PROTHOLITHIC AGE AND GEOCHEMISTRY OF MAGMATIC ROCKS FROM THE SERBO-MACEDONIAN MASSIF (SOUTH , SOUTHWEST BULGARIA AND MACEDONIA) M. Antić¹, I. Peytcheva², A. von Quadt³, A. Kounov¹, B. Trivić⁴, T. Serafimovski⁵, G. Tasev⁵ and I. Gerdjikov⁶ ¹Geologisch-Paläontologisches Institut, Universität Basel, 4056 Basel, Switzerland, ²Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria, ³Institute of Geochemistry and Petrology, ETH-Zürich, 8092 Zürich, Switzerland, ⁴Faculty of Mining and Geology, University of , 11000 Belgrade, Serbia, ⁵Faculty of Natural and Technical Sciences, University "Goce Delčev" - Štip, 2000 Štip, Republic of Macedonia, ⁶Faculty of Geology and Geography, St. Kl. Ohridski University of Sofia, 1504 Sofia, Bulgaria

Serbo-Macedonian massive (SMM) is a N-S stretched zone, situated Results of the fission-track analysis on zircon and apatite grains from the magmatic rocks of the LA-ICP-MS U-Pb analysis of igneous rocks from the SMM and surrounding units ( 22°E Lower complex, unit, Crnook dome and Late magmatic bodies is presented in figure 2.1. in the central part of the Balkan Peninsula. It outcrops from the yielded magmatic ages (red) grouped in four clusters, and various inherited ages Era Period Epoch Modelling of the thermal evolution of the samples, using the HeFTy software, yielded three dif-

Pannonian basin in the north, to the Aegean sea in the south. SMM (orange) as old as Mesoarchean. The oldest, Cadomian event is recorded in both ferent major thermal histories. Please note that the annealing model is not sufficiently sensitive parts of the SMM, Veles series as well as Crnook dome. Ordovician igneous activ- ( 43°N

.! 43°N is bounded by the west-vergent Eastern Vardar zone (remnant of below 60°C. Figure 2.2 depicts the effects of late Eocene cooling following the 37-31 Ma pulse of

43°N43°N ity continued only in the Lower complex and the Veles unit. There are two occur- SM331 Lece 30 SM207-1

( Mesozoic Tethys) in the west, and is thrusted over the east-vergent magmatic activity. This event affected most of the observed samples from the Vlasina unit. rences of late Permo-Triassic magmatism in western Lower complex, and in

33±0.5 33±2 SM216-1 Oligocene

( Geticum units in the east. The SMM is divided into the Lower com- Samples from the Crnook dome revealed the fast cooling in early Eocene related to tectonic Crnook dome. Late granite was intruded in late Eocene, followed by the

Južna Morava 35±1.5 50°N C 30°E unroofing of the Crnook-Osogovo-Lisets core complex (Kounov, 2002), followed by the slow volcanic and hydrothermal activity. 36±1 36±3 ( a plex and the Vlasina unit (upper unit) (Dimitrijević, 1959), both rep- Cenozoic

r Paleogene 18°E pa th cooling (Figure 2.3). Samples from the Vlajna and Kukavica granite of the Lower complex show ia

n resenting volcano-sedimentary complexes, metamorphosed to am- 40

( s relatively fast cooling in the middle late Cretaceous (Figure 2.4). In the late Eocene reheating ( Pannonian phibolite and green schist facies respectively. Contact between Eocene Tran event is observed probably related to the magmatic during that period. Era Period basin .! 0.010 50 A change Ð these two units was interpreted as a brittle Vrvi Kobila westward 150 in scale B Lower complex ages 0 0.009 160 Dark gray = concordance 95-105% 160±4 thrust, outcropping southeast of Leskovac, Serbia (Vukanović et al. 0.60 Light gray = concordance <95% & >105% Vlajna AFT age [Ma] 0.008 40 ( Miocene basin Age group: 200-950 Ma 560±5 Moesia Black Model: 34.9 170

A 0.55 0.007 173±6 Sea 1965). Apart from scarcely documented ‘Pb-Pb zircon ages’ for Measured: 35.1±5.8 F S VELES

