Journal of Asian Earth Sciences 90 (2014) 137–148

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Journal of Asian Earth Sciences

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Geochemical characteristics of the Kuh-e Dom intrusion,Urumieh–Dokhtar Magmatic Arc (Iran): Implications for sourceregions and magmatic evolution

http://dx.doi.org/10.1016/j.jseaes.2014.04.0261367-9120/� 2014 Elsevier Ltd. All rights reserved.

⇑ Corresponding author. Tel.: +98 2161112493; fax: +98 2166491623.E-mail address: kananian@khayam.ut.ac.ir (A. Kananian).

Ali Kananian a,⇑, Fatemeh Sarjoughian b, Alireza Nadimi c, Jamshid Ahmadian d, Wenli Ling e

a School of Geology, College of Science, University of Tehran, P.O. Box 14155-6455, Tehran, Iranb Department of Earth Sciences, Faculty of Sciences, University of Kurdistan, Sanandaj, Iranc Department of Geology, Faculty of Science, University of Isfahan, P.O. Box 81746-73441, Isfahan, Irand Department of Geology, Payame Noor University, P.O. Box 19395-3697, Tehran, Irane Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, PR China

a r t i c l e i n f o

Article history:Received 16 September 2013Received in revised form 24 April 2014Accepted 28 April 2014Available online 9 May 2014

Keywords:PetrogenesisSubductionUrumieh–Dokhtar Magmatic ArcCentral Iran

a b s t r a c t

The Kuh-e Dom Pluton is located along the central northeastern margin of the Urumieh–Dokhtar Mag-matic Arc, spanning a wide range of compositions from felsic rocks, including granite, granodiorite,and quartz monzonite, through to intermediate-mafic rocks comprising monzonite, monzodiorite, dio-rite, monzogabbro, and gabbro. The Urumieh–Dokhtar Magmatic Arc forms a distinct linear magmaticcomplex that is aligned parallel with the orogenic suture of the Zagros fold-thrust belt. Most samples dis-play characteristics of metaluminous, high-K calc-alkaline, I-type granitoids. The initial isotopic signa-tures range from eNd (47 Ma) = �4.77 to �5.89 and 87Sr/86Sr(i) = 0.7069 to 0.7074 for felsic rocks andeNd (47 Ma) = �3.04 to �4.06 and 87Sr/86Sr(i) = 0.7063 to 0.7067 for intermediate to mafic rocks. Thisgeochemical and isotopic evidence support a mixed origin for the Kuh-e Dom hybrid granitoid with arange of contributions of both the crust and mantle, most probably by the interaction between lowercrust- and mantle-derived magmas. It is seem, the felsic rocks incorporate about 56–74% lower crust-derived magma and about 26–44% of the enriched mantle-derived mafic magma. In contrast, 66–84%of the enriched mantle-derived mafic magma incorporates 16–34% of lower crust-derived magma to gen-erate the intermediate-mafic rocks. According to the differences in chemical composition, the felsic rockscontain a higher proportion of crustal material than the intermediate to mafic ones. Enrichment in LILEsand depletion in HFSEs with marked negative Nb, Ba, and Ti anomalies are consistent with subduction-related magmatism in an active continental margin arc environment. This suggestion is consistent withthe interpretation of the Urumieh–Dokhtar Magmatic Arc as an active continental margin during subduc-tion of the Neotethys oceanic crust beneath the Central Iranian microcontinent.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction

The geology of Iran provides one of the world’s best examples ofa younger continent–continent collision (Morley et al., 2009). Theongoing collision between the Arabian and Eurasian plates pro-duced the Zagros Orogen (e.g., Stöcklin, 1968; Falcon, 1974) anddeformation of the area between the Aegean Sea, eastern Iran,northern Caucasus–Kopeh Dagh Mountains, and the Persian Gulf(Fig. 1A).

The Zagros Orogen extends from the Turkish–Iranian border inthe NW to the Makran area in the SE. This orogenic belt is

subdivided into several tectonic units; from southwest to northeast,they are the Zagros Fold–Thrust Belt (ZFTB), the Sanandaj–SirjanZone (SSZ), and the Urumieh–Dokhtar Magmatic Arc (UDMA;Fig. 1A) (e.g., Stöcklin, 1968; Berberian and King, 1981; Alavi,1994; Agard et al., 2005). Crustal shortening and folding is concen-trated within the Iranian Plateau, mainly across the Alborz defor-mation belt and the Zagros Orogen. The climax of the orogeny,indicated by the Alborz and Zagros uplifts and the South Caspiansubsidence, took place during the Late Neogene (e.g., Stöcklin,1968; Falcon, 1974; Alavi, 1994).

There has been considerable debate about the relationshipsbetween magmatism and the final suturing of Arabia and Eurasia.Suturing has been estimated to begin in the Late Cretaceous(Berberian and King, 1981), to Early to Middle Eocene (Ghasemi

Fig. 1. (A) Tectonic zones of the Zagros Orogenic Belt: UDMA – Urumieh–Dokhtar Magmatic Arc, SSZ – Sanandaj–Sirjan Zone, MZT – Main Zagros Thrust, CIM – Central IranianMicrocontinent, GKF – Great Kavir Fault and NDF – Nain–Dehshir Fault (modified from Nadimi, 2010). (B) Major structural blocks of the Kuh-e Dom area and its map-scalefault pattern in the northern margin of UDMA draped over shaded-relief SRTM image. QZF – Qom–Zefreh Fault.

138 A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148

and Talbot, 2006), Late Eocene (Allen and Armstrong, 2008; Allen,2009), Late Eocene–Oligocene (Agard et al., 2005), Early to MiddleMiocene (McQuarrie et al., 2003), and Miocene (Mohajjel et al.,2003), although oceanic subduction continued throughout theseperiod.

The subduction-related regions are undoubtedly the most com-plex tectonic provinces on the Earth (Wilson, 1989) and most gran-itoid magmas have been modified by different processes prior toemplacement and crystallization. However, the relative impor-tance of fractional crystallization versus partial melting and therole of open system processes (magma mixing, assimilation) inthe genesis of these rocks is difficult to quantify.

Although the relation with a subduction is clear in UDMA (e.g.,Berberian and King, 1981; Agard et al., 2005), but the parentalmagma and the processes of UDMA magma production remainscontroversial. For example, Haschke et al. (2010) have recentlyreported that Natanz intrusive rocks may be originally producedby delamination or foundering of the lower continental crust intounderlying mantle, as a precursor to the genesis of the Natanzintrusion. Also Ahmadian (2012) and Ahmadian et al. (underreview) suggest that the Kal-e-Kafi intrusive complex was

probably derived by partial melting of delaminated lower crustwith garnet amphibolite composition.

The Kuh-e Dom intrusion is located in the central part of thenortheastern margin of the UDMA. The geologic importance of thisbelt (UDMA) to the geotectonic evolution is well known and thatpetrology was first studied in this area further warrants a moredetailed analysis of this region. Therefore this paper focuses onfurther describing the petrology, geochemistry, and isotopicattributes of the Kuh-e Dom pluton to interpret the key magmaticprocesses involved in its genesis. A comparison of these geochem-ical results with other data from the Natanz and Kal-e-Kafi intru-sions to shed light on this period of magmatism in the UDMAthen ascertain their relationship with UDMA and Neo-Tethyssubduction.

2. Analytical techniques

Twenty-four samples representing felsic and intermediate tomafic rocks from the Kuh-e Dom intrusion were selected on thebasis of their mineralogy, texture, and areal distribution. Analyses

A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148 139

were conducted using the freshest samples in the studied intru-sions. Each sample was prepared by crushing with a jaw crasher,and then grinding to pulp in a steel ball mill. Special care was takento avoid cross contamination by properly cleaning the equipmentafter the preparation of each sample. Some major elements wereanalyzed by X-ray fluorescence (XRF) (Rigaku RIX 2000) using afused glass disk at Naruto University in Japan. Glass beads wereprepared with a sample-to-flux (Li2B4O7) ratio of 1:10 and ana-lyzed for major elements using fundamental parameter-basedspectrometry. The analytical errors were <1%. Some of the major-and trace-element compositions, including REE, were determinedat the ALS Chemex lab, Vancouver, Canada, by ICP-AES andICP-MS, respectively. The analytical accuracy is estimated to bebetter than ±5% for major oxides and ±10% for all trace elements.The details of the chemical procedures are available atwww.alschemex.com.

