Late palaeozoic to cenozoic evolution of the Black SeaSouthern Eastern Europe region: A view from the Russian platform

A synthesis of the Late Palaeozoic to Cenozoic evolution of the Black Sea region and the southern parts of the East European Platform (EEP) is presented. During Carboniferous to Early Permian times the Cordillera-type Euxinus Orogen evolved along the southern margin of the EEP in response to progressive closure of the Rheic and Palaeotethys oceans and the accretion of Gondwana-derived continental terranes.

Late Palaeozoic to Cenozoic Evolution of the Black

Sea-Southern Eastern Europe Region:

A View from the Russian Platform

ANATOLY M NIKISHIN1, PETER A ZIEGLER2,SERGEY N BOLOTOV1 & PAVEL A FOKIN1

1

Geological Faculty, Moscow State University, Vorobyevy Gory, 119991 Moscow, Russia

(E-mail: nikishin@geol.msu.ru) 2

Geological-Palaeontological Institute, University Basel, Bernoullistr 32, 4065 Basel, Switzerland

Received 21 May 2010; revised typescript receipt 13 January 2011; accepted 15 February 2011

Abstract: A synthesis of the Late Palaeozoic to Cenozoic evolution of the Black Sea region and the southern parts

of the East European Platform (EEP) is presented During Carboniferous to Early Permian times the Cordillera-type Euxinus Orogen evolved along the southern margin of the EEP in response to progressive closure of the Rheic and Palaeotethys oceans and the accretion of Gondwana-derived continental terranes Permian development of the north-

dipping Palaeotethys subduction system along the southern Pontides margin of these terranes was accompanied by important compressional intraplate deformation on the EEP Th e Mesozoic to Palaeogene evolution of the southern parts of the EEP, was goverened by closure of Palaeotethys, accretion of the Gondwana-derived Cimmerian terrane and gradual closure of the Neotethys, involving repeated opening and closure of back-arc basins Five discrete tectonic subduction-related cycles are recognized, each commencing with back-arc extension and terminated with back-arc compression Th e timing of these cycles is: (1) latest Permian to Hettangian, (2) Sinemurian to early Callovian, (3) late Callovian to Berriasian, (4) Valanginian to Paleocene and (5) Eocene to Recent Th e duration of the individual cycles was of the order of 30–50 My During back-arc extension, rift ed basins developed along the southern margin of the EEP whilst during back-arc compression compressional stresses were exerted on it, albeit at varying levels during the diff erent tectonic cycles On the EEP, Late Palaeozoic, Mesozoic and Cenozoic intraplate tectonics are expressed by such phenomena as rift ing, extrusion of plateau basalts, inversion of pre-existing tensional basins, gentle lithospheric folding, regional uplift and subsidence

Key Words: East European Platform, Black Sea, Caucasus, Turkey, geological evolution, dynamics, subduction, rift ing,

intraplate tectonics

Karadeniz ve Güneydoğu Avrupa’nın Geç Paleozoyik–Tersiyer Evrimi:

Rus Platformu’ndan Bir BakışÖzet: Bu çalışmada Karadeniz bölgesi ve Doğu Avrupa Platformu’nun (EEP) güney kesiminin Geç Paleozoyik–Tersiyer

evrimi ile ilgili bir sentez sunulmuştur Karbonifer ve Erken Permiyen’de EEP’nin güney kenarında Reik ve Paleotetis okyanuslarının kapanmasına ve Gondwana’dan gelen parçaların Avrasya’ya eklenmesine bağlı olarak Kordillera tipi Öksenus orojeni gelişmiştir Permiyen’de Paleotetis’in Pontidlerin güney kenarı boyunca kuzeye doğru dalmasına bağlı olarak EEP içinde önemli levha-içi skışmalı deformasyonlar meydana gelmiştir EEP’nin güney kenarının Mesozoyik

ve Paleojen evrimi Paleotetis’in kapanması, Gondwana kökenli Kimmeriyen kıtasının Avrasya’ya eklenmesi, Neotetis’in tedrici olarak kapanması ve yay-ardı havzaların açılması ve kapanması ile denetlenmiştir Bu dönemde beş tane dalma-

batma ile ilgili, yay-ardı genişleme ile başlayan ve yay-ardı sıkışma ile biten çevrim tanımlanmıştır Bunlar: (1) en Geç Permiyen–Hettanjiyen, (2) Sinemuriyen–erken Kalloviyen, (3) Geç Kalloviyen–Berriaziyen, (4) Valanjiniyen–Paleosen, (5) Eosen–günümüz Bu çevrimlerin süresi 30–50 milyon sene mertebesindedir Yay-ardı genişleme sırasında EEP’nin güney kenarı boyunca rift havzaları açılmış, yay-ardı sıkışma sırasında EEP’nin güney kenarı değişik derecelerde sıkışma tektoniğine maruz kalmıştır EEP’deki Geç Paleozoyik, Mesozoyik ve Tersiyer levha-içi tektoniği, rift leşme, plato bazaltlarının çıkışı, genişlemeli havzaların inversiyonu, yumuşak litosferik kıvrımlanma, rejyonal yükselme ve çökme ile karakterize olur.

Anahtar Sözcükler: Doğu Avrupa Platformu, Karadeniz, Kafk asya, Türkiye, jeolojik evrim, dinamiks, dalma-batma,

rift leşme, levha içi tektoniği

Whereas the Mesozoic and Cenozoic evolution of

basins occurring on the Peri-Tethyan shelves of

Western and Central Europe is well documented

(Ziegler 1989, 1990; Dercourt et al 1993, 2000; Golonka

2000, 2004; Stampfl i et al 2001a, b), little information

has so far been published on the Peri-Tethyan basins

of Eastern Europe However, Russian geologists have

assembled a large database in collaboration with

colleagues from countries surrounding the Black Sea,

partly within the framework of such international

projects as EUROPROBE, PeriTethys, IGCP-369, ILP,

MEBE, DARIUS (see Dercourt et al 2000; Stampfl i

et al 2001a, b; Gee & Stephenson 2006; Barrier &

Vrielynck 2008)

In this paper we summarize the palaeogeographic

and palaeotectonic evolution of the southern part of

the East-European Platform (EEP) and discuss the

potential relationship between observed intraplate

deformations and the development of the Tethyan

belt, drawing on recent compilations and syntheses

(Nikishin et al 1996, 1997, 1998a, b, 1999, 2000,

2001, 2002, 2003, 2005, 2008, 2010; Ziegler et al

2001; Stephenson et al 2001; Golonka 2004; Moix

et al 2008; Okay et al 2008; Robertson & Ustaömer

2009; Kalvoda & Babek 2010)

Th e area addressed includes the Precambrian

East-European Craton (EEC), the Late Palaeozoic

Scythian Orogen and the Uralian domain which

fringe it to the south and east, respectively, and the

Mesozoic to recent orogenic systems of the

Balkan-Black Sea-Scythian-Caucasus region (Figures

1–3) Th e palaeotectonic and palaeogeographic

restorations of this area presented in this paper are

based on a compilation of all available geological

and geophysical data Th ese maps form the base

for assessing the relationship between intraplate

deformations observed on the EEP and changes

in plate boundary conditions in the Tethyan and

Uralian belts

Th e EEC and the Scythian Platform formed

together the EEP During Late Palaeozoic times the

EEC was bordered, in recent coordinates, to the

southwest by the Variscan Orogen, to the south by

the Euxinus Orogen (new name, see below), and to

the east by the Uralian Orogen, all of which were

tectonically active Th e EEC was bounded to the

west and northwest by the Arctic-North Atlantic Caledonides, and to the northeast by the Baikalian Timan-Pechora-Eastern Barents Sea Province (or Timanides) During Mesozoic and Cenozoic times, the evolution of the western and northern margins of the EEP was mainly controlled by processes related

to the opening of the Arctic-North Atlantic Ocean, whereas development of its southern margin was controlled by processes governing the evolution of the Tethyan system

Late Palaeozoic Euxinus Orogen

Th e Early Permian setting of the EEC and the orogenic system, which was active along its southern margin during Carboniferous to Permian times,

is summarized in Figure 4 Th is orogenic system, which extended from the Rhodope-Moesia area into the Caucasus-Turan area, parts of which are exposed

in areas fl anking the Black Sea, is here termed the Euxinus Orogen, referring to ‘Pontus Euxinus’, the

ancient Greek name for the Black Sea (Nikishin et al

2005)

Th e Euxinus Orogen, similar to the Variscan Orogen forming its western prolongation, contains

a number of Gondwana-derived continental terranes

(e.g., Belov 1981; Ziegler 1989, 1990; Dercourt et al

1993, 2000; Robinson 1997; Pharaoh 1999; Golonka

2000; Yanev 2000; Nikishin et al 2001; Stampfl i et al 2001a, b; Vaida et al 2005; Zakariadze et al 2007; Moix et al 2008; Kalvoda & Babek 2010) However,

unlike the Himalaya-type continent-to-continent collisional western parts of the Variscan Orogen, the Euxinus Orogen remained in Late Palaeozoic times in an Andean-type continent-ocean collisional

setting (Ziegler 1989; Stampfl i et al 2001a, b; Ziegler

& Stampfl i 2001) Th e evolution of Euxinus orogenic system was governed by subduction of the Rheic Ocean and the accretion of Gondwana-derived continental fragments to the southern margin of Baltica Th is subduction system was apparently activated in Ordovician times, controlling the accretion of such terranes as Eastern Avalonia, Armorica and Moravo-Silesia to Baltica during the Caledonian orogeny (Ziegler 1989; Pharaoh 1999; Cocks & Torsvik 2006) During the Devonian, intermittent cycles of back-arc extension and compression controlled the opening of the oceanic

Rheno-Hercynian Basin in the Varsican domain and

the evolution of the

Dniepr-Donbass-Karpinsky-Peri-Caspian rift system on the southern parts of the

EEC, as well as the accretion of additional continental

terranes, such as the Aquitaine-Cantabrian block, to

the Variscan domain In the Variscan, as well as in the

Euxinus system, orogenic activity sharply increased

during Late Visean times Crustal shortening

terminated in the Variscan Orogen at the end of the

Westphalian whereas orogenic activity persisted in the Euxinus Orogen until the Early Permian (Ziegler

1989, 1990; Tait et al 1997; Nikishin et al 2001, 2005;

Stampfl i & Borel 2004)

Unlike the northern parts of the Variscan Orogen, and even more than its southern parts, the Euxinus Orogen was severely disrupted during Mesozoic and Cenozoic times by repeated phases of back-arc rift ing

U R A L S

Medveditsa

Don- Yaly

Konka-Talysh

Volga

Ural

Sev Dvina

Warsaw Minsk Riga St.Petersburg

Perm'

Orenburg Kazan'

Volgograd Moscow

Adzva

Varandey-Kola System

Ladoga Bothnic system

N Danish

Oslo

Dniepr

Dobr ogea

Ac hara -Trialet Sevan-Orduba d

0

Figure 1 Index map of East European Platform, showing main rift ed basis Coloured zones denote highly inverted rift s and

back-arc basins.

