Geochronological Evidence and Tectonic s

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Geochronological evidence and tectonic significance

of Carboniferous magmatism in the southwest Trabzon

area, eastern Pontides, TurkeyAbdullah Kaygusuz

a, Mehmet Arslan

b, Wolfgang Siebel

c, Ferkan Sipahi

a& Nurdane

Ilbeylid

aDepartment of Geological Engineering, Gmhane University, TR-29000 Gmhane,

TurkeybDepartment of Geological Engineering, Karadeniz Technical University, TR-61080 Trabzon

Turkey

cInstitute of Geosciences, Universitt Tbingen, D-72074 Tbingen, GermanydDepartment of Geological Engineering, Akdeniz University, TR-070058 Antalya, Turkey

Version of record first published: 05 Apr 2012.

To cite this article:Abdullah Kaygusuz, Mehmet Arslan, Wolfgang Siebel, Ferkan Sipahi & Nurdane Ilbeyli (2012):

Geochronological evidence and tectonic significance of Carboniferous magmatism in the southwest Trabzon area, eastern

Pontides, Turkey, International Geology Review, 54:15, 1776-1800

To link to this article: http://dx.doi.org/10.1080/00206814.2012.676371

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International Geology Review

Vol. 54, No. 15, November 2012, 17761800

Geochronological evidence and tectonic significance of Carboniferous magmatism

in the southwest Trabzon area, eastern Pontides, TurkeyAbdullah Kaygusuza*, Mehmet Arslanb , Wolfgang Siebelc , Ferkan Sipahia and Nurdane Ilbeylid

aDepartment of Geological Engineering, Gmshane University, TR-29000 Gmshane, Turkey;bDepartment of GeologicalEngineering, Karadeniz Technical University, TR-61080 Trabzon, Turkey; cInstitute of Geosciences, Universitt Tbingen, D-72074

Tbingen, Germany; dDepartment of Geological Engineering, Akdeniz University, TR-070058 Antalya, Turkey

(Accepted 12 March 2012)

The northern and southern zones of the eastern Pontides (northeast Turkey) contain numerous plutons of varying ages andcompositions. Geochemical and isotopic results on two Hercynian granitoid bodies located in the northern zone of theeastern Pontides allow a proper reconstruction of their origin for the first time. The intrusive rocks comprise four distinctbodies, two of which we investigated in detail. Based on LAICPMS UPb zircon dating, the Derinoba and Kayadibigranites have similar 206Pb/238U versus 207Pb/235U Concordia ages of 311.1 2.0 and 317.2 3.5 million years for theformer and 303.8 1.5 million years for the latter. Aluminium saturation index values of both granites are between 0.95 and

1.35, indicating dominant peraluminous melt compositions. Both intrusions have high SiO2(7477 wt.%) contents and showhigh-K calc-alkaline and I- to S-type characteristics. Primitive mantle-normalized element diagrams display enrichment in K,Rb, Th, and U, and depletion in Ba, Nb, Ta, Sr, P, and Ti. Chondrite-normalized rare earth element patterns are characterizedby concave-upward shapes and pronounced negative Eu anomalies with Lacn/Ybcn =4.69.7 and Eucn/Eu

=0.110.59

(Derinoba), and Lacn/Ybcn = 2.75.5 and Eucn/Eu= 0.310.37 (Kayadibi). These features imply crystal-melt fractionation

of plagioclase and K-feldspar without significant involvement of garnet. The Derinoba samples have initial Nd valuesbetween 6.1 and 7.1 with Nd model ages andTDMbetween 1.56 and 2.15 thousand million years. The Kayadibi samplesshow higher initial Nd(I) values, 4.5 to 6.2, with Nd model ages between 1.50 and 1.72 thousand million years. Thisstudy demonstrates that the Sr isotope ratios generally display negative correlation with Nd isotopes; Sr isotope ratios werelowered in some samples by hydrothermal interaction or alteration. Isotopic and petrological data suggest that both graniteswere produced by the partial melting of early Palaeozoic lower crustal rocks, with minor contribution from the mantle.Collectively, these rocks represent a late stage of Hercynian magmatism in the eastern Pontides.

Keywords: Carboniferous magmatism; UPb zircon dating; SrNdPb isotope; high-K; southwest Trabzon; easternPontides; Turkey

Introduction

The Pontide tectonic unit (Ketin 1966) includes various

intrusive and extrusive rocks, many of which are related

to the convergence of Eurasia and Gondwana (Figure 1A).

These Permo-Carboniferous rocks (ogulu 1975; Topuz

et al. 2004, 2010; Dokuz 2011) are present as basement

complexes in a terrane formed from the Cretaceous

Palaeocene (Ylmazet al. 2000; Boztuget al. 2006; Ilbeyli

2008; Kaygusuz et al. 2008, 2009, 2010; Kaygusuz and

Aydnakr 2009; Karsl et al. 2010; Sipahi 2011) to the

Eocene (Boztug et al. 2004; Topuz et al. 2005; Ylmaz-Sahin 2005; Arslan and Aslan 2006; Karsl et al. 2007;

Eyboglu etal. 2010, Figure 1B). Rock compositions range

from low-K through high-K calc-alkaline metaluminous

peraluminous granitoids to alkaline syenites (Ylmaz and

Boztug 1996). Igneous activity apparently occurred in

*Corresponding author. Email:[email protected]

various tectonic settings ranging from arc-collisional to

syn-collisional and post-collisional regimes (Ylmaz and

Boztug 1996; Okay and Sahintrk 1997; Ylmaz et al.

1997; Yegingilet al. 2002).

About 40% of the exposed Palaeozoic basement rocks

of the eastern Pontides are made up of granitoids. Despite

extensive exposure, these granitoids have received lit-

tle attention so far (e.g. Ylmaz 1974; ogulu 1975).

Thus, knowledge regarding Palaeozoic geological pro-

cesses in northeast Turkey is still insufficient, and precise

geochronological data are rare, thereby hampering the

understanding of the tectonic and magmatic evolution ofthis region. We report on our systematic research of two

newly mapped intrusions, the Derinoba and Kayadibi gran-

ites. New field-based observations, as well as geochemical,

geochronological, and SrNdPb isotope data from these

ISSN 0020-6814 print/ISSN 1938-2839 online

2012 Taylor & Francis

http://dx.doi.org/10.1080/00206814.2012.676371

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mailto:[email protected]:[email protected]


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International Geology Review 1777

1 2 3 4 5 6 7

Kse

40

40

Krtn

Torul

Trabzon

Maka

Gm hane pluton

Da ba

BLACK SEA

Kse plton

8

39

Tonya

9 10

B

zdil

Black Sea

Mediterranean SeaCyprus

Eurasianplate

NAFZ

Arabian plate

African plate

AegeanSea

EAFZ

DSFZ

0 200 km

42

36

39

33

4527 3933

A

Fig.2

Fig1b

N

0 5 km

Figure 1. (A) Tectonic map of Turkey and surroundings (modified after Sengret al. (2003)). (B) Distribution of plutonic and volcanicunits in the eastern Pontides (modified from Gven (1993)). (1) Palaeozoic metamorphic rocks, (2) Palaeozoic granitoids, (3) LiassicDogger volcanic rocks, (4) MalmLower Cretaceous sedimentary rocks, (5) Upper Cretaceous volcanic rocks, (6) Upper Cretaceousgranitoids, (7) Tertiary calc-alkaline volcanic rocks, (8) Tertiary alkaline volcanic rocks, (9) Eocene granitoids, (10) alluvium. NAFZ,north Anatolian fault zone; EAFZ, east Anatolian fault zone.

rocks, are presented. This study aims to gain a betterunderstanding of the regional petrogenesis and tectonicenvironment.

Geological setting and regional geology

The eastern Pontides are commonly subdivided into anorthern zone and a southern zone (Figure 2A), basedon structural and lithological features (zsayar et al.1981; Okay and Sahintrk 1997). Pre-Late Cretaceous

sedimentary rocks are widely exposed in the southernzone, whereas Late Cretaceous and middle EocenelateMiocene volcanic and volcaniclastic rocks dominate thenorthern zone (Arslanet al. 1997; Senet al. 1998; Arslanet al. 2000; Sen 2007; Temizel et al. 2012). Liassic vol-canic rocks of the eastern Pontides lie unconformably ona Palaeozoic heterogeneous crystalline basement and arecross-cut by younger granitoids of Jurassic to Palaeoceneage (Ylmaz 1972; ogulu 1975; Okay and Sahintrk 1997;Topuzet al. 2010; Dokuz 2011) (Figure 1A). Volcanic and


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1778 A. Kaygusuzet al.

Simene P

Susuzkiran H

Mandagzobasi P

Kadrga P

Sehitkitan H

Tuzlakkaya H

07

N

05

27 29 31

09

03

11

13

15

17

Kefli P

Ardiclik H

Dikenli P

Budak P

Knalk H

Bayrmahalle P

Kurban H

Davunlu H

Kizilagac P

Arpaky

0 1km

Trabzon RizeOrdu

Samsun

NAFZ

Niksar

TokatSiran

Bayburt

Artvin

Erzurum

AXIAL ZONE

TAURID PLAT

NORTHERN ZONE

SOUTHERN ZONEEAFZ

N

41

37 38 39 40 41

0 60 km

Da ba

Palaeozoic metamorp Mainly Mesozoic sedimentary rocks

Platform carbonate rocks

Undifferentiated Mesozoic and Cenozoic rocks

Serpentinite

Palaeozoic granites

Fault

Late Cretaceous and Eocene arc gran.

