مجله یافته های نوین زمین شناسی کاربردی
پیاپی 16 (پاییز و زمستان 1393)

Dashtak Anticline is situated in west part of Tang-e Chowgan in Kazerun Region. To determine the microfacies and sedimentary environment of the Asmari Formation in this Anticline, two sections were measured and sampled systematically in north and south flanks of the anticline with the thicknesses of 310 and 350m respectively. Detailed petrological and paleontological studies led to the recognition of 13 microfacies. The microfacies of the north flank consist of O1, B1, B2, B3, B4, B7, L1, L2, L3, L4, L5 and the microfacies of the south flank consist of O1, B1, B3, B4, B5, B6, B7, L1, L3, and L5. The depositional environment of the Asmari Formation in these sections was interpreted as a carbonate ramp (including outer, middle and inner ramp), which the most of sediments have been deposited in the inner ramp environment. The age of the Asmari Formation in this region was determined as Rupelian- Chattian. It overlies the Paleocene-Eocene Pabdeh Formation and underlies the alluvial deposits of recent time.

The study area is located at the west of the Urmia Lake and nearby Urmia Township. At the area an individual volcanic dome is observed that the main summit of it is the Bazow Daghi. Different pyroclastic and volcanic products (acidic to moderate in composition) are showed at the region, but dacite is dominant. The major minerals include plagioclase and amphibole with microlitic to hyaline matrix. Poikilitic and over growth textures of plagioclase crystals are regular. Geochemical studies show that the rocks are dacite to trachy-andesite and have calc-alkaline series affinity. LREE/HREE ratio is high. Depletion in HREE, HFSE and Ta, Nb, Ti against to enrichment in LILE and Sr, K, Ba and volcanic arc setting, are the other results. The geochemical studies show that crustal contamination has important role at the Bezow-daghi magma generation. In fact this is the first introduction of volcanic rocks of the Bezow-Daghi to geological society of Iran.

The parameters of the electrical conductivity, calcium, chloride, magnesium, sodium, sulfate and bicarbonate contents, TDS and SAR obtained from groundwater chemical analysis were used to evaluate the quality of under ground water resources in the Northwest plain of Kaboodarahang. The data were interpreted from 18 samples of water quality in the distribution network of the selected villages in two periods (November 2008 and August 2009) using diagrams of Scholer, Piper, Wilcox, and Durov, and map of the hydrogeochemistry were performed. These studies have shown that the majority of the water resources for agricultural activities are classified in the category C2S1 and C3S1 (Conductivity Sodium Adsorption Ratio). Also this study remarks appropriate to acceptable quality for agricultural purposes. In criteria, drinking water quality in the plain is acceptable based on hardness quantity (279-500) and the Scholer graph. Water quality for the industrial activities has corrosive characteristic in all parts of the especially in Northwest of the Kaboodarahang plain.

Determining the level of thermal maturity of the organic matter (OM) is a main step in the source rock evaluation. The present study provides an example of application of three different analytical techniques including Rock-Eval pyrolysis, Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GCMS), for thermal maturity assessment of the Kazhdumi Formation in Yadavaran oil field. For this, a total of 17 cutting samples from the Kazhdumi Formation were collected systematically from three wells in this oil field. The samples were analyzed using Rock-Eval 6 apparatus and two samples (KUK-535 and HOS- 420) were selected for complementary GC and GCMS analyses. Tmax values obtained from Rock-Eval pyrolysis show a relatively narrow range of variation (421-436 °C) with an average value of 428 °C which puts the samples in the early stages of oil generation window. Maturity sensitive parameters derived from GC (CPI) and GCMS analyses [20S/(20S+20R) and

/(

+) ratios for steranes and Moretaen/Hopane and Ts/Tm ratios for terpanes] are consistent with maturation level corresponding to the main oil generation window. However, maturity parameters based on the aromatic compounds correspond to the early oil window. According to these results, the Khazhdumi Formation has experienced a relatively low level of thermal maturation and is just about to enter the main stage of hydrocarbon generation in the Yadavaran oil field. Our conclusion not only excludes the role of younger source rocks (Pabdeh and Gurpi formations) in contributing to the discovered accumulations, but also suggests other deep source layers (e.g. Sargelu and Garau Formations) as the source for hydrocarbon reserves encountered in this oil field.