T H IA

T rek-Caspian Basin

Indol-Kuban Basin

N . s

p

o

o f G r a C a c

s u s

S.Crimea

Odessa shelf

o s

ore

de ep

Andrusov

Ridge

T apse Basin

WESTERN BLACK SEA BASIN

EASTERN

BLACK

SEABASIN

e

ur

K ar ab h

Strandzha

Centr Pontides al

faults and faulted scarps

ARABIAN PLATE

AFRICAN PLATE

TET SIDES ACCRETIONAL-COLLISIONAL

BEL

T (Mz-Q) Y

Mesozoic oceanic lithosphere

Precambrian continental lithosphere

Precambrian continental lithosphere

Mz-Eo inverted backarc basin

K 2 backarc basin

Triassic accretion

ophiolites

EURASIAN PLATE

Lithosphere of Precaspian region

Cretaceous volcanic belt

1

2

3 3

2

PRECAMBRIAN & PALAEOZOIC CRUST MESOZOIC & CENOZOIC DEFORMATIONS

+

Figure 3 Main crustal units of the Black Sea-Caspian region 1– Mesozoic to Paleocene subduction zone, 2– Recent subduction zone,

3– thrust belt with detached subducted slabs (modifi ed aft er Nikishin et al 2005).

and was overprinted by multiple orogenic pulses

(Nikishin et al 2001, 2005) Th is renders it diffi cult

to reconstruct its architecture and to correlate its

now dispersed components In the following we

review the diff erent elements of Euxinus Orogen and

the characteristics of allochthonous terranes they

include

Dobrogea Orogen

Th e Dobrogea Orogen forms the suture between

the EEC and the Late Precambrian Moesian

micro-continent (Figure 2) and consists of Upper

Ordovician to Devonian accretionary complexes

and Carboniferous to Early Permian marine to

continental molasse-type sediments (Carapelit Formation) Th e main folding phase occurred probably during the Visean, prior to the deposition

of the Carapelit formation (Kruglov & Tsypko 1988;

Sandulescu et al 1995; Pharaoh 1999) Th e Carapelit Formation was intruded by Upper Carboniferous–

Permian granitoids (Sandulescu et al 1995; Seghedi 2009; Balintoni et al 2010) In the Pre-Dobrogea

Depression, corresponding to the northern foreland basin of the Dobrogea Orogen, Upper Carboniferous and older EEC passive margin sequences are overlain

by synorogenic Upper Visean–Serpukhovian coloured, coal-bearing lower molasse series, derived from the rising orogen to the south Th ese grade upward into Stephanian to Permian red-coloured

grey-continental clastics, which contain Lower Permian

(?) volcanics, ranging from basalts to andesites and

rhyolites to ignimbrites (Belov et al 1987, 1990;

Kruglov & Tsypko 1988)

During the Visean docking of the Moesian

Platform against the southern margin of the EEC the

Dobrogea Orogen underwent its main deformation

phase (Yanev 2000) Subsequently, Dobrogea was

repeatedly aff ected by compressional events until

Early Permian times; however, the timing and scope

of these late phases of the Dobrogea orogeny are still poorly constrained

Moesian Terrane

Th e Moesian terrane, which is located southward adjacent to the Dobrogea Orogen (Figure 2), is characterized by a Upper Precambrian Panafrican basement that is covered by an up to 10 km thick, nearly continuous Cambrian to Neogene

I I

evaporites and dolomites

continental sands and shales

hypothetic Devonian oceanic crust

intraplate volcanism

eroded land:

subduction zones

cratonic areas and inactive

foldbelts, low to intermediate relief

active foldbelts, high relief

tectonic symbols:

LEGEND

deeper marine clastics and shales

active thrust fronts

W Pontides

V RISCIDES

deeper marine shales and carbonates

P aspian basin rec

oceanic floor

Precambrian terranes within collisional belts

Donbass

foldbelt

Scythian orogen

Great Caucasus orogen Shatsky

Dzirula

Kura Karabakh

Andrusov

E Pontides Moesia

I A N O O E

I C B E

sedimentary sequence (Tari et al 1997; Yanev

2000; Vaida et al 2005; Seghedi 2009; Kalvoda &

Babek 2010) Th e Gondwana affi nity of this

micro-continent is evidenced by the faunal content of

its Cambro–Ordovician series, as well as by the

occurrence of Upper Ordovician glacio-marine

deposits Th e Moesian terrane was probably detached

from Gondwana at the end of the Ordovician, was

transferred across the Palaeotethys and began to

collide with the Rheic arc-trench system at the

transition from the Devonian to the Carboniferous

During its accretion to the EEC, the Moesian Platform

was subjected to repeated compressional events until

Middle Permian times (Yanev 2000)

Balkan Terrane

Th e Balkan Terrane is located southward adjacent

to the Moesian Terrane and is characterized by

deformed Ordovician to Upper Carboniferous

sediments (Figure 2) As Ordovician to Devonian

series of the Balkan Terrane diff er from those of the

Moesian Platform, Yanev (2000) suggested that it

represents a separate entity that probably collided

during the Early Carboniferous (intra-Visean Sudetic

event) with the Moesian terrane Subsequently

both terranes underwent further compressional

deformation until mid-Permian times

Rhodope Terrane

Th e Rhodope or Rhodope-Th racian Terrane is located

to the south and southwest of the Balkan Terrane

(Figure 2) and is characterized by a very complex

pre-Mesozoic structure Yanev (2000) shows that its

basement consists of a Precambrian (?) and a Variscan

metamorphic complex, which underwent polyphase

orogenic deformation Th e Palaeozoic sedimentary

record of the Rhodope Terrane is poorly constrained

(Moix et al 2008) However, the occurrence of

granitoids, ranging in age between 340 Ma and 320

Ma, indicates that during Carboniferous times it was

aff ected by major orogenic activity Th is suggests

that during the Late Palaeozoic the Rhodope and

Balkan terranes were incorporated, into the branch

of the Euxinus Orogen, which fringed the Moesian

Platform to the south (Ziegler 1989; Stampfl i et al

2001a, b)

Western Pontides

Th e Western Pontides or İstanbul Terrane, located

in northwestern Turkey (Figure 2), probably formed during pre-Cretaceous times the eastern prolongation

of the Moesian Terrane (Okay et al 1994) Similarly

to the latter, the basement of the Western Pontides Terrane was consolidated during the Panafrican

Orogeny (Okay et al 2008) Moreover, the Palaeozoic

sedimentary sequences of both terranes show

considerable similarities (Okay et al 1994, 2008; Şengör 1995; Yılmaz et al 1997; Kozur & Stampfl i

2000; Kalvoda & Babek 2010) Th e İstanbul Zone

of the Western Pontides is characterized by a nearly complete Lower Ordovician to Upper Carboniferous sedimentary sequence, which was deformed during the Hercynian Orogeny (Okay & Tüysüz 1999;

Okay et al 2008) Visean pelagic sediments, grading

laterally into shallow water carbonates, are overlain

by Visean to Bashkirian fl ysch and shales and grade upwards into Upper Carboniferous coal-bearing

series (Kozur & Stampfl i 2000; Okay et al 2006,

2008) Th is suggests that the İstanbul Zone formed part of a Carboniferous foreland basin that was associated with the eastern prolongation Rhodope-Balkan branch of the Euxinus Orogen

Eastern Pontides and Sakarya Terrane

Southward adjacent to the İstanbul Terrane, and separated from it by the Intra-Pontide suture, lies the Hercynian-deformed Sakarya Terrane which extends eastward over a distance of some 1500 km into the Eastern Pontides (Figure 2) Its basement consists

of Precambrian (?) to Palaeozoic metamorphic rocks that were intruded by Devonian and Early Carboniferous to Early Permian granitoids (Okay

Permian (?) shallow marine to continental, type sediments unconformably overlay this basement complex (Okay & Şahintürk 1997; Okay 2000; Okay

molasse-et al 2008).

Great Caucasus Orogen

Th e Palaeozoic basement exposed in the central parts

of Great Caucasus (Figures 2 & 4), can be subdivided into the following units (Letavin 1980, 1987; Belov 1981; Somin 2007, 2009): (1) a Palaeozoic

metamorphic sequence that is intruded by Palaeozoic

granitoids; (2) Upper Palaeozoic, mainly deep-marine

sediments containing intersliced ophiolites and

arc-related volcanics; (3) a Middle to Upper Devonian

subduction-related magmatic island arc complex of

unknown subduction polarity Isotopic zircon data

(Somin 2007, 2009) document exclusively Palaeozoic

ages (±460, 450–280 My) for these metamorphic,

intrusive, volcanic and sedimentary rocks

According to stratigraphic and structural data,

a main phase of folding and large-scale thrusting

occurred during the early(?) Visean (Belov 1981)

Upper Visean strata are mainly developed in a

continental molasse-type facies Th e Middle to Upper

Carboniferous is represented by coal-bearing grey

clastics containing andesites, rhyolites and basalts

Lower Permian continental red-beds contain fl ows of

andesites, dacites and trachytes Th e Upper Permian

is partly represented by shallow-marine sediments

During Middle Carboniferous to Early Permian

times the setting of the Great Caucasus segment of

the Euxinus Orogen was probably akin to an

Andean-type magmatic belt (Mossakovsky 1975; Somin 2007,

2009) Th ere are considerable similarities between

the basement of the Great Caucasus and the Eastern

Pontides

Pre-Caucasus or Scythian Orogen

In the Pre-Caucasus area, located to the north of

the Great Caucasus, the Palaeozoic and older(?)

basement is concealed by Mesozoic and Cenozoic

sediments (Figures 2 & 3) Th us, its evolution is only

constrained by subsurface data Numerous deep

wells penetrated below Mesozoic sediments highly

folded, thrusted and regionally up to greenshist facies

metamorphosed Palaeozoic black shales, cherty

shales, chloritic shales, phyllites and silty shales

that contain rare carbonates (Letavin 1980, 1987;

Belov 1981) Limited palaeontological data give Late

Devonian–Early Carboniferous ages, and in a few

cases possible Early Palaeozoic to Middle Devonian

ages In some zones, possibly corresponding to a

volcanic arc or a rift , andesitic and basaltic volcanics

were encountered (Belov 1981) Th e main phase of

folding, thrusting and uplift occurred during late

Visean–Serpukhovian times (Letavin 1987) Th e

pre-Caucasus segment of the Euxinus Orogen, also

referred to as the Scythian Orogen, was intruded

by many Carboniferous–Lower Permian granitoids (Letavin 1980, 1987; Belov 1981) During Middle

to Late Carboniferous and Permian times, some minor molasse-type basins developed within the pre-Caucasus segment of the Scythian Orogen (Belov

1981) Although Kostyuchenko et al (2004) and Chalot-Prat et al (2007) argue for a Precambrian age

of the Scythian Orogen, there is no hard data that it contains some Precambrian terranes Nevertheless, our new, still unpublished age determinations

on detrital zircons from Cretaceous to Paleocene turbiditic sandstones of the Great Caucasus yielded numerous ages of ±613 Ma Th is suggests that the Scythian Orogen may indeed contain a

so far unidentifi ed Late Neoproterozoic terrane, comparable to İstanbul and Moesian terranes

