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S. ADAMIA ET AL.
489
Geology of the Caucasus: A Review
SHOTA ADAMIA
1
, GURAM ZAKARIADZE
2
, TAMAR CHKHOTUA
3
,
NINO SADRADZE
1,3
, NINO TSERETELI
1
, ALEKSANDRE CHABUKIANI
1
&
ALEKSANDRE GVENTSADZE
1
1
M. Nodia Institute of Geophysics, 1/1 M. Alexidze str., 0171, Tbilisi, Georgia
(E-mail: sh_adamia@hotmail.com)
2
Vernadsky Institute of Geochemistry and Analytical Chemistry, RAS, 119991, Moscow, Russia
3
Al. Janelidze Institute of Geology, 1/9 M. Alexidze str., 0193, Tbilisi, Georgia
Received 15 May 2010; revised typescripts receipt 30 January 2011 & 14 January 2011; accepted 11 April 2011
Abstract: e structure and geological history of the Caucasus are largely determined by its position between the still-
converging Eurasian and Africa-Arabian lithospheric plates, within a wide zone of continental collision. During the
Late Proterozoic–Early Cenozoic, the region belonged to the Tethys Ocean and its Eurasian and Africa-Arabian margins
where there existed a system of island arcs, intra-arc ri s, back-arc basins characteristic of the pre-collisional stage of
its evolution of the region. e region, along with other fragments that are now exposed in the Upper Precambrian–
Cambrian crystalline basement of the Alpine orogenic belt, was separated from western Gondwana during the Early
Palaeozoic as a result of back-arc ri ing above a south-dipping subduction zone. Continued ri ing and sea oor
spreading produced the Palaeotethys Ocean in the wake of northward migrating peri-Gondwanan terranes. e
displacement of the Caucasian and other peri-Gondwanan terranes to the southern margin of Eurasia was completed
by ~350 Ma. Widespread emplacement of microcline granite plutons along the active continental margin of southern
Eurasia during 330–280 Ma occurred above a north-dipping Palaeotethyan subduction zone. However, Variscan and
Eo-Cimmerian–Early Alpine events did not lead to the complete closing of the Palaeozoic Ocean. e Mesozoic Tethys
in the Caucasus was inherited from the Palaeotethys. In the Mesozoic and Early Cenozoic, the Great Caucasus and
Transcaucasus represented the Northtethyan realm – the southern active margin of the Eurasiatic lithospheric plate.
e Oligocene–Neogene and Quaternary basins situated within the Transcaucasian intermontane depression mark
the syn- and post-collisional evolution of the region; these basins represented a part of Paratethys and accumulated
sediments of closed and semiclosed type. e nal collision of the Africa-Arabian and Eurasian plates and formation
of the present-day intracontinental mountainous edi ce of the Caucasus occurred in the Neogene–Quaternary period.
From the Late Miocene (c. 9–7 Ma) to the end of the Pleistocene, in the central part of the region, volcanic eruptions in
subaerial conditions occurred simultaneously with the formation of molasse troughs.
e geometry of tectonic deformations in the Transcaucasus is largely determined by the wedge-shaped rigid
Arabian block intensively indenting into the Asia Minor-Caucasian region. All structural-morphological lines have
a clearly-expressed arcuate northward-convex con guration re ecting the contours of the Arabian block. However,
farther north, the geometry of the fold-thrust belts is somewhat di erent – the Achara-Trialeti fold-thrust belt is, on the
whole, W–E-trending; the Greater Caucasian fold-thrust belt extends in a WNW–ESE direction.
