150

GEODYNAMIC EVOLUTION OF THE BLACK SEA REGION

Shota Adamia*, Ali Yılmaz**, Manana Lordkipanidze***, Irakli Shavishvili***,

Tamara Chkotua*** and Alexander Chabukani***

*Tbilisi State University, Department of Geology and Paleontology,380028,Tbilisi, Georgia,

**General Directorate of Mineral Research and Exploration, 06520, Ankara, Turkey,

***Geological Institute, Academia of Sciences of Georgia, 380093, Tbilisi, Georgia.

ABSTRACT

An analysis of the Phanerozoic evolution of the Black Sea region (Fig.,1) shows

that at least from the Paleozoic onwards, the region evolved as an active margin of the

Northern Tethys comprising oceanic and continental back-arc systems. Counterparts

of many of the Caucasian-Eastern Pontian structural units can be traced in Western

Pontides, Balkans and Carpathians. Continuous development of the Paleothethys-

Tethys throughout the Paleozoic-Mesozoic-Early Cenozoic is indicated by the

presence of Paleozoic to Upper Cretaceous oceanic rocks, of the Lower Paleozoic to

Eocene supra-subductional magmatic assemblages and by an uninterrupted deep

marine Devonian to Late Eocene sedimentation in the Dizi basin of the Greater

Caucasus. In this connection, the Dizi series represent interarc or back-arc

associations. The whole region seems to represent a West Pacific type long living

accretionary assemblage of the Lesser Caucasian - North Anatolian-Vardar branch of

the Tethys.

INTRODUCTION

Does the geological record of the Eastern Mediterranean belt reflect history of

several oceans or it is issued from a single ocean Tethys - a great gulf of the eternal

Pacific which remained permanently open for at least 500 Ma before it was closed

some 20-30 Ma ago? The present paper aims to contribute to the solution of this long-

living controversy basing on correlation of the Phanerozoic paleogeographical units of

the Eastern Mediterranean. The main controversy is related to the Paleozoic-Early

Mesozoic position of this region. The present authors consider the above regions as

parts of the northern active margin of the permanent Paleozoic-Early Cenozoic ocean

151

of the Tethys (Adamia et al., 1977a,b, 1981, 1984, 1987, 1995). Others defend South

Tethyan position of the Pontides and the Transcaucasus in the Paleozoic-Early

Mesozoic (Belov, 1981, Şengör et al., 1985, Kazmin, 1989). In this paper, we do not

suggest new palinspastic models. Our main goal is to reconstruct a general trend of

Phanerozoic development and displacement of this key region through synthesis of

recent structural, stratigraphical, petrological-geochemical, radiometric and

paleomagnetic data. Much of this recent evidence for the Caucasus and Eastern

Pontides is as yet unpublished or is printed in local journals unavailable to world

geological community.

LESSER CAUCASIAN-NORTH ANATOLIAN-VARDAR

OPHIOLITIC SUTURE

The Lesser Caucasian-North Anatolian-Vardar ophiolitic axes separate the

Paleozoic-Early Mesozoic domain of subduction-related magmatism, metamorphism

and deformation, belonging to the North Tethyan geological province from the domain

with Precambrian basement and the Paleozoic-Early Mesozoic shallow-marine

predominantly carbonate cover of the South Tethyan (Gondwanian) passive margin.

Many authors interpret this ophiolitic axes as the main suture of the Paleotethys-

Tethys (Adamia et al, 1977a, 1981, 1984, 1987).

152

Figure, 1, Paleotectonical schematic map of the Eastern Mediterranean belt. Suture zones:

1.Paleotethys-Tethys (Northern Anatolian-Lesser Caucasian), 2.Zagros-Oman,

3.Southeastern Anatolia, 4.Alpine fordeep molasse depression on the Euro-Asiatic

continent, 5.Southern border of the continent, 6.Back-arcs, 7.Island volcanic arcs and

microcontinents, 8.Gondwanian fragments, 9.Arabian promontory, 10.Interarc troughs.

EE-Eastern Europe, GC-Great Caucasus, IC-Inner Carpathyans, SG-Srednegora, R-

Rodopes, M-Moezia, PC-Precarpathyan, MC-Mountain Crimea, KO-Kotel; WP-Western

Pontides, EP-Eastern Pontides, K-Kure, STC-Southern Transcaucasia, D-Dizi, CA-

Central Anatolia, ECI-Eastern Central Iranian, WB-Western Black Sea, EB-Eastern Black

Sea. WPC-Western Precaucasia, S-Scythia, EPC-Eastern Precaucasia, AT-Adjara-

Trialeti, AB- Artvin-Bolnisi; TC-Transcaucasia, T-Talisch, SC-South Caspia,SK-

Sakarya,NA-North Anatolia, BK- Baiburt-Karabakh,LC-Leser Caucasus,Z-Zagros,Tu Turan.

The Lesser Caucasian (Sevan-Akeran) part of the suture is built up of

strongly tectonised dismembered Paleozoic-Mesozoic ophiolites (nappes and

melanges) of the root zone (Knipper, 1975; Sokolov, 1977; Hasanov, 1986; Adamia et

al., 1987; Kariyakin and Aristov, 1990). Age, structural relationship, petrology, rare

elemental and isotopic signatures of the ophiolitic magmatic series as well as lithology

of the related sediments are studied in great detail. According to data of Zakariadze et

al. (1983, 1986, 1988), Zlobin and Zakariadze (1986), Bogdanovski et al., 1992)

mantle tectonites forming the matrix of the ophiolitic melanges within the nappes and

in the root zone are transitional between abyssal peridotites and peridotites of active

margins. Magmatic rocks are represented by subductional tholeiitic, boninitic and

withinplate type mildly alkaline and tholeiitic volcanics. Arc-type tholeiites are

represented by a complete ophiolitic assemblage - cummulates, massive intrusive

rocks, dyke swarms and pillow-lavas. Massive boninitic plutons are inttruded into

layered cummulates of the tholeiitic series. The age of the boninitic intrusive rocks is

Bathonian-Callovian (K/Ar ages of rocks and minerals - are 168+8 Ma, U/Pb, age of

zircon from quartz-diorite 160+4 Ma). Sm/Nd ages of tholeiitic gabbro-norites are

153

Triassic - 226+13 Ma (Lev-Chai) and 224+0.3 (Alktikovshan). Both are characterized

by a low Nd (5.1+0.4 and 4.0+0.3 respectively). Rare elemental and isotopic

signatures point to supra-subductional origin of the tholeiitic and boninitic series. In

volcanic-radiolaritic assemblages volcanites are represented by subductional tholeiites

and also by boninitic series, high Mg basalts, andesites (boninitess), high Mg rhyolites.

Oceanic island type mildly alkaline basalt-trachyandesitic series are also present

(Fig., 2,3).

Paleontological age of the volcanics ranges from Upper Paleozoic and Triassic

to Upper Cretaceous (Adamia et al., 1987; Knipper, 1990). The related sediments are

radiolarites, often with a considerable admixture of argilliceous matter and enriched in

Fe and Mg. Intercalations of micritic limestones point out that periodically

sedimentation occurs above the CCD (lysocline). Rare wedges of the Upper Jurassic

reef limestones, surrounded by volcanic-limestone clastics and the Upper Cretaceous

(Turonian) rudist-bearing limestones mark seamounts and islands. Thus in similarity to

many other well studied ophiolitic assemblages of Eastern Mediterranean and the

Lesser Caucasin ophiolites are of supra-subductional origin. The character of

sediments shows that in their major part the Mesozoic oceanic arc-back arc have

been isolated from influx of continent derived clastics and represented Marianas and

Izu-Bonin type intraoceanic structures.

Upper Triassic to Upper Cretaceous oceanic assemblages are indicative of

continuous oceanic conditions during the Mesozoic. Presence of separate blocks of

the upper Paleozoic oceanic rocks confirmed by radiometric and faunistic datings is of

a major importance. In the north-western part of the Sevan-Akeran belt at the

Armenian-Turkish border garnet amphibolites occur as blocks in ophiolitic melange

nappe (Fig., 4) yielded 330 24 Ma Rb/Sr isochrom age (Meliksetian et al., 1984). Nd

and Sm isotopic signature and REE geochemistry indicate that the protholith

corresponds to basalts and basaltic andesites of oceanic island arc affinities

(Zakariadze et al., 1988).

North of lake of Sevan the ophiolitic melange nappe comprises huge blocks of

alternating basalts, pelitic limestones and calcarenites.

154

Figure, 2, TiO -FeO /MgO diagram for the Jurassic-Neocomian volcanics of the Lesser Caucasian

ophiolitic suture.

1.Tholeiites from Ipijak nappe; 2. Alkaline basalts from Ipijak nappe; 3. Basaltic andesites from

Kilichli. I-IV-axial lines for: !-MORB, II-IV-oceanic islands (II- Galopagos, III-Hawaii, IV-Iceland).

