Iranian Journal of Geology
Year:2009 | Volume:2 | Issue:8|Papers Count:11

For studying and differentiation of geomorphological units in part of Hableh-Rood drainage basin, Enhancement Tematic Mapper (ETM+) Landsat data with the bound combination of 7, 4, and 1 in red, green and blue colors were used. For image enhancement, stretching and filtering methods used. For Facies analysis and differentiation and interpretation of photomorphic units, geology, topography, vegetation and land use maps, arial photography along with other data and field controls were used. Also for image processing, Ilwis software was used. According to the result, 44 photomorphic units were differentiated; of whose 2 are agriculture land, 3 alluvial trasses, 3 intermountain, 28 mountains and 8 hills area. The regarded scale for displaying image or among of image magnification on monitor for interpretation, units play important role in differentiates and interpretation phenomenal. The best differentiation of photomorphic units was obtained with the scale of 1:50000. This study has shown the potential of Landsat data for differentiation of land phenomenal and different facies of arid region and quick access to unit in geomorphological map.

 The Chehelkureh copper deposit is located in Kuh-e-Lunka area, about 120 km NW of Zahedan (SE Iran). The ore field extends for 1500m in N23°W direction, and is displaced by late brittle faults, striking E-W roughly. The host rocks are Eocene intercalated turbiditic greywacke sandstones, siltstones, and shale (flysch). Several stocks and dykes of granodiorite to quartz monzodiorite and granite composition intruded the turbidites, hornfelsing them locally. Primary mineralization occurred in two stages, and comprises quartz, dolomite, ankerite, siderite, calcite, and lesser amounts of pyrrhotite, arsenopyrite, pyrite, chalcopyrite, sphalerite, galena, Se-rich galena, marcasite, molybdenite, ilmenite, rutile, nevskite, and paraguanajuatite. According to drill holes, there is a reserve of copper, lead, and zinc, with an average of 1.48% Cu, 1.77% Zn, and 0.85% Pb (4.1% Cu+ Zn + Pb). Complex intergrowth textures, some of which represent exsolution textures, are common in ore minerals, indicating temperatures greater than 400oC for the formation of Chehelkureh ore deposit.EPMA results of sulfides indicate the presences of Se, and Bi. The average content of Se is 0.01% in pyrite, 0.018% in sphalerite, 0.028% in chalcopyrite, 0.025% in pyrrhotite, and 0.015% in galena respectively. Besides Bi minerals, bismuth element is present sometimes in considerable amounts in sulfides. S/Se ratio in the Chehelkureh ore deposit is lower in galena, and higher in pyrite. These ratios, as a whole, show magmatic origin for mineralization.

Permian deposits, including Doroud and Ruteh Formations, have extensive outcrops in Central Alborz. The Gaduk Section, east of Firuzkuh city provides a good example from these exposures. The siliciclastic and carbonate deposits of Permian in this section, about 348 meters thick, overlie the Lower Carboniferous limestones of Mobarak Formation and are unconformably overlain by Lower Triassic carbonate rocks of Elikah Formation. Detailed description of geometry, fossil content, sedimentary structures, and stratal surfaces in the field along with lithological characteristics, textural properties, and microfossil components of the rocks in the lab led to identification of 4 terrigenous and 13 carbonate facies. Using major characteristics of the facies, diversity of fossil content especially foraminifra and green algae, and eodiagenetic siliceous cement; these facies were formed in the 7 depositional sequences. Depositional environment of the facies were determined as a continental shelf in the Paleotethyan passive margin (North of Gondwanaland). This environment shows the characteristics of a siliciclastic shelf for Lower Permian deposits and a carbonate ramp for the Middle Permian rocks. Comparing with sequences from other parts of the world, the studied sequences were classified in second and third order types. Relative sea level fall in the Late Permian led to development of cherty–lateritic unconformity in the Permo-Triassic boundary. Cherty nodule bearing strata can be related to maximum sea level fall as an indicator for type one sequence boundary determination.

