GeolCarp_Vol48_No1_39

GEOLOGICA CARPATHICA, 48, 1, BRATISLAVA, FEBRUARY 1997

39–48

A NEW OCCURRENCE OF TRIASSIC DEPOSITS NE OF ORAVI A

(SOUTHERN CARPATHIANS, RUMANIA)

AND ITS PALEOTECTONIC SIGNIFICANCE

IOAN I. BUCUR

, CAROL STRUTINSKI

and MARIA PAICA

University Babes-Bolyai, Department of Geology-Paleontology, M. Kogalniceanu str.1, 3400 Cluj-Napoca, Rumania

Geological Institute of Rumania, Cluj Branch, CP 181, 3400 Cluj-Napoca, Rumania

FORMIN Caransebes, str. M. Viteazul nr. 1, 1650 Caransebes, Rumania

(Manuscript received June 20, 1996; accepted in revised form December 12, 1996)

Abstract:

Until recently, in the western part of the Southern Carpathians Triassic deposits were only known south of

the Nera River between Sasca Montană and Moldova Nouă, belonging to the Sasca-Gornjak structural unit (Săndulescu
1975). Core analysis of a borehole drilled NE of Oravi a (Brădi orul de Jos) led to the identification of a Triassic
formation of the same type and age (Early-Middle Triassic) about 20 km further northerly than previously known. As
in the Sasca Montană–Moldova Nouă area, the Triassic deposits are overlain by a Middle Jurassic sedimentary se-
quence, some tens of metres thick. The paper presents a biostratigraphical analysis of the foraminiferal assemblages
that have been identified in the drill core, gives a brief description of the microfacies of the carbonate deposits
encountered, and comments on the paleotectonic significance of the newly found Triassic occurrence.

Key words

: Triassic, Southern Carpathians, biostratigraphy, tectonics.

Introduction

The Triassic deposits cropping out between Sasca Montană
and Moldova Nouă (Fig. 1) in the western part of the South-
ern Carpathians were first mentioned by Böckh (1887). A re-
view of all the investigations dealing with the so-called ”Sas-
ca Triassic” is given in Strutinski et al. (1987). More
recently, two other papers were published on the subject by
Mirău ă & Gheorghian (1993) and Bucur et al. (1994). The
former presents paleontological proofs (conodont assemblag-
es) for the Ladinian age of, at least, part of the ”ceratite-bear-
ing black limestones” (Valea Cerbului Limestone Member in
Bucur et al. 1994).

The study of a borehole drilled NE of Oravi a, near the vil-

lage of Brădi orul de Jos (Figs. 1, 2), permitted the identifi-
cation of a Sasca-type Triassic in this sector as well. Maria
Paica provided preliminary petrographic data on the strato-
graphic succession encountered, Ioan I. Bucur performed the
biostratigraphic and microfacies analyses, and C. Strutinski
examined the implications on a regional scale of the Triassic
finding.

Biostratigraphical considerations

The stratigraphic sequence drilled by the 471 Brădi or

borehole is synthetically presented in Fig. 3. The upper 70
metres drilled consist of biopelmicrites, biointramicrites and
terrigeneous biomicrites. The biopelmicrites contain mollusc
(lamellibranch and gastropod) fragments, nodosariid and in-
volutinid forams and microoncoidal structures. Most fre-

Fig. 1.

The location of the Brădi orul de Jos borehole on the map

of Rumania and within the Re i a-Moldova Nouă zone. 1 — Pale-
ozoic deposits; 2 — Post-Triassic Mesozoic deposits; 3 — Trias-
sic deposits from Sasca-Moldova Nouă; 4 — location of the 471
Bradi or borehole.

40 BUCUR, STRUTINSKI and PAICA

quent among the foraminifers is Trocholina conica (Schlum-
berger) (Pl. II: Figs. 1–4), a species characteristic for the
Middle Jurassic (Bathonian) (Schlumberger 1898; Reichel
1955). Beneath this sequence, the well passed through car-
bonatic and terrigeneous deposits of Triassic age. A first as-
semblage including Glomospirella triphonensis Baud et al.
(Pl. III: Figs. 4, 5, 7–9), Nodosaria skyphica Efimova (Pl.
III: Fig. 18), Turriglomina mesotriasica Koehn-Zaninetti (Pl.
III: Figs. 16, 17) and rare dasyclads (?Oligoporella sp.) was
identified in the biomicrite of sample 4773.