V-VIII- volcanic areas of primitive island arcs: V -Tonga, VI-Mariana, VII-VIII-Fiji. Hatched area -

field of ophiolitic volcanics of Eastern Mediterranean, dotted lines - boundary of the Middle-

Upper Cretaceous volcanics from the Sevan-Akera (Lesser Caucasus) ophiolites

(Lordkipanidze, 1986).

155

Figure, 3, FeO -FeO/MgO diagram for the Jurassic-Neocomian volcanics from the ophiolitic suture of

the Lesser Caucasus for explanations see Fig. 2. (Lordkipanidze, 1986).

156

Figure, 4, Geologial map and cross-section of Amasia region (after Sokolov,1974): 1- Neogene-

Quaternary deposits, 2-Paleogene, volcanogenic-sedimentary pile. 3- Paleogene sandy-clayey

pile. 4- Upper Cretaceous-carbonate pile. 5-Upper Cretaceous, clastic material pile, 6-

ultrabasites, serpentinites, serpentinitic ultrabasites, 7-serpentinites, breccias of serpentinies, 8-

gabbroids, 9-effısive radiolaritic serias: A-effusives, B-siliceous rocks, 10-zones of serpentinitic

melange, 11-Metamorphic rocks (their Rb-Sr age being 330±42 Ma.Meliksetyan et al., 1984),

12- Blocks of limestones, 13- Granitoids, 14- Zones of hydrothermally altered rocks,

15- Stratigraphic boundaries, 16-Line of geological profile.

The limestones yielded few conodonts and among them the Middle Carboniferous-

Lower Permian Diplognethodus Kozur et Maril. By bulk rock chemistry volcanics are

withinplate mildly alkaline and tholeiitic basalts (Karyakin and Aristov, 1990). Thus,

earlier numerous K/Ar datings pointing to the Paleozoic oceanic assemblages within

the Lesser Caucasian ophiolitic belt are proved to be realistic (Fig. 5,6).

Within the North Anatolian ophiolitic belt, harzburgitic serpentinites, various

gabbroes, including cummulates, tholeiitic basalts of MORB and IAT type, withinplate

type alkaline and tholeiitic volcanic rocks of the Jurassic to Upper Cretaceous and

unknown age are described in the Upper Cretaceous ophiolitic melanges and tectonic

sheets of ophiolites emplaced in the Late Senonian. It is to be stressed that

Bergougnan (1987) points out the Upper Paleozoic (260 11 Ma K/Ar age)

plagiogranites related to gabbro and ultrabasic cummulates in the Kesish-Dag

ophiolitic massif of Eastern Pontides. It is also to be noted that the Permo-Triassic

Karakaya complex consisting of the forearc type melanges and ophiolites,

metamorphosed mainly in greenschist-blueschist facies, is spatially very close to the

157

North Anatolian suture zone and in its eastern part (Erzincan area) merges with the

latter (Tekeli; 1981; Adamia et al., 1987; Ustoomer and Robertson, 1995). This belt by

character of its sedimentary and magmatic facies and by the type of metamorphism

and tectonics is indicative of forearc setting (Ustaomer and Robertson, 1992, Şengün,

1995). The Karakaya complex which is composed of stacked tectonostratigraphic

units is interpreted in terms of oceanic subduction and accretion (Pickett et

al.,1995).The Karakaya volcanics by their petrochemical-geochemical signatures

belong to MORB, withinplate and arc-type association (Mesched, 1986; Picket et al,

1995).

Farther West ophiolites of the Vardar zone evidently include the Triassic

oceanic assemblages, Jurassic basic-ultrabasic rocks and Late Cretaceous oceanic

rocks. Some of them are distinctly subduction-related (Karamata, 1988).

To conclude, the Lesser Caucasian-North Anatolian ophiolitic belt considered

here as the main suture of the Tethys ocean comprises the Upper Paleozoic to Upper

Cretaceous ophiolitic assemblages. The major part of these latter assambleges by

their rare elemental and isotopic signatures distinctly subduction-related. This allows

to infere that the ocean itself existed earlier, probably during the whole Paleozoic.

Development history of the North Tethyan island arc system is strongly in favour of

this conclusion.

NORTH TETHYAN ISLAND ARC SYSTEM

The North Tethyan island arc system was evolving from the Early Paleozoic up

to Early Cenozoic and experienced numerous rearrangements during its long history.

The three EW trending chains of the Paleozoic-Cenozoic and Paleozoic-Mesozoic

island arc fragments occur in the present-day Caucasus (Fig. 7,11).

The southernmost Transcaucasian island arc directly adjacent to the Lesser

Caucasian ophiolitic belt seems to be a composite feature consisting of the Northern

and Southern Transcaucasian parts (Lordkipanidze et al., 1984., 1988).

Southern Transcaucasus is directly continuous into Eastern Pontides and still

farther west links with Western Pontides, Phodope massif and the Variscan granite-

metamorphic massifs of inner Carpathians.

150

Figure, 5, Schematic columnar section of the Touragchai zone.: 1.Arc volcanics and volcanoclastics,

2.Mainly limestone, 3.Clastics, olistostromes, 4.Ophioclastics, 5.Ophiolitic melange, 6.Volcanics

with radiolarites, 7.Volcanics and limestones, 8.Basal conglomerates and limestones (after

Karyakin and Aristov,1990).

1

6

150

Figure , 6, TiO -FeO/MgO diagram for the basalts of the Touragchai zone.

a-basalts from the Lower Cretaceous volcanic-radiolarite formation, b-basalts from the Upper

Paleozoic volcano-carbonatic formation. OIB-ocean island basalts, MORB-mid-ocean ridge

basalts, IAR - island-arc type basalts (Karyakin and Aristov, 1990)

Figure, 7, Distribution of the Paleozoic volcanics and granitoides of the Caucasus and Eastern

Pontides,

1-6-subduction-related volcanics: 1-calc-alkaline series, 1a-differentiated toleiites, 1b-

shoshonites, 2-immature island-arc series, 3-granites,4-back-arc volcanics, 5-MOR-type

volcanics,6-withinplate volcanics, IK-Indol-Kuban and TC-Terek-Caspian fardeeps, S-Scythian

young platform, FR-Forerange and MR-Main Range of the Great Caucasus, MT-Main Thrust,

R-Rioni and K-Kura intramountain depressions, Dz-Dzirula, KH-Kkhrami, L-Loki and M-Murguz

salients, TC-Transcaucasus, LK-Loki-Karabakh zone, EP-Eastern Pontides; NA-LK-North

Anatolian-Lesser Caucasian ophiolite suture, A-Aras depression; dashed line-state boundary

between Caucasian states with Turkey and Iran (Lordkipanidze, 1986; Lordkipanidze et

al.,1988; Adamia et al.,1987, 1995; Aktimur et al.,1992; Bektaş and Güven,1995; Aydın et

al.,1995; Korkmaz et al.,1995; Tokel, 1995).

151

Figure, 8, Distribution of the Triassic-Lower Jurassic volcanics (Tokel et al., 1995; Adamia et al., 1995;

Tunoğlu and Batman, 1995; Şengün, 1995; Yılmaz et al., 1996).

Figure , 9, Distribution of the Middle Jurassic, Upper Jurassic and Lower Cretaceous volcanics. Upper

Jurassic withinplate volcanics are shown by small symbols (Lordkipanidze, 1986; Lordkipanidze

et al., 1988; Bergougnan, 1987; Korkmaz, 1995; Adamia et al., 1995).

152

Figure, 10, Distribution of the Albian-Upper Cretaceous volcanics (Lordkipanidze, 1986; Lordkipanidze

et al., 1988; Bektaş and Güven, 1995; Tokel, 1995; Adamia et al., 1995).

Figure, 11, Distribution of the Cenozoic volcanics. Neogene-Quaternary volcanics are shown by small

symbols (Lordkipanidze, 1986; Lordkipanidze et al., 1988).

153

The South Transcaucasian -East Pontian arc segment consists of the two structural units. In its southern frontal part the so-called Baiburt-Karabakh unit comprises strongly deformed and in many parts imbricated assemblages, unconformably overlain by the Middle and Upper Jurassic, also by the Upper Cretaceous arc-type volcanic-sedimentary sequences. Imbricated and isoclinally folded Upper Paleozoic (?)-Lower Mesozoic black slate-chert-diabase sequences, slivers of plagiogranites and plagiogranite-gneisses, blocks of gabbro-diabases, pillow basalt-radiolaritic slices, small wedges of serpentinitic melange, mafic to ultramafic cummulates are present here together with the Jurassic-Lower Cretaceous volcanic-turbiditic sequences. Pre-Liasssic and pre-Upper Jurassic episodes of ophiolite emplacement are established within this unit (Hasanov, 1986; Adamia et al, 1989, 1992; Yılmaz and Şengör, 1985).

