Geochemical characteristics and age of metamorphic sole rocks within a Neotethyan ophiolitic mélange from Konya region (central southern Turkey)

Abstract

Palaeo- and Neo-Tethyan-related magmatic and metamorphic units crop out in Konya region in the south central Anatolia. The Neotethyan assemblage is characterized by mélange and ophiolitic units of Late Cretaceous age. They tectonically overlie the Middle Triassic–Upper Cretaceous neritic to pelagic carbonates of the Tauride platform. The metamorphic sole rocks within the Konya mélange crop out as thin slices beneath the sheared serpentinites and harzburgites. The rock types in the metamorphic sole are amphibolite, epidote-amphibolite, garnet-amphibole schist, plagioclase-amphibole schist, plagioclase-epidote-amphibole schist and quartz-amphibole schist. The geochemistry of the metamorphic sole rocks suggests that they were derived from the alkaline (seamount) and tholeiitic (E-MORB, IAT and boninitic type) magmatic rocks from the upper part of the Neotethyan oceanic crust. Four samples from the amphibolitic rocks yielded ⁴⁰Ar/³⁹Ar isotopic ages, ranging from 87.04 ± .36 Ma to 84.66 ± .30 Ma. Comparison of geochemistry and geochronology for the amphibolitic rocks suggests that the alkaline amphibolite (seamount-type) cooled below 510 ± 25 °C at 87 Ma whereas the tholeiitic amphibolites at 85 Ma during intraoceanic thrusting/subduction. When all the evidence combined together, the intraoceanic subduction initiated in the vicinity of an off-axis plume or a plume-centered spreading ridge in the Inner Tauride Ocean at 87 Ma. During the later stage of the steady-state subduction, the E-MORB volcanics on the top of the down-going slab and the arc-type basalts (IAT/boninitic) detached from the leading edge of the overriding plate, entered the subduction zone after ~2 my and metamorphosed to amphibolite facies in the Inner Tauride Ocean. Duration of the intraoceanic detachment (~87 Ma) and ophiolite emplacement onto the Tauride-Anatolide Platform (Tavşanlı Zone), followed by subsequent HP/LT metamorphism (~82 Ma) spanned ~5 my in the western part of the Inner Tauride Ocean.

Keywords:

• ophiolite
• metamorphic sole
• Ar–Ar geochronology
• amphibolite
• Konya

Introduction

Konya region in south central Anatolia forms one of the important locations, where both magmatic and metamorphic units resulted from the Palaeotethyan and Neotethyan evolution can be observed. The remnants of Palaeotethyan crop out in the N–NW part of Konya city and are characterised by pre-Permian tectono-stratigraphic/magmatic units (Eren, 1993; Eren, Kurt, Rosselet, & Stampfli, 2004; Göncüoğlu et al., 2007; Özcan, Göncüoğlü, Turhan, Uysal, & Şentürk, 1988; Özcan et al., 1990; Robertson & Ustaömer, 2009, 2011). The Palaeozoic rock assemblage is unconformably covered by Permian and Triassic sedimentary units (Göncüoğlu et al., 2007; Özcan et al., 1988; Robertson & Ustaömer, 2009). These rocks are interpreted as a part of the Afyon–Bolkardağ Zone (Okay, 1986) or the Kütahya–Bolkardağ belt (Göncüoğlu, Dirik, & Kozlu, 1996–1997), which experienced Alpine HP–LT metamorphism (Candan, Çetinkaplan, Oberhänsli, & Rimmelé, 2005; Davis & Whitney, 2006; Okay, 1986; Pourteau, Candan, & Oberhänsli, 2010; Pourteau et al., 2013; Sherlock, Kelley, Inger, Harris, & Okay, 1999) (Figure 1), whereas the Neotethyan units crop out mainly in the southwestern part of the Konya city. They are dominated by mélange and ophiolitic units of Late Cretaceous age (Figure 2).

Figure 1. Outline tectonic map of Turkey showing the study area (taken from Robertson & Ustaömer, 2009; tectonic zones are from Okay & Tüysüz, 1999).

Figure 2. Outline geological map (modified from MTA, 2002) showing the Palaeotethyan and Neotethyan units around Konya (taken from Robertson & Ustaömer, 2009).

The harzburgite blocks in the mélange to the SW of Konya locally include metamorphic sole at its base. Initiation of subduction and formation of metamorphic soles have been linked to the ophiolite emplacement process (Hacker, Mosenfelder, & Gnos, 1996; Jamieson, 1980, 1986; Malpas, 1979; McCaig, 1983; Wakabayashi, Ghatak, & Basu, 2010; Williams & Smyth, 1973). The Tethyan ophiolites are structurally underlain by thin sheets of high-grade metamorphic sole rocks (Çelik, 2002; Dilek, Thy, Hacker, & Grundvig, 1999; Jamieson, 1986; Parlak & Delaloye, 1999; Parlak et al., 1995, 2006; Robertson, 2002, 2004; Spray, 1984; Vergili & Parlak, 2005; Williams & Smyth, 1973). Protoliths of the metamorphic soles in Anatolia suggest the presence of both tholeiitic and alkaline magma types from various tectonic settings, such as OIB, MORB and IAB (Çelik, 2002; Çelik & Delaloye, 2003; Elitok & Drüppel, 2008; Lytwyn & Casey, 1995; Parlak, 1996; Parlak et al., 1995, 2006; Polat, Casey, & Kerrich, 1996; Vergili & Parlak, 2005). The ⁴⁰Ar/³⁹Ar ages of the metamorphic soles from the Tauride ophiolites range from 96 Ma to 88 Ma (Çelik, Delaloye, & Feraud, 2006; Dilek et al., 1999; Parlak & Delaloye, 1999; Parlak et al., 2013), whereas the metamorphic sole rocks beneath the ophiolites from the İzmir-Ankara–Erzincan suture zone and its eastward prolongation display variable ⁴⁰Ar/³⁹Ar ages, ranging from 101 Ma to 93 Ma (Harris, Kelley, & Okay, 1994; Önen, 2003) in NW Anatolia, 177 Ma to 167 Ma in NE Anatolia (Çelik et al., 2011) and 90 Ma in NW of Sevan–Akera suture zone (Hassig et al., 2011).

The timing of HP–LT metamorphism of the leading edge of the Anatolides is well constrained in the Tavşanlı Zone from 82.8 Ma to 79.7 Ma based on Rb–Sr dating of phengite (Sherlock et al., 1999). Exhumed leading edge of the Anatolides and emplaced ophiolites were juxtaposed by Late Maastrichtian to Middle Paleocene as these units were unconformably covered by shallow water sediments (Robertson, Parlak, & Ustaömer, 2009).

The scope of this paper is (1) to present petrography and geochemistry of the metamorphic sole rocks and hence to investigate possible protoliths of the accreted material to the base of mantle tectonites during intraoceanic thrusting, (2) to give new ⁴⁰Ar–³⁹Ar age dating of the metamorphic sole rocks and (3) to constrain about the time gap between the intraoceanic subduction and the continental margin subduction during Neotethyan convergence.

Geological setting and petrography

The allochthonous and autochthonous rock assemblages in Konya region are interpreted as part of the Afyon–Bolkardağ Zone (Okay, 1986) or the Kütahya–Bolkardağ belt (Göncüoğlu et al., 1996–1997). The Palaeotethyan units are dominated by a dismembered, latest Silurian–Early Carboniferous carbonate platform (Bozdağ massif), a Carboniferous mélange made up of sedimentary and igneous blocks in a sedimentary matrix (Halıcı Group or Sızma Group), and an overlying earliest Permian volcanic–sedimentary unit (Eren, 1993; Eren et al., 2004; Özcan et al., 1988, 1990; Robertson & Ustaömer, 2009, 2011) (Figure 2). There are number of interpretations about the geodynamics of this assemblage such as (a) an active continental margin bordering the northern margin of Gondwana (Eren & Kurt, 2000), (b) an Early Carboniferous back-arc rift along the northern margin of Eurasia (Göncüoğlu et al., 2007), (c) a fore-arc basin related to northward subduction beneath Eurasia (Eren et al., 2004) and (d) a Carboniferous accretionary complex related to southward subduction beneath Gondwana (Robertson & Ustaömer, 2009, 2011). The Neotethyan assemblages (mélange and ophiolite) tectonically overlies the Middle Triassic–Upper Cretaceous neritic (Loras limestone) to pelagic (Midos Tepe formation) carbonates of the Tauride platform (Özcan et al., 1990) (Figures 2 and 3). The Loras limestone is exposed in Loras mountain in the NW of the study area and generally characterised by medium-to-hick-bedded neritic limestone and dolomitic limestone in a lesser extend (Figure 4(a) and (b)). Based on the fossil evidence, it is Middle Triassic to Cretaceous in age (Özcan et al., 1988). To the west of Konya, the Loras limestone is transitionally followed by the Midos Tepe formation that comprises thin-bedded red pelagic limestones, abundant cherty limestone and radiolarian mudstone in the upper level (Figure 4(c)). This unit is Maastrichtian in age (Özcan et al., 1988). The Tauride Platform is tectonically overlain either by mélange or peridotite body (Figure 3). The mélange unit has both sedimentary and sheared serpentinite matrix in which large blocks of limestones ranging in age from Carboniferous to Late Cretaceous, radiolarian cherts, mudstone and ophiolitic rocks (ultramafic rocks, volcanics, gabbro) are tectonically dispersed (Figure 4(e)–(h)). The mélange unit is structurally overlain by an ophiolite body that is characterized by serpentinised harzburgite with economically important hydrothermal magnesite deposits, dunite, pyroxenite and gabbro (Figure 4(b)–(d)).