Crimea

Also in Crimea, Mesozoic and Cenozoic sediments largely conceal the Palaeozoic and older basement (Figure 2; Muratov 1969; Letavin 1980; Gerasimov

1994; Nikishin et al 2005) Nevertheless, borehole

data permit to defi ne four basement units Th e South Crimean unit is buried beneath the Mesozoic South Crimean Orogen; however, along its northern boundary a metamorphic zone contains remnants of Upper Precambrian(?)–Palaeozoic ophiolites (mainly talc-bearing shales and serpentinites; Muratov 1969; Gerasimov 1994) Th e northward adjacent Simferopol unit consists of a metamorphic, possibly Upper Precambrian complex (Muratov 1969; Kruglov & Tsypko 1988) Further north, the Novoselovskoe unit represents a fold belt, which contains metamorphosed Devonian–Lower Carboniferous deep-marine mudstones and volcanics, including remnants of

a volcanic arc (Muratov 1969; Gerasimov 1994); however the presence of Lower Palaeozoic sediments cannot be excluded (Kruglov & Tsypko 1988)

In the Crimean segment of the Scythian Orogen the main orogenic event, though only poorly constrained, presumably occurred during Visean, pre-Serpukhovian times Lower Jurassic fl ysch, exposed directly to the south of the Simferopol unit, contains in a few places huge olistoliths, the oldest

of which consist of Serpukhovian–lower Bashkirian shallow-water limestones and Upper Permian

bioherms (Muratov 1969; Mazarovich & Mileev

1989a, b) Although the source of these olistoliths

is unknown, Serpukovian development of

shallow-water conditions suggests that by this time the

pre-existing Early Carboniferous deep-water trough had

been closed Th is is compatible with the postulated

Visean main deformation phase of the Crimean

segment of the Scythian Orogen, the most external

unit of which may correspond to the very poorly

controlled Late Palaeozoic Sivash molasse basin

(Letavin 1980)

Unfortunately, available lithological data and

age constraints provide only a fragmentary picture

of evolution of the Palaeozoic Crimean basement

that was severely overprinted by Mesozoic orogenic

activity

Dzirula and Possibly Related Terranes

Th e Dzirula Terrane, which is located in Georgia

just to the south of the Great Caucasus (Figure 2),

is characterized by a Upper Precambrian basement

that yielded isotopic ages in the range of 800–540 Ma

and contains Neoproterozoic (±800 Ma) ophiolites,

as well as by deformed, probably Lower Palaeozoic

sediments (Zakariadze et al 2000, 2007) Th ese

complexes are covered by an up to 1300-m-thick

Visean–Bashkirian volcano-sedimentary sequence

that contains rhyolitic lava fl ows and pyroclastics

Similar to the Great Caucasus, also the Dzirula

Terrane was intruded by Permo–Carboniferous

granitoids, which yielded isotopic ages in the 330–280

Ma range (Zakariadze et al 2000, 2007) Geochemical

data show that the Permo–Carboniferous granitoids

were intruded under a supra-subduction setting

(Zakariadze et al 2000, 2007).

With its Panafrican–Upper Neoproterozoic

basement, the Dzirula Terrane was probably derived

from Gondwana and was accreted during the Early

Carboniferous to the southern Great Caucasus

segment of the Euxinus Orogen Th is is compatible

with the occurrence of subduction-related K-granites

in the Trans-Great Caucasus area, which yielded ages

in the range of 330–280 Ma (Zakariadze et al 2007;

Nikishin et al 2001).

Th e basement of the Karabakh Terrane (Figure

2), which is located to the southeast of the Dzirula

Terrane, is exposed in small areas only However, as

it is very similar to that of the Dzirula Terrane it may actually form part of it (Milanovsky 1996; Zakariadze

et al 2007).

Th ick Mesozoic and Cenozoic sediments cover the basement of the Shatsky, Kura and Andrusov blocks (Figure 2) Geophysical data indicate that the Shatsky Block forms the off shore prolongation of the Dzirula Terrane No data are available on the pre-Mesozoic of the Kura and Andrusov blocks, which probably also formed part of Precambrian or Palaeozoic terranes prior to the Late Cretaceous to Palaeogene opening

of the Eastern Black Sea

Karpinsky Fold Belt

Th e Karpinsky Swell bounds the pre-Caucasus segment of the Scythian Orogen to the North (Figures

2 & 4) It represents the inverted southeastern part of the Devonian Dniepr-Donbass-Karpinsky rift (Milanovsky 1996; Sobornov 1995; Nikishin

et al 1996, 2001, 2005; Stephenson et al 2001;

Kostyuchenko et al 2004) According to refl

ection-seismic data, the Karpinsky Swell involves a nearly 15–20-km-thick sequence of folded sediments, the

bulk of which is Carboniferous in age (Brodsky et

al 1994; Kostyuchenko et al 2004) However, no

strata older than Bashkirian have been penetrated

by wells (Letavin 1980) Bashkirian–Asselian series consist mainly of claystones, shales and siltstones

An angular unconformity is evident at the base of

the Artinskian molasse (Nikishin et al 2001) Th is indicates that the main deformation phase of the Karpinsky Basin, involving folding and thrusting

of its sedimentary fi ll, occurred in pre-Artinskian times, possibly during the Sakmarian

Wells and refl ection-seismic data from the northern fl ank of the Karpinsky Swell indicate that it was thrust northwards by at least a few tens kilometres over the margin of adjacent peri-Caspian

Basin (Kapustin 1982; Brodsky et al 1994) Well

data from this external Karakul-Smushkovoe thrust belt and its associated foredeep basin show that Tournaisian(?), Visean and lower Serpukhovian series are developed in a relatively shallow-marine carbonate facies and contain bioherms By contrast, upper Serpukhovian–Bashkirian sediments consist

of deep-water cherty carbonates and radiolarites, containing volcanic ash Mainly argillaceous

sediments represent Moscovian and Gzhelian

series, whereas the Asselian is developed in a fl

ysch-type facies (Nikishin et al 2001) Th e rapid late

Serpukhovian–Bashkirian subsidence of the North

Karpinsky zone probably refl ects tectonic loading

of the southern margin of the peri-Caspian Basin by

the evolving Karpinsky-Karakul-Smushkovoe thrust

belt, the main deformation of which occurred during

the Early Permian (Sakmarian), as evidenced by

borehole and seismic data (Kapustin 1982; Brodsky

et al 1994; Volozh et al 1999; Nikishin et al 2001).

From Late Visean times onwards, the evolution

of the Karpinsky Basin was paralleled by orogenic

activity in the Caucasus and pre-Caucasus segment of

the Scythian Orogen During Visean to Asselian times

the Karpinsky Basin was gradually incorporated into

the fl exural foreland basin of the Scythian Orogen

from which clastics were shed into it (Letavin 1987)

Similarly, the Dniepr and Donbass segments of the

Devonian Dniepr-Karpinsky rift experienced during

their Carboniferous post-rift evolution repeated

phases of accelerated subsidence (Nikishin et al 1996;

Stovba et al 1996; van Wees et al 1996) that probably

can be related to the development of the Scythian

Orogen Th is suggests that large fl exural foreland

basins developed during Carboniferous times along

the northern fl ank of the evolving Scythian Orogen,

remnants of which are now only preserved in the

inverted Donbass and Karpinsky Basin

Cordilleran-type Euxinus Orogen

Th e Euxinus Orogen, as summarized in Figure 4,

was characterized by a very complex structure and

included a number of continental Gondwana-derived

allochthonous terranes Th ese terranes formed part

of the composite Hunic Terrane that was detached

from Gondwana during the Late Ordovician–Early

Silurian, components of which were incorporated

into the Euxinus Orogen during Late Devonian to

Carboniferous times in conjunction with progressive

closure of the Rheic Ocean and opening of the

Palaeotethys (Stampfl i et al 2001a, b; Stampfl i &

Borel 2004; Cocks & Torsvik 2006) Within the

Euxinus Orogen well-defi ned allochthonous

continental terranes are the Moesian-West Pontides,

Rhodope, and the Dzirula (Balkan, Eastern Pontides,

Shatsky, Karabakh, Kura - ?) terranes In the Turan

area possible allochthonous continental terranes are the Kara-Bogaz and Usturt blocks (Golonka 2000) Th e Euxinus Orogen contains also Lower Palaeozoic ophiolites (Great Caucasus), Ordovician (?) to Devonian subduction-related accretionary complexes (Dobrogea), Devonian volcanic arcs (Great Caucasus) and Carboniferous to Lower Permian molasse basins and widespread granitic plutons

Th e Early Permian southern margin of the Euxinus Orogen is thought to coincide with the ophiolitic suture which extends from the Vardar zone on the Balkan Peninsula via the İzmir-Ankara-Erzincan zone of Turkey to the Sevan zone of Armenia and Azerbaijan (Robinson 1997; Okay

2000; Stampfl i et al 2001a, b; Nikishin et al 2005)

Continental terranes and fragments of Upper Palaeozoic basement blocks, which are interpreted

as forming part of the Euxinus Orogen owing to their Permo–Carboniferous deformation, are all located to the north of this suture On the other hand, continental terranes located to the south of this suture were not aff ected by Permo–Carboniferous orogenic processes and therefore are attributed to the composite Cimmerian terrane, which was rift ed off the northern margin of Gondwana during Permian times and was accreted to the Euxinus Orogen during the Mesozoic Cimmerian orogenic cycle, involving closure of the Palaeotethys Ocean (e.g., Ziegler 1989;

Dercourt et al 2000; Golonka 2000; Stampfl i et al

2001a, b; Stampfl i & Borel 2004; Cocks & Torsvik 2006)

During the Early Permian the southern margin

of the Euxinus Orogen was associated with the Palaeotethys arc-trench system that fringed the southern margin of the accreted Gondwana-derived Moesia-Rhodope, Pontides and Dzirula terranes Th e tectono-stratigraphic record of the Euxinus Orogen

is, however, too fragmentary to determine the docking age of its diff erent allochthonous terranes and of potential suture sealing overstep sequence Nevertheless, there are indications that the evolution

of this orogen involved multiple deformation phases, going back as far as the Siluro–Ordovician, as evident

in the Great Caucasus Orogenic activity apparently increased sharply during the Early Carboniferous (Late Visean?), presumably in response to closure

of the Rheic oceanic basin and the docking of e.g.,

the Moesia, Balkan, Western Pontides terranes to

the southern EEC margin Th is was accompanied

and followed by rapid subsidence of the Scythian

foreland basin in the

Donbass-Karpinsky-Peri-Caspian domain, of molasse basins in the Caucasus

and Balkan domains and the onset of fl

ysch-type sedimentation in the Western Pontides Late

Carboniferous and Early Permian orogenic phases

controlled the further evolution of these basins and

ultimately the suturing of the accreted terranes to the

southern margin of the EEC Th is is exemplifi ed by

the Early Permian regional compressional event that

caused, amongst others, large-scale thrusting in the

Karpinsky Basin, inversion of the Dniepr-Donbass

rift and fi nal folding of the Dobrogea belt Moreover,

Upper Carboniferous–Lower Permian

subduction-related granitoids occur throughout the Euxinus

Orogen

By Early Permian times, the megatectonic setting

of the Euxinus Orogen was of an Andean

continent-ocean collisional type with the Palaeotethys

subduction zone dipping northward beneath it

(Figure 4) Westward the Euxinus Orogen graded

into the Variscan Orogen, the western parts of which

had entered a Himalaya-type continent-to-continent

collisional stage already during Early Carboniferous

times (Ziegler 1989, 1990; Stampfl i et al 2001a, b;