The Nd and Sr isotopic ratios were analyzed on a Finnigan Tri-ton Thermo-Ionization Mass Spectrometer (TIMS) at the StateKey Laboratory of Geological Processes and Mineral Resources(GPMR), Wuhan, China. The sample powders were digested in Tef-lon bombs using mixed agents of double-distilled HNO3 and HFacids at 190 �C for 48 h. The Nd and Sr elements were separatedand purified in a clean laboratory using ion exchange columns ofDowex AG50WX12 cation resin and Eichrom Ln-Spec resin succes-sively. Isotopic ratios of 143Nd/144Nd and 87Sr/86Sr were normalizedto 146Nd/144Nd = 0.721900 and 88Sr/86Sr = 8.375209, respectively.Measurements of standard La Jolla and SRM NBS987 are in theform of a solution. The 143Nd/144Nd ratio of the La Jolla should beexpressed as 0.511845 ± 0.000003, whereas the 87Sr/86Sr ratio ofthe NBS987 should as 0.710254 ± 0.000008. The ratios of147Sm/144Nd and 87Rb/86Sr were calculated using Sm, Nd, Rb, andSr concentrations determined by ICP-MS.

3. Geotectonic setting

3.1. Urumieh–Dokhtar Magmatic Arc

It is generally assumed that the UDMA was formed above a sub-ducting slab of the Neo-Tethyan oceanic lithosphere that was beingsubducted beneath the Iranian Plate (Alavi, 1994). New constraintsindicate that this convergence has been constant at �2 to 3 cm/year initiation 56 Ma ago, then slowing to <1 cm/year near 25 Ma(Berberian and King, 1981; Davoudzadeh and Schmidt, 1984).The UDMA forms a distinct, linear intrusive-extrusive complexover 4 km thick (Alavi, 1994), which extends along the SSZ andsouth Central Iranian microcontinent (Fig 1A). The UDMA is dom-inated by mafic to felsic volcanic and plutonic rocks (e.g., Berberianand King, 1981). Numerous intrusions are composed of variousrocks, including gabbro, diorite, granodiorite, and granite bodiesof different sizes (e.g., Haghipour and Aghanabati, 1985). Basalticlava flows, basaltic andesites, ignimbrite and pyroclastic rocks,mostly tuff and agglomerate are also widely distributed through-out the UDMA (Alavi, 1994). Geochemical studies indicate thatthe UDMA is composed of subduction-related calc-alkaline andtholeiitic rocks (e.g., Jung et al., 1976; Ahmad and Posht Kuhi,1993). Magmatic activity in the UDMA began in the Eocene andcontinued to Pliocene with its climax in the Middle Eocene(Mohajjel et al., 2003).

3.2. Kuh-e Dom area

The Kuh-e Dom area is located in the northeastern margin ofthe UDMA and the western part of the Central Iranian microconti-nent, in a fault-bounded area, between two deserts (Fig. 1B). Thepluton intruded into Paleozoic phyllites and schists on its western

side, Cretaceous limestone on its western and southern sides, andlower Eocene volcanic rocks on its eastern side (Fig. 2). Petrologi-cally, the intrusion can be divided into the following suites: (1) fel-sic rocks, including granite, granodiorite, and quartz monzoniteand (2) intermediate-mafic rocks, including gabbro, diorite, mon-zogabbro, monzodiorite, and monzonite. These granitoids yieldeda U–Pb isochron age of 47 Ma (Hassanzadeh 2011, personal com-munication). This age is consistent with an earlier Upper EoceneK–Ar age (Technoexport, 1981). The intermediate to mafic rockswith granular texture occur as discontinuous bands surroundingthe northern, southern, and eastern margins of the felsic rocks(Fig. 2). The intermediate to mafic rocks are older than the felsicunits, because (1) the outer zones of the felsic rocks are finegrained and exhibit a chilled margin; (2) in the contact, intermedi-ate to mafic rocks exhibit evidence of epidotization and chloritiza-tion; and (3) the felsic rocks include some xenoliths ofintermediate to mafic host rocks.

It is notable that the felsic rocks include abundant mafic micro-granular enclaves, which consist of diorite, quartz–diorite, monzo-diorite, and quartz–monzodiorite that concentrated in the centerof intrusion. Most of the enclaves are either ellipsoidal or ovoidin shape, 10–20 cm in diameter with chilled margins towards theenclave rims (Sarjoughian et al., 2012).

4. Petrographic features

4.1. Felsic rocks

Felsic rocks are granular, medium grained, and composedmainly of quartz, K-feldspar, plagioclase, biotite, and hornblende,with small amounts of accessory minerals, including titanite, apa-tite, zircon, and opaque minerals (mostly titanomagnetite, hema-tite, pyrite, and chalcopyrite). Quartz and K-feldspar are typicallyanhedral and occur as interstitial phases. Locally, K-feldspar ispresent as large, irregular, poikiolitic grains enclosing fine-grainedplagioclase, hornblende, biotite, and accessory minerals. Plagio-clase occurs as subhedral to euhedral crystals and commonly dis-plays zoning and polysynthetic twins. Plagioclase tends to be anearly, dominant phase. Green hornblende and brown biotite arecommon mafic minerals and form euhedral to subhedral grainsof variable sizes.

4.2. Intermediate to mafic rocks

Intermediate to mafic rocks are granular and medium grained;contain more mafic minerals and plagioclase, and less quartz andK-feldspar compared to the felsic rocks. Quartz and K-feldsparare present in variable proportions. Both minerals are commonlylate interstitial phases, even when the feldspar occurs as largecrystals. Plagioclase occurs as euhedral to subhedral crystals withzoning and polysynthetic twinning. Hornblende and biotite arethe most common mafic minerals, whereas pyroxene occurs as raregrains. Apatite, titanite, and opaque minerals appear as accessoryphases.

4.3. Mafic microgranular enclaves

Mafic microgranular enclaves have plagioclase and ferromagne-sian minerals as predominant phases, although quartz and K-feld-spar are also present. Amphibole is more abundant than biotite inthe enclaves. Quartz and K-feldspar are anhedral interstitialphases. Some larger K-feldspar grains with a poikilitic texture dooccur in the enclaves. Enclaves commonly show sharp contactswith their host granite, and their texture and composition indicateinteraction with the host granite. The contact between the enclaves

Fig. 2. Simplified geological map of the Kuh-e Dom intrusion (Technoexport, 1981) with slight modification.

140 A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148

and the host rock is occasionally diffuse with feldspar megacrystsconcentrated along the enclave margins. These characteristicsmay indicate magma mixing in the Kuh-e Dom intrusion(Sarjoughian et al., 2012).

5. Whole-rock geochemistry

5.1. Major and trace elements

Chemical analyses of representative samples from various unitsof the felsic and intermediate to mafic rocks are listed in Table 1.On a total alkalis against silica diagram (Middlemost, 1994), the

felsic rocks plot in the fields of granite, granodiorite, and quartzmonzonite, whereas the intermediate to mafic rocks plot in thegabbro, diorite, monzogabbro, monzodiorite, and monzonite fields(Fig. 3A).

They are characterized as mildly peraluminous to metalumi-nous based on alumina saturation index (Condie et al., 1999;Fig. 3B) and are medium- to high-K calc-alkaline I-type in compo-sition (Rickwood, 1989; Fig. 3C). Chondrite-normalized REE pat-terns (Sun and McDonough, 1989) of all the intrusive samples(Fig. 4A) essentially have the same shape with light REE (LREE)enrichment (Lan/Ybn = 6.69–17.25), flat heavy REE (HREE) seg-ments (Gdn/Ybn = 1.29–2.19) and significant negative Eu anomalies

Table 1Major, trace elements and isotopic data from the Kuh-e Dom intrusion.

