GEOLOGICA CARPATHICA, 53, 4, BRATISLAVA, AUGUST 2002
245—256
RELICS OF THE MELIATA OCEAN CRUST: GEODYNAMIC
IMPLICATIONS OF MINERALOGICAL, PETROLOGICAL
AND GEOCHEMICAL PROXIES
PETER IVAN
Department of Geochemistry, Faculty of Science, Comenius University, Mlynská dolina G, 842 15 Bratislava, Slovak Republic;
ivan@fns.uniba.sk
(Manuscript received October 12, 2000; accepted in revised form December 13, 2001)
Abstract: Relics of the oceanic crust of the Triassic-Jurassic Meliata Ocean are preserved as dismembered incomplete
ophiolite sequences only in several small lithostratigraphic units mostly in the Inner Western Carpathians. The current
data on these remnants with special emphasis on volcanic rocks are summarized in the present paper. Mafic volcanic
rocks representing relics of the Meliata oceanic crust differ from each other by the following characteristics: (1) preser-
vation of magmatic textures and structures, (2) geochemical type, (3) metamorphic evolution, (4) related sedimentary
rocks and (5) recent tectonic position. On the basis of these differences, three groups of metabasalts related to the former
oceanic floor can be discerned: (1) HP/LT metamorphosed basalts and dolerites with scarce gabbro as slices and small
blocks in the Bôrka Nappe, (2) mostly LP/LT metamorphosed basalts and dolerites occurring as olistoliths in mélange in
the Jaklovce, Meliata, Bódva Valley Ophiolite and Darnó Hill Formations, and (3) recycled, almost complete ophiolite
magmatic rocks forming clasts in the Upper Cretaceous Gosau-type conglomerate from Dobšinská adová Jaskyňa
village. The distribution of relatively immobile trace elements (REE, HFSE) in metabasalts indicates their formation in
the back-arc setting. In the initial stage of opening of the Meliata Ocean, the arc-like and back-arc basin basalts, erupted
in the environment of carbonate or pelitic sediments, were generated. The evolved stage is characterized by generation of
basalts close to the N-MORB type in association with abyssal sediments. Basalts close to E-MORB are assumed to be a
melting product of an enriched mantle source probably locally present beneath the spreading basin. Closure of this ocean
in the Middle Jurassic time was related to the subduction and formation of the accretionary prism. Mostly the relics of the
marginal parts of the former oceanic basin were subducted and consequently exhumed, whereas the relics of central parts
were preserved in the accretionary prism. The original location of the Meliata Ocean suture is not known. The present-
day tectonic position of the oceanic crust relics in the Inner Western Carpathians is extremely complex as a consequence
of the repeated nappe forming activity, erosion and plate kinematics. It seems likely that these relics represent a western
continuation of the Hellenide-Dinaride ophiolites displaced by microplate motions in the Miocene.
Key words: Western Carpathians, Meliata Ocean, geodynamics, back-arc basin, oceanic crust.
Introduction
The opening and closing of the Meliata Ocean were important
events, which substantially influenced the Mesozoic geologi-
cal history of the Inner Western Carpathians. In spite of the
fact that the Meliata Ocean is a frequently used term in many
geodynamic, tectonic and petrological models and schemes,
there are restricted data only related to the origin and structure
of this former ocean. Such a situation is caused by the bad
preservation of relics of the Meliata Ocean basin floor and its
marginal sedimentary filling which form innumeral slices or
olistoliths only. The aim of this paper is to summarize our cur-
rent knowledge concerning real oceanic crust relics of the Me-
liata Ocean in the Western Carpathians realm as follows from
the interpretation of mineralogical, petrological and geochemi-
cal data.
The Meliata Ocean – definition
The Meliata Ocean (or Meliata-Hallstatt Ocean) is the des-
ignation of a hypothetical oceanic basin in the Tethyan Realm,
whose spreading was in progress during the Middle Triassic
and closure in the Middle to Upper Jurassic time (Kozur 1991;
Channell & Kozur 1997). It was deduced mostly from results
of lithological and petrological investigations, which discov-
ered abyssal sediments and various mélange types first in the
Mesozoic units of the Inner Western Carpathians and then also
in the Juvavic nappes of the Northern Calcareous Alps. The
Meliata Ocean is regarded as a northwestern ending of the
Tethys Ocean (Kovács 1997; Neugebauer et al. 2001), a basin
connected with this ocean or an isolated active marginal basin
(Stampfli 1996, 2000).
Regional distribution of the Meliata Ocean relics
in the Alpine-Carpathian-Pannonian realm
Relics of the Meliata Ocean have been found as isolated oc-
currences along the northern and southern borders of the litho-
spheric block referred to as ALCAPA (Alpine-Carpathian-
Pannonian), which included mainly the area of the Eastern
Alps and Western Carpathians (Fig. 1). The prevailing part of
relics of the Meliata Ocean near the northern border of ALCA-
PA block is located in the Northern Calcareous Alps. They are
represented by Jurassic breccias and sedimentary mélanges
246 IVAN
containing redeposited marginal facies of the Meliata Ocean
(Gawlick et al. 1999). Relics of the real oceanic crust are re-
stricted to small bodies of metabasalts with the oceanic affini-
ty in the Scythian shales (Kralik et al. 1984). In the Western
Carpathians such relics are known in the form of recycled sed-
imentary material (clasts) in the Cretaceous conglomerates in
the Klape Unit (Pieniny Klippen Belt; Ivan & Sýkora 1997).
Near the southern border of the ALCAPA block the occurrenc-
es of oceanic crust relics of the Meliata Ocean have been
found in the Medvednica Mts near Zagreb (Halamić et al.
1998, 1999), in the boreholes Inke-9 and Tóalmás-2 and -3 in
the Pannonian Lowland (Harangi et al. 1996) and in the Inner
Western Carpathians where the majority of such occurrences
known at present are concentrated. In the last mentioned area
most of the oceanic crust relics are located in its northern part
where they occur in the Meliata Formation (Hovorka & Spi-
šiak 1988, 1998), in the Bôrka Nappe (Ivan & Kronome 1996;
Mazzoli & Vozárová 1998) and also in the Cretaceous con-
glomerates near Dobšinská adová Jaskyňa (Hovorka et al.
1990; Fig. 2). In the southern part of the Inner Western Car-
pathians they were found in the Bódva Valley Ophiolite For-
mation and Darnó Hill Formation (Harangi et al. 1996).