Glomospirella triphonensis

, first described from the upper

Anisian of the Prealpes (Baud et al. 1971), was later found in
deposits corresponding largely to the Aegean–Anisian inter-
val (Brönnimann et al. 1972; Efimova 1974; Gazdzicki et al.
1975; Zaninetti 1976; Oravecz-Schefer 1987; Pirdeni 1988;
Trifonova 1992; Flügel et al. 1994).

Nodosaria skyphica

is cited from the Spathian–lower Ani-

sian of Bulgaria (Trifonova 1994), having, according to the
same author, a spread ranging from the Lower Triassic (Cau-
casus) to the lower Illyrian (Western Carpathians).

As to Turriglomina mesotriasica, it is a species well-

known in the Triassic of the entire Eurasian realm. In the
Western Carpathians it has been identified in upper Anisian-
lower Ladinian deposits (Salaj et al. 1983). In Hungary it
was mentioned in deposits assigned to the upper Anisian
(Oravecz-Schefer 1987), and Ladinian-Carnian, respectively
(Berczi-Makk 1985, 1993; Berczi-Makk et al. 1993). In Bul-
garia the same species has been described from deposits con-
sidered to belong to the Illyrian-basal Carnian (Trifonova
1987, 1993). Pirdeni (1987) mentions the species in the Ani-
sian from Albania. In Greece (Rettori et al. 1994) it was cited
in deposits assigned to the upper Bithynian–upper Ladinian,
and in Italy from the Anisian-Ladinian level (Premoli-Silva
1971; Limongi et al. 1987; Zaninetti et al. 1990). T. mesotri-
asica

has also been mentioned in the Ladinian of Turkey

(Dager 1978), in the Carnian of the Caucasus (Efimova
1974), as well as in middle Anisian deposits from China (He
Yan 1984; He Yan & Cai-Lian-quan 1991). According to Za-
ninetti (1976), the species is widespread in the Anisian–low-
er Ladinian of the whole Eurasian realm.

From the above it may be concluded that T. mesotriasica is

known from the Anisian up to the Carnian, being most often
cited within the upper Anisian–Ladinian interval. The depos-
its containing Turriglomina mesotriasica from the 471
Brădi orul borehole are comparable with those of the Valea
Cerbului Limestone Member from Sasca Montană, in which
T. mesotriasica

was likewise identified (Strutinski et al.

1987; Mirău ă & Gheorghian 1993; Bucur et al. 1994). Ac-
cording to conodont biostratigraphy (Mirău ă & Gheorghian
1993), the Valea Cerbului Limestone Member has an Illyrian
-early Ladinian age. Sample 4773, containing the above
specified assemblage, may most probably correspond to the
lower (upper Anisian) part of this member.

Another foraminifer assemblage has been identified in

sample 4783. It includes Ammodiscus multivolutus Reitlinger
(Pl. III: Fig. 15), Agathammina? iranica Zaninetti et al. (Pl.
III: Fig. 12), Trochammina almtalensis Koehn-Zaninetti (Pl.
III: Fig. 14), Trochammina jaunensis Brönnimann & Page;
Pilammina

cf. densa Pantič (Pl. III: Figs. 1–3, 6), Glomo-

spirella grandis

(Salaj) (Pl. II: Figs. 5–7, 9–12, 14, 16), Glo-

mospirella semiplana

Kochansky-Devidé & Pantič (Pl. II:

Fig. 8), Glomospira? cf. micas He & Yue (Pl. III: Fig. 13),
Endotriadella

cf. wirzi Koehn-Zaninetti and rare specimens

of Meandrospira pussila (Ho) (Pl. III: Fig. 10). The assem-
blage is quantitatively dominated by Glomospirella grandis
(Salaj). This species has been frequently cited from the Ani-
sian of the entire Eurasian realm: Koehn-Zaninetti (1969),
Bechstädt & Bradner (1970), Baud et al. (1971), Premoli-Sil-
va (1971), Brönnimann et al. (1973), Gazdzicki et al. (1975),
Zaninetti (1976), Dager (1978), Salaj et al. (1983), Berczi-
Makk (1985), Gaetani & Gorza (1989), Altiner & Kocygit
(1993), Rettori et al. (1994). It is most widespread in the
middle–upper Anisian.

