Rule of Structural Factors in Formation of Porphyry Copper Deposits in South Western Part of Kerman Area , Iran

Kerman area is located in southern parts of central Iranian volcanic belt. The area under study is located in the southern part of this complex copper mineralization in the area, which is mainly porphyry type and is associated with extensive hydrothermal alteration. This area has a great potential as far as tertiary porphyry copper deposits are concerned. To the exploration of porphyry copper deposits in study area, we have analyzed the lineaments. The lineaments interpreted out from ETM + (band8) data is recognized as another method for locating porphyry type copper mineralization. There is a close correlation between photo lineament factor values and the known copper mineralization in the area. The relationship between 16 porphyry copper deposits with faults and fractures in the area is studied. Photo lineament factor assessments by using satellite photos indicate a strong relationship between a number of lineation intersection in each cell refer to an amount of average lineation in whole map (c/C ratio). In the study area, ratio of c/C even has more relationship refers to PF factor that has previously described in the papers.


Introduction
Formation of Porphyry Copper deposits are related to magmatic and hydrothermal process [1].In a mineralization province, a number of lineations and fractures can be a key for exploration, because these fractures can act as a conduit for moving of mineral content fluids.Fluids mostly move from high pressure areas towards low pressure and low temperature areas.At this case magmatic fluids instead of concentrating, spread more [2].
Faults, fractures, shear zones and different spatial stresses concentrate magma or move it toward shallow parts of the crust [3].Study of geometries and faults which are linked with porphyry copper deposits, can be valuable for finding proper location of porphyry deposits [4].Mineralization systems in volcano-plutonic belts of the earth are closely related to strike slip faults which have formed in these arcs [5].
This area belongs to Urmieh-Dokhtar province from physiographic-tectonic zoning map of Iran's sedimentary basins [6].Dominant structural trend in Urmieh-Dokhtar province is NW-SE.From tectonics view, it contains a magmatic arc that is a result of subduction to beneath of southern active continental margin of Cimmerian plate.It has marked by widespread Eocene volcanism.Urmieh-Dokhtar province has continued to south of Black Sea and Its width has increased from Naien city that many parts have covered by quaternary deposits of Dagh Sorkh Kavir, Southern Urmieh Lake, Namak and Hoz-e Soltan Lakes have formed on it.So, there are a few backland basins with Playa type sedimentation because of dip decreasing in Benioff zone (in NW part of magmatic arc).SE part of magmatic arc has formed on southwest margin of East-Central Iran microcontinent.This area is a semi-active magmatic arc and based on previous work on the salt and mud diapirism [7]- [17] and neotectonic regime in Iran [18]- [23], Zagros in south Iran is the most active zone [24]- [43].Then, Alborz [44]- [80] and Central Iran [81]- [95] have been situated in the next orders.Urmieh-Dokhtar volcano-plutonic zone is elongated from northwest toward southeast along major trust of Zagros (Figure 1).11 porphyry copper deposits have known in this zone.In Kerman province in south of Iran, there is a sub tectonic zone named Dahaj-Sardoiyeh, northern parts of Dahaj-Sardoiyeh belt that is shown by black rectangle (Figure 1) study to determine the relationship between tectonic factors and porphyry copper deposits.