Sample D1 F157 F215 F218 F36 F38 F48 F72 F8 F97 H21 H6Type Qmz Qmz Qmz Gd Gd Gd Gd QMz Gd Gd Gr Qmz

SiO2 66.91 66.30 65.43 65.80 67.30 65.00 63.77 62.68 63.70 66.59 70.60 61.6TiO2 0.50 0.40 0.48 0.44 0.32 0.43 0.55 0.61 0.48 0.47 0.24 0.57Al2O3 15.69 15.25 16.00 15.25 15.70 15.05 16.38 16.15 14.95 15.76 13.85 15.9Fe2O3(T) 2.74 3.93 4.83 4.22 3.26 4.34 5.11 5.69 4.46 4.59 2.68 5.22MnO 0.06 0.07 0.09 0.11 0.04 0.07 0.08 0.08 0.09 0.06 0.03 0.09MgO 1.36 1.22 1.65 1.43 0.90 1.68 1.59 2.11 1.44 1.68 0.79 1.68CaO 4.11 2.66 2.91 3.12 2.12 2.84 4.28 4.13 3.61 3.26 2.01 4.78Na2O 3.85 3.22 3.76 3.33 3.27 3.16 3.53 3.23 3.11 3.62 3.37 3.48K2O 4.64 4.28 4.71 4.15 5.23 3.98 4.52 5.13 3.72 3.81 3.98 3.85P2O5 0.15 0.10 0.15 0.13 0.09 0.12 0.19 0.19 0.15 0.15 0.03 0.15LOI 1.30 1.58 1.60 1.72 1.86 1.17 1.20 1.64 2.00 2.10 0.87 2.97SUM 101.31 99.01 101.61 99.70 100.09 97.84 101.20 101.64 97.71 102.09 98.45 100.29

Ba 648.0 569.0 526.5 534.0 519 685.0 589.0 498.3 560.0 577.0 567.0 546.0Rb 117.0 154.5 156.8 122.5 147.5 146.0 146.0 185.5 122.5 111.0 143.0 146.0Sr 354.0 249.0 279.1 247.0 197.5 295.0 395.0 340.4 263.0 276.0 218.0 354.0Ga 16.70 16.80 N.D# 15.10 14.40 17.30 17.30 N.D# 16.50 16.20 15.10 17.80Nb 15.00 15.10 12.93 13.90 19.90 14.50 17.20 16.16 14.70 13.90 14.50 19.80Hf 4.90 5.10 N.D# 4.60 4.60 4.40 4.80 N.D# 4.70 4.90 3.90 5.70Zr 180 186 171 160 161 160 171 187 164 179 125 207Y 18.50 17.20 22.70 17.70 17.90 19.30 19.10 25.30 17.80 16.20 18.40 27.40Th 16.05 20.10 16.85 16.80 28.60 18.50 22.50 26.79 16.40 15.90 22.50 23.40U 3.00 4.19 N.D# 3.66 5.87 4.01 5.40 N.D# 3.38 3.30 4.58 4.81Cr 10 50 N.D# 40 10 70 20 16 60 10 10 20Ni 6 N.D# 4 N.D# 5 5 9 9 5 6 8 11Co 5.5 44.6 N.D# 35.7 46.0 31.1 13.3 N.D# 38.7 8.6 6.4 10.3V 82 66 N.D# 61 40 75 98 N.D# 73 69 37 118Cu 8 7 N.D# 8 5 6 27 N.D# 9 11 6 50Pb 8 11 10 10 10 12 12 9 11 10 14 12Zn 25 49 N.D# 40 23 61 40 N.D# 53 46 27 32W 14 410 N.D# 351 N.D# 262 24 N.D# 341 7 1 3Ta 1.20 1.50 N.D# 1.30 2.10 1.30 1.30 N.D# 1.30 1.20 1.60 1.60Cs 2.02 4.99 N.D# 3.78 4.41 4.08 7.41 N.D# 3.35 3.27 3.62 6.98La 21.40 36.70 N.D# 32.50 35.30 57.40 37.20 N.D# 31.30 27.70 37.30 31.90Ce 66.10 65.80 39.40 56.60 61.40 100.00 47.30 55.60 56.30 48.50 65.00 61.70Pr 5.27 7.09 N.D# 5.70 6.20 10.50 6.94 N.D# 6.17 5.16 6.48 7.04Nd 19.20 24.70 N.D# 19.40 20.10 34.90 23.30 N.D# 21.60 17.40 20.60 25.60Sm 3.94 4.44 N.D# 3.54 3.58 5.87 4.48 N.D# 4.10 3.28 3.57 5.38Eu 0.98 0.94 N.D# 0.85 0.76 1.08 1.17 N.D# 1.07 0.96 0.67 1.08Gd 3.58 4.19 N.D# 3.69 3.66 5.27 4.34 N.D# 4.09 3.27 3.43 5.01Tb 0.55 0.57 N.D# 0.55 0.52 0.67 0.62 N.D# 0.57 0.49 0.48 0.76Dy 3.44 3.27 N.D# 3.12 3.23 3.82 3.48 N.D# 3.5 3 2.87 4.64Ho 0.62 0.65 N.D# 0.65 0.60 0.72 0.65 N.D# 0.7 0.57 0.59 0.94Er 2.14 2.02 N.D# 1.91 2.05 2.23 2.26 N.D# 2.12 1.90 1.92 2.86Tm 0.31 0.30 N.D# 0.29 0.30 0.33 0.32 N.D# 0.32 0.28 0.30 0.41Yb 2.02 2.13 N.D# 2.07 2.04 2.26 2.09 N.D# 2.22 1.89 2.15 2.88Lu 0.34 0.34 N.D# 0.32 0.34 0.34 0.35 N.D# 0.33 0.32 0.33 0.44Mg# 46.05 36.17 37.15 38.40 32.20 42.14 35.72 39.48 38.43 40.20 34.97 37.7487Sr/86Sr N.D# 0.7079 N.D# 0.7077 0.7079 N.D# N.D# N.D# 0.7077 N.D# N.D# N.D#

143Nd/144Nd N.D# 0.5123 N.D# 0.5124 0.5124 N.D# N.D# N.D# 0.5124 N.D# N.D# N.D#

87Rb/86Sr N.D# 1.7950 N.D# 1.4350 1.4320 N.D# N.D# N.D# 1.3480 N.D# N.D# N.D#

147Sm/144Nd N.D# 0.1087 N.D# 0.1103 0.1017 N.D# N.D# N.D# 0.1147 N.D# N.D# N.D#

(87Sr/86Sr)i N.D# 0.7067 N.D# 0.7067 0.7069 N.D# N.D# N.D# 0.7068 N.D# N.D# N.D#

(143Nd/144Nd)i N.D# 0.5123 N.D# 0.5123 0.5123 N.D# N.D# N.D# 0.5123 N.D# N.D# N.D#

eNd(T) N.D# �5.89 N.D# �4.83 �4.87 N.D# N.D# N.D# �4.78 N.D# N.D# N.D#

Sample S22 F121 F125 F140 F149 F153 F62 H24 H25 H30 S51 S52Type Qmz Md Mz Mgb Di Mz Md Md Gb Di Md Md

SiO2 63.80 54.96 52.10 48.79 57.30 57.10 48.50 54.60 47.20 54.40 53.00 53.80TiO2 0.46 1.01 0.95 1.07 0.79 0.75 0.98 1.00 1.02 0.86 0.94 1.03Al2O3 16.00 19.19 18.30 17.72 16.15 16.50 19.75 19.50 17.60 16.40 16.85 17.10Fe2O3(T) 3.43 7.46 4.89 6.61 7.29 3.77 7.59 6.77 6.69 5.81 3.72 9MnO 0.09 0.10 0.15 0.35 0.13 0.10 0.19 0.13 0.13 0.14 0.21 0.18MgO 1.97 3.75 2.34 2.21 3.82 2.57 2.36 2.81 4.91 4.04 5.10 4.37CaO 3.08 7.00 8.02 14.91 6.64 8.00 8.76 8.00 12.45 8.16 11.35 7.20Na2O 5.00 3.56 3.42 2.42 3.39 3.29 3.13 3.95 3.10 4.56 4.21 3.18K2O 1.80 2.55 3.58 5.52 0.61 3.83 3.09 1.34 1.48 0.83 1.77 3.20P2O5 0.13 0.41 0.38 0.41 0.24 0.24 0.39 0.54 0.47 0.34 0.36 0.41LOI 3.56 3.10 4.88 3.24 4.90 3.50 5.10 1.26 4.74 4.15 2.58 0.50SUM 99.32 103.09 99.01 103.25 101.26 99.65 99.84 99.90 99.79 99.69 100.09 99.97

Ba 290.0 424.0 763.0 374.4 110.5 619.0 460.0 208.0 280.0 123.0 356.0 454.0Rb 73.2 93.4 139.0 184.3 24.0 114.5 113.5 62.7 75.5 35.1 73.1 135.5Sr 312.0 692.0 510.0 430.6 460.0 525.0 518.0 672.0 725.0 460.0 733.0 583.0

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A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148 141

Table 1 (continued)

Sample D1 F157 F215 F218 F36 F38 F48 F72 F8 F97 H21 H6Type Qmz Qmz Qmz Gd Gd Gd Gd QMz Gd Gd Gr Qmz

