فصلنامه زمین شناسی ایران
پیاپی 33 (بهار 1394)

Zagros Fold-Thrust Belt consists of several fault–related folds which important hydrocarbon reservoirs are formed in relation to their evolution. Understanding of fold geometry and its growth pattern are affective parameters in the exploration and drilling programs of hydrocarbon reservoirs. In this research, stream bed erosion pattern and quantitative morphometric indices were used as geomorphic indicators to recognition the mechanism of fold-growth. Results of geomorphic investigation reveal dominant of detachment folding pattern in the coastal Fars area. Moreover, the effect of change in the thickness of detachment horizon on the folding pattern was evaluated.

There are several intrusive plutons in the Saheb- Yapesh-khan area, which are compositionally made from mafic to acidic rocks, including granite, tonalite, syenodiorite, monzodiorite, quartz diorite, diorite and to a lesser amounts gabbros. The main rock type of the area is granite. The intrusive rocks were formed at the Island- Arc (ACM) environment in terms of tectonic setting. The parental magma was primitive and formed by low degree partial melting (less than 5%) of metasomatized mantle with spinel- garnet- phlogopite lherzolite composition. The mantle source was metasomatized by influx of dehydration of sediments and the rocks of the subducting oceanic slab. The crustal contamination had a meager effect on modification of the original magma composition. On the basis of variation diagrams of the studied igneous rocks, there are two main petrogenetic trends (mafic and felsic series) for the studied intrusive rocks. It seems that these trends are formed due to fractional crystallization and separation of amphibole and plagioclase from the primary magma.

The study area is part of Alborz-Azarbaijan zone exposed in NW Meshginshahr. The volcanic rocks, Eocene in age, include tephritic phonolite and phonolithic Tephrite. They have phenocrysts of clinopyroxene, analcime, plagioclase and alkali feldspar and set in the same minerals in the matrix. Microprobe analyses on polished thin sections were performed by using an electron microprobe analyzer for chemical analyses of the clinopyroxenes. Based on these results, it is concluded that all clinopyroxene phenocrysts are diopsidic in composition and have relatively high Mg-numbers (0.66-0.90), variable Al2O3 (3.39-8.38 wt %), low TiO2 (<2.02 wt %) and Na2O (0.36-1.5 wt %) contents and low AlVI/AlIV ratios (mostly <0.3), suggesting relatively low-pressure crystallization conditions of the magma in the storage region. Also it is revealed they formed at temperature of 1005-1080 ºC and pressure of 4-5.5 kbars. The geochemical studies of clinopyroxenes remarkes they have clinopyroxene characteristics of alkaline rocks related to volcanic arc. Existence of normal and reverse zoning in clinopyroxens deduces differentiation and magma mixing were effective factors on evolution of the area rocks.

Qaemyeh area is located in 100 km West Shiraz and 40 km north of Kazerun. Structural formed in this region is resulted from segmentation Kamarij of the active Kazerun strike-slip fault, is part of the Zagros Simply Folded Belt and consist of NW-SE trending faults and folds sub-parallel to Zagros fold belt. The study area includes two faults, one normal and right lateral component that makes deformation dextral strike-slip fault Gurpi and Pabdeh, Sarvak and the other which Dextral strike-slip fault, that makes is another deformation Asmari. Strike-slip fault, Riedel shear fractures follow the pattern and proportion of Kazeron fault have been angle. In this study slickenlines fault data in order to reconstruct the orientations effective paleostress using inversion method picked up and was investigated. The position and trend of the principal stresses normal fault, respectively σ1 is NW, S71°W, 76º, σ2 is SE, S60°E, 06º and σ3 is NE, N31°E, 70º and strike- slip fault, σ1 is NE, N31°E, 07º, σ2 is SE, S60°E, 06º and σ3 is NW, S84°W, 80º respectively. To analysis the deformation area Structural cross-section perpendicular to the direction of the structures of NE-SW, were drawn. During this scrolling, structures such as dextral strike-slip fault and fold related faults, the structures of Precambrian and periods are Cenomanian geochronology respectively. The stress field around faults is related of the Kazerun active fault.