Cocks & Torsvik 2006) Northeastward the Euxinus

Orogen graded into the Uralian Orogen the southern

parts of which had entered a Himalayan-type

collisional stage during the Late Carboniferous–

Early Permian (Bogdanov & Khain 1981; Milanovsky

1996)

During Sakmarian to Artinskian times the

Euxinus Orogen was regionally uplift ed and subjected

to erosion Its post-orogenic collapse commenced

during the Kungurian–Late Permian (Nikishin et al

1996 2001, 2005; Afanasenkov et al 2008; Murzin

2010)

Triassic to Hettangian Early Cimmerian Tectonic

Cycle

During the Early and Middle Triassic, the area

of the former Euxinus Orogen was aff ected by a

major cycle of back-arc rift ing, resulting in the

opening of the presumably oceanic South

Crimea-Küre-Svanetia Basin (Ustaömer & Robertson 1994;

Nikishin et al 2001, 2005; Stampfl i et al 2001a, b)

At the same time rift ing aff ected Western Siberia and the Urals, the Pechora Basin, the Arctic-North Atlantic domain, the Western Tethys belt as well

as Western Europe (Ziegler et al 2001; Nikishin et

al 2002) Moreover, the Teisseyre-Tornquist line,

which extends from Denmark to the Black Sea and marks the boundary between the Precambrian EEC and the West and Central European domains of Caledonian and Variscan crustal consolidation, was

tensionally reactivated (Ziegler et al 2001; Nikishin

et al 1998b, 2001, 2002) (Figure 5) Whilst elsewhere,

crustal extension persisted to various degrees into Early Jurassic times, the Black Sea domain was aff ected during Carnian to Hettangian times by a major compressional pulse, referred to as the Early Cimmerian Orogeny At the same time a major orogenic pulse aff ected the northernmost Urals and Novaya Zemlya Below we review the Triassic–Early Jurassic evolution of the EEP and its southern and eastern margins

Scythian Platform

On the Scythian Platform, Upper Permian(?), Lower and Middle Triassic sediments are preserved in the East pre-Caucasus area in the East Manych, Kayasula, South Buzachi and Mozdok troughs, and in the West pre-Caucasus-Crimea area in the Northern Crimea-Azov and Novo-Fedorovsk troughs (Figures 5 & 6;

Slavin 1986; Lozovsky 1992; Nikishin et al 1998a,

b, 2001; Dercourt et al 2000) Th e Stavropol High

of the central pre-Caucasus domain separates these areas Further to the west, the extensional system

of the Teisseyre-Tornquist Zone extends from the North Danish Basin through the Polish Trough under the Carpathians and reappears in the Triassic Dobrogea rift (Kutek 2001; Seghedi 2001) On the Scythian Platform, un-metamorphosed Triassic (or Permo–Triassic) sediments rest unconformably on deeply truncated greenshist facies Palaeozoic strata

Th is signifi cant metamorphic step indicates that the Scythian Orogen was deeply eroded during Permian times

Th e stratigraphic and magmatic record of the Scythian Platform indicates that it was compressionally deformed during late Carnian to

Hettangian Early Cimmerian Orogeny with main

deformations occurring during late

Carnian–pre-Norian times, at the Rhaetian/Hettangian transition

and during the Hettangian (Nikishin et al 1998a, b,

2001) Moreover, during the Late Triassic a broad,

E–W-trending calc-alkaline magmatic belt developed

on the Scythian Platform

On the Scythian Platform, Upper Triassic

sediments occur in four main regions, namely in

the Nogaisk Basin of the East pre-Caucasus area, in

the Kuban basins of the West pre-Caucasus area, in

the Karpinsky Basin, and in a system of smaller,

ill-defi ned basins of the Crimean-Azov region (Figures

6 & 7) In these basins, Norian-Rhaetian series rest unconformably on early Carnian and older strata, indicating that these precursor basins were inverted prior to the resumption of sedimentation (Nikishin

et al 2001) So far, Hettangian sediments have not

been identifi ed on the Scythian Platform and appear

to be regionally missing Moreover, a regional unconformity separates Late Triassic from younger strata, with all Triassic basins of the Scythian Platform showing evidence for inversion during the fi nal

pulses of the Early Cimmerian orogeny (Nikishin et

mainy shallow marine

deltaic and coastal

LEGEND

oceanic floor

abbreviations:

K KR NCA NF

Kos’yu-Rogovaya, North Crimea-Azov Novo-Fedorovsk East Manych Trough South Buzachi Pre-Kuma uplift

EMT Sbuz PK

– – – – – – –

PALAEOTETHYS

Donets Basin Dniepr Basin

Moscow Basin

Pechora Basin

P aspian Basin rec

Moesian Platform

Bohemian Massif

Armorican

Massif

N.Sea Basin

Baltic Shield

W.Siberia Rift System

Barents Sea Basin

Mezen Basin

EAST -EUROPEAN CRATON

Kayasula Basin

East-Srednegorie Basin

NCA NF

Stavropol High

S.Crimea-Kure-Svanetia Basin

Figure 5 Early Triassic palaeogeographic/palaeotectonic map of the East-European Platform (modifi ed aft er Nikishin et al 2005)

East Pre-Caucasus Area

For the East pre-Caucasus area reliable stratigraphic

data show that sedimentation resumed during the

Early Triassic under marine conditions and persisted

at least until early Carnian times Rift ed basins were

characterized by deeper-water conditions whereas

intervening unextended areas were occupied by

reef-fringed carbonate platforms (Nikishin et al

1994, 1998a, b, 2001; Dercourt et al 2000) For

instance, in the East Manych Trough, located along

the southern fl ank of the Karpinsky Swell,

shallow-water carbonates grade upwards into deeper-shallow-water

clays, marls and carbonates Subsidence of this

basin was accompanied a mafi cfelsic bimodal rift

-related volcanism (Nikishin et al 1998a, b) Similarly,

sedimentation in the Kayasula Basin was carbonate dominated Th e high, separating the East Manych and Kayasula troughs, was covered by a reef fringed pre-Kuma carbonate platform Preliminary data from the Mozdok Basin indicate the presence of turbiditic sediments, suggesting that this trough may have formed part of an Early to Middle Triassic passive

margin (Nikishin et al 2001) Th e partly inverted South Buzachi Basin in the Northern Caspian Sea area represents the eastern prolongation of the Karpinsky Swell (Figures 6 & 7) Recent drilling data indicate

Moscow

Ukrainian Arch

Berlin

P

lish

rough

Brabant

Massif

N.Sea Basin

Barents Sea Basin

Shatsky

E Pontides

W Pontides

Dzirula

Kura

accreted Iranian terrane

İzmir-Ankara-Sevan ocean

T iman Swell

Moesian Massif

main collision suture

P aspian Basin rec

m

baw e

Medveditsa Swell

Don-Donets Basin Karpinsky Basin

swells and foldbelts, mainly moderate relief

active foldbelts, high relief

deltaic and coastal

clastics

deeper marine, mainly shales

rift basins

intraplate volcanics and volcaniclastics calc-alkaline volcanics

transcurrent faults

continental slope subduction

that the South Buzachi Basins contains

Lower(?)-Middle Triassic shales, siltstones and sandstones,

and Upper Triassic(?) carbonates (Afanasenkov et al

2008; Murzin 2010)

Following late Carnian partial inversion and

erosion of the East Manych-Kayasula-Mozdok

system of basins, the Nogaisk Basin developed on

top of them during the Norian and Rhaetian Th is

basin contains an up to 1.5-km-thick continental

to shallow-marine sequence of silts, sands and

conglomerates that includes a signifi cant amount of

calc-alkaline andesite and rhyolite fl ows, ignimbrites,

tuff s and reworked volcanic rocks (Nikishin et al

2001; Tikhomirov et al 2004) In the southern parts

of this basin, volcanic rocks attain thicknesses of up

to 1.5 km

West Pre-Caucasus – Crimea

Although the biostratigraphic control on Triassic

sediments occurring in the West pre-Caucasus -

Crimean area is less reliable (Nikishin et al 1998a,

b, 2001), it is obvious that the Northern

Crimea-Azov and Novo-Fedorovsk troughs contain Lower

Triassic(?) to lower Norian turbiditic clastics, clays

and carbonates (Figure 5; Slavin 1986; Boiko 1993)

In the Kuban Basin, Early to Middle Triassic series

consist of carbonates and clastics Overall,

palaeo-water depths apparently increased towards the Great

Caucasus area (Boiko 1993) Triassic development

of the South Crimean Trough is indicated by the

accumulation of the thick, though poorly dated

Tavric fl ysch that fi nds its equivalents in the Central

Pontides Küre Basin (Ustaömer & Robertson 1994,

1997; Robinson & Kerusov 1997; Nikishin et al 2001,

2005) and possibly also the Karakaya Zone of Turkey

(Okay et al 1996; Yılmaz et al 1997).

Quantitative subsidence analysis carried out on

selected wells from the East pre-Caucasus area and

Crimea show that both areas subsided rapidly during

the Early and Middle Triassic (Bolotov 1996; Nikishin

of Lower–Middle Triassic basalts and bimodal

volcanics are consistent with intracratonic or

back-arc rift ing However, due to insuffi cient geochemical

data on these volcanic rocks, we cannot discriminate

between these two types of rift ing Moreover, it must

be realized that the outlines of the respective rift s is

poorly known Correspondingly, the Early Triassic palaeogeographic/palaeotectonic reconstruction of the EEP, as given in the Figure 5, must be considered

as tentative

Similarly the Kuban Basin underwent signifi cant structural changes during the Late Triassic (Figure 7) In its diff erent parts, Norian and Rhaetian series consist variably of fl ysch, bioherms and shallow-marine clastics (Boiko 1993; Prutsky & Lavrischev 1989), whilst in the vicinity of the Great Caucasus a reef belt developed (Boiko 1993) In the Crimea-Azov region, Upper Triassic strata are mainly developed in

a fl ysch-type facies in the Novo-Fedorovsk, South Crimea and Azov-North Crimea troughs In these basins, a possible unconformity separates Triassic from Lower Jurassic strata, refl ecting their partial inversion at the transition from the Triassic to the

Jurassic (Slavin 1986; Nikishin et al 2001) In Central

and Northern Crimea, a few wells penetrated poorly dated possibly Upper Triassic dacites, andesites and diorite intrusions (Slavin 1986)

In the Kuban Basin, some wells penetrated beneath Cretaceous strata thick calc-alkaline volcanic sequences of a possible, though not proven, Late Triassic age Upper Triassic volcanics occurring

in the Nogaisk-Kuban-Crimea region indicate that a large calc-alkaline magmatic province had developed

on the Scythian Platform during the early phases

of the Early Cimmerian Orogeny (Khain 1979)