Ga 16.30 19.90 19.00 N.D# 18.60 18.60 19.80 22.30 19.90 17.90 18.40 20.20Nb 14.80 13.80 14.90 8.54 17.40 18.40 13.80 31.80 11.70 22.20 24.60 27.80Hf 5.10 3.70 3.60 N.D# 5.30 5.30 3.30 4.70 2.40 5.50 6.00 7.30Zr 182 137 133 91 197 193 119 195 85 211 245 294Y 18.20 20.10 25.30 25.80 22.60 25.40 23.40 27.60 22.40 26.50 23.50 26.80Th 18.05 12.35 13.20 10.49 21.20 20.80 12.70 11.35 6.27 13.50 17.60 18.65U 3.04 3.49 5.34 N.D# 4.28 6.03 3.78 5.09 1.81 4.58 4.08 5.53Cr 10 30 50 118.2 90 40 30 66 210 200 80 80Ni 8 13 11 28 26 13 15 32 69 69 24 37Co 8.1 18.6 21.9 N.D# 41.2 36.1 60.0 21.2 19.7 15.4 8.2 27.1V 80 170 173 N.D# 176 150 191 149 296 179 249 242Cu 3 7 5 N.D# 48 13 37 103 29 5 3 106Pb 7 14 7 8.8 7 13 11 21 9 6 170 26Zn 67 46 71 N.D# 63 41 52 83 38 50 494 121W 2 12 75 N.D# 235 236 N.D# 4 1 2 2 5Ta 1.30 1.00 1.10 N.D# 1.40 1.50 1.20 2.20 0.70 1.50 1.60 1.80Cs 3.87 7.52 3.21 N.D# 1.92 4.77 8.09 9.01 5.01 2.38 12.45 9.12La 25.80 25.20 31.30 N.D#* 31.80 27.90 26.80 44.00 25.40 34.70 27.40 41.10Ce 46.00 50.20 59.50 53.90 62.30 61.10 52.80 68.60 49.70 68.10 57.70 79.30Pr 5.04 6.05 7.16 N.D# 7.33 7.50 6.26 9.99 5.88 7.85 7.15 9.15Nd 18.20 22.80 27.70 N.D# 27.50 28.30 23.70 37.30 23.50 29.20 27.30 34.70Sm 3.53 4.68 5.88 N.D# 5.49 5.77 5.07 7.16 5.14 6.03 5.79 6.91Eu 0.95 1.35 1.69 N.D# 1.25 1.28 1.50 1.84 1.45 1.59 1.30 1.54Gd 3.60 4.46 6.10 N.D# 5.36 5.84 5.07 6.73 4.78 5.68 5.34 6.39Tb 0.56 0.67 0.84 N.D# 0.76 0.85 0.78 0.91 0.68 0.82 0.81 0.94Dy 3.19 3.91 5.05 N.D# 4.58 5.03 4.54 4.94 3.96 4.87 4.42 5.12Ho 0.65 0.71 0.98 N.D# 0.90 1.00 0.84 0.98 0.79 0.95 0.88 0.96Er 2.10 2.15 2.88 N.D# 2.70 2.92 2.49 2.76 2.12 2.73 2.55 2.88Tm 0.32 0.29 0.39 N.D# 0.37 0.42 0.34 0.38 0.31 0.40 0.35 0.42Yb 2.11 1.88 2.58 N.D# 2.52 2.83 2.11 2.48 1.92 2.61 2.34 2.61Lu 0.33 0.30 0.38 N.D# 0.37 0.41 0.32 0.37 0.30 0.38 0.35 0.40Mg# 52.62 51.40 48.86 38.87 56.20 57.07 40.06 48.23 64.35 60.69 74.60 50.1787Sr/86Sr N.D# N.D# 0.7072 N.D# 0.7064 0.7071 N.D# N.D# N.D# N.D# N.D# N.D#

143Nd/144Nd N.D# N.D# 0.5125 N.D# 0.5125 0.5124 N.D# N.D# N.D# N.D# N.D# N.D#

87Rb/86Sr N.D# N.D# 0.7890 N.D# 0.1510 0.6310 N.D# N.D# N.D# N.D# N.D# N.D#

147Sm/144Nd N.D# N.D# 0.1283 N.D# 0.1207 0.1233 N.D# N.D# N.D# N.D# N.D# N.D#

(87Sr/86Sr)i N.D# N.D# 0.7067 N.D# 0.7063 0.7067 N.D# N.D# N.D# N.D# N.D# N.D#

(143Nd/144Nd)i N.D# N.D# 0.5124 N.D# 0.5124 0.5124 N.D# N.D# N.D# N.D# N.D# N.D#

eNd(T) N.D# N.D# �3.04 N.D# �3.33 �4.07 N.D# N.D# N.D# N.D# N.D# N.D#

Qmz: Quartz monzonite, Gd: Granodiorite, Gr: Granite, Md: Monzodiorite, Mz: Monzonite, Mgb: Monzogabbro, Gb: Gabbro, Di:Diorite.N.D#: Not determinated.

142 A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148

(Eu/Eu* = 0.58–0.89). All of the samples exhibit similar trace ele-ment abundance patterns, with enrichment in large ion lithophile(LIL) elements and negative anomalies in high field strength (HFS)elements compared to primitive mantle (Sun and McDonough,1989; Fig. 4B). Strongly pronounced negative Ba, Nb, Ta, Sr, P,and Ti anomalies are present in the felsic rocks, as well as negativeBa, Nb, Ti and, to a lesser extent, Ta anomalies are observed amongthe intermediate to mafic rocks. The intermediate to mafic rocksshow slight depletions in P, Sr, and Ti, although some samples dis-play minor enrichments in P and Sr.

5.2. Sr–Nd isotopes

Four felsic and three intermediate-mafic rock samples wereselected for determination of 143Nd/144Nd and 87Sr/86Sr ratios. TheRb–Sr and Sm–Nd data for representative samples are provided inTable 1. 87Sr/86Sr and 143Nd/144Nd initial ratios were correctedaccording to the 47 Ma age of the Kuh-e Dom intrusion (Hassan-zadeh, 2011, personal communication) obtained via zircon U–Pbgeochronology. The initial 87Sr/86Sr ratios for the felsic unit rangefrom 0.7067 to 0.7069, and those of the intermediate to mafic unitvary from 0.7063 to 0.7067. The initial Nd isotope values of theintrusion range from 0.51228 to 0.512342 for the felsic unit and0.51238 to 0.51243 for the intermediate to mafic unit. All the sam-ples are displaced under the extension of the mantle array on the Ndversus Sr isotope covariation diagram (Fig. 5) and exhibit a negative

correlation between initial 143Nd/144Nd values and initial 87Sr/86Sr(47 Ma) ratios. This correlation is generally attributed to interactionbetween mantle-derived and crust or crustally derived magmas(Rollinson, 1993). Comparison of the Natanz (Haschke et al., 2010)and Kal-e-Kafi (Ahmadian et al., 2009) intrusions with the nearbyKuh-e Dom intrusion, indicate consistently low initial Sr isotoperatios and high initial Nd isotope ratios, as suggested by theobservation that their 143Nd/144Nd(t) vs. 87Sr/86Sr(t) values plot nearto the lithospheric mantle-melting trajectory (Rollinson, 1993).

6. Discussion

6.1. Magma interaction process

Three petrogenetic scenarios are possible in magmatic systems:(1) closed-system fractional crystallization, (2) assimilation–frac-tional crystallization (AFC), and (3) magma mixing.

The geochemical data for the Duh-e Dom intrusion suggest thatthe rocks are partly fractionated I-type granites with characteristicnegative Ba, Nb, Sr, P, Eu, and Ti anomalies. Sr and P show a morecomplicated behavior and are relatively enriched in the intermedi-ate-mafic rocks and depleted in the more evolved ones (Fig. 4B).Negative Nb–Ti anomalies are thought to be related to the fraction-ation of Ti-bearing phases (titanite, etc.). Moreover, negative Nb,Ta, and Ti anomalies are the typical features of arc crust and or

Fig. 3. (A) Plot of total alkalis against silica (after Middlemost, 1994). (B) I-type metaluminous granitoid samples identified on the Al2O3/CaO + Na2O + K2O molecular ratio vs.Zr + Nb + Ce + Y (Condie et al., 1999), (C) K2O vs. SiO2 diagrams indicating represented magma type for the studied, after Rickwood (1989).

Fig. 4. (A) Chondrite-normalized REE patterns for the studied samples (values fromSun and McDonough, 1989). (B) Primitive mantle-normalized, trace elementabundance diagram (spider diagrams) for representative samples. Normalizationfactors are from Sun and McDonough (1989).

Fig. 5. 143Nd/144Nd(t) values vs. initial Sr isotopic ratios indicating the source forthe magma from the Kuh-e Dom.

A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148 143

crustal contamination, while the negative P anomalies shouldresult from apatite fractionation. The Kuh-e Dom granitoids arecharacterized by negative Ba, Sr, and Eu anomalies. This can beexplained as a result of the early crystallization of plagioclase fromthe melt or retention of these elements in feldspars at the sourceduring partial melting (Rollinson, 1993).

