GEOLOGICA CARPATHICA, 48, 6, BRATISLAVA, DECEMBER 1997
353–359
THE EVOLUTION OF THE NEOGENE VOLCANISM
IN THE APUSENI MOUNTAINS (RUMANIA):
CONSTRAINTS FROM NEW K-Ar DATA
EMILIAN RO U
1
, ZOLTAN PÉCSKAY
2
, AVRAM TEFAN
1
, GHEORGHE POPESCU
1
,
CRISTIAN PANAIOTU
3
and CRISTINA E. PANAIOTU
3
1
Geological Institute of Rumania, Caransebe 1, 78344 Bucharest, Rumania
2
Institute of Nuclear Research, Hungarian Academy of Sciences, P.O. Box 51, 4001 Debrecen, Hungary
3
University of Bucharest, Bălcescu 1, 70111 Bucharest, Rumania
(Manuscript received January 9, 1997; accepted in revised form October 15, 1997)
Abstract:
New K-Ar data from the Apuseni Mountains Neogene volcanic area are presented. When combined with
geological and magnetic polarity data, the new data clarify the duration and evolution of this volcanic area. They
show that the Neogene volcanic activity took place during the Late Badenian–Pannonian (15–7 Ma). The beginning of
calc-alkaline andesitic volcanism (around 15–13 Ma) had an explosive character giving a widespread volcano-sedi-
mentary formation. The volcanic activity reached the paroxysm during the Sarmatian (13.5–11 Ma), when thick lava
flows and large volcanic structures were emplaced. This activity decreased in the Pannonian (10–7 Ma) and was
restricted to the central and northeastern parts of the studied area. In the central part, the volcanic activity stopped in
the Early Pannonian (10 Ma), while in the northeastern part it lasted until the Late Pannonian (7 Ma). The volcanic
products are covered by pure sedimentary formations in only a few parts of the area. During all this time, tectonic
activity played an important role in the basin’s development and volcanic processes.
Key words:
Rumania, Apuseni Mountains, Neogene, andesite, K-Ar data, paleomagnetism.
Introduction
The Apuseni Mountains is an isolated massive inside the
Carpathian arc (Fig. 1). They had a complex geological his-
tory and a different evolution with respect to the Eastern and
Southern Carpathians at least before the Tertiary. The Tertia-
ry evolution is characterized by the formation of small intra-
montane basins associated with important volcanic activity.
For many years, the age of these volcanic products was es-
tablished using geometric relationships, lithofacies correla-
tion, or biostratigraphy of the associated sedimentary depos-
its. Significant contributions on these topics were made by:
Ghi ulescu & Socolescu (1941), Cioflica et al. (1966, 1968),
Berbeleac (1966), Antonescu & Mantea (1966), Borco &
Mantea (1968), Sagatovici (1968), Sagatovici & Ionesi
(1971), Sagatovici & Anastasiu (1972), Istocescu (1971) and
Ianovici et al. (1969, 1976).
The first K-Ar data on Tertiary volcanic rocks from the
Apuseni Mountains (Lemne et al. 1983) marked an important
point for the further evolution of models of the magmatic ac-
tivity (Borco et al. 1986, 1989), but some of that data are
unacceptable due to the use of an incorrect isochron method.
Recently, new good quality K-Ar data from the Apuseni
Mountains and some regional correlation of the Neogene
volcanic products were published (Ro u et al. 1995; Pécskay
et al. 1995a, b). In this study, new uniformly distributed K-
Ar ages together with geological background and paleomag-
netic data from Neogene volcanic activity of the Apuseni
Mountains are correlated and discussed with respect to the
evolution of other areas from the Carpatho-Pannonian realm.
Geological settings
The Neogene-Quaternary volcanic activity in the Apuseni
Mountains (Fig. 1) took place in three tectonic units: Internal
Dacides (in Northern Apuseni Mountains), Transylvanides
(in Southern Apuseni Mountains) and Median Dacides (in
the southernmost part of the studied area).
