Geochemistry and Petrogenesis of Granitoid

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231– 6345 (Online) An Open Access, Online International Journal Available at www.cibtech.org/sp.ed/jls/2014/04/jls.htm 2014 Vol. 4 (S4), pp. 1693-1709/Ardalan et al. Research Article GEOCHEMISTRY AND PETROGENESIS OF GRANITOID PLUTON AND ENCLAVES IN QOHROUD – KASHAN *Afshin Ashja Ardalan1, Mina Khodadadi1, Mohammad Hashem Emami2, Jamal Sheikh Zakariaie 3, Mohammad Hosein Razavi4 and Abdollah Yazdi5 1Department of Geology, Islamic Azad University, North Tehran Branch, Tehran, Iran 2Department of Geology, Islamic Azad University, Islamshahr Branch, Islamshahr, Iran 3Department of Geology, Islamic Azad University, Science and Research Branch, Tehran, Iran 4Department of Geology, Kharazmi University, Tehran, Iran 5Department of Geology, Islamic Azad University, Kahnooj Branch, Kerman, Iran *Author for Correspondence

ABSTRACT The area is located in northwest of Isfahan, 30 kilometers south of Kashan District, and southern section of Qamsar. The longitude of the area of study is 51º, 19′, 13″, E to 51º, 26′, 26″, E and its latitude is 33º, 34′, 24″ N to 33º, 44′, 24″ N. The rocks of the Qohrud batholithic mass and its enclaves are more quartz monzonite. The rocks are peraluminous that are rich of alomin. These rocks are classified in magmatic series of subalkaline, and belong to calcalkaline magmatic series subdivision. According to origin classification, they are considered I type, S- type and A- type. Tectonically are both in the position of volcanic arc granite (VAG) that is related to continental arc granite (CAG) and within plate granite (WPG) that is related to continental rifting in back arc basin. The rocks of the Qohroud area originate from continental crust arc that mixing with back arc basin rifting magmas and hybrid magma stop in the upper crust and balanced.

Keywords: Kashan, Qohroud, Granitoid, Petrogenesis

INTRODUCTION The igneous rocks of this area are themselves part of the Urumieh - Dokhtar or Sahand - Bazman volcanic belt. The area which is being studied is located in northwest of Isfahan Province, 30 kilometers south of Kashan, and south of the Qamsar county. This area is adjacent to Qaza’an, Qohroud, and Jevinan parishes (Figure 1), (Internet, 2013). This area is located at the east side of the 1:100000 geological map of Kashan, in Qohroud mountain range which is illustrated as red granitoid (Zahedi, 1991).

MATERIALS AND METHODS 1- Methodology of Research and Processes a- Arriving at the area for collecting (carrying out) the rock samples and the field observation for determining points and documenting ground checkpoints by GPS. b- Selecting a number of samples for XRF and ICP- ms analysis. c- Statistical and calculative computer works and plots and conclusion.

RESULTS AND DISCUSSION 3-Discussion 3-1- Geology of the Area The longitude of the area of study is 51º, 19′, 13″, E to 51º, 26′, 26″, E and its latitude is 33º, 34′, 24″ N to 33º, 44′, 24″ N (Figure 2). The collected samples that taken from the Qohroud pluton arequartz monzonite, granite, granodiorite, quartzmonzodiorite. But mostly is quartz monzonite. Also, number of enclaves can be seen that are generally quartz monzonite.

Figure 1: Geographical location of the area with 1:2500000 scale (Internet, 2013)

Figure 2b: Legend of Geological map of the area with 1:100000 scale (Zahedi, 1991)