Upper parts of Elika carbonate Formation belonging to middle Triassic in central part of structural- sedimentary zone of Alborz in East of Mazandaran province (Savadkuh, Khatirkuh and Kiasar regions) are hosted some of important F-Pb-Ba ore deposits contain of PachiMiana, SheshRudbar, Era(Alikola) and Kamarposht. Based on of field observations in study, main localization of ore bodies within carbonate rocks are as acrostic, irregular, and discordant respect to bedding that are displayed in fractures and/or karstic cavities in the form of vein, lenses and bodies. Mineralogy in studied ore deposits generally is simple and mainly composed of galena, barite, fluorite, calcite and minor sphalerite. Macroscopic and microscopic observations are shown variety of syngenetic and epigenetic structures and textures. Disseminate, stylolite and micro-veinlet textures of galena and calcite with or without other mainly minerals are recognized as syn-genetic textures respect to host rocks. Epigenetic structures and textures as open space filling type such as vein-veinlet, zebra, lamination, primary replacement and colloform are dominant textures of high-grade ores that formed main and economic zones of ore body concentration in deposits. Existence of secondary textures such as curvature and wind in triangle cleavage of coarse-grained galenas and also replacement of galena by cerussite and covellite show deformation and supergene oxidation after the main stage of mineralization. Based on current research, mineralization in F-Ba-Pb ore deposits of central Mazandaran is formed and evolved at two steps (1) primary or syn-diagenetic, and (2) main or epigenetic. According to structural signatures of ore body appearance in deposits environment and also textural evidences in macroscopic and microscopic scales, the main and economic stage of mineralization in studied ore deposits is introduced as epigenetic.

More information can be extracted from signals, using signal transform tools. Among other tools, “wavelet transform” has an increasing fortune because of its good properties. The main issue is that choosing “different mother wavelet functions” results in diverse conclusions. There are various algorithms to build a suitable mother wavelet for the analyzed signal. Along with those algorithms, there are procedures too for choosing the optimum mother wavelet among existing functions. From the latter group, the “energy matching” algorithm was used in the present paper to find the optimum mother wavelet. During the use of this algorithm, its deficiency in two aspects was revealed. To solve the problem, “zero mean transform” was chose as an extendable solution to prepare data for the used energy matching algorithm. Applying this simple transform helped us not only finding the optimum mother wavelet but also a unique one.

Short sea level transgression during the late Anisian with high fossils content in the Kopet Dagh sedimentary basin in Aghdarband tectonic window, represents the gradual transition from the late Scythians (referred to The Sefid Kuh Formation) to The Sina Formation with volcanic and volcaniclastic sediments. These sediments entitled Nazarkardeh formation, are the second Formation in exceptional facies of the Triassic which is exposured in the east of the Kopet Dagh sedimentary basin, north east of Iran and consists of a carbonate and pyroclastic rock unit that from base to top of the formation, includes limestone with marl and tuffaceous silt-sandy marls and nodular limestones with interbeds of sandstone, shale and tuffaceous marl in the lower part of this Formation. Petrographic studies, sequence stratigraphic and the determination of microfacies and sedimentary environments of this formation was performed in two sections of Kale Angur and Kale Ghalak. The horizons of carbonate and volcaniclastic sediments are derived from volcanic activity in the Turan plate at the same time and transported to the Nazarkardeh Fore-arc sedimentary basin. Microfacies in this formation include the lagoon to open marine sediments and sea level fluctuations in this formation led to determination of the 3rd depositional sequence with almost 4 ma. age. The diagenetic processes in this formation such as over growth rim cement, hematitization, fractures, dissolution and fossils shell replacement are effective in the identification of changes happened after sedimentation and often in the sequence boundaries detection.

Sheyvardagh granitoeid body is located in north of Ahar, East- Azarbaijan province, intruded into upper Cretaceous up to Eocene units, and caused the contact metamorphism and skarnificaion. This intrusive body in turn cut by veins and Quartz - applite dykes. The major minerals consist of quartz, plagioclase, k-feldspar, hornblende, biotite and clinopyroxene and pertite-antipertite, porphyry, granular and antirapakiwi textures are common in this unit. According to the mineral chemistry studies, the composition of biotite is located between stonite and sydrophilite poles and amphiboles are located in the range of magnesiohestingzite and magnesiohestingzit-hornblend. Clinopyroxenes are diopside and k-feldespar tends to sanidine pole and plagioclase lies in the range of oligoclase to andesine. Thermometry studies indicate the crystallization temperature of this body from 623°C to 750°C and emplacement pressure from 1.5 to 2.4 kb. The rocks are granodioritic and syenodioritic in composition and show has meta-aluminous nature. The producer magma of this body is shoshonitic and calc-alkaline in nature high-k properties. Al2O3, CaO, MgO, and TiO2 indicate descending pattern by increasing of SiO2. In the spider diagrams a distinct and positive anomaly of Ba, Rb, Th, La, Ta, Zr, Hf, Cs, U, Pb and Pr and negative anomalies of P, Nd, Lu and Mo were observed. The producer magma of this body has shoshonitic and high-k calc-alkaline nature and emplaced in a continental crust with high to medium thickness and influenced due to fractional crystallization or partial melting and crustal contamination. This body is emplaced in a post collisional, active continental margin setting.