Key Words: Caucasus, convergence, collision, Eurasia, Gondwana, volcanism
Ka asların Jeolojisi
Özet: Ka asların yapısını ve jeolojik tarihini denetleyen ana unsur birbirine yaklaşan Avrasya ve Afrika-Arabistan
levhaları arasındaki konumudur. Geç Proterozoyik ile Tersiyer arasında Ka aslar, Tetis okyanusu ve bu okyanusun
Avrasya ve Afrika-Arabistan kıta kenarları içermekteydi; bu sistem içerisinde yer alan ada yayları, yay-içi ri ler, yay-ardı
havzalar Ka asların çarpışma öncesi jeoloji tarihinin bir parçasını teşkil eder. Erken Paleozoyik’te batı Gondwana’nın
altına güneye doğru dalan bir dalma-batma zonu üzerinde gelişen yay-ardı ri leşme ile Ka aslar, ve Alpin orojenik
kuşak içinde yer alan diğer üst Prekambriyen–Kambriyen kristalen temel parçaları, Gondwana’dan ayrılmıştır. Kuzeye
hareket eden bu Gondwana-çevresi (peri-Gondwana) mıntıkalarının güneyinde Paleotetis okyanusu açılmıştır. Ka asya
ve diğer Gondwana-çevresi mıntıkalarının Avrasya güney kenarını eklenmesi ~350 Ma’de tamamlanmıştır. Avrasya
kıta kenarının altına kuzeye doğru dalan bir dalma batma zonu üzerinde yaygın mikroklinli granitoid plutonlarının
yerleşimi 320–280 Ma aralığında gerçekleşmiştir. Tüm bu Variskan, Eo-Kimmeriyen ve erken Alpin olaylara rağmen
Ka asların güneyindeki Paleozoyik okyanusunun tamamen kapanmamış, ve Mesozoyik Tetis Paleotetis’ten miras
Turkish Journal of Earth Sciences (Turkish J. Earth Sci.), Vol. 20, 2011, pp. 489–544. Copyright ©TÜBİTAK
doi:10.3906/yer-1005-11 First published online 11 April 2011
THE GEOLOGY OF THE CAUCASUS
490
Introduction
e structure and geological evolution of the
Caucasian segment of the Black Sea-Caspian Sea
region (Figure 1) are largely determined by its
position between the still converging Eurasian and
Africa-Arabian lithosphere plates, within a wide
zone of continent-continent collision. Problems of
Late Proterozoic–Phanerozoic development of this
area have been considered and discussed during
the past decades in a great number of publications.
According to some authors (Khain 1975; Adamia
1975; Adamia et al. 1977, 1981, 2008; Giorgobiani
& Zakaraia 1989; Zakariadze et al. 2007), the region
in the Late Proterozoic, Palaeozoic, Mesozoic, and
Early Cenozoic belonged to the now-vanished Tethys
Ocean (Prototethys, Palaeotethys, Tethys) and its
Eurasian and Gondwanan/Africa-Arabian margins.
Within this ocean-continent convergence zone,
there existed a system of island arcs, intra-arc ri s,
and back-arc basins etc. characteristic of the Late
Proterozoic–Early Cenozoic pre-collisional stage
of evolution of the region. During syn-collisional
(Oligocene–Middle Miocene) and post-collisional
(Late Miocene–Quaternary) stages of the Late Alpine
tectonic cycle, as a result of Africa-Arabia and Eurasia
collision back-arc basins were inverted to form
fold-thrust belts in the Great and Lesser Caucasus
and, in between, the Transcaucasian intermontane
depression. Normal marine basins were replaced by
semi-closed basins of euxinic type (Paratethys) and
later on (Late Miocene) by continental basins with
subaerial conditions of sedimentation (Milanovsky
& Khain 1963; Gamkrelidze 1964; Andruschuk 1968;
Azizbekov 1972; Geology of the USSR 1977; Jones &
Simons 1977; Eastern Paratethys 1985; Vincent et al.
2007; Adamia et al. 2008; Okay et al. 2010).
Main Tectonic Units
e Caucasus is divided into several main tectonic
units or terrains (Figure 2). ere are platform
(sub-platform, quasi-platform) and fold-thrust
units, which from north to south are: the Scythian
(pre-Caucasus) young platform, the fold-thrust
mountain belt of the Great Caucasus including
zones of the Fore Range, Main Range, and Southern
Slope, the Transcaucasian intermontane depression
superimposed mainly on the rigid platform zone
(Georgian massif), the Achara-Trialeti and the
Talysh fold-thrust mountain belts, the Artvin-Bolnisi
rigid massif, the Loki (Bayburt)-Karabagh-Kaphan
fold-thrust mountain belt, the Lesser Caucasus
ophiolitic suture, the Lesser Caucasian part of the
Taurus-Anatolia-Central Iranian platform, and
the Aras intermontane depression at the extreme
south of the Caucasus. e youngest structural unit
is composed of Neogene–Quaternary continental
volcanic formations of the Armenian and Javakheti
plateaus (highlands) and extinct volcanoes of the
Great Caucasus – Elbrus, Chegem, Keli, and Kazbegi.