D E 20 i R r n GOF: 0.96 180 e B 0.006 30

BALKAN 0.50 q y ( a O t

r u 452±9 i

i l i

83±9 94±5 e d - Vlajna and plutons (450Ma and 347Ma respectively; Ð M Jurassic # b

* n e 0.005 s 190 a A Srednogorie 0.45 MTL [µm] c b 192±7 C y o

E Model: 14.78±0.67 r ( D Dimitrijević, 1997), paleontological findings represent the only P 0.004 20 567±28 *# O 40 200 N 0.40 Measured: 14.51±1.05 I ]

# C

* 488±8 A RHODOPE Vardar

Pelagonia N GOF: 0.98 0.003

( [ ° y *# Vlasinsko j. ( e chronological data related to the age of these metamorphic do- 210 Mesozoic

r 0.35 H c

u

n 0.002 10

t

( ( ( 74±6 e 40°N e a

l u 73±5 83±6 l r 220 q

e e 516±9 ( 60 0.30

mains. Sericite-chlorite schists northeast of were dated e 0.001 n p

i r 225±7 VLASINA F 40°N d m e e STRUMA ( Aegean 230 s T 0.25 0.000 0 2 3 4 5 6 7 8 9

0 0 0 0 0 0 0 0 ( to be of Ripheo-Cambrian age by sphaeromorph acritarchs ( 39±4 79±4 ( Sea 0 0 0 0 0 0 0 0

240 Triassic es 80 0.20 Age [Ma] rid (Rakićević et al. 1969). Palinomorphs found in ‘flysch-like’ sedi- au

250 BASEMENT Božica D T Apatite PAZ 0.15 253±13 C Ð *# Surdulica ments of the northeasternmost thrust of Vlasina unit yielded Devo- 260 *# ( 0.10

( ( 100

( ( nian to lowest Carboniferous age (Pantić, 1960 and 1963). The con- 270 *# 0.05 .! 546±7 ( ( Mediterranean Ð 33±0.5 #* 0.00 280 281±7 18°E Sea 30°E troversial Veles series (Vukanović et al. 1977) with differing lithol- 282±8 0 2 4 6 8 10 12 14 16 18 20 ( 36±1 35±3Ð 120 Length [µm] 281±7 ogy and deformational style (Dimitrijević, 1997) is situated in the 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 290 Permian # Time [Ma] * 299±9 300 ( Bujanovac # southwest of the research area, between the Lower complex and Figure 2.2. Late Eocene magmatic cooling. Left: Time-Temperature path; black line represents the best fit model. Right: Track length histogram; green line represents the best fit model. COMPLEX LOWER 42±4 41±4 310 .! 0 313±10 Ð the Eastern Vardar unit. In the eastern part of the SMM, Crnook Miocene basin ( 36±3 23°E 20 320 253±13 F AFT age [Ma] 324±7 dome (part of Crnook-Osogovo-Lisets dome that represents Struma 40 0.35 Model: 39.3 330

60 Measured: 41.6±6.8 *# Ð *# basement) is exhumed during the Cenozoic extension along low GOF: 0.51 340

E 33±2 80 0.30

Apatite PAZ 350 ( Ð angle detachments (Kounov, 2002). Our research is poised to reveal MTL [µm] Carboniferous 100 Model: 14.14±1.05 ]

C 360 SM199-1 Bujanovac Granite SM199-1 Bujanovac

0.25 Measured: 13.95±1.18 MAGMATICS CENOZOIC

[ ° 120 the major magmatic events as well as the deformational history of ( *# e GOF: 0.79 r y u 370

t 140 515±4 c

*# a n r

443±6 e

the area. Apart from the field observations, we are relying on the e 0.20

u 378±5

Legend p Ð 160

q 380

Kjustendil granite SM216-1 Surdulica e m r e F 78±6 T 180 .! low temperature geochronology methods (apatite and zircon fission 390 Ð ( Ð 0.15 ( ( ( 200 Detachments track and Ar/Ar dating) together with U-Pb zircon dating and geo- 400 220 Devonian chemical analyses. 0.10 410 amphibolite SM173-1 Vinica ( Thrusts 240 Zircon 420 Ð 260 422±6 424±14 Osogovo FT age 0.05