On the AFM diagram pre-Jurasic gabbro and diabases from Ahalt (Yusufeli)

district (Bayburt-Karabakh zone) plot within the oceanic field and form a very

pronounced tholeiitic trend (Fig., 12) K2O-SiO2 (Fig., 13), FeO2 /FeO : MgO, TiO2

/FeO:MgO and TiO2 /P2O3 diagrams (Fig., 14) are in complete agreement and point to

the ophiolitic nature of gabbro and diabases.

Basing on petrological characteristics and analysing rock chemistry, namely

A/CNK (Al2O/CaO, Na2O, K2O) ratios we assume crustal origin of leicogranites from

the Artvin-Bolnisi and Baiburt-Karabakh zones. On the semilogarithmic diagram of

K2O-SiO2 points out Leicogranites plot within the field of continental granophyres (Fig.

13), whereas on the AFM diagram they plot in the granitic field and reveal calc-alkaline

tendencies (Fig., 12).

This unit extends westward and apparently forms the greater part of the Central

Pontides. Pre-Upper Jurassic basement of the latter is dominated by ophiolites. The

northernmost unit of the Central Pontides-Kure ophiolites consist of strongly deformed

turbidites of Permian to Liassic age and dismembered ophiolites bearing a very

distinct subductional geochemical signature. They are unconformably overlapped by

the Middle Jurassic acidic volcanics and intruded by the Bajossian Kastamonu

granitoids (Ustaömer and Robertson, 1992).

The same unit extends wesward into Western Pontides (Ankara accretionary

wedge) and here too comprises pre-Jurassic ophiolites and metaophiolites. Its

analogous feature in Balkans seems to be Circum-Rhodope belt with strongly

deformed and imbricated Late Paleozoic to Early Cretaceous volcanic and

sedimentary asemblages.

This southern frontal zone of the North Tethyan island arc system comprises

tectonic slices and larger blocks widely differing by their tectonic setting and

metamorphosed under differing P-T conditions. Tholeiitic subduction-related volcanics

of oceanic arc type and volcanoclastics to carbonate turbidites form main bulk of this

unit. They coexist with ophiolites and metaophiolites and it represents a West Pacific

type accretionary complex, formed in the northern active margin of the Tethys

(Robertson et al., 1991; Picket et al., 1995; Şengün., 1995; Adamia et al., 1987,

1995). The pre-Liassic-Upper Triassic and pre-Upper Jurassic (Bajosian-Bathonian)

important accretion events are established within the accretionary complex.

154

The Artvin-Bolnisi unit of the Southern Transcaucasian-East Pontian belt is

characterized by the Paleozoic granite-metamorphic basement (Rubinstein, 1970;

Adamia et al., 1987; Bergougnan.,1987; Aydın et al.,1995).

Figure, 12, AFM ternary diagram. ( For explanations see Fig.,13).

Trends: 1-Tholeiitic, II-Trodjemitic, III-Calc-alkaline.

Figure, 13, Semilogarithmic diagram K2O-Si2O for the basement rocks of the Artvin-Bolnisi Zone:(1-

leucogranites) and Baiburt-Karabakh zone: ( 2-plagiogranites, 3-plagiogranite-porphyries,

4-gabbro and gabbro-diabases of the Akhalt mass).

155

Figure, 14, FeO*- FeO*/MgO (a), TiO2-P2O5 (b) and TiO2-FeO*/Mgo (c) diagrams for Yusufeli (Akhalt)

diabases and gabbros (1) and basalts of Narlık group (2).

156

The latter consists of crystalline schists and magmatitic assembblages including basic-

ultrabasic rocks metamorphosed in greenschiest or amphibolitic facies and is intruded

by the Paleozoic granitoides - older quartz diorites, plagiogranites, tonalites and

younger microcline granites. K/Ar and Rb/Sr ages of both varietes give the Middle-

Upper Paleozoic ages (360-310 Ma). This information is true also for granitic slivers in

the Bayburt-Karabakh unit. Zircons from Loki quartz diorites yielded 370 Ma U/Pb

ages (Bartinski and Stepaniuk, 1992). Ordovician U/Pb ages are established for

migmatites of the Dzirula salient of the granite-metamorphic assemblages (Bartnitski

and Stepaniuk, 1992), whereas K/Ar ages of the Dzirula granitoids are Upper

Paleozoic. These granitoids comprise a narrow SW-NE trending terrane consisting of

steep imbricated slices of the Middle Cambrian to Devonian continent derived fine-

grained sediments, Ordovician (?) and Carboniferous acidic volcanics, dismembered

ophiolites (tectonised Precambrian peridotites, gabbro-amphibolites, diabases), slivers

of mylonitized granittoides and marble wedges. The so-called Chorchana-Utslevi

terrane is on the both sides bordered by mylonitized Paleozoic granitoides. A

geographic trend of petrochemical polarity has been established in the Paleozoic

granitoides of the Caucasus, the alkaline increasing from the South to the North. The

most pronounced increases in K2O content, and the K2O/Na2O ratio, as well as

decrease in CaO content from the South to the North have been established and

increase in concentration of lithophilic elements of the Fe-group was observed in the

same direction. The contents of rare elements is, in general, close to that in

granitoides of mantle genesis. The diorite-granodiorites of the southernmost Loki

salient are characterized by the most primitive levels of trace elements concentration.

The granitoids of the Khrami salient are characterized by an oceanic trend of the ratio 87Sr/ 86Sr=0.7073+0.0018 (Gorokhov et al., 1987; Adamia et al., 1987).

The Western Pontian segment of the arc represents internally imbricated

crystalline complex built up of the two types of basement rocks - the first type consists

of the Precambrian granite-metamorphic basement with unmetamorphosed shallow-

marine cover of Cambrian to Lower Carboniferous sediments intruded by the

Paleozoic granitoids. This assemblage (Paleozoic of Istanbul) is unconformably

overlain by the Upper Carboniferous to Lower Triassic shallow-marine and continental

deposits and andesite-basaltic to andesitic calc-alkaline volcanics. The second type is

metaophiolites (basic lavas, black slates, phyllites, marbles and serpentinites

metamorphosed in greenschiest-blueschist facies - the Karakaya complex). The whole

complex is unconformably overlain by the Liassic sediments. It is widely accepted that

the "crystalline" basement is a part of the European Precambrian-Middle Paleozoic

unit. Recent studies point out the Cambro-Ordovician calc-alkaline volcanism and

Ordovician granitoides in the Bolu massif of the Western Pontides. Inner Pontides or

the so-called "Sakarya continent" of the West Central Pontides are similar to that of

the Western Pontides. Recent studies completed by many authors (Picket et al., 1995;

Şengün, 1995; Ustaömer and Robertson, 1995; Robertson et al., 1996; Evans and

157

Hall, 1990) show that the Karakaya complex manifests the characteristics of a

subduction-related accretionary prism which is unconformably overlaine by Late

Triassic-Jurassic weakly deformed shelf deposites.

Western continuation of the island arc system in Balkans is represented by the

assemblage of tectonic sheets of the Rhodope massif. The nappes are built up of

gneises, granite-gneisses, micaschists, eclogites and amphibolites alternating with the

marble sequences. The rocks are migmatitized and intruded by granitoides of the

Variscan (240-340 Ma U/Pb ages), Upper Cretaceous and Paleogene ages. Tectonic

slices, wedges and budinages of metamorphosed basic and ultrabasic assemblages

are also present. Non-metamorphic cover starts with Senonian. Mostly Phanerozoic

ages of Rhodopean crystalline assemblages are proved by recent data (Ivanov, 1988).

To the North Tethyan arc system belongs the Dumbier crystalline assemblage

of the Nizke Tatra of Slovakia. The assembage is strongly tectonized and along with

granitoids, comprises tectonic slices of the Upper Paleozoic and Mesozoic

sequences. The age of Dumbier metamorphics is determined by the K/Ar, Rb/Sr, U/Pb

methods. All the rocks gave age interval 396-260 Ma. Thus Early to Late Variscan age

of metamorphism and tectonisation is established.

The basic and ultrabasic assemblages are present in the Variscan crystalline

basement in the all above granite-metamorphic massifs of the North Tethyan island

arc system. They occur as tectonic slices and wedges, or budinages and xenoliths in

migmatites, gneisses and granitoids. Without any doubt they are pre-Variscan or Early

Variscan. Cambrian Sm/Nd age (585 my) is established for island-arc type gabbro

from Dzirula salient. Today only North Transcaucasian (Dzirula) and Rhodopean

ophiolites and metaophiolites are studied in sufficient detail (Zakariadze et al., 1993).

The petrological-geochemical studies proved that the major bulk of metaophiolites

present as tectonic slices and wedges in the Chorchana-Utslevi terrane of the Dzirula

massif (Nothern Transcaucasus) and in the nappes of the Rhodope massif (Balkans)

by their rare elemental and isotopic signatures answer to MORB tholeiitic series and

their fractionation trends follow MORB petrological model. By analogy to similar basic-

ultrabasic assemblages of the Western Mediterranean and Sm/Nd age of 810 my for

amphibolites of Chorchana-Utslevi tectonic melange they are attributed to the

Precambrian -Middle Paleozoic ocean floor rocks. A smaller group represented by

country rocks, budinages in metamorphics and xenoliths in granitoids manifest distinct

subductional geochemical signature (Zakariadze et al., 1993).

