre-
liminary studies generally revealed the paleomagnetic poles
representing Carboniferous and Permian overprints (e.g.
Jeleńska et al. 1995; Kądziałko-Hofmokl & El-Hemaly 1997;
Edel et al. 1997). Some other results (Nawrocki &
Żelaźniewicz 1996; Kądziałko-Hofmokl et al. 1998) suggest
the presence of characteristic directions with their poles locat-
ed on the Early Paleozoic segment of the Apparent Polar Wan-
der Path (APWP) for Baltica and Eastern Avalonia. The latter
data, however, seem to be not fully consistent with the avail-
able geological evidence (e.g. Aleksandrowski et al. 2000).
The paleomagnetic study of non-metamorphosed Devonian
olistoliths from Early Carboniferous wild-flysch succession
(Jeleńska et al. 2001) documented pre-folding remanence
component corresponding to the paleolatitude characteristic
for the southern margin of Baltica in the Devonian. It dates
back, however, only to Middle-Late Devonian times that is to
the interval contemporaneous with the initial accretion of the
Variscides. Consequently, preceding results are still very in-
sufficient and require additional verification through more
specific investigations in particular units of the Variscan base-
ment of the Sudetes.
This paper discusses the results of the paleomagnetic study
in the Rudawy Janowickie Metamorphic Complex, being a
part of the Karkonosze-Izera Massif in the West Sudetes. The
present work is a continuation of magnetic anisotropy and
structural investigations of that area carried out by Werner et
al. (2000). It also refers to the earlier paleomagnetic results of
Kądziałko-Hofmokl et al. (1998) which were only limited to
the Paczyn gneisses (locality LPC in this paper). The aim of
the study is to put new constraints on the tectonic evolution of
the metamorphic complex of the Rudawy Janowickie on the
basis of paleomagnetic data and analysis of relationships be-
tween deformation, tectonic and magnetic anisotropy and pa-
The Rudawy Janowickie Complex belongs to the
Karkonosze-Izera Massif which occupies the south-central
part of the West Sudetes on the NE margin of the Bohemian
Massif (Fig. 1). The massif comprises the Early Carboniferous
Karkonosze granite pluton surrounded by its Neoproterozoic-
284 JELEŃSKA, WERNER and MAZUR
PALEOMAGNETIC AND ROCK MAGNETIC PROPERTIES OF THE METAMORPHIC COMPLEX 285
Paleozoic metamorphic envelope. The latter consists of sever-
al structural units showing different lithostratigraphy and
metamorphic evolution (Mazur & Aleksandrowski 2001).
From base to top these units are: (1) the Izera-Kowary, (2)
Ještěd, (3) South Karkonosze and (4) Leszczyniec. The Izera-
Kowary Unit is mainly composed of the ca. 500 Ma old (Oliv-
er et al. 1993; Kröner et al. 2001) Izera granite, most of it
transformed by a subsequent deformation into the Izera (or
equivalent Kowary) gneiss, and of mica schists representing
remains of its Neoproterozoic(?) envelope. These rocks under-
went medium-pressure (MP) metamorphism under upper
greenschist—lower amphibolite facies conditions (Kryza &
Mazur 1995; Oberc-Dziedzic 1987). The mica schists are in
places associated with bands of stripe metabasites character-
ized by within-plate geochemical signature (Winchester et al.
1995). The Ještěd Unit comprises shelf and continental slope
sediments of Devonian to Early Carboniferous age only sub-
jected to lower greenschist facies conditions. The South
Karkonosze Unit consists of Lower Paleozoic variegated
metasediments and MORB (Mid-Ocean Ridge Basalt) type
metabasites. These rocks bear record of blueschist facies meta-
morphism overprinted by the medium-pressure greenschist fa-
cies event. The Leszczyniec Unit comprises a differentiated
suite of mafic and felsic rocks of volcanic and plutonic origin.
The most widespread rock type is fine-grained MORB-type
schistose metabasite associated with minor medium-grained
massive varieties and with thin intercalations of felsic
metavolcanics (Kryza et al. 1995; Winchester et al. 1995).