Oceanic crust relics of the Meliata Ocean in the
Inner Western Carpathians – a concise outline
A wide variability of such parameters as: (1) preserved mag-
matic structures and textures, (2) geochemical type of mag-
matic rocks, (3) metamorphic evolution, (4) related sedimenta-
ry rocks and (5) recent tectonic position, is typical for
individual occurrences of the oceanic crust relics of the Melia-
ta Ocean. Taking these differences into account, all the lithos-
tratigraphic units containing oceanic crust relics of the Meliata
Ocean can be divided into four groups: (1) units which experi-
enced HP/LT metamorphism as a whole (units of the Bôrka
Nappe), (2) units with LP/LT metamorphosed oceanic rocks
only (Jaklovce Formation recently referred to the Meliata For-
mation, Meliata Formation s.s. and Darnó Hill Formation), (3)
evaporitic mélange with low-grade metamorphosed oceanic
rock fragments with rare indications of HP/LT event (Bódva
Valley Ophiolite Formation) and (4) units with recycled oce-
anic crust material (Dobšinská adová Jaskyňa conglomerate).
A review of the lithology of these units and petrography of
their oceanic rocks is summarized in Table 1.
The presence of basalts/metabasalts as the prevailing igne-
ous rock types in all the mentioned groups allows a reliable
testing of the oceanic geodynamic setting of their generation
using trace element distribution or composition of preserved
magmatic clinopyroxenes. The composition of selected relic
magmatic clinopyroxenes is illustrated in Table 2, selected
major and trace element analyses of the basaltic rocks repre-
sented in the Meliata Ocean crust relics from different lithos-
tratigraphic units are summarized in Table 3.
Bôrka Nappe
The newly defined Bôrka Nappe (Mello et al. 1998) located
in the northern part of the Slovenský kras Mts and in the west-
A. Lithostratigraphy of the Inner Western Carpathians
GEMERIC UNIT (Gemericum)
Early Paleozoic
Formations
Štós Formation (Fm.), Gelnica Group (Gr.), Smrečinka
Fm., Rakovec Fm., Klátov Fm.
Late Paleozoic
Formations
Gočaltovo Gr., Rudňany Fm., Zlatník Fm., Hámor Fm.,
Krompachy Gr., Ochtiná Fm., Črmeľ Fm.
MELIATIC UNIT (Meliaticum)
Bôrka Nappe
Formations
Hačava Fm., Kobeliarovo Fm., Nižná Slaná Fm., Jasov
Fm., Bučina Fm., Rudník Fm.
Meliata
Supergroup
Jaklovce Fm., Meliata Fm. (s.s.), Bódva Valley Ophiolite
Fm., Darnó Fm.
TORNAIC UNIT (Tornaikum)
SILICIC UNIT (Silicicum)
GOSAU GROUP
Note: More detailed data to the individual units can be found in following
papers and references herein: Gemeric Unit — Ivan (1996; 1997); Meliatic Unit
— Mock et al. (1998), Mello et al. (1998), Ivan & Mello (2001); Tornaic Unit
— Mello et al. (1997), Kozur & Mock (1997); Silicic Unit — Mello et al.
(1997), Kozur & Mock (1997), Less (2000); Gosau Group — Mello et al.
(2000).
B. Oceanic crust relics of the Meliata Ocean in the lithostratigraphic formations of
the Meliatic Unit
FORMATION OCEANIC
CRUST RELICS
GEOLOGY GEO-
CHEMICAL
TYPES OF
BASALTS
METAMORPHIC
ALTERATION
Hačava Fm.
(Bôrka Nappe)
Basalts, dolerites,
peridotites, cherts,
(i-gabbro),
Olistoliths in
tectonized
olistostroma,
tectonic slices
→
IAT
BABB
→
N-MORB
(ORTM), (LP/LT),
HP/LT (whole
formation)
Kobeliarovo
Fm.
(Bôrka Nappe)
Fe-dolerites,
basalts, peridotites,
cherts
Olistoliths in
tectonized
olistostroma
IAT
BABB
(HP/LT)
→
LP/LT-GS
Jaklovce Fm.
Basalts, peridotites,
cherts
Olistoliths, in
olistostroma,
tectonic slices
BABB
→
N-MORB
LP/LT-GS
Meliata Fm.
(s.s.)
Basalts, peridotites,
cherts
Olistoliths in
olistostroma
BABB
→
N-MORB
LP/LT-GS
Bódva
Valley
Ophiolite Fm.
Peridotites,
gabbrodolerites,
Fe-gabbrodolerites,
dolerites, basalts,
cherts
Olistoliths in a
salinary
mélange
E-MORB
N-MORB
LP/LT-GS
(ORTM)
(HP/LT)
→
LP/LT-GS
Darnó Fm.
Basalts, dolerites,
gabbrodolerites,
cherts
Olistoliths in
olistostroma
BABB
E-MORB
LP/LT-GS
Gosau Group
Peridotites,
i-gabbros, basalts,
dolerites, cherts,
c-gabbros,
pyroxenites
Pebbles in
conglomerate
BABB
→N-MORB
ORTM
LP/LT-PP,PA,GS
HP/LT
Explanations: i-gabbros — isotropic gabbros, c-gabbros — cumulate gabbros, (gabbro)
— scattered finding only, IAT— island arc tholeiite, BABB — back arc basin basalt, N-
MORB — normal mid-ocean ridge basalt, E-MORB — enriched mid-ocean ridge basalt,
ORTM — oceanic ridge-type metamorphism, HP/LT — high pressure/low temperature
metamorphism (epidote-blueschist facies), LP/LT — low pressure/low temperature
metamorphism, PP — prehnite-pumpellyite facies, PA — prehnite-actinolite facies, GS
— greenschist facies, (ORTM) — indication of older ORTM-phase.
Table 1: Lithostratigraphical division of the Inner Western Car-
pathians and an overview of the formations with oceanic crust rel-
ics of the Meliata Ocean (see also Fig. 2).
RELICS OF THE MELIATA OCEAN CRUST: GEODYNAMIC IMPLICATIONS 247
Table 2: Representative analyses of various magmatic clinopyroxenes from the metamorphosed oceanic basalts of the Meliata Ocean.
Low aluminium and titanium clinopyroxene types are related to the early stage of basalt crystallization.