3-2- Geochemistry and Petrogenesis of the Rocks of the Area Using the Chemical Analysis Data Granitoid Samples were analyzed for content of major and trace elements by XRF and ICP-MS method, (Iranian Organization for Geology and Quarry Expedition, 2012), They are presented in table (1,2,3). Also 4 enclave samples are presented similar. The granitoids are characterized by 58.6 – 70.9 % SiO2 that aregeochemically acidic and intermediate. The enclaves show a compositional range from 55.6 _ 58.9% SiO2.Also the rocks show a compositional range from 0.58 _ 1.68%LOI that are mostly less than 1. The granitoids are characterized by 1.5 – 3.1 % K2O,3.2 – 7.2 % CaO,1.9– 3% Na2O,1– 4% MgO, 2.9 – 11.5 % Fe2O3tand 13.4 – 18.1 % Al2O3. Todiscrimination different rock groups of the area and naming, using the chemical analysis data and norms, there is different diagrams are used. One of such plots is (Debon and Le-Fort, 1983) in (Figure 3). In this plot, samples are mostly positioned in adamelite (quartz monzonite) distinct. These rocks are classified in magmatic series of subalkaline, and belong to calcalkaline magmatic series (Figures 4,5,6,), (Irvine and Baragar, 1971), (Hastie et al., 2007). Also figure (6) show Co- Th plot of Classification for magmatic series, that show high- k calcalkaline and shoshonite series for Qohroud samples (Hastie et al., 2007). The rocks are peraluminous that are rich of alumin (Al2O3) (Figure 7) (Villaseca et al., 1998). According to origin classification, they are considered I- type, S- type and A- type. Some of the samples are on the border of distinct (Figure 8), (Whalen et al., 1987). Trace element compositions of granitic rocksare potentially applied for discrimination of their tectonic settings (Pearce et al., 1984; Harris et al., 1986). For the purpose of discrimination of a possible tectonic setting of the area, characterization of the granitic rocks is of particular importance. On the Y-Nb and Rb- (Y+Nb) diagrams (Figure 9), Tectonically are located both in the area of volcanic arc granite (VAG) that is continental arc granite (CAG) and within plate (WPG) that is continental rifting in back arc basin (Figure 9,10), (Harris et al., 1986). To help understand the origin and tectonic setting for these A- type granites, we show them on discrimination diagrams such as (Figure 11). The diagram use trace- element ratios to distinguish between sources for two distinct A-type compositions, A1 and A2. A1-type granitoids (Y/ Nb < 1.2) were generated in hotspots, plumes, or continental rift zones. A2-type granitoids (Y/ Nb > 1.2) are associated with post collisional settings (Eby, 1992).

Sample SiO2 Al2O3 MgO K2O TiO2 MnO Cao number Na2O M1 60.7 17.2 2.4 2 0.7 0.1 2.5 5.9 M12 63.7 16 2.1 2.5 0.6 0.2 2.2 5 M13 59.9 17.6 2.7 1.6 0.7 0.1 2.6 6.3 M16 57.9 18 2.7 1.9 0.8 0.2 2.7 6.6 M23 63.2 16.5 2.2 2.3 0.7 0.2 2.8 5 M29 58.9 17.4 2.6 1.8 0.8 0.2 3 5.8 M35 68.5 15.5 1.4 2.4 0.4 0.1 2.7 3.9 M46 55.6 17.9 3.5 1.8 0.7 0.3 3 7.2 M52 66.8 16.1 1.7 3.1 0.5 0.01 2.6 3.9 M57 65.5 16.4 2 2.8 0.5 0.01 2.7 4.2 M65 66.1 16 2.1 2.9 0.5 0.01 2.6 4.1 M71 56.9 18 3.3 2.3 0.8 0.2 2.9 6.2 M77 63.9 16.3 2.2 2.3 0.7 0.1 2.5 4.9 M84 58.6 13.4 4 2.3 1.1 0.2 1.9 5.3 M90 65.4 16 2.1 3 0.6 0.1 2.6 4.3 M97 65.6 15.8 1.9 2.3 0.6 0.1 2.5 4.6 M99 66.3 15.9 1.9 2.8 0.6 0.01 2.7 4.1 M103 62.7 16.9 2.1 1.9 0.7 0.1 2.6 5.4 M119 59 18.1 3.2 1.5 0.6 0.1 2.4 6.8 M33 70.9 15.3 1 2.7 0.3 0.01 2.8 3.2 Sample P2O5 BaO So3 LOI Fe 2O3t FeO FeOt number M1 0.2 0.01 0.01 1.16 7 4.8 5.3 M12 0.2 0.01 0.01 1.68 5.9 3.8 4.2 M13 0.2 0.01 0.01 0.83 7.2 5 5.5 M16 0.3 0.01 0.01 0.72 8 5.7 6.3 M23 0.2 0.01 0.01 0.86 5.9 3.7 4.11 M29 0.2 0.01 0.01 1.01 8.1 5.8 6.4 M35 0.2 0.01 0.01 0.62 4.1 2.2 2.4 M46 0.4 0.01 0.01 0.87 8.6 6.4 7.11 M52 0.2 0.01 0.01 0.79 3.9 1.9 2.11 M57 0.3 0.01 0.01 1.05 4.3 2.3 2.5 M65 0.2 0.01 0.01 0.89 4.3 2.3 2.5 M71 0.3 0.2 0.1 1.3 7.4 5.1 5.6 M77 0.2 0.01 0.01 0.77 5.8 3.6 4 M84 0.4 0.01 0.01 0.93 11.5 8.9 9.8 M90 0.2 0.01 0.01 0.61 4.8 2.7 3 M97 0.2 0.01 0.01 0.68 5.3 3.2 3.5 M99 0.2 0.01 0.01 0.72 4.4 2.3 2.5 M103 0.3 0.01 0.01 0.63 6.4 4.2 4.6 M119 0.3 0.01 0.01 1.25 6.6 4.5 5 M33 0.1 0.01 0.01 0.58 2.9 1.1 1.2

