JOURNAL OF SCIENCES (ISLAMIC AZAD UNIVERSITY)
Year:2005 | Volume:15 | Issue:57 (GEOLOGY ISSUE)|Papers Count:11

Kohian pluton is located 32 km north-east of Zanjan in Tarom area. This pluton has emplaced in volcanoclastic rocks of Karaj Formation (Eocene) indicating a younger age.Data analysis of Kohian pluton in various tectonomagmatic diagrams show a similarity to continental arc granites or post collisional granites. Even in some cases it has some of the characteristics of intraplate, and rift related or epirogenic intrusive rocks.The presence of two groups of acidic and basic rocks(bimodality) and the lack of geochemical relationship between them(Daly gap) in most of the diagrams, as well as the absence of normal increasing or decreasing trends of elemental oxides with respect to silica during the fractional crystallization suggest a separate origin for the formation of each groups of rocks. In other words, after the Pyrenean orogeny, in a extensional phase, a sodic alkali basaltic magma originated from the mantle asended the crust through the active faults and caused partial melting and anatexy of the crust.This process led to the formation of a potassic and acidic magma, an indication of the role of post collisional tectonic setting. Bimodality and Daly gap observed in rock groups are considered the characteristics of continental rift environments.

The Elikah Formation crops out northeast of Jajarm in Ozon Mountain in eastern Alborz (Binalud Transitional zone) and attains a thickness of up to 216 meters. This formation consists of carbonatic and siliciclastic facies and was deposited in platform environment at Early to Middle Triassic (Scythian-Ladinian) period. The Elikah Formation disconformably overlies a thick laterite-bauxite horizon (2 m) of Late Permian age. This laterite-bauxite horizon also disconformably overlies limestones of the Mobarak Formation with Early Carboniferous (Visean) age. The Elikah Formation is covered disconformably by the Shemshak Formation of Late Triassic (Norian-Rhaetian) to early Middle Jurassic age. There is a red, thick bauxite horizon (7 m) at the base of the Shemshak Formation. The laterite-bauxite horizons in lower and upper boundaries of the Elikah Formation show sedimentation gaps (continental erosion) at these boundaries. The gap between the Elikah and Shemshak Formations is related to Early Cimmerian orogenic phase, which had resulted from the collision of the Iran and Turan plates. This collision in the Jajarm area probably occurred at early Late Triassic (Carnian) time.

Karst is the result of different processes in limestone terrains, under climatic, geological and hydrological conditions. At the region under survey which is a part of Zagross Karst phonemena is the result of internal (geological structure and litology) and external morphodynamic (climate, beigbt, vegetation and time) process. In this article, the researcher has put his attention on study of effective factors of region karstification, he also introduced the major karst morphic landscapes and their foie on absorbtion and convection of meteoric water and water table feed has been discussed. Karst features and landscapes at the region have an important role in absorbtion of meteoric water and water penetration, so they are very imp rot ant in estimation of underground water resources and balance of water of the zone. The results indicate that wherever karst forms have developed in Lordegan basin, penetration water and underground water resources especially in case of springs have increased. In fact it is the karst surface forms that justify the level of the water amount of region springs. So it is very important to have detail recognition of karst features in the region to prepare a better or even optimal utilization plan for water resources of the region.

The Shazand watershed is at 40 kilo meters south west Arak city, this basin is part of sareband city. This area in view water resources is important areas in Markazi province. The mean of this research distinguish Tectonic properties and relationship with genes and development of Karstic aquifere. Meteorology, geology, geophisic, hydrology and hydrogeology properties and methods of Karst study did for example research on spring for distinguish karst structure. Research results show the shazand karst origins are two tectonic and meteoric processes. The shazand karst formed in limbe of a cynclinal. Karst lithololgy formed massive Limestone's k3, marly limestone k4 and reef limestone's k5. Karst hydrologic regime relat to karstic aquifere greatness. Major and minor chanels of ground and meteoric waters apparent as single, duplicate, and triple discharge regimes. Therefore karstic aquifere areas different in view development.

The aim of geochemical aspects in ABBAS ABAD occurrence was to detect the occurrence's outcrops, mineralization dip, although, the optimum model of mineralization is obtained and the prospective areas were detected. Furthermore, considering of geological and tectonics features, sampling grid is designed. After analysis of samples, the upstream rock type effect was eliminated. Uni Variate, multivariate analysis and correlation coefficient were measured. In the final stage, the geochemical maps with anomalous area were drawn, and mineralization depth with viewing of erosion surface was detected.

This research presents an applied workflow and results of an integrated study which included contributions from Petrophysical, Geological, Geophysical and Reservoir Engineering aspects. We provide input data for a high resolution Geo-statistical Inversion with Porosity Co-Simulation study of gas saturated, Lower Cretaceous Sandstones of Kopet-Dagh basin on GONBADLI structure in North Eastern of IRAN. The study formed part of a project for NIOC-EXP Directorate to deliver an initial deterministic inversion of a 3D- Seismic dataset acquired over the GONBADLI field followed by a Geo- Statistical Inversion and with Porosity Co-Simulation. Petrophysical data of nine wells to be incorporated into the study. The final result are three porosity reservoir models in depth that tie the well data and take advantage of the 3D-Seismic data acquired in the area. The advantages of this technique ( by using two complicated software -RMS & JASON ) over traditional approaches to building reservoir models is that the high vertical resolution of the well data can be powerfully combined with the high lateral resolution of the seismic data. The result is a detailed and accurate reservoir model that makes use of all available data.Up-scaling of the 3D property models has been performed and provided an Eclips-ready set of models for flow simulation and risk analysis under development processes. Quantification of uncertainties in geophysical measurements such as Impedance and Porosity is necessary for complete risk analysis. This is an important consideration in both exploration and reservoir characterization. We have shown that the methods of Stochastic (SGS and SGCCS) can be used to define limits to the expected values of porosity in Lower Cretaceous-gas-saturated sandstone. Essential and unique to the proposed method to reduce uncertainty is that the 3D output result fully honors the input well Logs, geologic model and seismic-data. The method generates multiple realization (PIS, PSO, P8S), allowing a full 3D analysis of uncertainty of the output results from the Geo-statistical Inversion process. This method at GONBADLI field (DI zone) has provided an improved view of the reservoir connectivity which was not possible using just the well or seismic data. This technique has added confidence to the future production drilling program. Better estimation of gas volume in sandstone layer of Shurijeh formation (Upper and Lower DI member) and detection of permeability barrier between two parts of this interval have improved just by above integrated workflow.