Glomospirella semiplana

Kochansky-Devidé & Pantič

was mentioned from the same time interval (Baud et al.

Fig. 2.

Tectonic sketch of the Oravi a area (after Iancu, in Ilinca et

al. 1991, with permission). 1 — post tectonic cover (Quaternary-
Neogene); 2 — banatitic magmatic rocks (Paleogene-Upper Cre-
taceous); 3 — carbonate rocks (Mesozoic); 4 — metamorphic
rocks (Valea Cara ului series, Lower Paleozoic); 5, 5a — meta-
morphic rocks (Boc i a-Drimoxa series, Precambrian); 6 — terrig-
enous and carbonate rocks (Mesozoic-Permian); 7 — carbonate
rocks (Mesozoic: Jurassic-Lower Cretaceous); 8 — discontinuity
limit; 9 — normal limit; 10 — structural discordant limit; 11 —
fault line; 12 — reverse fault line (Oravita Fault); 13 — over-
thrusting plane; 14 — reverse syncline; 15 — reverse anticline;
16

— location of the borehole 471 Brădi or.

A NEW OCCURRENCE OF TRIASSIC DEPOSITS NE OF ORAVI A 41

1971; Efimova 1974; Gazdzicki et al. 1975; Salaj et al.
1983). According to Kristan-Tollmann & Tollmann (1983), it
may be synonymous with G. grandis.

Among the other species of the described assemblage, Pil-

ammina densa

, Trochammina almtalensis and Endotriadella

wirzi

are widespread in the Pelsonian–Illyrian of the Eur-

asian domain (Zaninetti 1976; Salaj et al. 1983; Senowbari-
Daryan et al. 1993; Bucur et al. 1994; Flügel et al. 1994).

Remarkable is the occurrence of rare specimens of Mean-

drospira pussila

(Ho), well-known in deposits ascribed to

the upper Scythian (Baud et al. 1974; Dager 1978; Berczi-
Makk 1986; Pirdeni 1988). Some specimens of the same spe-
cies were identified in Anisian deposits by Bechstädt &
Bradner (1970) (as M. iulia), Brönnimann et al. (1973), Za-
ninetti (1976), Trifonova (1993), Flügel et al. (1994).

As a whole, the assemblage of sample 4783 corresponds

most probably to the Pelsonian, i.e. to the Valea u ara
Limestone Member from Sasca Montană (Bucur et al. 1994).
Beneath it, the well passed through primarily terrigeneous
deposits with no fossil remains, which can be attributed, on
lithological grounds, to the Lower Triassic (Valea Vârâ i
Conglomerate Member of Sasca Montană, cf. Bucur et al.
1994). The sequence is disturbed by several faults (Fig. 3).

In the succession dolomitic rocks occur either within the

Anisian limestones (sample 4773, Pl. I: Fig. 11), or in associ-
ation with the terrigeneous rocks (sample 4799, Pl. I:
Fig. 12), without forming a distinct dolomitic member, as,
for instance, at Sasca Montană (Dealul Redut Dolomitic
Member, Bucur et al. 1994).

Microfacies and paleoenvironment

of the oncoid-bearing limestones

Two levels of oncoid-bearing rocks have been identified in

the 471 Brădi orul borehole. An upper level consists of bio-
clastic-oncoidic packstones with microoncoids, fragments of
molluscs, echinoderms, more rarely bryozoans and foramini-
fers (Pl. I: Figs. 1–2). These deposits have been assigned to
the Bathonian, due to the presence of Trocholina conica
(Schlumberger) (Pl. II: Figs. 1–4). Among foraminifers,
specimens of Lenticulina sp. and other nodosariaceans, as
well as rare textularians have been also noticed. The matrix
is micritic, with less than 1 % terrigeneous siltic material,
sometimes preserving bioturbation structures.