Their age is estimated as Early Ordovician, ca. 500 Ma
through preliminary U-Pb zircon dating (Oliver et al. 1993).
The metabasites include several large sill-like bodies of the
Paczyn gneiss. The latter comprise a wide range of rock types
from felsic to hornblende-bearing gneisses (Kryza et al. 1995).
The Leszczyniec Unit underwent relatively high pressure (HP)
metamorphism reaching the epidote-amphibolite facies.
The N-S trending Rudawy Janowickie Mts represent the
eastern margin of the Karkonosze-Izera Massif sandwiched
between the Karkonosze granite on the west and Carbonifer-
ous to Lower Permian sediments of the Intra-Sudetic Basin on
the east. The metamorphic complex of the Rudawy Janowic-
kie Mts comprises the eastern margin of the Izera-Kowary
Unit, the entire Leszczyniec Unit and a small fragment of the
South Karkonosze Unit (Fig. 1).
The structural study of the eastern margin of the Karkonosze-
Izera Massif, carried out by Mazur (1995), revealed three main
deformation events D
of regional extent. The D
isode, comprising NW-directed ductile thrusting, produced the
main foliation S
and mostly NW-SE trending stretching linea-
with local relics of top-to-the NW shear indicators. The
stretching lineation in the Leszczyniec Unit is NNE-SSW-
oriented and, thus, it differs from the general trend of L
neighbouring units. The NW-ward nappe stacking was followed
by SE-directed Visean extensional collapse D
. The L
ing lineation trends WNW-ESE throughout the entire
Karkonosze-Izera Massif. Numerous kinematic indicators con-
sistently show a top-to-the ESE sense of shear. The important
reorientation of the regional foliation on the eastern margin of
the Karkonosze-Izera Massif has been attributed to the D
tion around a NNE-SSW trending axis of the so-called East
Karkonosze monocline (Oberc 1960).
The South Karkonosze and Leszczyniec Units are interpret-
ed as nappes, which emplaced blueschist facies rocks and
MORB-type meta-igneous complexes on top of a continental
passive margin (Mazur & Aleksandrowski 2001). Outcrops of
these two nappes are considered to delineate a Variscan suture
zone separating the Saxothuringian passive margin to the NW,
represented by the Izera-Kowary and Ještěd Units, and the
concealed hypothetical active margin of the Tepla-Barrandian
terrane to the SE (Mazur & Aleksandrowski 2001).
The timing of the collision recorded by the Karkonosze su-
ture zone is approximately constrained by the Ar-Ar age of
white micas from the HP rocks of the South Karkonosze
Nappe (Maluski & Patocka 1997). The blueschist facies meta-
morphism, at least partly preceding the collisional event, was
dated at ca. 360 Ma (a minimum age), whereas the age of the
subsequent MP overprint was estimated at ca. 340 Ma. The
time span between 360 and 340 Ma roughly corresponded to
the period of nappe emplacement, since the decompression of
the HP rocks was mostly related to the overthrusting event
(Mazur & Kryza 1996). The final emplacement of the previ-
ously metamorphosed nappes must have post-dated the early
Visean cessation of sedimentation in the Ještěd Succession, as
this weakly metamorphosed sedimentary sequence is overrid-
den by the South Karkonosze Complex. The subsequent exten-
sional collapse took place at around 340 Ma and must have
ceased before the intrusion of the little deformed, mostly post-
orogenic Karkonosze granite, dated at ca. 330—325 Ma
(Duthou et al. 1991). The origin of the East Karkonosze mono-
cline post-dated the D
event and the emplacement of the
Karkonosze granite, since the rotation affected, apart from the
metamorphic complexes of the Rudawy Janowickie Mts, also
the Upper Visean conglomerates of the Intra-Sudetic Basin.
A total of 145 hand samples and 52 drilled cores (Fig. 1)
were collected in 12 localities from the Rudawy Janowickie
8 within the Leszczyniec Unit: LP – metabasite and lime-
stone, LW – metabasite, LWK – metabasite and metaryolite,
LS – metabasite and gneiss, LT – metabasite and gneiss,
OGK –metabasite and gneiss, LPC – gneiss, JK – gneiss.
