The remote sensing data plus field and petrological studies have provided possible separation of lithological units with high accuracy in the study area. The Multispectral data was used for differentiating of lithological units (Figure 3),

main alterations (Figure 4), structural trends, hydrothermally altered minerals (Figure 5), surface mineral identification and mapping (Figure 6). The main litholigcal units and structural trends were identified as a linear body trending NW-SE direction parallel to the major shear zone of the area. The results of remote sensing (RS) and petrographic data provided a means for classification of lithological units into 3 units. The granitoid stock consists of monzogranite, granodiorite unites in the south but quartz-diorites and quartz-monzogranites in the north of the area. Analysis of remote sensing data and field studies suggested that mafic to intermediate and acidic intrusive-extrusive sequence is present in the study area (Figure 6). Moreover, hyperspectral data was used to distinct the location of hydrothermally alterated minerals in Malek Siah Kuh area. Hematite and arsenopyrite with minor quantity of limonite and goethite are found in the study area.

The igneous complex at Malek Siah Kuh area is comprised of a wide range of mafic and intermediate to acidic intrusive-extrusive sequences. The complex can be subdivided into three groups: 1) mafic unit (gabbro-basalt), 2) Intermediate rocks (diorite-andesite suite and much less trachyandesites) and 3) felsic unit (granitoide rocks). The predominant units in plutonic rocks are chains of diorite and granodiorite suits. The diorite rocks in the Malek Siah Kuh batholith are exposed in the north-eastern part of the study area. These rocks are medium to coarse grained, characterized by granular, ophitic to subophitic textures. Although all types of diorites in the study area are mineralogically similar but the dioritic unites comprise varying lithologies of altered gabrodiorite, meladiorite, mesodiorite and leucodiorite. The principal constituent minerals in these rocks are plagioclase (andesine) (44% to 56%), orthoclase (8% to 16%) and β-quartz (5% to 15%), but augite (5% to 15%), hornblende (15% to 20%), epidote, calcite, zoisite and clinozoisite, occur as minor constituents. The XRD analysis of dioritic altered rocks revealed the assemblage of calcite, zoesite, clinozoesite and epidote. In meladioritic rocks, saussuritization products (calcite, clinozoesite and epidote) occur as altered minerals. The most abundant accessory minerals are

magnetite, titanomagnetite and opaque minerals. Although intermediate rocks occur as stocks (small plutons) and thick dikes but a large pluton is observed in the south part of the study area.

The volcanic rocks consist mainly of andesite, trachyandesite and basalt (Figure 7). They are dark-colored to brown with phenocrysts of plagioclase (labradorite to andesine), mafic minerals (hornblende, Pyroxene) and alkali feldspar with porphyritc and gleumeroporphyritc textures. The more Ca-rich members of the plagioclase series (phenocrysts) are completly zoned with inner zones altered to fine cryptocrystalline mixture (sausuritization). The process of sausuritization had been produced calcite, zoesite, prehnite, clinozoesite and epidote. In volcanic rocks (andesites and trachyandesites), the fine groundmass consists of plagioclase (andesine), hornblende, pyroxene (augite) and alkali feldspar. Moreover, titanomagnetite and opaque minerals are present as accessory minerals (Figure 8).

Granitoid unit is the most abundant plutonic rock in the area and consists mainly of granodiorite but includes other rocks such as monzogranite and quartz monzonite. Granodiorite rocks are often found related with typical hydrothermal minerals and they vary from medium to coarse grained. In this group, the dominant mineral assemblage is plagioclase (oligoclase) (40% to

50%), K-feldspar (orthoclase) (15% to 20%), β-quartz (25% to 30%) with minor phases (biotite, sphene) (10%) plus chlorite as a product of alteration of biotite

and hornblende. Porphyritic andesites and trachyandesites (as the main volcanic unit in the study area) occur in the central and eastern part of the area.

