Journal title

Form E

Form F

Seperation of ferromagnetic and paramagnetic anisotropies of igneous rocks by using High-Field Analysis (HFA): case study of Malayer igneous rocks

Vahid Ahadnejad

The magnetic anisotropy of rocks results from the contributions of diamagnetic, paramagnetic, & ferromagnetic minerals. This bulk anisotropy of magnetic susceptibility, which can be rapidly measured with modern instruments, generally provides a better understanding of the rock deformation history. Different minerals in a rock can form at different times and also respond to deformation in different manners. Therefore it is useful to separate their respective contributions to the whole rock magnetic fabric. Various techniques available to achieve this separation among them measurement of the magnetic properties at high fields, above the saturation magnetization of ferromagnetic minerals, effectively separates the diamagnetic-paramagnetic magnetic anisotropy. In this paper, the anisotropies of ferromagnetic and paramagnetic components are separated using High-Field Analysis torque for 37 samples of natural rocks. These samples are igneous rocks of Malayer that are mainly composed of paramagnetic minerals (e.g. biotite and amphibole) and few portions of ferromagnetic minerals (e.g. titanomagnetite) which are located in the quratz-feldespathic (diamagnetic) context. Anisotropy of Magnetic Susceptibility (AMS) in low field analyses indicated that paramagnetic phases are the dominant control of the magnetic fabric. This is confirmed by High Field Analyses (HFA) which implied that magnetic characteristics are dominated by paramagnetic minerals, except for three samples.

Geochemistry and dating of gabbros associated with Sawlava ophiolites-NW Iran

Bahman Rahimzadeh

Gabbroic stocks and dykes associated with Ophiolitic Basalts and peridotites are outcropped in the Sawlava town area. Sawlava ophiolite is part of Kurdistan Ophiolitic complex that located in sheared zone between high Zagros and northern Sanandaj-sirjan Zone. This study focused geochemistry and dating of granular and pegmatoid gabbros that due to closing to main recent fault (MRF) some part of them found milonitic fabric. Gabbros have 47.84 to 51.65 percent SiO2 and almost formed from tholeiitic magma. Labradorite plagioclase and diopside and augite clinopyroxens with Mg# of 83.90 to 88.90 respectivly are main minerals of gabbros. Based on geochemical and geotectonic diagrams, gabbros generated from slightly deplete magma which formed in back arc supra-subduction zone. U-Pb dating of zircons presents an average age of 38.3±1.3 Ma for gabbros. Late Eocene age from Sawlava gabbros and similar gabbros bodies related to ophiolites along Zagros suture, could indicate that neo-tethyan ocean closed after Eocene in the Kurdistan region.

Geochemical and petrographical research on dolomites in Lower Cretaceous rocks, Esfahan province

The study area is located to the south, west and north Esfahan province. this research is geochemical and petrographic study of Lower cretaceous dolomites. Five dolomite type have been identified.
The first type is very fine-fine crystalline dolomite formed in near surface conditions and in early stages of diagenesis, in tidal flat to lagoonal environments. The Sr content is high (2537ppm) and Fe (8861ppm) and Mn (852ppm) is low.
The second type is fine-medium-grained, subhedral to euhedral, crystalline dolomites. Compared to the first type, Sr content is lower and Fe and Mn content is higher. This type of dolomites is most likely formed in early burial diagenesis.
The third type is medium-coarse-grained, euhedral and subhedral, crystalline dolomite and show clear rim and cloudy center. Compared to the type1 and type2, this type of dolomite contains higher Fe and Mn and lower Sr. They are likely formed in deeper burial diagenesis and by dolomitization of earlier calcareous deposits or recrystalization of first- and second- type dolomites.
The medium-coarse-grained, crystalline dolomite fill in pores and fractures, and are called "four-type" in this study. This type of dolomite is likely formed during late diagenesis and under conditions of medium pressure and temperatures less than 60-80 °C. In this dolomite values of Fe and Mn increase from the fringes of pores and fractures to the center.
The fifth dolomite type is coarse, crystalline, saddle dolomite filling pores and fractures. This dolomite

Study of fractionation trend in south Marzan Abad basic volcanic rocks based on geochemical models