Fluorite mineralization occurred in Central Alborz in Elika and Tizkooh Formations. The genesis of these deposits are considered to be epigenetic to sedimentary-diagenetic type. The obtained results show that all sedimentary-diagenetic and epigenetic fluorits are with similarities normalized patterns. These similarities can be considered from solution, transportation or recrystalization of former fluorites (sedimentary-diagenetic) epigenetic fluorite originated. The pattern similarity of fluorite and host rock, it can be concluded that remobilization of F element occurred and differential patterns between fluorite and igneous rock described their independency. In Kamarpohst ore deposit, the amount of REE is increasingly from fluorite zone to alteration and finally to basalt. Also the highest amount of REE identified in basalt and the lowest amount find in fluorite. Moreover, there was a complete similarity between normalized pattern of basalt, alteration halo and fluorite vein in Kamarposht deposit. This can show the leading of REE from the basalt and transported to fluorite vein. The dissimilarity in normalized pattern in black shale, sandstone and fluorite can be explained as differently origins. This result can be supported by the low amount of REE in sandstone and shele.Because of negative anomaly of Eu and positive anomaly for Ce, the environment of fluorite in Elica Formation was reduction.

In order to lithostratigraphic, microbiostratigraphic and paleoecologic study of the Gurpi Formation, Tang-e Zanjiran section located at Southwest of Kavar (southeast Shiraz) in Fars Province, has been selected. The Gurpi Formation in the Tang-e Zanjiran section with a thickness of 362.5 meters consists of calcareous shale, marly limestone, limestone, shale and marl, and can be subdivided into five informal members. The Gurpi Formation overlies the Ilam Formation conformable and overlies the Pabdeh Formation disconformable. In this research, 188 samples including 148 samples belong to strict samples and 40 samples belong to soft samples were studied. According to foraminiferal studies, 56 species belonging to 48 genera of planktonic foraminifera were identified. Based on studied foraminifera, the Gurpi Formation in the study section has Santonian-Middle Maastrichtian age. The Gurpi Formation in studied section is comparable with Caron's (1995) biozonation and can be considered 7 biozones based on planktonic foraminifera, biozones 1-6 belong to the Gurpi Formation and biozone 7 belongs to the Pabdeh Formation as follow:1- Dicarinella concavata Total Rang Zone.2- Globotruncanita elevata Partial Rang Zone.3- Globotruncana ventricosa Interval Rang Zone.4- Radotruncanacalcarata Total Rang Zone.5- Globotruncana aegyptiaca Interval Rang Zone.6- Gansserina gansseri Total Rang Zone.7- Morozovella velascoensis Total Rang Zone.Based on life-depth of identify fauna from Zanjiran stratigraphic section, three groups of cretaceous morphotype belong to epicontinental sea fauna, shallow water fauna and deep water fauna were identified. The Comparison of identified fauna from Gurpi formation with cretaceous biogeographic province and paleogeography map, it can be resulted this lithological section was precipitated in tethys province and warm weather as well, therefore, the condition of sedimentation could be in a deep-water environment with more than 100 meters.

The thickness of the Permian sequence in Pir- Eshagh Stratigraphical section were measured about 1400 meters, which the lower 100 meters, belong to Dorud formation and the thickness of Ruteh and Nesen formations 1100 meters, and 200 meters respectively. The lower boundary of the sequence lies on the volcanic rocks of Devonian (Andesite- Dacite), nonconformaly and the upper ones into the yellowish laminated limeston of the Elika formation continously of the early and middle Triassic. In order to study the above mentioned sequence, we systematically selected 220 thin sections from the lower bound up to the upper bound based on lithological changes in a perpendicular direction.19 types and 21 genera of 10 families of non- Fusulinid Foraminifers, and 10 types and 5 genera of Fusulinid Foraminifers’ Families- including Ozawainellidae, Schubertellida, Schwagerinidae and Stafellidae- were recognized in the thin sections. According to Foraminifers’ transmittancy, there were 3 Assemblage Biozones and based on Stratigraphical conditions and fossilised contents, we could define the ages of Asselian- Sakmarian, Morgabian- Midian and Dzhulfian for Dorud, Ruteh and Nesen formations, respectively.

The downstream-fining trend in river-bed sediments occurs due to the hydraulic sorting and grain erosion. Downward decrease in velocity and stream power causes selective sediment entrainment which results in a fining trend in the grain size. However, some discontinuities occur in this trend. In this study, five controlling factors which cause these discontinuities were tested in the studied rivers: side sediment sources, change in the basin lithology, mining, fault and basin slope. The first factor causes two types of discontinuities: 1- abrupt increase in the grain size (due to confluence of a gravel-bed side channel) and 2- a temporary coarsening trend (in case of side-channel screes). Mining (i.e. river sand and granule) results a temporary increase in the fining trend and occurrence of fault (causes abrupt increase in the grain size). Change in the basin lithology also causes abrupt increase in the grain size (if the downstream rocks are less resistant to erosion).