The Kuh-e Dom samples display moderate concave upward REEpatterns and relative depletion of middle REEs with respect toHREEs (Fig. 4A), which can be attributed to the fractionation ofhornblende and/or titanite (e.g. Romick et al., 1992; Hoskin et al.,2000). Therefore, the fractionation of plagioclase, K-feldspar, andamphibole played an important role in controlling the chemistryof the Kuh-e Dom granitoids.

144 A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148

The studied intrusion is characterized by wide variation in Zr/Nb, Zr/Y, and Y/Nb ratios. Because these elements are highlyincompatible with respect to the fractionated mineral phases, ithas been argued that their ratios should not vary significantly dur-ing a closed-system fractional crystallization. Therefore, crustalcontamination is invoked to account for the variation of theseratios (Davidson et al., 1988; Wilson et al., 1997).

Chemical compositions, as well as petrographic data(Sarjoughian et al., 2012) provide evidence for magma mixing inthe Kuh-e Dom intrusion. Both Pb and Ce are highly incompatibleelements with similar partition coefficients during low-pressurecrystallization (Pearce and Parkinson, 1993). Thus, variable Pb/Cecontents in the Pb–Pb/Ce diagram (Miskovic and Francis, 2006)can be attributed to magma mixing (Fig. 6A). Similarly, the lineartrend of the intermediate-mafic samples presented on the Ti/Zrvs. Yb/Hf diagram (Fig. 6B) is expected for the mixing betweenmafic and felsic magmas (Aydogan et al., 2008).

Fig. 6C depicts a linear relationship between 87Sr/86Sr and1/MgO, which indicates that this intrusion was derived from a mix-ture of two magmas (Faure, 1986). These features, in conjunctionwith other geochemical data, are consistent with magma mixingprocesses, as suggested by previous studies (Sarjoughian et al.,2012).

In general, magma mixing has been widely recognized from thewhole rock geochemistry and Nd and Sr isotopic data for the Kuh-eDom intrusion. Interactions between two magmas occur in magmachambers, where fractional crystallization can take place before

Fig. 6. (A) Trend of fractional crystallization (FC), assimilation along with fractional c(Miskovic and Francis, 2006). (B) Plots of Ti/Zr vs. Yb/Hf for the studied intrusion. (C) The

the magmas reach in the near to surface. These processes can mod-ify the major, trace element and isotopic compositions of themagmas.

6.2. Magma genesis

Three distinct petrogenetic models for magma genesis are dis-cussed to explain the petrological and geochemical features ofI-type intrusive rocks: (i) fractionation of mantle-derived magma,(ii) reaction of mantle-derived magma with crustal rocks, and(iii) partial melting of crust (Wilson, 1989). It has been suggestedthat primary magmas generated by equilibrium partial melting ofmantle peridotite should have high Mg#, Ni and Cr concentrationsand low Al2O3 content. Hence, the low Mg#, Ni and Cr contents andthe high Al2O3 contents of the Kuh-e Dom samples are not consis-tent with the idea that the basic parental melt was in equilibriumwith the mantle source. Additionally, the Kuh-e Dom Nd–Sr isoto-pic signatures (eNd(T) = �5.89 to �3.04; initial 87Sr/86Sr = 0.7063–0.7069) show that they were not formed directly from depletedmantle-derived magmas. The intrusive rocks are characterized byLILE enrichment relative to the HFSE. This could be related to crus-tal contamination (Hildreth and Moorbath, 1988), or it mightreflect mantle enrichment events prior to melting, as proposedby Rottura et al. (1998).

It has been shown that certain trace elemental ratios, such asNb/La and Zr/Nb, can be very useful in identifying source regions,even in the case of felsic magmas. Thieblemont and Tegyey

rystallization (AFC) and magma mixing (Mix) processes in the Pb–Pb/Ce diagramincreasing 87Sr/86Sr vs. 1/MgO, indicating derivation from a mixture of two magmas.

Fig. 7. A simple modeling diagram showing a trend of 143Nd/144Nd(t) vs. (87Sr/86Sr)i

isotope variation of the Kuh-e Dom intrusive rocks. LCC: lower continental crust.UCC: upper continental crust.

A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148 145

(1994) used Nb and Zr to study the influence of the continentalcrust on magmatic rocks, considering that Zr/Nb ratio in continen-tal rocks is about 22–25 and in the enriched mantle-type reservoiris about 6.3–7.6 (Morata et al., 2005). The average Zr/Nb ratios forthe Kuh-e Dom felsic samples and for the intermediate-mafic sam-ples are 11.16 and 9.4, respectively. These values fall betweenthose of the crust and mantle compositions. In addition, the pri-mordial mantle is characterized by a moderate Nb/La ratio of1.01 (McDonough et al., 1992) and ancient continental crust hasa Nb/La of 0.46 (Weaver and Tarney, 1984). The average Nb/Laratios of Kuh-e Dom felsic samples and intermediate-mafic rocksare 0.48 and 0.61 respectively. The felsic rocks contain higher pro-portions of crustal material than the intermediate-mafic rocks,which could display the mixing of the crust-enriched mantle invarious proportions, as already pointed out in the previous studies(Sarjoughian et al., 2012).

The spidergrams of the Kuh-e Dom intrusion are similar andcharacteristically display negative anomalies of Nb, Ba, Sr, Ti, andTa. These anomalies could result either from the low content ofthese elements in the source, or their retention in the residue dur-ing partial melting (Tagne-Kamga, 2003). The moderate fraction-ated REE patterns and slightly enriched Y patterns of thechondrite-normalized diagrams generally observed in the studiedsamples indicate an amphibole-bearing, garnet-free source. Thenegative Nb and Ti anomalies can also be explained by the pres-ence of hornblende in the source (Farahat et al., 2007). The unfrac-tionated HREE (and Y) patterns suggest that the magmas wereproduced outside the garnet stability field, whereas the negativeEu and Sr anomalies could indicate that plagioclase was stable inthe source. All these features are consistent with low pressures(<0.8 Gpa) magma generation (Arth, 1979; Barker, 1979; Mark,1999).

Roberts and Clemens (1993) postulated that most high-potassium, calc-alkaline, I-type granitoid magmas could be generatedthrough partial melting of older meta-igneous rocks in the lowercrust. These granitic to tonalitic melts are result from thermalextremes in their lower crustal environments. Granitoids withhigh-K calc-alkaline affinity are characterized by enrichment ofLILEs (e.g., Cs, K, Rb, U, and Th) relative to HFSEs (especially Nband Ti). Experimental data presented by Rapp and Watson (1995)on partial melting of basaltic rocks suggest that the granitic tointermediate melts (tonalitic, quartz dioritic, and dioritic composi-tions) may be produced at 8–32 kbars and 1000–1100 �C. Stillhigher degrees of melting (40–60%) result in more mafic melts(gabbro–diorite). But the high Mg and Na2O contents of someKuh-e Dom gabbro–diorites can be totally ruled out, which is inconflict with partial melting of lower crust. They have resultedfrom the interaction between crustal-derived melts and the uppermantle. Mantle-derived mafic magmas injection into the crust hasbeen widely considered to be an important mechanism in generat-ing silicic melts in the continental crust (Huppert and Sparks,1988; Atherton and Petford, 1993; Petford and Gallagher, 2001)and mantle-derived mafic magmas can act either as a parentalsource or as the thermal trigger for crustal melting (Grunder,1995).

In order to estimate the proportion of mantle–crust component,a simple mixing model was employed using a Microsoft Excelspreadsheet program (Ersoy and Helvaci, 2010). The underlyingassumption of this model is that: parental magma derived from adepleted-mantle source mixed with crustal material as two-end-members (Karsli et al., 2010). However, depleted mantle compo-nents are unlikely to occur in a subduction-related tectonic setting,because fluids released from the dehydrating subducting slab in avolcanic arc setting metasomatize the overlying mantle wedge andleads to the formation of enriched mantle. Therefore it can beassumed that the mafic end member was derived from relatively

enriched mantle like the Natanz gabbro (Haschke et al., 2010).The Sr–Nd isotopic ratios explaining the modeling results are givenin Fig. 7. Projection of the mixing lines suggests an origin for thefelsic and intermediate-mafic magma in Kuh-e Dom involving amagma mixing process. Based on the proportions of the incorpo-rated end members, the modeling results demonstrated that56–74% lower crust-derived magma may be incorporated withthe 26–44% enriched mantle-derived mafic melt to generate thefelsic rocks. In contrast, 66–84% enriched mantle-derived maficmagma incorporates 16–34% lower crust-derived magma to pro-duce the intermediate-mafic rocks. However, in general it seemsthat upper crustal components (UCC) played a minor role in thegeneration of the studied samples, whereas enriched mantle-derived basaltic magma and the lower crust (LCC) had an impor-tant role in formation of the studied magma.