The main tectonic structure of the actual Apuseni Mountains
was established during the Laramic phase, after which a mo-
lasse formation of Maastrichtian–Paleocene age was deposit-
ed. It is composed of polymictic conglomerates, sandstones
and red shales with alluvial origin, sometimes interbedded
with andesites and rhyodacites. This formation was formerly
considered of “Tortonian” age (Ghi ulescu & Socolescu 1941)
and the volcanic rocks were attributed to the first cycle of the
Neogene volcanism (Rădulescu & Borco 1967; Ianovici et al.
1976). Using K-Ar dating on andesites and rhyodacites
(Lemne et al. 1983) and new geological data, the age was
proved to be Maastrichtian-Paleocene (Borco et al. 1989). In
the Hăr ăgani area, the rhyolites — also thought to belong to
the first cycle of Neogene volcanism, show a Lower Creta-
ceous age (124 Ma, Ro u & tefan, pers. commun.).
Between the Maastrichtian–Paleocene molasse deposits and
the Miocene ones, there is an important sedimentation gap,
due to the tectonic uplift of the whole area. During the Lower
Miocene, the main tectonic feature was block faulting, associ-
ated with extensions and a strike-slip regime in the Carpatho-
Pannonian realm. This regime has created small intramontane
basins with temporally independent sedimentologic evolution.
In connection with these basins and surrounding areas, a dis-
354 RO U et al.
persed Neogene volcanic activity took place. For these rea-
sons, we split the studied area in seven zones (Fig. 2): A
(Zarand), B ( ebea-Brad), C (Hăr ăgani-Săcărâmb), D (Deva),
E (Zlatna), F (Ro ia Montană-Bucium), G (Baia de Arie ).
Sedimentary deposits
1. Lower Miocene
sedimentary deposits now have a limited
occurrence in the C zone, near the Hăr ăgani locality. These
deposits compose a finning upward siliciclastic unit (begin-
ning with friable conglomerates and grading up to shales)
which has a transgressive character. There is no direct bios-
tratigraphic control in these deposits, but they are covered
without a significant discontinuity by the Langhian marls.
2. Middle Miocene
sedimentary deposits cover a larger
area (A, B, C, E zones) and consist of pelagic marls with
Globigerina
(Early Langhian, Cioflica et al. 1966), bioclastic
limestones, rhyodacitic tuffs (as ash fall deposition in a distal
facies), gypsum layers, and finally thin bedded radiolarites
(Early Kossovian, Borco et al. 1986).
3.
A volcano-sedimentary formation of Kossovian – Ear-
ly Volhynian age (Cioflica et al. 1968; or only Kossovian in
the Zlatna area, Borco et al. 1986) occurs in A, B, C, E and
F zones. In this interval due to an active tectonic block
movement, each small basin had its own evolution. For ex-
ample, in the C zone (Hăr ăgani-Săcărâmb area) and partially
in B and E zones, the volcano-sedimentary formation con-
sists of silty shales, marls with Spirialis (showing a marine
influence) and sandstones associated with pyroclastic rocks.
The pyroclastic components are dominated by lithoclasts of
quartz-hornblende-biotite andesites. In the F zone, the volca-
no-sedimentary formation was affected by explosive process-
es during the emplacement of the rhyodacites. A specific fea-
ture of the volcano-sedimentary formation appears in the
zone A (Zarand Basin), where two different lake facies oc-
cur. In the eastern part, at the base of the Tălagiu volcanic ed-
ifice, pyroclastic rocks (amphibole-pyroxene andesites) with
large vegetal fragments appear. In the western part (Mini ),
the basal part of the sequence is dominated by pyroclasts of
amphibole-pyroxene andesites mixed with bioclasts (Late
Kossovian), while on the top diatomites are associated with
Fig. 1.
Location of the Neogene volcanic area from the Apuseni Mountains (box) in the Carpatho-Pannonian region. Areas with coeval
volcanic activity: CS — Central Slovakia; TM-Tokaj-Milic-Zemplin; SV—Slanske Vrchy; TR—Transtisza Region; OG—Oa -Gutâi;
AM
—Apuseni Mountains. Age of volcanic activity (in Ma) after Pécskay et al. (1995a). Tectonic units (Săndulescu, 1984): 1—Internal
Dacides; 2—Transylvanides; 3—Măgura Units; 4—undifferentiated Middle, Marginal and Outer Dacides; 5—Moldavides; 6—Neogene
volcanics.