The Upper Paleozoic-Lower Mesozoic calc-alkaline subareal-shallow

water volcanics are widespread in the Caucasian-Pontian arc system (Fig.VII-7).

Tholeiitic and boninite-type volcanics also occur (Ustaömer and Robertson, 1995;

Adamia et al., 1987; Bergougnan, 1987; Bektaş and Güven, 1995; Aydın, 1995;

Korkmaz et al., 1995; Aktimur et al., 1995; Tokel, 1995).

Related shallow-marine to continental sediments comprise distinctly

Euramarian faunal and floral assemblages. Quite meagre Paleozoic paleomagnetic

evidences also point to north Tethyan position of these units in the Paleozoic (Adamia

et al., 1987).

158

Mesozoic-Cenozoic evolution of the North Tethyan island arc system is marked

by the Triassic, Lower Jurassic, Middle Jurassic, Upper Jurassic-Lower Cretaceous,

Upper Cretaceous and Cenozoic magmatic events.

The Triassic-Lower Jurassic magmatic rocks of subductional origin are

present in the Caucasus-Pontides (Fig., 8). In the frontal accretionary complex these

are island-arc type differentiated magmatic rocks (Fig., 15-17) related to black slates,

Figure, 15, Ti-Cr diagram for the pre-Jurassic-Jurassic basaltoids of the Southern Transcaucasus-

Eastern Pontides: 1.Jurassic basalts of the Bayburt-Karabakh zone from the Yusufeli (Akhalt)

area; 2.Jurassic basalts from the Southern Transcaucasus; 3.Jurassic basaltic andesite from

the Kelkit district (Bergougnan, 1987); 4.Jurassic basalts from the Artvin and Akhalt area. OFB -

Ocean floor basalts, LKT - Low-K tholeiits.

159

Figure, 16, K2O-SiO2 diagram for the Jurassic volcanics of the Eastern Pontides and Southern

Transcaucasus: 1.Jurassic volcanics from the Yusufeli (Akhalt), Hahul and Tortum areas; 2.

Jurassic volcanics from the Kelkit ara, 3. Jurassic volcanics from the Southern Transcaucasus.

I, II and III - boundary between fields of low-, moderate- and high potassium calc-alkaline and

shoshonitic volcanics.

Figure, 17, Spaidegram for the Jurassic volcanics of the Kelkit area.

160

1 - basalt; 2-andesite; 3- dacite; 4-rhyolite (Bergougnan, 1987).

Figure, 18, Ba/La/Yb diagram for the Bajocian volcanics of the Transcaucasus: 1-2, southern belt

(southern and northern parts); 3-4, northern belt (lower and upper parts). The southern belt has

a distinct northward polarity. The northern belt shows a marked increase in alkalinity up-section

(Lordkipanidze et al., 1988).

161

cherts, scarce carbonates and sometimes accompanied by tectonic slices of

serpentinites. The Middle-Upper Norian calc-alkaline dacites and rhyolites, related to

plant-bearing conglomerates and sandstones overlie the Dzirula crystalline basement

of the Northern Transcaucasus. Andesites occuring in the red beds in the North-

Western Pontides belong to the continuous Upper Carboniferous-Lower Triassic

volcanic-sedimentary sequence formed on land and in shallow sea. The latter

overlaps the pre-Variscan-Variscan basement.The Ladinian to Norian calc-alkaline

basalt-andesite-dacite sequences of the Inner Carpathians comprising the fields of

ignimbrites (Pitonak and Spisak, 1988) are formed in similar geodynamic

environments.

We do not seek a direct continuity between these widely spaced

suprasubductional assemblages, but it is important to stress that subduction-related

volcanic activity was continuous throughout the Late Paleozoic-Triassic time. This

points to an uninterrupted development of the oceanic and ensialic island arcs in North

Tethyan realm.

The thick (about 3000m) Lower-Middle Jurassic volcanic piles related to

black slates and volcanoclastic turbidites, sometimes to radiolarian cherts are

widespread in the Baiburt-Karabakh accretionary complex of the Eastern Pontides-

Southern Transcaucasus. The volcanics represent differentiated low- K tholeitiic and

boninitic series of oceanic island arc type (Magakian et al., 1985; Zakariadze et al.,

1986; Bergougnan 1987; Adamia et al., 1995). Geochemistry, isotopic signatures of

volcanic rocks as well as character of associated sediments are compatible with an

oceanic arc.

The Lower-Middle Jurassic subductional magmatic sequences extend into the

northern part of the Central Pontides where they overlie Kure ophiolites (Yılmaz and

Boztuğ, 1989). In the Northern Transcaucasus Middle Jurassic volcanics (about

2000m) are characterized by great diversity of composition (boninites, arc-type

tholeiites, calc-alkaline, shoshotites). The Southern volcanic belt has a distinct

northward polarity (Fig., 18).

The Middle Jurassic episode of granitoid intrusion, deformation, ophiolite

obduction and metamorphism which was very extensive along the northern margin of

the Tethys was followed by the Late Jurassic-Lower Cretaceous subduction-related

tholeiitic magmatic episode which was much weaker and restricted in space in the

Transcaucasus-Eastern Pontides (Lordkipanidze et al., 1988), and is not known in

Western Pontides. Oceanic arc type subductional tholeiites sometimes are

accompanied by tectonic slices of serpentinites and related to metaargilites and

turbidites occur in allochtonous position in Circum-Rhodope belt (Dabovski et al.,

1989).

162

It is to be stressed that recent paleomagnetic data point to North Tethyan

position of the Sakarya microcontinent (terrane), the Western and Eastern Pontides

during the Liassic-Eocene (Evans et al.,1982,1990;Sarıbudak et al.,1989;Channel et

al.,1994, 1996).

The extensive Upper Cretaceous and Paleogene (Fig., 10,11) subduction-

related magmatic belt of the South Transcaucasus-Pontides-Balkans-Carpathians,

overlapping pre-Early Jurassic accretionary complexes and Prevariscan to Variscan

crystalline basement of the Eastern Mediterranean, represented by tholeiitic, calc-

alkaline and shoshonitic series are described in numerous publications (Peccerillo and

Taylor, 1976; Lordkipanidze, 1986; Lordkipanidze et al., 1988; Tokel, 1995). According

to Tokel (1995) elemental variations for Jurassic volcanics of the Eastern Pontides

(Baiburt-Trabzon) show that K, Rb contents and Rb/Sr ratio increase but K/Rb ratio

decrease at given SiO2 content away from volcanic front at the South. This transverse

variation according to the authors indicates the northward subduction and

consequently back-arc opening at the north. In the Transcaucasus the Jurassic island-

arc volcanics also display clear northern polarity (Lordkipanidze et al., 1984, 1988;

Zonenstain and le Pichon, 1986; Kazmin et al., 1987).

North of the Transcaucasian-Eastern Pontian arc segment the Greater

Caucasian Main Range and its northern slopes are interpreted as a fragment of the

North-Tethyan Paleozoic-Lower Jurassic arc (Adamia et al.,1987). It is separated from

the Transcaucasian arc by the marginal basin of the Southern Slope of the Greater

Caucasus. Its basement represents an assemblage of tectonic sheets of metamorphic

rocks intruded by Variscan plagiogranitoids and microcline granites. Petrochemical

studies of granitoids carried out in cooperation with I.Gorokhov and V.Duk (the

Institute of Geology and Geochronology of the Precambrian of Russian Acad.Sci.,St-

Peterburg) show that granitoids resulting from mantle-crustal mixing (plagiogranites) -

A/CNK

163

Eastern and Western peripheries of the Greater Caucasian arc fragment are

covered by the Black and Caspian seas, and no structures existing west and east of

these marine basins can be directly connected with this unit. It is not precluded that

the Greater Caucasian arc fragment belonged to the Scythian-Crimean Paleozoic-

Mesozoic island arc system.

The Late Paleozoic-Early Mesozoic Scythian platform occupies the whole of

the Precaucasus and northern foothills of the Great Caucasus. Its basement is

heterochronous. The oldest Precambrian basement crops out within the northern

foothills off the Greater Caucasus - in the Bechasin zone. The younger folded

basement is built up mainly of the terrigene turbidites and basinal deposits of the

Devonian-Carboniferous, intruded by the Upper Paleozoic granitoids. They are

unconformably overlain by the shallow-marine or continental molasses of the Permian-

Triassic. Upper Paleozoic and Middle to Upper Triassic-Lower Jurassic belts of calc-

alkaline volcanics are extensive. Middle Jurassic arc-type volcanics occur in the

Western Precaucasus-Southern Crimea and Cenomanian-Turonian andesites in the

Mountaneous Crimea. The typical platform cover composed of shelf carbonates and

lagoonal salt-bearing and carbonaceous near-shore facies of the Jurrassic,

Cretaceous and Paleocene-Eocene crops out in the northern slope of the Greater

Caucasus. But in some parts of the Precaucasus and flatland Crimea intensely

deformed basinal turbiditic sequences are present. Thus the northernmost Scythian-

Crimean Upper Paleozoic-Mesozoic arc segment was developing from the Later

Paleozoic up to Late Cretaceous. From the Middle Jurassic onwards it may be

attributed to the Andean type active margin.

