نشریه علوم دانشگاه خوارزمی
سال دوازدهم شماره 2 (تابستان 1391)

In this research، based on spatial distribution and size of crystals، the role of physical processes affecting formation of the igneous rocks such as kinetics of crystallization (nucleation and growth of crystals)، dynamics of magmatic systems (e. g. mixing and convection currents) and equilibrium processes such as textural coarsening are investigated. To this end، the spatial distribution pattern (SDP) of plagioclase، amphibole and quartz crystals were quantified in the microdiorite-quartz diorites and results were combined with petrography to discuss the factors affecting plagioclase packing arrangements and physical processes operated during formation of these rocks. The study area is located in 120 Km southeast of Birjand. The 8 thin sections of rocks were processed and geometrical features e. g. length، width and centre of 3098 crystals were measured. Then، R values (a descriptive value) were measured using nearest neighbor distance method with BigR and ArcGIS software''s and the data were plotted against porosity (modal abundance of other phases in igneous rocks.) Results show that crystals have clustered SDP. The degree of plagioclases clustering is different in sections with change of crystal sizes and shapes. The origin of crystal clusters is likely to involve heterogeneous nucleation، textural coarsening and overgrowth of crystals.

The volcano - sedimentary complex in the North of Shahrekord، center of Chahar mahal and bakhtiary province as a NW-SE trend belt has located in the central part of the Sanandaj- Sirjan structural zone is composed of volcanics (basalts، andesitic basalts and andesites)، subvolcanics (dolerites and microdiorites)، volcaniclastics (tuffs، lapilli tuffs، agglomerates، volcanic breccia and tuffites) belong to Upper Jurassic، Middle Kimmerian orogenic phase. These rocks with calc-alkaline to tholeiitic affinity were erupted in a subduction environment as island arc. The above mentioned lithological unites have been affected by hydrothermal fluids with pH=8-9، T=226◦C (in intermediate argillic zone) to 300◦C (in quartz- epidote veins) under 200 bar pressure. The secondary minerals have replaced primary rock components (selective pervasive) or have occurred as vein and vesicle fillings (non pervasive). There are three alteration zones in the study area including propylitic (chloritic)، sericitic and intermediate argillic based on variety amounts of the chlorite، epidote، clinozoisite، calcite and illite. Vesicles in basalts are filled by chlorite-epidote-clinozoisite-calcite- quartz assemblages too. The investigation of mass changes show that the volcanic rocks have lossed their mass as result of hydrothermal alteration partially in chloritic zone. CaO enrichment and Na2O depletion in chloritic zone، Na2O، K2O depletion and MgO enrichment in sericitic zone، FeO، Na2O، K2O enrichment in intermediate argillic zone are key indices to determination of fossil alteration zones.

Introduction and Chah-Savar-Agha quarry، the quarry which belongs to Neyriz marble quarries complex، is one of the important economical center in the Fars province. In recent years، some slumps and instabilities have occurred in this area and this phenomenon increases the importance of structural studies and investigation of tectonic stress specially insitu stresses. Therefore، the main purpose of this research is the investigation the role of tectonic structures such as joints، fractures، insitu stress phases and effects of them on instabilities of the northern slope. By field studies and measurement the geometrical characteristics of the fractures، including dip and dip direction of joints، fillings and the number generations of filling، they are analysed by DIPS5. 1 software to achieve the structural analysis and reach to the insitu stress phases. According to the results، at least two insitu stress phases are acceptable in the area. - Releasing stress phase: this stress phase with the South West- North East trend has caused the reactivation of some old joints and creation of some young fractures in the area. The releasing stress phase has been created by rapid extraction from the quarry. - Local tensional phase: Field observations have indicated that the Northern slope was creeping in the North East direction and this phenomenon has created the tensional stress phase with the East- West trend in the area and this stress phase has created some vertical fractures with the North-South trend also. The creep mechanism in the Northern slope has been created by burden of debris which have been accumulated on the top of Northern slope. Burden of these debris has created the vertical stress that has caused the creep mechanism upon a fracture with N152/50NE identity in the South East Strike.