The felsic rocks were likely generated by the partial melting ofmafic crustal protoliths heated and mixed to low degrees with con-temporaneous mantle-derived basaltic magmas. The intermediate-mafic rocks were also produced by interaction between mantle andcrustal magmas, but in comparison has a greater proportion ofmantle-derived magma. Therefore, the mantle-derived maficmagma intruded into the lower continental crust, providing thenecessary heat and material resources for dehydration melting ofthe lower crust to generate the whole spectrum of magmacompositions.

6.3. Tectonic setting

The studied rocks are similar to amphibole-rich calc-alkalinegranitoids (ACG) formed in an active continental margin(Barbarin, 1999). The selective enrichment of LILEs and LREEs rel-ative to the HFSEs and HREE display close similarities to those ofthe magmatic arc granites (Pearce et al., 1984).

The low TiO2 contents (0.37–1.07%) and variable Al2O3 contents(14.95–17.74 wt.%) are typical of subduction-related potassic igne-ous rocks (Peterson et al., 2002). All the samples have a high Y con-tent (>16 ppm), similar to the average volcanic arc magmas, whichgenerally contain more than 15 ppm yttrium (Cluzel et al., 2005).The low Hf/Sm ratios (avg. 0.95) (Lafleche et al., 1991) and highBa/La (avg. 16.92) and Ba/Zr ratios (avg. 2.98) (Ajaji et al., 1998)are also indicative of subduction-related orogenic magmatism.

As shown in Fig. 8A and B, the Kuh-e Dom pluton has certaintrace-element geochemical features similar to those of volcanicarc granites (VAG; Pearce et al., 1984). Moreover, like most activecontinental margin granites, the plutonic rocks are characterized

Fig. 8. (A and B) Tectonic discrimination diagrams of Pearce et al. (1984). Fields for Syn-COLG (Syncollisional), VAG (Volcanic arc), WPG (Within-plate) and ORG (Ocean-ridge)granites are indicated.

146 A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148

by very high Ba concentrations and high Ba/Nb ratios (>28, Fittonet al., 1988). Results obtained are consistent with previous reportson the igneous rocks of the UDMA (e.g., Berberian and King, 1981;Shahabpour, 2007). Recent tectono-magmatic syntheses have sug-gested that the Eocene magmatic event may have been a conse-quence of complex processes involving the subduction of theNeo-Tethys oceanic crust beneath the Iranian microcontinent.

7. Comparison with other Intrusions in the UDMA

Geochemical and isotopic data on the Kuh-e Dom intrusiverocks were compared with those available for adjacent graniticrocks in the UDMA, such as the Natanz (Haschke et al., 2010) andKal-e-Kafi intrusions (Ahmadian, 2012; Ahmadian et al., 2009).Strontium contents of the Eocene arc rocks in the Natanz intrusionand all granitoid rocks of the Kal-e-Kafi intrusion tend to havehigher Sr and lower Y concentrations than the Miocene arc rocksin the Natanz and all granitic rocks of the Kuh-e Dom intrusion(Table 2). High Y concentrations in granitoid rocks of the Kuh-e

Table 2Sr and Y values and Sr/Y ratios from the Kal-e-Kafi and Natanz intrusions.

Sample Natanz sample Kal-e-Kafi

Age Sr Y Sr/Y Sr Y Sr/Y

M85 Miocene 409 22 18.59 K75 1530 11 139.09M87 Miocene 455 23 19.78 K77 1880 15 125.33M144 Miocene 381 31 12.29 K152 1320 15 88.00M152 Miocene 387 29 13.34 K190 1640 20 82.00M62 Miocene 284 30 9.47 K24 1230 16 76.88M36 Miocene 274 25 10.96 K60 1630 17 95.88M53 Miocene 267 27 9.89 K75 1907 13 146.69M201 Miocene 273 30 9.10 K18 1130 23 49.13M109 Miocene 252 26 9.69 K112 3063 6 510.50M226 Miocene 236 29 8.14 K112 1334 9 148.22M224 Miocene 232 24 9.67 K39 1300 15 86.67M134 Miocene 226 26 8.69 K50 1360 14 97.14M166 Miocene 178 22 8.09 K162 1200 14 85.71M205 Miocene 141 14 10.07 K61 1494 20 74.70M164 Miocene 135 17 7.94 K98 1029 18 57.17E5173 Eocene 800 13 61.54 K62 1530 16 95.63ER5 Eocene 849 15 56.60 K66 1290 19 67.89ER7 Eocene 901 14 64.36 K124 1450 24 60.42ER9 Eocene 741 12 61.75 K1 1040 14 74.29ER10 Eocene 809 12 67.42 K23 1510 19 79.47ER1 Eocene 951 12 79.25 K25 1030 11 93.64ER6 Eocene 569 8 71.13ER3 Eocene 537 7 76.71ER2 Eocene 521 8 65.13E4490 Eocene 627 10 62.70

Dom and Miocene rocks of the Natanz intrusions point to a gar-net-free source, whereas the low Y contents in the Kal-e-Kafi intru-sion and Eocene rocks of the Natanz intrusion suggest that theincorporated source material had a garnet-bearing restite. Hence,higher Sr/Y of the Kal-e-Kafi intrusion and Eocene rocks of theNatanz intrusion than the Kuh-e Dom intrusion and Miocene rocksof the Natanz intrusion can be best explained by their differentmelt sources.

The Natanz and Kal-e-Kafi intrusions have a tendency to showrelatively lower values of 87Sr/86Sr(i) and higher ratio of143Nd/144Nd(i) than those from the Kuh-e Dom intrusion. TheNatanz and Kal-e-Kafi intrusions are compositionally similar tothose derived from partial melting of a subduction-related metaso-matizes lithospheric mantle source affected by various degrees ofcrustal contamination and differentiation during ascent throughcrust. The Nd–Sr isotopic compositions indicate a hybrid originfor the Kuh-e Dom intrusion so that its composition can beexplained as a result of interaction between mantle-derived meltand lower continental crust. However, the felsic rocks have signif-icantly higher initial 87Sr/86Sr and lower 143Nd/144Nd values thanintermediate-mafic rocks, indicating a dominant crustal compo-nent in the melt which generated the felsic rocks.

As previously mentioned, different parts of this intrusion, likeother igneous rocks found in the UDMA, have a geochemical signa-ture indicating formation in a volcanic arc setting in the northernmargin of the Neo-Tethys, as an active continental margin. How-ever, Ahmadian et al. (2009) suggested that high Sr contents(1500–2000 ppm) of the mafic Kal-e-Kafi end members indicate ahigh-Sr melt source, i.e., the mantle or lower crust and very highSr/Y ratios (Sr/Y > 140), indicate metasomatism and eclogitic resid-ual and/or source mineralogies (Haschke and Ben-Avraham, 2005);this could be a result of arc-root delamination of the lower mostpart of the lithospheric mantle (Ahmadian, 2012; Ahmadianet al., in preparation).

Haschke et al. (2010) believed that the Eocene and MioceneNatanz arc melts cannot have equilibrated with the same residualmineralogy. The change in melt residual mineralogy and composi-tion was caused by collision-related thickening and deepening ofthe Natanz lower arc crust. Foundering of the dense, unstablearc-root into the mantle through delamination caused thereplacement of eclogite by buoyant and hot mantle. Therefore,delamination and subsequent melting of enriched lithosphericgarnet-bearing peridotite is considered the cause for the EoceneNatanz magmatism. Post delamination Miocene magmatism inthe Natanz arc segment continued mainly as melts from relativelyradiogenic Sr isotope lithospheric peridotite with lower Srcontents, higher Yb and Y contents. However, the main difference

Fig. 9. Evolution stages for the generation of the Kuh-e Dom magma.

A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148 147

is that post delamination melts show a clear mantle lithosphericgeochemical signature and no longer equilibrated with a garnet-bearing arc crustal keel.

Although it proposed that the Kal-e-Kafi and Eocene Natanzintrusions were generated during delamination of the lithosphericmantle, presented geochemical data of the Kuh-e Dom intrusiondemonstrate some differences with those two adjacent plutons.Also there are some differences between the isotopic characteris-tics of the Miocene Natanz and Kuh-e Dom intrusions that can beattributed to higher contamination of Kuh-e Dom intrusion withlower crust.

8. Magma formation

Based on the ample evidence presented in previous sections, theKuh-e Dom intrusion has been produced by crystallization andmixing of magmas from different sources. The felsic magma wasgenerated during the melting of the mafic lower crustal material.Injection of fractionated mantle-derived mafic magmas into thebase of the lower crust, produced mixing of mafic and felsic magmato yield the gabbro to granitic magmas of the Kuh-e Dom intrusion.