Cretaceous and Eocene arc volc.rocks

Thrustf.Normal fault

BLACK SEA

M41

43

M40

M43

M46

T133

T134

T136

T137

T138

T139

T140

T135

M45

M44

Kiziluzum P

Sahmetlik P

Davunlu P

Karaorman H

Dikenli H

Karaaptal H

Derinoba P

Suluk H

Pazarkiran H

Celige H

Gez H

T5N12

T1N15

M42

Palaeozoic granites

Explanation

Upper Cretaceous granitoids

Kzlkaya Formation (dacite and pyroclastics)

(Upper Cretaceous)

atak Formation (andesite and pyroclastics)

(Upper Cretaceous)

Berdiga Formation (dolomitic limestone)

(Jurassic-Lower Cretaceous)

Hamurkesen Formation (basalt,andesite and pyroclastics) (Liassic)

M16

Kayadibi

(A)

(B)

M43 Sample location

Thrust

Fault

Road

Figure 2. (A) Major structures of the eastern Pontides (modified fromEyuboglu et al. (2007)).(B) Geological map of the study areawith sample locations and main settlements.

volcano-sedimentary rocks of Early and Middle Jurassic

age are tholeiitic in character (Arslan et al. 1997; Sen

2007). These rocks are overlain conformably by Middle

Late JurassicCretaceous neritic and pelagic carbonates.

The Late Cretaceous series that unconformably overlies

these carbonate rocks is made up of sedimentary rocks

in the southern part and of volcanic rocks in the northern

part (Bektaset al. 1987; Robinsonet al. 1995; Ylmaz and

Korkmaz 1999).

Cretaceous volcanic rocks mainly belong to the tholei-

itic and calc-alkaline series. Eocene volcanic rocks uncon-

formably overlie the Late Cretaceous volcanic and/or

sedimentary series (Gven 1993; Ylmaz and Korkmaz

1999).

The altitude of the eastern Pontides (above sea level)

during the Palaeoceneearly Eocene era is attributed to

the collision between the Pontide arc and the Tauride

Anatolide platform (Okay and Sahintrk 1997; Boztug
https://www.researchgate.net/publication/228680926_Mid-Cretaceous_Olistostromal_Ophiolitic_Melange_Developed_in_the_Back-arc_Basin_of_the_Eastern_Pontide_Magmatic_Arc_Northeast_Turkey?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==https://www.researchgate.net/publication/228680926_Mid-Cretaceous_Olistostromal_Ophiolitic_Melange_Developed_in_the_Back-arc_Basin_of_the_Eastern_Pontide_Magmatic_Arc_Northeast_Turkey?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==https://www.researchgate.net/publication/228680926_Mid-Cretaceous_Olistostromal_Ophiolitic_Melange_Developed_in_the_Back-arc_Basin_of_the_Eastern_Pontide_Magmatic_Arc_Northeast_Turkey?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==https://www.researchgate.net/publication/228680926_Mid-Cretaceous_Olistostromal_Ophiolitic_Melange_Developed_in_the_Back-arc_Basin_of_the_Eastern_Pontide_Magmatic_Arc_Northeast_Turkey?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==


5/26


et al. 2004). Eocene volcanic and volcaniclastic rocks are

intruded by calc-alkaline granitoids of similar age (Arslan

and Aslan 2006; Karslet al. 2007; Eyubogluet al. 2011).

Post-Cretaceous magmatic rocks include Palaeocene plagi-

oleucitites in the southern zone (Altherret al. 2008), early

Eocene adakitic granitoids (Topuzet al. 2005), and mid-

dle to late Eocene calc-alkaline to tholeiitic, basaltic toandesitic volcanic rocks, as well as the cross-cutting gran-

itoids exposed throughout the eastern Pontides (e.g. Tokel

1977; Arslan et al. 1997; Karsl et al. 2007; Boztug and

Harlavan 2008; Temizel and Arslan 2009; Temizel et al.

2011).

The clastic input into locally developed basins is due

to post-Eocene uplift and erosion (Korkmaz et al. 1995).

Towards the end of the middle Eocene, the region is largely

above sea level. Minor volcanism and terrigeneous sedi-

mentation continues to the present (Okay and Sahintrk

1997). Miocene and post-Miocene volcanic history of the

eastern Pontides is characterized by calc-alkaline to mildly

alkaline volcanism (Aydn 2004; Ycel et al. 2011; Temizelet al. 2012).

The study area is located in the northern zone of

the eastern Pontides (Figure 1). Basement rocks consist-

ing of Palaeozoic granites (Derinoba, Kayadibi, Sahmetlik,

and Kzlaga) have been newly mapped and are being

reported for the first time in this study (Figure 2B).

The granites are unconformably overlain by Liassic vol-

canics (Figure 3A) consisting of basalts, andesites, and

their pyroclastic equivalents. These rocks are overlain

conformably by MiddleLate JurassicCretaceous carbon-

ates and Late Cretaceous volcanics. All these lithologies

are cut by Late Cretaceous granitoids.

Analytical techniques

A total of 15 samples were collected from the Derinobagranite and 5 samples from the Kayadibi granite (for sam-

ple location, see Figure 2B). Based on the petrographical

studies, 16 of the freshest and most representative rock

samples from the granites were selected for whole-rock

major, trace, and rare earth element (REE) analyses. Rock

samples were crushed in steel crushers and ground in an

agate mill to a grain size of


6/26


were mounted on epoxy resin and polished until halfway

through. Cathodoluminescence images were acquired to

check the internal structures of individual zircon grains and

to ensure a better selection of analytical positions.

UPb zircon dating was carried out using LAICP

MS at the Geologic Lab Center, China University of

Geosciences (Beijing, China). A quadrupole ICPMS(7500a; Agilent Inc., Santa Clara, CA, USA) was con-

nected with a UP-193 solid-state laser (193 nm; Electro

Scientific Industries, Inc., Portland, OR, USA) and an

automatic positioning system. The laser spot size was

set to approximately 36 m, with an energy density of

8.5 J/cm2 and repetition rate of 10 Hz. Laser sampling

was according to the following procedure: 5 s pre-ablation,

20 s sample-chamber flushing, and 40 s sampling abla-

tion. The ablated material was carried into the ICPMS

by a high-purity He gas stream with flux of 0.8 l/min.

The entire laser path was fluxed with N2 (15 l/min) and

Ar (1.15 l/min) to increase energy stability. UPb isotope

fractionation effects were corrected using zircon 91500(Wiedenbecket al. 1995) as external standard. Zircon stan-

dard TEMORA (417 million years, Blacket al. 2003) was

also used as a secondary standard to monitor the devia-

tion of age measurement/calculation. A total of 10 analyses

of TEMORA yielded apparent 206Pb/238U ages of 417 to

418 million years. Isotopic ratios and element concentra-

tions of zircons were calculated using the GLITTER soft-

ware (ver. 4.4, Macquarie University, Sydney, Australia).

Concordia ages and diagrams were obtained using

Isoplot/Ex (3.0) (Ludwig 2003). Common lead was cor-

rected following the method of Andersen (2002).

Electron microprobe analyses on polished thin sections

were carried out at the New Mexico Institute of Miningand Technology, Socorro, NM, USA, using a Cameca

SX-100 electron microprobe with three wavelength-

dispersive spectrometers. Samples were examined using

backscattered electron imagery, and selected minerals were

quantitatively analysed. Elements analysed included F, Na,

Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Sr, and Ba.

An accelerating voltage of 15 kV and probe current of

20 nA were used, except for analyses using general glass

labels (i.e. chlorite), which utilized a 10 nA probe current.

Peak count numbers of 20 s were used for all elements,

except for F (40 s; amph/mica), F (60 s; glass), Cl (40 s), S

(30 s), Sr (60 s), and Ba (60 s). Background count numbers

were one half the peak count times. A point beam of 1 m

was used to analyse amphibole, pyroxene, epidote, FeTi

oxide, and zircon. A slightly defocused (10 m) beam was

used to analyse feldspar, mica, and chlorite to avoid losses

caused by sodium volatilization (Nielsen and Sigurdsson

1981). Analytical results are presented in Tables 13.

Sr, Nd, and Pb isotope compositions were measured on

a Finnigan MAT 262 multicollector mass spectrometer at

the Institute of Geosciences, Tbingen, Germany. For Sr

Nd isotope analyses, approximately 50 mg of whole-rock

powder was decomposed in 52% HF for 4 days at 140C

on a hot plate. Digested samples were dried and redis-

solved in 6 N HCl; these were dried again and redissolved

in 2.5 N HCl. Sr and Nd were separated by conventional ion

exchange techniques, and their isotopic compositions were

measured on single W and double Re filament configura-

tions, respectively. The isotopic ratios were corrected forisotopic mass fractionation by normalizing to 86 Sr/88Sr=

0.1194 and146Nd/144Nd= 0.7219. The reproducibility of87Sr/86Sr and143Nd/144Nd during the period of measure-

ment was checked by analyses of NBS 987 Sr and La Jolla

Nd standards, which yielded average values of 0.710235

0.000015 (2SD,n = 3) and 0.511840 0.000008 (2SD,

n = 5), respectively. Total procedural blanks were 2050 pg

for Sr and 4066 pg for Nd. The separation and purifi-

cation of Pb were carried out on Teflon columns with a

100 m (separation) and 40 m bed (cleaning) of Bio-

Rad AG1-X8 (100200 mesh) anion exchange resin using

an HBrHCl ion exchange procedure. Pb was loaded with

Si-gel and phosphoric acid into a Re filament and wasanalysed at about 1300C in a single-filament mode. A fac-

tor of 1 per atomic mass unit for instrumental mass

fractionation was applied to the Pb analyses, using NBS

SRM 981 as reference material. The total procedural blanks

for Pb during the measurement period were between 20 and

40 pg. Sample reproducibility was estimated at 0.02,

0.015, and0.03 (2) for206Pb/204Pb, 207Pb/204Pb, and208Pb/204Pb ratios, respectively.