Within the region, Upper Proterozoic–
Phanerozoic sedimentary, magmatic, and
metamorphic complexes are developed. eir
formation occurred under various palaeogeographic
and geodynamic environments: oceanic and small
oceanic basins, intercontinental areas, active and
kalmıştır. Mesozoyik ve erken Tersiyer’de, Büyük Ka aslar ve Transka asya, Avrasya’nın levhasının güney aktif kıta
kenarını, bir diğer ifade ile kuzey Tetis bölgesini temsil ediyordu.
Transka aya’nın dağ arası çöküntü bölgelerinde gelişen Oligosen–Neojen ve Kuvaterner havzalar bölgenin çarpışma
ve çarpışma sonrası evrimini temsil eder. Bu havzalar Paratetisin bir kesimini temsil eder ve sedimanları kapalı veya
yarı-kapalı havzalarda çökelmiştir. Afrika-Arabistan ve Avrasya levhalarının nihai çarpışması ve bugünkü kıtalararası
Ka aya dağ kuşağının oluşumu Neojen–Kuvaterner’de meydana gelmiştir. Geç Miyosen’den (9–7 Ma) Pleistosen’in
sonuna kadar geçen zamanda Ka a arın merkezi kesimlerinde volkanik faaliyetler meydana gelmiş ve molas havzaları
oluşmuştur.
Transka asya’daki tektonik deformasyonun geometrisini kontrol eden ana etken kama şeklinde sert Arabistan
blokunun Anadolu-Ka asya bölgesine saplanmasıdır. Buna bağlı olarak tüm yapısal-morfolojik çizgilerin, Arabistan
levhasının kuzey sınırını yansıtan bir şekilde, kuzeye doğru içbükey bir geometri gösterir. Buna karşın daha kuzeyde
kıvrım-bindirme kuşaklarının geometrisi farklıdır – Acara-Trialeti kuşağının yönü doğu-batı, Ka aslar kıvrım-
bindirme kuşağının uzanımı ise BKB-DGD’dur.
Anahtar Sözcükler: Ka aslar, yakınlaşan, çarpışma, Avrasya, Gondwana, volkanizma
S. ADAMIA ET AL.
491
passive continental margins – transitional zones
from ocean to continents. e Late Proterozoic–
Phanerozoic interval is divided into two stages: pre-
collisional (Late Proterozoic–Early Cenozoic) and
syn-post-collisional (Late Cenozoic). During the
pre-collisional stage, there existed environments
characteristic of modern oceanic basins and zones
transitional from ocean to continent.
Geological Provinces
Existing data allow the division of the Caucasian
region into two large-scale geological provinces:
southern Tethyan and northern Tethyan located
to the south of and to the north of the Lesser
Caucasian ophiolite suture, respectively. During the
Late Proterozoic, the Southern Province distinctly
demonstrated Pan-African (Cadomian) tectonic
events, and throughout the Palaeozoic, it was a part
of Gondwana that accumulated mainly shallow-
marine platformal sediments. In the Palaeozoic,
the Northern Province is characterized by strong
manifestation of tectonic events: supra-subduction
volcanism, granite formation, deep regional
metamorphism, deformation and orogenesis.
e Southern and Northern provinces di er each
from the other throughout the Mesozoic and Early
Cenozoic as well. e boundary between them runs
along the North Anatolian (İzmir-Ankara-Erzincan)
– Lesser Caucasian (Sevan-Akera)-Iranian Karadagh
ophiolitic suture belt (see Figure 2).
Pre-collisional Stage: Late Proterozoic-Palaeozoic
Basement Rocks
Basement rocks are represented by regionally
metamorphosed (eclogite, amphibolite, epidote-
amphibolite and greenschist facies of high, moderate,
B L A C K
S E A
G R E A T C A U C A S U S
T R A N S C A U C A S U S
CAUCASUS
LESSER
EASTERN
P O N T I D E S
ANATOLIA
L. SEVAN
L. VAN
L.URUMIYEH
CAS PIAN
S E A
P R E C A U C A S U S
IRAN
Figure 1. Physical map of the Caucasus and adjacent areas of the Black Sea-Caspian Sea region (Adamia et al.
2010).
THE GEOLOGY OF THE CAUCASUS
492
and low pressure) sedimentary, volcanic and
plutonic rocks dated according to chronological
and palaeontological data. Magmatitic rocks
are represented by two main rock complexes of
(1) ultrabasic-basic-intermediate and (2) acidic
composition. e former is a carrier of information
on the oceanic basins of Prototethys-Palaeotethys, it
outcrops within almost the all main tectonic zones of
the region (Abesadze et al. 1982), and is represented
by relatively small, dismembered, strongly deformed
and di erently metamorphosed fragments of basic
and ultrabasic rocks.
