مجله بلور شناسی و کانی شناسی ایران
سال هفدهم شماره 4 (پیاپی 38، زمستان 1388)

Permian bauxite deposits in north of Saqqez occurred as stratiform lenses of carbonate within Ruteh Formation. Field evidence show that these deposits formed in swampy environment in which the water table was relatively high during their evolution. According to petrographic considerations, these deposits contain ooidic, pisoidic, spastoidic, nodular, skeletal, and spongy textures and have an authigenic origin. Based on mineralogical studies, these deposits are composed of minerals of diaspore, boehmite, corundum, hematite, goethite, magnetite, rutile, anatase, montmorillonite, quartz, illite, pyrophyllite, talc, nacrite, dickite, k-feldspar, muscovite, chlorite, chloritoid, plagioclase, pyroxene, amphibole, chamosite, gypsum, calcite, and fluorite. The presence of high quantities of silicate minerals indicates immaturity and poor draining system of these deposits. Comparison of the range of stability fields of major constituent minerals of the bauxite ores with the pH and Eh variations of natural environments show that the surface waters with oxidizing-acidic nature and underground waters with reducing-basic nature played crucial roles in developing of these deposits. Combination of mineralogical and geochemical data of immobile elements indicate that Saqqez bauxite deposits were developed from alteration and weathering of basaltic-andesitic rocks.

Eocene volcanic rocks in NE of Ordib, have a very good exposures near and along the Turkmeni-Ordib fault. These rocks, that are situated in the inner part of the Central Iran and margin of the Yazd block, comprise trachyte, trachy-andesite and basaltic trachy-andesite. Trachy-andesite is the pervasive rock unit. Rock forming minerals of these rocks are chloritized olivine, plagioclase, pyroxene, mica, amphibole, K-feldspar, quartz, ilmenite, magnetite and calcite. The most important mineralogical characteristics of the studied trachy-andesites are wide range of minerals in one rock sample, including two types of clinopyroxene, mica, plagioclase, sanidine, formation of reactionic clinopyroxene and calcite around the quartz, and oscillatory zoning of feldspars and amphiboles. Chemistry of clinopyroxenes and biotites with whole rock geochemical analyses, reveal that these rocks are similar to the continental volcanic arc rocks. Petrography and mineral chemistry demonstrate the magma mixing occurrence in formation of these rocks.

Kaj-Rostam Abad, Dashtak and Do Ab salt domes are located around Ardal and Farsoun village. This area is situated in High Zagros range (Chaharmahal and Bakhtiary Province). The study area is composed of Lower Cambrian volcano sedimentary complex including basalt, basaltic andesite, andesite, trachyte, pyroclastics, evaporite rocks and Precambrian sedimentary units. According to the mineralogical and petrographic studies of High Zagros igneous rocks and related salt domes, they have complex mineralogical composition. The mineral assemblages in these rocks are formed during three stages, 1- Magmatic stage (plagioclase, clinopyroxcene, and apatite), 2- Late magmatic stage (amphibole, biotite, quartz, albite, calcite and sphene) and 3- Vein mineralization stage (quartz, albite, epidote, amphibole, calcite and garnet). Based on amphibole crystal chemistry, actinolite (Si = 7.87-7.93, CaB>1.5, CaA<0.5, (Na + K)A<0.5) have been distinguished, which is stable in wide range of temperature (320-520ºC) and total pressure 2 k bar. Studies of fluid inclusions in quartz veinlet, from altered volcanic rocks, were shown the high salinity of hydrothermal fluids. Fluid inclusions studies show three phases included liquid, vapour and solid. Also quartz crystals have a lot of inclusion of actinolite needles. The thermal range, 310 to 330 ºC in 42.93% salinity is distinguished for the formation of these quartz veins. The composition of chlorite, epidote and garnet are determined picnochlorite; pistazit and grossular-andradite respected and also the composition of plagioclases are mainly albite. On the base of thermometric studies, those metasomatic mineral are stable in thermal range of 300-500ºC.