Figure 3. Geological map of the Neotethyan units to the southwest of Konya (from Özcan et al., 1990). Cross section showing the tectonic relations of the platform and oceanic assemblages in the study area.

Figure 4. Field views of rock units in the platform and mélange. Loras limestone (a), tectonic relation between Loras limestone and peridotite body (b), pelagic carbonates (Midostepe formation) on the top of the platform (c), serpentinised harzburgite with magnesite veins (d), limestone blocks in the mélange (e), radiolarian cherts and mudstone in the mélange (f), sheared serpentinite in the mélange (g), and volcanogenic sandstone in the mélange (h).

Large harzburgite blocks (Figure 6(a)) within the mélange locally include an attached metamorphic sole (Daşçı, 2007). The metamorphic sole can be observed along a road section between Çayırbağ and Karadiğin villages (Figure 3). The metamorphic sole has ~35 m thickness. The contact between the metamorphic sole and the overlying peridotite is defined by a 2–3-m-thick strongly sheared serpentinite above and amphibolite schist below (Figure 5). The foliation patterns in the serpentinite and the metamorphic sole are concordant, suggesting that the contact can be interpreted as representing the initial intra-oceanic decoupling surface (Spray, 1984) (Figures 5 and 6(b)). The metamorphic sole include the following rock association: amphibolite, epidote-amphibole schist, garnet-amphibole schist, amphibole schist, plagioclase-amphibole schist, plagioclase-epidote-amphibole schist and quartz-amphibole schist (Figure 6). The mineral assemblages in the metamorphic sole rocks are given in Table 1. The metamorphic sole rocks exhibit granoblastic and nematoblastic textures. They display well-developed foliation due to the preferred orientation of hornblende and plagioclase (Figure 6(d) and (e)). Amphibolitic metamorphic soles consist of hornblende-dominated dark layers that alternate with light bands, lenses and stringers composed of plagioclase, epidote and minor quartz (Figure 6(d)–(f)). The amphiboles are the most common phases in the metamorphic sole rocks and represented by euhedral to subhedral hornblendes (65–85%). The plagioclase (15–20%) exhibits strong alteration products including calcite, albite and sericite. The garnets (15–20%) occur as porphyroblasts and are accompanied by hornblende in high-grade rocks (Figure 6(c)). The actinolite is represented by euhedral to subhedral crystals and very common with pronounced needle-like crystals in greenschist facies rocks. The epidote and zoisite are common in lower amphibolite and greenschist facies rocks of the metamorphic sole. The epidote also occurs as veins. Sphene, rutile and opaque minerals are the accessory phases.

Figure 5. Tectonic relation between the sheared serpentinite and metamorphic sole rocks in Karadiğin village.

Figure 6. Rock units in the metamorphic sole and overlying peridotite. Serpentinized harzburgite (a), tectonic contact between the metamorphic sole and the serpentinite (b), garnet-bearing amphibolite (c), plagioclase-amphibole schist (d), amphibolite schist (e), and epidote-amphibole schist (f).

Table 1. Mineral assemblages in the metamorphic sole rocks from the Konya mélange, Turkey.

Sample	Rock type	Hbl	Act	Cpx	Pl	Ep	Qtz	Chl	Ttn	Zrn	Cal	Grt
A-1	Garnet amphibole schist	×	×				×*					×
A-2	Epidote amphibole schist	×				×*			×
A-3	Garnet amphibole schist	×		×		×			×			×
A-4	Garnet amphibole schist	×				×	×		×			×
A-5	Garnet amphibole schist	×				×		×				×
A-6	Plagioclase amphibole schist	×		×	×	×*	×				×
A-7	Amphibole schist	×		×			×			×
A-8	Plagioclase amphibole schist	×			×		×		×		×
A-9	Plagioclase amphibole schist	×			×					×
A-10	Amphibole schist	×					×	×
A-11	Garnet amphibole schist	×	×		×	×*						×
A-12	Epidote amphibole schist	×	×			×					×
A-13	Garnet amphibole schist	×		×	×			×				×
KM-2	Amphibolite										×
KM-3	Garnet amphibole schist	×	×	×					×			×
KM-4	Amphibolite	×			×	×
KM-5	Amphibolite										×
KM-6	Plagioclase amphibole schist	×			×	×		×	×
KM-7	Amphibole schist	×	×	×					×
KM-8	Amphibolite	×				×
KM-9	Amphibolite										×*
KM-11	Plagioclase amphibole schist	×		×	×	×				×
KM-13	Plagioclase amphibole schist	×	×		×	×
KM-16	Amphibolite	×			×
KM-18	Plagioclase amphibole schist	×		×	×			×
KM-19	Plagioclase amphibole schist	×		×					×
KM-20	Epidote amphibole schist	×		×	×	×
KM-21	Plagioclase amphibole schist	×			×		×				×*
KM-22	Plagioclase amphibole schist	×	×		×				×	×
KM-23	Plagioclase amphibole schist	×		×	×	×				×
KM-24	Quartz amphibole schist	×					×	×	×
KM-25	Quartz amphibole schist	×					×	×	×

Note: Hbl: hornblende; Act: actinolite; Cpx: clinopyroxene; Pl: plagioclase; Ep: epidote; Qtz: quartz; Chl: chlorite; Ttn: titanite; Cal: calcite; Grt: garnet. *Veins.

Analytical Method

A total of 27 samples from the metamorphic sole rocks were analysed for major and trace (including rare earths) elements in Acme Analytical Laboratories Ltd. in Canada. Major element contents were determined from a LiBO₂ fusion by ICP-ES by using five grams of sample pulp. Trace element contents were determined from a LiBO2 fusion by ICP-MS by using five grams of sample pulp. The results of the analyses are presented in Tables 2 and 3. ⁴⁰Ar/³⁹Ar geochronology was carried out on handpicked hornblende grains from amphibolites of the metamorphic sole at The Auburn Noble Isotope Mass Analysis Laboratory (ANIMAL).

Table 2. Major and trace element analyses of the metamorphic sole rocks (Group I & II) from the Konya mélange, Turkey.