1
2
3
4
5
6
7
8
9
10
Sample
VVS16
VVS16
VVS16
VVS16
FJAK40
FJAK40
FJAK40
BRU1/b
BRU1/b
BRU1/b
SiO
2
54.12
54.31
52.90
50.75
52.60
49.28
47.88
53.28
50.42
49.59
TiO
2
0.36
0.54
0.78
1.00
0.39
1.51
2.03
0.62
1.13
1.56
Al
2
O
3
1.90
1.62
3.59
3.54
1.59
3.90
3.45
1.60
4.06
3.12
FeO
5.72
8.83
5.98
7.67
10.05
10.15
15.35
9.14
7.71
14.09
MnO
0.22
0.29
0.13
0.09
0.00
0.00
0.39
0.31
0.30
0.32
MgO
17.78
17.14
16.66
15.86
19.59
14.39
11.88
17.47
15.36
12.38
CaO
19.67
17.83
20.18
21.48
15.22
19.77
18.17
17.51
20.17
18.44
Na
2
O
0.28
0.34
0.33
0.46
0.30
0.34
0.30
0.21
0.31
0.38
Cr
2
O
3
0.12
0.11
0.12
Total
100.06
100.90
100.66
100.96
99.74
99.35
99.45
100.39
99.59
99.88
6 O
Si
1.968
1.976
1.920
1.868
1.939
1.858
1.847
1.954
1.875
1.887
AlIV
0.032
0.024
0.080
0.132
0.061
0.142
0.153
0.046
0.125
0.113
AlVI
0.049
0.045
0.073
0.022
0.008
0.031
0.004
0.023
0.052
0.027
Ti
0.010
0.015
0.021
0.028
0.011
0.043
0.059
0.017
0.032
0.045
Fe
0.174
0.269
0.182
0.236
0.310
0.320
0.495
0.280
0.240
0.449
Mn
0.007
0.009
0.004
0.003
0.000
0.000
0.013
0.010
0.010
0.010
Mg
0.964
0.929
0.901
0.870
1.076
0.809
0.683
0.970
0.851
0.702
Ca
0.766
0.695
0.785
0.847
0.601
0.798
0.751
0.688
0.803
0.752
Na
0.020
0.024
0.023
0.033
0.022
0.025
0.023
0.015
0.022
0.028
Cr
0.003
0.003
0.004
Note: VVS16 — HP/LT metamorphosed basalt of BABB type, Bôrka Nappe, Hačava Fm., loc. Radzim Mt.; FJAK40 — LP/LT metamorphosed basalt
close to N-MORB type, Jaklovce Fm., loc. Margecany, quarry near lime factory; BRU-1a — LP/LT metamorphosed basalt close to N-MORB type,
Meliata Fm., loc. Brusník village, borehole BRU-1, 781.5 m. Data sources: Vozárová & Vozár (1992) — BRU-1 and original data. Electron
microprobe analyses of clinopyroxenes were carried out at Slovak Geol. Survey on a Jeol 733 microprobe using the following conditions and standards:
15 kV, 2×10
–8
A, ZAFO; Na, Al — albite, Ca — wollastonite, Mg — MgO, Mn — willemite, Fe,Cr — chromite and Ti — TiO
2
.
Table 3: Representative analyses of major and selected trace elements in the metamorphosed basalts forming the oceanic crust relics of
the Meliata Ocean.
1
2
3
4
5
6
7
8
9
Sample
FBO-12
VVS-16
VHA-3
Jakl. (12)
Tk-2/254
VM-10
Szo-4
Dar-4
Rm-135
SiO
2
48.03
48.64
47.63
49.00
48.11
49.37
44.81
47.52
TiO
2
3.23
1.62
1.95
1.37
1.15
1.63
3.69
1.82
Al
2
O
3
13.00
15.03
14.94
15.50
16.11
14.97
13.41
14.88
Fe
2
O
3
7.61
3.73
5.33
2.28
11.08*
5.20
7.54
10.96*
FeO
6.38
6.39
6.86
6.35
-
5.14
6.61
-
MnO
0.17
0.17
0.17
0.17
0.25
0.25
0.14
0.17
MgO
5.06
6.69
6.46
7.05
7.41
5.07
6.12
7.51
CaO
8.66
10.37
9.12
8.90
5.56
6.03
11.11
9.97
Na
2
O
3.13
3.64
3.30
4.15
5.11
6.94
3.02
3.30
K
2
O
1.23
0.02
0.27
0.54
0.33
0.03
0.50
0.59
P
2
O
5
0.04
0.17
0.17
0.18
0.12
0.29
0.32
0.21
LOI
2.14
1.92
2.16
3.10
4.57
5.15
4.23
3.10
Total
99.32
99.03
99.05
99.34
99.80
100.58
102.16
100.03
Cr
28.6
191
455
98.0
413
270
210
329
310
Ni
145
156
81
92
112
Co
25.9
45.5
50.5
122
39
30.5
37
39
Sc
36.0
46.0
44.5
79.0
29.2
31
45
38
V
467
280
313
330
230
233
394
348
346
La
11.5
3.9
5.3
4.2
1.3
2.8
11.1
6.54
6.8
Ce
33.0
14.3
15.5
16.7
5.0
9.3
28.5
16.94
19.0
Nd
28.3
13.2
11.2
13.2
8.4
12.89
9.0
Sm
8.9
4.2
4.2
4.1
3.1
5.63
3.99
4.40
Eu
2.65
1.45
1.45
1.60
0.86
1.10
1.95
1.38
1.42
Tb
1.70
0.79
0.98
1.40
0.61
0.90
Yb
6.3
3.0
3.7
5.00
2.27
2.50
3.51
3.64
3.0
Lu
1.05
0.38
0.63
0.92
0.31
0.41
0.48
0.42
Hf
6.1
2.65
3.2
3.3
1.8
3.6
4.8
3.2
Ta
0.40
0.117
0.199
1.1
0.73
0.6
0.3
Th
2.05
0.58
1.10
0.7
0.6
0.6
Nb
6
1
2
1
11
10
8.7
1
Y
58
30
35
24
22
46
38.2
29
Zr
212
102
112
48
141
249
129
129
Ba
92
43
24
63
55
16
43
80
128
Note: Fe
2
O
3
* — total Fe like Fe
2
O
3
. 1–3 — Bôrka Nappe: 1 — HP/LT metamorphosed fractionated arc-like basalt, loc. Bôrka village; 2 — HP/LT metamorphosed
basalt of BABB type, loc. Radzim Mt, 3 — HP/LT metamorphosed dolerite close to N-MORB type, loc. Hačava, ca. 1 km NW of village, 4 — Jaklovce Fm.,
LP/LT metamorphosed basalt close to N-MORB type, loc. Jaklovce village; 5 — Bódva Valley Ophiolite Fm., LP/LT metamorphosed dolerite close to N-MORB
type, loc. Tornakápolna, borehole Tk-2, 254 m, 6 — LP/LT metamorphosed basalt of E-MORB type, loc. Tornakápolna, borehole Tk-3, 493.8-494.2 m; 7 —
LP/LT metamorphosed coarse-grain dolerite of E-MORB type, loc. Szögliget, borehole Szo-4, 209 m; 8 — Darnó Hill Fm., LP/LT metamorphosed dolerite of
transitional type between E- and N-MORB; 9 — Darnó Hill Fm., LP/LT metamorphosed coarse-grain dolerite close to BABB type, loc. Darnó Hill, borehole RM-
135, 434 m. Data sources: Downes et al. (1990) -8, Hovorka & Spišiak (1993) -4, Harangi et al. (1996) -5,7 and 9, Horváth (2000) -7 (major elements) and original
data. Analyses of REE, Cr, Co, Sc, Hf, Ta and Th in all samples were performed by the INAA (original analyses in laboratories of the company MEGA, Stráž pod
Ralskem, Czech Republic); original analyses of other elements were carried out in Ecologic Laboratories Inc., Spišská Nová Ves, Slovak Republic using ICP OES
method.