Results

Field relations and petrography

The resulting geological map contains four separate gran-

ite bodies, namely, Derinoba, Kayadibi, Sahmetlik, and

Kzlaga (Figure 2B). These intrusions form nearly NE

SW-elongated bodies in varying dimensions occupying

the highest peaks in the region. Generally, these are

bounded by the pre-Jurassic volcanic and pyroclastic

rocks to the east. Liassic volcanic and pyroclastic rocks

(Hamurkesen Formation) unconformably overlie the gran-

ite bodies (Figure 3A). In the west, granite bodies thrust

over Late Cretaceous volcanic and pyroclastic rocks (atak

and Kzlkaya Formations).

The Derinoba granite, located about 65 km southwest

of Trabzon, forms an EW-elongated body, with the longaxis extending from northeast to southwest (Figure 2B).

This granite body covers an area of approximately 13 km 2.

In the east, the granite is unconformably overlain by

Lower Jurassic volcanic and pyroclastic rocks, whereas

in the west, the granite thrusts over Late Cretaceous vol-

canic and pyroclastic rocks together with their cover rocks

(Figure 2B). The Derinoba granite is generally unde-

formed, but strongly altered and weathered. Rocks often

have a brick red to pink colour, except for strongly chlori-

tized zones that are greenish.


7/26


Table1.

Microprobeanalyseso

fplagioclasesfromtheDerinobaandKaya

dibigranites.

Plagioclase

Rock

types

Derinobagranites

Kayadibigranites

Samples

T138-3c

T138-4rT138-5c

T138-6rT138-11c

T138-12rT135-1

rT135-2c

T135-7rT135-8c

T135-9rT

135-10c

M16-3c

M16-4c

M16-5c

M16-6rM16-9c

M16-10c

SiO2

68.0

9

68.1

6

68

.88

68.9

8

65.7

4

68.4

9

68.48

67.2

6

67.5

1

65.7

3

67.4

9

67.4

1

67.5

6

66.8

0

66.3

3

68.2

1

67.3

0

67.5

1

Al2O3

20.7

4

19.8

3

20

.31

20.4

1

22.3

7

21.0

9

20.02

21.4

1

20.3

0

21.3

9

19.5

6

20.2

7

20.6

7

20.6

8

21.0

5

20.9

7

21.1

7

20.8

0

FeOT

0.0

6

0.0

9

0

.14

0.0

3

0.2

8

0.0

5

0.04

0.2

3

0.0

5

0.2

5

0.0

6

0.1

4

0.0

5

0.1

4

0.0

8

0.0

9

0.1

1

0.0

8

CaO

0.7

7

0.2

7

0

.30

0.1

4

0.6

2

0.8

7

0.19

0.2

8

0.4

1

0.5

5

0.2

0

0.2

7

0.5

6

1.1

6

0.6

6

0.8

4

1.2

3

0.6

5

Na2O

11.3

2

11.1

6

11

.71

11.6

0

10.2

5

11.4

6

11.62

10.9

7

11.2

5

10.5

1

11.2

4

11.3

6

11.4

0

11.0

7

10.8

2

11.3

4

11.1

5

11.2

5

K2O

0.1

0

0.1

1

0

.10

0.1

1

1.1

8

0.3

1

0.14

0.9

0

0.2

7

1.0

8

0.1

3

0.4

0

0.2

3

0.2

8

0.6

0

0.1

6

0.1

7

0.2

3

BaO

0.0

2

0.0

6

0

.07

0.0

0

0.0

3

0.0

2

0.00

0.0

9

0.0

0

0.0

0

0.0

0

0.1

0

0.0

0

0.0

2

0.0

3

0.0

5

0.0

3

0.0

5

SrO

0.0

3

0.0

2

0

.01

0.0

2

0.0

6

0.0

7

0.05

0.0

2

0.0

0

0.0

5

0.0

0

0.0

4

0.0

3

0.0

4

0.0

3

0.0

2

0.0

0

0.0

5

Total

101.1

99.7

101

.5

101.3

100.5

102.4

100.5

101.2

99.8

99.5

98.7

100.0

100.5

100.2

99.6

101.7

101.2

100.6

Cationsonthebasisofeightoxygens

Si

2.9

5

2.9

9

2

.97

2.9

7

2.8

8

2.9

4

2.98

2.9

2

2.9

6

2.9

1

2.9

9

2.9

6

2.9

5

2.9

3

2.9

2

2.9

4

2.9

2

2.9

4

Al

1.0

6

1.0

2

1

.03

1.0

4

1.1

5

1.0

7

1.03

1.1

0

1.0

5

1.1

1

1.0

2

1.0

5

1.0

6

1.0

7

1.0

9

1.0

7

1.0

8

1.0

7

Fe2+

0.0

0

0.0

0

0

.01

0.0

0

0.0

1

0.0

0

0.00

0.0

1

0.0

0

0.0

1

0.0

0

0.0

0

0.0

0

0.0

1

0.0

0

0.0

0

0.0

0

0.0

0

Ca

0.0

4

0.0

1

0

.01

0.0

1

0.0

3

0.0

4

0.01

0.0

1

0.0

2

0.0

3

0.0

1

0.0

1

0.0

3

0.0

5

0.0

3

0.0

4

0.0

6

0.0

3

Na

0.9

5

0.9

5

0

.98

0.9

7

0.8

7

0.9

5

0.98

0.9

2

0.9

6

0.9

0

0.9

6

0.9

7

0.9

6

0.9

4

0.9

2

0.9

5

0.9

4

0.9

5

K

0.0

1

0.0

1

0

.01

0.0

1

0.0

7

0.0

2

0.01

0.0

5

0.0

1

0.0

6

0.0

1

0.0

2

0.0

1

0.0

2

0.0

3

0.0

1

0.0

1

0.0

1

Ba

0.0

0

0.0

0

0

.00

0.0

0

0.0

0

0.0

0

0.00

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

Sr

0.0

0

0.0

0

0

.00

0.0

0

0.0

0

0.0

0

0.00

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

Total

5.0

0

4.9

9

5

.01

4.9

9

5.0

1

5.0

2

5.00

5.0

2

5.0

0

5.0

2

4.9

9

5.0

1

5.0

1

5.0

1

5.0

1

5.0

1

5.0

1

5.0

1

An

3.5

8

1.3

0

1

.40

0.6

5

3.0

0

3.9

7

0.87

1.3

0

1.9

5

2.6

1

0.9

6

1.2

5

2.6

1

5.4

0

3.1

4

3.9

1

5.7

1

3.0

4

Ab

95.8

4

98.0

8

98

.06

98.7

6

90.1

7

94.3

7

98.33

93.6

3

96.5

4

91.2

2

98.3

2

96.5

3

96.1

1

93.0

5

93.4

4

95.2

3

93.3

5

95.6

8

Or

0.5

8

0.6

2

0

.53

0.5

9

6.8

3

1.6

6

0.80

5.0

8

1.5

1

6.1

7

0.7

2

2.2

2

1.2

8

1.5

5

3.4

3

0.8

6

0.9

4

1.2

8

Note:FeOTistotalironasFeO;r,rimofc

rystal;c,coreofcrystal.


8/26


Table2.

Microprobeanalyseso

fK-feldsparsfromtheDerinobaandKayadibigranites.