	I. Group	II. Group
Sample	A8	A-2	A12	A-13	KM-3	KM-4	KM5	KM8	KM10	KM12	KM14	KM18	KM21	KM22	KM23
SiO2	50.84	45.02	44.82	44.56	46.49	44.10	45.18	45.18	44.77	43.66	48.55	44.27	49.14	41.63	44.54
TiO2	1.97	.97	.83	1.21	.75	.66	.73	.45	.62	.76	.53	.97	.65	.84	.71
Al2O3	15.74	14.32	12.06	10.98	9.68	14.98	12.11	13.16	11.50	11.84	8.08	14.53	14.78	15.92	14.99
FeO*	8.93	10.59	11.34	15.40	12.27	10.53	10.92	10.22	12.26	15.02	11.14	11.05	8.66	9.83	9.63
MgO	7.15	13.20	11.63	12.56	14.81	11.56	14.76	13.80	14.54	12.74	15.95	12.72	9.03	10.51	10.43
MnO	.14	.23	.24	.39	.32	.16	.20	.16	.23	.32	.35	.27	.14	.17	.16
CaO	7.63	11.36	15.45	11.53	11.23	14.06	11.28	13.13	12.00	11.48	11.85	12.59	11.25	15.22	15.89
Na2O	4.89	2.23	1.22	1.81	2.24	1.72	2.37	2.05	2.05	2.23	1.65	1.98	2.38	1.40	1.31
K2O	1.13	.41	.52	.63	.29	.25	.32	.30	.32	.67	.72	.43	2.24	.28	.39
P2O5	.29	.06	.09	.02	.01	.04	.01	.05	.02	.01	.07	.08	.06	.10	.05
Cr2O3	.05	.09	.08	.07	.08	.05	.11	.01	.01	.08	.19	.09	.06	.08	.08
LOI	1.10	1.50	1.70	.80	1.80	1.90	2.00	1.50	1.70	1.20	.90	1.00	1.60	4.00	1.80
Total	99.86	99.98	99.98	99.96	99.97	100.01	99.99	100.01	100.02	100.01	99.98	99.98	99.99	99.98	99.98
Ba	513.00	53.80	18.70	14.00	23.10	11.20	10.50	26.40	14.90	31.10	36.20	23.90	95.30	19.20	27.60
Co	39.3	51.9	55.4	76.9	63.2	56	58.6	52.7	64.3	64.7	75.8	54.5	38.7	46.3	43.8
Cs	.1	<.1	<.1	<.1	<.1	<.1	<.1	<.1	<.1	.1	<.1	<.1	<.1	<.1	<.1
Ga	15.7	13.8	12.6	12.7	10	16.5	11.9	13.6	10.6	11.5	8.8	15	12.8	16.2	14.6
Hf	5.8	1.6	1.2	1.1	2.1	.6	.7	.6	<.5	1.1	.6	1.3	1	1.2	.9
Nb	40.2	2.1	1	3.6	5.1	.9	2.1	.7	1.1	2	1.7	1.9	.8	2	1.1
Rb	11.2	3.9	2.3	1.2	<.5	.7	.9	.8	1.1	1.6	5.9	3	29.1	1.6	3
Sr	454.6	35.8	55.4	28.7	17.4	157.3	25	148.3	36.8	33.5	27	67.5	128.1	190.4	198.3
Ta	2.4	.1	<.1	.1	.3	<.1	<.1	<.1	<.1	<.1	<.1	.1	<.1	.1	<.1
Th	4.3	.3	.9	.1	.5	.2	.6	.5	.2	.8	<.1	.3	.1	.4	<.1
U	1.7	<.1	<.1	<.1	<.1	<.1	.1	.2	.1	.1	<.1	.2	<.1	.2	<.1
V	175	258	245	277	177	278	251	237	237	145	176	252	213	244	231
W	1.3	.2	.1	.2	.1	.1	.3	.1	.4	.1	.1	.1	.1	<.1	.1
Zr	243.9	51.3	28.7	24.7	69.2	16.9	14	12.4	10.6	39.2	14	43.5	29.6	35.6	25
Y	26.7	22.3	24.8	35.8	26.5	19.4	16.4	19	13.1	23	22.4	29.2	18.4	29.1	20.6
Pb	1.4	.2	.3	.2	.5	.4	.2	.4	.2	.3	.3	.1	.3	.5	.3
Ni	32.1	36.8	16.1	42.8	68.5	33.9	59.3	27.8	21.7	45.4	30.4	50.5	31.8	40.1	20.3
Sc	27.00	39.00	46	48.00	37.00	47.00	49	50	49	45	47.00	43.00	35.00	39.00	40.00
La	37.7	1.5	9.1	2.1	2.4	1.6	6	5.1	2.2	9.8	2.2	3.9	2.3	3.2	2.1
Ce	81.7	6.8	19.7	9.4	9	4	11	10	4	18.4	6.3	9.3	4.3	7.6	4.5
Pr	8.68	1.03	2.44	1.83	1.41	.64	1.23	1.31	.62	2.78	1.16	1.52	.73	1.26	.76
Nd	34.4	6.3	10.6	10.5	8.6	4.1	5.7	6	3.6	13.6	7.6	8.5	4.1	7.1	4.4
Sm	6.6	2	2.6	3.7	3	1.4	1.6	1.8	1.4	3.4	2.8	2.8	1.5	2.6	1.7
Eu	2.14	.71	.91	1.08	.79	.7	.56	.98	.61	1	.76	1.15	.61	1.03	.64
Gd	5.44	2.78	3.22	5.14	4.28	2.51	2.13	2.69	1.83	4.19	3.56	4.14	2.36	3.49	2.55
Tb	.97	.57	.63	1.02	.76	.42	.41	.46	.35	.68	.61	.8	.46	.7	.47
Dy	4.78	3.62	4.15	6.34	4.78	3	2.48	3.05	2.36	3.84	3.85	4.99	3.09	4.74	2.97
Ho	.9	.82	.89	1.31	.99	.67	.58	.73	.45	.81	.82	1.06	.64	.98	.7
Er	2.6	2.38	2.72	3.79	2.9	2.06	1.81	1.95	1.4	2.51	2.25	3.15	2.04	3	2.28
Tm	.37	.39	.42	.57	.46	.3	.28	.27	.21	.37	.3	.46	.29	.45	.33
Yb	2.09	2.22	2.43	3.11	2.64	1.81	1.56	1.75	1.26	1.98	1.68	2.62	1.75	2.73	1.95
Lu	.34	.35	.42	.44	.41	.33	.24	.28	.22	.3	.27	.42	.29	.39	.3

^* Total Fe is expressed as FeO.

^< means below detection limit.

Table 3. Major and trace element analyses of the metamorphic sole rocks (Group III & IV) from the Konya mélange, Turkey.

	III. Group						IV. Group
Sample	KM11	KM15	KM16	KM17	KM20	KM24	KM1	KM2	KM6	KM7	KM9	KM13
SiO2	43.75	45.84	47.47	47.94	43.76	66.74	47.41	52.57	51.77	52.77	45.01	43.98
TiO2	1.09	.96	.97	.83	.87	.60	.33	.16	.08	.06	.53	.32
Al2O3	12.24	7.97	7.67	7.14	14.55	4.34	10.15	4.21	4.54	4.07	12.08	15.92
FeO*	12.53	15.69	11.57	11.83	10.27	8.21	10.04	8.33	6.87	6.51	11.63	6.20
MgO	12.52	11.05	12.93	13.87	10.05	10.19	15.76	18.67	21.38	21.01	14.41	12.75
MnO	.23	.56	.41	.40	.17	.37	.20	.32	.17	.16	.19	.12
CaO	13.55	13.74	15.07	14.66	17.15	6.88	11.95	11.74	10.65	10.68	11.81	16.99
Na2O	1.91	1.94	1.75	1.79	1.27	1.06	2.07	1.18	.78	.68	2.48	1.30
K2O	.42	.89	.81	.51	.36	.30	.33	.15	.06	.06	.34	.14
P2O5	.03	.01	.05	.03	.09	.11	.01	.01	.01	.01	.01	.02
Cr2O3	.09	.08	.17	.17	.06	.09	.21	.10	.28	.21	.01	.09
LOI	1.60	1.20	1.10	.80	1.40	1.10	1.50	2.50	3.30	3.60	1.50	2.20
Total	99.96	99.93	99.97	99.97	100.00	99.99	99.96	99.94	99.89	99.82	100.00	100.03
Ba	17.40	71.30	87.40	30.60	13.00	10.10	31.40	24.10	7.10	5.80	20.90	9.10
Co	61.2	80.3	57.2	60.3	45.7	48.2	58.6	57.3	58.1	66.2	59.6	37.1
Cs	<.1	.2	<.1	<.1	<.1	<.1	<.1	<.1	<.1	<.1	<.1	<.1
Ga	13.3	9.8	10.2	9.3	15.1	6.7	8.9	4.9	5.3	4.4	11.2	10.7
Hf	1.3	1.7	1.4	.9	1.5	1.1	.6	.5	<.5	<.5	<.5	<.5
Nb	6	4.7	6	4.2	2.8	7.2	<.5	<.5	<.5	<.5	.8	<.5
Rb	1.1	6.3	4.8	1.9	1.5	2	<.5	<.5	<.5	.5	<.5	<.5
Sr	106.9	43.3	45.1	37.2	200.4	16.6	10.4	10.6	10.9	11.7	23.6	55.3
Ta	.3	.4	.4	.3	.2	.4	<.1	<.1	<.1	<.1	<.1	<.1
Th	2.2	1	1.5	.8	.6	1.3	<.1	<.1	<.1	<.1	.1	<.1
U	.4	<.1	.1	.1	.3	<.1	<.1	<.1	<.1	<.1	<.1	<.1
V	230	155	187	174	217	135	190	86	57	46	247	153
W	.4	.1	.1	.3	.3	.3	.3	.2	.2	.1	<.1	.1
Zr	41.5	42	35	24.9	43.4	36.9	18	11.2	4.2	2	11.1	7.6
Y	36.5	38.5	46.3	33.1	24.2	23.6	6.4	11.7	9.6	3.6	10.9	10.4
Pb	.3	.5	.3	.4	.3	.3	.3	.3	.3	.2	.3	.5
Ni	49	82.3	38.9	52.6	24.3	30.7	77.1	53.5	332.4	531.6	47.5	39.1
Sc	47	44	46	39	39	25	33	15	5	4	51	35
La	13.1	9.2	10.3	8.6	6.4	13.7	<.5	<.5	<.5	1.2	1.6	1.4
Ce	31.6	30.5	31.9	27.5	10.4	33.1	<.5	1.2	.9	1.1	2.3	2.5
Pr	3.82	4.55	4.53	3.82	1.57	3.83	.04	.21	.21	.22	.36	.36
Nd	16.8	21.2	21.7	18.4	8.7	16.4	<.4	1.4	1.7	.7	1.9	2.2
Sm	4.9	5.6	5.9	4.8	2.7	3.7	.1	.8	.8	.3	.7	.7
Eu	1.72	1.5	1.76	1.31	.98	1	.05	.23	.2	.23	.38	.48
Gd	5.64	6.48	7.14	5.51	3.5	4.1	.34	1.38	1.08	.48	1.37	1.33
Tb	1.02	1.1	1.28	.9	.64	.69	.08	.27	.22	.07	.22	.24
Dy	6.1	6.96	8.08	5.49	3.8	4.21	.72	1.84	1.52	.45	1.73	1.65
Ho	1.3	1.43	1.64	1.2	.81	.8	.22	.37	.31	.12	.38	.36
Er	3.71	3.92	4.44	3.23	2.51	2.23	.78	1.17	.9	.33	1.24	1.14
Tm	.54	.59	.64	.49	.36	.37	.15	.17	.15	<.05	.19	.17
Yb	3.14	3.27	3.37	2.56	2.35	1.79	.99	1.13	1.09	.37	1.25	.92
Lu	.44	.49	.51	.42	.35	.26	.14	.2	.14	.05	.18	.14

^* Total Fe is expressed as FeO.