248 IVAN
ern part of the Spišsko-gemerské rudohorie Mts (Fig. 2), is
composed of several partial nappes or slices formed by differ-
ent lithostratigraphic formations all metamorphosed in HP/LT
conditions. Two of them, preliminarily referred to as the Hača-
va and Kobeliarovo Formations, differing from each other by
the metamorphic P—T conditions, contain oceanic crust relics
of the Meliata Ocean, the others comprise rocks of non-ocean-
ic origin only.
Oceanic crust relics in the Hačava Formation, formed by
tectonic slices and olistoliths of metabasalts, metadolerites and
rarely also metagabbros, underwent progressive metamorphic
evolution from prehnite-pumpellyite through greenschist to
epidote blueschist facies conditions. Vestiges of the former
ocean-ridge type metamorphism have been found in the doler-
ites and gabbros (Ivan, in press). The original magmatic min-
eral associations were replaced by the association composed
of Na-amphibole (glaucophane) and epidote with variable
amounts of Na-pyroxene (acmite), clinozoisite, albite, titanite,
white mica and garnet (Faryad 1995a; Mazzoli & Vozárová
1998). Relics of magmatic clinopyroxene and amphibole of
former metamorphic stages have been found locally. Clinopy-
roxene composition (Fig. 3) fully conforms to the geochemical
type of basalt (BABB type mentioned below). In spite of
metamorphic recrystallization the magmatic textures are still
recognizable and hyaloclastic, variolitic, intersertal, ophitic,
doleritic and gabbroic textures have been identified together
with the former glassy chilled margins (Ivan, in press). Such a
variability of magmatic textures in metabasalts indicates that
basalts originally formed lava flows with glassy or lava brec-
cia rinds and probably also pillow lavas.
The study of the distribution of REE and other relatively im-
mobile trace elements revealed that the geochemical types of
metabasalts vary from typical oceanic N-MORB (normal mid-
ocean ridge basalt) type through transitional BABB (back-arc
basin basalt), both with flat primitive REE patterns (Fig. 4) to
arc-related types with distinct deficit of the SZC (subduction
zone component – e.g. Ta – Fig. 6) and LREE enrichment
(Ivan & Kronome 1996). Arc types of metabasalt were erupted
in a carbonaceous environment (now transformed to marbles)
whereas BABB types seem to be related to metamorphosed
pelitic rocks and a type close to N-MORB is even accompa-
nied by dark metamorphosed radiolarite.
The Kobeliarovo Formation lithologically resembles the
Hačava Formation. Oceanic crust relics occur in association
with metamorphosed carbonates (marbles) forming olistoliths
in the metapelitic (phyllitic) matrix. They are represented by
dolerites and smaller amounts of basalts with still preserved
dolerititic or ophitic textures, which are geochemically close
to fractionated arc-related basalts. Hyaloclastites, intensively
altered and recrystallized together with the surrounding car-
bonate rocks, have also been found. Magmatic rocks in the
Kobeliarovo Formation were originally metamorphosed in
epidote blueschist metamorphic conditions and later retro-
gressed to greenschist conditions. Actinolite, chlorite, albite,
octahedron-forming magnetite and titanite compose the most
common mineral assemblage.
The age of oceanic crust relics is not exactly known in the
Bôrka Nappe, it is supposed to be Triassic. The age of HP/LT
metamorphic stage was dated by the
40
Ar/
39
Ar method on
fengite to 150—160 Ma (Maluski et al. 1993; Dallmeyer et al.
Fig. 1. Localization of the Meliata Ocean remnants in the Alpine-Carpathian-Pannonian area. Explanations: circles – oceanic crust rel-
ics (olistoliths), triangles – recycled relics of the oceanic crust relics as pebbles in the Cretaceous conglomerates, squares – relics of
marginal facies of the MHO resedimented into Jurassic basins in the Northern Calcareous Alps. Structural units were taken from the pa-
per by Harangi et al. (1996).
RELICS OF THE MELIATA OCEAN CRUST: GEODYNAMIC IMPLICATIONS 249
1996; Faryad & Henjes Kunst 1997) and its peak P—T condi-
tions as 12 kbar at 400—460
°C (Faryad 1995a, 1997).
Jaklovce Formation
The Jaklovce Formation is situated in the eastern part of the
North Gemeric Zone, which is an area of peculiar geological
structure on the northern border of the Inner Western Car-
pathians (Fig. 2). According to Mock et al. (1998) it is formed
by mélange with claystone, siliceous shales, argillites and
sandstone matrix and olistoliths of pale shallow-water lime-
stones (Honce limestones), pelagic cherty limestones, dolo-
mites, radiolarites and clastic sediments. Pale-green kerato-
phyre and massive pink rhyolite olistoliths have been found as
well. An important component of the mélange are also olis-
toliths or tectonic slices of basalts usually spatially related to
red radiolarites or red abyssal pelitic sediments (Kamenický
1957; Hovorka & Spišiak 1988, 1993, 1997). The Jaklovce
Formation has recently come to be regarded as a part of the
Meliata Formation.
Magmatic textures and partly also primary mineral composi-
tion of basalts are well preserved. Observed glassy, intersertal,
variolitic, glomeroophitic and ophitic textures (Kamenický
1957) reflect variations in the cooling rate of the basaltic melt.