Th ese volcanics were deeply eroded during Jurassic times Although available geochemical data suggest this magmatic activity was subduction related

(Tikhomirov et al 2004), this has to be confi rmed by

additional analyses

On the Odessa Shelf of the Black Sea, just west of Crimea, a deep well penetrated a few hundred metres thick Norian fl ysch-type, sequence containing some tuff horizons and andesitic and rhyolitic volcanicalstics (Ulanovskaya & Shevchenko 1992)

Th is suggests that a more or less continuous Norian volcanic belt extended from the East pre-Caucasus area to the Odessa Shelf and possibly to Dobrogea

Great Caucasus

Th e highly deformed Dizi complex, which outcrops

on the southern slope of the Great Caucasus in

Svanetia (Georgia), consists of a Devonian to Triassic

sediments and volcanics It is commonly assumed

that the Dizi Basin came into existence during the

Devonian and persisted until it was closed at the

Triassic/Jurassic transition (Belov 1981; Kazmin

& Sborschikov 1989; Somin 2007) Devonian–

Carboniferous shales and sandstones, containing

some volcanics and carbonate blocks (olistoliths?),

are unconformably overlain by Permian shales and

sandstones and Triassic clastics Triassic sediments

are in tectonic contact with older ones According

to our interpretation, the Dizi complex represents

a Devonian to Carboniferous accretionary prism

that, upon closure of the Dizi suture, was covered by

Permian marine molasse-type sediments (Nikishin

et al 2001) During the Triassic, this suture was

tensionally reactivated and developed into a rift ed

basin Th e occurrence of Sinemurian sediments,

which rest unconformably on strongly deformed

Triassic series (Belov 1981; Kazmin & Sborschikov

1989; Somin 2007), indicates that the Triassic Dizi rift

was strongly inverted during the Early Cimmerian

orogeny, involving the collision of the Dzirula

Terrane with the Scythian Platform (Figures 7 & 8;

Kazmin & Sborschikov 1989; Nikishin et al 1998b;

Somin 2007)

Dniepr-Donets Basin and Karpinsky Swell

Triassic continental clastics, attaining thicknesses of

up to 500 m in the Dniepr Basin (Figures 1 & 5), and

rest unconformably on Permian and Carboniferous

sediments (Lozovsky 1992; Kabyshev et al 1998;

Dercourt et al 2000) Subsidence analysis show

that the Dniepr-Donets Basin experienced a phase

of accelerated subsidence during the Triassic (van

Wees et al 1996) Although there is no evidence for

syndepositional Triassic extensional faulting, this

subsidence phase may be tensional in origin

Around the Triassic/Jurassic transition, the

Karpinsky Swell was reactivated and thrust over the

southern margin of the Precaspian Basin (Sobornov

1995; Nikishin et al 1998a, b) Th is was paralleled

by a phase of partial inversion of the Donbass Basin

(Figure 8; Stepanov 1944; Stovba & Stephenson 1999;

Stephenson et al 2001; Nikishin et al 2001, 2005).

Teisseyre-Tornquist Zone

Th e Teisseyre-Tornquist Zone (Figures 1 & 5) was reactivated during latest Carboniferous and Early Permian times as a major dextral wrench zone that terminated in the Oslo Graben of Norway (Ziegler

1989, 1990) Superimposed on the Tornquist Zone, the tensional North Danish Basin, the Polish Trough and the Dobrogea Basin (Kutek

Teisseyre-2001; Nikishin et al Teisseyre-2001; Seghedi 2001, 2009)

developed during Late Permian and Triassic times, forming part of a large rift system

Th e Dobrogea Orogen, that experienced a last compressional deformation during Middle Permian

times (Sandulescu et al 1995), was disrupted by

rift ing starting in the Late Permian (Seghedi 2009) Magmatic activity commenced at the same time with the extrusion of felsic and basic volcanics and culminated during the late Early and early Middle Triassic (Spathian to middle Anisian) when E-MORB-type pillow basalts were extruded in the axial parts of

this basin (Sandulescu et al 1995; Nicolae & Seghedi 1996; Seghedi 2001; Stampfl i et al 2001a) Whether

these pillow basalts, which were extruded in a basin characterized by pelagic Hallstatt-facies carbonates, indicating considerable water depths, represent true oceanic crust, is uncertain During the Anisian, the North Dobrogea Basin entered its post-rift stage that lasted till the late Carnian onset of Early Cimmerian

orogeny (Seghedi 2001, 2009; Nikishin et al 2000).

During the late Carnian, compressional deformation of the North Dobrogea Basin commenced, as evidenced by the deposition of

fl ysch-types series, locally resting unconformably on truncated lowest Triassic sediments or the basement

(Seghedi 2001; Nikishin et al 2000) Th is deformation

is taken as a far-fi eld eff ect of the Early Cimmerian Orogeny, which aff ected particularly the southern margin of the Moesian Platform

Moesian Platform

During the earliest Triassic and again during the early Carnian–early Norian the southern parts of the Moesian Platform were aff ected by intracontinental rift ing, leading to the subsidence of the east–

west-trending East Srednegorie Basin Th is was

accompanied by widespread extrusion of volcanics

and a distinct uplift of its northern rift -shoulder

During the late Norian–Hettangian Early

Cimmerian Orogeny, this rift ed basin was

compressionally deformed and incorporated into

a foreland basin At the same time, the southern

parts of the Moesian Platform were deformed

into gentle north-verging anticlinal structures and

uplift ed, giving rise to the development of a regional

unconformity Th ese structures form the external

parts of the Early Cimmerian Strandzha Orogen that

fringed the Moesian Platform to the south (Tari et al 1997; Banks 1997; Georgiev et al 2001).

Pontides

In the western and central Pontides, evidence for Scythian to Carnian rift ing and associated alkaline magmatism comes from the İstanbul and Devrekani blocks, respectively Detachment of these blocks from the Scythian Platform resulted in the opening

of the presumably oceanic South Svanetia Basin, the northern parts of which probably correspond to the South Crimean Trough (Figure

intraplate volcanics

intraplate inversion

swells and orogens

continental slope subduction zone

Barents Sea Basin

P aspian Basin rec Dniepr Basin

Medveditsa Swell

Don-Donets Swell Karpinsky Swell

Stavropol Arch

Timan Swell

Pechora Swell

Pay-Khoy Orogen

URALIAN

MOUNT AIN BEL T

Moesian

main collision suture

Minsk

Warsaw

Oslo

St.-Petersburg Riga

İzmir-Ankara-Sevan ocean

5) (Ustaömer & Robertson 1994, 1997; Banks &

Robinson 1997; Stampfl i 2000; Stampfl i et al 2001a,

b; Stampfl i & Borel 2004) In both basins Upper

Triassic and Lower Jurassic fl ysch-type series were

deposited, partly on oceanic basement

According to Stampfl i (2000), Stampfl i et

al (2001a, b) and Stampfl i & Borel (2004) late

Permian–Early Triassic steepening and roll-back

of the Palaeotethys subduction zone, located along

the southern margin of the Pontides-Transcaucasus

terrane (Sakarya Zone), was accompanied by

back-arc rift ing controlling early to middle Triassic opening

of the oceanic South Crimean-Küre-Svanetia

back-arc basin Geochemical data on ophiolites, derived

from the Küre Basin, indicate that its oceanic crust

was generated under a supra-subduction setting and

thus, cannot be considered as part of Palaeotethys

s.str (Ustaömer & Robertson 1994, 1997; Banks &

Robinson 1997; Stampfl i 2000; Stampfl i et al 2001a,

b; Stampfl i & Borel 2004) During the late Permian–

early Triassic cycle of back-arc extension continental

fragments were also separated from the southern

margin of the Pontides Terrane (Şengör et al 1990;

Okay & Mostler 1994; Okay et al 1996; Yılmaz et

al 1997), possibly by arc-parallel shear movements

in response to oblique subduction of Palaeotethys

(Natal’in & Şengör 2005) Corresponding

Hercynian-deformed continental crustal slices occur in the

Permo–Triassic Karakaya accretionary wedge of

the Pontides-Sakarya Zone (Okay et al 2002)

Development of this accretionary wedge testifi es to

continued northward subduction of Palaeotethys

(Okay 2000; Okay et al 2002; Stephenson et al 2004).

Late Triassic (Carnian) collision and subduction

resistance of the Triassic Nilüfer oceanic plateau with

the Sakarya arc-trench system may underlay the onset

of the Early Cimmerian Orogeny and the associated

phase of back-arc compression (Ziegler et al 1998;

Okay 2000) In the course of the Early Cimmerian

orogenic cycle the remnant Palaeotethys was closed

and destroyed by the end of the Triassic (Yılmaz et

al 1997) in response to its northward subduction

beneath the Pontides-Sakarya terrane and partly by

subduction beneath the Cimmerian

Sanadaj-Sirjan-Elborz Terrane (Pickett & Robertson 1996; Okay

2000; Stampfl i et al 2001a, b) Th e end Triassic–

earliest Jurassic peak of the Early Cimmerian Orogeny

probably relates to docking of this Cimmerian terrane complex against the southern, active margin

of Eurasia (Pickett & Robertson 1996; Yılmaz et al 1997; Ziegler et al 1998; Okay 2000; Stampfl i et al

2001a, b)

Th e Late Triassic to Hettangian Erzincan suture, marking the boundary between the Sakarya and Cimmerian terranes to the south,

İzmir-Ankara-is characterized by the Permo–Triassic Karakaya, Orhanlar, Çal and Küre subduction-accretionary complexes, the middle to upper Norian syn-collisional arkosic Aodul unit and the Nilüfer ophiolites Signifi cantly, Hercynian basement slices occur both above and below Nilüfer ophiolites Eclogites and blueschists occurring along this suture yield ages in the range of 214–192 Ma and 205–215 Ma (Okay &

Monie 1997; Okay 2000; Okay et al 2002) Th e oldest post-orogenic deposits overstepping this suture are shallow-marine Sinemurian sandstones (Okay 2000)

Th e Early Cimmerian orogenic pulse aff ected apparently the entire Pontides and probably involved southward subduction of the South Crimean-Küre-Svanetia Basin, as a conjugate to the north-dipping Sakarya Palaeotethys subduction zone (Yılmaz

et al 1997; Banks & Robinson 1997; Ustaömer &

Robertson 1997; Stampfl i 2000; Stampfl i et al 2001a, b; Stampfl i & Borel 2004; Nikishin et al 2001).