K-feldspar

Rock

types

Derinobagranites

Kayadibigranites

SamplesT138-1cT138-2rT138-14cT138-15rT138-19cT138-20

rT135-3rT135-4cT135-5rT135-6cT135-11rT135-12rM16-1cM16-2

rM16-7rM16-8c

SiO2

64.6

2

64.7

1

64.2

7

65.2

5

63.8

5

63.70

63.9

9

63.9

1

63.9

1

63.7

8

63.3

0

64.0

6

63.8

8

64.03

64.3

8

64.1

9

Al2O3

18.9

9

18.8

6

18.8

4

19.1

8

19.1

7

19.20

18.5

5

18.5

1

18.5

9

18.8

2

18.3

1

18.8

1

18.6

9

18.77

18.8

3

18.6

1

FeOT

0.0

4

0.0

5

0.0

4

0.0

0

0.0

1

0.02

0.0

4

0.0

8

0.0

1

0.0

5

0.0

0

0.0

4

0.0

0

0.04

0.1

0

0.0

7

CaO

0.0

2

0.0

5

0.0

0

0.0

3

0.0

1

0.60

0.0

0

0.0

1

0.0

0

0.0

2

0.0

2

0.0

5

0.0

0

0.01

0.0

0

0.0

0

Na2O

0.3

0

0.4

0

0.0

0

0.6

1

0.2

6

0.29

0.6

9

0.5

3

0.3

5

0.6

3

0.3

4

0.4

3

0.3

6

0.31

0.4

3

0.4

7

K2O

16.1

9

15.8

4

16.4

8

15.9

1

16.1

3

16.18

16.0

9

16.2

0

16.4

7

16.0

0

16.2

3

16.3

1

16.5

0

16.51

16.5

2

16.4

9

BaO

0.1

8

0.2

1

0.2

0

0.2

1

1.1

3

0.09

0.1

6

0.2

3

0.3

9

0.4

9

0.0

0

0.4

3

0.3

3

0.16

0.1

4

0.0

5

SrO

0.0

0

0.0

2

0.0

1

0.0

2

0.0

5

0.01

0.0

2

0.0

0

0.0

0

0.0

6

0.0

3

0.0

5

0.0

1

0.02

0.0

1

0.0

2

Total

100.3

100.1

99.8

101.2

100.6

100.1

99.5

99.5

99.7

99.8

98.2

100.2

99.8

99.9

100.4

99.9

Cationsonthebasisofeightoxygens

Si

2.9

8

2.9

8

2.9

8

2.9

8

2.9

6

2.95

2.9

8

2.9

8

2.9

8

2.9

7

2.9

8

2.9

7

2.9

7

2.97

2.9

7

2.9

8

Al

1.0

3

1.0

3

1.0

3

1.0

3

1.0

5

1.05

1.0

2

1.0

2

1.0

2

1.0

3

1.0

2

1.0

3

1.0

3

1.03

1.0

3

1.0

2

Fe

2+

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.00

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.00

0.0

0

0.0

0

Ca

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.03

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.00

0.0

0

0.0

0

Na

0.0

3

0.0

4

0.0

0

0.0

5

0.0

2

0.03

0.0

6

0.0

5

0.0

3

0.0

6

0.0

3

0.0

4

0.0

3

0.03

0.0

4

0.0

4

K

0.9

5

0.9

3

0.9

7

0.9

3

0.9

5

0.96

0.9

6

0.9

6

0.9

8

0.9

5

0.9

8

0.9

7

0.9

8

0.98

0.9

7

0.9

8

Ba

0.0

0

0.0

0

0.0

0

0.0

0

0.0

2

0.00

0.0

0

0.0

0

0.0

1

0.0

1

0.0

0

0.0

1

0.0

1

0.00

0.0

0

0.0

0

Sr

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.00

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

0

0.00

0.0

0

0.0

0

Total

4.9

9

4.9

9

4.9

9

5.0

0

5.0

1

5.02

5.0

2

5.0

2

5.0

2

5.0

2

5.0

1

5.0

2

5.0

2

5.01

5.0

2

5.0

2

An

0.0

8

0.2

4

0.0

1

0.1

7

0.0

4

2.95

0.0

2

0.0

5

0.0

0

0.1

1

0.1

2

0.2

7

0.0

1

0.04

0.0

2

0.0

0

Ab

2.7

5

3.6

5

0.0

0

5.4

9

2.3

8

2.56

6.1

4

4.7

5

3.1

3

5.6

7

3.0

6

3.8

2

3.1

9

2.81

3.8

3

4.1

2

Or

97.1

7

96.1

1

99.9

9

94.3

4

97.5

8

94.50

93.8

4

95.2

0

96.8

7

94.2

1

96.8

2

95.9

2

96.8

0

97.15

96.1

5

95.8

8

Note:FeO

TistotalironasFeO;r,rim

ofcrystal;c,coreofcrystal.


9/26


Table 3. Microprobe analyses of biotites from the Derinoba and Kayadibi granites.

Biotite

Rock types Derinoba granites Kayadibi granites

Samples T135-1 T135-2 T138-1 T138-2 M16-1 M16-2 T5-1 T5-2SiO2 35.47 36.36 36.58 37.79 35.90 36.10 36.11 37.10

TiO2 4.65 3.94 3.87 3.25 4.74 4.00 3.55 3.41Al2O3 13.52 13.11 12.96 13.36 12.78 13.12 13.34 13.20Cr2O3 0.01 0.00 0.01 0.01 0.00 0.02 0.01 0.00FeOT 23.18 24.73 24.94 21.25 23.42 24.43 24.64 22.50MnO 0.35 0.34 0.27 0.28 0.38 0.38 0.29 0.26MgO 10.01 11.25 9.25 10.31 11.76 11.44 11.43 10.62CaO 0.02 0.04 0.02 0.03 0.03 0.01 0.02 0.02Na2O 0.12 0.11 0.12 0.13 0.16 0.09 0.11 0.10K2O 8.24 7.42 8.08 9.06 8.30 8.32 8.02 8.74Total 95.57 97.30 96.10 95.47 97.47 97.91 97.52 95.95

Cations on the basis of 22 oxygensSi 5.50 5.54 5.66 5.80 5.47 5.49 5.51 5.70Ti 0.54 0.45 0.45 0.37 0.54 0.46 0.41 0.39Al 2.47 2.35 2.37 2.42 2.29 2.35 2.40 2.39Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Fe2+ 3.00 3.15 3.23 2.72 2.98 3.10 3.14 2.89Mn 0.05 0.04 0.04 0.04 0.05 0.05 0.04 0.03Mg 2.31 2.55 2.14 2.36 2.67 2.59 2.60 2.43Ca 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00Na 0.04 0.03 0.04 0.04 0.05 0.03 0.03 0.03K 1.63 1.44 1.60 1.77 1.61 1.61 1.56 1.71Total 15.55 15.57 15.52 15.53 15.67 15.69 15.68 15.58

Mg/Mg+ Fe2+ 0.44 0.45 0.40 0.46 0.47 0.46 0.45 0.46Fe2+/Fe2+ +Mg 0.56 0.55 0.60 0.54 0.53 0.54 0.55 0.54

Note: FeOT is total iron as FeO.

The Kayadibi granites, as well as the two other stocks

referred to as Sahmetlik and Kzlaga, form small ellip-

tical bodies. Each of these bodies has an outcrop area ofapproximately 1 km2 (Figure 2A), overlain unconformably

by Lower Jurassic volcanic and pyroclastic rocks in the

east and thrust over Late Cretaceous volcanic and pyroclas-

tic rocks in the west (Figure 2A). All granites mentioned

are cut by Late Cretaceous granites and dacitic dikes and

domes (Figure 3B).

Studied samples (i.e. obtained from Derinoba and

Kayadibi) are medium- to coarse-grained monzogran-

ites, share several common petrographic features, and

are described together. These samples are composed of

equigranular K-feldspar, quartz, plagioclase, biotite, acces-

sory zircon, apatite, allanite, magnetite, and secondary

phases of sericite, chlorite, epidote, clay minerals, carbon-ates, and white mica (Figures 3C and 3D).

Plagioclase forms subhedral to euhedral, normally and

reversely zoned prismatic crystals. In some samples, it

is altered into sericite and clay minerals and partly into

epidote. Representative mineral analyses of plagioclase

crystals are provided in Table 1. Composition in all samples

is pure albite and varies from An1 to An4 in the Derinoba

granite, whereas in the Kayadibi granite, it is slightly less

rich in sodium and ranges from An3 to An6. K-feldspar

forms anhedral, rarely subhedral crystals of orthoclase and

perthitic orthoclase. Large K-feldspar oikocrysts contain

inclusions of abundant plagioclase, biotite, and opaqueminerals. Representative mineral analyses of K-feldspar

are presented in Table 2. Compositions range from Or94to Or99 in the Derinoba granite and Or96 to Or97 in the

Kayadibi granite (Table 2).

Biotite is euhedral to subhedral, is reddish-brown in

colour, and forms small prismatic crystals and lamel-

las. In most samples, biotite is strongly chloritized

or partially replaced by prehnite and/or pumpellyite.

Biotite sheets are frequently deformed around secondary

prehnite/pumpellyite grains. Primary inclusions in biotite

are magnetite, apatite, and zircon. Representative biotite

analyses are provided in Table 3. The Mg-number (Mg/Mg

+ Fe2+) varies from 0.40 to 0.46 in the Derinoba graniteand from 0.45 to 0.47 in the Kayadibi granite (Table 3).

TiO2contents are relatively high (3.254.74 wt.%).

Quartz is anhedral in shape and generally shows undu-

lose extinction. It locally forms large grains but also fills

the interstitial spaces left behind from early-crystallized

plagioclase and mafic minerals.

Apatite is the most common accessory mineral and

occurs as small prismatic and acicular crystals. Allanite

forms euhedral, reddish crystals in all samples. Zircon is


10/26


observed as short euhedral and prismatic crystals. Opaque

minerals are mostly titaniferous magnetites that occur as

phenocrysts and microphenocrysts.

Whole-rock chemistry

Major, trace, and REE analyses of representative sam-

ples from the Derinoba and Kayadibi granites are given

in Table 4. In the classification diagram of Debon and Le

Fort (1982), all samples are plotted in the granite field

(Figure 4A). In the RbSrBa ternary diagram (Tarney and

Jones 1994), samples are plotted in the field of low BaSr

granitoids (not shown here).

Both granites span a narrow compositional range

(Table 4, Figure 4A). SiO2 ranges from 75 to 77 wt.%

in the Derinoba granite and from 74 to 75 wt.% in the

Kayadibi granite (Table 4). K2O/Na2O ratios vary between

0.98 and 1.45 (Derinoba) and 1.18 and 1.43 (Kayadibi).

The aluminium saturation index (ASI) (molar Al2O3/(CaO+ Na2O + K2O)) values of samples from the Derinoba

and Kayadibi granites are between 0.95 and 1.35, with

an average of 1.14. These figures indicate that the gran-

ites are dominantly peraluminous (Table 4, Figure 4B).

Both granites show subalkaline affinity and belong to the

high-K calc-alkaline series (Figure 5A). In the SiO2 ver-

sus ASI diagram (Figure 5B), the samples are plotted in

the I- to S-type granite fields. Some altered samples from

the Derinoba granite portray elevated ASI values. Harker

plots of selected major and trace elements (Figure 5C

5R) show systematic variations in element concentration.

The rocks define trends without a compositional gap. CaO,

MgO, Fe2O3(T), TiO2, P2O5, Ba, Sr, Th, Ni, and Y con-

tents decrease with increasing SiO2content, whereas K2O,

Al2O3, Zr, and Nb increase with increasing SiO2 content;

Na2O and Pb are nearly constant (Figure 5C5R).

In the primitive mantle-normalized trace element dia-

grams (Figure 6A6C), all samples from the Kayadibi and

Derinoba granites display marked negative anomalies in

Ba, Nb, Ta, Sr, P, and Ti, but positive anomalies in K

and partly Pb, which indicate fractionation of plagioclase,

K-feldspar, biotite, apatite, and FeTi oxides.

Chondrite-normalized REE patterns of the Kayadibi

and Derinoba granite samples (Figure 6D6F) are gener-

ally characterized by concave-upward shapes (Lacn/Ybcn= 2.79.7) and pronounced negative Eu anomalies

(Eucn/Eu) of 0.110.59, whereas the largest Eu-anomalies

appear in the Derinoba granite (Table 4). Compared

with other Palaeozoic granitoids of the eastern Pontides

(Figure 6C and 6F), the trace and REE patterns of the

Derinoba and Kayadibi granites resemble those of the

Gmshane pluton (Topuz et al. 2010). However, the

Derinoba and Kayadibi granites differ from the Gmshane

pluton in terms of the stronger negative Eu anomalies

(Figure 6F).