Lava breccias indicate direct contact with water. Basalts erupted
probably in the form of sheet lava flows; pillow lavas have not
been reliably proved. The primary mineral association compris-
es clinopyroxene, plagioclase and small amounts of olivine and
ilmenite. Low-grade metamorphic alteration (in greenschist fa-
cies conditions) mostly affected the vicinity of tectonic fissures
causing saussuritization and local albitization of plagioclase,
chloritization of olivine and partly also of clinopyroxene and
formation of small chlorite-epidote-albite-pyrite veins.
Magmatic clinopyroxene composition (Fig. 3) as well as the
distribution of REE and other relevant trace elements indicate
that the basalts of the Jaklovce Formation are close to N-
MORB having typical flat chondrite normalized REE patterns
with characteristic LREE depletion (Fig. 4). Nevertheless, the
still identifiable effect of the subduction zone component
(SZC) in the mantle source on the composition of the basalts
Fig. 2. Geological sketch-map of the Inner Western Carpathians. Oceanic crust relics of the Meliata Ocean have been found in the Bôrka
Nappe, Meliata Formation (displayed together with Jaklovce Formation located NE of the town of Gelnica), Bódva Valley Ophiolite For-
mation (in boreholes only) and in the Darnó Formation (off the displayed area). Cretaceous Gosau-type conglomerates contain recycled
material of the Meliata Ocean crust. Early and Late Paleozoic formations belong to the Gemeric Superunit, Mesozoic carbonate forma-
tions to the Silicic Unit partly also to the Turnaic Unit.
RELICS OF THE MELIATA OCEAN CRUST: GEODYNAMIC IMPLICATIONS
250 IVAN
(deficit of Ta together with Th enrichment) is important evi-
dence for generation in the back-arc setting (Fig. 6). Some the
basalt samples of this formation crystallized from fractionated
magmas as follows from the elevated total REE content and
positive Eu anomaly, both a potential consequence of cumu-
late gabbro formation in the rift zone.
The age of oceanic crust relics in the Jaklovce Formation,
that is basalts and related red radiolarites and radiolarian
Fig. 3. TiO
2
-SiO
2
/100-Na
2
O discriminate diagram (Beccaluva et
al. 1989) for relic magmatic clinopyroxenes from ophiolitic ba-
salts representing former oceanic crust of the Meliata Ocean.
More “arc-like” character of the metabasalts from Radzim Mt
(Bôrka Nappe) seems to be evident. Explanations: 1 – Jaklovce
area (Jaklovce Formation), 2 – Radzim Mt (Bôrka Nappe), 3 –
BRU-1 borehole (Meliata Formation), E-MORB – enriched mid-
ocean ridge basalts, N-MORB – normal mid-ocean ridge basalts,
WOPB – within oceanic plate basalts, IAT – island arc tholei-
ites, FABA – intra-oceanic fore-arc basaltic andesites and andes-
ites, BON – boninites. Data sources: Hovorka & Spišiak 1988;
Vozárová & Vozár 1992 and unpublished data.
schists, was determinated paleontologically as Triassic (Ladin-
ian; Kozur & Mock 1985) whereas the age of mélange form-
ing is Middle Jurassic (Bathonian?; Kozur & Mock 1995).
Meliata Formation
The Meliata Formation is exposed on the surface in several
small outcrops – tectonic windows – in the northern part of
the Slovenský kras Mts to the south of an important fault zone
– the Rožňava Line (Fig. 2). Under the surface the Meliata
Formation forms footwall of the carbonate Silica Nappe and it
has been recorded in several boreholes (Vozárová & Vozár
1992). The lithology of this unit is similar to the previously
mentioned Jaklovce Formation (and partly also to the Bódva
Valley Ophiolite Formation), which is the reason for their clas-
sification as a single unit by some authors (e.g. Mello et al.
1997). The Meliata Formation, like the Jaklovce Formation, is
a mélange with mostly carbonate olistoliths (or tectonic slices)
in a matrix composed of deep-water shales with sparse thin in-
tercalations of breccias, sandstones and thin-bedded radiolar-
ites (Mock et al. 1998). Rhyolite olistoliths have also been
found together with oceanic crust relics represented by small
bodies of red radiolarites, fully serpentinized spinel peridotites
and metabasalts. Effusive types often with volcanic glass as a
substantial component originally dominated among the me-
tabasalts. The primary textures such as brecciate, intersertal or
variolitic are still recognizable (Kantor 1955) in spite of the in-
tensive metamorphic alteration to greenschists composed of
albite, chlorite, carbonate and a smaller amount of ilmenite
and titanite. A unique occurrence of the basalt with glassy to
variolitic texture with preserved magmatic clinopyroxene
crystallized in direct contact with black chert has been also
found.
Limited geochemical data indicate close similarity to N-
MORB type for metabasalts from the Meliata Formation
(Figs. 4, 6).
The Triassic age (Ladinian) of the oceanic crust relics in the
Meliata Formation is derived from the paleontologically prov-
en age of red radiolarites (Dumitrica & Mello 1982). The mé-
lange was formed in Jurassic time (Upper Callovian to Lower
Oxfordian or Middle Bathonian to Lower Callovian) as fol-
lows from paleontologically dated radiolarites from the matrix
(Kozur et al. 1996; Mock et al. 1998).
Bódva Valley Ophiolite Formation (BVOF)
BVOF has been found in the boreholes only in the Bódva
valley SE of the Slovenský kras/Aggtelek Mts (northern Hun-
gary). It is represented by slices or small fragments of ophi-
olitic rocks (from dm to 100 m in scale) embedded into ductile
Upper Permian evaporitic rocks (Réti 1985; Harangi et al.
1996; Horváth 1997). The formation comprises serpentinized
spinel peridotites and metamorphosed gabbrodolerites, ferro-
gabbrodolerites and basalts. Variable textures – variolitic, hy-
alopilitic, intersertal to ophitic – are typical for the basalts.
According to Harangi et al. (1996) the majority of the basalts
were originally pillow lavas and lava breccias formed as prod-
ucts of submarine eruptions. Magmatic rocks of the BVOF un-
derwent multi-stage metamorphic alteration resulting in trans-
Fig. 4. Chondrite normalized REE patterns for metabasalts and
metadolerites representing Meliata Ocean relics in the northern
part of the Inner Western Carpathians. Note primitive flat shape of
patterns typical for oceanic rocks. Explanations: 1 – Jaklovce
Formation, 2 – Meliata Formation, 3 – Bôrka Nappe, 4 – Dob-
šinská adová Jaskyňa conglomerates. Normalization by Evensen
et al. (1978). Data sources: Ivan & Kronome (1996), Hovorka &
Spišiak (1993) and unpublished data.