INTERARC AND BACK ARC BASINS

Volcanic and sedimentary sequences of Paleozoic to Early Cenozoic interarc and

back arc basins are indentified in the Eastern Mediterranea region (Fig., 1).

Southernmost and the youngest Late Cretaceous-Paleogene en-echelon

interarc basins are Talysh-South Caspian and Adjara-Trialeti-Eastern Black sea

basins (Fig., 11). These are EW trending moderately folded structures, built up of the

thick Paleogene turbidites and predominantly basaltic volcanics of interarc type

(Lordkipanidze, 1986; Lordkipanidze et al.,1988). The Campanian-Maastrichtian

turbidites and low- Ti high-K shoshonitic basalts of Southern Adjara-Trialeti may be

indicative of the Late Cretaceous supra-subductional rifting events.

The Burgas Late Cretaceous shoshonitic-turbiditic trough in the north-

easternmost part of the Srednagora, Late Cretaceous arc extends into the deep

marine trough of the Western Black sea. Directly North the Burgas rift is bordered by

the EW trending, westward outwedging Campanian-Middle Eocene turbiditic trough of

164

the Luda-Kamchia zone with local manifestations of the Paleogene arc type volcanism

(Dabovski et al., 1989). The Middle-Late Cretaceous to Paleogene opening of the

Black Sea, related to interarc rifting has been suggested (Adamia et al., 1974, 1977,

1989; Lordkipanidze et al, 1979, 1984; Le Pichon, 1984). The recent paleomagnetic

evidence (Channel et al, 1994, 1996)) pointing to a considerable southward

displacement of Pontides in the Late Jurassic-Late Cretaceous time span (from 38.6 N

to 23.8 N) is strongly in favour of the Middle Late Cretaceous opening of the basin. But

it is necessary to stress that the Black Sea evolved dring long time span and was

formed as a result of successive events of the back-arc rifting within the Paleozoic-

Mesozoic-Cenozoic northern active margin of the Tethys ocean. Starting at least from

the Middle Carboniferous in the Black Sea region there existed back-arc basins

behind the Transcaucasian-Pointides volcanic arc system. The system was evolving

from the Paleozoic to Early Cenozoic and experienced numerous rearrangements.

The Kulla Late Cretaceous turbiditic trough of the north-western Balkans and

the Solnok depression of the Inner Carpathians seem to belong to the same chain of

the en-echelon marginal seas.

The last episode of the Black Sea rifting spreading and opening of the West

and East Black Sea back-arc basins occured during Albian-Eocene (Adamia et al.,

1974; Bonchev, 1976). The pattern of magnetic anomalies indicates to diffused

centers of spreading (Mirlin et al., 1972).

Further to the North the Upper Jurassic-Lower Cretaceous turbidites and

Upper Jurassic shoshonitic basalts of the Kura depression (East-Central

Transcaucasus) are interpreted as products of supra-subductional rifting in the

Transcaucasus (Ostroumova and Tsenter, 1987). Upper Jurassic within-plate type

mildly alkaline and tholeiitic basalts (over 2000m) and evaporites (up to 500m) may

result from the transform-bound rifting of the West-Central Transcaucasus in the

back-arc setting (Lordkipanidze et al, 1988). Westward increasing intensity of

volcanism and evaporitic sedimentation allows to extend this structure into the Black

Sea and implies spreading within the latter. Nish-Trojan turbiditic marginal sea of

Eastern Bulgaria (Dabovski et al., 1989) may belong to the same basin. Severin,

Chahleu and Kraina units of the Southern Carpathian seem to be originated in similar

tectonic setting.

The Transcaucasian and the Greater Caucasian arcs are divided by the

isoclinally folded and imbricated unit of the Southern Slope of the Grerater

Caucasus. A detailed structural, stratigraphical, sedimentological studies of this unit

yielded unique evidence of the continuous deep-marine sedimentation from the mid-

Paleozoic up to Early Cenozoic marginal sea basin in the back-arc setting. In the

central part of the Southern slope unit (Svaneti) below the Lower Jurassic black slate-

basaltic sequence the Dizi series occur a thick (2000m) pile of phyllites, black slates,

165

sandstone-argillaceou turbidite. Black chert and rare wedges of marmorized

limestones are also present. Middle-Upper Devonian, Lower-Middle Carboniferous

(the Moscowian stage included), Permian, Triassic-Lowermost Jurassic levels are

documented here by conodonts, corals, foraminifers, Rhaet-Hettangian palinomorphs,

Lower Liassic pollen and spors (Adamia et al., 1990), poorly preserved Upper

Carboniferous fossils are also reported. Subduction-related basaltic to rhyolitic,

tholeiitic and calc-alkaline volcanics occur at the Devonian, Carboniferous-Permian

and Triassic levels (Fig., 19).

In the Lower-Middle Jurassic, the Southern Slope basin was expanding and

widenning, accumulating hemipelagic argillites. It was affected by two pulses of

basaltic volcanism in the Domerian and Aalenian, divided by the period of turbiditic

sedimentation. At both levels, aphyric and porphyric tholeiitic undifferentiated pillow-

basalts alternate with black slates. Subordinated mildly alkali varieties are also

present. The Domerian basalts are within-plate to MORB type without any appreciable

subductional component. The Aalenian basalts bear a clearly distinguishable

subductional signature (Nb, Ti negative anomalies on spidegrams) (Lordkipanidze,

1986; Lordkipanidze et al., 1988).

In the Late Jurassic to Late Eocene the basin accumulated terrigenous and

carbonate turbidites. The Caspian basin with its 25km thick undeformed or very

slightly deformed sedimentary cover may represent the eastern, still not closed part of

this long-living deep marine basin.

Western homologues of the Greater Caucasian volcanic-sedimentary

sequences may be the strongly deformed Upper Triassic-Jurassic sequence of

Southern (Mountaneous) Crimea: slates and turbidites alternate here with volcanics

of the tholeiitic basalt-andesite-dacite-rhyolitic series. Basalts and basaltic andesites

predominate (Lebedinski and Markov, 1965). According to the bulk chemistry (low-Al,

low-K basalts comparatively high in TiO ) and differentiation trends the volcanics are

transitional between arc tholeiites and MORB (Lordkipanidze et al., 1988)

Küre Permian to Triassic turbidites, slates and cherts and subduction-related

dismembered ophiolites in North-Central Pontides, accreted before the Upper

Jurassic may belong to the same basin (Lordkipanidze et al., 1988). The Upper

Jurassic to Upper Eocene terrigene and carbonate turbidites of the Greater Caucasus

and Outer Carpathians also belong to the same system of back-arc basins of the

Northern Tethys. The Kotel zone of the north-eastern Balkans and Machin unit of

Dobrudja may represent short-living (Triassic) parts of the same basins.

Paleozoic assemblages of dismembered ophiolites, related terrigenous,

hemipelagic and pelagic sediments occur as allochtonous tectonic sheets on the

northern slope and in the Forerange unit of the Greater Caucasus. These are

tentatively interpreted as assemblages of the Paleozoic interarc and back-arc basins

166

of the Paleozoic active margin of the Tethys. These tectonic sheets are believed to be

rooted on the southern periphery of the Greater Caucasian Main Range, where

metasediments and metaophiolites occur (Adamia et al., 1987). They are represented

by the Kassar, Boolgen, Laba and Belorechinsk tectonic sheets (peridotites,

amphibolites, gabbro-amphibolites, wedges of eclogite-type rocks, diorite gneisses,

micaschists, marbls, plagiogranitic gneisses). Parental rocks of amphibolites are

predominantly basalts, gabbro and diabases. The greater part of the schists is derived

from volcanoclastic and pellitic sediments. The asemblage belongs to the epidote-

amphibolite facies of andalusite-sillimanite and kyanite-sillimanite types. All the rocks

are strongly tectonized and retrogressed in greenschist facies. By character of Al, Si,

Ti distribution trends, by rare elemental (REE included) signatures the amphibolites

may be attributed to the low-Ti and high-Ti types of the ophiolitic gabbros. Rb/Sr ages

give 284 8 ma. This figure probably dates retrograde recrystallization and

tectonization of the rocks.

167

Figure, 19. Generalised stratigraphic colomn of the Dizi serias, Svaneti, Southern Slope of the Great

Caucasusu (after Adamia et al.,1990).