^< means below detection limit.

Four amphibolite samples were collected for ⁴⁰Ar/³⁹Ar geochronology from four different outcrops of metamorphic sole. The samples were selected on the basis of structural setting and petrography.

Selected four amphibolite samples were crushed and sieved (250–180), and hornblende grains were handpicked under the binocular microscope to be free from visible alteration, inclusion or other phases. The selected samples were washed with de-ionized water in ultrasonic cleaner. Around 300 amphibole grains were individually wrapped in domestic Al-foil and placed in Al-irradiation disk with monitor FC-2 (age = 28.02 Ma., Renne et al., 1998) along with CaF₂ flux monitor. All samples and standards were irradiated in McMaster nuclear reactor facility in Hamilton, Ontario, Canada. The laboratory is equipped with a low-volume, high-sensitivity 10-cm radius sector mass spectrometer and automated sample extraction system (Based 50 W Synrad CO₂ laser) for the analysis of samples. The analyses were conducted by incremental heating analysis (IH) of 80 hornblende grains from each sample. All of the statistical ⁴⁰Ar/³⁹Ar ages in this study are quoted at the 95% confidence level, whereas errors in individual measurements are quoted as one standard deviation (1σ). Data reduction and assessment of statistical ages were done using Microsoft Excel and Isoplot (Ludwig, 2003). The full data-set for this study is available in the data repository (Table 4).

Table 4. ⁴⁰Ar/³⁹Ar analytical data for the measured sample.