RELICS OF THE MELIATA OCEAN CRUST: GEODYNAMIC IMPLICATIONS 251
formation of magmatic minerals (clinopyroxene, plagioclase,
ilmenite and olivine) to a diverse association of metamorphic
minerals such as Ca amphiboles (pargasite, magnesiohorn-
blende, actinolite), Na-amphibole (riebeckite), Na-Ca amphib-
ole (winchite), albite, chlorite, epidote, biotite, titanite, car-
bonates and ore minerals (Horváth 1997, 2000). The
succession of the mineral growing indicates at least three stag-
es of metamorphism: (1) oceanic ridge metamorphism over-
printed by (2) HP/LT stage followed by (3) retrogression in
greenschist facies conditions, although there is an alternative
interpretation (e.g. Horváth 2000).
Geochemical signatures of basic magmatic rocks of the
BVOF vary between N-MORB and E-MORB (Harangi et al.
1996). E-MORB type displays mildly dipped chondrite nor-
malized REE pattern (Fig. 5) and enrichment in HFSE in rela-
tion to N-MORB (Fig. 7).
The age of magmatic rocks of the BVOF was interpreted as
Triassic (Ladinian) on the basis of paleontological dating of
red radiolarites (Kozur 1991). Direct geochronological dating
of gabbrodolerites indicates some older age, probably lowest
Triassic (Horváth 2000).
Darnó Hill Formation
The Darnó Hill Formation crops out as a small (several km
2
)
area SW of the Bükk Mts. It represents, similarly to the Melia-
ta Formation, a mélange of olistoliths of abyssal sediments
and ophiolitic rocks in the turbidity sediment matrix (Kozur
1991). According to Downes et al. (1990) the ophiolitic olis-
toliths are composed of basalts, dolerites and gabbrodolerites.
In spite of the varying intensity of LP/LT alteration (spilitiza-
tion), the original magmatic structures and textures are well
preserved. Basalts erupted as pillow lavas or sheet lava flows.
Clinopyroxene, plagioclase, ilmenite and rare olivine are the
main constituents in the fresh basalts. In altered varieties they
are replaced by chlorite, albite, epidote, carbonate and leucox-
ene.
Two trends are observable in the chemical composition of
basalts: some of them are geochemically close to E-MORB
types (Downes et al. 1990) similar to BVOF basalts, other
ones remind of BABB type (cf. Harangi et al. 1996) similar to
the Meliata Unit basalts (Fig. 5, Fig. 7).
The age of ophiolitic rocks, supposed to be Triassic (Ladin-
ian), is based on paleontological dating of red radiolarites (De
Wever 1984), whereas the age of the mélange matrix was re-
ported by analogical method as Middle Jurassic (Kozur &
Mock 1988; Dosztály & Józsa 1992).
Dobšinská adová Jaskyňa conglomerates (DLJC)
The most complete evidence for the oceanic crust composi-
tion of the Meliata Ocean comes from the Upper Cretaceous
Gosau-type conglomerates from Dobšinská adová Jaskyňa
village (Slovenský raj Mts). The Cretaceous formation at this
locality is composed of conglomerates, sandstones, marly
slates and limestones. Conglomerates build up the lowermost
part of the sequence and are represented by two types with the
different clastic material. Ophiolitic rocks are the principal
clast type in one of them only. They are accompanied here also
Fig. 5. Chondrite normalized REE patterns for metabasalts and met-
adolerites – relic of the Meliata Ocean from the southern part of
the Inner Western Carpathians. Patterns with differentiated LREE/
HREE enrichment belong to the E-MORB type. Explanations: 1 –
Bódva Valley Ophiolite Formation, 2 – Darnó Hill Formation, 3 –
Inke and Tóalmás boreholes. Normalization by Evensen et al.
(1978). Data sources: Downes et al. (1990), Harangi et al. (1996)
and unpublished data.
by subordinary amounts of marble, cherts, sandstone, calc-al-
kaline basaltic andesite and rhyolite clasts. All clasts are dif-
ferentially rounded in accordance with their resistance. The
conglomerate is poorly sorted and it has serpentine matrix
(Hovorka et al. 1990).
Almost all the components of the typical ophiolite sequence
(e.g. Moores 1982) have been found among clasts of this con-
glomerate type: radiolarites, basalts, dolerites, isotropic gab-
bros, cumulate gabbros, cumulate pyroxenites and spinel peri-
Fig. 6. Hf/3-Th-Ta diagram (Wood 1980) for metabasalts and met-
adolerites representing Meliata Ocean relics in the northern part of
the Inner Western Carpathians. Mixing trend between N-MORB
and arc characteristics is typical for several recent back-arc basins
(e.g. Falloon et al. 1992). Explanations: symbols – see Fig. 4; A
– N-MORB, B – E-MORB, C – WPB (alkali), D – basalts of
destructive plate margin (IAT and CAB). Data sources: Ivan &
Kronome (1996) and unpublished data.
252 IVAN
dotites (Ivan et al. 1998). Basalt clasts with glassy, intersertal,
variolitic, subophitic or ophitic textures were initially com-
posed of clinopyroxene, plagioclase and volcanic glass with a
lesser amount of olivine and ilmenite. The same association
(except glass) has been found in dolerites, whereas the associ-
ation in gabbros comprises orthopyroxene, clinopyroxene, pla-
gioclase and ilmenite. As a result of the metamorphic alter-
ation, these associations were variably replaced by
Ca-amphiboles (often gradually changed from pargasite
through magnesiohornblende to actinolite with decreasing of
temperature in gabbros), albite, chlorite, epidote, prehnite,
pumpellyite, grossularite, carbonate and smectite. Pyroxenites
were almost fully transformed to actinolite rocks, peridotites
to lizardite-chrizotile or rarely to antigorite serpentinites.
Metamorphic alteration evolving from the amphibolite (in
gabbros only) to lower greenschist facies conditions resembles
typical oceanic-ridge type metamorphism. Relatively numer-
ous metagabbro clasts with grossularite, pumpellyite, actino-
lite and prehnite do not exclude later overprint by a very low-
grade metamorphic stage. Blueschist clasts, rarely found in
conglomerate as a product of HP/LT metamorphism, are com-
posed of Na-amphibole (glaucophane), Na-Ca-amphibole, act-
inolite, epidote, albite and titanite. Some of them only seem to
have originated from ophiolite protolith.
Trace element distribution in several studied basaltic clasts in-
dicates their similarity to N-MORB, although arc-like signature
has been also identified in basalt forming small (several meters)
body located near the base of the conglomerate layer. The
geochemical characteristics of gabbros are similar to those from
oceanic floor with positive Eu anomaly for cumulate gabbro.
