Structural and Fluid Evolution of the Efemçukuru Epithermal Au-deposit, western Turkey Kaleb Boucher , Matías Sánchez , Tim Baker , Aleksandar Mišković , Craig J.R. Hart 1
2
3
1
Acknowledgements
1
(1) Mineral Deposit Research Unit – EOAS; The University of British Columbia, Vancouver, BC, Canada (2) Fault Rocks Inc., Vancouver, BC, Canada (2) Eldorado Gold Corporation, Vancouver, BC, Canada
0
75 0 70 0
4239500
75
h
4239000 4238500
h
h
h
45
h
75
0
550
0
95
0
0
h
h
(Figure 3)
35
h
55
h
17
hh
h
h
21
h 39
A’
Bornova Flysch Zone
Cumaovası Volcanic Rocks
Other Volcanic Rocks
Limestone/Marl
Marble
Spilite
Serpentinite
Tuffs and pyroclastics (Yuntdağ) and trachyite to basalts (Karaburun)
Miocene Sediments
km
Syncline
N
A 1000 NW
Vertical Scale 5:1
Cross-Section A-A’ across the Seferihisar Horst
Efemçukuru Hornfelsed Kestanebeleni Rhyolite flysch Dikes Vein
30
Flysch Bedding (S0)
Inferred/ Probable Fault
Bedding (dip)
Measured Fault
0
A’
Poles to planes (dip-direction)
n = 811
Miocene Sediments
Rose Diagram (dip-direction)
1000
90
270
180
n = 811
500
Cumaovası Volcanics
Miocene Sediments 0m
0m 0 km
10
20
30
325
(041/59°)
n = 44
(332/53°)
n = 41
(043/66°)
n = 79
Individual fault segments physically and mechanically link as the fault systems evolved. The more NNW-trending veins may be linkage zones between the NW-structures that allowed for the localized hydrothermal fluid flow (10).
600
315
75
0
305 295
275 265
µ 800
285
Alluvium
SE
Bornova Flysch
Schist-grade flysch
500
Granodiorite
Limestone
Reactivated Strike-Slip Fault
Rhyolite Dikes
Early Triassic granodiorites and Quaternary Alluvium
Structures Normal and Oblique Slip Fault
Set 2 Faults
Other Rocks/Formations
Thickly-bedded red conglomerates, sandy conglomerates, and limestone
10
Set 1 Faults
Karaburun
Yuntdağ
Azimuth Direction of Lineament 345 (Strike) 335
0
Schist
< 2.00 g/t Au
70
Phyllite
Conglomerates
Pyroclastics
Rhyolite
2.00 - 7.50 g/t Au
0
Tahtalı Dam
Rhyolitic pyroclastic flows and tuffs and overlying dome-forming rhyolite flows and dikes
Olistoliths of altered basalt (spilite), serpentinites, and limestones in a matrix of mudstone, shales, sandy mudstones, and marl metamorphosed to phyllitegrade, and locally to schist-grade.
Rhyolite dikes and epithermal veins follow Set 1, though orientation varies widely (4). The highest gold grades are found in the most NW- and NNW-trending, steeply dipping structures (5). These areas are dominated by veins of Stage IV type veins (6d).
On the deposit-scale, the flysch comprises distinct zones comprising phyllite and schist (3). An area of calc-silicate (epidote-chlorite-actinolite-quartz-pyrite) alteration pre-dates mineralization.
-4
-6
-12
12
14
0
18
20
0.2
0.1 0.2
-6
26
28
30
250°
-7
Fluid 2 200°
Fluid 3
50°
100°
Magmatic Fluids
Degassing
Fossil Meteoric Fluids
(Zheng and Hoefs, 1993; Faure and Mensing, 2005; e Silva et al., 2013)
(Zedef et al. 2000; Lüdecke et al. 2013)
-9
-13
-13 300°
250°
5
10
Fluid 2
Fluid 3
15
20
δ OSMOW of Carbonate (‰) 18
Trend 2
Stage IV Vein Stage V Vein
250°
0
Stage II/III Vein
Fluid 1
50°(40%) degassing Only abundant of a “magmatic”, 25 H2CO3-rich fluid 30 (Fluid 1) may explain carbonate samples with enriched δ18O and depleted δ13C.