Geochemical data from the igneous complex have been used to characterize the petrogenesis and tectonic setting of the plutonic and associated volcanic rocks of the study area. Major oxides, trace and rare earth element (REE) abundances of 15 samples from the complex were analyzed by XRF, ICP-MS and AAS (Table 1). The result data indicate that unaltered trachyandesite is silica oversaturated with SiO₂ ranging from 55.46% to 60.45% and alkali contents (K₂O + N₂O) ranging from 6% to 10% but the intermediate rocks of the area exhibit a narrow range of SiO₂ content (55% to 60 wt.%).

Moreover, the amount of SiO₂ in granodiorites ranging from 63.31% to 64.1% and total alkali contents from 5.56% to 6.46%. As a result, these granodiorites belong to high-K calcalkaline series. The granodiorite is characterized by high LREE contents and low HREE contents. All of the geological and petrological evidences suggest that quartz-diorite, quartz-monzodiorite and granodiorite rocks in Malek Siah Kuh apparently form as a result of fractional crystallization of source magma.

In the TAS diagram [29] , the most rocks plot in the fields of sub-alkaline basalt, andesite and trachyandesite (Figure 9). However, variations of silica versus the FeOt/MgO and standard AFM diagram (Figure 10) as well as silica versus

K₂O (Figure 11) showed that most of the samples are calc-alkaline in nature. Thus, due to chemical and petrological relationships, these rocks are considered part of the calc-alkaline province which extends from Lut block into Sistan area. Therefore, the geochemical characteristic of igneous complex in Malek Siah Kuh was related strong subduction components. In the complex, TiO₂ increases with decreasing SiO₂, that consistent with magma evolution during differentiation from a mafic magma [30] . Despite the clear link between the compositions of plutonic complex that can be related to metaluminous or peraluminous but some volcanic rocks in the Malek Siah Kuh area are shoshonitic. They are enriched in LREE and depleted in Ti, Nb and Ba.

Plot of major elements versus silica (Figure 12) indicates that the rocks of the complex show smooth variations with gradual decreases in CaO, FeO_(total), and TiO₂ with increasing silica. The positive correlation of Na₂O and incompatible elements (Ni, Zr and La) with SiO₂ (Figure 12 and Figure 13) and the negative

correlations of TiO₂, MgO, CaO, FeO_(total) and P₂O₅ with SiO₂ (Figure 12 and Figure 13) show the impact of differentiation of magma in the magmatic evolution of igneous complex in the Malek Siah Kuh area. Beside these plots, the result of XRF and ICP-MS in Harker diagrams showed the effect of differentiation process as well as contamination phenomenon.

Diorite rocks of the complex are characterized by high SiO₂ and Al₂O₃ contents but intermediate alkali and MgO contents. Geochemically, diorite-andesite unit is predominantly calc-alkaline and metaluminous in characteristics. These

compositional characteristics suggest the parental magma of andesitic composition and this kind of high-aluminum magma is typically produced in subduction related settings particularly at continental margins [31] . Although the igneous complex in Malek Siah Kuh, crystallised from basaltic magma, however, granodiorites and trachyandesites are peraluminous and may have formed by assimilation of felsic continental crust.

Although, field relations of intermediate plutonic and acidic rocks do not indicate a direct petrogenetic link, but lithogeochemistry investigations showed some similarities in trace and rare earth element abundances. These evidences may indicate derivation from similar silicate melt source during differentiation from a mafic magma [30] and assimilation of crustal rocks. Immobile, incompatible elements (such as Ti and Zr) exhibit highly significant positive correlation coefficients (r) in cogenetic lavas, even when altered or metamorphosed [32] . In another case, the plot in the magnesian granitoid field indicates hydrous, oxidizing condition of the magma. The origin of magnesian granitoids has been interpreted as related to subduction processes [33] .