East-European Platform

On the EEP, Triassic strata occur in the Mezen Basin, located to the north of Moscow (Figure

Moscow-5; Lozovsky 1992; Dercourt et al 2000), and in the

Polish part of the large Northwest European Basin (Ziegler 1990)

In the Moscow-Mezen Basin, lowest Permian–Lower Triassic strata are dominated by continental clastics (Milanovsky 1996; Lozovsky 1992; Lozovsky

& Esaulova 1998) Middle and Upper Triassic deposits are missing and Mid-Jurassic sediments rest

on truncated Lower Triassic clastics Whether Middle and Upper Triassic strata were deposited and eroded prior to the Mid-Jurassic transgression is uncertain.During Late Triassic and Early Jurassic times the EEP was apparently uplift ed, probably in response

to the build-up of compressional intraplate stresses originating in the Early Cimmerian Orogen along

its southern margin and in the Uralian Orogen

on its eastern margin Th is is compatible with the

development of minor inversion structures, such as

the Vyatka Swell that is superimposed on the Riphean

and Devonian Vyatka rift , the Oka-Tsna Swell along

Riphean Pachelma rift and the Don-Medveditsa Swell

along the Devonian Don-Medveditsa Rift (Figures 7

& 8; Nikishin et al 1996) However, as these inversion

structures were truncated and unconformably

covered by Mid-Jurassic series, the timing of their

development in not very closely constrained

On the other hand, the sedimentary record of the

Keuper series (Upper Ladinian to Lower Rhaetian)

in the eastern parts of the Northwest European Basin

clearly refl ects an episodic and progressive uplift of

the western parts of the EEP, possibly involving broad

lithospheric folding (Ziegler 1990)

Early Cimmerian Orogeny

During Late Triassic–Hettangian times, the southern

and northeastern margins of the EEP were sites of

essentially synchronous major orogenic activity

(Figures 7 & 8) Although the evolution of these two

orogenic systems was controlled by widely diff ering

plate kinematics, they testify to an important phase

of plate boundary reorganization

Th e Early Cimmerian Orogeny, which aff ected the

entire southern margin of the Scythian and Moesian

platforms, the Pontides and the Trans-Caucasus

domain, was associated with an important phase

of back-arc and intraplate compression In a N–S

direction, the area involved in the Early Cimmerian

Orogen extended from the Karpinsky Swell in the

north to the Pontides in the south over a distance of

some 700 km

In the course of the Early Cimmerian Orogeny,

the Palaeotethys was closed, the Sakarya subduction

system abandoned whilst a north-dipping Neotethys

subduction system developed along the southern

margin of the Cimmerian terranes (Figures 7 & 8;

Nikishin et al 1998b, 2001b; Stampfl i et al 2001a,

b; Ziegler & Stampfl i 2001; Stampfl i & Borel 2004;

Ustaömer & Robertson 2010) Th is was accompanied

by the build-up of major compressional stresses in

the back-arc domain of the South

Crimea-Küre-Svanetia Basin, causing its closure As in the domain

of the Great Caucasus the Early Cimmerian arc suture forms a linear zone, large-scale strike-slip movements may have occurred along it during Late Triassic-Hettangian times (cf model of Natal’in & Şengör 2005) Moreover, during the early phases of the Early Cimmerian Orogeny the north-dipping Sakarya subduction zone propagated apparently westwards, activating the southern margin of the Moesian Platform as evidenced by the development

back-of the Srednegorie Orogen (Pickett & Robertson

1996; Ustaömer & Robertson 1997; Stampfl i et al 2001a, b; Georgiev et al 2001).

Sinemurian to Mid-Callovian Mid-Cimmerian Tectonic Cycle

Following the Early Cimmerian orogenic pulse, the EEP was fl anked to the south by the north-dipping Neotethys subduction zone along the southern margin of the Pontides-Transcaucasus-Cimmerian terrane assembly (Figure 9) Sinemurian

to Aalenian development of a system of rift ed basins

on the Scythian Platform, rapid subsidence of the Great Caucasus-South Crimea Trough speak for a resumption of back-arc extension Th is cycle of back-arc extension came to an end at the transition from the Aalenian to the Bajocian with the onset of the Mid-Cimmerian Orogeny that terminated towards

the end Bathonian–early Callovian (Nikishin et al

2001, 2005; Ustaömer & Robertson 2010)

Great Caucasus – South Crimea

Th e large Great Caucasus deep-water basin came into evidence during the Early Jurassic To the west it probably linked up with the remnant South Cimea-Küre and North Dobrogea basins (Muratov 1969; Panov & Guschin 1987; Mazarovich & Mileev

1989a, b; Rostovtsev 1992; Panov et al 1994, 1996; Nikishin et al 1998a, b, 2001) Th e Early to Middle Jurassic chrono/lithostratigraphy for the eastern part

of this trough and the adjacent Scythian Platform is

given by Nikishin et al (2001) A tentative Toarcian

palaeogeographic reconstruction of the area is provided by the Figure 9

Th e Great Caucasus Trough began to subside during the Sinemurian, as indicated by the occurrence

of shallow-water clastics containing conglomerates

Upwards these grade into upper Pliensbachian to

lower Aalenian deeper-water shales (Figure 10a)

Rapid late Sinemurian and Pliensbachian subsidence

of this basin was accompanied by the extrusion

of basalts and rhyolites and the emplacement of numerous dyke swarms (Panov & Guschin 1987) Although Toarcian dykes consist of MORB-type basalts, there is no evidence for the occurrence of

I I I

I I I I I

I I II

II II I I

I I I

I

55

5normal faults

İzmir-Ankara-Sevan Ocean

Early Jurassic,

Early Toarcian

CARP A HIAN BASIN

CRIMEA - GREAT CAUCASUS BASIN

P aspian Basin

c Dniepr Basin

re-Polish Trough

deltaic, coastal and shallow

marine, mainly clastics

shallow marine, mainly clastics

shalow marine, mainly carbonates

deeper marine clastics and shales

oceanic floor

eroded land:

trough slopes arc-related

volcanism

MoscowMinsk

subduction zones spreading axes cratonic,

c

e

d b

Figure 10 Representative outcrops in the western Great Caucasus region (a) Aalenian deep-water shales to the north of Tuapse city

(Indyuk villiage region) (b) Upper Jurassic carbonate section Malaya Laba River near Psebay City Upper part– layered carbonate platform, middle and lower parts– sedimentary breccia, possible slope of carbonate build-up (c) Cenomanian pillow-basalts in Western Caucasus Trough, Agva River, north of Sochi City (d) Early Oligocene Maykopian sequence

on Agoy Beach near Tuapse City, showing alternation of shales and debris fl ows Debris fl ows contain fragments of

Cretaceous to Eocene Great Caucasus Trough sediments (e) Chevron folds close to Tuapse City involving Paleocene

pelagic cherts alternating with turbiditic siltstones.

Lower Jurassic ophiolites in the Great Caucasus

Th is questions whether in the Great Caucasus

Basin Early Jurassic crustal extension had proceed

to crustal separation and the opening of a small

back-arc oceanic basin Th e onset of compressional

deformation of the Great Caucasus-South Crimea

Trough was heralded by the upper Aalenian and

Bajocian infl ux of breccias and coarser clastics along

its southern margin (Nikishin et al 2001) However,

in its central parts marine sedimentation persisted

until late Bathonian times

In the Trans-Caucasus area, the occurrence of

very thick island-arc volcanics, dated as Sinemurian

to Hauterivian (Nikishin et al 2001, 2005; Zakariadze

et al 2007) with a Bajocian maximum, refl ects

increased activity along the Neotethys subduction

zone during the Mid-Cimmerian Orogeny (Figures

11 & 12)

Scythian Platform

Th e Scythian Platform, forming the northern

shoulder of the Great Caucasus-South Crimea rift ed

basin, remained an area of non-deposition during

Sinemurian times However, during the Pliensbachian

and Toarcian, it was transected by a system of narrow,

probably extensional, shallow-water basins (Panov et

al 1996) Pliensbachian subsidence of these basins

was accompanied by the extrusion of rhyolites,

dacites, andesites and basalts (Panov & Guschin

1987; Hess et al 1993) Th e Scythian Platform was

broadly overstepped during the late Aalenian and

Bajocian by shallow marine sediments, which were

deposited in a foreland-type basin

Th e bimodal volcanism occurring in the Great

Caucasus-South Crimea Trough and on the Scythian

Platform was initially interpreted as

subduction-related (Hess et al 1993), but is now considered as

rift -related (Koronovsky et al 1997) Nevertheless,

there is some evidence for a possible Early Jurassic

andesitic, probably subduction-related volcanism

in the Transcaucasus region (Lordkipanidze

1980; Knipper et al 1997; Ustaömer & Robertson

2010) According to our interpretation, the upper

Sinemurian to lower Pliensbachian rhyolitic volcanics

of the Great Caucasus area refl ect a combination of

subduction- and rift -related magmatism, implying

that the Great Caucasus Trough developed by arc extension involving the disruption of a magmatic arc

back-South Crimea Trough

Aft er its partial inversion at the Triassic–Jurassic transition, subsidence of the South Crimea Trough resumed and persisted until the end of the Early

Jurassic–beginning of Aalenian (Nikishin et al 2001)

Its earliest Middle Jurassic pre-Aalenian (or Aalenian) inversion resulted in intense folding of the Triassic to Lower Jurassic Tavric fl ysch, which is unconformably overlain by Aalenian–Early Bajocian paralic and molasse series and Upper Bajocian arc-related volcanics (Figure 13a–c) In turn, these are unconformably covered by upper Callovian red-beds, giving upwards way to Oxfordian and younger carbonates Inversion of the South Crimea Trough was accompanied (?) and followed by subduction-related calc-alkaline, mainly Bajocian magmatic activity, including the intrusion of gabbros, diorites and plagiogranites (Muratov 1969) Th e Middle Jurassic age of this magmatism is supported by

intra-new Ar/Ar datings (~169; 172–160 Ma) (Meijers et

South Crimea extended westwards into the area of the North Dobrogea where Middle Jurassic fl ysch-type clastics testify to continued inversion movements

(Nikishin et al 2000; Seghedi 2001, 2009).

Central Pontides

Th e Küre fl ysch of the Central Pontides is considered

to be equivalent to the Tavric fl ysch of Crimea (Robinson & Kerusov 1997; Ustaömer & Robertson 1997) In the Pontides domain, the Küre Basin was closed during the Mid-Cimmerian Orogeny Th is was accompanied by the obduction of oceanic crust, and a Middle Jurassic intrusive, subduction-related

magmatism (Ustaömer & Robertson 1997; Yılmaz et

al 1997).