Degassing and Cooling
Stage VI Vein Deposit-Scale Flysch
-15
Regional-Scale Flysch
-10
-5
0
5 δ OSMOW of Fluid (‰)
10
15
0 700
650
65
0
75
0
497500
498000
498500
499000
500 Meters 499500
1000
Kestanebeleni Longsection
NW
South Ore Shoot Middle Ore Shoot
North Ore Shoot
600 m
Kokarpınar Longsection
SE
NW
600 m
500 m
400 m
IsotopeTrend Trend Isotope
Trend Trend 1 1 Trend Trend 2 2 Trend 1200 Trend 1and and m2 2
Trend 1 Trend 2 Trend300 1 and m 2
0.4
-10
≥0
0.4
18
20
22
24
26
28
30
≥5
200 m
≥ 10
100 m 100 m
≥ 25
≥ 50
200 m
Total goldgrade grade per meter of vein (g Au/m) Total gold per meter of vein (g Au/m)
Total gold grade per meter of vein (g Au/m) Cooling
300 m
≥ 00
100 m
≥ 10 ≥ 25 ≥ 25 ≥ 50≥ 50 ≥ 90≥ 90 ≥≥55 ≥ 10
≥ 90
32
δ OSMOW of Calcite (‰) 18
rupture termination at fault intersection
Summary & Conclusions
localized fluid flow
(10)
All vein stages (I-VI) likely originated from mixing of meteoric fluids with host flysch rocks. A minor magmatic component may have contributed fluids and metals. Fluid mixing was the common, background process for vein carbonate precipitation. Boiling was an important mechanism for high grade gold mineralization.
Figure 4: Analysis of Dip Direction and Dip measurements of surface vein trends on the deposit. Stereonets are in Equal Area Projection, Lower Hemisphere, made by Figure 5: Lineament map, outlining directions of Set 1 structures (veins, faults, and dikes) and gold grades from surface. Colors of lineament correspond to azimuth direction. Grades supplied by Eldorado Gold Corp.
aftershock zone
500000
[1, 9]. Averages based on Mean Pole Vector, displayed as square, and the corresponding great circle (dark grey line).
(Kokarpınar Vein) Figure 7: Schematic diagram of fluid flow in linked fault segments. Flow is triggered after rupture and occurs in both the main structure (blue) and aftershock structures (red). The main structure will become sealed due to mineral deposition, decreasing fluid flux. Fluid flow in the linked structures in the aftershock zone, however are continuously rejuvenated allowing for a localization, and longer lived fluid flow. Modified from [14]. References: See supplemental sheet
20
18
(9b)
(9a)
Isotope 400 mTrend
16
-7
-11
100°
32
0.2
14
-5
Stage I Vein
-11
-15
-3
50°
-9
Trend 1
Fluid Mixing
-1
50°
500 m
0.3
-12 12
-5
700 m
0.3
-8
HCO3- Fluid Model
Fluid 1
300°
SE 24
300
-3
0.4
0.4
H2CO3 Fluid Model
δ 13CPDB of Fluid (‰)
δ 13CPDB of Carbonate (‰) 50° C 0.2
300°
300
Tethyan Marine Carbonate & Sediments
Depleted Flysch
(Föllmi et al., 1994; Jarvis et al., 2000; Faure and Mensing, 2005)
1
Regional-Scale Flysch
-1
0.3
22
Cooling
3
Stage V Vein
300°
HCO3 as the dominant carbon species
-2 0.05
-4
16
Process Effects on 13C & 18O
Stage IV Vein
1
0.3
Cooling
5
Stage III Vein
Deposit-Scale Flysch
-8
250° C
Trend 2 is best explained by abundant degassing (>40%) of mixed fluids with a minor magmatic component (8).
0.1
δ18OSMOW +7.0 ‰ +2.0 ‰ -2.0 ‰
Epithermal veins and rhyolite dikes follow a NW-trending set of structures. Steepest and increasingly NNW-trending vein segments contain the highest gold grades, which may represent “linkage zones”, localizing hydrothermal fluid flow.
