مجله یافته های نوین زمین شناسی کاربردی
پیاپی 11 (بهار و تابستان 1391)

Darzi-vali bauxite deposit of the Bukan (south of West-Azarbaidjan province, NW of Iran) developed as semi-continous stratiform layers and lenses within carbonatic rocks of the Ruteh Formation (Upper Permian). Based on physical characteristics, in one of layers considered, four bauxite types were recognized which are, from bottom to the top, (1) brownish red ore, (2) greenish cream ore, (3) greyish geen ore, and (4) dark green ore. Based on petrographical considerations, the ores of this deposit contain pelitomorphic, pseudo-breccia, fluidalcollomorphic, pisoidic, nodular, ooidic textures, and allogenic clasts. Mineralogical data indicate that the major rock-forming minerals of bauxitic ores include diaspore, boehmite, pyrophyllite, illite, goethite, hematite, chamosite, kaolinite, rutile, anatase, muscovite, calcite, dolomite, chlorite, corundum, and quartz. The presence of high quantities of silicate minerals indicates immaturity and poor draining system during development of this deposit. Thedistribution pattern of REEs (normalized to chondrite) display differentiation and enrichment of LREEs relative to HREEs and Eu weak negative anomalies during bauxitization processes. Calculations of absolute weathering index (AWI) with assumption of Th as an immobile monitor element and the upper continental crust (UCC) as parent rock along with pattern of changes of Ce anomaly and (LREEs/HREEs)N and (La/Yb)N ratios in studied profile indicate that changes of pH, mineralogical control, adsorbtion, scavenging, and protolith heterogenity played important role in distribution of REEs in the ore of this deposit. Correlation coefficients between elements suggest that concentration and distribution of REEs were controlled by illite, muscovite, and secondary phosphates.

For estimating the rock strength and brittleness, Schmidt rebound hammer hardness value (SRH) is a useful and inexpensive technics. Brittleness depends on rock strength indicating the resistance of rock to elastic deformation. Since the direct methods for measuring of brittleness were not standardized, indirect methods such as Schmidt hammer were used in engineering geology. For this purpose, Schmidt rebound number, uniaxial compressive strength and Brezilian tensile test of seven granite rocks outcrops in Borujerd area were measured. Also, B1, B2, B3 and B4 concepts of brittleness and brittleness index (BI) as well as their relations with Schmidt rebound hammers hardness value (SRH) of the rocks were determined (in natural water content). The results show a good positive corrolation among Schmidt rebound hammers hardness value (SRH), brittleness index (BI) and brittleness concepts of these rocks(r2>0.7). Borujerd granites according to brittleness classificatoin system fall in to slighty brittle. The maximum and minimum brittleness index value in dry condition of rocks are 4.94 and 3.13, respectively. The study shows that the brittleness of the rocks decrease with an increase in water content. In saturation condition, the minimum brittleness concept(B4) is 5.27 Mpa. Monzogranites having B4
28 Mpa are very brittle and hard for drilling.

The study area is a part of the Sanandaj-Sirjan metamorphic belt comprising regional and contact metamorphic rocks. The injection of the Alvand Batholith and intrusive body of the South West Malayer (South of Tuyserkan) into pelitic host rock has produced contact metamorphic rocks in the area. Metamorphic sequence is composed of slate, phyllite, schist, spotted schist, cordierite- bearing hornfels, metavolcanic, marble and metacalc– silicate. Pelitic rocks are the most abundant type of rocks. Regional metamorphic zones contain chlorite, chloritoid- chlorite, biotite and garnet zones and contact metamorphic zones contain cordierite, cordierite- andalusite, cordierite- k-feldspar± fibrolite zones.In fact, evidence suggests that following regional metamorphism, this area has been affected by intrusive bodies and contact metamorphism has been occurred. This zones show increase in metamorphic grade towards intrusive bodies. Field, microscopic and geochemical evidences show that the protolith of metamorphic rocks in the study area contain shales and siltstones with the interlayers of sandstones, intermediate- basic volcanic rocks and limestones.