The microoncoids (Pl. I: Figs. 3–8) show dimensions of

1.24–1.70/2.20–3.10 mm and spheroidal-ovoidal shapes. The
core is most frequently represented by a bioclast (mollusc or
echinoderm fragment). The cores of some oncoids with a rel-
atively thin cortex are clasts of an older biomicritic, partially
consolidated, sediment.

The cortex, having a thickness of 0.10–0.34 mm, consists

of micritic laminae that cover the microoncoid body only on
certain sectors, thinning out towards the margins. Frequently,
the micrite is recrystallized to a fine-grained microsparite.
The micritic crusts incorporate small bioclasts and, more
rarely, small quartz crystals, being framed by ferruginous
films and sometimes by incrusting foraminifers of nubecu-
lariid type.

Oncoids with a micritic cortex have been described previ-

ously by Massari & Dieni (1983), Kuss (1988). These au-
thors mostly agree that this kind of oncoid forms in a carbon-
ate sedimentation environment of low energy, some tens of
metres deep.

Sample 4783 represents an oncoidic grainstone (Pl. I:

Figs. 9–10) belonging to a second level, that, on microfaunal
grounds (Fig. 3), has a middle Anisian age. The rock consists

Fig. 3.

Succession of the Mesozoic deposits bored by the 471 bore-

hole of Brădi orul de Jos. 1 — fenestral limestones; 2 — micritic
limestones; 3 — dolomites; 4 — oncoidic-bioclastic limestones; 5 —
micritic limestones with argillaceous laminae; 6 — shales and silt-
stones; 7 — sandstones; 8 — calcareous sandstones; 9 — breccia and
mylonites; 10 — vulcanic rocks (rhyolites); 11 — fault. V.S.L.M.
= Valea u ara Limestone Member; V.C.L.M. = Valea Cerbului
Limestone Member.

42 BUCUR, STRUTINSKI and PAICA

of a biopelsparitic groundmass that includes numerous fora-
minifers, fragments of lamellibranchs and echinoderms and
very rarely silty quartz grains (under 1 %). As a rule, the on-
coids have subcentimetric (0.4–0.5 cm) dimensions; some-
times, however, their length may reach 1.5 cm, depending on
the length of the lamellibranch fragment that generally forms
the core. The shape varies from spheroidal to irregular (most
frequently) and mimics the shape of the core. The lamelli-
branch fragments constituting the core are often perforated
marginally by endolithic cyanobacteria.

The cortex shows a thickness that varies between 0.05 and

2.50 mm. Sometimes, particularly if the cortex is very thin, it
develops only on one side of the core-building bioclast (Pl. I:
Fig. 10). The cortex has a girvanelloid-type structure, con-
sisting of tubes with 0.15–0.30 mm diameter (Pl. I: Figs. 14–
16). This structure is frequently destroyed by micritization.
Where the cortex is better developed it takes the form of a
cauliflower (Pl. I: Figs. 9, 13). Both the core and the growth
zones of the cortex are traced by ferruginous films.

Girvanella

oncoids have been described, among others, by

Peryt (1980, 1981), Biddle (1983), Kuss (1990). According
to Peryt (1980, 1981), oncoids with Girvanella may have dif-
ferent origins, but seemingly prefer quiet basins, character-
ized by tens of metres depths, as well as low sedimentation
and subsidence rates.

However, the oncoids from the 471 Brădi orul borehole

are much like those described by Čatalov (1983) as porostro-
matic oncoids in the Ladinian–Carnian from Bulgaria, and
particularly those within the oncobiosparite and oncointras-
parite levels, considered to be formed in a high energy medi-
um, where superficial oncoids (with a thin cortex) predominate.

Paleotectonic considerations

The presence of Triassic deposits in a borehole NE of

Oravi a must be considered in the context of previous inves-
tigations (e.g. Grubic 1967) which established: (1) the exist-
ence at the end of the Paleozoic and during the Mesozoic of
two distinct sedimentary basins in the area geographically
corresponding to the junction between the Carpathians and
the Balkans, and (2) the tectonic contact between them,
marked by the N-S oriented Oravi a Lineament (Strutinski
1987) which continues to the south, across the Danube River,
as the Ridanj-Krepoljin fault zone (Grubic 1967).