Materials and Methods
The study area is situated in the southern part of the central Iranian volcano-sedimentary complex, southwest of the Kerman province.There has been folding of Lower Tertiary volcano-sedimentary rocks and emplacement of Late Tertiary granodiorite, diorite, monzonite and tonalite in the volcano-sedimentary complex.A detailed description of the geology between the Rafsanjan Belt and Sirjan Belt, in which the study area is located, is given by [96].
The Eocene volcano-sedimentary rocks consist of trachybasalt and trachyandesitic tuffs, lava flows and porphyrites, trachyandesitic and trachybasaltic rocks, tuffaceoussediments, and andesitic and basaltic rocks.The sedimentary rocks in the volcanic sedimentary complex are mainly sandstone and, less frequently limestone.The intrusive rocks are granodiorite to tonalite.Most of the plutonic and volcanic rocks are hydrothermally altered and mineralized in places.Argillization, sericitization and propylitization are the most common types of hydrothermal alteration in the area.Cretaceous colored melange is the oldest and the Quaternary alluvial deposits and gravel fans are the youngest exposures in the study area.Cretaceous sediments are mainly flysch.Eocene volcanic rocks are subdivided into the Bahr-e-Aseman complex and the Lower Razak, Middle Razak and Upper Razak complexes.The study area has 16 porphyry copper deposits that are listed in Table 1.
Using [98] [99] models indicate good relationship between fractures with faults and lineations.Study area is strongly tectonized and fault systems cannot be categorized as a simple shear and should be divided into 4 trends: 1) Faults with east-west trend; 2) Faults with north east-south west trend; 3) Faults with north-south trend; 4) Faults with north west-south east trend.The oldest faults of the area have east-west trend and later faults with trend northeast-southwest trend, were created.The youngest faults of the area are north-south faults.The study area as a shear plain right lateral fault system is surrounded by Rafsanjan fault in the north and Shahr-e babak fault in the south [100].These faults are strike slip with oblique vector.Fault-parallel contraction and fault-parallel simple shear are the most common faults in the area.As the first faults had east-west trend, thus shear was acted as fault-parallel contraction.After shifting stress trend, it has changed to fault-parallel simple shear.Fractures and lineations with using of some special filters were studied.The result is shown in Figure 2.
Using photo lineament factor (PF) for exploration of groundwater in fractured hard rock is common.Results of such techniques can be useful for exploration of porphyry deposits as well.Number of lineation, their length, and number of intersection of lineations can be used to analysis of these structural phenomena.[101] has introduced the following formula to calculate photo lineament factor: Map showing faults in the study area.Black points are porphyry copper deposits described in Table 1.

Results and Discussion
Linear analysis of a 2 × 2 km grid cell size for the intended study area and regional lineament map was implemented.The following parameters were determined in a separate cell in 1042.Photo lineament factor in the study area was calculated and drawn by using satellite photos and softwares like Surfer and ArcGIS.With respect PF, Photo lineament factor was calculated in each cell (Figure 3).The results show that there is strong relationship with location of porphyry copper deposits and PF.Also the area with high PF amount has coincidence with surface alteration manifestations As can be seen in the map of the intersection of porphyry copper deposit formation lineaments an important role in fertility in the region.So as to adapt relatively well between the porphyry deposits in the region with the highest concentration of intersection in the region can be seen.
For a better result, different factors collaborated with distribution of porphyry copper deposits [102]- [104].The results show that the ratio of c/C, in above mentioned formula, has better collaboration with the porphyry copper deposits even from PF (Figure 4).A recent study shows that the intersection of faults and fault can be multiple ways to create environments for the porphyry intrusive magmatic.

Conclusion
Local fractures are the major reason for transferring hydrothermal fluids towards the surface of the crust.As even in the area without surface alteration manifestations that has high amount of PF, porphyry copper deposits are visible.The intersection of strike slip faults forms the best location of concentration of hydrothermal fluids and this position has improved in the study area.In this study, spatial relationship between 16 copper porphyry deposits with faults and fractures of the study area has studied.The Strong relationship between lineament factor and location of porphyry deposits has deducted.The major propellant to transfer of mineralized hydrothermal fluids is smashed rocks and local fracturing.These fractures can create surface alterations as well as.Although in some   places with the lack of surface alteration and high photo-lineament factor, porphyry copper deposits are evidences.The relationship between numbers of lineation intersection in each cell refers to an amount of average lineation in a whole map (c/C ratio).In the study area, ratio of c/C even has more relationship referring to PF factor that has previously described in the papers.A recent study shows that the intersection of faults or linements can be multiple ways to create environments for the porphyry intrusive magmatic.

Figure 1 .
Figure 1.Physiographic-tectonic zoning map of Iran's sedimentary basins, modified from [1].The study area is shown in the black rectangle.

Figure 2 .
Figure 2. Map showing faults in the study area.Black points are porphyry copper deposits described inTable 1.

Figure 3 .
Figure 3. Contour map of PF distribution in the study area.

Figure 4 .
Figure 4. Contour map of c/C ratio distribution in the study area.
x, y according to UTM, wgc 1984, zone 40 N