Steps	P	t	40 V	39 V	38 V	37 V	36 V	Moles 40Ar*	%Rad	R	Age (Ma)	%-sd
A13 (J = .0146094, Size 250–180 μ, Number Grains=~80)
a	1.3	20	.010805 ± .000323	.002103 ± .000033	−.000010− ± .000016	.028745 ± .003832	.000010 ± .000004	9.13E-17	72.89	3.7454	96.11 ± 24.39	25.38
b	1.6	20	.066837 ± .000535	.015041 ± .000154	.000130 ± .000008	.115594 ± .006110	.000051 ± .000009	5.65E-16	77.37	3.4380	88.41 ± 7.62	8.62
c	1.9	20	.097563 ± .000595	.024427 ± .000201	.000146 ± .000009	.170672 ± .005348	.000058 ± .000007	8.25E-16	82.55	3.2973	84.88 ± 4.14	4.88
d	2.2	20	.222867 ± .000389	.056537 ± .000218	.000292 ± .000008	.307747 ± .008304	.000135 ± .000008	1.88E-15	82.04	3.2340	83.28 ± 1.80	2.16
e	2.5	20	.294890 ± .000430	.075325 ± .000510	.000278 ± .000005	.403433 ± .006990	.000161 ± .000005	2.49E-15	83.91	3.2852	84.57 ± 1.19	1.40
f	2.8	20	.248837 ± .000489	.064606 ± .000312	.000334 ± .000010	.344049 ± .008076	.000113 ± .000005	2.10E-15	86.55	3.3334	85.78 ± 1.14	1.33
g	3.1	20	.532334 ± .000829	.131408 ± .000300	.000805 ± .000009	.674378 ± .009532	.000330 ± .000006	4.50E-15	81.67	3.3084	85.16 ± .63	.74
h	3.4	20	.501432 ± .001036	.131927 ± .000830	.000613 ± .000012	.690587 ± .010119	.000234 ± .000006	4.24E-15	86.20	3.2763	84.35 ± .90	1.07
i	3.7	20	.376679 ± .000631	.098945 ± .000671	.000430 ± .000007	.561078 ± .006002	.000195 ± .000006	3.18E-15	84.67	3.2233	83.02 ± 1.04	1.25
j	4.0	20	.274895 ± .000465	.070502 ± .000335	.000347 ± .000009	.377842 ± .021938	.000146 ± .000006	2.32E-15	84.35	3.2889	84.66 ± 1.40	1.66
k	4.3	20	.536133 ± .001621	.139615 ± .000304	.000733 ± .000012	.753947 ± .009689	.000260 ± .000008	4.53E-15	85.69	3.2907	84.71 ± .87	1.03
l	4.6	20	.331096 ± .000539	.086056 ± .000215	.000502 ± .000008	.472298 ± .006927	.000162 ± .000008	2.80E-15	85.54	3.2912	84.72 ± 1.29	1.52
m	4.9	20	.379542 ± .001106	.100512 ± .000349	.000593 ± .000017	.522707 ± .006691	.000166 ± .000007	3.21E-15	87.06	3.2876	84.63 ± 1.07	1.26
n	5.2	20	.411046 ± .000875	.108603 ± .000509	.000560 ± .000008	.569326 ± .008697	.000173 ± .000007	3.47E-15	87.58	3.3148	85.32 ± 1.12	1.31
o	5.5	20	.224414 ± .000369	.059947 ± .000131	.000317 ± .000010	.306069 ± .005434	.000100 ± .000007	1.90E-15	86.86	3.2515	83.72 ± 1.73	2.07
p	5.8	20	.036571 ± .000439	.009776 ± .000118	.000047 ± .000006	.051204 ± .004574	.000036 ± .000009	3.09E-16	71.31	2.6679	68.98 ± 1.10	14.64
q	6.1	20	.100845 ± .000483	.025924 ± .000102	.000152 ± .000007	.175783 ± .004549	.000082 ± .000009	8.53E-16	76.10	2.9604	76.39 ± 4.03	5.28
A12 (J = .0146094, Size 250–180 m, Number Grains=~80)
a	1.0	20	.002734 ± .000307	.000195 ± .000051	.000006 ± .000011	−.004564 ± .006136	−.000010 ± −.000010	2.31E-17	212.57	29.8239	652.46 ± 352.06	53.96
b	1.3	20	.027539 ± .000315	.004520 ± .000064	.000038 ± .000006	.016820 ± .006601	.000060 ± .000006	2.33E-16	35.97	2.1915	56.85 ± 12.53	22.03
c	1.6	20	.112996 ± .000255	.018166 ± .000108	.000111 ± .000007	.079762 ± .009985	.000194 ± .000008	9.55E-16	49.23	3.0621	78.95 ± 4.24	5.37
d	1.9	20	.200638 ± .000348	.050075 ± .000381	.000215 ± .000009	.185467 ± .009914	.000121 ± .000006	1.70E-15	82.16	3.2919	84.74 ± 1.53	1.81
e	2.2	20	.253207 ± .000317	.058267 ± .000161	.000198 ± .000005	.226944 ± .011378	.000204 ± .000008	2.14E-15	76.14	3.3087	85.16 ± 1.46	1.71
f	2.5	20	.645087 ± .000705	.164341 ± .000622	.000434 ± .000005	.590305 ± .011077	.000340 ± .000008	5.45E-15	84.41	3.3132	85.28 ± .68	.79
g	2.8	20	.594728 ± .000890	.151155 ± .000548	.000470 ± .000008	.540248 ± .013531	.000327 ± .000008	5.03E-15	83.74	3.2946	84.81 ± .75	.88
h	3.1	20	.523459 ± .001457	.122861 ± .000422	.000376 ± .000006	.440085 ± .017606	.000390 ± .000008	4.43E-15	78.00	3.3234	85.53 ± .88	1.03
i	3.4	20	.496065 ± .000932	.116546 ± .000379	.000407 ± .000010	.410244 ± .007378	.000375 ± .000010	4.19E-15	77.66	3.3055	85.08 ± .94	1.10
j	3.7	20	.497459 ± .000626	.120493 ± .000545	.000448 ± .000009	.429757 ± .009570	.000322 ± .000006	4.21E-15	8.89	3.3397	85.94 ± .77	.90
k	4.0	20	.541873 ± .001040	.131404 ± .000328	.000457 ± .000008	.470158 ± .021619	.000381 ± .000008	4.58E-15	79.23	3.2673	84.12 ± .77	.91
l	4.3	20	.685748 ± .001409	.178238 ± .000669	.000431 ± .000010	.657163 ± .018965	.000317 ± .000008	5.80E-15	86.34	3.3217	85.49 ± .72	.84
m	4.6	20	.664350 ± .001192	.178539 ± .000455	.000475 ± .000008	.641416 ± .014274	.000252 ± .000008	5.62E-15	88.81	3.3047	85.06 ± .64	.75
n	4.9	20	.642486 ± .001367	.168186 ± .000395	.000673 ± .000013	.615866 ± .020125	.000281 ± .000006	5.43E-15	87.08	3.3266	85.61 ± .58	.68
o	5.2	20	.655631 ± .000763	.177249 ± .000514	.000549 ± .000010	.614839 ± .019453	.000226 ± .000005	5.54E-15	89.82	3.3223	85.50 ± .56	.65
p	5.5	20	.447639 ± .001138	.122576 ± .000462	.000482 ± .000014	.404449 ± .015591	.000144 ± .000005	3.78E-15	9.52	3.3058	85.09 ± .72	.85
q	5.8	20	.366591 ± .001173	.099963 ± .000160	.000234 ± .000004	.362940 ± .011636	.000118 ± .000005	3.10E-15	9.49	3.3186	85.41 ± .82	.95
r	6.1	20	.157532 ± .000246	.043072 ± .000380	.000117 ± .000005	.130396 ± .014663	.000054 ± .000004	1.33E-15	89.83	3.2854	84.58 ± 1.64	1.94
s	6.5	20	.644607 ± .001419	.172150 ± .000639	.000440 ± .000008	.579943 ± .011234	.000243 ± .000006	5.45E-15	88.86	3.3274	85.63 ± .60	.70
t	7.0	20	.048120 ± .000359	.013140 ± .000124	.000033 ± .000003	.039288 ± .006234	.000024 ± .000005	4.07E-16	85.34	3.1254	8.55 ± 4.30	5.34
u	7.5	20	.024293 ± .000451	.006279 ± .000061	.000022 ± .000003	.019427 ± .005297	.000015 ± .000004	2.05E-16	81.94	3.1698	81.67 ± 7.11	8.71
A2 (J = .0146094, Size 250–180 m, Number Grains=~80)
a	1.0	20	.000287 ± .000218	.000007 ± .000014	−.000026- ± .000010	.001739 ± .005190	−.000012- ± .000011	2.43E-18	1287.54	543.4607	3951.82 ± 6858.37	173.55
b	1.3	20	.011183 ± .000274	.002173 ± .000038	.000009 ± .000002	.017942 ± .004666	.000010 ± .000004	9.45E-17	74.89	3.8541	98.82 ± 24.10	24.39
c	1.6	20	.125941 ± .000702	.032349 ± .000103	.000130 ± .000005	.147803 ± .009789	.000060 ± .000005	1.06E-15	85.83	3.3415	85.99 ± 2.14	2.49
d	1.9	20	.065522 ± .000451	.015666 ± .000088	.000045 ± .000003	.060273 ± .006703	.000047 ± .000006	5.54E-16	78.61	3.2879	84.64 ± 3.93	4.64
e	2.2	20	.079401 ± .000465	.021161 ± .000144	.000007 ± .000001	.092964 ± .012315	.000039 ± .000005	6.71E-16	85.59	3.2114	82.72 ± 3.13	3.79
f	2.5	20	.059457 ± .000435	.013161 ± .000112	.000040 ± .000003	.063509 ± .011242	.000063 ± .000005	5.03E-16	68.77	3.1071	8.09 ± 4.59	5.73
g	2.8	20	.201524 ± .000450	.050792 ± .000476	.000284 ± .000017	.229761 ± .014274	.000102 ± .000006	1.70E-15	85.09	3.3763	86.86 ± 1.91	2.20
h	3.1	20	.148187 ± .000484	.037681 ± .000175	.000179 ± .000006	.163568 ± .008151	.000074 ± .000005	1.25E-15	85.21	3.3509	86.22 ± 1.83	2.12
i	3.4	20	.170650 ± .000775	.043451 ± .000125	.000181 ± .000006	.194638 ± .014609	.000096 ± .000005	1.44E-15	83.46	3.2779	84.39 ± 1.64	1.95
j	3.7	20	.449197 ± .001399	.116530 ± .000252	.000428 ± .000007	.483888 ± .010952	.000226 ± .000008	3.80E-15	85.12	3.2812	84.47 ± .91	1.08
k	4.0	20	.233297 ± .000321	.056949 ± .000235	.000191 ± .000005	.271318 ± .019421	.000151 ± .000005	1.97E-15	80.83	3.3114	85.23 ± 1.36	1.60
l	4.3	20	.241931 ± .000385	.061098 ± .000215	.000211 ± .000004	.281897 ± .005763	.000120 ± .000004	2.05E-15	85.40	3.3816	87.00 ± .93	1.07
m	4.6	20	.229076 ± .000382	.060083 ± .000178	.000172 ± .000006	.260297 ± .005644	.000099 ± .000005	1.94E-15	87.27	3.3273	85.63 ± 1.18	1.38
n	4.9	20	.234013 ± .000438	.059649 ± .000257	.000148 ± .000004	.291037 ± .015052	.000115 ± .000005	1.98E-15	85.45	3.3522	86.26 ± 1.27	1.48
o	5.2	20	.161281 ± .000495	.040686 ± .000381	.000162 ± .000006	.187403 ± .013329	.000088 ± .000005	1.36E-15	83.91	3.3263	85.61 ± 1.93	2.25
p	5.5	20	.165319 ± .000708	.043479 ± .000171	.000116 ± .000003	.193628 ± .004832	.000080 ± .000006	1.40E-15	85.77	3.2613	83.97 ± 1.86	2.21
q	5.8	20	.191760 ± .000457	.049121 ± .000263	.000170 ± .000007	.222243 ± .007805	.000092 ± .000005	1.62E-15	85.77	3.3484	86.16 ± 1.35	1.56
r	6.1	20	.192592 ± .000365	.051016 ± .000219	.000169 ± .000004	.219413 ± .006771	.000073 ± .000004	1.63E-15	88.73	3.3498	86.20 ± 1.25	1.45
s	6.5	20	.192592 ± .000365	.051741 ± .000331	.000161 ± .000004	.219413 ± .006771	.000073 ± .000004	1.63E-15	88.73	3.3028	85.02 ± 1.32	1.55
t	7.0	20	.166223 ± .000334	.044020 ± .000225	.000142 ± .000002	.182999 ± .014630	.000065 ± .000004	1.41E-15	88.38	3.3375	85.89 ± 1.57	1.83
u	7.5	20	.247793 ± .000420	.067136 ± .000381	.000214 ± .000006	.304439 ± .019018	.000080 ± .000005	2.09E-15	90.47	3.3391	85.93 ± 1.43	1.66
A8 (J = .0146094, Size 250–180 m, Number Grains=~80)
a	1.0	20	.003100 ± .000191	.000463 ± .000027	.000012 ± .000008	.003699 ± .008066	−.000005- ± .000007	2.62E-17	147.06	9.8513	242.58 ± 101.02	41.64
b	1.3	20	.179471 ± .000357	.043307 ± .000230	.000134 ± .000006	.166025 ± .010062	.000122 ± .000006	1.52E-15	79.93	3.3126	85.26 ± 1.71	2.01
c	1.6	20	.438351 ± .001289	.115345 ± .000227	.000336 ± .000006	.438547 ± .021414	.000178 ± .000005	3.71E-15	87.98	3.3436	86.04 ± .77	.89
d	1.9	20	.631955 ± .001016	.167796 ± .000397	.000401 ± .000003	.650491 ± .019601	.000201 ± .000006	5.34E-15	90.59	3.4116	87.75 ± .62	.70
e	2.2	20	.322182 ± .000640	.086624 ± .000637	.000103 ± .000006	.355971 ± .012491	.000069 ± .000007	2.72E-15	93.67	3.4838	89.56 ± 1.74	1.95
f	2.5	20	.323589 ± .001155	.086624 ± .000637	.000103 ± .000006	.355971 ± .012491	.000120 ± .000005	2.74E-15	89.06	3.3267	85.62 ± 1.21	1.42
g	2.8	20	.217923 ± .000369	.058028 ± .000272	.000150 ± .000005	.228802 ± .015252	.000086 ± .000005	1.84E-15	88.29	3.3158	85.34 ± 1.39	1.63
h	3.1	20	.328535 ± .000510	.085266 ± .000404	.000271 ± .000007	.353551 ± .012798	.000109 ± .000005	2.78E-15	90.18	3.4746	89.33 ± 1.02	1.14
i	3.4	20	.084774 ± .000454	.022467 ± .000166	.000101 ± .000004	.077909 ± .010306	.000033 ± .000004	7.17E-16	88.57	3.3420	86.00 ± 2.42	2.81
j	3.7	20	.086264 ± .000406	.022467 ± .000166	.000101 ± .000004	.077909 ± .010306	.000033 ± .000004	7.29E-16	88.77	3.4083	87.67 ± 2.41	2.75
k	4.0	20	.144368 ± .004943	.037432 ± .001346	.000229 ± .000013	.144577 ± .008674	.000057 ± .000004	1.22E-15	88.29	3.4053	87.59 ± 5.21	5.95
l	4.3	20	.057496 ± .004874	.016272 ± .001011	−.000037- ± .000011	.066638 ± .012338	.000013 ± .000002	4.86E-16	93.38	3.2993	84.93 ± 10.08	11.87
m	4.6	20	.089341 ± .000518	.023674 ± .000236	.000075 ± .000006	.102810 ± .012662	.000047 ± .000004	7.55E-16	84.46	3.1874	82.11 ± 2.72	3.31
n	4.9	20	.036492 ± .000220	.009139 ± .000073	.000027 ± .000003	.045541 ± .006494	.000017 ± .000004	3.08E-16	86.60	3.4580	88.91 ± 5.93	6.67
o	5.2	20	.031483 ± .000246	.008431 ± .000106	.000021 ± .000002	.033293 ± .003634	.000015 ± .000004	2.66E-16	86.18	3.2180	82.88 ± 5.62	6.78
p	5.5	20	.044274 ± .000280	.011045 ± .000079	.000065 ± .000006	.050456 ± .008654	.000023 ± .000004	3.74E-16	84.40	3.3833	87.04 ± 4.70	5.40
q	5.8	20	.044274 ± .000280	.011045 ± .000079	.000065 ± .000006	.050456 ± .008654	.000023 ± .000004	3.74E-16	84.40	3.3833	87.04 ± 4.70	5.40