THE EVOLUTION OF THE NEOGENE VOLCANISM IN THE APUSENI MOUNTAINS (RUMANIA) 355
pyroxene andesites prevailing pyroclastic rocks (Early Vol-
hynian, Sagatovici & Anastasiu 1972).
Volcanic products
The volcanic products are mainly calc-alkaline andesites
in composition and have different structures varying from
lava flows, complex stratovolcanoes, and dykes, to intrusive
bodies with a subvolcanic character. Often these products are
intensely affected by hydrothermal alterations.
In the A zone, lava flows alternating with pyroclastic ex-
trusions formed a stratovolcanic structure, composed of py-
roxene andesites and amphibole-pyroxene andesites. In the
B, C, D, E zones the volcanic products are dominated by
small intrusive bodies. Lava and pyroclastic flows occur only
locally. Their composition is mainly constituted by quartz-
amphibole-biotite±pyroxene andesites or by amphibole-py-
roxene andesites. In the C zone at Hăr ăgani (Zâmbri a Hill)
and Săcărâmb (Pârâul lui Toader) two small bodies with
more alkaline composition outcrop.
Volcanic products, in the Ro ia Montană-Bucium area (F
zone) are represented by intrusive bodies (sometimes with
intrusive-explosive breccia) and some pyroclastic material
with a wide range of compositions: rhyodacites dacites,
quartz-amphibole-biotite andesites, amphibole-pyroxene
andesites and basaltic andesites. The two small bodies from
Detunata, consisting of basaltic andesite with long columnar
feature, represent the last volcanic products in this area.
In the G zone, only intrusive bodies appear. They consist
of quartz-amphibole-biotite andesites associated with miner-
alized intrusive breccia and amphibole-pyroxene andesites
often with a megaporphyric texture.
Post-volcanic sediments
The main character of these formations is the absence of any
pyroclastic material. They do not have a large areal extension,
because even after the emplacement of the volcanic products,
the block assemblage still functioned, leading to the formation
of small asynchronous basins. In the Zarand Basin (A zone),
the volcanics are covered first by epiclastic sediments (sands,
marls) and bioclastic limestones of Late Volhynian age (Saga-
tovici 1968; Sagatovici & Ionesi 1971) and later, more extend-
ed (including also the B zone) by Pannonian-Pontian and Qua-
ternary deposits. Around Deva town (D zone), the sediments
have Volhynian–Late Bessarabian age (Lupu et al. 1982). In
the eastern and northeastern part (E, F, G zones) there are no
relations with younger sedimentary deposits.
Fig. 2.
Sketch map of Neogene volcanic rocks in the Apuseni Mountains and location of analyzed samples. K-Ar ages are in Ma. Paleo-
magnetic sites: solid squares—normal polarity; open squares—reversed polarity. Sampling areas: A—Zarand; B— ebea–Brad; C—
Hăr ăgani–Săcărâmb; D—Deva; E—Zlatna; F—Ro ia Montană–Bucium; G—Baia de Arie . Geological symbols: 1—volcano-sedimen-
tary formation; 2—rhyodacites; 3—quartz-amphibole-biotite-pyroxene andesites; 4—amphibole andesites; 5—amphibole (brown)
andesites; 6—basalts; 7—pyroxene andesites; 8—alkaline rocks.
356 RO U et al.
Methods
Measurement of K-Ar ages was carried out in the Institute
of Nuclear Research of the Hungarian Academy of Sciences
Debrecen, Hungary. All the K-Ar ages were measured on
whole rock samples because of the mineralogy and texture of
the magmatic rocks. The samples were degassed in a conven-
tional extraction system using induction heating and were
measured by mass spectrometric isotope dilution with a
38
Ar
spike. The recording and evolution of the Ar spectrum were
controlled by microcomputer. Potassium analyses were made
using standard flame photometric techniques. The K and Ar
determinations were checked regularly against interlaborato-
ry standards. Atomic constants suggested by Steiger & Jäger
(1977) were used for calculating the age. All analytical errors
represent one standard deviation. Details of the instruments,
the applied methods and results of the calibration have been
described elsewhere (Balogh 1985). For stratigraphic classi-
fication, we use the internationally accepted time scale com-
piled for Central Paratethys by Vass & Balogh (1989).