4 within the Izera-Kowary Unit: KC – schist, KO – stripe
metabasite, PK – gneiss, KL – schist.
1 within the South Karkonosze Unit: NE – greenschist.
Several cylindrical specimens were cut from each hand sam-
ple and one or two cores were obtained from each drilled core.
Magnetic mineralogy was determined by examination of
thin and polished sections under ore microscope and by a set
of thermomagnetic experiments. Several samples were exam-
ined under scanning electron microscope JSM-35 and by
means of microprobe (EDS) LINK-ISIS. The range of magni-
fication used was between 80 and 2500 times.
The thermomagnetic methods used to identify magnetic
minerals comprised: thermomagnetic analysis which consists
of continuous thermal demagnetization of saturation isother-
mal remanence (SIRM), the Lowrie test – step by step ther-
mal demagnetization of three components IRM (Lowrie
1990), changes of magnetic susceptibility during heating-
286 JELEŃSKA, WERNER and MAZUR
cooling cycle (K(T)) and changes of room temperature suscep-
after step by step heating. The structure of the mag-
netic minerals were examined by determination of IRM and
anhysteretic remanent magnetization (ARM) acquisition
curves and hysteresis loop parameters.
Thermomagnetic analysis was made using a home-made de-
vice. A specimen was magnetized in a field of 1 or 9 T using
Fig. 2. Examples of susceptibility during heating K(T) (Figs. a,b,e,g); thermal demagnetization of three-axial IRM (Lowrie test; Figs.
c,f,h); decay of saturation IRM (SIRM) during continuous heating (Fig. d) curves showing magnetite, hematite and goethite for metaba-
sites and gneisses from the Leszczyniec Unit.
MMPM10 of Magnetic Measurements (Liverpool, UK). Then
remanence was measured in a field free space during rotation
of a specimen. Three perpendicular components of remanence
used for Lowrie test were acquired in fields of 3 T, 0.5 T and
0.12 T, respectively. Remanent magnetization was measured
by means of 2G SQUID cryogenic magnetometer and by a
JR4 Czech spinner magnetometer (Agico, Brno).
PALEOMAGNETIC AND ROCK MAGNETIC PROPERTIES OF THE METAMORPHIC COMPLEX 287
Heating was performed in a non-magnetic oven of Magnetic
Measurements (Liverpool, UK). ARM was acquired in a
steady field of 0.05 or 0.1
T and a peak alternating field in-
creasing up to 100 mT in a Czech device LDA1/AMU (Agico,
Brno). The bulk susceptibility measurements were conducted
using KLY-2 Kappabridge (Agico, Brno). Changes of magnet-
ic susceptibility during heating were performed with use of a
KLY-3/CS-3 device (Agico, Brno). Hysteresis loop was mea-
sured using vibrating magnetometer VSM of Molyneaux, UK.
In the metabasites (OGK, LS, LW, LWK, LP, LT) examina-
tion of thin and polished sections revealed the presence of au-
tomorphic magnetite sometimes with thick ilmenite lamellae.
Often magnetite underwent martitization. In the LS pseudo-
Fig. 3. Examples of susceptibility during heating K(T) (Figs. a,f); thermal demagnetization of three-axial IRM (Lowrie test; Figs. c,e);
decay of saturation IRM (SIRM) during continuous heating (Fig. b) and changes of room temperature susceptibility K
after step by step
heating (Fig. d) curves showing magnetite, hematite and goethite for schists and gneisses from the Izera-Kowary Unit.
morphs after Fe-oxides and sulphides were observed. In the
LWK and LP hydrooxides after sulphides were seen. Every-
where magnetite is accompanied by tabular or flaky hematite.
In the gneisses (OGK, JK, LS, LT, LPC) aggregate of hematite
or tabular hematite were observed under a microscope. In LPC
pseudomorphs after magnetite and hydrooxides were seen.