Geochemistry

The major and trace (including rare earths) element contents of the metamorphic sole rocks from the Konya mélange are presented in Tables 2 and 3. Most of the metabasic rocks (amphibolite) show varying degrees of alteration from greenschist to amphibolite facies in the studied samples. Even mild alteration may cause selected element mobility, especially involving the large ion lithophile (LIL) elements (e.g. Na, K, Rb, Sr and Ba) (Thompson, 1991). To test element mobility on the studied samples, Sr and Ba are plotted against Zr in Figure 7. These elements display non-systematic scattered distribution, reflecting their mobility. Therefore, characterization and discrimination of the metamorphic sole rocks (amphibolites) have been done on the basis of trace elements generally considered as relatively stable (immobile) during alteration, such as the high field strength (HFS) elements and rare earth elements (Floyd & Winchester, 1978; Pearce & Cann, 1973; Smith & Smith, 1976).

Figure 7. Zr vs. Sr (a) and Ba (b) diagrams for the metamorphic sole rocks, showing the chemical alteration effects.

Overall, the geochemistry of the metamorphic sole rocks from the Konya mélange displays a wide range of chemical variation, which can be grouped into four main magma series: Group I (alkaline serie), Group II (main tholeiitic serie), Group III (enriched tholeiitic serie) and Group IV (low-Ti tholeiitic serie). All the geochemical groups show that the amphibolitic metamorphic sole rocks were derived from an igneous protolith based on the Zr/Ti vs. Ni contents (Figure 8(a)). On the basis of stable incompatible element ratios (Nb/Y vs Zi/Ti) (after Pierce, 1996), the amphibolitic sole rocks represent exclusively metamorphosed tholeiitic basalts, except one sample (A-8) in meta-alkali basalt field (Figure 8(b)). Different petrogenetic groups are well defined by selected major and trace elements in Figure 9. The FeO*/MgO vs. Zr diagram displays a Fe-enrichment trend for the tholeiitic and alkaline groups, resulted largely by mafic fractionation during their genesis (Figure 9(a)). The variations of Y and Ti against Zr show linear positive correlations for the tholeiitic meta-basic rocks (Group II to IV) and differ from the alkaline one (Group I) (Figure 9(b) and (c)). The TiO₂ vs. V diagram in Figure 9(d) differentiate Group I alkaline serie (Ti/V = 67.49), Group II main tholeiitic serie (Ti/V = 11.38–31.42), Group III enriched tholeiitic serie (Ti/V = 24.04–37.13) and Group IV low-Ti tholeiitic serie (Ti/V = 7.82–12.86).

Figure 8. (a) Zr/TiO₂–Ni diagram, demonstrating igneous origin of the metamorphic sole rocks (after Winchester, Park, & Holland, 1980). (b) Zr–Ti vs. Nb–Y rock classification diagram for the metamorphic sole rocks (after Pierce, 1996).

Figure 9. Variation of selected major and trace elements for the metamorphic sole rocks.

Ratio/ratio plots of incompatible elements were used in Figure 10 to characterize mantle source regions for the protoliths of the metamorphic sole rocks from the Konya mélange. Comparative trace element ratios for different geochemical groups of studied rocks were listed with those of MORB’s, ocean island basalts (OIB) and Vanuatu arc lavas in Table 5. The Y/Nb, Y/Ta, Zr/Nb and Ti/Nb ratios of the metamorphic sole rocks suggest that Group I (alkaline serie) is similar to ocean island basalt (OIB) and Group III (enriched tholeiitic serie) is comparable to enriched mid-ocean ridge basalt (E-MORB), whereas Group II (main tholeiitic serie) and Group IV (low-Ti tholeiitic serie) are more akin to normal mid-ocean ridge basalt (N-MORB) (Figure 10(a) and (b)). The Ce/Sm vs. Sm/Yb ratios are plotted in Figure 10(c). The high Sm/Yb and Ce/Sm ratios of the alkaline amphibolite sample (Group I) suggest that it was derived by melting of an OIB-like enriched mantle source, whereas the low Sm/Yb and Ce/Sm ratios of the main tholeiitic serie amphibolites (Group II) and low-Ti tholeiitic serie (Group IV) suggest derivation from a more depleted MORB-like mantle source. The enriched tholeiitic serie amphibolites (Group III) are mainly plotted in the middle, suggesting a more enriched mantle source for their protliths. In the same diagram, it is clearly seen that Group II and Group IV amphibolitic rocks show close similarity to the tholeiitic amphibolites beneath the Tauride ophiolites, whereas Group I amphibolite is more akin to the alkaline amphibolites beneath the Tauride ophiolites (Figure 10(c)). The tholeiitic amphibolites of Group III differ from the metamorphic sole rocks of the Tauride ophiolites.

Figure 10. (a) Y/Nb vs. Y/Ta, (b) Zr/Nb vs. Ti/Nb and (c) Sm/Yb vs. Ce/Sm diagrams, indicating different magma sources for the protoliths of the metamorphic sole rocks. Field of metamorphic soles from the Tauride ophiolites are from Parlak et al. (1995, 2006), Lytwyn and Casey (1995), Çelik and Delaloye (2003), Vergili and Parlak (2005).

Table 5. Comparative trace element ratios for the metamorphic sole rocks (Group I to IV) with those of N-MORB, E-MORB, OIB (from Sun and McDonough (1989)) and IAT (Vanuatu Arc).

Ratios	Group I metamorphic sole rocks	Group II metamorphic sole rocks	Group III metamorphic sole rocks	Group IV metamorphic sole rocks	N-MORB	E-type	OIB	IAT (Vanuatu Arc lavas)
Nb/Y	1.51	.04–.19	.12–.31	.07	.08	.38	1.66	.02–.31
Ti/Y	442.33	141.85–283.73	125.6–215.52	49.95–309.12	271.43	272.73	593.10	193.75–853.83
Th/Yb	2.06	.03–.4	.26–.73	.08	.04	.25	1.85	.07–1.90
Ta/Yb	1.15	.03–.11	.09–.22	–	.04	.20	1.25	.02–.21
Ce/Yb	39.09	2.21–9.30	4.43–18.49	.83–2.97	2.46	6.33	37.04	.31–23.18
Zr/Nb	6.07	6.67–37.00	5.13–15.5	13.88	31.76	8.80	5.83	12.00–76.09
Ti/Zr	48.42	64.97–350.65	97.48–199.83	85.64–286.25	102.70	82.19	61.43	44.68–722.47
Zr/Y	9.13	.63–2.61	.75–1.79	.44–2.81	2.64	3.32	9.66	.59–5.37
Y/Nb	.66	5.20–27.14	3.28–8.64	13.63	12.02	2.65	.60	3.19–41.20
Ba/Nb	12.76	3.89–119.13	1.4–15.17	26.13	2.70	6.87	7.29	15.59–566.67
Rb/Nb	.28	.33–36.38	.18–1.34	–	.24	.61	.65	0–21.39
Th/La	.11	.04–.21	.09–1.17	.06	.05	.10	.11	.02–3.23
Ba/La	13.61	1.75–41.43	.74–8.49	4.83–13.06	2.52	9.05	9.46	9.61–353.13
La/Sm	5.71	.57–3.75	1.64–3.70	2.00–4.00	.95	2.42	3.70	1.11–4.46
Ti/Nb	293.78	881.62–4975.85	499.58–1862.73	3971.69	3261.80	722.89	358.33	915.8–13655.28
Y/Th	6.21	27.33–358.00	16.59–41.38	109.00	233.33	36.67	7.25	5.81–158.46
Y/Ta	11.13	83.33–358	59–121.67	–	212.12	46.81	10.74	48.79–664.52

Notes: Data from Vanuatu Arc Lavas is from Peate et al. (1997)

Data from N-MORB, E-MORB and OIB are from Sun and McDonough (1989)

Chondrite-normalized REE patterns for the four magma series from the metamorphic sole rocks of the Konya mélange, together with data from N-MORB, OIB and E-MORB are presented in Figure 11. The REE concentrations vary from 12 to 159 X condritic for Group I (alkaline amphibolite) rocks. It displays greatest light rare earth element (LREE) enrichment (La_N/Yb_N = 12.94), showing close similarity to ocean island basaltic rocks (Figure 11(a)). The REE concentrations vary from 6 to 41 X condritic for Group II (main tholeiitic amphibolites) rocks. They are generally typified by flat normalized patterns with average (La_N/Yb_N = 1.34), although some have minor LREE depletions and enrichments (Figure 11(b)). The REE concentrations vary from 10 to 58 X condritic for Group III (enriched tholeiitic amphibolites) rocks. They are more enriched (average La_N/Yb_N = 2.84) and display variable degrees of enrichment. These rocks are more akin to E-MORB in Figure 11(c). The REE concentrations vary from .4 to 8 X condritic for Group IV (low-Ti tholeiitic amphibolites) rocks. They are represented by flat REE patterns (average La_N/Yb_N = 1.45) and very depleted compared to N-MORB (Figure 11(d)).