Results and discussions
The sample locations are presented in Fig. 2 and the results
of the K-Ar age determination are given in Table 1. These
ages are represented in Fig. 3 together with the geological
constraint for the ages.
The starting point of the volcanic activity in the Apuseni
Mountains is around Early Kossovian, and the products are
mainly volcano-sedimentary deposits. From the K-Ar ages,
these deposits are synchronous with the emplacement of some
intrusive bodies in the B and F zones: at Curechi (B zone)
14.7±1.7 Ma and at Bucium (F zone): 14.6±1.6 Ma, 14.7±0.8
Ma. Unfortunately, these bodies have no relationship with the
volcano-sedimentary formation. The confidence limit of the
K-Ar data for these rocks is so large (1.6–1.7 Ma) mainly be-
cause the rocks are propilitized. In other areas there are volca-
nic bodies direct related to the volcano-sedimentary formation
and their K-Ar ages agree with the biostratigraphic data. For
example in the F zone, the volcano-sedimentary formation is
pierced by the Brazi dacitic body (13.5±1.1 Ma) and in the
central part (B, C, E zones) is pierced or covered by the
quartz-amphibole-biotite±pyroxene andesites of: 13.6±0.9 Ma
at Săcărâmb, 12.9±0.5 Ma at Brad (Lemne at al. 1983).
After deposition of the volcano-sedimentary formation in
A, B, E and F zones, the amphibole andesites or amphibole-
pyroxene andesites volcanic activity followed. Their K-Ar
ages are in agreement with biostratigraphic markers: Vol-
hynian in Zarand area (13.4±1.2 Ma), Middle Sarmatian in
Brad area (12.4±1.2 Ma) and in Zlatna area (12.6±0.5 Ma).
Around Deva (D zone) the amphibole-biotite andesites
(11.9±0.5 Ma) are intruded by microdiorites (12.1±0.5 Ma)
having the same composition. The two data overlap with
each other, suggesting the short time span between the two
volcanic events. These data agree with the age of the post-
volcanic sedimentary cover (Volhynian–Early Bessarabian,
Lupu et al. 1982). In the same area, some subvolcanic bodies
consisting of amphibole andesites with megaporphyric tex-
ture have a K-Ar age of 12.8±0.5 Ma.
K-Ar data from B and C zones, taken from quartz-amphib-
ole-biotite±pyroxene andesites (“Cetra type”) show a Late
Sarmatian–Early Pannonian age: 11.7±0.5 Ma, 11.2±0.9 Ma
and 10.7±0.4 Ma.
The last volcanic products are asynchronously distributed in
the whole studied area and they are represented by different
petrotypes. In the Zarand area (A zone), the last products are
pyroxene andesites: 13.0±0.7 Ma; 12.8±0.6 Ma; 12.4±0.7 Ma
and they are covered by Upper Volhynian sediments. In the B
zone, the pyroclastic deposits with clasts of quartz-amphibole-
biotite±pyroxene andesites are the final phases of volcanic ac-
tivity here (10.7±0.4 Ma). In Hăr ăgani–Săcărâmb area
(C zone) the volcanic activity stopped in the Early Pannonian
with trachy-andesites (Zâmbri a Hill 10.5±0.4 Ma). In F and
G zones, the last phase of volcanic activity is dominated by
amphibole-pyroxene andesites (with brown hornblende). Their
K-Ar ages group around two intervals: 9–10 Ma and 7–8 Ma.
This type of andesite with brown hornblende was used for a
long time as a marker to identify the final stage of the volcanic
activity in the Metaliferi Mountains (Rădulescu & Borco
1967; Ianovici et al. 1969, 1976). Our K-Ar ages show that
this is no longer true since the same type of andesite also oc-
curred in the first stages of the volcanic activity: 13.4±0.6 Ma
in Zarand area, 12.5±0.6 Ma in ebea–Brad area. In F zone, a
short time after these andesites, the volcanic activity stopped
with the basaltic andesites from Detunata (7.4±0.3 Ma).
Fig. 3.