Petrological studies and geochemical data (including REE and trace element analyses) has highlighted the fact that magma mixing was not responsible for the formation of intermediate rocks. In contrast, the trace element analyses and enrichment of LILE of the igneous complex relative to HFSE is suggesting calc-alkaline magmatism and involvement of strong subduction components.

The igneous complex shows a wide range of Zr (70.3 to 143.9 ppm), Y (11.1 to 14.7 ppm), Sr (276.6 to 1237 ppm), Rb (74.3 to 158.2 ppm) and Nb (10.2 to 14.5 ppm) values. Moreover, these rocks contain high concentrations of the HFS elements, thus reflecting an enriched source. The enrichments in Th and LREE relative to HFSE and HREE in the primitive gabbros are characteristic of subduction related magmas [19] . The most obvious consequence of the geochemical study of REE elements is enrichment of LREE in compare of MREE and HREE (Figure 14). These evidences indicated the relative importance of differentiation process in rock forming minerals (e.g. plagioclase and hornblende). Therefore, based on the petrological evidences, the igneous complex was most likely derived from partial melting of subducted Sistan seafloor followed by fractional crystallization and wall rock assimilation of continental crust.

The intrusive rocks and associated volcanic suits of Malek Siah Kuh related to Cu-Fe-Au mineralization in the Sistan area are characterized by high SiO₂ (≥59.8 wt.%), Al₂O₃ (≥15.5 wt.%), sodium (Na₂O ≥ 3.2 wt.%), low Yb (≤2 ppm), Y (≤12 ppm), high La/Yb ratio (≥11.5) and Low HFSE (Nb, Ta) (Table 2). Broadly, the characteristics of these rocks are geochemically similar to adakite. In addition to the petrological aspects, the chemical trend of major and trace elements from intermediate plutonic to acidic rocks showed arc related active continental margins (Figure 15 and Figure 16). The rocks in the study area are complex and in order to take account of this complexity, the diagram of Sr/Y versus Y (Figure 17) was used to distinguish adakite type rocks from normal arc igneous rocks. This is a practical illustration that plots of MgO wt.% vs. SiO₂, Sr vs. (CaO + Na₂O) and Sr/Y vs. Y show the chemical differences between low silica adakite and high silica adakite types (Figure 18). Thus, plotting La/Sm ratio vs Sm/Yb ratio diagram (Figure 19) would allow for deducing the possible mantle source in the study area.

It is clear that the presence of igneous activities (in the form of diorite-granodioritic complex), hosting the mineralization indicate a role of magma in the generation of ore forming magmatic hydrothermal systems. Adakites in subduction zones are now recognized to be particularly favorable for Cu-Au mineralization [8] . Porphyry Cu-Au deposits are generally derived from sulfur-rich, highly oxidized magmatic systems, with oxygen fugacities (fO₂) between the nickel-nickel oxide (NNO) and magnetite-hematite oxygen buffers [12] . [12] suggested that only slab-derived adakitic magmas or supercritical fluids would have a high oxidation potential to generate epithermal and porphyry Cu-Au deposits.

Cu and Au mineralization in Malek Siah Kuh is mainly associated with diorite-granodiorite complex and by hydrothermal activities. In the study area, wall

rocks are commonly altered and polymetallic hydrothermal veins are common in the rocks of the complex (Figure 20). Based on set of petrological and geochemical-mineral deposit relations, three distinct stages of mineralization process can be recognized in the Malek Siah Kuh area. 1) The first stage is related to differentiation of primary magma followed by metal enrichment as well as subsolidus leaching by hot fluids. 2) The second phase appeared by ascending of the gas-rich magma (reduction in gas pressure) and the release of sulfur and arsenic. Mineralization is associated mainly with hydrothermal alteration. 3) The final stage was completed by hydrothermal activities leading to the generation of sulfidation (formation of gold and copper sulfides) and associated polymetallic (Cu, Au, Fe) mineralization. Polymetallic mineralization formed quartz or chalcopyrite and veins associated with a number of polymetallic (Cu, Fe) sulfides.