280 430 gneiss SM315 Preševo

Paleozoic SM250-1 Golemo Selo amphibolite SM250-1 Golemo Uncertain faults Ð 110 300 440 0.00 Silurian 443±6 Struma 0 2 4 6 8 10 12 14 16 18 20 445±12 ( 60 58 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Length [µm]

Strike-slip faults 450 pl. gneiss SM184-1 Maleševska 452±9 Ð

Time [Ma] rhyolite SM331 Stajovce 100 aplite SM173-3 Vinica Ð Ð Figure 2.3. Early Eocene extension in the area of Crnook-Osogovo-Lisets dome. Left: Time-Temperature path; black line represents the best fit model. Right: Track length histogram; green line 457±11 Lower complex 460

represents the best fit model. Ð 464±6 465±6 0 Unresolved kinematics 470 469±5 469±6 90 Cretaceous granite SM01 Kukavica

( 20

AFT age [Ma] 480 .! Ð basin

40 0.45 Model: 69.4 Ordovician Ð 487±6 488±8 *# 80 60 Measured: 72.8±10.9 490 490±4 489±5 Granitic samples GOF: 0.53 493±10

Apatite 0.40 SM195-1 Štip granite 496±14 Kratovo-zletovo 80 498±32 granite SM272-1 Božica 500 ] 100 PAZ MTL [µm] gneiss Pčinjski SM202-1 Prohor *# a 70 SampledSkopje gneisses 0.35 Model: 13.39±1.01 510 M 120 512±8 513±15 [ 540±7 ] Measured: 13.10±0.98 42°N 516±17 516±12 516±4 516±9 42°N C [ ° .! e GOF: 0.87 140 0.30 520 y 42°N e *# g r *# c Maffic samples 525±6 granite SM140-1 Delčevo

42°N u a 60 n

t

160 e

a u SM250-2 Golemo Selo gneiss SM352 Lisina gabbro T

r 530 ( q

e 0.25 F Cambrian e p 180 r

Vlasina F m 540±7 *# Sampled Cenozoic magmatics e 540 50 T 200 544±27 0.20 546±7 SM02 Vlajna granite 548±6 220 550 549±15 549±16

422±6 240 0.15 560±5 Zircon U-Pb age Delčevo 40 560 560±18 560±5 260 Zircon 567±28 *# 0.10 570 Young 280 573±5 *# 30 FT age Zircon fission track age magmatics 300 0.05 580

79±4 320 586±11

Struma basement 590 590±8 0.00 594±12

469±6 (

340 0 2 4 6 8 10 12 14 16 18 20 ( 20 Length [µm] 600 603±18 42±4 Apatite fission track age 200 400 600 800 1000 1200 1400 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 605±9

Time [Ma] Ediacaran 610 611±14 Altitude [m] Figure 2.4. Middle-late Cretaceous cooling event and mild late Eocene reheating. Left: Time-Temperature path; black line represents the best fit model. Right: Track length histogram; green line Figure 2.1 Fission track age versus sample altitude plot represents the best fit model. 620 Štip 625±13 .! 630

Neogene to Quaternary sediments Banja dacite SM207-1 Vranjska *# Four samples of Cenozoic magmatics from 22°E 640 642±24 512±8 SMM are plotted on Hf-Rb-Ta system ternary Paleogene sediments 650 YOUNG MAGMATIC 554±22 W E classification plot (Harris et al. 1986) and Rb/30 Ta-Yb binary classification plot (Pearce et al. 660 0

Upper Cretaceous sediments 0 *#465±6 Surdulica granite 1 1984) respectively. Surdulica granite and the 670 ( dacite and Stajovce rhyolite 680 ( Ljubata trachyandesite 685±14 Cenozoic volcano-sedimentary rocks are intruded in the Vlasina unit. Their U-Pb 690 695±17 Vranjska banja dacite zircon ages can be found in the figure to the 700