The Kuh-e Dom original magma evolved in two stages (Fig. 9).(1) The first stage started at the crust–mantle boundary (�40 kmdepth; Dehghani and Makris, 1983). The fractioned mantle-derivedbasic melts caused the partial melting of the lower crust and mixedwith the acidic resultant melts, forming intermediate-mafichybridized magma. (2) In the second stage, repeated injections ofmafic magmas into the lower crust caused local partial meltingof crustal material, forming a more acidic magma. After the mixingof the original magmas in the lower crust, newly formed magmasascended to shallow depths, producing this magmatic systemthrough assimilation-fractionational crystallization processes.

9. Conclusions

The following conclusions can be drawn from the geochemical,petrological, and tectonic data discussed above:

1. The upper Eocene Kuh-e Dom plutonic rocks display a widecompositional range from gabbro to granite. The emplacementof the pluton, which has metaluminous I-type characteristicscommonly attributed to the calc-alkaline series, took place at�47 Ma.

2. All the geochemical characteristics, in conjunction with the iso-topic ratios, indicate the formation of the rocks by interactionprocesses between lower crust-derived felsic and mantle-derived mafic melts. According to the geochemical features ofthe Kuh-e Dom intrusion, it can be deduced that the sourcesinvolved in the genesis of these granitoids were a mantle sourceand lower crust carrying a subduction-related geochemical

signature. The mafic magmas were most likely derived fromthe upper mantle, and they transferred both heat and materialto the lower crust, producing granitic magmas through partialmelting.

3. Enriched in LILE and LREE relative to the HFSE and HREE withnegative Ba, Nb, Ti, Ta, P, Sr and Eu anomalies in the REE andprimitive mantle-normalized multi-element patterns andtectono magmatic discrimination diagrams, suggest that theKuh-e Dom intrusion was formed in a continental arcmagmatism.

4. This suggestion is consistent with the interpretation of the Uru-mieh–Dokhtar Magmatic Arc as an active continental marginduring subduction of the Neotethys oceanic crust beneath theCentral Iranian microcontinent.

Acknowledgements

This study is a synthesis of the Ph.D. thesis by F. Sarjoughian.Thanks to the University of Tehran for supporting this projectunder grants provided by the research council. Partial funding forthis project was provided by the Research Office at the Universityof Payame Noor; we wish to acknowledge the generous supportfrom all staff of that office. We acknowledge Prof. Bor-ming Jahn,Prof. David Lentz, Prof. Louie, and anonymous reviewers for theirconstructive comments leading to important improvements inthe manuscript.

References

Agard, P., Omrani, J., Jolivet, L., Mouthereau, F., 2005. Convergence history acrossZagros (Iran): constraints from collisional and earlier deformation. Int. J. EarthSci. 94, 401–419.

Ahmad, T., Posht Kuhi, M., 1993. Geochemisty and Petrogenesis of Urumiah–Dokhtar Volcanics around Nain and Rafsanjan Areas: A Preliminary Study,Treatise on the Geology of Iran. Iranian Ministry of Mines and Metals, p. 90.

Ahmadian, J., 2012. Geochemistry, Mineral Chemistry and Petrology of Kal-e KafiOre-Bearing Intrusive Bodies, E Anarak, Ph.D. Thesis, Tehran, Tarbiat-ModaressUniversity, p. 384.

Ahmadian, J., Haschke, M., McDonald, I., Regelous, M., Ghorbani, M., Emami, M.,Murata, M., 2009. High magmatic flux during Alpine–Himalayan collision:constraints from the Kal-e-Kafi complex, central Iran. Geol. Soc. Am. Bull. 121,857–868.

Ahmadian, J., Sarjougian, F., Esna-Ashari, A., Omrani, J., Murata, M., Ozava, H., inpreparation. Geochemical characteristics of K-rich adakitic Kal-e Kafi complex(central Iran): implication for partial melting and delamination of thickenedlower crust.

Ajaji, T., Weis, D., Giret, A., Bouabdellah, M., 1998. Coeval potassic and sodic calc-alkaline series in the post-collisional Hercynian Tanncherfi intrusive complex,northeastern Morocco: geochemical, isotopic and geochronological evidence.Lithos 45, 371–393.

Alavi, M., 1994. Tectonic of the Zagros orogenic belt of Iran: new data andinterpretations. Tectonophysics 229, 211–238.

Allen, M.B., 2009. Discussion on the Eocene bimodal Piranshahr massif of theSanandaj–Sirjan zone, west Iran: a marker of the end of collision in the Zagrosorogen. J. Geol. Soc. Lond. 166, 981–982.

Allen, M.B., Armstrong, H.A., 2008. Arabia–Eurasia collision and the forcing of mid-Cenozoic global cooling. Palaeogeogr., Palaeoclimatol., Palaeoecol. 265, 52–58.

Arth, J.G., 1979. Some trace elements in trondhjemites – their implications tomagma genesis and paleotectonic setting. In: Barker, F. (Eds.) TrondhjemitesDacites and Related Rocks. Amsterdam, Developments in Petrology, vol. 6, pp.123–132.

Atherton, M.P., Petford, N., 1993. Generation of sodium-rich magmas from newlyunderplated basaltic crust. Nature 362, 144–146.

Aydogan, M.S., Coban, H., Bozcu, M., Akinci, O., 2008. Geochemical and mantle-likeisotopic (Nd, Sr) composition of the Baklan Granite from the Muratdagi Region(Banaz, Usak), western Turkey: implications for input of juvenile magmas in thesource domains of western Anatolia Eocene–Miocene granites. J. Asian Earth Sci.33, 155–176.

Barbarin, B., 1999. A review of the relationship between granitoid types, theirorigins and their geodynamic environments. Lithos 46, 605–626.

Barker, F., 1979. Trondhjemite: definition, environment and hypotheses of origin.In: Barker, F. (Eds.) Trondhjemites, Dacites and Related Rocks. Amsterdam,Developments in Petrology, vol. 6, pp. 1–11.

Berberian, M., King, G.C.P., 1981. Towards a paleogeography and tectonic evolutionof Iran. Can. J. Earth Sci. 18, 210–265.

148 A. Kananian et al. / Journal of Asian Earth Sciences 90 (2014) 137–148

Cluzel, D., Bosch, D., Paquette, J.-L., Lemennicer, Y., Montjoie, P., Menot, R.-P., 2005.Late Oligocene post-obduction granitoids of New Caledonia: a case forreactivated subduction and slab break-off. Island Arc 14, 254–271.

Condie, K.C., Latysh, N., Schmus, W.R.V., Kozuch, M., Selverstone, J., 1999.Geochemistry, Nd and Sr isotopes, and U/Pb zircon ages of Granitoid andMetasedimentary xenoliths from the Navajo volcanic field, four corners area,Southwestern United States. Chem. Geol. 156, 95–133.

Davidson, J.P., Duncan, M.A., Ferguson, K.M., Colucci, M.T., 1988. Crust-magmainteractions and the evolution of arc magmas: the San Pedro Pellardo Volcaniccomplex, southern Chilean Andes. Geology 15, 443–446.

Davoudzadeh, M., Schmidt, K., 1984. A review of the Mesozoic paleogeography andpaleotectonic evolution of Iran. Neues Jahrb. Geolo. Paläontol., Abhandlungen168, 182–207.

Dehghani, G.A., Makris, J., 1983. The gravity field and crustal structure of Iran. NeuesJahruch Geol. Palaeontol. Abhandlugen 168, 215–229.

Ersoy, Y., Helvaci, C., 2010. FC–AFC–FCA and mixing modeler: a Microsoft Excelspreadsheet program for modeling geochemical differentiation of magma bycrystal fractionation, crustal assimilation and mixing. Comput. Geosci. 36, 383–390.

Falcon, N., 1974. Zagros Mountains, Mesozoic–Cenozoic orogenic belts. In: Spencer,A. (Ed.), Special Publication of Geological Society, London, vol. 4, pp. 199–211.

Farahat, E.S., Mohamed, H.A., Ahmed, A.F., Mahallawi, M.M.E., 2007. Origin of I- andA-type granitoids from the Eastern Desert of Egypt: implications for crustalgrowth in the northern Arabian–Nubian Shield. J. Afr. Earth Sci. 49, 43–58.

Faure, G., 1986. Principle of Isotope Geology, second ed. John Wiley and Sons, NewYork, p. 589.

Fitton, J.G., James, D., Kempton, P.D., Ormerod, D.S., Leeman, W.P., 1988. The role oflithospheric mantle in the generation of Late Cenozoic basic magmas in theWestern United States. J. Petrol. 1, 331–349.