Figure 11. Chondrite-normalized REE diagrams for the metamorphic sole rocks (normalizing values are from Sun and McDonough (1989)).

The N-MORB normalized multi-element diagrams of the amphibolitic metamorphic sole rocks from the Konya mélange are presented in Figure 12, with E-MORB and OIB for comparison. The alkaline amphibolite sample (Group I) in Figure 12a displays a strong progressive enrichment pattern and has more in common with typical enriched ocean island basalt (OIB) composition (Sun & McDonough, 1989). The low-Ti tholeiitic amphibolites (Group IV) show variable, but typically highly depleted patterns compared to N-MORB (Figure 12(d)). The multi-element diagram of the main tholeiitic amphibolites (Group II) exhibits such features as (a) enrichment in LIL (i.e. Rb, Ba, Th and K), (b) strong negative Nb anomaly, (c) depletion in P and Zr, reflecting effects of zircon and apatite fractionation and (d) flat HFS elements compared to N-MORB (Figure 12(b)). The enriched tholeiitic amphibolites (Group III) exhibit progressive enrichment patterns and depletion in Sr, P, Zr, Hf and Ti (Figure 12(c)), showing close similarity to E-MORB (Sun & McDonough, 1989). Negative Sr anomalies represent plagioclase fractionation.

Figure 12. N-MORB normalized spider diagrams for the metamorphic sole rocks (normalizing values are from Sun and McDonough (1989)).

Ar/Ar Geochronology

Four new ⁴⁰Ar/³⁹Ar ages have been obtained from amphibolites of metamorphic sole. The ⁴⁰Ar/³⁹Ar age of each sample is considered to reflect the time of metamorphism in the respective blocks with some variation due to slightly different histories. Hornblendes from the metamorphic rocks yield robust ⁴⁰Ar/³⁹Ar plateau ages (Figure 13). The oldest age was obtained from sample A8, resulted in an age of 87.04 ± .36 Ma (Figure 13(a)). The sample A8 yielded a concordant age as defined by 16 adjacent steps including 97.8% of the total released ³⁹Ar (Figure 13(a)). Samples A12 and A2 yielded a concordant age of 85.26 ± .19 Ma and 85.62 ± .34 Ma, respectively (Figure 13(b) and (c)). The age of sample A12 is defined by steps 3 through 21 including 99.78% of total released ³⁹Ar (Figure 13(c)). The sample A2 yielded a concordant age of 85.62 ± .34 Ma as defined by 20 steps and 100% of the released ³⁹Ar (Figure 13(b)). The youngest hornblende age (A13) was obtained as ⁴⁰Ar/³⁹Ar age of 84.66 ± .30 Ma by 97.8% of the ³⁹Ar, steps 1 through 16 (Figure 13(d)). This sample is slightly, but not significantly younger than other hornblende ages. Calculated Ca/K ratio for each hornblende sample shows that during analyses this ratio was very stable for each sample.

Figure 13. Age spectra diagrams and Ca/K ratios of amphiboles from the metamorphic sole in the Konya mélange.

Discussion

Due to the opening of the South Atlantic Ocean (Dewey, 1988; Smith, Hurley, & Briden, 1981) in Early–Late Cretaceous, rifting ceased and convergence between Afro-Arabian and Eurasia plates began. This compressional tectonic regime caused the initiation of intra-oceanic subduction in the well-established oceanic basins, namely the İzmir-Ankara-Erzincan, the Inner Tauride and the Southern Neotethys. A north-dipping subduction at the beginning of the Late Cretaceous created supra-subduction zone ophiolite bodies in the eastern Mediterranean region (Bağcı, Parlak, & Höck, 2005, 2006, 2008, 2009; Beyarslan & Bingöl, 2000; Parlak, Delaloye, & Bíngöl, 1996, Parlak, Höck, & Delaloye, 2000, Parlak et al., 2013; Pearce, Harris, & Tindle, 1984; Robertson, 2002; Rızaoğlu, Parlak, Höck, & İşler, 2006; Robertson, Parlak, & Ustaömer, 2013; Yalınız, Floyd, & Göncüoğlü, 1996, 2000).The intra-oceanic subduction led to emplacement of several ophiolitic nappes with accreted metamorphic soles and mélanges generally from north to south onto continental margins (Al-Riyami, Robertson, Dixon, & Xenophontos, 2002; Andrew & Robertson, 2002; Dilek & Whitney, 1997; Okay et al., 2006; Önen & Hall, 1993; Parlak & Robertson, 2004; Rice, Robertson, & Ustaömer, 2006; Rice, Robertson, Ustaömer, İnan, & Taslı, 2009; Robertson et al., 2009, 2013; Rojay, 2013; Yılmaz, 1993; Yılmaz, Yiğitbaş, & Genç, 1993).

It has been widely accepted that initiation of subduction and formation of metamorphic soles have been linked to the ophiolite emplacement process (Hacker et al., 1996; Jamieson, 1980, 1986; Malpas, 1979; McCaig, 1983; Williams & Smyth, 1973). Metamorphic soles are thought to form at the inception of oceanic subduction beneath the hot sub-ophiolitic mantle of the hanging wall (Jamieson, 1986; Malpas, 1979; Spray, 1984; Williams & Smyth, 1973). As the metamorphic soles record hot ophiolite emplacement over cold oceanic crust and associated sediments, it is important that the protoliths of the metamorphic soles provide evidence of the nature and composition of former ocean basins (Robertson, 2004).

The amphibolitic rocks of the metamorphic sole from the Konya mélange were derived from the metamorphism of the alkaline and tholeiitic ocean floor basalts. The basaltic rocks and the associated sediments were welded and accreted to the base of ophiolite which formed the hanging wall plate of the subduction zone. The geochemical features of the alkaline amphibolite suggest that it was derived from an enriched mantle source and does not exhibit a subduction-zone component (Figures 10–12). Therefore, it is geochemically similar to seamount-type alkaline basalts. Mesozoic seamount-type alkaline basalts were documented extensively along the Neotethyan sutures in Anatolia (e.g. Çelik & Delaloye, 2003; Dilek et al., 1999; Elitok & Drüppel, 2008; Floyd, 1993; Lytwyn & Casey, 1995; Parlak, 2000; Parlak et al., 1995, 2006; Polat et al., 1996; Rojay, Yalınız, & Atıner, 2001; Vergili & Parlak, 2005), in the Sevan–Akera suture zone in Lesser Caucasus (Rolland et al., 2009) and in the Masirah island ophiolite, Oman (Meyer, Mercolli, & Immenhauser, 1996). Three different tholeiitic amphibolite rocks from the metamorphic sole are defined such as the main tholeiite, the enriched tholeiite and the low-Ti tholeiite suites. The main tholeiite amphibolitic (Group II) rocks display depletion of Nb (Ta), moderate enrichment of LIL elements and parallel to slightly depleted HFS element patterns compared to N-MORB (Figure 12). The negative Nb (Ta) and positive Th anomalies obtained from these rocks indicate a subduction-related tectonic setting for the protoliths. This suggests that island-arc tholeiitic basalts were welded to the base of the over-riding sub-ophiolitic mantle during intraoceanic subduction. Such tholeiitic basaltic volcanic rocks and their metamorphosed equivalents were extensively found in supra-subduction zone-type (SSZ) ophiolites and their subophiolitic metamorphic soles in Turkey (Bağcı & Parlak, 2009; Bağcı et al., 2008; Çelik, 2007; Çelik & Delaloye, 2003, 2006; Çelik et al., 2011; Dilek & Furnes, 2009; Dilek & Thy, 2009; Dilek et al., 1999; Elitok & Drüppel, 2008; Parlak, 1996; Parlak et al., 1995, 2006; Parlak et al., 2000; Rızaoğlu et al., 2006; Vergili & Parlak, 2005; Yalınız et al., 1996, 2000). The enriched tholeiitic amphibolite (Group III) rocks are more akin to E-MORB in terms of rare earth element (REE) and multi-element patterns as well as incompatible element ratios (Figures 11 and 12; Table 5). This suggests that enriched mid-ocean ridge basaltic rocks were accreted to the base of the overriding sub-ophiolitic mantle during intraoceanic subduction. E-MORB protolith is not common from the metamorphic soles of Turkish ophiolites, except the Pozantı-Karsantı ophiolite (Lytwyn & Casey, 1995; Polat et al., 1996). The highly depleted nature of the low-Ti tholeiitic amphibolites (Group IV) in terms of TiO₂ (.06–.53 wt %) and incompatible trace elements (including REEs) as well as the high MgO (13–21 wt %) contents are quite distinctive compared to other groups (Figures 11 and 12; Table 3). Hence, Group IV amphibolites can be compatible with the metamorphosed equivalents of the boninitic volcanic rocks in a fore-arc tectonic setting which are documented in many of the eastern Mediterranean ophiolites (Bağcı & Parlak, 2009; Bağcı et al., 2008; Beccaluva & Serri, 1988; Malpas & Langdon, 1984; Saccani & Photiades, 2004, 2005).