168

In the Forerange zone of the Greater Caucasus ophiolitic and metaophiolitic tectonic sheets (Marukha and Atsgara nappes) overthrust Silurian-Devonian-Lower Carboniferous volcano-sedimentary parautochthone and are transgressively overlain by Middle-Upper Carboniferous-Permian subareal and shallow marine molasses.

The paraautochthonous asemblage of the Forerange represents volcanic-

sedimentary pile built up of low-Ti, low-K basalt-andesite-dacite-rhyolitic tholeiitic

series with very distinct subductional geochemical signature, alternating with

volcanoclastic and terrigenous turbidites of the Silurian?-Devonian-Carboniferous age.

Up the section they are overlain by boninitic volcanics (high-Mg basalts with spinifex

structure, boninites and high-Mg rhyolites). This assemblage is interpreted as a back-

arc basin (Shavishvili, 1983; Adamia et al., 1987) or as the oceanic island arc (Khain,

1984).

The ophiolites of Marukha nappe represent the most complete section of the

oceanic crust comprising tectonized hartzburgites, gabbroic cummulates, sheeted

dykes, volcanic and sedimentary sequences. By their Ti content and by Si, Al, Ti, P, Zr

distribution trends the cummulates belong to the high-Ti type MORB and back-arc

gabbros. Related volcanics of predominantly basaltic composition answer low-K, high-

Ti undifferentiated tholeiitic series transitional between MOR and the oceanic arc type.

Still REE and isotopic data are lacking and subductional geochemical signature of

these rocks is not very distinct (Adamia et al., 1987).

Sedimentary sequences of the Marukha nappe are metamorphosed in

greenschist facies. They are represented by terrigenous and volcanoclastic rocks of

the Lower Paleozoic?, Sillurian and Devonian age. Increased sedimentation rate and

type of sediments points to their accumulation in a small oceanic basin of back-arc

type.

The metaophiolites of the Atsgara nappe are amphibolites, gabbro-amphibolites

(flaser-gabbro), amphibolitic schists and microgneisses, originated from withinplate

type Fe, Ti, K, P and LIL enriched gabbro, basalts and basic volcanoclastic rocks.

Metagraywakes and metapelites are also present. Metamorphic grade changes from

greenschists to low-T amphibolitic facies. Age of metamorphism is Middle Paleozoic

(Khain, 1984). Thus the parental rocks may be attributed to Early Paleozoic or even

to Precambrian.

Thus the Precambrian - Lower Paleozoic (Atsgara tectonic sheet) to Lower-

Middle Paleozoic (Main Range ophiolites, paraauthochtonous subductional volcano-

sedimentary sequences of the Forerange) are widely spread in the Greater Caucasian

Main Range and Forerange. Some of them manifest more or less distinct subductional

geochemical signature, all of them are tentatively attributed to fore-arc and back-arc

assemblages basing on the nature of related sediments (Adamia et al., 1987).

169

POSTCOLLISIONAL EVENTS

During the Neogene-Quarternary stage of magmatism, two calc-alkaline to

shoshonitic volcanic belts formed in the region. The older, lower-middle Miocene,

volcanic belt of West Anatolia-Balkans has several features of subduction-related

magmatism (high water content of magmatic melts, predominance of intermediate

compositions, high-Al and low-Ti concentrations in the basalts). The extremely high U,

Th, and REE element content and high strontium isotopic ratios indicate intense

contamination by upper crustal material. The break in volcanic activity during the

interval 15.5-12.5 Ma is synchronous with the latest Alpine tectonic event. Subduction

was changed by a tensional event at about 12.5 Ma, when extrusion of anatectic

rhyolites was followed by eruption of high-Ti within-plate type alkaline basalts

(Lordkipanidze et al., 1988).

The younger, E/W-trending Sarmatian-Holocene andesitic belt superimposed

over the late Paleogene molassic depressions seems to be related to remanent

subduction of the Tethyan floor in the southern Anatolia-Zagros zone. The related

volcanics bear a strong resemblance to Andean-type volcanic series. The Van-

Transcaucasian transverse fault zone facilitates the simultaneous ascent of magmatic

melts from subduction-related chambers and from deeper mantle levels. The

geodynamic environment of Greater Caucasus magmatism is controversial.

Geophysical data indicate the existence of a northward-dipping thrust faults beneath

the Greater Caucasus-Crimea. The high water content in the Greater Caucasus

polygenetic acidic, as well as in basaltic melts, and their dominantly calc-alkaline

character are typical of subduction zone magmatism. Large-scale upper crustal

involvement and magma mixing processes are evident from mineralogical as well as

(still scantly) geochemical and isotopic data.

Under conditions of continental collision and strong compression, the ascent of

these hybrid magmas to the surface seems possible only in the Transcaucasian fault

zone. In other parts of the Greater Caucasus, deep-seated granitic plutons may occur

that are similar to the Eocene granites of the Alps.

170

CONCLUSIONS

The Paleozoic- Early Cenozoic history of the Eastern Mediterranean can be

interpreted as an uninterrupted evolution of a Pacific type active margins comprising

island arc- back-arc systems and Andean type volcanic belts (Fig., 20). The Devonian

to Eocene island arc setting is established for the Transcaucasus-Eastern Pontides.

Cambro-Ordovician to Eocene calc-alkaline volcanics and granitoids are present in

Western Pontides. Devonian to Eocene uninterrupted deep-marine sedimentation in

the arc related Dizi basin of Greater Caucasus is strong evidence in favour of the

permanent Paleozoic-Early Cenozoic Tethys. It is to be stresed that throughout the

region the existing paleomagnetic and paleobiogeographical data point to north

Tethyan position of the structural units. No exotic terranes have been established

North of the Lesser Caucasian-North Anatolian-Vardar suture.

The North Tethyan active margin experienced numerous reconstructional events

related to major stages of reorganization of the Tethyan plate kinematics (Zonenshain

et al., 1987). The pre-existing arc-back arc pairs were deformed, disrupted and

partially accreted to the European shelf. Simultaneously new island arc-back arc

systems were born, often incorporating fragments of older active margins. Continental

growth through accretion of the forearc-arc-back arc systems seems to be typical of

the central and eastern (wide) Tethys (Robertson and Dixon, 1984; Adamia et

al.,1990; Bulin, 1991; Robertson et al., 1996)

The suggested correlation within the Caucasian-Pontian-Balkanian-Carpathian

regions is based on established paleogeographical setting of the coeval structural

units but their spatial position on the palinspastic models is always conjectural due to

insufficient paleomagmatic evidence. In addition lack of the up-to-date petrological-

geochemical studies of some older (Lower-Middle Paleozoic) terranes makes

conventional the assumptions on their geodynamic environment.

171

Figure, 20, Paleotectonic reconstructions of the Turkey-Caucasus and adjoining areas of the

Mediterranean (based on global reconstructions by Zonenshain et al.,1987) for Early Permian

(280 Ma), Late Triassic (220 Ma), Early Cretaceous (130 Ma) and Early Paleocene (65 Ma):

1.North Tethyan and Catasiatic terrains (island arcs, microcontinents), 2.South Tethyan

terrains, 3.Subduction, 4.Spreading axes, 5.Oceanic and back-arc basins. S:Scythia, GC:Great

Caucasus, TC:Transcaucasus, NTC:Northern Transcaucasus, STC:Southern Transcaucasus,

SA:Southern Armenia, A:Afganistan, Tb:Tarim, I:Iran, ECI:East Central Iran, T:Turkey,

P:Pontides.

172

REFERENCES

Adamia, Sh.,1974a, Zakariadze, G., Lordkipanidze, M. and Salukvadze, N. Geological

Structure of Ajaria. In Gamkrelidze edit. "Problems of Geology of Ajara-Trialeti".

Tbilisi "Metsniereba, pp. 60-70.

Adamia,Sh., Gamkrelidze,I., Zakariadze,G. and Lordkipanidze,M.,1974b, The Ajaro-

Trialeti Thorough and the Problems of Formation of a Deepwater Basin of the

Black Sea. Geotectonics, 1á, 78-94.

Adamia,Sh., Zakariadze,G., and Lordkipanidze,M.1977a, Evolution of the Ancient Active

Continental Margin, as Illustrated by the Alpine History of the Caucasus:

Geotectonics, 11/4, 299-309.

Adamia,Sh., Lordkipanidze,M., Zakariadze,G.,1977b, Evolution of the Active Continental

Margin as Exemplified by the Alpine History of the Caucasus. Tectonophysics,

(1977), 40 (3/4), 183-199.

Adamia,Sh.,Chkhotua,T.,Kekelia,M.,Lordkipanidze,M.,Shavishvili,I., and Zakariadze,G.,

1981, Tectonics of the Caucasus and Adjoining Regions: Implications for

Evolution of the Tethys Ocean. Struct.Geology, 3, 4, 437-447, London.