The main distinguishing feature of the western, more inter-

nal, basin was considered to be the presence of a Lower-
Middle Triassic formation which overlies a terrigeneous Up-
per Paleozoic (C

–P

) sequence, and is in turn unconform-

ably overlain by Middle Jurassic deposits (Boldur et al.
1964; Grubic 1967; Strutinski et al. 1987). In contrast, in the
eastern basin Triassic deposits were apparently missing,
while the Jurassic is generally represented by all its stages,
covering either Upper Paleozoic sediments, or directly the
metamorphic basement. The stratigraphic succession of the
western basin is considered to have been fully preserved only
south of the Danube, where it is well exposed in the environs
of Gornjak (Eastern Serbia). The eastern basin may comprise
the whole of the Re i a-Moldova Nouă zone north of the

Danube and the Golubac and Rtanj-Kučaj zones south of it,
thus representing the cover of the Getic domain.

Regarding the Oravi a fault system, there are at least three

different interpretations of it. According to Săndulescu
(1984), the Oravi a ”line” marks the front of the Locva
Nappe, considered to be the lowest sheet of the Supragetic
domain, thrusted from west to east over the Getic domain. In
this interpretation, the Triassic from Sasca Montană and
Moldova Nouă would belong to a third structural unit — the
Sasca-Gornjak stripped sheet (Săndulescu 1975) — wedged
between the Getic and Supragetic domains.

A different opinion is held by Iancu (Iancu 1986; Iancu in

Ilinca et al. 1991). According to her, the Oravi a fault does
not mark the front of a nappe, since it has a post-nappe, ad-
mittedly Miocene, age. Thus, it is considered that the Su-
pragetic nappes, including the Sasca-Gornjak stripped sheet,
were folded together after their emplacement and only after-
wards cut by the Oravi a fault, along which back-thrusting
took place (Fig. 2). This view is particularly based on the
fact that in the Oravi a region the homonymous fault dips
steeply (70

) to the east. Keeping this line of reasoning, Ian-

cu does not disagree with Săndulescu, that the Oravi a fault
actually represents the eastern limit of the Supragetic do-
main, but considers that this is only due to the fact that, in ac-
cordance with the back-thrusting model, an important uplift
of the Getic compartment took place, causing the complete
erosion of the Supragetic units east of the fault.

There is, however, a disagreement of what is actually un-

derstood as Oravi a fault or Oravi a ”line”. According to
Săndulescu (1975, 1984), this ”line” apparently lies to the
west of the Sasca-Gornjak ”wedge”, whereas in Iancu’s
view, it lies to the east (Fig. 2). In a previous paper (Strutins-
ki et al. 1987), we showed that the Oravi a ”line” is, in fact, a
branched system of faults, the Oravi a fault proper being the
most westerly of them, which borders the Triassic deposits to
the west. At the same time we favoured an interpretation op-
posed to the essentially constrictive tectonic models of the
above authors. Thus, in spite of sharing with Săndulescu
(1975, 1984) and Iancu (1986) the view that the depositional
site of the formations making up the Sasca-Gornjak Unit lay
in the western proximity of the Re i a-Moldova Nouă zone,
we did not consider the former to have been thrusted over the
latter, from W to E, but instead, to have migrated sublongitu-

Plate I: Figs. 1, 2

— Biomicrites with oncoids, mollusc and echin-

oderm fragments, scarsely bryozoans and foraminifers (Trocholi-
na

). 1 — sample 4770 (m.19), Bathonian,

6; 2 — sample 4769

(m.18.4), Bathonian,

6. Figs. 3–8 — Micritic oncoids. 3–7 —

sample 4769 (m.18.4), Bathonian,

60; 8 — sample 4770 (m.19),

Bathonian,

60. Figs. 9, 10 — Biodolosparites with Girvanella

oncoids and foraminifers. Sample 3783 (m.206), Valea u ara
Limestone Member (Pelsonian); 9 —

4; 10 —

6. Fig. 11 —

Biodolomicrites with scarsely mollusc fragments and foramini-
fers. Sample 4773 (m.90), Valea Cerbului Limestone Member (Il-
lyrian-lower Ladinian),

6. Fig. 12 — Laminitic dolomite. Sample

4799 (m.415), Valea Vârâ i Conglomerate Member (Lower Trias-
sic),

10. Figs. 13–16 — Structural details of Girvanella oncoids.

Sample 4783 (m.206), Valea u ara Limestone Member (Pelso-
nian); 13 —

15; 14–16 —

60.