The Triassic age of ophiolite clasts in Cretaceous DLJC is
most probable because they are associated with red radiolarite
clasts of the paleontologically proven Triassic age (Múčková
1989).
Geodynamic and tectonic implications
In all the above-mentioned formations a fragmentary char-
acter of oceanic crust relics of the former Meliata Ocean is a
typical feature. The relics of the Meliata Ocean can be referred
to as incomplete dismembered ophiolite sequences including
only deep-sea sediments, pillow lavas and sheet lava flows, in
smaller amounts also subvolcanic members (from the sheeted
dyke complex?) and scattered isotropic gabbros. All the above
mentioned rocks belong to the uppermost part of the oceanic
crust. The presence of the real complete oceanic crust in the
Meliata Ocean, produced in a zone similar to the mid-ocean
ridge, follows from the association of magmatic rocks in the
DLJC. In spite of this fact the Meliata Ocean was never a wide
ocean separating large continents. The variability of basalt
composition from the arc-like types through geochemical
types close to BABB up to almost typical N-MORBs is identi-
cal with the products of magmatic evolution during opening
and spreading of recent back-arc basins (e.g. Price et al. 1990;
Gribble et al. 1996, 1998). Arc-like or back-arc basin basalts
are related to the carbonate or clastic deposition (Bôrka
Nappe), whereas the types approaching typical N-MORB oc-
cur together with black cherts or red radiolarites. This change
in sediment type can also be interpreted as a result of basin
spreading and deepening. E-MORB types or transitional types
between E- and N-MORB, identified in the BVOF and Darnó
Hill Formation, are also known from recent back-arc basins
where they are interpreted as a result of the partial melting of
mantle sources previously affected by older mantle plumes
and generated in the initial stages of the basin opening (Fal-
loon et al. 1992; Wendt et al. 1997; Ewart et al. 1998). There is
evidence for the existence of such types of mantle sources also
from Early Paleozoic and Carboniferous volcanic rocks of the
Inner Western Carpathians (Ivan et al. 1994; Ivan 1997).
The maximum extent of the Meliata Ocean is related to the
Middle Triassic time, when it could have reached a width ap-
proximately several hundreds km. This estimation is based on
basalt geochemistry, sediment lithology and analogies to re-
cent back-arcs (cf. Gribble et al. 1996, 1998).
Formation of the Meliata Ocean as a back-arc basin had to
be related to the subduction or early post-orogenic settings. It
seems likely that the Meliata Ocean was founded and opened
inboard of the Permian volcanic arc, the vestiges of which are
traceable in the Inner Western Carpathians (Krompachy
Group) or southern Central Western Carpathians (Permian for-
mations of the Veporic Unit) in the form of subaerial calc-alka-
line volcanism producing lavas from basic to acid in composi-
tion (Vozárová & Vozár 1988; Ivan 1996). The products of
such a volcanic activity have been also found together with
HP/LT metamorphosed basalts of BABB signature and the
Meliata Ocean affinity forming clasts in the Cretaceous con-
glomerates of the Klape and Manín Units of the Pieniny Klip-
pen Belt (Ivan et al. 1999). Late Permian opening of the Meli-
ata Ocean on the active continental margin was supposed by
Stampfli (1996, 2000) in his global plate tectonic reconstruc-
tions. Following the dynamics of a back-arc basin opening at
the present time (cf. Doglioni et al. 1999) it seems to be possi-
ble that the dipping of the subduction zone, above which the
Meliata Ocean was opened, was to the west. This idea seems
Fig. 7. Hf/3-Th-Ta diagram (Wood 1980) for metabasalts and met-
adolerites – relic of the Meliata Ocean from the southern part of
the Inner Western Carpathians. Explanations: symbols – see Fig.
5; A – N-MORB, B – E-MORB, C – WPB (alkali), D – ba-
salts of destructive plate margin (IAT and CAB). Data sources:
Harangi et al. (1996) and unpublished data.
RELICS OF THE MELIATA OCEAN CRUST: GEODYNAMIC IMPLICATIONS 253
to be supported by the paleomagnetically proven original posi-
tion of all future small lithospheric segments of the Alpine-
Carpathian-Pannonian realm, which probably formed together with
Adria, Sardinia, Corsica and Greece a compact piece of land of
south-north orientation adjacent to the eastern side of the French
Massif Central during the Permian (Neugebauer et al. 2001).
The closure of the Meliata Ocean resulted from its subduc-
tion connected with the formation of the accretion wedge of
Franciscan type (Kozur 1991). The first to be consumed were
the oldest sedimentary complexes with some volcanic rocks
(arc-like or BABBs) from the basinal margin. They underwent
subduction-related HP/LT metamorphism followed by exhu-
mation and now they represent the substantial part of the high-
pressure metamorphosed relics of the Meliata Ocean. Low-
grade (LP/LT) metamorphosed relics were originally
generated mostly during a more developed stage of the Melia-
ta Ocean opening (basalts similar to N-MORB). They were ac-
creted into mélanges probably by peeling of the upper part of
the oceanic crust in accretionary prism because many analo-
gies in geological structure between such terrain (see Kimura
& Ludden 1995) and particularly the Jaklovce Formation can
be found. There is indirect evidence only for the obduction of
the complete oceanic crust sequence onto arc crust following
from the petrographic variability of clasts in the DLJC. The
closure of the Meliata Ocean was dated as Middle Jurassic
(Bathonian to Callovian/Oxfordian;) using the paleontologi-
cally estimated age of radiolarites of the mélange matrix (Ko-
zur 1991; Mock et al. 1998).
The recent tectonic position of the Meliata Ocean crust rel-
ics is extremely complex because the pile of nappes and slices
created in the Jurassic accretion wedge was involved in the re-
peated nappe structure formation during the Cretaceous (cf.
Plašienka 1997). The latter event is also responsible for the
formation of salinar mélanges by tectonic mixing of oceanic
crust relics with Permian evaporites (Kozur 1991). The ero-
sion of nappes containing the rocks of the former Meliata
Ocean in the Upper Cretaceous led to their recycling into Gos-
au-type conglomerates.