The characterization of these A-type samples indicates that these rocks may represent partially melted extensional crust in back arc basin that is relation to rifting. According to R1-R2 plot (Batchelor and Bowden, 1985) the rocks belong to syn-orogenic granites (Figure 12). Figure (13) show Spider plot that © Copyright 2014 | Centre for Info Bio Technology (CIBTech) 1696

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231– 6345 (Online) An Open Access, Online International Journal Available at www.cibtech.org/sp.ed/jls/2014/04/jls.htm 2014 Vol. 4 (S4), pp. 1693-1709/Ardalan et al. Research Article normalized to upper continental crust for Petrogenesis discrimination in trace element abundences. It has smooth line pattern that illustrate similar to upper continental crust (Figure 13), (Taylor and McLennan, 1995). Indeed the enclave samples also plot on the all of the diagrams and have similar pattern to other granitoid rocks of the area. According to the spider diagram the rocks of the Qohroud area originate from continental crust. The samples illustrate enrichment of U and Th and depletion of Zrand K relativeto upper continental crust. Content of U and Th trace elements show a compositional range from 2.93_ 8.1ppm U and 13.29_ 32.49 ppm Th that enriched 3 time relative to upper continental crust (table 3). At the eastern of the Qohroud pluton (around Jevinan) the amount of Uranium (U) is highest in M90 sample, but is lower than the economic limit. Geochemically the samples cluster in 3 groups and part in content of abundance of elements and for similar together (Figures 9,10,11,12, 13). Geochemically the sample analyzed data illustrate similar to Frostsdata from Yellowstone A-type granitic rocks in Wyoming in western USA (Frost et al., 1999). In western USA in the Basin and Range province, broadly distributed extensional deformation began in earliest Oligocene time, and continues today. The Sherman batholith, southeastern Wyoming, USA, shows extreme A-type petrochemical characteristics compared with other Mid- Proterozoic granite batholiths of North America (Frost et al., 1999). But Gohroud samples attribute arc characteristic compared with Yellowstone samples. It seems there is mixing between two different magma that originate from arc and back arc tectonic environment. Finally geochemical data show several groups that related to hybrid magma.