A NEW OCCURRENCE OF TRIASSIC DEPOSITS NE OF ORAVI A 45

dinally along a sinistral transcurrent system, the Oravi a Lin-
eament. Structural arguments in favour of this view are di-
cussed elsewhere (Strutinski 1987) and refer to the linear
erosional outline of the lineament, the subhorizontal stria-
tions in fault planes regarded as movement vectors, the fre-
quency of ”exotic” fault erratics along various segments of
the system and the en-echelon trend of the folding in the
Re i a-Moldova Nouă zone with regard to the Oravi a Linea-
ment. This point of view is now supported by additional pa-
leogeographical and lithostratigraphic arguments.

First it should be stressed that the differences between the

two sedimentary realms as outlined by Grubic (1967) are by
no means important. On the contrary, Năstăseanu & Maksi-
movic (1983) emphasize the great similarity that exists be-
tween the sedimentary formations of the Getic and Sasca-
Gornjak units, respectively. This similarity may be observed
both at the Permian, and the Jurassic-Lower Cretaceous lev-
el. As concerns the Triassic formation of the Sasca-Gornjak
Unit, we showed (Strutinski et al. 1987) that the arenito-ru-
ditic complex (Valea Vârâ i Conglomerate Member, cf. Bu-
cur et al. 1994) reworked mainly medium-grade metamor-
phic rocks, including microclinic gneisses, widespread in the
Getic basement, in contrast to the underlying Permian con-
glomerates in which only low-grade metamorphics of the
Locva Series, occurring to the west, are reworked. These dif-
ferences strongly suggest that the area of provenance of the
debris accumulated in the Lower Triassic basin was situated
to the east, and not to the west, as during Permian times. This
may be interpreted in the sense that, whereas the Upper Pale-
ozoic basin extended much to the east, in accordance with
the areal distribution of the Permo-Carboniferous deposits
within the Getic domain (Fig. 1), the Triassic depocentre was
situated mainly to the west of the Oravi a Lineament, its
eastern confines extending only locally beyond it (Fig. 4a).
The Triassic from Brădi orul de Jos fits this interpretation, as
it probably belongs to the Re i a-Moldova Nouă zone, hence
to the cover of the Getic Unit. Paleogeographically, however,
it is obviously linked to the Triassic of the Sasca-Gornjak
Unit, mainly occurring south of the Danube, from which it
has supposedly been severed by a sinistral longitudinal trans-
port along the Oravi a Lineament. In this view, the Triassic
occurrences from Sasca Montană and Moldova Nouă (Fig. 1)
would represent tectonic slices marking the displacement
trail (Fig. 4b). Another element in support of our transcurren-
cy model is the absence of a Liassic formation in the north-
western part of the Re i a-Moldova Nouă zone, i.e. E and NE
of Oravi a. This means that the stratigraphic columns of the
Jurassic from this zone and from the Sasca-Gornjak Unit
south of the Danube (Năstăseanu & Maksimovic 1983) are

apparently the same. Accordingly, the two or three ”lenses”
of detrital formations that occur between Oravi a and Sasca
Montană along the Oravi a Lineament seem to represent dis-
lodged slices of the Valea Vârâ i Conglomerate Member of
Early Triassic age, rather than Lower Liassic deposits, as we
find them figured on the maps (Maier et al. 1973; Năstăseanu
et al. 1975). The first assumption is in good agreement with
our hypothesis, while the latter had to accept the exotic na-
ture of the slices, due to the absence of Liassic deposits in
the undisturbed stratigraphic succession of the neighbour-
hood (Getic Unit).

Plate II: Figs. 1–4

— Trocholina conica (Schlumberger). 1 —

sample 4769 (m.18.4), Bathonian,

120; 2–4 — sample 4770

(m.19), Bathonian,

60. Figs. 5–7, 9–12, 14, 16 — Glomospirella

grandis

(Salaj). Sample 4783 (m.206), Valea Susara Limestone

Member (Pelsonian); 5, 9–12, 14 —

120; 16 —

60. Figs. 13,

— Glomospirella sp. Sample 4773 (m.90), Valea Cerbului

Limestone Member (Illyrian-lower Ladinian),

120. Fig. 8 —

Glomospirella semiplana

Kochansky-Devidé & Pantič. Sample

4783 (m.2006), Valea u ara Limestone Member (Pelsonian),

60.