0 WPG

( 1 Cenozoic plutons ( Stajovce rhyolite right. Ljubata trachyandesite was sampled at Vardar 710 Syn-ColG Syn-ColG the Crnook dome (Struma basement). All Mesozoic plutons volcanic samples are plotting in the volcanic 720 Ta arc area with collisional affinity, which is inter- 730 Ogražden Late Permian plutons 1 ( ( VAG preted as a result of contamination with host 740

rock material (of the same chemical signa- Neoproterozoic Strumica Late & Post-ColG 750 Early Paleozoic plutons “Veles series” ture). Surdulica pluton shows collisional gran- ( .! 760 762±24 VAG ORG ite signature, as expected given the current Cryogenian 1

. 770 Proterozoic plutons Eastern Vardar zone .! WPG 0 tectonic models for the Paleogene (eg. ( Cvetković et al. 2004). 780 Vlasina unit (upper complex) Geticum/Struma/Srednja gora 0 10 20 30 40 50 Hf Ta*3 0.1 1 Yb 10 100 790 SMM 800 802±22 Crnook-Osogovo-Lisets dome ( Km Lower complex } 810

(Struma basement) Ð Six samples of mafic rocks have been plotted on the tertiary diagram of the Ð 820 823±20 22°E 23°E MAFICHf/3 ROCKS Th-Hf-Ta-Zr-Nb system (Wood 1980). Where available, U-Pb zircon ages are Q-monzonite SM236-1 830 WSW ENE given in brackets. Gabbro from the Crnook dome (Struma basement) and 3000m 3000m Ordovican amphibolites of the Lower Complex exhibit slightly depleted 840 2000 2000 continental arc signature. The mafics from the Vlasina unit are showing 850 851±24 1000 ? 1000 860 A 0 0 B within plate (Cadomian gabbro) to enriched-MORB affinities (possibly much -1000 Vlajna Tran -1000 younger sub-volcanics). 870 N-MORB 673±21 -2000 -2000 IAT 880 882±28

890 NE SW Mitrašinci trachy-basalt N Tonian S WNW ESE E-MORB, 900 NNE SSW Dobro Polje diabase Vlasina WPT Thus, different sources and/or 910 Lisine gabbro (Cadomian) emplacement scenarios are A change in scale Ljubata gabbro expected for the Vlasina unit Struma basement 1077±29 WPA and the neighboring domains. CAB Vinice amphibolite (Ordovician) Stenian Lower complex 1200 Golemo Selo amphibolite (Ordovician) 1300 Zircon grains show predominantly magmatic zoning (below Ectasian SM315 1380±32 middle) and subordinately patchy zoning in cores (below left) Th Ta 1400 1500 and in grains separated from gabbroic samples (below right). Caly-

mmian 1566±34 Mesoproterozoic 1600 1618±20 Figure above shows weighted average values of results with

1700 concordance between 95-105% (except volcanics and aplites) rian Stathe- PRE-MESOZOIC GRANITES 1800 with 2σ errors. Inset depicts relationship between concordant Rb/30 Eleven Cadomian and Ordovician samples are

0 1882±42 0 1900 and discordant grains from Lower complex in 200-950 Ma age 1 plotted on classification diagrams for granitic SM184-1 SM199-1

rocks (Harris et al. 1986 and Pearce et al. 1984 2000 Orosirian group. respectively). All samples are emplaced in 2064±45 W E 2100 3000m 3000m volcanic arc setting with Štip granite showing 2000 2000 2200 0 Rhyacian

1 collisional affinity. 1000 ? 1000 WPG 2300 2331±46 0 0 D 2350±51 C Paleoproterozoic Surdulica Božica Cadomian Ordovician 2400 -1000 Bujanovac -1000 Syn-ColG Syn-ColG -2000 -2000 Ta Vlajna granite Kukavica granite 2500 Siderian Delčevo granite Maleševska pl. gneiss Lower

1 2600 Prohor Pčinjski gneiss Vinica aplite

VAG Neo WSW ENE complex 2700 3000m 3000m Golemo selo gneiss Vinica gneiss archaean 2000 2000 Late & Post-ColG 2800

1000 1000 Štip granite Preševo gneiss 2900 1 ORG . VAG Veles SM01 SM250-2 E 0 0 F 0 WPG 3000 -1000 Bujanovac -1000 3049±66 3047±59 Božica granite Meso 33±1 -2000 -2000 Vlasina 3100 0.1 1 10 100 archean 3049±66 556±14 Ta Ta*3 Yb 3200