Table 2: Symbols and number of rock samples and enclaves in use for plots

Ba Ce Co Cr Cu Dy Er Eu Gd Hf

M1 323 45.03 13.59 36.31 38.92 6.06 3 0.97 4.2 9.09

M12 384 39.64 13.95 51.54 5.83 2.15 1.81 0.9 4.63 8.57

M13 284 37.37 14.69 42.11 45.04 4.65 2.96 0.8 4.93 9.82

M16 266 27.69 14.5 26.42 16.32 2.15 2.47 0.9 5.2 10.8

M23 437 41.5 13.78 34.76 7.56 6.14 2.78 0.81 4.89 8.93

M29 292 50.51 14.66 35.3 27.91 14.56 4.48 1.3 6.8 11.42

M35 719 40.33 10.21 78.96 11.1 4.61 2.43 0.83 3.27 5.25

M46 520 31.53 11.94 47.81 8.85 2.83 2.6 0.71 3.46 6.35

M52 210 76.28 13.58 92.76 75.95 11.68 4.71 1.09 6.7 10.8

M57 820 29.03 11.41 49.59 32.63 2.08 1.46 0.79 3.4 6.27

M65 890 49.54 12.05 80.74 110.28 5.01 0.72 0.96 3.46 6.98

M71 884 52.45 14.1 61.66 19.94 2.62 1.7 0.86 3.35 6.7

M77 1474 49.49 15.82 61.67 67.02 7.3 2.83 1.45 5.71 10.55

M84 572 47.23 13.04 47.86 33.44 7.34 3.14 1.13 4.94 9.18

M90 492 57.09 26.46 62.55 26.6 7.7 4.47 1.51 8.71 17.13

M97 896 68.42 16.02 59.41 23.23 4.1 2.49 1.01 4.09 7.7

M99 539 46.82 13.14 65.6 25.13 1.5 1.76 0.94 4.24 8.2

M103 889 58.99 14.34 70.66 9.06 5.74 1.28 1.05 3.55 7.06

M119 446 45.83 14.67 62.29 12.86 6.59 2.61 1.3 5.45 10.36

M33 350 42.59 16.3 67.5 21.12 0.65 2.71 1.27 4.93 10.03

Ho La Lu Nb Nd Ni Pr Cs Rb M1 0.92 15.88 0.39 28.77 10.45 10.53 7.65 6.13 46.48 M12 0.81 19.07 0.37 20.02 11.52 10.85 7.92 5.6 48.13 M13 0.93 16.17 0.42 22.08 13.15 16.25 4.94 5.34 50.16 M16 1.01 12.57 0.49 25.29 10.4 6.51 10.42 6.6 46 M23 0.95 24.65 0.37 20.21 19.2 10.31 7.33 5.98 57.78 © Copyright 2014 | Centre for Info Bio Technology (CIBTech) 1698

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231– 6345 (Online) An Open Access, Online International Journal Available at www.cibtech.org/sp.ed/jls/2014/04/jls.htm 2014 Vol. 4 (S4), pp. 1693-1709/Ardalan et al. Research Article M29 1.3 20.77 0.51 25.88 33.77 8.04 13.52 5.27 48.8 M35 0.7 26.85 0.24 18.91 13.12 13.96 3.91 3.88 67.38 M46 0.82 22.22 0.29 15.94 11.54 11.98 7.88 5.56 54.35 M52 1.35 37.14 0.49 23.14 40.21 26.76 9.63 4.7 54.95 M57 0.69 19.57 0.27 15.72 6.92 17.4 1.81 4.84 96.2 M65 0.84 33.87 0.28 17.74 15.69 18.74 6.19 4.94 119.48 M71 0.9 30.21 0.28 18.64 19.08 19.71 8.54 5.19 99.48 M77 0.98 25.21 0.46 26.05 26.11 24.89 9.08 5.85 105 M84 0.99 26.63 0.39 23.28 16.42 13.74 6.3 5.29 73.61 M90 1.52 23.84 0.74 38.07 29.27 13.78 14.54 9.82 51.59 M97 0.96 38.54 0.33 21.64 21.98 17.76 8.17 5.37 100.14 M99 0.91 30.08 0.37 22.83 9.55 10.28 4.37 5.22 65.24 M103 0.82 38.27 0.32 20.27 23.19 18.87 8.67 5.17 107.56 M119 1.01 20.78 0.47 27.86 13.05 7.98 7.54 6.05 63.46 M33 1.1 21.6 0.43 25.56 13.15 15.8 7.92 6.26 93.58