In the (Zr+ Nb + Ce + Y) versus FeO/MgO tec-

tonic discrimination diagram of Whalen et al. (1987), the

Derinoba and Kayadibi granites fall within the I-type gran-

ite field (Figure 7A). Furthermore, the tectonic discrimina-

tion diagram ofBatchelor and Bowden (1985)(Figure 7B)

suggests a syn- to post-collisional geochemical signature

for both granites.

SrNdPb isotopes

Sr, Nd, and Pb isotope data for the Kayadibi and Derinoba

granites are given in Tables 5 and 6 and plotted in Figure 8.

Initial Sr, Nd, and Pb isotope ratios are calculated using

Rb, Sr, Sm, Nd, U, Th, and Pb concentration data obtained

from ICPAES and MS analyses, with the assumed granite

ages of 303 million years (Kayadibi) and 317311 million

years (Derinoba) (see below). Samples from the Kayadibi

and Derinoba granites show a relatively wide range of ini-

tial87

Sr/86

Sr ratios (0.69740.7079) and a narrow range ofNd(I) values (4.6 to 7.1). The corresponding Nd model

ages (TDM) of the granites are in the range 1.502.15 thou-

sand million years. Extremely low (87Sr/86Sr)(I) ratios

(0.69740.7003) are found in samples, showing evidence

for alteration, which may suggest that the RbSr system

is more severely influenced by hydrothermal alteration or

weathering than the SmNd isotope system.

No correlation exists betweenNd(I) and (87Sr/86Sr)(I)

but the Derinoba samples display lower Nd(I) val-

ues (7.1 to 6.1) and higher (87Sr/86Sr)(I) ratios

(0.70030.7079) than the Kayadibi samples [Nd(I) =

4.6 to 6.2, (87Sr/86Sr)(I) =0.69740.703] (Figure 8A).

In the SiO2versus (87Sr/86Sr)(I) and (143Nd/144Nd)(I)dia-grams (Figures 8B and 8C), the samples define nearly

horizontal trends, indicating fractional crystallization.

A slightly positive correlation, however, is shown in the

(143Nd/144Nd)(I)versus Nd plot (Figure 8D).

In Figure 8A, the Derinoba and Kayadibi granites

are compared with other Palaeozoic granites from the

eastern Pontides. As shown in this plot, the studied sam-

ples have similarNd(I) and (87Sr/86Sr)(I) ratios to those

from Gmshane pluton but lower (87Sr/86Sr)(I)ratios than

those of the Kse pluton. The Kse samples show a nega-

tive correlation betweenNd(I) and (87Sr/86Sr)(I), whereas

the Kayadibi, Derinoba, and Gmshane samples show no

obvious correlation between these two parameters.Samples from the Kayadibi and Derinoba granites have

similar (207Pb/204Pb)(I) = 15.5515.62, but have vari-

able (206Pb/204Pb)(I) = 17.2918.0 and (208Pb/204Pb)(I) =

36.3837.67 isotopic compositions (Table 6, Figures 8E

and 8F). In the (207Pb/204Pb)(I) versus (206Pb/204Pb)(I)

diagram (Figure 8E), the samples are plotted to the left

of the geochron and above the Northern Hemisphere

Reference Line (Hart 1984). In the (206Pb/204Pb)(I) versus

(207Pb/204Pb)(I) diagram (Figure 8F), the studied samples
https://www.researchgate.net/publication/228524545_Carboniferous_high-potassium_I-type_granitoid_magmatism_in_the_Eastern_Pontides_The_Gumushane_pluton_NE_Turkey?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==https://www.researchgate.net/publication/228524545_Carboniferous_high-potassium_I-type_granitoid_magmatism_in_the_Eastern_Pontides_The_Gumushane_pluton_NE_Turkey?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==https://www.researchgate.net/publication/228524545_Carboniferous_high-potassium_I-type_granitoid_magmatism_in_the_Eastern_Pontides_The_Gumushane_pluton_NE_Turkey?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==https://www.researchgate.net/publication/248358667_Petrogenetic_interpretation_of_granitoid_rock_series_using_multicationic_parameters_Chem_Geol_48_43-55?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==https://www.researchgate.net/publication/248358667_Petrogenetic_interpretation_of_granitoid_rock_series_using_multicationic_parameters_Chem_Geol_48_43-55?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==https://www.researchgate.net/publication/228524545_Carboniferous_high-potassium_I-type_granitoid_magmatism_in_the_Eastern_Pontides_The_Gumushane_pluton_NE_Turkey?el=1_x_8&enrichId=rgreq-50835883-ef5a-4fad-a4ad-11e2c9f99369&enrichSource=Y292ZXJQYWdlOzI0MTcxMzAzNztBUzoyMTgwMjE1NjI5ODI0MDFAMTQyODk5MTc5OTkxOA==


11/26


12/26


Tab

le4

.

(Con

tinued

).

Roc

ktypes

Der

ino

bagranite

s

Kayad

ibigran

ites

Samp

les

T135

M42

T138

T137

T140

M43

M45

T136

T134

M40

M41

T1

N15

T5

N12

M16

Dy

6.2

3

6.8

5

6.4

5

6.2

4

3.3

9

5.5

8

4.2

0

4.5

0

4.9

7

3.2

5

3.4

1

7.2

1

6.0

2

6.7

3

6.0

6

6.0

4

Ho

1.7

0

1.7

5

1.6

5

1.7

1

0.7

5

1.1

1

1.2

6

1.3

3

0.9

9

0.7

4

0.7

7

1.6

4

1.4

6

1.3

5

1.5

2

1.4

5

Er

4.7

3

3.9

8

4.7

6

3.1

0

2.3

3

3.2

2

3.1

8

3.1

0

2.9

7

2.2

4

2.3

8

4.6

8

4.2

6

4.2

0

4.8

6

4.5

4

Tm

0.4

3

0.5

8

0.7

1

0.6

2

0.3

7

0.4

9

0.5

2

0.5

0

0.4

5

0.3

6

0.3

9

0.5

7

0.6

2

0.6

5

0.7

1

0.7

8

Yb

3.9

0

3.9

5

4.3

3

4.2

0

2.5

4

3.0

6

3.1

0

3.1

5

2.9

2

2.5

4

2.5

9

4.8

3

4.6

2

4.4

9

4.6

5

4.5

7

Lu

0.5

6

0.5

0

0.5

8

0.5

2

0.3

8

0.4

6

0.4

4

0.4

7

0.4

3

0.3

6

0.3

9

0.6

8

0.6

1

0.6

2

0.6

4

0.5

3

Lac

n/Lu

cn

4.8

8

6.3

0

5.5

9

6.8

5

7.5

5

9.0

9

7.1

3

7.6

4

8.7

4

9.2

0

9.8

8

2.9

1

3.7

0

6.1

3

6.0

3

7.0

9

Lac

n/Sm

cn

3.4

3

3.8

9

3.4

2

4.0

9

3.5

2

3.8

2

3.6

0

4.0

2

4.5

1

3.9

1

4.9

3

1.8

6

2.6

4

3.7

9

3.6

1

4.0

5

Gd

cn

/Lu

cn

1.6

4

1.1

7

1.3

7

1.5

1

0.9

5

1.5

5

1.3

7

1.1

4

1.5

0

0.8

3

0.7

9

1.5

8

1.6

7

1.2

7

1.4

2

1.6

7

Lac

n/Yb

cn

4.5

7

5.2

0

4.8

8

5.5

3

7.3

7

8.9

2

6.6

0

7.4

4

8.4

0

8.5

1

9.7

1

2.6

7

3.1

9

5.5

2

5.4

2

5.3

7

Tb

cn

/Yb

cn

1.7

0

1.4

3

1.4

0

1.2

6

0.9

8

1.4

0

1.3

2

1.0

6

1.3

2

0.8

9

0.9

2

1.2

7

1.2

2

1.2

2

1.1

5

1.1

4

Eu

cn

/Eu

0.4

3

0.5

9

0.5

1

0.4

8

0.2

4

0.4

1

0.3

8

0.3

4

0.4

4

0.1

1

0.1

1

0.3

4

0.3

4

0.3

4

0.3

7

0.3

1

Mg

#

22

.58

19

.63

22

.22

23

.66

32

.52

29

.63

22

.86

13

.20

24

.68

9.3

2

10

.49

22

.64

20

.67

18

.18

24

.57

19

.87

ASI

1.1

2

1.1

0

0.9

8

1.0

7

1.2

6

1.2

2

1.2

2

1.1

7

1.1

8

1.3

5

1.3

0

1.1

5

1.0

7

0.9

5

1.0

2

1.0

9

K2

O/Na2

O

1.0

0

1.2

8

1.1

2

1.1

9

0.9

8

1.1

1

1.3

2

1.4

5

1.1

2

1.3

7

1.3

8

1.2

1

1.1

8

1.4

3

1.2

4

1.2

4

Rb/Sr

1.8

5

2.1

1

2.8

9

2.9

3

1.7

5

2.4

1

2.4

7

2.4

2

3.6

1

5.0

1

5.1

9

0.5

2

1.0

6

1.7

8

1.7

2

2.0

2

Sr/

Y

2.2

2

1.8

4

1.2

0

1.3

3

3.2

4

1.3

6

1.4

2

1.5

8

1.3

0

1.7

5

1.6

9

3.7

0

1.9

1

1.5

9

2.0

2

1.4

8

Nb/Ta

13

.22

12

.50

12

.91

15

.89

8.1

7

14

.60

15

.33

12

.27

15

.22

5.6

7

6.7

6

20

.50

14

.00

10

.40

12

.36

12

.69

Zr/

Hf

24

.33

24

.58

25

.33

28

.07

26

.29

31

.25

26

.38

34

.55

30

.32

47

.60

51

.41

27

.35

28

.79

28

.63

28

.69

24

.92

Th/U

4.7

3

4.5

0

4.3

4

4.4

4

6.7

7

5.4

8

5.4

3

5.1

7

5.3

7

2.4

8

2.5

9

13

.80

7.0

0

3.4

9

4.9

5

5.8

6

No

te:

Fe2

OT 3istotalironas

Fe2

O3;

LOIislosson

ign

ition;

Mg

#(Mg-n

um

ber

)=1

00

Mg

O/(Mg

O+

Fe2

OT 3);ASI=

mo

lar

Al

2O

3/(CaO+

Na2

O+

K2

O);Eu=

(Smcn+G

dcn

)/2;

(Lacn

/Lucn

)=

chon

dri

te-n

orma

lized

La/

Lura

tio

,ox

idesareg

iven

inw

t.%

,traceelemen

tsinppm;

ASI,alum

iniumsa

tura

tion

index

.