Ghasemi, A., Talbot, C.J., 2006. A new scenario for the Sanandaj–Sirjan zone (Iran). J.Asian Earth Sci. 26, 683–693.

Grunder, A.L., 1995. Material and thermal roles of basalt in crustal magmatism: casestudy from eastern Nevada. Geology 23, 952–956.

Haghipour, A., Aghanabati, A., 1985. Geological Map of Iran: Iran, Geological Surveyof Iran, Scale 1:2,500,000 Sheet.

Haschke, M., Ben-Avraham, Z., 2005. Adakites from collision-modified lithosphere.Geophys. Res. Lett. 32, L15302.

Haschke, M., Ahmadian, J., Murata, M., McDonald, I., 2010. Copper mineralizationprevented by arc-root delamination during Alpine–Himalayan collision inCentral Iran. Econ. Geol. 105, 855–865.

Hildreth, W., Moorbath, S., 1988. Crustal contribution to arc magmatism in theAndes of southern Chile. Contrib. Mineral. Petrol. 98, 455–489.

Hoskin, P.W.O., Kinny, P.D., Wyborn, D., Chappell, B.W., 2000. Identifying accessorymineral saturation during differentiation in granitoid magmas: an integratedapproach. J. Petrol. 41, 1365–1395.

Huppert, H.E., Sparks, R.S.J., 1988. The generation of granitic magma by intrusion ofbasalt into continental crust. J. Petrol. 29, 599–624.

Jung, D., Kursten, M., Tarkian, M., 1976. Post-mesozoic volcanism in Iran and itsrelation to the subduction of the Afro–Arabian under the Eurasian plate. In:Pilger, A., Rosler, A. (Eds.), Afar between Continental and Oceanic Rifting.Schweizerbartsche Verlagbuchhandlung, Stuttgart, Germany, pp. 175–181.

Karsli, O., Dokuz, A., Uysal, I., Aydin, F., Chen, B., Kandemir, R., Wijbrans, J., 2010.Relative contributions of crust and mantle to generation of Campanian high-Kcalc-alkaline I-type granitoids in a subduction setting, with special reference tothe Harsit Pluton, Eastern Turkey. Contrib. Mineral. Petrol. 160, 467–487.

Lafleche, M.R., Dupuy, C., Dostal, J., 1991. Archaean orogenic ultrapotassicmagmatism: an example from the Southern Abitibi greenstone belt.Precambrian Res. 52, 71–96.

Mark, G., 1999. Petrogenesis of mesoproterozoic K-rich granitoids, southern Mt.Angelay igneous complex, Cloncury district, northwestern Queensland. Aust. J.Earth Sci. 46, 933–949.

McDonough, W.F., Sun, S.-S., Ringwood, A.E., Jagoutz, E., Hofmann, A.W., 1992. K, Rband Cs in the earth and moon and the evolution of the earth’s mantle. Geochim.Cosmochim. Acta 56, 1001–1012.

McQuarrie, N., Stock, J.M., Verdel, C., Wernicke, B.P., 2003. Cenozoic evolution ofNeotethys and implications for the causes of plate motions. Geophys. Res. Lett.30 (30), 2036. http://dx.doi.org/10.1029/2003GL017992.

Middlemost, E.A.K., 1994. Naming materials in the magma/igneous rock system.Earth Sci. Rev. 37, 215–224.

Miskovic, A., Francis, D., 2006. Interaction between mantle-derived and crustal calc-alkaline magmas in the petrogenesis of the Paleocene Sifton Range volcaniccomplex, Yukon, Canada. Lithos 87, 104–134.

Mohajjel, M., Fergusson, C.L., Sahandi, M.R., 2003. Cretaceous–tertiary convergenceand continental collision Sanandaj–Sirjan zone Western Iran. J. Asian Earth Sci.21, 397–412.

Morata, D., Oliva, C., de la Cruz, R., Suarez, M., 2005. The Bandurrias Gabbro; lateOligocene alkaline magmatism in the Patagonian Cordillera. J. South Am. EarthSci. 18, 147–162.

Morley, C.K., Kongwung, B., Julapour, A.A., Abdolghafourian, M., Hajian, M., Waples,D., Warren, J., Otterdoom, H., Srisuriyon, K., Kazemi, H., 2009. Structuraldevelopment of a major late Cenozoic basin and transpressional belt in centralIran: the Central Basin in the Qom–Saveh area. Geosphere 5, 1–38.

Nadimi, A., 2010. Active Strike-Slip Faults in the Central Part of the Sanandaj–SirjanZone of Zagros Orogen, Iran. Ph.D. thesis, Poland, University of Warsaw, p. 121.

Pearce, J.A., Parkinson, I.J., 1993. Trace element models for mantle melting:application to volcanic arc petrogenesis. In: Prichard, H.M., Alabaster, T.,Harris, N.B., Neary, C.R. (Eds.) Magmatic Processes and Plate Tectonics. London,Geological Society, London, Special Publication, vol. 76, pp. 373–403.

Pearce, J.A., Harris, N.B.W., Tindle, A.G., 1984. Trace element discriminationdiagrams for the tectonic interpretation of granitic rocks. J. Petrol. 25, 956–983.

Peterson, T.D., Van Breemen, O., Sandeman, H., Cousens, B., 2002. Proterozoic (1.85–1.75 Ga) igneous suites of the Western Churchill Province. granitoid andultrapotassic magmatism in a reworked Archaean hinterland. Precambrian Res.119, 73–100.

Petford, N., Gallagher, K., 2001. Partial melting of mafic (amphibolitic) lower crustby periodic influx of basaltic magma. Earth Planet. Sci. Lett. 193, 483–499.

Rapp, R.P., Watson, E.B., 1995. Dehydration melting of metabasalt at 8–32 kbar:implications for continental growth and crust–mantle recycling. J. Petrol. 36,891–931.

Rickwood, P.C., 1989. Boundary lines within petrologic diagrams which use oxidesof major and minor elements. Lithos 22, 247–263.

Roberts, M.P., Clemens, J.D., 1993. Origin of high-potassium, calcalkaline, I-typegranitoids. Geology 21, 825–828.

Rollinson, H.R., 1993. Using Geochemical Data: Evaluation, Presentation,Interpretation. Longman Scientific and Technical, London, p. 352.

Romick, J.D., Kay, S.M., Kay, R.M., 1992. The influence of amphibole fractionation onthe evolution of calc-alkaline andesite and dacite tehpra from the centralAleutians, Alaska. Contrib. Mineral. Petrol. 112, 101–118.

Rottura, A., Bargossi, G.M., Caggianelli, A., Del Moro, A., Visona, D., Tranne, C.A.,1998. Origin and significance of the Permian high-K calc-alkaline magmatism inthe central-eastern Southern Alps, Italy. Lithos 45, 329–348.

Sarjoughian, F., Kananian, A., Haschke, M., Ahmadian, J., Ling, W., Keqing, Z., 2012.Magma Mingling and hybridization in the Kuh-e Dom pluton, Central Iran. J. ofAsian Earth Sci. 54–55, 49–63.

Shahabpour, J., 2007. Island-arc affinity of the Central Iranian volcanic belt. J. AsianEarth Sci. 30, 652–665.

Stöcklin, J., 1968. Structural history and tectonics of Iran; a review. Am. Assoc.Petrol. Geol. Bull. 52, 1229–1258.

Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanicbasalts: implications for mantle composition and processes. In: Saunders, A.D.,Norrey, M.J. (Eds.) Magmatism in the Ocean Basins. London, Geological Society,London, Special Publication, vol. 42, pp. 313–345.

Tagne-Kamga, G., 2003. Petrogenesis of the Neoproterozoic Ngondo Plutoniccomplex (Cameroon, west central Africa): a case of late-collisional ferro-potassic magmatism. J. Afr. Earth Sci. 36, 149–171.

Technoexport, 1981. Detail Geology Prospecting in the Anarak Area Central Iran(Kuh-e Dom, Rizab-e Maryam and Chah Alikhan localities). Geological Survey ofIran, No-9.

Thieblemont, D., Tegyey, M., 1994. Une discrimination geochimique des rochesdifferenciees temoin de la diversited origine et de situation tectonique desmagmas calco-alcalins. CR Acad Sci Ser II 319, 87–94.

Weaver, B.L., Tarney, J., 1984. Empirical approach to estimating the composition ofthe continental crust. Nature 310, 575–577.

Wilson, M., 1989. Igneous Petrogenesis. Chapman and Hall, London, p. 466.Wilson, M., Tankut, A., Gulec, N., 1997. Tertiary volcanism of the Galatia Province,

NW Central Anatolia, Turkey. Lithos 42, 105–121.