Sm Sr Ta Tb Th Tm U V M1 5.05 180 7.28 0.78 23.5 0.33 4.63 128 M12 3.59 188 6.9 0.66 14.77 0.33 4.07 113 M13 1.06 198 12.42 0.75 19.64 0.38 3.96 142 M16 3.76 182 8.12 0.89 13.29 0.4 4.77 158 M23 2.72 222 3.7 0.72 14.52 0.33 4.03 115 M29 4.88 189 17.53 0.94 18.49 0.45 4.07 167 M35 3.38 255 0.09 0.43 23.58 0.18 2.92 81.05 M46 3.29 212 0.93 0.61 13.39 0.24 4.1 75.43 M52 7.93 223 4.57 1.02 18.3 0.44 3.3 158 M57 3.39 374 0.05 0.55 18.48 0.24 4.06 78.41 M65 2.44 458 1.3 0.65 19.37 0.28 3.94 87.92 M71 3.41 386 6.61 0.6 15.99 0.25 3.81 86.54 M77 5.09 409 11.04 0.78 15.7 0.37 4.39 152 M84 5.63 286 0.09 0.79 24.33 0.34 3.94 127 M90 6.36 198 21.88 1.43 32.49 0.63 8.1 224 M97 4.87 402 6.76 0.58 22.42 0.29 4.55 103 M99 3.13 251 10.01 0.79 20.23 0.34 3.88 119 M103 3.16 416 0.09 0.52 24.09 0.29 4.01 93.77 M119 4.32 247 4.39 0.87 19.6 0.42 4.47 155 M33 3.79 362 5.47 0.87 16.52 0.41 4.67 185

Y Yb Zr Zn K Ga Ag M1 22.04 2.24 19.52 53.07 13000 23.2 0.27 M12 22.06 2.33 14.1 138 16000 27.4 0.21 M13 20.33 2.17 21.2 78.31 10000 15.37 0.14 M16 14.98 1.97 25.99 76.84 12000 21.87 0.26

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231– 6345 (Online) An Open Access, Online International Journal Available at www.cibtech.org/sp.ed/jls/2014/04/jls.htm 2014 Vol. 4 (S4), pp. 1693-1709/Ardalan et al. Research Article M23 23.54 2.55 16.49 60.64 15000 20.17 0.18 M29 51.55 5.68 32.83 85.33 12000 29.44 0.05 M35 22.78 2.52 11.41 44.86 16000 15.84 0.05 M46 19.2 1.97 10.8 43.41 12000 24.35 0.05 M52 51.23 5.1 27.55 118 20000 19.68 0.05 M57 9.64 1.02 14.67 35.28 18000 14.31 0.25 M65 11.37 1.15 10.12 31.47 19000 25.73 0.05 M71 10.98 1.15 8.65 47.57 15000 22.42 0.05 M77 21.04 2.25 20.12 65.01 15000 24.16 0.05 M84 25.46 2.68 18.39 50.66 15000 24.4 0.05 M90 42.01 4.58 18.95 76.75 20000 36.29 0.33 M97 13.99 1.53 13.36 51.88 15000 19.95 0.05 M99 18.04 2.16 19.79 43.61 18000 18.64 0.15 M103 15.52 1.48 8.01 50.85 12000 18.37 0.05 M119 26.32 3.06 23.31 57.88 10000 26.47 0.05 M33 18.38 2.23 24.65 59.01 18000 24.36 0.05