13/26


40 50 60 70 80 90

SiO2(wt%)

0

5

10

15

Na2O

+K2O(wt%)

Suba

lkalin

eseries

Gabbro

Gabbroic

Diorite

Diorite

Tonalite

Granodiorite

GraniteMnzgbr

Mnzdi

Monzonit Qmonz

Syenite

Peridot

Gabbro

Foidgabbro

Foidmonzosyenite

Foidolit

Foidmonzogabbro

Quartzolite

(A)

Derinobagr.Kayadibigr.

0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5

A/CNK

0.7

0.8

0.91.0

1.1

1.2

1.3

1.4

1.5

A/NK

Peraluminous

Metaluminous

(B)

Peralkaline

Aluminous

Figure 4. (A) Chemical nomenclature diagram (Debon and Le Fort 1982) for samples from the Derinoba and Kayadibi granites. (B)A/CNK (Al2O3/CaO + Na2O + K2O) versus A/NK (Na2O + K2O) molar diagram showing the range in alumina saturation index (ASI)of Derinoba and Kayadibi granites.

form subparallel trends to the orogen curve (Zartman and

Doe 1981).

UPb zircon dating

LAICPMS UPb zircon dating results are presented in

Table 7 and shown in Concordia diagrams (Figure 9).

Zircons are colourless to light yellow, with long prismatic,

perfectly euhedral, and oscillatory zoning (Figure 10).

Zircon grains are mostly fine-grained (63125 m) and

have aspect ratios of about 1:3. Inclusions of apatite and

internal fractures are common. All these features indicate

that zircons are of magmatic origin. Some grains are cor-

roded and display altered domains. Only the uncorroded

inner parts of the grains are investigated for UPb isotopeanalyses. Most analyses give concordant age data. A total

of 23 spots from sample T138 (Derinoba) yield206 Pb/238U

ages ranging from 301 to 317 million years, with a

weighted mean age of 311.1 2.0 million years (MSWD=

1.4) (Table 7, Figure 9A), and 12 spots from another sam-

ple of this granite (T135) give 206Pb/238U ages between

310 and 325 million years, with a weighted mean age of

317.2 3.5 million years (MSWD = 1.7) (Figure 9B).

A total of 30 spots from sample M16 (Kayadibi) provide206Pb/238U ages between 300 and 306 million years, with a

weighted mean age of 303.8 1.5 million years (MSWD=

0.119) (Figure 9C). Thus, Lower Carboniferous ages are

established for both granites by UPb zircon dating, and

these ages are interpreted as magmatic emplacement ages.

Discussion

Age constraints

In previous works, the emplacement age of granitoids

in the eastern Pontides is mainly estimated from contact

relationships, stratigraphic criteria, or biostratigraphic data.

Such data, however, are often imprecise or difficult to

obtain due to rock deformation or tectonic displace-

ment. Thus, an age reassessment, in the light of new

geochronological data, is essential. Early geochronologicstudies on the Gmshane and Kse plutons, however,

have given ambiguous and inconsistent results between

107 and 535 million years (Delaloye et al. 1972; ogulu

1975; Moore et al. 1980; JICA 1986; Bergougnan 1987).

More recently, Topuz et al . (2010) reported concor-

dant UPb zircon and ArAr biotite/hornblende ages of

324 and 320 million years, respectively, for granite samples

from the Gmshane pluton. Almost concurrently, Ar

Ar biotite/hornblende/K-feldspar ages between 322 and

306 million years have been obtained for the Kse pluton

(Dokuz 2011).

Prior to this study, knowledge about the emplacement

age of the Kayadibi and Derinoba granites was insufficient

for the reconstruction of their geological history. From

contact relationships and stratigraphic criteria, an Upper

Cretaceous age has been conjectured (Gven 1993). The

new LAICPMS UPb zircon ages of these granites, how-

ever, range from 303.8 1.5 million years (MSWD =

0.12) to 317.2 3.5 million years (MSWD = 1.7).

These ages are more or less coeval with the emplacement

age of the Gmshane and Kse plutons (Topuz et al.

2010; Dokuz 2011). Hence, the Derinoba and Kayadibi

granites are interpreted as members of a larger coher-

ent pluton, referred to here as the eastern Pontide pluton.

Remnants of this pluton either extend below the cover ofthe volcanic and volcaniclastic rocks or are now partly

eroded.

Petrogenesis of the Derinoba and Kayadibi granites

Major and trace element compositional variations in the

Derinoba and Kayadibi granites suggest that fractionation

played a major role during the crystallization of the granitic

magmas (Figure 11). Fractionation of feldspar would also


14/26


2.8

3.0

3.2

3.4

3.6

3.8

4.0

Na2

O(wt.%)

(C)

73 74 75 76 770.5

1.0

1.5

ASI

I-tipi

S-tipiPeralumin

Metalumin

(B)

72 74 76 78

SiO2(wt.%)

0.6

0.8

1.0

1.2

1.4

Ni(ppm)

(P)1.6

73 74 75 76 77

SiO2(wt.%)

20

25

30

35

40

45

Y(ppm)

(Q)

73 74 75 76 77

SiO2(wt.%)

8

12

16

20

Nb(ppm)

(R)

73 74 75 76 77

40

80

120

160

200

Rb(ppm)

(M)

73 74 75 76 770

4

8

12

16

Pb(ppm)

(N)

73 74 75 76 774

8

12

16

20

24

28

Th(ppm)

(O)

73 74 75 76 77

40

80

120

160

200

240

Zr(ppm)

(J)

73 74 75 76 77

400

500

600

700

800

900

Ba(ppm)

(K)

30073 74 75 76 77

20

40

60

80

100

120

140

Sr(ppm)

(L)

73 74 75 76 77

0.8

1.2

1.6

2.0

2.4

2.8

Fe2

O3

T(wt.%)

(G)

73 74 75 76 770.04

0.08

0.12

0.16

0.20

T

iO2

(wt.%)

(H)

73 74 75 76 77

0.02

0.04

0.06

P

2O

5(wt.%)

(I)

73 74 75 76 77

0.0

0.4

0.8

1.2

1.6

CaO(wt.%)

(D)

73 74 75 76 770.0

0.2

0.4

0.6

0.8

MgO(wt.%)

(E)

73 74 75 76 7711.6

12.0

12.4

12.8

13.2

13.6

Al2O

3(wt.%)

(F)

73 74 75 76 77

0

2

4

6

K2

O(wt.%)

Medium-K

High-K

Shoshonitic

Low-K

(A)

68 72 76 80

Figure 5. (AR) Variation diagrams of SiO2(wt.%) versus major oxides (wt.%) and trace elements (ppm) for samples from the Derinobaand Kayadibi granites. (A) K2O versus SiO2diagram with field boundaries between medium-K, high-K, and shoshonitic series accordingto Peccerillo and Taylor (1976). (B) ASI versus SiO2 with field boundaries between I-type and S-type according to Chappell and White(1974) and peraluminous and metaluminous fields of Shand (1947). ASI (aluminium saturation index) = molar Al2O3/(Na2O + K2O +CaO). Same symbols as in Figure 4.


15/26


0.1

1.0

10.0

100.0

1000.0

Sam

ple/primitivemantle

Derinoba granite(A)

Ba U Ta La Pb S r Nd H f Eu Dy YbRb Th Nb K Ce Pr P Zr Sm Ti Y Lu

1

10

100

1000

Sample/chondrite

(F)

Ksepluton

Gmhane pluton

La Ce Pr Nd SmEuGdTb Dy Ho Er TmYb Lu

0.1

1.0

10.0

100.0

1000.0

Sam

ple/primitivemantle

Kayadibi granite(B)

Ba U Ta La Pb S r Nd Hf Eu Dy YbRb Th Nb K Ce Pr P Zr Sm Ti Y Lu

0.1

1.0

10.0

100.0

1000.0

Sample/primitivemantle

Ksepluton

Gmhane pluton(C)

Ba U Ta La Pb S r Nd H f Eu Dy YbRb Th Nb K Ce Pr P Zr Sm Ti Y Lu

1

10

100

1000

Sample/chondrite

(D) Derinoba granite

(La/Yb)cn

= 4.69.7

La Ce Pr Nd SmEuGdTb Dy Ho Er TmYb Lu

La Ce Pr Nd SmEuGd Tb Dy Ho Er TmYb Lu1

10

100

1000

Sample/chondrite

(E) Kayadibi granite

(La/Yb)cn

= 2.75.5

Figure 6. (AC) Primitive mantle-normalized trace element patterns (normalizing values from Sun and McDonough 1989) for samplesfrom the Derinoba and Kayadibi granites. (DF) Chondrite-normalized REE patterns (normalizing values from Taylor and McLennan1985). Symbols as in Figure 4.