7.50 - 25.0 g/t Au
4238000
h
29
H2CO3 as the dominant carbon species
δ13CPDB -2.0 ‰ -4.0 ‰ -6.0 ‰
Fluid Corrected 13C & 18O Sources
diffuse fluid flow
0 85
h
h
35
4237500
h
47
80
Aegean Sea
Figure 2: Geologic map of the Seferihisar Horst with cross section A-A’. Fault structures are modified from M. Sánchez, (pers. commun., 2014). Regional geology base map modifed from [8]. ASTER GDEM image are a product of METI and NASA. Stereonets created by [1,9]
Fa Orh ul an t Z lı on e
h
68
h
h
0
> 50.0 g/t Au 25.0 - 50.0 g/t Au
40
0
(8b)
Cooling Model, 40% Degassing (Rayleigh)
Fluid (initial condit.) 5 Fluid 1 (Magmatic) Fluid 2 (Mixed) 3 Fluid 2 (Meteoric)
(7)
-2
Trend 1 data may be explained by mixing of meteoric fluids and flysch host rocks.
(8a)
Figure 7: Effects of degassing and cooling on carbonate isotopes precipitated from hydrothermal fluids from 300° to 50° C. Modified from [23] Figure 8a: Rayleigh model based on equations from [23] and fractionation factors from [2,7,15] of abundant degassing and cooling fluids. 8b: Fluid corrected isotope values of all vein stages exhibits two data trends. Figure 9a: Comparison of two trends in both Kestanebeleni and (9b) Kokarpinar.
Carbonate precipitated from cooling of hydrothermal fluids causes an δ18O enrichment , and degassing (boiling) causes a depletion in δ13C depending on temperature and carbon species (7).
6
Metal Grade
70
Structural Measurements indicate two main fault trends: a subordinate NW-trending normal fault trend (Set 1) and a dominant NE-trending normal to strike-slip (reactivated) trend (Set 2).
53
65
0
80
0
66
65
700
75
h
31
45
Two main sets of structures occur within the deposit: Set 1: NW-trending normal to oblique normal faults Set 2: NE-trending oblique-normal to strike-slip faults
Basement rocks hosting the Efemçukuru deposit comprise the Bornova Flysch, exposed in the NE-trending Seferihisar Horst (2). Miocene sedimentary and volcanic rocks (Cumaovası volcanics) overlie the flysch to the SE and NW.
Efemçukuru
37
n = 19
Figure 1: Simplified geologic map of western Turkey. Modified from [21,22]. Deposit and geology information from [16,18,22]. LS = Low Sulfidation Epithermal, IS = Intermediate Sulfidation Epithermal, Porph = Porphyry.
0
4238500
h h
h h h h h
h
18
Trend 2 data is more abundant in Kestanebeleni, than Kokarpınar, and may indicate boiling is important for consistently high gold grades (9).
90
h
h
h
h h
Sef e Fau rihisa r lt Z one (136/64°)
h
18
45
5 cm
5 cm
Degassing
60
h
n = 41
58
comb qtz
300° C
650 0
22
comb qtz
50° C
80
900
36
64
gal-py-cpy band
mosaic qtz-sph
100° C
Dike & Vein Lineament Analysis with Soil and Rock Au Assays
0
0 60
95
h
05
41
(320/64°)
50
cal vein
100° C
500
500000
499500
950
850
(5)
37 48
(6f)
clay + rds
T < 200° C
499000
850
h
h
wall rock
150° C
498500
498000
497500
650
Figure 3: Geologic map of the Efemçukuru deposit, with cross section B-B’. Cross section complete with geology from DDH listed.
h 46
32
(6e)
rdn/rds-py
Degassing
75
h
h
26
32
(6d)
150° C
0
33
41
Stage V
200° C
65
65
34
Stage IV
1 mm
5 cm
5 cm
200° C
700
?
n = 25
77
qtz-rdn-rds-ax
250° C
4238000
h h h
h
hh
h
hh
032/82° 065/73°
250
Set 1 Faults (conjugate)
wall rock
5 cm
T > 200° C
0
0
Set 2 Faults
qtz-rdn
act
δ 13CPDB of Calcite (‰)
?
act qtz-ax
The spread of data show two main trends: positively sloping Trend 1 and negatively sloping Trend 2.
75
KV-416
?
bladed qtz-rds
act
-10
500
epi
Figure 6: Representative samples and photomicrographs of the main vein stages. 6a: actinolite-epidote-quartz-chlorite cut by later quartz-axinite; 6b: phyllite wall rock cut/brecciated by quartz, and rebrecciated by rhodochrosite.; 6c: boiling textures as bladed rhodochrosite-quartz vein, cut by later crustiform quartz-rhodonite veins. 6d: band of sulfides at base of cockade, with various quartz types grown from brecciated wallrock clast, and Stage VI late calcite vein; 6e: Comb-quartz-sulfide aggregate band between carbonate vein and coarse-grained massive sulfides. 6f: lump of sulfides in Stage IV vein exhibiting Au-bearing pyrite, mostly in fractures, but also as free Au.