As B Be Bi Cd Ge Hg In Li M1 0.4 8.16 1.01 0.4 0.74 1.71 0.04 0.49 11.95 M12 4.98 3.9 1.02 0.4 0.8 1.63 0.04 0.71 12.55 M13 0.4 7.62 1 0.4 0.72 1.49 0.04 0.63 12.52 M16 0.4 8.84 0.9 0.52 0.79 1.91 0.04 0.61 8.34 M23 0.4 7.43 1.22 0.4 0.55 1.52 0.04 0.58 21.98 M29 0.4 7.93 2.59 0.4 0.93 1.51 0.04 0.87 44.42 M35 0.4 7.13 1.58 0.4 0.35 1.18 0.04 0.49 10.55 M46 0.4 6.75 1.14 0.4 0.34 1.43 0.05 0.49 17.45 M52 9.87 7.3 1.55 0.4 0.85 1.34 0.04 1.52 16.76 M57 7.03 7.47 1.49 0.4 0.26 1.45 0.04 0.49 10.7 M65 8.41 4.03 1.67 0.4 0.49 1.55 0.04 0.49 10.23 M71 1.88 4.57 1.75 0.4 0.37 1.46 0.04 0.49 10.47 M77 0.4 6.89 2.09 0.4 0.79 1.68 0.04 0.58 10.71 M84 5.98 2.63 1.09 0.4 0.71 1.59 0.04 0.49 7.54 M90 4.97 3.4 0.99 0.86 1.52 3.29 0.04 1.22 17.23 M97 5.6 4.32 1.62 0.4 0.36 1.4 0.04 0.49 13.25 M99 0.4 6.67 0.99 0.4 0.54 1.58 0.04 0.49 6.81 M103 9.06 2.71 1.79 0.4 0.47 1.67 0.04 0.49 7.25 M119 6.26 4.22 1.15 0.5 0.75 1.54 0.04 0.52 13.87 M33 7.23 2.51 1.29 0.4 0.9 1.5 0.04 0.72 15.15

Mn Mo P Pb S Sb Sc M1 729 7.12 729 23.42 54.55 3.59 17.12

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231– 6345 (Online) An Open Access, Online International Journal Available at www.cibtech.org/sp.ed/jls/2014/04/jls.htm 2014 Vol. 4 (S4), pp. 1693-1709/Ardalan et al. Research Article M12 980 144.12 561 51.09 147 4.01 14.68 M13 778 26.29 662 29.25 121 4.21 16.79 M16 974 8.37 864 20.56 19.99 3.67 13.54 M23 832 16.55 659 30.3 19.99 3.33 13.27 M29 1166 5.82 598 23.49 56.82 3.95 19.6 M35 764 9.64 515 25.13 19.99 2.77 9.35 M46 670 62.05 626 33.84 19.99 3.9 9.89 M52 1676 5.96 1161 75.06 26.57 4.79 22.09 M57 374 16.04 825 44.69 19.99 3.12 8.24 M65 320 14.74 785 32.89 19.99 4.01 8.54 M71 456 38.16 728 21.69 19.99 3.19 7.74 M77 908 203.36 926 31.49 183 4.43 17.39 M84 824 22.32 692 25.97 26.12 2.77 13.89 M90 1622 55.18 1241 17.47 34.33 5.54 25.39 M97 706 40.26 817 40.66 19.99 3.94 9.52 M99 776 42.91 604 33.19 19.99 4.57 14.35 M103 629 10.74 764 41.76 19.99 4.67 9.93 M119 941 32.18 712 15.66 35.03 3.85 17.71 M33 948 114.88 775 27.14 49.46 4.43 19.13 Se Sn Te Ti Tl W Cl M1 0.05 5.1 0.77 3750 1.74 0.94 0.1 M12 0.09 4.71 0.73 3609 0.56 1.08 0.1 M13 0.06 4.5 0.82 3868 0.58 0.78 0.1 M16 0.06 5.54 0.91 4542 0.499 1.08 0.1 M23 0.1 4.78 0.74 3504 0.499 0.56 0.1 M29 0.11 4.58 0.96 4645 0.77 0.87 0.1 M35 0.05 3.57 0.72 3211 0.499 0.81 0.1 M46 0.08 4.56 0.59 2795 0.78 1.03 0.1 M52 0.06 4.19 0.97 4102 0.499 0.79 0.1 M57 0.05 4.44 0.56 2870 0.67 0.93 0.1 M65 0.05 4.27 0.64 3199 0.73 0.95 0.1 M71 0.08 4.3 0.61 3309 0.63 0.92 0.1 M77 0.1 4.98 0.9 4639 0.499 0.86 0.1 M84 0.14 4.42 0.85 4112 0.51 1.18 0.1 M90 0.08 8.86 1.58 6421 0.81 1.59 0.1 M97 0.13 4.88 0.73 3790 0.58 1.19 0.1 M99 0.06 4.64 0.8 4035 1.35 1.1 0.1 M103 0.1 4.38 0.67 3528 0.68 0.85 0.1 M119 0.11 5.27 0.98 4770 0.499 1.23 0.1 M33 0.05 5.05 0.96 4474 0.499 0.499 0.1