Roghieh Doroozi

In the northern hillside of Central Alborz, in south Marzanabad, there are outcrops of basic volcanic rocks which attributed to Cretaceous time .In this study, effective processes on evolution of these volcanic rocks are surveyed to add on our knowledge about Mesozoic magmatisim in Central Alborz. Based on petrographical and geochemical studies, south Marzanabad basic rocks could be classified into 2 groups of basalt and andesite basalt. Geochemical diagrams imply that the magma nature is alkaline and generated in intracontinetal extensional environment. Microscopic studies, mineral chemical composition and the observed trends in geochemical diagrams of whole rocks, all are inline with fractional crystallization as a main magmatic process. Fractionation began with crystallization of olivine and pyroxene and minor plagioclase in basalts and continued with crystallization of clinopyroxene and plagioclase in andesite basalt. In addition to petrographical, mineralogical and chemical evidences, the occurrence of fractional crystallization process is confirmed by the geochemical modeling with Melts software which also let us to reconstruct the condition of fractionation process. Based on the fractional crystallization modeling in south Marzanabad basic volcanic rocks, basalts are generated by 40 percent of fractional crystallization from primary magma. Basaltic andesites also produced after the fractionation of basalts, during 70 percent fractional crystallization from the same magma. Olivine thermobarometric studies also confirm the accuracy of data which is obtained by the Melts software.

The Use of System Dynamics In Behavioral Prediction and Safe Yield Determination of Tabriz Plain

Hamid Nassery

Tabriz plain with area of 869 square kilometers is a part of the Urmieh lake's catchment. The purpose of this study is to simulate the behavior of Tabriz aquifer against various stresses and determine the permissible level for the operation of the aquifer. To achieve the above objective the system dynamics simulation method has been used.
In this regard, the required information includes ground water resources data (wells, springs, qanat), sources and consumptions after analysis to eliminate defects was given to the VENSIM PLE+ software, and a dynamic simulation model was developed. Then by define the range of allowed water table fluctuations and the allocation of extracted water under these conditions, the allowable water level and safe yield of the aquifer was determined.
According to the obtained results in the six-year modeling period, the maximum amount of monthly and annual extraction without any damage from the aquifer is 12.70 and 152.45 million cubic meters respectively. The average of minimum and maximum allowable water table level during this period are 1317.35 and 1322.34 meters respectively.

Geochemistry, Origin and Geodynamic environment Intrusion Zaker - Sorkheh Dizaj in the Southern Limb of the Tarom Subzone, East of Zanjan

Nematollah Rashidnejad Omran

The granitoid intrusion trending NW-SE, is expose in the East of Zanjan, structurally located in the Alborz - Azarbaijan zone and Tarom sub-zone. Petrographic composition of the intrusion includes a range of monzogranite, quartz-monzonite, quartz-monzodiorite to monzodiorite and in fact shows monzonite series composition. The major rock forming minerals consist of K-feldspar, plagioclase, pyroxene (augite-diopside) and quartz. They show granular, intergranular, microgranular to porphyrytic-microgranular textures. The intrusion has metaliminus high-K calc-alkaline to shoshonitic and I-type affinity. Enclaves of the intrusion have micro-granular mafic and monzodiorite, quartz monzodiorite composition, which are fine-grained than their host rock and have micro-granular porphyritic texture. According to the petrographical and geochemical studies, the magma has originated from partial melting of metasomitised sub-continental lithospheric mantle due to fluids and/or partial melts that originated from subduction edge. According to Harker Diagrams seems that monzodiorite magmas differentiation Leads to monzonite Formation And finally the Crystallization and differentiation are monzogranite. Therefore Crystallization and differentiation are the most important processes controlling rock types in the monzonite series intrusion. Tectonic diagrams indicate a continental margin magmatic arc and syn-to-post collisional intra-arc extensional environment.

Structural analysis of the Anbaran Fault, Northwest ofTalesh Mountains

Ali Yasaghi

Anbaran inlier is located at the NW of Namin city. In the inlier Pre-Paleozoic roks surrounded by young Eosen and Cretaceouse rocks.To interpret the inlier deformation and its evolution model, geometry as well as kinematic characteristic its major structurs analysed for the first time. For the faults kinematic, indicator, such as slickenside, fault associated folds and S-C structure were used. The results of analysis show that the major structurs of inlier are the Anbaran and RF1 fault at its Norht and South margins.The high angle Anbaran and RF1 faults cause thrusting of the Pre-Paleozoic Biandor and Soltanieh formation in the core of inlier over the Eocen volcanic units and Cretaceouce limeston respectively.This resulted in development of a pop-up structure that form the present morphology of the region .The fault high angele dip, and deposition of Cretaceous sediments on its hanging wall provide evidence for the fault inversion.therefor the RF1 fault is considered as the inverted anbaran fault backthrust.