The sub-ophiolitic metamorphic sole rocks from the Konya mélange yielded well-defined plateau ages such as 87.04 ± .36 Ma for alkaline seamount-type amphibolite (A8) and 85.62 ± .34 Ma to 84.66 ± .3 Ma for the IAT-type amphibolites (A2, 12 and 13). This suggests that the metamorphic sole rocks cooled below 510 ± 25 °C (Harrison, 1981) at 87 to 85 Ma during intraoceanic thrusting/subduction. Several alternative models to explain formation of metamorphic sole and ophiolite obduction have been proposed (Agard et al., 2007, 2014; Robertson, 2004; Vaughan & Scarrow, 2003). Comparison of protoliths of the metamorphic sole rocks and the ⁴⁰Ar/³⁹Ar isotopic ages from the Konya mélange suggests that the intra-oceanic subduction initiated in the vicinity of an off-axis plume or a plume-centred spreading ridge in the Inner Tauride Ocean, represented by OIB-type basalts (87.04 ± .36 Ma) because the alkaline amphibolite yielded the older isotopic age than the tholeiitic amphibolites (85.62 ± .34 Ma to 84.66 ± .3 Ma). Similar interpretation has been proposed by Rolland et al. (2009) and Hässig et al. (2011) for the obduction of the Lesser Caucasus Armenian ophiolites along the Sevan-Akera suture zone. During the later stage of the steady-state subduction, a supra-subduction zone (SSZ)-type ophiolite was formed with IAT- and boninitic-type volcanics in the upper part of the overriding plate. The E-MORB volcanics on the top of the down-going slab and the sliced- IAT-/boninitic-type volcanics from the upper plate entered the subduction zone after ~2 my and metamorphosed to amphibolite facies in the Inner Tauride Ocean.

High-precision ⁴⁰Ar/³⁹Ar ages for the metamorphic sole rocks of the Tauride belt yielded 93.6 ± .8 to 90.7 ± .5 for the Lycian ophiolite, 91.5 ± 1.9 to 90.9 ± 1.3 Ma for the Beyşehir ophiolite, 92.4 ± 1.3 to 90.4 ± .9 Ma for the Pozantı–Karsantı ophiolite, 96.0 ± .7 to 91.0 ± .8 Ma for the Mersin ophiolite and 89.65 ± .97 to 87.49 ± .48 Ma for the Divriği ophiolite (Çelik et al., 2006; Dilek et al., 1999; Parlak & Delaloye, 1999; Parlak et al., 2013) and 87.04 ± .36 to 84.66 ± .30 Ma for the Konya mélange. The scatter of the cooling ages for the metamorphic soles is ~11 my although they exhibit very narrow age range for the individual ophiolite body. The age scatter may well suggest that (a) the intraoceanic subduction/thrusting did not start at the same time for all oceanic lithospheric slices that are separated by transform faults before their emplacement onto the Tauride platform or (b) oblique subduction caused this age discrepancy along the Tauride belt ophiolites. Figure 14 presents ⁴⁰Ar/³⁹Ar ages for the metamorphic soles of the Neotethyan ophiolites in the eastern Mediterranean ophiolites. It is clear that the cooling ages of the metamorphic soles beneath ophiolites from the different suture zones do not show any consistency. The metamorphic sole ages from the İzmir-Ankara-Erzincan and Sevan-Akera suture zones display large discrepancy (90 to 177 Ma), whereas the metamorphic sole ages from the Tauride belt are more consistent and tightened between 96 Ma and 85 Ma (Figure 14). If we consider that the formation of metamorphic soles is linked to the ophiolite emplacement process (Hacker et al., 1996; Jamieson, 1980, 1986; Malpas, 1979; McCaig, 1983; Williams & Smyth, 1973), then it is difficult to conclude about simultaneous emplacement processes along several oceanic basins in Anatolia during closure events.

Figure 14. ⁴⁰Ar/³⁹Ar ages from the metamorphic soles beneath the eastern Mediterranean ophiolites. Data are from 1- Dilek et al. (1999), 2- Parlak and Delaloye (1999), 3- Çelik et al. (2006), 4- Chan, Malpas, Xenophotos, and Lo (2007), 5- Önen (2003), 6- Harris et al. (1994), 7- Dimo-Lahitte, Monié, and Vergély (2001), 8- Okay et al. (1996), 9- Roddick, Cameron, and Smith (1979), 10- Beccaletto and Jenny (2004), 11- Spray and Roddick (1980), 12- Çelik et al. (2011), 13- Parlak et al. (2013), 14- Hassig et al. (2013), 15- This study. Abbreviations, AO: Antalya Ophiolite; BHO: Beyşehir–Hoyran Ophiolite; DO: Divriği Ophiolite; EO: Eldivan ophiolite; GO: Göksun Ophiolite; IO: İspendere Ophiolite; KO: Kınık Ophiolite; KmO: Kömürhan Ophiolite; LO: Lesvos Ophiolite; MO: Mersin Ophiolite; ORO: Orhaneli Ophiolite; OsO: Osmaniye Ophiolite; PO: Pınarbaşı Ophiolite; PKO: Pozantı-Karsantı Ophiolite; SO: Sevan Ophiolite; KM: Konya mélange; mu: muscovite; hb: hornblende; bi: biotite. (Map modified after Dilek and Flower (2003) and Çelik et al. (2011)).

The HP/LT Anatolides are generally subdivided into the Tavşanlı Zone in the north and the Afyon Zone (also known as the Afyon-Bolkar Dağ Zone) further south (Okay & Tüysüz, 1999). The Tavşanlı Zone experienced higher grade blueschist facies metamorphism than the Afyon Zone (Candan et al., 2005; Davis & Whitney, 2006; Okay, 1986; Pourteau et al., 2010, 2013; Sherlock et al., 1999). The peak metamorphism in the Tavşanlı Zone is dated by Rb–Sr method on white micas (phengite) and yielded 78.5 ± 1.6 to 82.8 ± 1.7 Ma (Sherlock et al., 1999), indicating the passive margin subduction of the Tauride-Anatolide Platform during ophiolite emplacement in NW Turkey. As the initiation of subduction and formation of metamorphic soles have been linked to the ophiolite emplacement process, duration between intraoceanic thrusting and ophiolite emplacement onto the Tauride-Anatolide Platform, followed by subsequent HP–LT metamorphism could be constrained by using the metamorphic sole ages and ages of HP–LT metamorphism. This suggests that the initiation of oceanic lithosphere detachment and final emplacement onto the Tauride-Anatolide Platform spanned ~5 my. Parlak et al. (2013) stated about 8–10 my for the same tectonic process in the eastern part of the Inner Tauride Ocean. This may indicate that duration between inception of intraoceanic subduction and final emplacement onto the continental margin largely depends on how far subduction zone is away from passive continental margin.

Conclusions

The main findings of the present study are as follows.

(1)	The metamorphic sole rocks within the Konya mélange crop out as thin slice beneath the sheared serpentinites and harzburgites. The rock types in the metamorphic sole are amphibolite, epidote-amphibolite, garnet-amphibole schist, plagioclase-amphibole schist, plagioclase-epidote-amphibole schist and quartz-amphibole schist.
(2)	Metamorphic sole preserves remnants of alkaline (seamount) and tholeiitic (E-MORB, IAT- and boninitic-type) magmatic rocks from the upper part of the oceanic crust.
(3)	The alkaline amphibolite (seamount-type) cooled below 510 ± 25 °C at 87 Ma, whereas the tholeiitic amphibolites at 85 Ma during intraoceanic thrusting/subduction.
(4)	The intraoceanic subduction initiated in the vicinity of an off-axis plume or a plume centered spreading ridge in the Inner Tauride Ocean at 87 Ma. During the later stage of the steady-state subduction, the E-MORB volcanics on the top of the down-going slab and the arc-type basalts (IAT/boninitic) detached from the leading edge of the overriding plate entered the subduction zone after ~2 my and metamorphosed to amphibolite facies within the Inner Tauride Ocean.
(5)	Duration of the intraoceanic detachment (~87 Ma) and ophiolite emplacement onto the Tauride-Anatolide Platform, followed by subsequent HP–LT metamorphism (~82 Ma) spanned ~5 my in the western part of the Inner Tauride Ocean.

Acknowledgements

This work is a part of MSc study of first author who acknowledges financial support from the Çukurova University Research Foundation (Project No: MMF2005YL31). Erdin Bozkurt, Yann Rolland and Yener Eyüboğlu are thanked for their valuable comments that improved the quality of the paper.