فصلنامه زمین شناسی اقتصادی
سال دوم شماره 1 (پیاپی 2، بهار و تابستان 1389)

The Cheshmeh Hafez polymetal deposit is located in Troud – Chahshirin mountain range in Southeastern Damghan. In this province, the volcanism and associated mineralization are closely related to major faults Anjilo and Troud with NW-SE trend. The exposed rocks in the study area consist of volcano clastic sequence of sandstone, tuff, volcano breccias and mostly andesitic and andesitic- basalt flows at Cheshmeh Hafez district. Alteration in Cheshmeh Hafez area is consisting of Proplilitization, Sericitization, Argillic alteration and Silicification. Mineralization occurred in three district stages; 1) quartz, carbonate with early pyrite and chalcopyrite assemblages; 2) the main stage of sulfide deposition, comprises early euhedral galena followed by galena and sphalerite, then galena, chalcopyrite, tetrahedrite, pyrite, bornite and digenite, and 3) quartz and calcite barren veins with minor pyrite and chalcopyrite. The average assays from 12 samples of Cheshmeh Hafez veins are; 0.15 g/t Au, 3.23 g/t Ag, 4.47 wt % Pb, 2.64 wt % Cu, and 1.73 wt % Zn. Fluid- inclusion homogenization temperatures (Th) in quartz fall within range of 140º-300º with salinities ranging from 4.7 to 18 wt. % NaCl equivalent. Comparison of Th versus final ice melting (Tmice) values indicates the occurrence of fluid mixing process. In order to evaluate extent of mineralization in depth, IP and RS techniques were used, which indicate the presence of mineralization in depth.

The investigated area is located 30 Km south of Sabzevar in Halakabad village. Geological phenomenons in area follow a trend of NW-SE. Mineralization consists of metallic and non-metallic (kaolin) mineralization. Disseminated and veinlet mineralization is generally associated with argillic alteration type. Pyrite is the most widespread type of sulfide mineralization in Halakabad occurrences. It usually displays a euhedral habit and have occurred at least in two generations. Calcopyrite is common in veinlets although in minor amounts. Secondary sulfuric acid weathering of the ore has generated huge surficial amounts of oxide and sulfate minerals which of hematite and jarosite are the most abundant. Geochemical exploration was conducted over both drainage geochemistry and rock geochemistry. Results show that some of the stream sediments have higher concentrations of Copper and Zinc than normal. This anomalies maches with monzonite outcrops in area. The chip rock geochemical data shows highest values in west of halakabad mine for Cu and Zn respectively 500 and 900 ppm. These data represents that all samples collected from surficial areas of east of area contain lower concentrations of Copper while sulfide mineralization is more than the other parts. Presence of favorable alteration system in region, presence of monzonite subvolcanic intrusions and regional geological criteria indicates a possible Cu-Au porphyry system in Halakabad area.

Esteghlal fireclay mine, northern Abadeh, with dominant composition of kaolinite and pyrophyllite, and annual production of over a million tons, is one of the largest sedimentary deposits in Iran. Linear Spectral Unmixing (LSU) and Mixture Tuned Matched Filtering (MTMF) processes were applied on the VNIR + SWIR dataset of ASTER for identifying the frequency fraction and distribution of clay minerals in this mine. Sub-pixel frequency assessment of ASTER data showed that distribution of pixels with higher fractions belong to the kaolinite and pyrophyllite, outcropped in two different parts of the mine. Comparison of LSU and MTMF output results showed that MTMF is more reliable to determining the relative fraction of clay minerals at the study area.

In recent days, computer is becoming one of the most essential instruments in advanced countries for the researchers and the domain of its application is going to be increased every day. Using the 3D modeling of the earth, its mine resources and the brilliant details which are given by the models, the researching and exploring groups will find out the inconspicuous and attractive aspects of the genetic structure and the geological history of these resources. In this paper which is a result of the researches done as the case study on a group of aragonite deposits in West Azarbaijan province, modeling of under study mineral deposits and the genetic approaches obtained from the models lead into explore and discover some other resources of the same minerals which is widely accepted recently in the market of decorative rocks in Iran. In modeling procedure of these resources which is a product of the geysers, the profile of these lime generating springs and their directional order on some specific hidden fracture is determined and approximate location of the new resources for the next explorations is assigned. At the moment, these assigned locations as new resources are being explored and even exploited.