Rocks of pre-Mesozoic oceanic basins of the
region, generally, are closely associated with granite-
gneiss-magmatitic rock complexes of pre-Cambrian
MAIN TECTONIC UNITS
TECTONOSTRATIGRAPHIC UNITS (TSU)
Pc Mz
Pc Mz Kz
1
–
Sp Kz
2
Pc Kz
1
47 00’
o
Pc Pz
Alazani Fl
T a l y s h Z
Bechasin
Dz
Lo
Kh
Ah
As
Ts
Ch
La
Bu
Ka
Di
B PC- Pz
Kuban
Rioni
Terek
Aragvi
ophiolite suture belt: Sevan-Akera (SA)
Transcaucasian assif and forelands : Rioni (R) Kura (K) Alazani (Al) Aras (Ar)m its (Fd) ; ; ;
f (Fd) ; H ; ;oredeeps : Azov-Kuban Stavropol igh Terek-Caspian Gussar-Devichi
Fold-thrust mountain belts: Great Caucasus;
Achara-Trialeti; Talysh; Baiburt-Garabagh-Kaphan
Platforms: Scythian ;
Taurus-Anatolian-Central Iranian
(SC)
(TAI)
Neogene Quaternary subaerial volcanic area
–
c
a
b
pre-Cambrian-Palaeozoic basement
p- are collisional Pal eozoic of the Great Caucasus (a), Transcaucasus (b) and Lesser Caucasus (c)
p-re collisional Mesozoic
precollisional Mesozoic Early Cenozoic
–
p-re collisional Early Cenozoic
s-yn post collisional Late Cenozoic
–
Basement S
C
alients
Metamorphic omplexes
: Dzirula (Dz), Khrami (Kh),
Loki (Lo), Tsak uniats (Ts) Akhum(Ah),
Asrik hai( As).
: Chugush (Ch), Laba (La),
Buulgen (Bu),
Kassar (Ka), Dizi (Di).
,hk
-C
Gussar-Devichi Fd
Terek-Caspian Fd
Stavropol high
S c y t h i a n P l a t f o r m
Laba - Malka Z
Fore Range Z
Main Range Z
S
o u t h
e r n S
l o p e Z
S o u t h e r n S l o p e Z
Azov Kuban Fd-
Monocline Z
Daguestan Z
volcanic highlands, plateaus and extinct volcanoes: Kazbeg i (Kb), Keli (Ke)u
F or deep oreland one latform lateaud f e ; Fl f ; Z z ; Pt p ; Pl p
–––––
42 00’
o
SP Kz
2
40 00’
o
PC Kz
1
Pc Pz
Sp Kz
2
Aras Fl
Baku
Pc Mz-Kz
1
Pc -Kz
1
Sevan
Sp Kz
2
Kl
Sevan-Akera SA
Pc Mz-Kz
1
Kura
SA
Sp Kz
2
Taurus- Anatolian Central Iranian
49 00’
o
Pc Mz-Kz
1
Kura Fl
Tbilisi
Rioni Fl
A c h a r a -T r i a l e t i Z
Sp Kz
2
B PC-Pz
Grozni
Pc Mz
BPC-Pz
Pc Pz
Pc Mz-Kz
1
Pc Kz
1
42 00’
o
Pc Mz-Kz
1
Pc Mz-Kz
1
Pc Kz
1
43 00’
o
Pc Kz
1
Sp Kz
2
Pc Mz
PcMz- Kz
1
39 00’
o
41 00’
o
Novorossiisk
BLACK SEA
37 00’
o
44 00’
o
Aras
Loki - Gar abagh
Kaphan
Armenia Pl
Transcaucasian Massif TCM
42 00’
o
SP Kz
2
CASPIAN
SEA
40 00’
o
PC Kz
1
Pc Pz
Sp Kz
2
Aras Fl
Baku
Pc Mz-Kz
1
Pc -Kz
1
Sevan
Sp Kz
2
Kl
Sevan-Akera SA
Pc Mz-Kz
1
Kura
SA
Sp Kz
2
49 00’
o
Pc Mz-Kz
1
Kura Fl
Tbilisi
Rioni Fl
A c h a r a -T r i a l e t i Z
Javakheti Pl
Sp Kz
2
B PC-Pz
Pc Mz
BPC-Pz
Pc Pz
Pc Mz-Kz
1
K
Pc Kz
1
42 00’
o
Pc Mz-Kz
1
Pc Mz-Kz
1
Pc Kz
1
43 00’
o
Pc Kz
1
Sp Kz
2
Pc Mz
PcMz- Kz
1
39 00’
o
41 00’
o
BLACK SEA
37 00’
o
44 00’
o
Aras
Loki - Gar abagh
Kaphan
Armenia Pl
Transcaucasian Massif TCM
Figure 2. Tectonic map of the Caucasus (Adamia et al. 2010).