Seismotectonic characteristics of any seismogenic region are closely related to the geologic and geodynamic conditions in that region. The numerical analysis of earthquake distribution can be used to study changes in the geodynamic and seismotectonic behavior of a seismogenic region. In this research a new and effective method was used to quantify the earthquake distribution in several seismogenic regions of Iran during 1977 to 2000. Seismogenic zones with small fractal dimension indicate spatial clustering of shocks, whereas a large fractal dimension suggests that the events tend to propagate in the whole region. The results also reveal a pronounce change in the geodynamic behavior of the seismogenic region before and after the mainshock. A systematic scanning of the seismic catalogue allows the calculation of fractal dimensions in successive time intervals, representing the temporal evolution of the seismotectonic pattern, and therefore shedding new light on the problem of earthquake prediction.

The Lower Palaeozonie sequence is well-exposed in Kuh-e-Saluk, 2km, northern Ghelli village. In ascending stratigraphic order, this sequence has been divided into Mila (591m), Lashkarak (250), Ghelli (1140m) and Niur (160m) formations. Although this investigation has been carried out on other palynomorph groups, but my attention has been made on Scolecodont micro fossils. Therefore, 200 surface samples were selected from the Lashkarak, Ghelli and Niur formations. These were treated in the palynological laboratory of exploration directorate of National Iranian Oil Company. Fortunately, all samples contain well-preserved and abundant Scolecodont microfossils. In this study a total of 17 species were encountered that they have good abundancy and I should say that this study is focused only on Niur Formation. Three Scolecodont biozones were established in this area. The zones 1 and 2 occur in the Ghelli Formation, indicating the Middle and Late Ordovician age and zone 3 occurs in the Niur Formation and suggeste the early Silurian age (Llandovery) for Niur Formation. They are consistant with those of acritarch biozones (Ghavidel-Syooki, 2001). Among the established families belong to the Scolecodonts, two families of Polycheataspidae and Paulinitidae have more genera and species rather than other families. (the Paulinitidae family is studied in another paper). The critical Scolecodont species from Niur Formation in this study are: Atraktoprion cf. eomutus, Kalloprion ef. triangularis, Protarabellites ef. staufferi, Protarabellites ef. reetangularis, Polyehaetaspis cf. wejstropi, Polyeheataspis cf. gadomaskae, Kallioprion sp. , Moehtyella sp. , ... etc.The encountered Scolecodont genera and species were compared with those of contemporaneous strata from Sweden, Poland, Italy, Estonia and the United States of America. This comparison reveals broad similarity between above mentioned countries. Therefore, the Scolecodonot microfossil can be applied as a useful tool for Biostratigraphy and Palaeogeographical concepts.

Sedimentologhy studies of Karaj alluvial fan caused the climate were surveyed in the time of sedimentation of alluvium of a,b,c in plio- plioctocen. Existence of pyroxene and plagioclase with rounded quartz (with different properties and degradation level) in alluvium of a and c indicate ancient sedimentary cycles, fast transportation and sedimentation. Observation of unanalyzed pyroxene and plagioclase indicate moisture conditions in source but fast transportation and sedimentation have prevented for continuing. The percentage of chlorite is more than the other cley minerals and also observation of pyroxene in alluvium of a,b,c indicate the lack of wet conditions in Karaj sedimentary basin. Considering the lack of moisture in Karaj sedimentary basin. The source of mixed- layers of clay minerals can not be neoformation and transformation. So they have inheritage origin. Considering the kind of minerals in alluvium of a,b,c and the color of sediments. The climate was cold and dry with short period of warm and dry in Karaj sedimentary basin in plio-plioctocen. Existence of debris flow in alluvium of a,b,c and inheritance sources of clay minerals indicate wet conditions so the climate of Karaj Water -shed was cold and wet in plio-plioctocen.

In this paper, we have measured several Geomorphic indices such as Hypsometric integral, Asymmetry factor, Stream length-gradient index, Mountain- front sinuosity and Ratio of valley-floor width to valley height to the assessment of relative tectonic activity levels in the Alborz - Central Iran border zone ,from the east of Varamin to the east of Semnan. In addition, older and younger Alluvial fans have partitioned and then, relationships between the river morphology and active tectonics have investigated.Therefore, Attary, north Semnan, Narkan, Namakdan and Garmsar fault fronts are in fault fronts are in the second class of relative tectonic activity level. The Parchin fault front has a relative tectonic activity level between the first and the second class .Also, the Garmsar fault is the most active mountain front fault and its western part is the more active than the eastern part. Because, it has seismic records and there is a suddenly change in Hablehrod river pattern from meandering to braided.