The parameters of the electrical conductivity, calcium, chloride, magnesium, sodium, sulfate, carbonate and bicarbonate, TDS and SAR from groundwater chemical analysis were used in order to evaluate the quality of underground water resources in the North and Northwest plain of Khoy and the south part of the Gharaziaoddin plain, near the Khoy ophiolitic complex. The chemical quality of the data analysis from 31 wells in two periods (dated late Mehr 1389 and dated late Khordad 1390) by diagrams of Scholer, Piper, Wilcox, and Durov, and map of the hydro-geochemistry was performed. These studies have shown that the majority of the water resources for agricultural activities are classified in the category C2S1 and C3S1. Also this study was indicated moderate to good quality for agricultural purposes. In addition, drinking water quality in the plain is approximately good based on hardness quantity and the Scholer graph. Water quality for the industrial activities has corrosive characteristic in all parts of the Southern half of the Gharaziaoddin plain; but it has precipitin and corrosive characteristic in the North and Northwest of the Khoy plain.

Kalijar area is located in the North of Natanz in Isfahan Province. A number of igneous rocks have been occurred in two stages in this region. The first stage of volcanic rocks is include andesite bearing biotite, andesite bearing amphibole and green colour toffs (Eocene- Miopeliocene) and the second stage of plutonic rocks is include diorite, granodiorite bearing - hornblend and quartz monzonite (Oligo-Miocene) age in the area. The several alteration types have occurred in the area such as the sericitic, argillic and propylitic (chloritic and epidotic) that they are proximal to the fault units. The current alteration of index minerals are characterized by XRD analysis. Based on this approach, they are include calcite, quartz, alkali feldspar (Na-Ca), mica, hematite, dolomite and clay minerals. Geochemical exploration of stream sediments and heavy mineral methods were used to explore gold and copper mineralization in the area, which in the first stage 28 geochemical and 11 heavy mineral samples were taken and 68 geochemical and 18 heavy mineral samples in the second stage. The results which are gained by lab analysis by samples by ALS Chemex in Canada in ICPMS method to determine for rock forming and mineralizing minerals revealed the anomaly of Zn, As, W, Cu, Mo, Au, Ag, Pb elements in the area. The Spearman correlation coefficients has revealed the highest correlation between Fe,V(0.94), Pb,Zn (0.76), Mo,W(0.75), Cu,AS- (0.60) and W,Cr (0.81). Gold has shown the magximum correlation to Tungsten (0.54). Gold low correlation to the other metals, no correlation to rock forming minerals, represent the independent distribution of this element. Cu, Fe, Pb, Au have shown anomaly in heavy mineral studies. Nt-11, 35 ppm and Nt-12, 20 ppm of gold sampling have been harvested in this area, Two samples have been harvested from diorite mass borders (tuff rhyodacite unit) and andesite trachyte dyke to porphyrite, respectively. Geochemical anomaly maps indicates the highest gold concentration in south and the highest copper concentration in north. So they are possibly the best option for choosing the possible gold and copper mineralization. Gold mineralization to argillic alteration, copper mineralization to propylitic alteration had been shown on the basis of anomaly geochemical mineralization study. Gold and copper hydrothermal mineralization and their alteration association are related to hydrothermal solution in intrusive diorite mass (Upper Oligocene) age in northern area.

Micropaleontological study of the Asmari Formation is based on 58 thin sections obtained from a stratigraphical section in the northeastern flank of Anaran anticline (Southern Lorestan). In the studied section, the Asmari Formation has a thickness of 219 meters and mainly consists of limestone, argillaceous limestone, marl and anhydrite; it lies on the Pabdeh Formation and is overlain by the Gachsaran Formation. Two biozones (Aquitanian to Burdigalian: Early Miocene in age) were recognized: Assemblage Zone. Elphidium sp14., - Miogypsina sp and Assemblage Zone. Borelis melo group- Meandropsina iranica

The studied area is located in the sorth-west of Sirjan in Kerman Province. In geological classification of Iran it lies in the Sanandaj-Sirjan zone. The Gol-Gohar metamorphic complex which include marble, calc schist, quartz mica schist, amphibole schist and amphibolite is host rock for iron ore deposit. According to importance of formation condition host rock in ore deposit genesis, results of amphibolites petrographic and electron microprob studies, hornblende barometry (5.85-7.13 Kb), amphibole-plagioclase (682-728°C) and Tibiotite thermometry indicate that amphiboles are calcic and metamorphism of Gol-Gohar complex amphibolites probably occurred in upper part of amphibolite facies condition.