Adamia,Sh.,1984, Pre-Alpine Basement of the Caucasus-Composition, Structure and

Formation. Tectonics and Metallogeny of the Caucasus. "Metsniereba", Tbilisi,

pp 3-104,

Adamia,Sh., Belov,A., Kekelia,M., and Shavishvili,I.,1987, Paleozoic Tectonic

Development of the Caucasus and Turkey (Geoitraverse ). In: H.F.Flugel,

F.P.Sassi, P.Grecula (eds). Pre-Variscan and Variscan Events in the Alpine-

Mediterranean Mountain Belt. Alfa Publishers, Bratislava, pp 9-23.

Adamia et al., 1989, Paleotethys, Mesotethys, Neotethys-different oceans or stages of

evolution of Tethys. Proceedings, Geol.Inst.Ac.Sci.Georgia,9, pp.18-49.

Adamia,Sh., Lordkipanidze,M., Kutelia,Z. and Kvantaliani,I.,1990a, Geology of the

Caucasus. Field meetings. Paleogeography and Tectonics of the Paleozoic fold

areas and their platform frame, Tbilisi, 59 p.

Adamia,Sh., Kutelia,Z., Planderova,E.and Khutsishvii,O.,1990b, Rhaetian-Hettangean

Deposits of the Dizi Series of Svaneti (Greater Caucasus). Doklady Acad.Nauk

SSSR, 313, 2, 395-396 (in Russian)

Adamia,Sh., Abesadze,M., Chkhotua,T., Kekelia,M., and Tsimakuridze,G.,1992a,

Tectonites in the Variscan Crystalline Assamblages of the Greater Caucasus and

Dumbier Massif of Western Carpathians. IGCP Proj.276, Paleozoic Geodinamic

Domains and their Alpine Evolution in the Tethys. Dionyz Stur. Inst. Bratislava pp

7-20.

173

Adamia,Sh., Bayraktutan,S., Lordkipadze, M., Kuloshvili,S., Maisuradze,G. and

Chkhotua,T.,1992b, Geology of the Eastern Pontides (Artvin and Erzurum

Districts) Geol.Inst. Ac.Sci.Georgia, 124 p.

Adamia,Sh., Bayraktutan,S. and Lordkipanize,M.,1995, Structural Correlation and

Phanerozoic Evolution of the Caucasus-Eastern Pontides. - Geology of the Black

Sea Region. Ankara, Turkey, pp 69-75.

Aktimur,T., Tekirli,M., Yurdakul,M., Ürgün,B., and Ercan,T.,1992,1/100.000 Ölçekli,

açınsama niletikli Türkiye Jeoloji Haritaları Serisi, Ardahan C-36, Kars-D-36,

Erivan D-37 paftaları: Special publ. of Mineral Research and Expl., No:39, 40, 41,

Ankara,10 p.

Aydın,M., Demir,O., Özçelik,Y. and Terzioğlu,N.,1995, Geological Revision of Inebolu,

Devrekani, Agli and Küre Areas: new Observations in Paleotethys-Neotethys

Sedimentary Succession. Geology of the Black Sea Region, Ankara, Turkey,

pp. 33-38.

Bartinski,Y. and Stepanchuk,L.,1989,Geochronology of granitoides from Phanerozoic

folded areas of the

Eastern Europe. Isotopes in Nature Vth Working Meeting, Laipzig, p.9.

Bektaş,O. and Güven,İ.H.,1995, Alaskan-Appinitic Type Ultra-Mafic and Mafic

Complexes as the root zone of the Eastern Pontides Magmatic Arc (NE Turkey).

Geology of the Black Sea Region. Ankara, Turkey, pp. 189-196.

Belov,A.,1981, Tectonic Development of the Alpine Folded region in Paleozoic.

Transactions, Moscow, Nauka, pp. 347, 212.

Bergougnan,H.,1987, Etudes Geologiques dans l'Est-Anatolien. Mem. Sci. Terre, 86/33.

606.

Bogdanovsky,O.G., Zakariadze,G.S., Karpenko,S.F., Zlobin,S.K., Puchkovskaya,V.M.,

and Amelin,I.V.,1992, Sr-Nd age of gabbros from tholeiitic ophiolite series,

Sevano-Akera Zone (Lesser Caucasus). Abstracts, Ofioliti,, 17(2), 259.

Bonchev,E.,1979, Nature of mobile areas of Balkanides in Phanezozoic and main

moments of its development. In: The tectonic development of the East Crust and

Fractures. Moscow,98-106.

Boulin,J.,1991, Structures in Southwest Asia and Evolution of the Eastern Tethys.

Tectonophysics, 1(6 ), 211-268.

Channell,J.E.T., Bektaş,O., Tüysüz,O., Şengör,A.M.C., Görür,N., Okay,A.J., Yigitibaş,E.,

Sanin,M., Akkök,R., and Pitman,W.C.,1994, Jurassic and Cretaceous

Paleomagnetic Data from the Pontides (Turkey) and Mesozoic Paleogegraphy of

Western Tethys, abstracts of 1994 Spring meeting.

Channell,J.E.T, Tüysüz,O., Bektaş,O., and Şengör,A.M.C., 1996, Jurassic-Cretaceous

174

Paleomagnetism and Paleogeography of the Pontides (Turkey). Tectonics,15, 1,

201-212.

Dabovsky,K., Harkovska,A., Kamenov,B., Marrudchiev,B., Stanisheva-Vassileva,G.,

Chunev,D. and Janev,I.,1989, Map of the Alpine Magmatism in Bulgaria

(Geodynamic Approach), Sofia.

Evans,I. and Hall,S.A.,1990, Paleomagnetic Constraints on the Tectonic Evolution of

the Sakarya Continent, NW Anatolia. Tectonophysics, 182, 357-372.

Evans,I., Hall,S.A., Carman,M.T., Şenalp,M. and Coscun S.,1982, Paleomagnetic Study

of the Bilecik Limestone (Jurassic), NW Anatolia. Earth. Planet.Sci.Lett. 61/1,

199-209,

Hasanov, 1986,History of development of Sevano-Akera ophiolitic zone of the Lesser

Caucasus. Geotectonica, 2, 92-104.

Ivanov,Z.,1988, Apercu General sur l'Evolution Geologique et Structurale du Massif des

Rhodopes dans le Cadre des Balcanides. Bull. Soc.Geol. France, IV/2, 227-240.

Kazmin, B. and Knipper,A.,1987, Volcanics heets as markers of the Mesozoic,Cenozoic

active margin of Euroasia-Reply, Techtonophsics, 141-347.

Kazmin,B.,1989, Collisions and Riftogenesis in the History of the Tethys. Geotectonic,

5, 14-23 (in Russian).

Karamata,S.,1988, The "Diabase-Chert Formation" Some Genetic Aspects. Bull.

Acad.Serbe.Sci. Arts. Nat. 95/28, 1-11,

Karyakin,I. and Aristov.,1990, On the Age and Geological Position of the Exotic Rocks

of the Touragachai Zone (Lesser Caucasus). Doklady Akademii Nauk USSR,

331/5, 1189-1193 (in Russian).

Khain,E.,1984, Ophiolites and Hercinian Nappe Structure of the Forerange of the

Northern Caucasus. Moscow, Geological Institute Memoirs. 238, 96, (in

Russian).

Knipper,A.,1975,Oceanic crust in the structure of the Alpine folded belt. Proceedings,

Geol.Inst.Ac.Sci. USSR, 267,208 p.

Knipper,A.,1990, Pre-Late Jurassic Tectonic Events and Their Role in Formation of

Ophiolitic Sequence in the Caucasus. Symposium on Ophiolite Genesis and

Evolution of Oceanic Lithosphere. Volume of abstracts, Muskat, Oman., p. 112.

Korkmaz,S., Tüysüz,N., Er,M., Musaoğlu,A. and Keskin,I.,1995, Stratigraphy of the

Eastern Pontides, NE Turkey. Geology of the Black Sea Region, Ankara, Turkey,

pp.59-68.

Lebedinski,V. and Markov,N.,1962, Volcanism of Mountainous Crimea. Ac.Sci. Ukrains

Publ.House,Kiev, 168 p.

175

Le Pichon,1984,Trougs of the Mediterranean Sea. In: History and origin of marginal and

Internal seas. Igc. 27th Sess. Symp.06, 2-3. Nauka, Moskow, pp.18-27.

Lordkipanidze,M., Zakariadze,G. and Popolitov,E.,1979, Volcanic Evolution of the

Marginal and Interarc Basins. Tectonophysics, 57, 71-83,

Lordkipanidze,M.,1980, Alpine Volcanism of the Central Segment of the Mediterranean

Belt. Tbilisi "Metsniereba", 162 p.

Lordkipanidze,M., Adamia,Sh. and Asanidze,B.,1984, Evolution of Active Margins of the

Tethys Ocean (Caucasian example) 27.Intern. Geol. Congress.

Palaeoceanography, Coll. 03, 3, 90-104.

Lordkipanidze,M.,1986,Mesozoic-Cenezoic volcanism and geodynamics of the Central

segment of the Alpine-Himalayan felded belt. PhD. Thesis,Tbilisi, 350 p.

