Tectonics
Mojtaba Ershadinia; Farzin Ghaemi; Massoud Homam
Abstract
The Fariman complex is located in the northeast of Iran and southeast of Mashhad, contains a variety of rocks from the Permian to the present era that have undergone several stages of deformation. In this paper, the structural geometry of faults and folds of the region is analyzed and based on it, the ...
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The Fariman complex is located in the northeast of Iran and southeast of Mashhad, contains a variety of rocks from the Permian to the present era that have undergone several stages of deformation. In this paper, the structural geometry of faults and folds of the region is analyzed and based on it, the deformation stages of Fariman complex are identified, which indicates its evolution during 3 stages of deformation. In the first stage of deformation, tectonic forces along with the thermal stage have caused the transformation of sediments and the formation of first generation foliation and folds in the region. First-generation thrusts also formed during this phase, thrusting Palaeotethys remnants. The second stage of deformation has led to the formation of the second generation of thrusts and folds in the region. Kinematic analysis of second generation thrusts indicates two reverse motion phases with leftlateral strike-slip component and right–lateral strike–slip with reverse component.Its reverse motions, which result in the formation of misplaced massive carbonate associated with the second stage of deformation, and its dextral motion, which cut and displace previous structures and affect all rock units in the region, the third stage of deformation is analyzed.
Petrology
Abdolsamad pourmohammad; Ahmad Ahmadi khalaji; Masoud Homam; Zahra Tahmasbi; Mohammad Ebrahimi
Abstract
Geysour area is located in the east of Gonabad city and is part of the north of the Lut Block. The rocks in this area include granitoid rocks and high temperature – low pressure metamorphic rocks. Granitoid rocks are composed of granodiorite, enclave (metamorphic and igneous) and microgranites. ...
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Geysour area is located in the east of Gonabad city and is part of the north of the Lut Block. The rocks in this area include granitoid rocks and high temperature – low pressure metamorphic rocks. Granitoid rocks are composed of granodiorite, enclave (metamorphic and igneous) and microgranites. These rocks belong to medium to high potassium calc-alkaline series, low temperature I type granite and are poorly peraluminous. The Chondrite-normalized REE patterns show that the rocks are enriched incompatible elements, with negative anomalies in Nb, Ta, Sr, P, Ti and Ba and strong enrichment in Rb, K and Th. These patterns are in perfect harmony in granodiorite, microgranular enclave (MME) and microgranite specimens. This harmony also has in upper, middle continental crust and greywackes. Positive anomalies in Rb, Th, Sm and negative anomalies in Ba are prominent in the composition of the crust. Based on the integration of these patterns with the pattern of upper continental crust (UCC) elements and greywackes and adaptation to laboratory work, the Geysour granitoid originated from crustal materials and a little mantle component. The temperature of granitoid formation was estimated based on the Zircon saturation temperature of 748-790 ֯C. Microgranular enclaves have rounded and oval shapes, mixed areole around them, fine grained texture, quartz and plagioclase eyes, bladed biotite, needled apatite, oxide phases in biotite, and the presence of a simple mixed – hyperbolic curve between MME and granodiorite. Field, petrography and geochemistry of the major and rare earth elements data suggest mixing/ mingling (partial melting) processes for the origin of enclaves and the rare earth elements patterns indicates the relationship between Geysour granitoid with the subduction system. Analysing its data, based on logarithmic ratios, show collision tectonic environment. Also, the tectonic-chemical distinctive diagrams suggest a syn-collision to post-collision tectonic type that is interpreted in connection with the collision of the Afghan Block with the Lut Block.
Kh. Ebrahimi; p. Roohbakhsh; S. M. Homam; H. Abbasnia
Abstract
Dahaneh Qaleh exploration prospect is located about 300 km southwest of Mashhad and 50 km northwest of Bardeskan. The exploration prospect is also a part of Taknar massive sulfide mineralization zone and lithology of the area consists of chlorite sericite schist, biotite sericite schist and sericite ...
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Dahaneh Qaleh exploration prospect is located about 300 km southwest of Mashhad and 50 km northwest of Bardeskan. The exploration prospect is also a part of Taknar massive sulfide mineralization zone and lithology of the area consists of chlorite sericite schist, biotite sericite schist and sericite schist with metamorphosed basic and intermediate igneous rocks in the type range from meta-gabbro diorite to meta-diorite that they belong to Taknar Formation.Taknar Formation was intrusived by low grade metamorphosed intermediate subvolcanic intrusive rocks with porphyry texture in the type range of meta-hornblende-quartz monzonite porphyry, meta-hornblende-quartz monzodiorite porphyry, meta-hornblende monzodiorite porphyry, meta-quartz monzonite porphyry and meta-hornblende-quartz monzosyenite porphyry. All of the geological unites are affected by moderate to severe alteration and sulfide minerals including pyrite, were transformed to secondary iron oxides due to oxidation. Before the field investigation, ETM+ and ASTER sensors data were processed with "color composition of band ratios", "standard and selective principal component analysis" methods and finally "spectral angle mapping" as a successful method for more accurate separation of altered minerals that introduced Hematitic, Chloritic, Epidotic, Sericitic and Silicification alteration zones in the study area. Accuracy of the processes were proved by the following field, petrography and mineralography studies.