The complicated tectonic position of the relics of the Melia-
ta Ocean floor and marginal rocks render difficult a recon-
struction of the paleogeography, subduction trend or original
position of the suture of the Meliata Ocean. According to Neu-
bauer et al. (1999) this suture was situated between the Aus-
troalpine units on the one side and the Southalpine or Tisia
units on the other side. Direct evidence concerning the geolog-
ical structure of the former continental margins of the Meliata
Ocean derives from olistoliths or clasts of arc-related magmat-
ic rocks (rhyolites, calc-alkaline basalts probably Permian or
Triassic in age) in the Meliatic Fm. or in the DLJC and also
from HP/LT metamorphosed non-oceanic rocks in the Bôrka
Nappe – material of the overriding lithospheric plate located
immediately above the subducting oceanic plate or a continen-
tal margin temporarily involved into the subduction zone (e.g.
Chemenda et al. 1996). These rocks are represented by meta-
morphosed clastic sediments with sporadic rhyolites (Permi-
an?; Faryad 1995b) and calc-alkaline basic volcanic rocks in-
terlayered by pelitic sediments (Ivan 1999) or amphibolites
and gneisses with HP/LT overprint (Faryad 1988), both proba-
bly Early Paleozoic in age.
Several controversial models of the paleogeographical evo-
lution of the Tethyan Realm during the Mesozoic time includ-
ing also the Meliata Ocean (Kozur 1991; Michalík 1994; Neu-
bauer 1994; Stampfli 1996; Channel & Kozur 1997; Kovács
1997; Zacher & Lupu 1998; Gawlick et al. 1999; Neugebauer
et al. 2001) have been proposed. Among these models the con-
ception by Stampfli (1996, 2000), which interpreted the Meli-
ata Ocean as an individual back-arc basin separated by a Per-
mian island arc from Paleotethys, seems to be, from the
geodynamic point of view, in good accordance with the results
obtained from the geological study of the Mesozoic oceanic
crust relics in the Inner Western Carpathians. But the extent
and spatial position of this back-arc basin to the coeval large
oceans referred to as Paleotethys and Neotethys still remains
unclear and, the alternatives of its continuation in the Inner
Hellenides, Inner Dinarides, Transylvanides and Northern Do-
brogea, are a matter of discussion (e.g. Zacher & Lupu 1999).
New light could be cast on this problem by kinematical recon-
structions of the ALCAPA and Tisia block movements, which
indicate important dextral displacement of the ALCAPA block
to the NE along the Middle Hungarian Zone connected with
the transport of some structural units of South Alpine-Dinarid-
ic affinity as far as the Bükk Mts – Inner Western Car-
pathians area during the Tertiary (Fodor et al. 1998; Haas et al.
2000). If such an interpretation is correct, then the Meliata
Ocean relics could be directly related to Hellenide-Dinaride
ophiolites and could represent their original northwestern con-
tinuation. The same idea was formerly supported by Kovács
(1997), who argued for it pointing out the presence of oceanic
basalts associated with the Ladinian/Carnian red radiolarites in
both the above mentioned ophiolitic complexes. Unfortunately
lack of reliable data on the magmatic rock geochemistry, geo-
logical structure and evolution of the Hellenide—Dinaride
ophiolite belts do not allow us to trace the position of the Meli-
ata Ocean relics herein. The majority of ophiolitic rocks of
these belts are supposed to be Jurassic in age and they are in-
terpreted as relics of one or two oceans (e.g. Vardar and Pindos
Oceans; Channells & Kozur 1997) younger than the Meliata
Ocean. Jurassic magmatic rocks with MORB signature were
also found in the close neighborhood of the southernmost Me-
liata Ocean relics in the Bükk Mts, but the relation of this in-
complete ophiolite complex to those in the Dinaride belts is
still unclear (Downes et al. 1990; Aigner-Torres & Koller
1999). According to Pearce et al. (1984) the Dinaride ophio-
lites were formed in a supra-subduction zone geodynamic set-
ting, because they are geochemically more variable in compar-
ison to typical oceanic rocks (or Alpine ophiolites) including
not only MORB but also IAT (island arc tholeiite) or boninitic
types. Although such a characterization of Dinaride ophiolites
may be too generalized (e.g. Bosnian ophiolites belong wholly
to the N-MORB, exceptionally to the E-MORB type –
Trubelja et al. 1995), it is fully applicable also for the Meliata
Ocean relics. Speculation, that the Meliata Ocean relics together
with Hellenide-Dinaride ophiolite belts are really remnants of
one or more (parallelly opened?) back-arc basins, seems to be
reasonable, but the incompatibility of the plate-tectonic models
of the Mesozoic-Tertiary evolution of the western Tethyan
Realm including its small oceanic basins clearly indicates that a
great amount of exact data is still missing.
254 IVAN
Conclusions
Mineralogical, petrological and geochemical data concern-
ing the Meliata Ocean crust relics together with their geody-
namic implications led us to the following conclusions:
• Oceanic crust relics of the Triassic-Jurassic Meliata
Ocean are represented by dismembered ophiolites forming
slices and blocks in Jurassic olistostroma and mélanges or re-
cycled material in conglomerates
• Metamorphosed basalts and dolerites from the upper part
of the former oceanic crust dominate within the Meliata
Ocean crust relics
• Variations in basalt composition from arc-like types
through BABBs to the types similar to N-MORB together
with the changing of enclosing sediments from carbonate to
deep-sea ones in the Meliata Ocean relics are related to the
same magmatic and sedimentary evolution operating in the
course of the opening and spreading of recent back-arc basins
• Jurassic subduction and the following exhumation was
experienced mostly by the marginal parts of the Meliata
Ocean with magmatic rocks of the initial stage of opening,
whereas magmatic rocks of the evolved stage were usually
obducted or accreted in an accretion wedge
• The Meliata Ocean ophiolite suture in its original posi-
tion was destroyed by the following tectonic processes and
nappe formation in the Cretaceous time
• The Meliata Ocean was probably opened as a back-arc
basin inboard of a Permian magmatic arc, the vestiges of
which are traceable in the nappe piles on both sides of the In-
ner and Central Western Carpathian boundary
• Continental margins of the Meliata Ocean comprised in
their geological structure Permian(?) arc-related volcanic
rocks together with an arc-related volcano-sedimentary com-
plex, amphibolites and gneisses all probably Early Paleozoic
in age
• The Meliata Ocean relics could be directly related to Hel-
lenide-Dinaride ophiolites representing originally their north-
western continuation displaced into their present-day position
by microplate motions in the Miocene
Acknowledgments: The author is indebted for the support of
this work by the VEGA Grant 1/6000/99. He is also grateful
to A.H.F. Robertson (University of Edinburgh), D. Plašienka
(Geological Institute of Slovak Academy of Sciences) and an
anonymous reviewer for constructive comments and reviews,
which greatly improved the manuscript.
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