Under the scanning electron microscope, in LS and LW, two
generations of magnetite and flaky hematite were detected.
In the metabasites from the Leszczyniec Unit the main mag-
netic mineral detected by K(T) curves, thermomagnetic analy-
sis and Lowrie test (Fig. 2) is magnetite. Sometimes magnetite
is accompanied by some amount of hematite (Fig. 2b). In the
LS and LW metabasites goethite was seen on the thermomag-
netic curve (Fig. 2d). In the LP, the thermomagnetic and K(T)
curves (Fig. 2d,e) show hematite not seen on Lowrie test
curves (Fig. 2f). We explained this behaviour as due to oxida-
288 JELEŃSKA, WERNER and MAZUR
tion of maghemite to hematite after heating above 300 °C
demonstrated by decrease of susceptibility (Fig. 2e).
In the gneisses mainly hematite was observed (Fig. 2g,h),
sometimes with magnetite (Fig. 2g) and the phase with un-
blocking temperature (T
about 300 °C (Fig. 2h). In the OGK
and JK gneisses, thermomagnetic analysis (Fig. 2d) revealed
the presence of goethite.
In the mica schists and metabasites of the Izera-Kowary
Unit, magnetite was seen under miscroscope only in KL. In
the KO magnetite is replaced by amphibole. In the KL and PK
sulphides and hydrooxides were observed. Under scanning mi-
croscope hematite, hydrooxides and sometimes magnetite
were observed in the KO.
The thermomagnetic analysis and K(T) curves showed mag-
netite in the KO, KL and KC (Fig. 3a,b). The Lowrie test con-
firmed the presence of magnetite in these localities (Fig. 3c).
Sometimes K(T) curves revealed magnetite, an increase of
susceptibility from a temperature of 150 °C followed by a de-
crease from 300 °C and some hematite. Such behaviour often
observed on the K(T) curves (Fig. 3a) can be interpreted as de-
hydration of goethite to maghemite followed by oxidation of
maghemite to hematite. The thermomagnetic analysis (Fig.
3b) revealed the presence of mineral with low unblocking tem-
) seen on all components with T
and 200 °C which can be a goethite as well.
In the PK and KL gneisses the Lowrie test showed hematite,
magnetite and the phase with T
of 200 °C (goethite?), and
sometimes the phase with T
of about 320 °C, which can be
Fig. 4. Examples of ARM (a) and IRM (b) acqusition curves.
related to pyrrhotite (Fig. 3e). The curve of room temperature
susceptibility changes after step by step heating shows increas-
es of susceptibility after heating to 325 °C and after 500 °C,
which can be related to dehydration of non-magnetic hydroox-
ides and to oxidation of pyrite, respectively (Fig. 3d). The
K(T) curves confirmed the presence of hematite (Fig. 3f) in
the PK and KL.
In KC all experiments revealed the presence of magnetite.
For selected samples IRM and ARM acquisition curves
were determined (Fig. 4). The IRM and ARM acquisition
curves are evidence for high coercivity material, although the
coercive force and coercivity taken from hysteresis loops are
not very high (Werner et al. 2000, Table 1). It suggests that the
field of 0.1 T used for hysteresis loop measurements is not suf-
ficient for saturation and we are still dealing with partial loops.
South Karkonosze Unit
In the NE greenschists all experiments pointed to hematite
as the magnetic mineral. The hysteresis parameters and IRM/
ARM acquisition curves showed high coercivity material (10).
Summing up the main magnetic carriers of remanence are
magnetite, hematite and sometimes goethite and maghemite.
Magnetite is often cut by ilmenite lamellae, partly oxidized to
martite or replaced by amphibole. This magnetite is likely to
be primary. Hematite seen under the microscope occurs in the
tabular form or flakes often inside the veins. The tabular or
flaky form can be related to the primary origin. Hematite
placed inside the veins should be of secondary origin.
