فصلنامه زمین شناسی ایران
پیاپی 29 (بهار 1393)

Binalud Mountain Ranges is a thin skinned fold- thrust belt that is formed during Cimmerian (Late Triassic) and Alpine (Mezozoic- Cenozoic) orogenies as a consequent of collision between Iran and Turan plates. Structurally، this fold–thrust belt were consists of several thrust sheet and thrust faults. Thrust faults are verging S-SW and younger to the south. In order of ageing and their characteristics، thrust faults can be divided into three systems. The first (older) system consists of ductile thrust faults with antiformal stack duplex geometry. The second one includes ductile-brittle thrust faults. Thrust faults in this system cut and emplaced older thrust system and show hinterland dipping duplex geometry. The third (younger) system includes quaternary thrust faults in the south foothills of Binalud Mountain Ranges. Thrust faults in this system are brittle and are probably members of an S-vengeance leading imbricate fan. Based on forland stratigraphic models، syn-orogenic clastic assemblages in post Triassic stratigraphic column are used for determination of the age of generation and activity of thrust systems. On the basis of this study، first system is a result of Cimmerian and early Alpine orogenies، while the second one formed due to middle Alpine orogeny and third system is formed during late Alpine orogeny.

Loess is a particular type of silty soils with porous structure and weak cohesion which has been deposited over different periods of Quaternary. From the geological engineering view points, these soils are problematic ones whose main geological engineering feature of these soils is their erodibility and collapsibility. Loess soils are the main deposits cover north of Golestan province. These soils have spread across 4200 square kilometers. In this study, in order to examine and identify the loessic soils, undisturbed samples were collected and transferred to the lab and then Atterberg limit, specific gravity, grading, percentage of lime, specific density, rate of consolidation, and shear strength parameters were determined. Soil collapsibility was also determined using the results of the double oedometer tests. According to the unified standard, these soils are categorized in CL and ML groups. Furthermore, based on Clevenger classification, they are placed in the category of clayey loess and silty loess. The amount of calcium carbonate in these soils ranges from 12 to 22.3 percent and demonstrates low shear strength parameters in saturated condition. The double oedometer tests results demonstrate that the soils are prone to collapsibility. The results of soil dispersion tests reveal that the depression, which is due to the presence of sodium carbonate, does not have any influence on erosion of mentioned soils; therefore the high erodibility of these soils is basically a mechanical phenomenon which can be attributed to special texture and grading of loesses.

Qatruyeh metamorphic complex in SW of Iran is located in NE of Nayriz in eastern border of the Sanandaj-Sirjan metamorphic zone. The complex consists of different schists, carbonate metamorphic rocks, quartzite, metasandstone and metavolcanics. Zagros fault movements appear as north-south Qatruyeh-Darehbid fault in the western part of the complex and is composed of a shear zone with carbonate mylonites as a main rock unit. In this research, the shear zone introduced and thermometry of deformation estimated based on twins of calcite in carbonate mylonites. Microstructure studies, based on morphology and twin width of the calcite crystals, show crystal- plastic deformation in calcite, which formed mostly mechanical e-twinning. The width of the calcite twins in studied samples range between 0.5-15 microns with density of 10 to 55 twins in millimeter. Based on experimental and mineralogical studies, temperature of the deformation estimated between 250 to 300 ˚C. Paragenesis of minerals in schists show that metamorphism developed up to green schist to lower amphibolite facies and followed by dextral sense of main faults of the area as dynamic metamorphism.

The study area is located in the West of Anguran lead-zinc mine in Zanjan province, in the central Iran zone. The metamorphic rocks of the area include chlorite schist, epidote-amphibole schist, mica schist, marble, quartzite and metamorphosed gabbrodiorite. Metapelites are the focus of the present study, since they have recorded mineral appearances and deformational phases due to suitable composition. Petrographic studies show that three types of metapelites, including biotite schist, garnet schist and muscovite schist are present. Retrograde metamorphisms, owing to pressure and temperature decrease during exhumation are recorded in the Kuhe Arqoon rocks. The main deformational features include andaluse extinction, mineral stretching, pressure shadow and preferred orientation of minerals. Using petrographical studies and considering relation between structures and porphyroblasts and matrix (microstructures), three main deformational phases were determined for the area, among them the second deformational phase was the strongest. This deformation has produced the main foliation in the rocks. The weakest phase was the third deformational phase, which was not accompanied by metamorphism. Contemporarily with D1 deformational phase, M1 metamorphic phase occurred, crystallizing chlorite, muscovite, quartz, biotite and garnet. M2 metamorphic phase was coeval with D2 deformational phase. Mineral assemblage of M2 is biotite, muscovite, quartz and garnet. During the weak D3 deformational phase, chlorite is formed with weak orientation in the rocks.