Nezam-Abad area is located in southwest of Shazand (Arak) which is a part of Sanandaj-Sirjan zone. Major intrusive rocks of Nezam-Abad are quartz diorite and minor amount of granodiorite. Leucogranitic, pegmatite dykes and quartz-tourmaline veins were intruded the quartz diorite. Quartz diorites are mainly composed of plagioclase, hornblende, biotite, quartz and pyroxene as major minerals. Major minerals of leucogranite are microcline, orthoclase, albite, quartz, biotite and muscovite. Accessory minerals consist of apatite, zircon, sphene, epidote, allanite, tourmaline and opaque. The presence of hydrous minerals like hornblende and biotite in these rocks indicate that the corresponding magma initially contained >3 wt% H2O (wet magma). The occurrences of garnet and andalusite minerals suggest assimilation process. Primary textures in these rocks are granular, granophyre, and poikilitic. Secondary textures are perthite, myrmekite, sericitization, chloritization and kaolinitization. Later hydrothermal activities and tectonic strains are factors for presence of perthite texture in leucogranite. K amount for sericitization of feldspars come from the K-feldspars and chloritization of biotite. Transformation of biotite to muscovite indicates the act of K rich fluid in later stages. On the basis of chemical analysis on the intrusive rocks, it is shown that the magma was calc-alkaline, metaluminous-peraluminous and medium-K to high-K. Study of major elements in Harker diagrams indicates Al2O3, FeO, Fe2O3 and CaO decrease with increasing of SiO2 and K2O and Na2O increase indicating that fractional crystallization may have played an important role in the formation of granitoid rocks from Nezam-Abad.

Iron mineralization of Kalate Shahin is located 107 km on the Ghoochan-Neyshaboor road (in Khorasan Razavi province). Subvolcanic intrusive bodies of quartz monzonite to monzonite porphyry intruded the Cretacous limestone. Sedimentary units of the area in decreasing age include Cretaceous limestone and Eocene and Paleocene-Quaternary microconglomerate to sandstone. Mineralization in the region formed in two stages, hypogene and supergene. Pyrite, magnetite and specularite formed in the hypogene and goethite and hematite in the later. Investigation of ƒO2 and temperature conditions indicated that temperature of hydrothermal minerals in the east of the area was less than 350ºC. The amount of goethite and hematite in the west of the area is much less than the east and is frequently present as vein and veinlet associated with hydrothermal dolomite. The source of mineralization, hydrothermal solution in west of the area had lower sulfide and temperature but was more oxidized than the east. The result of geochemical analysis using AAS method for Fe, Mn, Mg and Ca elements indicated the highest amount of iron (30.4%) at the trench on the east of the area. Iron showed positive correlation with Mg at this location. There is also relation between the amount of these elements and the distance from the intrusive bodies. Therefore, the intrusive bodies of the area had no role in the mineralization. Total magnetic intensity (TMI) was measured at 742 stations on 2 grid of 20×5 meter. Map of TMI colour image along with contour, Reduction To the Pole (RTP) and upward continued were prepared using ER Mapper. Inspection of magnetic maps indicated distributed anomalies in the area, maybe related to the covered hornblend diorite porphyry which outcrops at about 40 meter apart. Due to the presence of hematite in limestone that correlates with anomalies B and C,magnetite mineralization at depth also may be the causative source of these magnetic anomalies. Therefore, drilling exploration at location of anomalies B and C is proposed.

Barika gold (and silver) rich massive sulfide deposit is located 18 km east of Sardasht, north western part of Sanandaj-Sirjan metamorphic zone. Rock units outcropped in this area are Cretaceous metamorphosed volcano-sedimentary rocks in green schist facies, and include association of meta-andesite, meta-tuffite, phyllite and slate rocks, where the meta-andesitic unit (Kmv1) is host rock to the deposit. Barika deposit is composed of stratiform ore and stringer zone. Stratiform part contains massive and banded sulfide and barite associated with subordinary silica bands underlain by stringer silicic zone. The massive and banded ore is surrounded by an extensive zone of silicic stringer veins and disseminated mineralization within strongly altered and deformed andesitic volcanic rocks. Ore mineral assemblages in stratiform part of the deposit are quite variable and consist of pyrite, sphalerite, galena, stibnite, a variety of sulfosalt minerals and gold (electrum). Ore mineral assemblages in silicic veins in the stringer zone are simpler and consist of pyrite, galena, sphalerite, tetrahedrrite and trace chalcopyrite. Average gold and silver grades in stratiform ore are 8. 3 and 420 g/t respectively and in silicic stringer veins are 0. 7 and 30 g/t. Base metal content in both parts of the deposit are less than 1%. Based on our research, Barika is an immature Kuroko type massive sulfide deposit, which contains only black ore. The Barika deposit underwent low-grade metamorphism and high grade deformation after the ore deposition event. Geologic processes appear to control the mode of occurrence of gold in the deposit. In synvolcanism stage, deposition of a gold–bearing low temperature (140-200°C) and low salinity (1-9. 6 wt% NaCl) hydrothermal fluid formed a Kuroko black ore type deposit. In the stage of mineralization, invisible gold was concentrated in framboidal pyrite and other sulfide minerals. The main effect of progressive metamorphism (D1) on gold mineralization is recrystallization of the framboidal pyrite and migration of submicroscopic gold to the crystal boundary to form electrum under low to moderate strain. Highly strain and deformation (D2) on the deposit caused the remobilization of gold and accompanied َAs, Sb, Ag, and Pb minerals and continued to form coarse-grained electrum (up to 3 mm) in open space fractures. The formation of barren silica veins (D3) and high angle normal faults (D4) are the results of retrograde metamorphism.