The results of the anisotropy of magnetic susceptibility
(AMS) study, presented in the paper by Werner et al. (2000),
confirmed that magnetic foliations in both the Izera-Kowary
and the Leszczyniec Units display, besides the minor differ-
ences in dip, approximately similar NNE-SSW striking sub-
vertical orientations. The Kmin axes correlate well with poles
to the S
foliation at the scale of a single locality and the entire
area (Fig. 5a,c). This is only the northernmost edge of the Iz-
era-Kowary Unit where the structural and magnetic foliation
strikes E-W (localities KC and KO).
Werner et al. (2000) demonstrated that the magnetic linea-
tion Kmax and structural stretching lineation L
(Fig. 5b,d) are
steep, mostly WNW-ESE oriented over the Izera-Kowary
Unit. In contrast, the majority of exposures in the Leszczyniec
Unit display distribution of the Kmax along a great circle, cor-
responding to the mean attitude of the magnetic foliation.
There is a full spectrum of transitional orientations between
the NNE-SSW horizontal and WNW-ESE steep structural
trends (L1) characteristic of the Leszczyniec and the Izera-
Kowary Units (Fig. 5d), respectively. A scatter of the magnet-
ic lineation, detected at the scale of individual exposures (i.e.
LPC), precludes rotation of magnetic fabric on the limbs of
map-scale folds. It must have resulted, therefore, from a con-
tinuous change of strain geometry. Consequently, the AMS
data support previous structural observations showing a differ-
ent structural pattern in the Leszczyniec Nappe in comparison
to the underlying tectonic units.
PALEOMAGNETIC AND ROCK MAGNETIC PROPERTIES OF THE METAMORPHIC COMPLEX 289
mgt + goethite
mgt + hem
mgt + hem
mgt + hem
mgt + hem
mgt + hem
mgt + hem
mgt + hem
mgt + hem
mgt + hem
are the bulk susceptibility and paramegnetic susceptibility; M
are saturation magnetization and saturation remanence; H
are coercive force and coercivity.
Fig. 5. Mean values of S1 and poles to L1 (a,b); counting means
for Kmin (c) and counting means for Kmax (d) for localities
(modified after Werner et al. 2000).
Table 1: Hysteresis parameters for selected samples of different lithology (modified after Werner et al. 2000).
The AMS data of Werner et al. (2000) are completed in this
paper with measurements of magnetic remanence anisotropy
(AARM), carried out by imposing anhysteretic remanence
(ARM). The anhysteretic remanence was acquired on a sam-
ple using a commercial AMU-1/LDA-1 device made by Agico
Czech Republic. The ARM acquisition curves made for two
values of DC field: 50 and 100 µT allow us to choose values of
the DC and AF field for ARM acquisition and orientation
scheme for anisotropy determination. We used the DC field of
100 µT and AF field of 90 mT. The 6-directions scheme along
face-diagonals was selected as a fast robust method of the
AARM tensor determination with sufficient accuracy. This
scheme was employed by Agico for AREF software, which
we used for AARM tensor calculation (Jelinek 1981).
The anisotropy of the remanence axes Amax (Fig. 6) are ap-
proximately similar to the AMS axes (Fig. 5) for the Leszc-
zyniec and the Izera-Kowary Units. The subhorizontal NE-
SW orientation of the Amax of the Leszczyniec Unit is better
pronounced than for the AMS. The foliation planes of the
AARM (Figs. 5 and 6) are subvertical and more scattered than
those for the AMS data. The scatter observed for the anisotro-
py of remanence could be caused by the hardness of the rocks
often containing goethite or hematite. The orientation of the
ARM foliation planes in the Izera-Kowary Unit are almost
perpendicular to those in the Leszczyniec Unit. The E-W
strike of the structural and AMS foliation planes in the KO and
KC localities are considered by Werner et al. (2000) as an ef-
fect of their rotation due to a sinistral displacement along the
adjacent Intra-Sudetic Fault. The N-S oriented Amin direc-
tions are, however, well-documented by AARM data not only
in these localities, but also in this part of the Izera-Kowary
Unit (KL and PK) which crops out far away from the fault.