Ellipsoidal huge granitoidic batholiths of Zahedan, with NW-SE trending, located in south of this city which is intruded in low metamorphosed Eocene flysches (eastern Iran flysch zone). This batholith has two compositional terms: an extensive intermediate-acid term includes diorite - granodiorite with igneous source (I- type origin) and a low extent crustal and hybrid origin acidic term (H-type) mostly contains biotite-granite. The intermediate¬¬-acid I-type term has calc-alkaline and metaluminous nature, enrichment in LREE and LILE and depletion in HREE and HFSE. The negative anomalies in HFSE and positive anomalies in LREE, LILE and especially Pb revealed an igneous mantle origin, especially the role of Sistan subducted oceanic crust and its overlaying mantle wedge in the genesis of this batholith. Also, the role of the continental crust (flysch and greywack metasediments) in contamination of magma has been proved. In addition, the same evidences indicate a calc- alkaline, peraluminous nature, a crustal (resulted from partial melting of flysches and greywacks) and an hybrid origin (mixing of the differentiated part of I-type magma with the anatectic crustal acidic melt) for acidic biotite granite term. Present day 87Sr/86Sr ratios of three samples of this batholith vary from 0.7049 to 0.7065 and their initial 87Sr/86Sr ratios range from 0.7045 to 0.7047 with average 0.7046, verifies these different sources. These data confirm an I-type magmatic origin (melting of mantle or lower crust) for the diorites-granodiorites. Discriminative tectonic diagrams also indicate a volcanic arc granitoids setting (VAG) for this batholith. Andesitic-dacitic dikes with same composition to intermediate-acid I-type term occur in this batholith and its metamorphosed host rocks. These dikes are comagmatic with I-type part's of the pluton and show a syn-to late relations with formation and intrusion of the pluton.

Masjeddaghi area is located about 35 km east of Jolfa, north of East-Azarbaidjan province. Field and mineralogical studies show that quartz-diorite subvolcanic stock and quartz-andesitic volcanic rocks in this area were altered by both hypogene and supergene hydrothermal solutions. Alterations are genetically affiliated with four groups of (1) quartz, (2) sulfide, (3) sulfate, and carbonate veinlets and micro-veinlets. The principal hypogene alteration zones recognized in the area are (1) potassic; (2) potassic-phyllic; (3) phyllic; (4) phyllic-argillic; (5) intermediate argillic; (6) propylitic; and (7) silicified. Two zones of supergene alterations were identified: (1) leached and oxidized cap and (2) supergene sulfide blanket. The hypogene copper sulfide ore minerals in order of abundance are chalcopyrite, bornite, and chalcocite that were developed mainly in the potassic, potassic-phyllic, and phyllic alteration zones. The supergene minerals that are intimately related to hypogene alteration zones include kaolinite, goethite, limonite, Mn-oxides, jarosite, malachite, azurite, covellite, and chalcocite. Considerations indicate that the supergene sulfide blanket in this area has not been well-developed and does not have considerable thickness and ore tenor.

Astaneh granodiorite intrusion, located at south west of Arak, includes an abundant rounded and rarely ellipsoid microgranular enclaves composed of gabbro, diorite and quartz diorite. The diameter of enclaves ranges from a few millimeters to 40 centimeters. These enclaves are very fine-grained and show chilled margins. The size of crystals decreases gardually from center toword margin. The chilled margin is an evidence of rapid magma cooling once the enclaves were surrounded by host felsic magma. Occurrence of the mafic microgranular enclaves within the felsic rocks with disequilibrium textures including: poikilitic texture of K-feldspar megacrystals, ocelli quartz rimmed by zones of fine-grained accumulations of early formed minerals, zoned plagioclase, mafic clots, acicular apatite, small lath-shaped plagioclase within large plagioclase, all indicates the mixing of two magmas. Based on microprobe analyses, the plagioclase crystals show a variable composition from oligoclase to andesine in granodiorite and from andesine to labradorite in enclaves. They have essentially normal zoning. The enclaves and their host rocks, geochemically, are not different from each other and enclaves are enriched in Cr, Ni, and Co. In addition, the enclaves display the HREE enrichment compared to their host granodiorites. Therefore, it seems that the enclaves and granodiorites have been originated from two various depths of magmas with different depths which were located adjacent to each other by magma mixing process.

The Sachun Formation (Paleocene-Lower Eocene) is mainly composed of carbonates and evaporates that were deposited in shallow-marine evaporitic mudflat environments. The Sachun Formation in the study area has been divided into three units including: lower evaporate; middle bioclastic limestone and upper evaporate. It is mainly composed of diagenetic gypsum, which originated from dehydration of anhydrite precursor. This gypsum in the Sachun Formation generally displays alabastrine and porphyroblastic textures with corroded anhydrite relics. Petrological studies reveal that the most important diagenetic processes affected the middle Part of the Sachun Formation are dolomitization and evaporate mineralization. Four types of dolomite, ranging from early to burial diagenetic environments, were identified. These are including very fine-to-fine crystalline (D1), neomorphic dolomite (D2), fine-to-medium crystalline euhedral to subhedral dolomite (D3) and pore- and fracture-filling dolomite (D4).