Eastern Pontides

In the external domain of the Eastern Pontides, which

at this time was located adjacent to the Caucasus area, an E–W-trending East Pontides Basin began

I I I

I I I I I normal faults

palaeoenvironments

and sediments

shallow marine, sands and shales

continental, sands and shales

oceanic floor

arc-related volcanism rift-related volcanism

eroded land:

trough slopes subsidence axes

subduction zones spreading axes low relief

Pechora Basin

c

e e

I I I

I I I I I normal faults

palaeoenvironments

and sediments

shallow marine, sands and shales

shallow marine, shales and carbonates

shallow marine, mainly carbonates

I I I

I I I I I I

I

I

I CARP

AT HIAN BASIN

C A U C A S U S

P O N T I D E S S.CRIMEA

DOBROGEA

Polish Trough

Moesian Platform

Moc

w- M e e

Ba

i n

Pechora Basin

~12 metres

Synrift 2, carbonates, olistoliths

Synrift 2, carbonates, olistoliths

Synrift 1, conglomerates

Synrift 1, conglomerates

Shallow-marine carbonates

Shallow-marine carbonates

a

c

d b

Figure 13 Representative outcrops in the Southern Crimea (a) Lower Jurassic part of the Tavric Flysch, Bodrak River,

Bakhchisaray region, showing alternation of turbiditic sandstones, siltstones and shales and pelagic shales (b)

Aalenian to Early Bajocian Bitak Molasse near Simpheropol City, Strogonovka Village, consisting of conglomerates

and sandstones (c) Coastal cliff exposing Bajocan pillow-basalts at Cape Fiolent close to Sevastopol and Balaklava

(d) Callovian to Oxfordian(?) synrift conglomerates, debris fl ows and carbonates of Pakhkal-Kaya section close to

Alushta City and Demerdzhi Mountain (e) Late Jurassic deep-water turbiditic conglomerates, Ordzhonikidze City, East Crimea, Feodosia region (f) Callovian–Late Jurassic(?) Koba-Kaya carbonate build-up with marginal slope,

close to Nonvyi Svet City, Sudak region.

to subside during the Sinemurian–Pliensbachian

and persisted until at least the end of the Bathonian

(Okay & Şahintürk 1997) Its sedimentary fi ll consists

of up to 2000-m-thick paralic and later turbiditic

conglomeratic and sandy series, referred to as the

Kelkit Formation It contains abundant volcaniclastic

material and intercalations of carbonates in Rosso

Ammonitico facies, and rests unconformably on

Palaeozoic high-grade metamorphic rocks and

locally on Carboniferous conglomerates Further to

the south, Kelkit equivalent sediments are developed

in fi ner-grained pelagic facies (Okay & Şahintürk

1997) Th e East Pontides Basin may have formed

a branch of the Great Caucasus-South Crimea rift

system However, biostratigraphic control on the

Lower Jurassic sediments of the Eastern Pontides

leaves to be desired (Robinson et al 1995), and

additional data are required to support these tectonic

concepts Th e occurrence of signifi cant amounts

of basalts, andesites and tuff s are compatible with

the postulate that the Eastern Pontides and the

Transcaucasus were associated with an Early–Middle

Jurassic subduction-related volcanic arc (Robinson

et al 1995; Banks & Robinson 1997; Nikishin et al

1998a, b, 2001; Yılmaz et al 2000) Th is concept is

compatible with the results of new investigations

on the Jurassic magmatism of the Eastern Pontides

(Moix et al 2008; Genç & Tüysüz 2009; Ustaömer &

Robertson 2010)

Moesian Platform

On the Moesian Platform, sedimentation was

interrupted during the Early Jurassic and only

resumed during the Bathonian–Callovian with the

deposition of thin continental and marginal marine

clastics (Harbury & Cohen 1997) However, along its

southern margin, the East Srednegorie-Balkan rift

was reactivated during the Early Jurassic In this basin

an over 1500-m-thick Lower and Middle Jurassic

deeper-water sequence accumulated, consisting of

Pliensbachian–Toarcian sandy and conglomeratic

turbiditic series, containing olistoliths which consist

of Palaeozoic, Triassic and Lower Jurassic rocks Th e

evolving rift included also the Strandzha zone, which

had formed the southern fl ank of this rift during the

Triassic During the Aalenian and Bajocian, rift ing

activity terminated and the basin subsided probably

in response to the build-up of compressional stresses, receiving an over 1500-m-thick shale dominated sequence During the end Bathonian culmination

of the Mid-Cimmerian Orogeny, the Balkan Basin was partly inverted Along its northern margin deformed Lower and Middle Jurassic series are unconformably overlain by Callovian–Oxfordian carbonates which broadly overstepped the Moesian

Srednegorie-Platform (Banks 1997; Georgiev et al 2001).

Th e Srednegorie-Balkan Basin probably extended eastwards between the İstanbul and the Sakarya blocks where Early Jurassic rift ing progressed

to crustal separation and the opening of a small oceanic basin; this basin was closed again during the Neocomian (or before Late Eocene?) (Intra-Pontides suture; Okay & Tüysüz 1999; Okay 2000)

Great Caucasus-South Crimea Trough

In view of the above, it is compelling to interpret the Early Jurassic Great Caucasus-South Crimea and Srednegorie-Balkan troughs as a system of back-arc

extensional basins (Figure 9; Nikishin et al 1998a, b,

2001, 2005) Main points supporting a rift ed origin of this, now totally inverted basin complex are its rapid subsidence, the uplift of its northern shoulder at the beginning of basin subsidence, and the presence of a bimodal volcanism, which spread onto the Scythian Platform as the main basins subsided rapidly Th e Early Jurassic Great Caucasus-South Crimea back-arc basin, that was probably characterized by a drastically thinned continental crust, can be readily compared to recent back-arc basins, such as the East Black Sea Basin, the width of which is close

to 200 km In our reconstruction of the area under consideration we assumed similar dimensions for the Early Jurassic Great Caucasus-South Crimean deep-water trough

Th e Middle Jurassic Mid-Cimmerian phase of back-arc compression, which aff ected the Great Caucasus-South Crimea Trough and the Eastern and Central Pontides (Figure 11), as well as the Western Pontides and the Rhodope-Strandzha domain, can be related to changes in the geometry

of the Neotethys subduction zone and the activation

of subduction processes along the southern margin

of the Pontides Th is coincided with a major plate

boundary reorganization involving amongst others,

opening of the Central Atlantic and Alpine Tethys

(Georgiev et al 2001; Stampfl i et al 2001a; Ziegler

et al 2001).

Th e Great Caucasus Trough was partially

inverted, mainly along its northern margin, during

late Aalenian to Bathonian times, with most intense

deformation at the Aalenian/Bajocian boundary

and during the Bathonian (Panov & Guschin 1987;

Belov et al 1990; Koronovsky et al 1997; Nikishin

South Crimea Trough underwent a fi rst phase

of compressional deformation during the late

Aalenian–early Bajocian and a second one during the

Bathonian–earliest Callovian (Nikishin et al 1998a,

b, 2001) Th is coincided with the deformation of the

Central Pontides Küre Basin (Ustaömer & Robertson

1997), whilst in the Eastern Pontides and the

Transcaucasus region the main deformation phase is

Aalenian (Robinson et al 1995) and pre-Bajocian in

age, respectively

In the North Dobrogea Basin, there is little

evidence for an Early Jurassic extensional phase;

accumulation of fl ysch-type clastics, derived from

southwestern sources, that had commenced during

the late Carnian, persisted during Early and Middle

Jurassic times, and was accompanied by the

Mid-Jurassic propagation of north-verging thrusts into

its sedimentary fi ll (Nikishin et al 2000; Seghedi

2001) To the north of the evolving North Dobrogea

orogen, a molasse basin, containing 1600 m of clastic

sediment, developed during the Middle Jurassic

(Kruglov & Tsypko 1988) Also in the Strandzha

Zone of the Balkanides and in the

Srednegorie-Balkan Basin, a Bathonian compressional event has

been recorded (Banks 1997; Georgiev et al 2001).

East European Platform

During the Hettangian to Aalenian, nearly all of

the EEP was located above sea level and, thus, was

subjected to erosion (Milanovsky 1996; Dercourt et

al 2000) Only from mid-Bajocian to Callovian time

onwards did some basins begin to subside again, as

evidenced by the accumulation of shallow-water to

continental sediments in the Dniepr, Precaspian and

Moscow-Mezen-Pechora basins (Figures 8, 9, 11 &

12) Correspondingly, we are unable to assess whether intraplate deformations occurred on the EEP during the Mid-Cimmerian tectonic cycle

Neo tethys Subduction System

Th ere is considerably controversy about the Early and Middle Jurassic evolution of active southern margin

of the EEP (Ziegler et al 2001; Stampfl i & Borel 2004; Nikishin et al 2001, 2005; Okay et al 2006; Moix et

al 2008) One interpretation suggests that during

Early Jurassic times northward subduction of the Neotethys Ocean beneath the southern margin of the Cimmerian Menderes, Taurus and Sanandaj-Sirjan blocks continued whilst the oceanic İzmir-Ankara-Erzincan-Sevan back-arc basin opened During Middle Jurassic accelerated subduction of the Neotethys underlying the Mid-Cimmerian Orogeny,

an arc-trench system may have been activated along the southern margin of the Sakarya-Pontides-Transcaucasus terrane in response to back-arc compression, controlling northward subduction and partial closure of the İzmir-Ankara-Erzincan-Sevan back-arc basin (Robertson & Dixon 1984; Yılmaz

et al 1997; Dercourt et al 2000; Floyd et al 2000;

Stampfl i 2000; Stampfl i et al 2001a, b; Ziegler et al

2001; Stampfl i & Borel 2004)

On the other hand, Okay (2000), Nikishin et

al (2001, 2005), Okay et al (2006) and Ustaömer

& Robertson (2010) contend that Cimmerian continental terranes were docked during the Early Cimmerian orogeny against the southern margin

of the Sakarya-Pontides-Transcaucasus terrane, and therefore postulate that along their southern margin subduction processes were continuously active during Early and Middle Jurassic times

Ophiolites and their cover contained in the

Sevan suture consist, according to Zakariadze et al

(2000), of (a) a complete sequence of island arc type tholeitic ophiolites (225±10 Ma, Sm-Nd, Rb-Sr), (b) a complete boninitic ophiolite sequence (160±4

Ma, U-Pb; 162±8 Ma, K-Ar) and (c) a sedimentary sequence consisting of an alternation

volcano-of MORB- and OIB-type volcanics and pelagic and shallow-water sediments ranging in age from Late Triassic to Coniacian Moreover, Sm-Nd mineral

isochrones obtained on garnet-amphibolites from a

serpentinitic mélange and olistostromes show ages

in the range of 224±6 Ma, 155±11 Ma, and 86±10

Ma Th ese data show that along the Sevan suture

subduction processes were intermittently active

from Triassic to Late Cretaceous times Furthermore,

Zakariadze et al (2000) show that in the Trans-Great

Caucasus region, located northward adjacent to the

Sevan suture, subduction-related magmatic activity

occurred around 230 Ma (tholeiitic basalts), 200 Ma

(calc-alkaline rhyolites, diorites and quartz-diorites),

180–160 Ma (island-arc volcanics) and 150–140 Ma

(island-arc volcanics) Th is refl ects intermittent, yet

persistent subduction activity in the Sevan sector

of the İzmir-Ankara-Erzincan-Sevan suture Th is

is compatible with the concepts of Okay (2000),

Nikishin et al (2001, 2005), Okay et al (2006) and

Galoyan et al (2009).