Fig. 4.

Fragmentation of the Triassic according to the transcurrency

hypothesis (not to scale). a — situation before the beginning of the ac-
tivity along the Oravi a Lineament; b — present situation. 1 — Oravi a
Lineament; 2 — margin of Triassic basin. O = Oravi a; S-M = Sasa
Montană-Moldova Nouă tract.

To conclude, the paleogeographic evolution in the area of

junction between the Carpathides and the Balkanides does
not favour the hypothesis of two distinct sedimentary realms
(Grubic 1967), but, instead, suggests tilting about horizontal,
most probably N-S directed, axes of the bottom of a single
sedimentary basin, that brought about the shifting of the dep-
ocentre axes alternatively more to the east (during Late Pale-
ozoic and probably Liassic times), or to the west (during the
Triassic). As a consequence, some stratigraphic terms (Trias-
sic, and Liassic, respectively) are generally confined to dis-
tinct parts of the basin, whereas others, of larger extent (e.g.
Permian) show the same features irrespective of their posi-
tion with regard to the Oravi a Lineament. It would be diffi-
cult to explain these aspects by assuming the existence of
two basins with an essentially different evolution. On the
other hand, even accepting the idea of a single sedimentary
basin, the E-W shortening hypothesis (e.g. Săndulescu,
1984), assumes a tectonic transport of the Sasca-Gornjak
Unit across the basin elongation and the facies zones, thus
requiring the juxtaposition, along the collision front (Oravi a
”line”) of rocks that, if similar in age, would be dissimilar
lithofacially. Such situations, which would support the thrust
hypothesis, have not been found, anyhow. Besides, the thrust
hypothesis is highly speculative, since most of the evidence for
it is thought to be buried under the Supragetic domain.

A NEW OCCURRENCE OF TRIASSIC DEPOSITS NE OF ORAVI A 47

The transcurrency model, is, by contrast, much more plau-

sible from present surface and subsurface data. Beyond
structural elements characteristic of strike-slip faulting, there
are also paleogeographical reasons in favour of it. Thus, the
similarity of facies on both sides of the Oravi a Lineament
points to the fact that the transcurrent movement took place
subparallel to the basin elongation and the facies zones. Be-
sides, the distance between the most northerly occurrences of
Triassic formations south of the Danube (Gornjak zone) and
the Triassic reported herein in the subsurface NE of Oravi a
(approx. 70–80 km), may be an indication of the amount of
displacement along the Oravi a Lineament. As regards the
age of the lineament, it must be pre-Upper Cretaceous as it
obviously served as a conduit for the Upper Cretaceous mag-
matites (”banatites”) that are confined to the fault zone.

Gornjak Unit to the west. Therefore, the paleogeographical
evolution in the zone of junction between the Carpathides
and Balkanides, points to a single sedimentary basin that
was, already in the course of its evolution or afterwards, dis-
placed sublongitudinally by the Oravi a Lineament, regarded
as an important transcurrent system. In this view, the Oravi a
Triassic represents the till now missing counterpart of the
Triassic from Eastern Serbia, displaced from it counterclock-
wise by about 70–80 km. Along the displacement trail the
Triassic deposits appear as dislodged slices, e.g. at Sasca
Montană and Moldova Nouă. In spite of local overthrusts in
the vicinity of the Oravi a Lineament, the main features of
the contact between the Getic and the Sasca-Gornjak units
indicate that it is primarily a strike-slip structure.

Acknowledgements:

Part of this paper was prepared by one

of us (I.I.B.) during a Humboldt fellowship at the Institut für
Paläontologie, Erlangen. He expresses his gratitude to the
Humboldt Foundation (Bonn) and to Prof. E. Flügel (Erlan-
gen). The paper is part of the research theme B41 granted by the
Ministry of Education through CNCSU Grant 58. Thanks are
also due to Marina Strutinski and Janeta Pop for their help with
the drawings.

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