CdS: Mn nanocrystals were obtained by nucleation and growth in colloidal solution. Their mean size range between 3.96 nm and 4.90 nm. The structural properties were studied by the use of X-ray diffraction (XRD). Phase transition between the hexagonal structure and cubic structure was evidenced to be a function of synthesis temperature. The mechanism of the phase transition also was revealed by two-step annealing for 2h.

In this article, the thermodynamic properties of Bi¬2212, as a function of oxygen pressure and temperature vaviations, have been studied. The results showed that variation of lattice parameters are directly' a function of temperature and conversely function of oxygen content. The experiments were set up at room temperature to 820 and different oxygen pressure from 5, 10, 50, 100 and 500 mb. It was found that the crystal structure of the Bi-2212 is stable from room temperature up to 815 and oxygen pressure of 10 mb but at 820, it committed decomposition and its crystal structure completely ruined. It was found that as a result of decomposition of some of the elements of the compound does interact with quartz and put it in a fragile position.

MA-II area is one of the most important parts of Cu-Au porphyry mineralization at Maherabad prospect area. Subvolcanic intermediate intrusive rocks (Upper Eocene), monzonite to diorite in compositions, intruded telescopically and are mostly altered. Monzonitic porphyries had major role in mineralization. These intrusive rocks are highly altered, have dense stockwork veinlets, and show highest geochemical anomalies. Hydrothermal alteration zones are: Quartz-sericite-pyrite, silicified-propylitic, propylitic, carbonate and silicified zone. Mineralization occurs as stockwork, disseminated, and hydrothermal breccia. Stockwork is the most important type of mineralization. Veinlets found within quartz-sericite-pyrite zone are: quartz, quartz-pyrite, quartz-pyrite-chalcopyrite and pyrite-chalcopyrite ± quartz. Veinlets within silicified-propylitic are: quartz-pyrite ± chalcopyrite, quartz-pyrite ± magnetite, quartz-pyrite-chlorite and quartz-magnetite. The density of quartz-sulfide veinlets is about 30 per m2 (in center of MA-II in quartz-sericite-pyrite alteration zone). Most of sulfide minerals were oxidized. Secondary Fe-oxides are seen up to 15% in some places. Compositional variations of elements within MA-II area are as follow: Cu = 22-1073 (ppm), Au =16-886 (ppb), Mo = 5-54 (ppm), Zn = 40-754 (ppm), Pb = 14- 148 (ppm), As = 8-128 (ppm), Sb = 0.1-9 (ppm). High concentration of Cu and Au associated with high density of veinlets in quartz-sericite-pyrite zone in the center of MA-II area. There is positive correlation is between Cu and Au anomalies and veinlet density. Based on the obtained data, MA-II area is a part of porphyry Cu-Au deposit.

The Karmozd coal mine in Mazandaran Province (Iran) is one of the largest and oldest active coal mines in Central Alborze Coal Basin. A complete geochemistry and mineralogy characterization of Karnozd coal has been conducted in summer, 2005 by sampling of coal, coal tailing and country rock coal Basin.The coal layers (Lias) is embedded in the middle of Karmozd litostratigraphic unit. It is composed of a sequence of fine to coarse grain sandstone, and fine grain conglomerate along with shale and argillite. These coals are classified as low sulphur, ash group. Mineralogy and geochemistry results indicate that, excluding P2O5, all main oxides are related to the existing minerals within the coal layers. So that on the basis of correlation matrix, cluster analysis and principle component analysis (PCA), a strong and meaningful relationship exist between the amount of "SO3-Fe2O3" and "CaO-MgO-MnO" which classify them into two distinct groups. The first group is originated from syngenetic pyrite and the second one from epigenetic calcite and dolomite. Presence of minerals such as clay minerals, quartz and anatase with detrital origin cause the relationship between oxides of "SiO2", "Al2O3", "Na2O+K2O" and "TiO2" become much weaker than other oxides. On the basis of our study, the amount of minor and rare elements except Cl, are related to inorganic material in coal. As the origin of "heavy metals", "V-Rb" and "Y, U, Th, W, Mo, Zr, Ce, Nb, Ba and Sr" related to sulfide minerals, clay minerals and rock source respectively. The concentratin of TiO2 and most minor and trace elements in Karmozd’s Coal are much more than that of the world coals.