Lordkipanidze,M., Meliksetyan,B. And Djarbashian,R.,1988,Mesozoic-Cenozoic

Magmatic Evolution of the Pontian-Crimean-Caucasian Region. Memoirs de la

Soc.Geol. France, Nouvelle Serie. 1988, 154(11), 103-124.

Magakyan,P.,Zakariadze,G.,Dimitriev,L.,Kolesov and Korovkina,M.,1985,Geochemistry

of Jurassic-Lower Cretaceous Volcanic Complex of North Armenia. Volcanology

and Lithology. 3,39-53 (in Russian).

Meliksetyan,B., Bagdasaryan,G. And Gukassyan,P.,1984, Isotopic, Geochemical and

Geochronological Investigation of Eclogite-Amphibolites Associated with

Ophiolites of Sevan-Akeran Belt (Amassia Massif). Izvestia Acad. Nauk.

Arm.SSR. Earth Sci. 37(1), 3-22 (in Russian).

Meschede,M. A.,1986, Method of Discriminating Between Different Types of Mid-Ocean

Ridge Basalts and Continental Tholeiites with the Nb-Zn-Y Diagram.

Chem.Geol., 56, 207-218.

Ostroumova,A. and Tsenter,I.,1987, Analogs of the Marianite-Boninitic Series in the

Jurassic Volcanics of Karabakh Range (Lesser Caucasus). Reports Acad.Sci.

USSR, 290, 441-445 (in Russian).

Peccerillo,A. and Taylor,S.,1976, Geochemistry of Eocene Calc-Alkaline Volcanic Rocks

from the Kastamonu area, Northern Turkey.-Contr. Mineral Petrol.,58, 63-81.

Pickett,E.A., Robertson,A.H.F. and Dixon,J.E.,1995,The Karakaya Complex, NW

Turkey: a Paleo-Tethyan Accretionary Complex. Geology of the Black Sea

Region. Ankara, Turkey, pp. 11-18.

Pithonak,P. And Spisiak,J.,1988, Mineralogia, petrologia a geochemia zakladnych

horninovych typov sirsej ollasti Jasenia-Kysla (Zaverencha sprava). M.S.

Jeofond, Banska Bystrica, Slovakia, p.232.

Robertson,A.H.F. and Dixson, J.E., 1984, Introduction: Aspects of the geological

evolution of the Eastern Mediterranean. In Dixon,J.E. and Robertson A.H.F.

(eds.). The geological evolution of the Eastern Mediterranean. Geol.Soc.London,

176

Spec.Publ., 17, pp.1-74.

Robertson,A.H.F., Cliff,P., Dengan,P., Jones and G.,1991, Paleogeographic and

Paleotectonic Evolution of the Eastern Mediterranean Neotethys.

Paleogeography, Paleoclimatology. Paleoecology. 87, 289-343.

Robertson,A.H.F., Dixon,J.E., Brown,S., Collins,A., Morris,A., Pickett,E., Sharp,I. and

Ustaömer,T.,1996, Alternative Tectonic Models for the Late Paleozoic - Early

Tertiary Development of the Tethys in the Eastern Mediterranean Region. -

"Paleomagnetism and Tectonism of the Mediterranean Region." Geological Soc.

Spec. Publication, 105, 239-263.

Rubinstein,M.M.,1970, Regional und Lokalal Verjungung des Argon-Alters am Beispeil

des Caucasus. Eclogae Geol.Helv.,63, 282-289.

Sarıbudak, M., Şanver,M. and Ponat,E.,1989,Location of Western Pontides NW Turkey

during Triassic Time: Preliminary Paleomagnetic Results. Geophys, J.Int. 96, 43-

50.

Şengör,A.M.C., Yılmaz,Y. and Sungurlu,O.,1985, Tectonics of the Mediterranean

Cimmerides: Nature and Evolution of the Western Termination of Paleo-Tethys:

In Dixon,J.E. and Robertson,A.M.F. (eds). The Geological Evolution of the

Eastern Mediterranean, Spec.Publ.Geol.Soc. 1 F Blackwell. Oxford, 77-11.

Şengün,M.,1995, Structural Features of Elekdağ Ophiolite: Central Pontides - Turkey.

Geology of the Black Sea Region. Ankara, Turkey, pp.39-44

Şengün,M.,1995, Post-Liassic Sedimentary Wedge of Pontides and Its Implications on

the Evolution of the Black Sea. Geology of the Black Sea Region. Ankara,

Turkey, pp.54-58.

Shavishvili,I.,1983, Variscan volcanism of the Caucasus. IGCP, Project N5, Newsletter

5, 12-21.

Sokolov,S.,1974,Tectonical melange of Amassia district (Lesser Caucasus).

Geotectonica, 4, 69-77.

Sokolov,S.,1977, Olistostromes and ophiolitic nappes of the Lesser Caucasus.

Proceedings, Geol.Inst.Ac.Sci.USSR, Moscow, No.296, 94 p.

Tekeli,O.,1981, Subduction Complex of Pre-Jurassic Age, Northern Anatolia, Turkey.

Geology, 9, 68-72.

Tokel,S.,1995, Magmatic and Geochemical Evolution of the Pontide Segment of the

Northern Tethys Subduction System. Geology of the Black Sea Region. Ankara,

Turkey, pp.163-170.

Tunoğlu,C. and Batman,B.,1995, Tectonic Evolution of Devrekani Basin (Kastamonu).

Geology of the Black Sea Region. Ankara, Turkey, pp.45-53

Ustaömer,T. and Robertson,A.M.F. ,1992, Pre-Late Jurassic Tectonic Evolution of the

177

Central Pontides. International Symposium, the Geology of the Black Sea

Region. Ankara, Turkey, Abstracts, p. 13.

Ustaömer,T. and Robertson,A.M.F.,1995, Paleotethyan Tectonic Evolution of the North

Margin in the Central Pontides, N. Turkey. Geology of the Black Sea Region,

Ankara, Turkey, pp.24-32

Yılmaz,A., Adamia,Sh., Lordkipanidze,M., Gugushvili,V., Lazarashvili,T.,Beradze,R.,

Nadareishvili,G., Kuloshvili,S., Salukvadze, N.,Konak,N., Yılmaz,T., Kurt,I.,

Özkan,M., Güven,I.H. and Hakyemez,H.,1996, A study of tectonic unites of the

area along Turkish-Georgian border. 2nd Intern.Symposium on the petroleum

geology and hidrocarbon potential of the Black Sea area.Turkey, Istanbul (Şile),

p.6.

Yılmaz,O., and Boztuğ,D.,1989,The Kastamonu Granitoid Belt of the Northern Turkey:

First Arc Product Related to Paleotethys. Geology, 14,179-183,

Yılmaz,Y. and Şengör,A.M.C.,1985, Paleotethyan Ophiolites in Northern Turkey. Ofioliti,

10 (2/3), 485-504,

Zakariadze,G., Knipper,A., Sobolev,A., Tsamerian,O., and Kolesov,G.,1983, The

Ophiolite Volcanic Series of the Lesser Caucasus. Ofioliti 8(3), 439-466.

Zakariadze,G., Karpenko,S., Bogdanovsky,O., Silantiev,S., Lyalikov,A. and Kozlov,G.,

1988, Nd and Sr isotops and REE Geochemistry in Metamorphic Rocks

Associated with Mesozoic Ophiolites of the Sevan-Akera Zone. Lesser

Caucasus. Ofioliti 13(2/3),137-156.

Zakariadze,G.,Adamia,Sh.,Kolcheva,C.,Jeliazcova-

Panaiotova,M.D.,Danjushevskii,L.V.,Soloviva,H.V., Kolesov,G.M. and

Minin,D.A.,1993, Geochemistry of Metabasic Series of the Pre-Alpine Ophiolites

of the Eastern Mediterranean (Transcaucasian and Rhodopian Massif).

Petrologia,1, 1, 50-87 (in Russian).

Zakariadze G., Knipper A., Sobolev A., Tsamerian O., Dmitriev L., Vishnevskaya B., and

Kolesov G.1986,Peculiarities of Structural Conditions and Content of Volcanic

Series of Ophiolites of Lesser Caucasus. Coll.of Articles: Peculiarities of

Magmatism. Moscow, Nauka, pp. 218-241 (in Russian).

Zlobin,S. and Zakariadze,G.,1986, Geochemical features of island arc plutonic

complexes and their paleoanalogs. Geochem.International, 223, 23-33.

Zonenshain L.P. and Le Pichon X.1986, Deep Basins of the Black Sea and the Caspian

Sea as Remnants of Mesozoic Back-Arc Basins. Tectonophysics, 123, 181-211.

Zonenshain,L., Kazmin,M. and Kononov,M.,1987,Absolute Reconstructions of the

Continent Position in the Paleozoic and Mesozoic. Geotectonica, 3, 16-18 (in

Russian).