Because of cellular nature of Digital Elevation Model (DEM), it is very important in most of hydrology engineering models. In this model, pixel size is basic factor that is effects on its accuracy.In this study, we notice the role of pixel size changing in calculation of channel length as a most important hydrological parameter. Maps with scale of 1:25000 from five regions of Iran edited and then interpolated in eight different pixel sizes.For appointment of role of pixel size changing, channel extracted is compared with use of D8 model with channel of maps with scale of 1:25000 in different pixel size with a view to length, movement and fractal dimension. Result of this study showed that pattern changes where the pixel size of channel length changes. The results of fractal diminution show that the pixel sizes large than 30 meter have difference geometric pattern with real channels. Also delineation channels errors from 5 and 10 meters was lees and has high accuracy.

The study area is located in Khorasan Razavi province, north of kashmar city. The structural location of the study area along the Khaf-Doruneh Belt and near the Doruneh Fault and close to the various Tertiary magmatism caused special mineralizations throughout the studied area. The presence of petrology (calk-alkaline sub volcanic bodies), various alteration zones, presence of gold anomalies, pyrite and secondary iron oxides, in this area indicate some similarities to continental margin zones and Eocene porphyry-forming volcanics. Fluid inclusion studies (homogenization temperature between 200 to more than 400 °C with salinity between 5 to 40 %wt NaCl, 840 m depth with 200-300 bar pressure) shows some similarities to Cu porphyry and Au epithermal systems.

The Anaran anticline is located between Lurestan (in the north) and Dezful Embayment (in the south) zones in the Zagros fold-thrust belt. This anticline and adjacent anticlines are affected by the Balarud blind thrust fault zone, which is a part of Mountain Front Fault. The Mountain Front Fault is a major topographic front that can be traced along the Zagros folded-thrust belt in the Izeh, Fars, Lurestan and Dezful Embayment. The field observations, analyses of the geometric parameters and comparison of the anticline with the theoretical fault-related folding models suggest that the Anaran anticline is a fault-bend fold mode Õ that is sheared by Balarud blind thrust fault zone.

The Dalichai Formation at Balu section in Payambaran area, northern Semnan, was studied by using palynomorphs and organic matter contents in order to determine its Palaeonvironmental conditions. A total of 55 samples were collected and treated for palynological studies. The formation at this section consists mainly of shale, calcareous shale and limestone. Palynologically, productive samples contain spore, pollen grains, dinoflagellate cysts, foraminiferal linings, acritarchs, wood debris (plant tissue) and Amorphous Organic Matters (AOM). The high amount of the AOM indicates a shallow, low oxygen levels and relatively quiet environment. Based on palynofacies data, such as proportion of blade-shape to equal dimensional opaque palynomacerals, the percentage of AOM to marine palynomorphs was determined. This indicates deposition of Dalichai Formation in a shallow, low oxygenated condition with a slow rate of sedimentation. However, occurrence of marine elements testifies intermittent marine incursions. The sharp increases in abundance of chorate dinoflagellate cysts in two parts of the section indicate short-term marine incursions in these parts.

The Javaherdasht Basalts are situated in northern part of west-central Alborz. Geochemical surveys of major and trace elements and 143Nd/144Nd and 87Sr/86Sr isotopic ratios show that the source of the parent magma of basalts is from a MORB source astenospheric mantle with depleted Lherzolite composition and Spinel facies.This studies show that the basalts originated from less than 60 km depth in the pressures between 15-20Kbar which are contaminated with lower continental crust during magma rising.Due to the contamination, the basalts exhibit enriched zone properties untruth.

Study of the Faraghan Formation sandstone illustrates the development of clay cements in them. Kaolinite is by far the most abundant clay cement in sandstones and smectite, illite and chlorite are the next frequent cements respectively. Dickite also occurs as the deep burial diagenetic product from kaolinite. Formation of kaolinite is attributed to shallow diagenetic environments mainly due to feldspar alteration. Formation of chlorite and illite is attributed to deep burial diagenetic environments due to transformation of bertierine and kaolinite precursors respectively. Smectite is suggested to form in either eogenetic or telogenetic environments. The maximum burial depth estimated for this formation, mainly based on the development of mesogenetic clays (i.e. chlorite, illite and dickite), is closely corresponding with the generation of gas.