Acid sulfate soils in Western Australia commonly occur in coastal regions. One of the greatest threats to coastal environment is the disturbance of acid sulfate soils due to urban development which can lead to widespread acidification of lands and streams and subsequent economic losses onsite or in adjacent areas. Surface sampling from different landforms of the study area and analytical results of XRD, SEM and VNIR indicate that morphological and surfacial minerals variations, due to oxidative sulfide weathering processes in affected landscape. In dry season, the surface mineralogy of salt affected zone is dominated by halite, gypsum, barite and importantly, iron oxyhydroxides crusts (ferrihydrite, schwertmannite). The oxidative weathering of the jarosite with rapid oxidation of Fe2+, can generate iron oxyhydroxides and acid. The visible near infra-red (VNIR) reflectance spectra of the surface minerals from salt affected zone and acid sulfate soils horizon, showed spectral differences expressed in the VNIR region due to absorption bands of iron oxides and hydroxides. The spectral difference can be utilized for regional scale mapping of coastal acid sulfate soils disturbance due to urbanization in Pinjarra area via hyperspectral and multispectral remote sensing.

The study area is located in northeastern Iran (south of Mashhad). Paleo-Tethys Ocean opened during Silurian time and subduction under Turan plate was started in Late Devonian. By Late Triassic (225 Ma) there was no Paleo-Tethys left on an Iranian transect, therefore Turan plate obducted over Iran Plate. Two stages of low grade regional metamorphism are exposed, that are related to Hercynian (Late Paleozoic) and Cimmerian (Jurassic) orogenies. The Paleo-Tethys remnants (meta-ophiolite and meta-flysch) were intruded by Sangbast monzogranite. Chemically, monzogranite is moderately peraluminous S-type granitoid. It has low values of magnetic susceptibility [(5 to 11) × 10-5 SI] therefore it is classified as belonging to the ilmenite-series of reduced type granitoids. Monzogranite is characterized by strong light rare earth element (LREE) enrichment and less low heavy REE (HREE). All samples have very small negative Eu anomalies (Eu/Eu* = 0.62 to 0.88). Total REE content of monzogranite is between 212-481 ppm. The result of U-Pb zircon age dating of monzogranite is 201.3 ± 3.6 Ma (Upper Triassic, Rhaetian time). The initial 87Sr/86Sr and 143Nd/144Nd ratios for monzogranite is (0.706776 and 0.512219) when recalculated to an age of 201 Ma, consistent with the new radiometric. The initial 87Sr/86Sr and 143Nd/144Nd ratios for slate is (0.720613 and 0.511601) respectively when recalculated to an age of 201 Ma, consistent with the new radiometric results. Initial εNd isotope values for monzogranite is -3.13 and the slate is -15.19. Based on radiogenic isotopic data and REE monzogranite magma originated either from lower continental crust which was very different from slate or it is originated from mantle and contaminated in continental crust during ascending.

The Ghoshchi batholith, ~150 km2 in size is a granitoidic pluton, which intruded the Permian country rocks, in Sanandaj-Sirjan Zone, NW Iran. This granitoidic pluton is covered by Oligocene-Miocene sedimentary rocks known as Qom Formation. The Ghoshchi batholith comprises five plutons with following compositions: (a) gabbro-diorite (b) biotite granite, (c) alkali granite, (d) syenites, and (e) aplitic dikes. Gabbro-diorites are the oldest intrusive unit and have interaction zone with biotite granites. These rocks have within-plate tholeiitic nature. Graphic, microgranophyric, and perthitic textures can be found in alkali-feldspar granites, indicate their shallow emplacement depth and hypersolvus nature. Alkali-feldspar granites geochemically are high-k alkaline, metaluminous to mildly peralkaline. The alkali-feldspar granitic rocks contain lower Al2O3, CaO, Fe2O3, TiO2, Ba, Rb, and Sr but higher SiO2, Na2O, K2O, Nb, Th, Y and Zr than biotite granites samples. Alkali-feldspar A-type within-plate granites were presumably formed by high degree of fractional crystallization of mantle derived mafic magmas. Plagioclase and amphibole are two main fractionated minerals. The Alkali-feldspar granites fall into the A1 group (mantle derived) suggesting an anorogenic tectonic setting. Biotite granites and syenites are peraluminous and have crustal source.