This situation indicates that a growth of ferromagnetic miner-
als, responsible for the anisotropy of remanence took place in
different time than the structural and AMS foliations were cre-
ated. The subhorizontal NE-SW Amax found in the Leszc-
zyniec Unit is probably related to the oldest fabric created dur-
ing NW-directed ductile thrusting and associated with the N-S
trending foliation plane. The steep WNW-ESE structural and
magnetic fabrics well pronounced in the Izera-Kowary Unit
were produced during the extensional deformation D
290 JELEŃSKA, WERNER and MAZUR
Fig. 7. Examples of thermal and AF demagnetization of specimens. Lines represent directions calculated by PDA software of Lewan-
dowski et al. (1997). Directions are plotted in geographical coordinate system by means of the PDA software.
imposed on the original D
fabric in the Leszczyniec Unit. Fer-
romagnetic minerals which are responsible for E-W trending re-
manence foliation of the Izera-Kowary Unit were probably pro-
duced in the extensional regime D
demonstrated by well
developed magnetic lineation overprinted in the Izera-Kowary
Unit on the previously developed N-S trending foliation.
Paleomagnetic measurements were performed by means of
2G SQUID and associated AF demagnetizer. Thermal demag-
netization was carried out in the non-magnetic oven produced
by Magnetic Measurements, U.K. The measurements were
performed in the cage (Magnetic Measurements, U.K) com-
pensating about 95 % of the ambient magnetic field.
AF and thermal demagnetization were performed for pilot
samples from each locality. For part of samples thermal de-
magnetization was not possible to temperatures higher than
500—575 °C (Fig. 7). Above that temperature heating caused
chemical changes in the magnetic minerals and an increase of
remanence was observed. Sometimes chemical changes oc-
curred at low temperature (200—300 °C) which preclude ther-
mal demagnetization. When thermal demagnetization was im-
possible AF demagnetization was applied. AF demagneti-
zation did not remove the remanence completely for the ma-
jority of samples, but the demagnetization path is usually di-
rected to the beginning of the coordinate frame (Fig. 7a,d,f,g).
When the path is not directed to the beginning (Fig. 7c,e) we
loose the final direction. In spite of such difficulties we were
Fig. 6. AARM axes for Leszczyniec unit (upper) and Kowary Unit
(lower). AARMmax (left) and AARMmin (right). Axes for indi-
PALEOMAGNETIC AND ROCK MAGNETIC PROPERTIES OF THE METAMORPHIC COMPLEX 291
Mean of LP2, LWK2, OGK2, LPC2,
KO, KL after corr 1 and 2
D, I — declination, inclination of the ChRM;
, k — Fisher statistics parameters; N — number of directions used;
— latitude and longitude of the south paleopole; “-“ for
south hemisphere. Corr 1 — rotation of all direction except KC and KO around the axis 205°/15° about 35° clockwise. For KC and KO the axis 100°/65° and angle 60° was used.
Corr 2 — rotation of steep directions around the axis 15°/0° about the angle 50°. * — the direction was not considered for further anal
Table 2: ChRM directions for Rudawy Janowickie.
Fig. 8. Distributions on stereonet site-mean directions with
circles (a) and plane fitted to those directions. Plotted by means of the
PDA software of Lewandowski et al. (1997). Plane of Kmax distribution (b).
able to isolate directions of characteristic remanence (CHRM)
of high stability. Characteristic remanence components were
calculated using the PAD package (Lewandowski et al. 1997)
which includes principal component analysis (Kirschvink
1980). Linear segments of demagnetization curves were ac-
cepted for maximum deviation (MAD) of less than 10°. More
than 4 points were used to define a line. Isolated components
were usually removed between 20 and 80—120 mT or at a tem-
perature about 500—575 °C suggesting magnetite as magnetic
carrier. In the case of some samples it is not possible to deter-
mine blocking temperatures as we are not able to complete
thermal demagnetization and only AF treatment was applied.
However, we suppose that the high stability component not re-
moved completely by 120 mT field during AF demagnetiza-
tion is carried by hematite.