FG

OGT

1000100

Zr + Nb + Ce + Y(ppm)

1

10

100

FeOT/MgO

A-tipi

(A)

1

2

3

46

1-Mantle fractionates2-Pre-plate collision3-Post-collision uplift4-Late-orogenic5-Anorogenic

0 500 1000 1500 2000 2500 3000

R1 = 4Si11(Na + K)2(Fe + Ti)

0

500

1000

1500

2000

2500

R2=6Ca+2Mg+Al

7

6-Syn-collision7-Post-collision

5

(B)

Figure 7. (A) FeO/MgO versus (Zr+ Nb + Ce + Y) classification diagram (Whalen et al. 1987) for the Derinoba and Kayadibigranites. (B) R1 versus R2 diagram of Batchelor and Bowden (1985). R1 = 4Si 11(Na + K) 2(Fe + Ti); R2 = 6Ca + 2 Mg + Al.Symbols as in Figure 4.


16/26


Table5.

SrandNdisotopedata

fromtheDerinobaandKayadibigranites.

Sample

Type

Age

(millionyears)

Rb

(ppm)

Sr

(ppm)87Rb/86Sr87Sr/86Sr

2m

(87Sr/86Sr)(I)

Sm(ppm)

Nd

(ppm)147Sm/144Nd143Nd/144Nd2m

(143Nd/144

Nd)(I)

Nd(I)a

TDM

b

Derinoba

T135

Granite

317

109.4

0

59.1

0

5.3

683

0.7

31657

9

0.7

0744

4.8

5

23.1

0

0.1

275

0.5

12158

10

0.5

118

9

6.5

7

1.6

5

M43

Granite

317

109.0

0

45.5

0

6.9

510

0.7

37003

9

0.7

0564

5.6

8

26.8

0

0.1

287

0.5

12181

7

0.5

119

1

6.1

7

1.6

3

T136

Granite

317

108.0

0

48.7

0

6.4

346

0.7

36909

9

0.7

0788

4.4

3

21.6

0

0.1

245

0.5

12158

7

0.5

119

0

6.4

5

1.6

0

T137

Granite

311

111.0

0

41.2

0

7.8

175

0.7

37215

12

0.7

0262

6.1

6

30.1

0

0.1

243

0.5

12179

7

0.5

119

3

6.0

8

1.5

6

T138

Granite

311

114.0

0

39.4

0

8.3

957

0.7

37461

12

0.7

0030

7.7

6

31.3

0

0.1

505

0.5

12182

7

0.5

118

8

7.0

7

2.1

5

Kayadibi

T5

Granite

303

156.2

0

65.2

0

6.9

485

0.7

32976

9

0.7

0301

7.0

9

35.1

0

0.1

226

0.5

12172

8

0.5

119

3

6.2

3

1.5

5

N12

Granite

303

145.6

0

64.9

0

6.5

052

0.7

30215

8

0.7

0217

7.1

6

35.7

0

0.1

218

0.5

12195

9

0.5

119

5

5.7

5

1.5

0

N15

Granite

303

128.3

0

61.1

0

6.0

872

0.7

27663

9

0.7

0142

8.1

2

36.3

0

0.1

358

0.5

12210

8

0.5

119

4

6.0

0

1.7

2

M16

Granite

303

118.5

0

58.8

0

5.8

393

0.7

22586

9

0.6

9741

8.6

4

36.5

0

0.1

437

0.5

12300

9

0.5

120

1

4.5

5

1.7

2

Notes:aNd(I)valuesarecalculatedbasedonpresent-day

147Sm/144Nd=

0.1

967and143Nd/144Nd=

0.5

12638(JacobsenandWa

sserburg1980).

bSingle-stagemodelage(TDM),calc

ulatedwithdepletedmantlepresent-dayparame

ters

143Nd/144Nd=

0.5

13151and147Sm/144Nd=

0.2

19.

Table6.

PbisotopedatafromtheDerinobaandKayadibigranites.

Sample

Type

Age(millionyears)

Pb(ppm)

U(ppm)

Th(p

pm)

206Pb/204Pb

(206Pb/204Pb)(I)

207Pb/204Pb

(207Pb/204Pb)(I)

208Pb/204

Pb

(208Pb/204Pb)(I)

Derinoba

T135

Granite

317

7.3

0

4.0

0

18.90

19.0

9

17.3

1

15.6

7

15.5

8

39.12

36.3

8

T136

Granite

317

12.7

0

2.8

0

14.50

18.7

1

18.0

0

15.6

6

15.6

2

38.86

37.6

7

Kayadibi

T5

Granite

303

11.0

0

6.9

0

24.10

19.2

4

17.2

9

15.6

5

15.5

5

39.09

36.8

8


17/26


(87Sr/86Sr)I

15

10

5

0

5

Nd(I)

Gmhane pluton

Kse pluton

(A)

KayadibiDerinoba

0.693 0.696 0.699 0.702 0.705 0.708 0.711 0.714 SiO2(wt%)

0.6800

0.6900

0.7000

0.7100

0.7200

(87Sr/86Sr)I

(B)

FC

AFC

74 75 76

SiO2(wt.%)

0.5116

0.5118

0.5120

0.5122

(143Nd/144Nd)I

(C)

74 75 76

Nd

0.5118

0.5119

0.5119

0.5120

0.5120

0.5120

(143Nd/144Nd)I

(D)

20 24 28 32 36 40

(206

Pb/204

Pb)I

15.3

15.4

15.5

15.6

15.7

15.8

15.9

16.0

(207Pb/204Pb)I

UC

LC

EMII

EMI

HIMU

NHRL

Geochron (E)

17 18 19 20 21 22

17 18 19 20 21

(206

Pb/204

Pb)I

15.3

15.4

15.5

15.6

15.7

15.8

(207Pb/204Pb)I

Upper crust

Orogen

Mantle

Lower crust

(F)

Figure8. (A) Nd(I)versus (87Sr/86Sr)(I)diagram for theDerinoba and Kayadibigranites.(BD) (

87Sr/86Sr)(I)and (143Nd/144Nd)(I)versus

SiO2and Nd plots, respectively. (E and F) Pb isotope correlation plots of the Derinoba and Kayadibi granites. EMI, enriched mantle type

I (Zindler and Hart 1986); HIMU, high-( = 238U/204Pb, Lustrino and Dallai 2003); EMII, enriched mantle type II (enriched in Sr);LC, lower crust; NHRL, Northern Hemisphere Reference Line (Hart 1984); UC, upper crust. Mantle (MORB), orogen, upper crust (UC),and lower crust (LC) evolution lines are from Zartman and Doe (1981). Symbols as in Figure 4.

result in the depletion of Ba and Sr. Negative Eu anoma-

lies and a decrease in Sr with increasing silica (Figure 5L)

indicate that plagioclase is an important fractionating

phase. The rocks show similar REE patterns, with a general

increase of both light and heavy REEs with increasing

SiO2(Figure 6). The magnitude of the negative Eu anoma-

lies increases with increasing SiO2 contents, suggesting

fractionation of plagioclase for both granites. Fractionation

of FeTi oxide may be responsible for the negative anomaly

in Ti. The negative anomaly in P is most probably the

result of apatite fractionation (Figure 6). Garnet may have

not been involved in magma genesis (Table 4); chondrite-

normalized REE patterns show almost no fractionation

between middle and heavy REE, and Sr/Y ratios are low

(i.e. 1.23.7).

The Derinoba and Kayadibi granites are high-K calc-

alkaline rocks, and their primitive mantle-normalized

spider diagrams are characterized by pronounced neg-

ative Ba, Sr, Ti, and Nb anomalies and enrichment

in Rb, K, and La. These are typical features of syn-

orogenic crustal-derived granitoids. Moderate to high

Rb/Sr ratios (0.55.2) and high K2O (3.24.8 wt.%) and

SiO2(7477 wt.%) contents are consistent with the deriva-

tion from a metasedimentary or felsic micaceous crustal

source (cf. Van de Flierdt et al. 2003; Jung et al. 2009).

Moreover, Nb/Ta ratios vary from 5.7 to 20.5 (average

value = 12.7), Zr/Hf from 24.3 to 51.4 (average = 30.5),

and Th/U from 2.5 to 13.8 (average = 5.40). These

geochemical signatures also suggest the derivation of these

magmas from the partial melting of crustal rocks.

The ASI values indicate strongly peraluminous com-

position, as expected for melts derived by partial melting

of continental crustal rocks. Hence, a derivation from

crustal sources is apparent. The heterogeneity of the initial


18/26


19/26


Table7.

(Continued).

Measuredratios

Correctedages(millionyears)