(6c)
(6b)
qtz breccia
300° C
h
h h h hhh h
h
0
0 95 70 0
h hh h
60
039/43° KV-129 040/45°
95
80
0
h
h
60
47
hh
060/80° KV-143 KV-128 KV-123
045/75°
qtz
Degassing
040/85°
010/85°
035/65°
Stage III
Stage II
(6a)
δ 13CPDB of Calcite (‰)
750
Kokarpınar
600
600
Göktepe
800
70
Dedebağ
Stage I
Carbon (δ C) and oxygen (δ O) isotope data were obtained for all vein stages. 13
0
497000
NE
SW
1000
500000
4239000
Meters above sea level
500
496500
499500
KP-1
DB-1
Meters
B’
Kestanebeleni
0
80
Kokarpınar Vein
4239500
4237500
h
h
1000
Dedebağ Vein
0
1000
Meters 499000
µ
4237500
hh
h 75
498500
498000
497500
More Pb-Zn massive sulfides, and fewer boiling textures are in Stages IV and V veins, prevalent at depth and in the Northern Ore Shoot.
0
0
15
70
500
0
497000
µ 0
0
[email protected]
5 Hydrothermal Fluid Evolution
Kestanebeleni Vein 75
65
038/78°
KB-1
0
700
Boiling textures with fewer sulfides, are found in Stages II, III, and IV and are abundant in the SOS and MOS.
0
75
0
(226/59°)
h
70
n = 12
Kokarpınar Vein
h
B
A (068/48°)
h
h
µ
hhh
600
650
0
KP-2
hh h
Dedebağ Vein
B
26 10 5
*Averages in Dip Direction/Dip
KB-2
800
S0 bedding
DB-1
KP-3
65
60
Pebble Dike
058/68° 022/55° 024/61° 90
70
Vein
Kestanebeleni Vein
KB-1 KB-2 KB-3
Six major vein stages are identified based on mineralogy, textures, and cross cutting relationships. Early calc-silicate veins (Stage I) occur in the Southern Ore Shoot (SOS) and the Middle Ore Shoot (MOS) of Kestanebeleni
13 9 8 20 31
75
73
h
002/38° 042/38° 004/59° 036/75° 065/66°
n
0
Phraetomagmatic Breccia
h
48
KP-1 KP-2 KP-3 KP-4 KP-5
0
85
h
Stockwork Veins
Izmir Bay
hh
63
h
60
52
Average
85
75
h
Dikes/Epithermal Veins
496500
0 65
0
80
0
Geology of the Seferihisar Horst Region
hh h h
h
70
(2)
80 75 0
(qtz-chl-epi-act-py)
Interpreted fault
60
700
h
Calc-Silicate Alteration
Crustal extension induced by slab rollback of the Hellenic Slab in western Anatolia began in the late Oligocene (ca. 25 Ma) with NNE-directed extension, exposing the Menderes Massif and the Cycladic Core Complex (1). [16, 21] NE-SW trending volcano-sedimentary basins across western Turkey, are cut by later E-W trending grabens, and Pliocene strike-slip faults [21]. Set 1 Faults (conjugate)
h h
h
Marble
Strike-Slip/Oblique fault
Set 1 Faults
h
Mineral Deposit Research Unit University of British Columbia Vancouver, BC, Canada V6T 1Z4
0
0
Schist
Normal fault (dip)
650
0
45
MSc Student
75
Spilite
65
KP-4
h
Phyllite
Determine the fluid source(s) and mechanisms of metal deposition
h
21
h
Bornova Flysch
Identify the roles of local and regional structures on localization of ore mineralization
Zone
KB-3 h
34
h
82
32
Rhyolite Dikes
Western Turkey comprises Eurasian-derived Sakarya Zone and the Gondwana-derived Antolide-Tauride block sutured together by subduction of the Northern Neotethys [16].
h 850
h
Legend
75
Low- and Intermediate-sulfidation epithermal deposits are structurally controlled hydrothermal mineral deposits [3, 10, 12, 19]. Mineralized veins are commonly hosted in normal faults formed in extensional settings [12, 14]. Fluids are dominantly meteoric but metals are derived from magmatic fluids [10]. Some epithermal systems have an unclear link to magmatism. We examine the structural controls and fluid evolution of the Efemçukuru deposit through the following objectives.