The in situ mean directions of high stability for localities are
shown in Fig. 8 and listed in Table 2. For localities: LP, OGK
and LPC two directions were found. Three directions were re-
292 JELEŃSKA, WERNER and MAZUR
vealed in LWK. The in situ mean directions lie along NE-SW
great circle (Fig. 8). Shallow directions of reversed polarity
trending SSW (NE, LP1, LW), slightly steeper directions (LT,
JK, LWK1) and shallow direction of normal polarity trending
NNE (LPC1) are similar to the Late—Middle Carboniferous di-
rections previously reported for Sudetes (Westphal et al. 1987;
Edel et al. 1997; Kądziałko-Hofmokl & El-Hemaly 1997). The
paleopoles derived from these in situ directions (Fig. 9a, Table
2) are placed in the Carboniferous segment of Apparent Polar
Wander Path (APWP) for Baltica constructed by Torsvik et al.
(1992). The paleopoles derived from the directions KC, PK
and LWK3 can be easy interpreted as Permian overprint, al-
though they do not fit exactly the APWP. The steep directions
trending to the N-NW (directions LP, LPC, OGK) or to S-SW
(directions KL, KO, LWK2, LT, OGK1) gave the pole posi-
tions to the north from the Devonian-Silurian boundary, close
to the APWP for Armorica (N-NW directions, LPC2, OGK2,
KO, LP2,) and close to the Early Devonian poles for Baltica
(SW directions, LWK2, OGK1, KL). The directions belonging
to the particular groups do not differ in stability, which is al-
ways very high or by magnetic carrier. They were carried by
magnetite and hematite as well.
Interpretation and discussion
The tectonic evidence from the Rudawy Janowickie Com-
plex indicates its twofold tilting. The SE-directed extensional
resulted in a steep ESE-ward dipping of the re-
gional foliation. The subsequent important reorientation of the
regional foliation was attributed to the rotation D
NNE-SSW trending axis of the East Karkonosze monocline.
Its development must have post-dated the emplacement of the
Karkonosze granite dated at 330—325 Ma and the origin of the
Upper Visean conglomerates of the Intra-Sudetic Basin. Con-
sequently, we corrected all directions to restore their position
before rotation induced by the East Karkonosze monocline.
Furthermore, we took into account that the northernmost edge
of the Izera-Kowary Unit (locatities KC and KO) was rotated
anticlockwise due to a sinistral movement along the Intra-Su-
detic Fault. The correction applied (correction 1) and corrected
directions were listed in Table 2. After the correction, the N-
NW directions yielded poles (LPC2, OGK2, LP2), which lie
close to the 500 Ma poles for Baltica (Table 2). The SW direc-
tions (LWK2, OGK1, KL) and KO yielded poles between the
Late Ordovician poles of Baltica and Armorica. The LT pole
lies in the vicinity of the Lower Silurian and KC in the Middle
Devonian. The changes of the Carboniferous poles are insig-
nificant. Because the regional foliation produced by the D
event was strongly tilted during the D
extensional collapse, the position of poles earlier than Carbon-
iferous should be additionally corrected. After correction for
deformation (correction 2 in Table 2), the LWK3 pole
fell in the Late Devonian segment of the APWP for Baltica
(Fig. 9b). The KC pole was placed at about 415 Ma. The KO,
LP2, OGK2, LPC2, KL, OGK1 and LWK2 poles form a cloud
close to the equator beneath the Ordovician segment of the
APWP for Baltica. The mean of these poles: 2°N, 78°E gives
the paleolatitude 19°S which is the value characteristic for the
Llandoverian up to Emsian position of the southern margin of
Baltica. It suggests the position of the Rudawy Janowickie ad-
jacent to the southern margin of Baltica and large-scale anti-
clockwise rotation of about 90°. This is in agreement with the
Late Silurian pole obtained for the Bohemian Massif by Tait et
Fig. 9. APWP for Baltica on equal area projection (after Torsvik et al. 1992) shown with paleopoles for the Rudawy Janowickie Complex.