Spot

207Pb/206Pb

1

20

7Pb/235U

1

206Pb/238U

1

208Pb/

232Th

1

238U/232Th

1

207Pb/206P

b1

207Pb/235U

1

206Pb/238U1

208Pb/232Th1

M16-0

5

0.0

53

0.0

0134

0.3

51

0.0

0893

0.0

48

0.0

0065

0.0

16

0.0

0031

2.1

42

0.0

2

323

34

305

7

303

4

318

6

M16-0

7

0.0

55

0.0

0151

0.3

65

0.0

1006

0.0

48

0.0

0066

0.0

14

0.0

0029

1.4

81

0.0

1

409

37

316

7

303

4

290

6

M16-0

8

0.0

53

0.0

0137

0.3

55

0.0

092

0.0

48

0.0

0065

0.0

16

0.0

0031

1.7

88

0.0

2

337

35

309

7

305

4

312

6

M16-0

9

0.0

53

0.0

0158

0.3

52

0.0

1052

0.0

48

0.0

0067

0.0

15

0.0

0032

1.4

58

0.0

1

315

43

306

8

305

4

307

6

M16-1

0

0.0

55

0.0

0144

0.3

6

0.0

0951

0.0

48

0.0

0065

0.0

15

0.0

0031

1.7

39

0.0

2

392

35

313

7

302

4

310

6

M16-1

1

0.0

54

0.0

0148

0.3

6

0.0

0984

0.0

48

0.0

0066

0.0

14

0.0

0028

1.2

65

0.0

1

369

37

312

7

304

4

279

6

M16-1

2

0.0

56

0.0

0165

0.3

7

0.0

1093

0.0

48

0.0

0067

0.0

16

0.0

0035

2.1

78

0.0

2

320

109

305

12

303

4

303

4

M16-1

4

0.0

53

0.0

0165

0.3

48

0.0

1078

0.0

48

0.0

0067

0.0

16

0.0

0036

1.7

71

0.0

2

322

45

303

8

300

4

325

7

M16-1

5

0.0

52

0.0

0139

0.3

47

0.0

0925

0.0

48

0.0

0066

0.0

16

0.0

0032

1.8

25

0.0

2

293

36

302

7

304

4

313

6

M16-1

6

0.0

57

0.0

0181

0.3

78

0.0

1199

0.0

49

0.0

0069

0.0

15

0.0

0034

1.3

88

0.0

1

473

45

326

9

305

4

305

7

M16-1

7

0.0

53

0.0

0145

0.3

53

0.0

0963

0.0

48

0.0

0066

0.0

16

0.0

0034

2.0

36

0.0

2

330

37

307

7

304

4

328

7

M16-1

8

0.0

53

0.0

0154

0.3

55

0.0

1026

0.0

49

0.0

0067

0.0

16

0.0

0035

1.7

07

0.0

2

327

41

308

8

306

4

322

7

M16-1

9

0.0

53

0.0

0144

0.3

53

0.0

0956

0.0

48

0.0

0066

0.0

12

0.0

0025

1.2

6

0.0

1

329

37

307

7

304

4

243

5

M16-2

0

0.0

53

0.0

0161

0.3

52

0.0

1065

0.0

48

0.0

0067

0.0

15

0.0

0032

1.7

81

0.0

2

331

43

306

8

303

4

295

6

M16-2

1

0.0

54

0.0

0144

0.3

58

0.0

0958

0.0

48

0.0

0066

0.0

15

0.0

003

1.6

53

0.0

2

365

36

311

7

304

4

291

6

M16-2

2

0.0

54

0.0

0192

0.3

58

0.0

1262

0.0

48

0.0

007

0.0

16

0.0

0045

3.6

57

0.0

4

366

53

311

9

304

4

320

9

M16-2

3

0.0

53

0.0

0146

0.3

56

0.0

0966

0.0

48

0.0

0066

0.0

13

0.0

0027

1.5

75

0.0

2

349

37

309

7

304

4

253

5

M16-2

4

0.0

55

0.0

0165

0.3

66

0.0

1089

0.0

48

0.0

0067

0.0

16

0.0

0034

1.6

4

0.0

2

417

42

317

8

303

4

311

7

M16-2

5

0.0

53

0.0

0145

0.3

52

0.0

0962

0.0

48

0.0

0066

0.0

15

0.0

0032

1.3

46

0.0

1

319

38

306

7

304

4

297

6

M16-2

6

0.0

52

0.0

0182

0.3

49

0.0

12

0.0

48

0.0

007

0.0

15

0.0

0034

0.9

63

0.0

1

302

52

304

9

304

4

298

7

M16-2

7

0.0

53

0.0

0166

0.3

53

0.0

1089

0.0

48

0.0

0068

0.0

16

0.0

0038

1.9

22

0.0

2

333

44

307

8

304

4

326

8

M16-2

8

0.0

54

0.0

016

0.3

57

0.0

1055

0.0

48

0.0

0067

0.0

14

0.0

0031

1.3

91

0.0

1

351

42

310

8

305

4

277

6

M16-2

9

0.0

56

0.0

0168

0.3

77

0.0

1115

0.0

49

0.0

0068

0.0

15

0.0

0034

1.8

48

0.0

2

461

41

325

8

306

4

293

7

M16-3

0

0.0

53

0.0

0169

0.3

53

0.0

1113

0.0

48

0.0

0068

0.0

15

0.0

0034

0.9

71

0.0

1

320

46

307

8

305

4

299

7

Notes:Errorsare1.

206Pb/

238Uagevaluesareusedinthetextastheweightedmean.


20/26


290

300

310

320

330

340

0.046

0.048

0.050

0.052

0.054

207Pb/

235U

206Pb

/238U

Data point error ellipses are 68.3% conf

Mean = 317.2 3.5 million years,

95% conf. n= 11, MSWD = 1.7

T135 Derinoba granite (B)

290

294

298

302

306

310

314

318

0.0455

0.0465

0.0475

0.0485

0.0495

0.0505

0.32 0.34 0.36 0.38 0.40 0.42 0.44 0.46

0.30 0.32 0.34 0.36 0.38 0.40 0.42

207Pb/

235U

206Pb/238U


Mean = 303.8 1.5 million years

95% conf. n= 28 MSWD = 0.119

M16 Kayadibi granite (C)

290

300

310

320

330

0.045

0.047

0.049

0.051

0.053

0.30 0.32 0.34 0.36 0.38 0.40 0.42 0.44

207Pb/

235U

206Pb/238U


Mean = 311.1 2.0 million years,

95% conf. n= 23, MSWD = 1.4

T138 Derinoba granite (A)

Figure 9. (AC) Concordia diagrams showing LAICPMS UPb zircon dating results from (A and B) Derinoba granite (samplesT138 and T135) and (C) Kayadibi granite (sample M16).

(A) T138 (B) M16

100 m100 m

Figure 10. (A and B) Cathodoluminescence images of typical zircons from (A) Derinoba granite (sample T138) and (B) Kayadibi granite(sample M16).

Sr isotope values is also consistent with this interpreta-

tion. However, the granites have undergone deformation

and alteration to variable degrees. Therefore, a prudent

assumption is that the measured Rb/Sr and 87Sr/86Sr

ratios have been modified to a certain extent, at least in

some samples. Extremely low (87Sr/86Sr)(I) values (e.g.

0.69740.7003) have been found in samples, showing signs

of aqueous alteration. Therefore, these values do not pro-

vide a significant geological meaning. On the other hand,

Nd isotope ratios are known to be more robust during

alteration and provide less ambiguous constraints on the

origin of these rocks. Initial 143Nd/144Nd isotope values


21/26


Sr

10

100

1000

Rb

Pl

Kf

Bi

Cpx Hb

(A)

10 100 1000 10 100 1000

Sr

10

100

1000

Ba

Pl

Kf

Bi

CpxHb (B)

Figure 11. (A and B) Variation of (A) Rb versus Sr and (B) Ba versus Sr. Fractionation vectors were calculated according to the partitioncoefficients listed in Rollinson (1993). Symbols as in Figure 4.

(0.511880.51201) of the studied granites are homoge-

neous with negative Nd(I) values (4.6 to 7.1), con-

firming the derivation of granitic magma from crustal

sources.

Experimental data on high-K calc-alkaline granitoid

rocks show that such rocks can be produced by melt-ing different crustal sources (e.g. Roberts and Clemens

1993). Furthermore, partial melting yields compositional

differences among magmas produced by melting com-

mon crustal rocks, such as amphibolites, tonalitic gneisses,

metagreywackes, and metapelites under variable melting

conditions (e.g. Patio-Douce 1999). This compositional

variation can be visualized in terms of major oxide ratios

(Figures 12A12D) or molar oxide ratios (Figures 12E

12G). The plots in Figures 12A12F show that partial

melts derived from metapelites and metagreywackes source

rocks have higher molar (Na2O + K2O)/(FeOT + MgO

+ TiO2) and K2O/Na2O ratios as well as lower molar

CaO/(MgO + FeOT) and Na2O, relative to those originated

from the mafic to intermediate source rocks (Figure 12).

Most samples from the Derinoba and Kayadibi granites

plot in the metagreywackes field (Figure 12) and show

high molar (Na2O + K2O)/(FeOT + MgO + TiO2) and

molar K2O/Na2O ratios but relatively low CaO/(MgO +

FeOT). In the Al2O3/TiO2 versus CaO/Na2O diagram

(Figure 12H), the granites show varying CaO/Na2O val-

ues, which indicate the protolith composition of a mixture

of sandstone and argillaceous rocks. These features, asso-

ciated with relatively low Mg-number values (933), sug-

gest melt production from lower crustal metasedimentary

source rocks. A similar origin is suggested for granophyresfrom the Gmshane pluton (Topuzet al. 2010).

Geodynamic implications

Hercynian plutonism in Turkey is confined spatially to the

Pontides, specifically to its eastern portion (Figure 1B).

The subduction polarity and geotectonic evolution of

the eastern Pontide orogenic belt are still controversial.

The various models proposed for the subduction polar-

ity of the eastern Pontides can be grouped into three:

(i) Adamia et al. (1977) and Ustamer and Robertson

(1996) suggested that the eastern Pontides developed by the

northward subduction of the Palaeotethys, which was situ-

ated to the south of the magmatic arc, from the Palaeozoic

until the end of the Eocene; (ii) Sengr and Ylmaz

(1981) proposed that the Palaeotethys was situated to the

north of the Pontides, and hence southward subductionoccurred from the Palaeozoic until the Middle Jurassic,

whereas northward subduction occurred subsequently from

the Upper Cretaceous until the end of the Eocene; (iii)

Dewey et al. (1973), Bektas et al. (1999), and Eyuboglu

et al. (2007) suggested that southward subduction contin-

ued uninterruptedly from the Palaeozoic until the end of

the Eocene.

Researchers are likewise debating whether the eastern

Pontides belong to Gondwana or Eurasia (Laurussia)

(Sengret al. 1980; Sengr and Ylmaz 1981; Robertson

and Dixon 1984; Robinsonet al. 1995; Okay and Sahintrk

1997; Ylmaz et al . 1997; Wehrmann et al . 2010).

The oceanic domain between Gondwana and Eurasia

(Laurussia) is known as the Palaeotethys. The location

of the eastern Pontides during the late Palaeozoic era

is contentious. Some authors have suggested that the

eastern Pontides formed part of the active nor

Documents

Geochronological Evidence and Tectonic s