Figure 3: Geochemical P-Q plot for naming of the granitoids of the area in use of XRF analys (Debon and Le Fort, 1983) (Ad= Adamelite (quartzmonzonite))

Figure 4: Classification of calcalkaline and subalkaline magmatic series (Irvine and Baragar, 1971)

Figure 5: Classification of calcalkaline and tholeiitic magmatic series (Irvine and Baragar, 1971)

Figure 6: Co- Th plot of Classification for magmatic series, that show high- k calcalkaline and shoshonite series for Qohroud samples (Hastie et al., 2007) © Copyright 2014 | Centre for Info Bio Technology (CIBTech) 1703

Figure 7: B-A plot for Al- saturation index (Villaseca et al., 1998)

Figure 9: Discrimination diagrams for the tectonic setting of granitoid rocks (Pearce et al., 1984)

Figure 10: Discrimination diagrams for the tectonic setting of granitoid rocks (Harris et al., 1986)

Figure 11: A1-A2 plot for A-type granitoids (Eby, 1992)

Figure 12: Petrogenesis plot for discrimination tectonomagmatic environment and kinds of orogenic or anorogenic (Batchelor and Bowden, 1985)

Figure 13: Spider plot that normalized to upper continental crust for Petrogenesis discrimination trace element (Taylor and McLennan, 1995)

3-3- Continental Rifting Evidencesin Qohroud Kashan There are evidences that show continental rifting in back arc basin is related to the origin of magma in Qohroud Kashan. 1- Volcanic rocks of the Jahaq area are belonging to alkalin series that is near the Qohroud (Tabatabayi et al., 2008). 2- According to the plots, the rocks of the area, tectonically, are located both in the area of volcanic arc granite (VAG) and within plate (WPG). 3- Verdel et al., (2011) suggest that the late Paleocene- Eocene magmatic flare- up was extention related. They propose a tectonic model that attributes the flare- up to decompression melting of lithospheric mantle hydrated by slab- derived fluids, followed by Oligocene upwelling and melting of enriched mantle that was less extensively modified by hydrous fluids. In this paper they address a magmatic flare-up similar to the mid- Tertiary event in the western United States that occurred during Paleogene time in Central Iran. He suggest that Paleogene magmatism and extention was driven by an episode of slab retreat or slab rollback following a Cretaceous period of flatslab subduction, analogous to the Laramide and post- Laramide evolution of the western United States, They evaluate the pasibility of the following mechanisms for generating the paleogene flare up: change in subduction rate, change in subduction angle, slab melting, and back-arc basin development rifting (Verdle, 2009; Verdel et al., 2011). 4- Kazmin et al., (1986) suggested that Eocene volcanism in Iran throughout the Middle East and Mediterranian regions was related to the opening of back- arc basins (Verdel et al., 2011). 5- Also in other area of Iran there is rifting such as Taromolia- Zanjan area that Dr. Ardalan concluded rifting on his thesis at this area using Evidences such as bimodality in the Harker plots (Ardalan, 2001). 6- Also there is drifting in the Qohroud – Kashan of Iran that Khodadadi (Khodadadi, 2014) concluded rifting on her thesis. She suggested when mantle plum have rising to the crust mix with arc magma and subduction zon. Evidences such as bimodality in geochemical data, high temperature 900- 1000 C, inrichment in incompatible elements including rare earth elements (REE), Nb show these rocks are derived from more depth of magma may related to rifting zone (Khodadadi, 2014). © Copyright 2014 | Centre for Info Bio Technology (CIBTech) 1707

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