(a) in-situ paleopole positions; (b) tilt corrected paleopoles: LW, LP1, LWK1, PK, LPC1, LT, JK and NE – pole positions derived from di-
rections after correction 1 (Table 2); LP2, LWK2, LWK3, OGK1, OGK2, LPC2, KC, KO and KL – pole positions derived from directions
after correction 1 and 2 (Table 2). Plotted by means of the GMAP software of Torsvik & Smethurst (1994).
PALEOMAGNETIC AND ROCK MAGNETIC PROPERTIES OF THE METAMORPHIC COMPLEX 293
al. (1994a). These authors reported the Silurian paleolatitude
of the Bohemian Massif of 23°S and 140° anticlockwise rota-
tion. The rotation of the Rudawy Janowickie Complex should
have taken place between the Middle—Late Silurian and Early
Devonian as the KC pole falls in the 415 Ma part of the
APWP. The rotation of about 10° brought the KC pole to the
Early Devonian position. The previously reported data
(Kądziałko-Hofmokl et al. 1998) from the LPC gneisses after
twofold correction gave the following pole positions: 11°N,
103°E (BE2); 7°S, 62°E (CN) yielding the mean: 2°N, 84°E
very close to the mean of the Rudawy Janowickie: 2°N, 78°E.
The corrected pole A2 from the previous data: 53°N, 54°E
gives the paleolatitude of 67°S close to the rest of Armorica in
the Ordovician and well compared with the 76°S of the Bohe-
mian Massif obtained by Tait et al. (1994b).
Despite the similarity of the paleopole position of the NW
directions to the Ordovician and Silurian poles for Baltica we
treat these directions with caution. There is some evidence
supporting the possibility that the old directions can be pre-
served despite significant Early Carboniferous metamorphism.
The old directions were found in the rocks of different litholo-
gy: metabasites, gneisses and limestones within the Leszc-
zyniec Unit and metabasites (KO) and gneisses (KL) of the Iz-
era-Kowary Unit. The presence of primary magnetite suggests
that such old directions may have been preserved in spite of
the high metamorphism which affected the rocks. On the other
hand, some directions were carried by secondary hematite as
well. The age of the NW directions was not constrained by any
test applied in paleomagnetism. The close position of the
plane of Kmax distribution and the plane of ChRM distribu-
tion (Fig. 8) allows us to suspect that deformation has influ-
enced the NRM directions. The magnetic remanence fabric
carried by the ferromagnetic minerals copies the structural and
AMS fabric, which is evidence of the secondary origin of the
majority of magnetic carriers. On the other hand the structural
and AMS data indicate that the deformation of the Leszc-
zyniec Unit partly preceded the deformation of the Izera-
Kowary Unit. In spite of the different deformation pattern,
however, similar paleomagnetic directions were found in both
1. Magnetic mineralogy study shows magnetite and hema-
tite as the main carriers of NRM associated with maghemite.
Sometimes goethite is recognized. The presence of magnetite
cut by thick lamellae indicates the preservation of primary
magnetite. Magnetic minerals display high coercivity.
2. Demagnetization treatment revealed high stability com-
ponents which fall into two groups. The first group is inter-
preted as a Carboniferous overprint based on the similarity of
their pole position to the Carboniferous segment of the APWP
for Baltica. The second group comprises the steep directions.
The position of paleopoles derived from those directions after
tectonic correction corresponds well to the Silurian segment of
the APWP for Baltica, assuming the anticlockwise rotation of
the Rudawy Janowickie Complex by the angle of ca. 90°. The
paleolatitude derived from these directions correspond well to
the Silurian data obtained by Tait et al. (1994a) for the Bohe-
3. The steep potentially Early Palaeozoic directions were
found in different lithologies: metabasites, gneisses and lime-
stones within the Leszczyniec and Izera-Kowary Units. How-
ever, the scatter of Kmax and ChRM along similarly oriented
girdles may suggest that the deformation influenced the NRM
Acknowledgments: We acknowledge the support of the Pol-
ish State Committee for Scientific Research Grant No 9T12B
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