S. ADAMIA ET AL.
493
(Southern Province) and Palaeozoic (Northern
Province) basement, and represent rock associations
belonging to continental crust as well as to
transitional oceanic-continental crust. e rocks are
strongly deformed: tectonic nappes, slices, tectonic
and sedimentary mélanges (Lesser Caucasus, Dzirula
massif), accretionary prisms etc (Great Caucasus) are
frequent.
Southern Province
In the Caucasian region, the oldest, Pan-African
(Cadomian–Neo-Proterozoic) basement of the
Central Iranian platform crops out north of Erevan
(Armenia, Tsakhkuniats massif, see Figure2). It
includes two Pre-Cambrian complexes: (1) Arzacan
(ensialic) and (2) Hancavan (ensimatic).
e Arzacan ensialic complex consists of
paraschists (1500 m thick), which have undergone
metamorphism in almandine-amphibolite facies,
and of metavolcanics, phyllites, marbles, and schists
(2000 m thick) metamorphosed in greenschist facies.
e complex is intruded by granites whose Rb/Sr
isochron age is 620 Ma and crust melt isotope initial
ratio of
87
Sr/
86
Sr= 0.7102 ± 0.0006 (Agamalian 2004).
e lower unit of the Hancavan complex (1900
m thick), which during the Pan-African events was
obducted over the Arzacan complex, represents an
oceanic-crust-type assemblage and is dominated by
komatiite-basalt amphibolites with thin sedimentary
intercalations, while the upper unit (1000 m thick)
consists of metabasalt and metaandesite with beds
of marble and quartz-mica schists. Both parts of
the Hancavan complex contain tectonic lenses of
serpentinite. e complex is cut by trondhjemite
intrusions whose Rb/Sr isochron age is 685±77 Ma,
with a mantle origin ratio of
87
Sr/
86
Sr= 0.703361
(Agamalian 2004).
Boundary Between Northern and Southern Provinces
e Sevan ophiolite mélange contains di erent
exotic blocks represented by garnet-amphibolites
(Amasia – the westernmost part of the Sevan
ophiolite suture belt), amphibolites, micaschists
(Zod, Adjaris and Eranos – the eastern part of the
Sevan ophiolite suture belt) (Agamalian 2004), and
redeposited metamorphic rocks of continental
a nity: greenschists, marbles, limestones and
skarns (Geydara and Tekiakay in Karabagh Figure
3; Knipper 1991). Layers of pre-Carnian breccia-
conglomerates consisting of redeposited clasts
represented by tectonized harzburgites, layered-,
aser- and isotropic gabbros, diabases, gabbro-
diabases, altered basalts, tectonized other basic
rocks, Upper Palaeozoic marbles, basaltic andesites,
phyllites, carbonatic scarn have been found in the
ophiolite mélange of the Lesser Caucasian suture
directly to the east of the Lake Sevan (Zod and Ipiak
nappes, r. Lev-chai; Knipper 1991). Available data
show that throughout the Mesozoic at the northern
edge of Palaeotethys occured destruction and erosion
of obducted ophiolites, accumulation of redeposited
ophiolitic clastics with admixture of continental ones.
According to Agamalian (2004), the Rb/Sr
age of the Amasia amphibolites is 330±42 Ma,
87
Sr/
86
Sr= 0.7051±0.003x±0.000292. e Rb/Sr
age of a block of garnet gneiss (Zod) is equal to
296±9 Ma (
87
Sr/
86
Sr= 0.705357±0.000292), and for
metamorphic schists from the same localities 243±13
(
87
Sr/
86
Sr 0.706107±0.000156), 241±12 (
87
Sr/
86
Sr
0.707902±0.000417) and 277±44 Ma (
87
Sr/
86
Sr
0.704389±0.0003510).
e Sevan ophiolite belt represents an easternmost
part of the İzmir-Ankara-Erzincan (or North
Anatolian) ophiolite suture belt, interpreted by many
authors as the main suture of the Paleotethys-Tethys
(e.g., Adamia et al. 1977, 1981, 1987).