Distribution of K-Ar data in the Apuseni Mountains and
their stratigraphic confinement. Geological constrains for the age
of the volcanism: 1—pre-volcanic sedimentary deposits; 2—vol-
cano-sedimentary formation; 3—post-volcanic sedimentary de-
posits. Petrotypes: solid diamond—pyroxene andesites; solid in-
verse triangle—amphibole-pyroxene andesites; open inverse
triangle—amphibole(brown)-pyroxene andesites; open circle—
quartz-amphibole-biotite-pyroxene andesite; solid circle—am-
phibole-biotite andesite; star—trachyandesites; solid square—dac-
ites; open square—basaltic andesites. Period: Ka—Karpatian;
Bd—Badenian; Sm—Sarmatian; Pn—Pannonian; Lan—Langhian;
Kos—Kossovian; Vol—Volhynian; Bs—Bessarabian.
THE EVOLUTION OF THE NEOGENE VOLCANISM IN THE APUSENI MOUNTAINS (RUMANIA) 357
No
Sample
Locality
Rock type
K(%)
40
Ar
rad
(%)
40
Ar
rad
(ccSTP/g)
K-Ar age(Ma)
A. Zarand
1*
2688
Dieci
α
px am
1.01
16.2
5.293
×
10
-7
13.4±1.2
2*
2686
Talagiu
α
px am (br)
1.27
48.6
6.623
×
10
-7
13.4±0.6
3*
2685
Camna
α
px
1.22
33.7
6.195
×
10
-7
13.0±0.7
4*
2687
Chiºindia
α
px
1.18
43.3
5.897
×
10
-7
12.8±0.6
5*
2684
Miniº
α
px
1.27
28.3
6.144
×
10
-7
12.4±0.7
B. Þebea-Brad
6*
3352
Curechi
α
am px
1.18
12.2
6.757
×
10
-7
14.7±1.7
7*
2683
Barza
α
am px
1.44
14.4
6.977
×
10
-7
12.4±1.2
8*
3356
Caraciu
α
am(br) px
0.97
34.7
4.714
×
10
-7
12.5±0.6
9*
2682
Brad
α
q am bi ± px
1.22
54.4
5.096
×
10
-7
10.7±0.4
C. Hãrþãgani -Sãcãrâmb
10
3357
Duba
α
q am bi ± px
1.19
18.9
5.210
×
10
-7
11.2±0.9
11
3501
Cetraº
α
q am bi ± px
1.05
51.5
4.793
×
10
-7
11.7±0.5
12*
3350
Zâmbriþa
trachyandesite
2.46
61.7
1.011
×
10
-7
10.5±0.4
D. Deva
13
3524
Nucet
α
am ± bi
1.40
71.0
6.482
×
10
-7
11.9±0.5
14
3525
Pârâul Bãilor
md am ± bi
1.68
61.8
7.921
×
10
-7
12.1±0.5
15
3526
Serhediu
α
am (gr+ br)
1.14
56.9
5.671
×
10
-7
12.8±0.5
E. Zlatna
16
3527
Trâmpoiele
md am px
1.75
64.7
8.621
×
10
-7
12.6±0.5
F. Roºia Montanã-Bucium
17*
3351
Tãul din Brazi
n
1.25
17.5
6.583
×
10
-7
13.5±1.1
18*
2689
Citera
α
am px
1.21
12.8
6.916
×
10
-7
14.6±1.6
20
3530
Bucium S
md am px
0.94
33.3
5.401
×
10
-7
14.7±0.8
21*
3355
Rotunda
α
am(br) px
1.41
33.7
5.095
×
10
-7
9.3±0.5
22
3502
Geamãna W
α
am(br) px
1.27
55.8
3.883
×
10
-7
7.8±0.3
23*
3349
Detunata
α
b
1.30
37.3
3.602
×
10
-7
7.4±0.3
G. Baia de Arieº
24
3528
Bulzu
α
am br px
1.51
50.2
5.942
×
10
-7
10.1±0.4
25
3503
Surligata
α
am br px
1.20
12.3
3.533
×
10
-7
7.6±0.9
Table 1:
K–Ar datings of Neogene calc-alkaline volcanic rocks in the Apuseni Mountains.