Production optimization is an important and challenging task in oil industry. In the present paper، we look For an acceptable setting of Intelligent Control Valves (ICVs) which leads to optimum production respect To reservoir conditions and operational restrictions. The Design of Experiment (DoE) as a structured، Organized method is used to determine the relationship between different settings affecting petroleum Production. In this context، the Taguchi method and Response Surface Method are employed and tested on a horizontal well with few ICVs، in order to maximize oil production while minimizing produced Water. The summary of approach and computational results is reported.

The Alut granitoid complex is located in the northwestern part of the Sanandaj–Sirjan zone. This complex comprises three main units i. e. monzogranite to granodiorite bodies (SiO2 = 65–77 wt %) which is widespread throughout the area، a quartz-diorite to tonalite unit (SiO2 = 52–63 wt %) exposed as two stocks and mylonitic granitoid scattered as separate outcrops through the area. NE-SW trending microquartz-diorite and NW-SE trending aplite dykes are also present in this complex. The quartz-diorite to tonalite unit has relatively high CaO،FeO، MgO، Al2O3 and low Rb/Sr، Sr/Y، and (La/Yb) N، which preclude an origin of variably fractionated mantle melts and favour a mafic lower crustal source. Dehydration melting of biotite-bearing metasedimentary sources at relatively low pressures is proposed for the origin of monzogranite to granodiorite unit. Geochemically this complex is metaluminous to slightly peraluminous، typical of I-type granites. It belongs to low K (and high K for some monzogranite samples) calc-alkaline series and displays the geochemical characteristics typical of volcanic arc plutons related to an active continental margin area (e. g. significant Nb، Ti، P and Sr depletion). Based on collected geochemical data، the Alut granitoids originated by partial melting of crustal protoliths having different compositions in a deformed active margin.

Productive and non-productive intrusive of Oligocene-Miocene age with similar mineralogical composition in Kerman porphyry copper belt exhibited important geochemical differences in terms of trace and rare earth element geochemistry. The productive intrusives are best characterized by low contents of MnO (≤0. 1 wt. %)، Y (≤18ppm)، ΣHFSE (≤100ppm)، heavy rare earth elements (Yb≤1. 9 ppm)، high Sr content (≥406-1015ppm)، high (Sr/Y≥30)، significant REE fractionation (La/Yb≥20)، as well as positive Eu anomalies (Eu/Eu≥1)، when compared with non-productive intrusives (MnO≥0. 1wt. %،Sr=184-576ppm،Y=12-50ppm، Sr/Y<30، La/Yb<15،Eu/Eu*<1). These signatures are indicative of hydrous and oxidized magmas that formed in a condition which has been different from that of the non-productive intrusives. Based on the present study، the discrimination diagrams which can be used as a tool for identification of productive intrusives، where they are accompanied by nonproductive intrusives، in other copper provinces in Iran، are as follows: MnO-Y، ΣHFSE-Y، Sr/Y-Y، Sr/Y-SiO2، La/Yb-SiO2، La/Yb-Yb، Eu/Eu*-SiO2.

The Pazanan oil field is located in Dezful embayment، 150 km south east of Ahvaz and south east of Aghajari oil field. Aghajari formation has formed surface outcrop and also the Asmari formation with 7 reservoir layers is the main reservoir rock in this oil field. In this research high fractured areas in the Pazanan oil field have been analyzed based on subsurface date and utilization of subsurface analyzes method. It seem to be the Pazanan oil anticline is an asymmetric fold with high dip in south west limb and the middle parts have been distinguished as areas with potential of fractures development with respect to longitudinal Curvature. Geometrics analysis of this structure indicate that south west limb in more parts and north east limb in middle parts have been distinguished as areas with high fractures density. Axial bending (longitudinal) of the Pazanan anticline is because of growth and propagation and combining of separate anticlines shear zone result of strike slip faults motion and old strike slip structures.