Northern Province: e Transcaucasian Massifs
(TCM)
Loki, Khrami, Dzirula, Akhum-Asrikchai Salients
of the Basement (see Figure 2)- All the above-
mentioned salients of the basement, except the
Akhum and Asrikchai ones, are mainly composed
of Variscian granitoids. Relatively small outcrops of
di erently tectonized and metamorphosed basic and
ultrabasic rocks are generally associated with pre-
Cambrian–Early Palaeozoic gneissose diorites and
plagiogranites.
e Loki salient outcrops in the territory of Georgia
along the boundary with Armenia, within the Artvin-
Bolnisi massif of the Transcaucasian intermontane
THE GEOLOGY OF THE CAUCASUS
494
depression. e structure of the Loki salient as well as
of the other salients of the Transcaucasian basement
seems to be more complicated than considered
earlier (Abesadze et al. 2002). Most of the salient is
composed of Upper Palaeozoic granitoids. Repeated
tectonic displacement has caused inter ngering
of metabasites and metapelites and formation of
tectonic sheets and slices (Figures 4 & 5).
e Loki basement, evidently, was formed
during the Late Proterozoic–Early Palaeozoic. e
metabasites, apparently, represent Prototethyan
fragments. e metamorphic rocks along with
11
7
6
8
4
5
160
Ma
3
2
9
1
5
0
40
80
120
160
200
240
280
320
360
400
440
m
3
8
2
1
8
8
7
3
7
5
3
5
7
4
1
3
1
1
2
2
J
1
Tc
3
a
b
c
d
e
The Ipiak nappe (a,b,c,d):
1. arzburgite tectonite;
2. ayered gabbro;
3. laser gabbro;
4. sotropic gabbro;
5. lagiogranite dyke;
6. reccia and breccia-
conglomerate consisting of
gabbro and diabase redeposited
clastics;
7. Upper Triassic Cenomanian
volcanic rocks; 8. xotic limestone
blocks; 9. iabase dykes;
10. adiolarite; 11. Upper
Cenomanian flysch.
h
l
f
i
p
b
e
d
r
–
Zod(e): 1. abbro-diabase
breccia; 2. andstone layers
consisting of gabbro-diabase
clastics; 3. asalt and basaltic
andesite; 4. Carnian: pelite and
radiolarite; 5. adiolarite;
6. Toarcian radiolarite;
7. istal turbidite and conturite;
8. locks of Carnian limestone.
T c– Carnian; J – Lower Jurassic;
K cm– Cenomanian.
g
s
b
r
d
b
31
2
Figure 3. Pre-Upper Triassic and Upper Triassic-Jurassic sedimentary breccia in the ophiolite mélange of
the Sevan-Akera suture belt (Knipper 1991).
S. ADAMIA ET AL.
495
012
3
Km
41 15’
º
44 20’
º
R.Moshevani
0
1000 2000 m
SE
2000 m
1000
-1000
0
NW
Loqjandari
Eocene volcanic formation
Bajocian island-arc type
volcanic formation
Cenomanian terrigene clastics
and island-arc type volcanic formation
ous
Lower Jurassic terrigene clasticous s
tectonic slices of metabasite
and metapelite complexes
Upper Pal eozoic granitoidsa
Lower–Middle Pal eozoic tonalite-diorite gneisses and migmatitesa
The Loki salient
faults
cross-section
Figure 4. Simpli ed geological map and cross-section of the Loki salient (Abesadze et al. 2002; Zakariadze et
al. 2007).
gneiss-migmatite complexes of the Transcaucasian
massif bear resemblance to the immature continental
crust of the Nubian-Arabian shield, and in the Early
Palaeozoic, they were displaced to the southern edge
of the East-European continent (Baltica). All the
present-day geological structures were formed in the
Late Palaeozoic–Cenozoic (Figure 4; Abesadze et al.
2002).
e Khrami salient situated to the north of the Loki
(Figure 5), is made up mainly of Upper Palaeozoic
(Variscan) granites. Plagiogneisses and migmatites
occupy a limited part and bear small bodies of
metabasites and serpentinites.
e Dzirula salient is dominated by pre-Variscan
diorite-plagiogneiss-migmatite complex (‘grey
granites’) and Variscan granit