Abbreviations:
α
= andesites;
αβ
= basaltic andesites;
n = dacites; md = microdiorites; q = quartz; am = amphibole (gr = green;
br = brown); bi = biotite; px = pyroxene
*Data from Pécskay et al. (1995b)
Correlation of magnetic polarity data
and K-Ar ages
The distribution of the localities sampled for paleomagnet-
ic studies and their magnetic polarity is presented in Fig. 2.
The paleomagnetic data are from Pătra cu et al. (1994),
Panaiotu et al. (1995). To correlate the observed magnetic
polarities with the polarity time scale (Cande & Kent 1995) a
histogram of K-Ar ages was computed using the method of
Vandamme et al. (1991) (Fig. 4). Each datum is a given unit
weight and represented by a Gaussian distribution with stan-
dard deviation equal to the age uncertainty. This flattens the
large uncertainty data and emphasizes the most precise re-
sults. The histogram represents the sum of all individual
Gaussian distributions. The shape of this histogram reveals
three distinct phases of volcanic activity. In the same figure
the histogram of K-Ar data from Oa -Gutâi area (Pécskay et
al. 1995b) is also represented. The shapes of these histo-
grams show that the time of the main volcanic activity is dif-
ferent even the volcanism covers the same period: Sarma-
tian–Pannonian. This distribution of K-Ar data is also re-
flected in the distribution of magnetic polarity data.
Reinterpreting the paleomagnetic data from Oa –Gutâi
area (Pătra cu 1993), according to the new K-Ar data (Péc-
skay et al. 1995b), is obvious that the strong bias toward nor-
mal polarity for the Pannonian sites correlates with the peak
of the volcanic activity around 10.5 Ma. On the polarity time
scale this peak corresponds to the chron C5n (9.7–10.9 Ma)
with normal polarity, which is long enough to explain the
strong bias towards normal polarity. Sites with reversed po-
larity were found only in the areas with ages around 12–
13 Ma or around 9 Ma, in agreement with the polarity time
scale. In the Apuseni Mountains the distribution of magnetic
polarity data is different. From 29 localities sampled in Low-
er Sarmatian–Lower Pannonian rocks, 15 localities have nor-
mal polarity and 14 localities have reversed polarity
358 RO U et al.
(Pătra cu et al. 1994; Panaiotu et al. 1995). This distribution
of polarity data agrees with the main peak of volcanic activi-
ty during the Sarmatian when there was a relatively high fre-
quency of reversals. The four K-Ar ages from the sites sam-
pled for paleomagnetism have too large uncertainties to
assign each site to a certain subchron on the polarity time
scale. Since the sequence of the volcanic activity in the area
sampled for paleomagnetism cannot be always perfectly
known, it is not possible to establish how many reversals are
present in this area.
The last peak on the histogram corresponds to Late Pan-
nonian. The two sites sampled for both K-Ar data and pale-
omagnetism (Detunata and Geamăna W) have a reversed
polarity. Since the interval of the volcanic activity suggested
by the K-Ar data is dominated by normal polarities, the
most probable interpretation is that the volcanic activity
took place during the chron C3Br (7.1–7.4 Ma) or subchron
C4n.1r (7.5–7.6 Ma).
Conclusions
The present K-Ar data and biostratigraphic data show that
the Neogene volcanic activity in the Apuseni Mountains took
place between Kossovian–Pannonian. The beginning of calc-
alkaline andesitic volcanic activity had an explosive character.
The biostratigraphic age of the volcano-sedimentary formation
range from Early Kossovian–Early Sarmatian in the central
part and Late Kossovian–Early Sarmatian in the Zarand area.
The volcanic activity reached its paroxysm during Early–Mid-
dle Sarmatian. The evolution was relative short in the Zarand
and Deva areas where the volcanism stopped in the Late Sar-
matian. During the Pannonian the volcanic activity decreased
and was restricted to some small areas from the central and
northeastern parts of the studied area. In the central part
( ebea–Brad and Hăr ăgani–Săcărâmb areas) the volcanic ac-
tivity stopped in the Early Pannonian, while in the northeast-
ern part (Ro ia Montană–Bucium and Baia de Arie areas) it
lasted until the Late Pannonian.