Nevertheless, and in view of unequivocal

evidence for Late Triassic accretion of the Cimmerian

Sanandaj-Sirjan terrane to the southern margin of

Laurasia in Iran, the Mid-Cimmerian tectonic cycle

of the Black Sea domain can be interpreted as having

been controlled by activity along the Neotethyan

subduction system (Stampfl i 2000; Sampfl i et al

2001a, b) Following its development during the

Early Cimmerian Orogeny, involving subduction

progradation from the Sakarya arc-trench system

to the southern margin of the East-Cimmerian

terranes, subduction rates apparently decreased

during Sinemurian to Aalenian times, giving rise

to a phase of back-arc extension, including opening

of the oceanic İzmir-Ankara Basin (Stampfl i &

Borel 2004) However, during Late Aalenian times

subduction rates increased again, controlling the

onset of back-arc compression, culminating during

the Bajocian, causing partial closure of the

İzmir-Ankara Basin, closure of the Srednegorie-Balkan

Basin and inversion of the Crimea-Great Caucasus

Trough Th e Mid-Cimmerian Orogeny coincides

with an important plate boundary reorganization in

the Tethyan and Atlantic domains, involving Early

Jurassic termination of sea-fl oor spreading in the

Neotethys and the onset of sea-fl oor spreading in the

Vardar Ocean during the Sinemurian–Toarcian, in

the Central Atlantic during the Toarcian and in the

Alpine Tethys during the Bajocian (Stampfl i et al

2001a, b; Ziegler et al 2001; Stampfl i & Borel 2004).

Callovian to Berriasian Late Cimmerian Tectonic Cycle

Aft er the Mid-Cimmerian orogenic phase, the Black Sea domain was aff ected by a new rift ing cycle that commenced during the Callovian and terminated with the Berriasian Late Cimmerian compressional

event (Nikishin et al 1998a, b, 2001, 2005).

During the Late Jurassic and Early Cretaceous,

a carbonate-shale-evaporite shelf occupied much of the Scythian Platform Th is shelf was disrupted by Callovian to Late Jurassic rift ing, giving rise to the subsidence of the South Caspian-Great Caucasus Trough (located mainly in the southern parts of the present Great Caucasus), the Terek, West Kuban and East Kuban basins located on the northern shoulder

of the Great Caucasus Trough, as well as the Dobrogea and the South Crimea basins (Figures 14–16)

Similarly, the Pontides and Strandzha-Balkanides Zone were aff ected by Late Jurassic crustal extension that variably terminated during the Kimmeridgian

and Early Cretaceous (Yılmaz et al 1997; Bank & Robinson 1997; Georgiev et al 2001; Uastaömer

& Robertson 2010) In the Western, Central and Eastern Pontides, Upper Jurassic basal clastics, unconformably overlaying a mosaic of metamorphic and sedimentary rocks, display rapid lateral thickness changes related to extensional faulting Upward these basal clastics grade into Upper Jurassic and Lower Cretaceous carbonates, which form a southward expanding ramp refl ecting the development of a

‘continental margin prism’ facing the İzmir-Ankara

(Neotethys for this times) oceanic basin (Yılmaz et al 1997; Okay & Şahintürk 1997; Nikishin et al 2001, 2005; Stampfl i et al 2001a, b; Ustaömer & Robertson

2010)

Great Caucasus Trough

In the domain of the Great Caucasus Trough, a regional angular base Callovian unconformity testifi es to the Mid-Cimmerian inversion of this basin prior to its renewed Callovian–Late Jurassic subsidence (Panov

& Guschin 1987; Milanovsky 1996; Koronovsky et al

1997) Th e Callovian to Berriasian series is developed

in relatively deep-water, turbiditic facies and attains thicknesses of a few kilometres (Milanovsky 1996;

Nikishin et al 2005) During Callovian to Eocene

shallow marine, mainly shales

shalow marine, mainly carbonates

shallow marine, carbonates and clastics

oceanic floor arc-related volcanism; volcanic arcs

subsidence axes

subduction zones

spreading axes cratonic and inactive foldbelt, low relief

tectonic symbols:

Abbreviations: EK

WK SB SC

- East-Kuban Basin,

- Kuban Basin,

West SrednegorieWest Balkan Basin,

Srednegorie South Crimea Basin

Pechora Basin

Moc

w- Me e

Moesian Platform

EK WK SC

KarkinitBas

in

Tra ns ca ucasus arc

Sana

ndaj-S irjan arc

Vorkuta

Oslo

İzmir-A nkara-Sevan

Ocean

Figure 14 Kimmeridgean–Tithonian palaeogeograpnic/palaeotectonicpaleotectonic map of the East-European Platform (modifi ed

aft er Nikishin et al 2005).

times the Great Caucasus Trough probably consisted

of two sub-basins with the Central Caucasus High

(corresponding to the present day metamorphic core

of the Great Caucasus) partly separating the Western

Caucasus Basin from the Eastern Caucasus Basin

(Figure 16) Upper Callovian–Oxfordian alkaline

basalts occur in Georgia to the south of the Great

Caucasus Trough in the Rioni Basin (Topchishvili

ophiolites in the Great Caucasus suggests that rift ing

may not have progressed to crustal separation and the

opening of an oceanic basin in the Black Sea-Great

Caucasus area However, further to the east, in the

ultra-deep South Caspian Basin, now containing up

to 25-km-thick sediments, Callovian rift ing probably

culminated in crustal separation and sea-fl oor spreading during the Late Jurassic phase of back-arc extension (Zonenshain & Le Pichon 1986; Dercourt

et al 1993; Abrams & Narimanov 1997; Nadirov et al

1997; Nikishin et al 2001, 2005; Stampfl i et al 2001a, b; Brunet et al 2003) At the Jurassic/Cretaceous

transition the Great Caucasus Trough was aff ected by minor compressional deformation, which is not yet suffi ciently constrained

West and East Kuban and Terek Basins

Th e West and East Kuban and Terek basins contain 2–3-km-thick Callovian–Upper Jurassic sediments

(Figure 14; Koronovsky et al 1997; Milanovsky

Dobrogea

Black Sea region: main terranes

have been moved terranes, outlines of seas was not changed

Dzirula

Stable Eastern European ontinentCStable Eastern European ontinentC

WBSS

WBSS– West Black Sea-Saros Fault

Figure 15 Main continental terranes of the Black Sea domain as used in our palaeotectonic restoration maps given in Figures

16–18, 21–23, 26 & 27 (modifi ed aft er Nikishin by Afanasenkov et al 2007).

1996; Nikishin et al 1998a, b, 2001; Dercourt et al

2000) Callovian–lower Oxfordian sediments consist

of conglomerates, silts, clays and shallow marine

carbonates During the middle and late Oxfordian,

reef belts fringed the more rapidly subsiding central

parts of these basins (see Figure 10b) During the

Kimmeridgian and Tithonian, the northern fl ank

of the Great Caucasus Trough was uplift ed, forming

a low relief high (Milanovsky 1996) Th is caused

restriction of the basins located on the Scythian

Platform in which an evaporite-dominated series

accumulated Rapid subsidence of these North

Caucasus basins was probably controlled by crustal

extension, related to the re-opening of the Great

Caucasus back-arc trough (Bolotov 1996; Nikishin et

al 1994, 1998a, b, 2001) At the end of the Tithonian

and during the Berriasian, the North Caucasus basins were gently deformed and the entire area was uplift ed in conjunction with the Late Cimmerian compressional event, as evidenced by an angular unconformity recognized on refl ection-seismic lines that corresponds either to the Jurassic/Cretaceous

boundary or to an intra-Berriasian level (Nikishin et

Western Caucasus Trough

Eastern Caucasus Trough

Rioni Basin

Shatsky

Andrusov

Kura Moesia

İstanbul

E.Pontides

E.E.Pont CCH

CCH - Central Caucasus High

Sakar a y

continental

& shallow-marine deposits

reef belt

reef belt

Volcanic arc slope

eroded land

turbidites carbonate platform

carbonate platform pelagic carbonates, shales

isolated carbonate or reef build-up

However, crustal extension led to the subsidence of

the South Crimea Basin in which Callovian to lower

Berriasian sediments consist of shallow- to relatively

deep-water conglomerates, carbonates, and turbidite

deposits which attain thicknesses of several 100

metres (Figures 13e–f & 14) (Muratov 1969) During

the Berriasian, the South Crimea Basin region was

uplift ed and subjected to erosion (Figure 17) possibly

in response to compressional event (Nikishin et al

2005)

Moesian Platform and North Dobrogea Basin

During the Late Jurassic and Early Cretaceous, the

Moesian Platform was covered by an extensive

carbonate shelf that was fringed to the south in the

Srednegorie-Balkan area by a narrow east–west-

trending, probably rift -induced deeper-water trough

in which thick, coarse turbiditic clastics derived

from a southern source accumulated Following

a late Kimmeridgian–early Tithonian extensional

event, this basin was converted during the Late

Cimmerian Orogeny into a fl exural foreland basin

that was fl anked to the south by the rising

Strandzha-Srednegorie zone From the latter up to 3 km of

clastics were shed into this basin, the axis of which

migrated northward until it was completely fi lled in

late Berriasian times During the Mid-Cretaceous,

this basin was compressionally deformed, resulting

in the development of the Balkan fold-and-thrust

belt and of a regional unconformity on the Moesian

Platform (Harbury & Cohen 1997; Sinclair et al

1997; Georgiev et al 2001).

In the area of the North Dobrogea Basin,

inversion movements had ceased at the end of the

Middle Jurassic, as evidenced by the resumption

of carbonate sedimentation during Oxfordian–

Kimmeridgian times Kimmeridgian basalts,

occurring along its southwestern margin, are

indicative of its transtensional reactivation prior to

the end Jurassic–earliest Cretaceous resumption

of inversion movements (Sandulescu et al 1995;

Seghedi 2001, 2009)

During the Late Jurassic, also the eastern margin

of the Moesian Platform was apparently aff ected

by crustal extension (Beloussov & Volvovsky 1989;

Nikishin et al 1998a, b, 2001) Th is is indicated by the

transition from a shallow-water carbonate platform

on the Bulgarian Varna Block to a zone of

deeper-water sediment starvation to the east (Dachev et al

Dynamics of the Late Cimmerian Cycle

Following the Mid-Cimmerian Orogeny, back-arc extension, probably controlled by rollback of the Neotethys subduction zone, governed the Callovian

to Late Jurassic evolution of a system of rift ed basins

on the southern parts of the Scythian Platform and in the Black Sea domain, as well as opening of the Great Caucasus-South Caspian basin At the same time the Alpine Tethys seafl oor spreading axis propagated

into the Alpine-Carpathian domain (Nikishin et al 1998a, b, 2001; Golonka 2000; Stampfl i et al 2001a, b; Stampfl i & Borel 2004; Schmid et al 2008).

Th e Late Cimmerian compressional pulse refl ects a renewed, short-lived phase of back-arc compression, which induced on the Scythian Platform mild inversion of Late Jurassic tensional basins, development of a regional unconformity

in the South Crimea Basin region and minor deformation of the Great Caucasus Trough Whereas the Late Cimmerian orogenic pulse was apparently

of relatively minor importance in the Pontides, it is clearly expressed in the Rhodope-Strandzha zone

(Banks & Robinson 1997; Banks 1997; Georgiev et

al 2001) During the Late Cimmerian Orogeny,

northward subduction of Neotethys continued, and the Vardar arc collided with the Rhodope and the

adjacent Carpathian/Dinarides domains (Stampfl i et

al 2001a, b; Schmid et al 2008).

Valanginian to Palaeogene Early Alpine Tectonic Cycle

During the Early Cretaceous progressive opening of the Central Atlantic Ocean and rift ing in the Arctic-