Lower Oligocene and Miocene deposits in Zagros include several formations with considerable lithological changes and faunal diversification. To study these formations more accurately and identifying the boundary among them, 414 samples of Halegan well #1 on the southwest of Qir were studied. Lower Oligocene and Miocene deposits of Halegan well #1 with 414 meter thickness; consist of argillaceous limestone, dolomite, and limestone with intercalation of marl and gypsum and formed the Pabdeh, Asmari and Gachsaran formations. The upper parts of Pabadeh Formation at its upper section include planktonic foraminifera with the age of lower Oligocene Foramtion has Rupelian age and covers conformably the lower part with late Eocene age. The upper boundary of the Pabadeh Formation is conformable with the Asmari Formation. Based on Thomas (1948) definition of the Asmari Formation, in the Halegan well, the Asmari Formation consists of the lower (Oligocene) and middle Asmari (Aquitanian). The upper boundary of the Asmari Formation is unconformable with the Gachsaran Formation. Based on paleontological studies of the lower Oligocene-Miocene deposits of Halegan well, 32 genera and 48 species of benthonic foraminifera and 13 genera and 21 species of planktonic foraminifera were identified and five biozones can be correlated with Wynd’s (1965) biozones 55,56,57,59,63. In ascending order they are: 1-small Globigerina spp. assemblage zone (No. 55) 2-Lepidocyclina-Operculina-Ditrupa assemblage zone (No. 56)3-Nummulites intermedius-Nummulites vascus assemblage zone (No. 57)4-Austrotrillina asmariensis-Peneroplis evolutus assemblage zone (No. 59)5-Rotalia-Elphidium assemblage zone (No. 63)

Mahour ore deposit is located in eastern margin of Lut Block, 130 Km west of Nehbandan. Hypogene sulfides of Cu, Pb and Zn mainly occur beneath an oxide zone in depth. Altered dacites are the most important host rocks for these sulfides. Rock units are mainly Eocene andesite, andesite-basalt and dacite lavas and Eocene pyroclastic deposits (tuff and lithic tuff) in the area. The rocks are calc-alkaline and geochemically belong to continental margin tectonic setting. Pyrite, chalcopyrite, galena, sphalerite and a silver-rich mineral were formed in fractures and other open spaces as well as vein by hydrothermal solution Chemistry of these minerals and distribution of Ag, Pb and Zn in them were studied by an Electron probe micro-analyzer (EPMA). These minerals show variation in chemistry and some of them contain silver. This type mineralization in Mahour shows characteristic between base metals veins and low sulfidation epithermal deposits.

Nowadays, wavelet analysis has many applications to identify and analyze the transient boundaries and waves, such as image borders and earthquake waves. Detection of discontinuities in the sedimentary sequences and identifying the boundaries of sequence stratigraphic surfaces are one of those applications. In this study, wavelet analysis was used to analyze wirline logs data, such as GR, NPHI, RHOB, RHOZ, THOR / URAN and multimin data such as anhydrite percentage volume, in which the data vary in sequence boundaries. Different types of sequence boundaries impact on different types of logs. The wireline logs are affected by structural and lithological changes; thus, we cannot identify those boundaries using a kind of correlation coefficients. In this study, a combination of coefficients for the wireline logs is used. This combination offers a good way to automatically determine the borders fairly accurate. The best results are obtained from the coefficients combination of GR, NPHI, RHOB (RHOZ) logs and the anhydrite percentage volume multimin, and also, the coefficients combination of GR, NPHI, RHOB (RHOZ) logs and thorium to uranium ratio (THOR / URAN) graphs. Comparison between the results of this study in Kangan and Dalan formations of South Pars gas field with the other proved methods show the capability of this technique in combination of data.

The study area with considerable sandstone outcrop is located north-east of Khuzestan province. The aim of this study was to investigate hydrogeological status to find out factors affecting the springs discharge rate. To reach the goal, the stratigraghy, lithology and structural assessments were undertaken in the area, and also water sample collection was carried out. The results indicated that there is a positive correlation between springs occurrence and fracture density. The data also revealed that in areas where sandstone thickness is remarkable and fractures well developed, aquifer reservoir as well as spring discharge is promising. The hydrochemical data showed that water quality is controlled by stratigraphy. Correlation between sulfate and calcium ions (R=%90) proves that gypsum and anhydrite dissolution process, caused sulfate water type in the study area.