The andesitic volcanism from the Apuseni Mountains is
coeval with the volcanic activity from the Western Car-
pathians: Central Slovakia and Tokaj–Milic–Zemplin areas
and from the Eastern Carpathians: Oa –Gutâi area (Pécskay
et al. 1995b). Both K-Ar data and polarity magnetic data
show that the main phase of volcanic activity took place dur-
ing the Sarmatian in the Apuseni Mountains and the Early
Pannonian in the Oa –Gutâi area.
Acknowledgements:
This study was performed according to
the bilateral scientific co-operation between the Hungarian
and Rumanian Academies of Sciences. The K-Ar age deter-
minations were sponsored by the Hungarian National Scien-
tific Research Fund (OTKA), Project No. T 7273. We ac-
knowledged the financial support given by the Geological
Institute of Rumania and by the University of Bucharest.
Drs. Lexa and Balogh are thanked for constructive reviews
of the earlier draft of this paper.
References
Antonescu E. & Mantea G., 1966: The age of pyroclastic rocks
from Ribi a-Valea Bradului, Metaliferi Mountains. D. S. Inst.
Geol.,
LII/1, 185-193 (in Rumanian, English abstract).
Balogh K., 1985: K/Ar dating of Neogene volcanic activity in
Hungary: Experimental technique, experiences and methods
of chronological studies. ATOMIKI report D/1, Debrecen,
277–288.
Berbeleac I., 1966: The age of the Tertiary volcanism from Porcu-
rea-Săli te-Hăr ăgani area, Metaliferi Mountains (in Ruma-
nian with French abstract). D. S. Inst. Geol., LII/1, 11–23.
Borco M. & Mantea G., 1968: The age of the Neogene volcanic
activity in the Ro ia Montană basin. Stud. Cerc. Geol.,
Geofiz., Geogr., Ser. Geol.,
13, 2, 363–376 (in Rumanian,
French abstract).
Borco M., Popescu G. & Ro u E., 1986: Nouvelles donnée sur la
stratigraphie et l’evolution du volcanisme tertiare des Monts
Metalliféres. D. S. Inst. Geol.-Geofiz., 70–71/4, 245–259.
Borco M., Ro u E., tefan A. & Popescu G., 1989: Le volcanism
banatitique des Monts Apuseni (Roumania). XIV
th
Congress
KBGA, Extended Abstracts,
194–197.
Cande S. & Kent D.V., 1995: Revised calibration of the geomag-
netic polarity time scale for the Late Cretaceous and Cenozo-
ic. J. Geophys. Res., 100, B4, 6093–6095.
Cioflica G., Istrate G., Popescu G. & Uduba a G., 1966: Contribu-
tions to the knowledge of the volcanic product’s ages from
Hăr ăgani-Trestia area, Metaliferi Mountains. Stud. Cerc. Geol.,
Geofiz., Geogr., Ser. Geol.,
11, 1, 171–182 (in Rumanian).
Cioflica G., Jude R., Uduba a G., Istrate G. & Popescu G., 1968:
New data about Neogene volcanic products from Băi a-
Săcărâmb area Stud. Cerc. Geol., Geofiz., Geogr., Ser. Geol.,
Fig. 4.
Histograms of K-Ar data from the Apuseni Mountains
(heavy line) and Oa -Gutâi Mountains. Numbering of paleomag-
netic sites according to Table 1: solid square—normal polarity;
open square—reversed polarity. Polarity time scale: black—nor-
mal polarity; white—reversed polarity.
THE EVOLUTION OF THE NEOGENE VOLCANISM IN THE APUSENI MOUNTAINS (RUMANIA) 359
13, 1, 77–92 (in Rumanian, English abstract).
Ghi ulescu T. & Socolescu M., 1941: Etude geologique et miniere
des Monts Metalliféres. An. Inst. Geol. Rom., XXI, 181-463.
Ianovici V., Giu că D., Ghi ulescu T.P., Borco M., Lupu M.,
Bleahu M. & Savu H., 1969: Geological evolution of the Met-
aliferi Mountains. Ed. Acad. Rom., Bucure ti, 1–741 (in Ru-
manian, French abstract).
Ianovici V., Borco M., Bleahu M., Patrulius D., Lupu M., Dimi-
trescu R., & Savu H., 1976: The Geology of the Apuseni
Mountains. Ed. Acad. Rom., Bucure ti, 1–631(in Rumanian,
French abstract).