h h h h
h hh h h h h
Direction of Hangingwall displacement
900
600
90
h
39° E 38° E
50 km
850
h
Major Suture
700
Efemçukuru Epithermal Vein Structural Analysis
850
Major thrust Fault
44
60
850
Detachment Fault
33
h
1. Efemçukuru (LS/IS, Au) 2. Kalecık (LS, Hg) 3. Arapdağ (IS, Au-Ag-Pb-Sb) 4. Ovacık (LS, Au-Ag) 5. Küçükdere (LS, Au) 6. Balya (IS, Au-Ag-Pb-Zn) 7. Sındırgı (LS, Au-Ag) 8. Kişladağ (Porph, Au)
Normal/oblique Fault
Gökova Gulf
)
0
h
h
hhh hh
Aegean Sea
65
4238500
Undifferentiated Fault
65
0
KP-5
950
550
h
55
h h h
Mineral Deposits ( 2
60
h
SMM
N
4239500
Precambrian schists and gneisses
Eocene high pressure metamorphism belt
4238000
Denizli
4239000
Menderes Massif (MM)
Cycladic Core Complex
h
37° E
BMD
650
h
Samos
Metamorphic Core Complexes
65
h
BMG
CMM
Mid-Late Jurassic ophiolitic mélange
0
Kaleb Boucher
4 Vein Paragenesis
0 95
Cycladic Islands
Palaeozoic to Mesozoic accretionary terrane
500
900
0 95
Seferihisar Highlands (Figure 2)
Palegonian Zone (PZ)
h
KMG
Sakarya Zone (SZ)
8
(3)
650
64
1
Mesozoic carbonates
h h h h
AD
Permo-Triassic blueschists
h
Chois
NMM
h
Izmir
Uşak
Map modified from TÜPRAG Metal Madencilik Sanayi ve Ticaret A.S. by Kaleb Boucher
Lycian Nappes (LN)
64
ay
GG
Tavşanlı Zone (TZ)
hh
3
47
Manisa
ir B Izm
2
Palaeozoic mixed carbonate- clastics
Upper Cretaceous ophiolitic mélange
h h
SD
Mediterranean Sea
Afyon Zone (AZ)
h
h hhh h h
Lesbos
Bornova Flysch and Karaburun Belt (BFZ)
600
h
Tectonic Units
B’
(4)
950
h
Iraq
Granitic, granodiorite, to dioritic rocks
70
h h
7
4 Syria
(1)
Miocene lacustrine sedimentary deposits with intercalated felsic volcanics
Eğrigöz Pluton
550
h
Turkey
Miocene Granitoids
h
Kozak Pluton
Cenozoic Volc.-Sed. Basins
h
Balıkesir
0
60
h
5
Edremit Gulf
Tertiary Rocks
500
h
6
Geology of the Efemçukuru Epithermal Au-Deposit
h
29° E
h
28° E
h
Western Anatolian Extensional Province Figure 1
Greece
27° E
26° E
h
Bulgaria
25° E
h hh
Black Sea
Georgia
650
h h
Russia Romania
3 Structural Analysis
2 Geology of Efemçukuru
Introduction & Regional Geology
h h
1
Contact:
I’d like to thank the geologists and geotechs at Tüprag for their tremendous support: most notably Çağlar Acımaz, Orbay Yavuz, Ömer Ilgın, Nadir Arslan, Mustafa Özkayhan, and Özgür Akyürek. I’d also like to thank Aleksandar Mišković, Matías Sánchez, Thomas Bissig, Greg Dipple, Andreas Beinlich, Farhad Bouzari, Craig J.R. Hart, and Tim Baker from Eldorado Gold for their help and guidance with this project. Finally, I’d like to thank my fellow students and colleagues in the Western Tethyan project for their support over the past couple of years.
Main “driving” structure: thick gouge, intermittent veining, large damage zone of faults and fractures. Broad zone of interconnected but thinner difuse, gain-scale porosity. Lower fluid flux.
(Kestanebeleni Vein) Linkage Zone structures: low-displacement, less mature fault, fracture, and vein network. Narrow zones of connected open porosity. Longer lived metalbearing fluid flux.