Istocescu D., 1971: Geological study on the western part of Codru
Moma and Highi Mountains. St. tehn. econ., Sera J, 8, 1–201
(in Rumanian, extended German abstract).
Lemne M., Vâjdea E., Borco M., Tănăsescu A. & Romanescu O.,
1983: Des datation K-Ar concernant surtout les magmatites
subsequentes alpines des Monts Apuseni. An. Inst. Geol.
Geofiz.,
LXI (Trav. XII-eme Congr. Assoc. Geol. Carp.-
Balk.), 375–386.
Lupu M., Kräutner H., icleanu N. Bo tinescu S., Bandrabur T.,
Kräutner F., Horvath A.R. & Nicolae I., 1982: Geological
map 1:50,000, Deva Sheet. I.G.R., Bucure ti.
Panaiotu C., Pătra cu S. & Panaiotu C.E., 1995: Paleomagnetism
of Neogene magmatic rocks from the Apuseni Mountains
(Romania). Annales Geophys., Supl. I, 13, C77 (abstract).
Pătra cu S., 1993: Paleomagnetic study of some Neogene magmat-
ic rocks from the Oa -Igni -Văratec- ible Mountains (Roma-
nia). Geophys. J. Inter., 113, 215–224.
Pătra cu S., Panaiotu C., eclăman M. & Panaiotu C. E., 1994:
Timing of the rotational motion of Apuseni Mountains (Ro-
mania): Paleomagnetic data from Tertiary magmatic rocks.
Tectonophysics,
233, 163–176.
Pécskay Z., Lexa J., Szakács A., Balogh K., Seghedi I., Konečný V.,
Kovacs M., Márton E., Kaličiak M., Széky-Fux V., Poka T.,
Gyarmati P., Edelstein O., Ro u E., & Zeč B., 1995a: Space and
time distribution of Neogene-Quaternary volcanism in the Car-
patho-Pannonian Region. Acta Vulcanol., 7, 2, 15–28.
Pécskay Z., Edelstein O., Seghedi I., Szakács A., Kovacs M., Cri-
han M. & Bernad A., 1995b: K-Ar datings od Neogene-Qua-
ternary calc-alkaline volcanic rocks in Romania. Acta
Vulcanol.,
7, 2, 53–61.
Rădulescu D. & Borco M., 1967: Spätsubsequenter alpiner Mag-
matismus in Rumänien. Acta. Geol. Acad. Sci. Hung., 11, 1–3,
139–152.
Ro u E., tefan A., Pécskay Z. & Popescu G., 1995: New data con-
cerning the evolution of Neogene volcanism in the Apuseni
Mountains. Abstracts X
th
R.C.M.N.S. Congress, Rom. J.
Stratigraphy
, 76, Suppl. 7, 2, 47–48.
Sagatovici A., 1968: The Sarmatian from the eastern part of the
Zarand Basin. Anal. Univ. Bucure ti, Seria Geologie, XVII, 2,
55–69 (in Rumanian, French abstract).
Sagatovici A. & Ionesi B., 1971: Sarmatian deposits from Mini ul
de Sus-Chi india, Zarand Basin. Anal. Univ. Bucure ti, Seria
Geologie
, XX, 93–106 (in Rumanian, French abstract).
Sagatovici A., & Anastasiu N., 1972: Pyroclastites from Mini u de
Sus, Zarand Basin. Anal. Univ. Bucure ti, Seria Geologie,
XXI, 31–41 (in Rumanian, English abstract).
Săndulescu M., 1984: Geotectonics of Romania. Tehnică,
Bucure ti, 1–335 (in Rumanian).
Steiger R.H. & Jäger E., 1977: Subcommission on geochronology:
convention on the use of decay constant in geo- and cosmo-
chronology. Earth Planet. Sci. Lett., 36, 359–362.
Vandamme D., Curtillot V. & Besse J., 1991: Paleomagnetism and
age distributions of the Deccan Traps (India): Results of a
Nagpur-Bombay traverse and review of earlier work. Rev.
Geophys.,
29, 2, 159–190.
Vass D. & Balogh K., 1989: The period of Main and Late Alpine
Molasses in the Carpathians. Z. Geol. Wiss., 17, 849–858.