Petrology, geochemistry and tectonic setting intrusive massives of Baft ophiolitic – melange, Southeast of Kerman, Iran
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article
2013
eng
Baft ophiolitic – mélange belt is a part of the ophiolite melange belt of central Iran whose genesis is considered as an environment related to Tethys subduction at Upper Cretaceous. Major part of intrusive masses of Baft ophiolitic – melange form gabbros with the inequigranular texture fine to coarse and pegmatitic, plagiogranites also with inequigranular general texture have been developed within the isotropic gabbros as local small masses or vein and or these have been injected as relatively thick veins within the dolerite dikes. Plagiogranites are located mainly in the range of volcanic arc and syncollision, and gabbros are located in the range of calc alkaline arc basalts. Based on the REE distribution pattern normalized according to chondrite plagiogranites indicate relatively similar pattern with gradual changes in the concentration of REE that indicates these rocks is syngenetic. The LREE enrichment shows that granites are related to suprasubduction zone that originally has been formed from island arc tholeiitic series or calk–alkaline series. Relative enrichment with almost flat pattern especially in part HREE, can be related to the shallow depth of partial melting for magma production of these rocks and or participation of amphibole in their formation, therefore consideration of hornblende gabbro and or amphibolitic source rock seems more logical for at least plagiogranites that are specifically enriched in HREE. In gabbros also the REE pattern normalized based on chondrite follow trend almost flat along with an enrichment slight increase of LREE elements in comparison with HREE that is indicating similar origin of gabbroic samples. According to the existence of defined differences in the content and pattern of REE in most samples of plagiogranite and gabbros of Baft ophiolitic–mélange–acid phase derivation from the gabbros does not seem plausible at least in template of partial melting for most samples of plagiogranite. Since the content of REE in the Baft plagiogranites is not higher than gabbros and even in one of samples this amount is lower than gabbros level, therefore acid phase derivation is not also plausible for most samples in the template of fractionation process. However, due to the field interconnected part of plagiogranitic with the part of doleritic in Baft ophiolitic–mélange–it is possible that fractional crystallization of basic rocks doleritic that is accompanied with pyroxene and plagioclase separation be able to produce plagiogranitic magma with features of volcanic arc similar to that of what is seen in the Baft area
Quarterly Journal of Tethys
Payame Noor University
2476-7190
1
v.
3
no.
2013
164
176
https://jtethys.journals.pnu.ac.ir/article_2765_b4367d1a62d55b03490bddff59e8e068.pdf
Active tectonic analysis of Atrak river subbasin located in NE Iran (East Alborz)
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article
2013
eng
Study of tectonic affects in many fluvial systems shows that, rivers are valuable tools to active tectonics surveying. Study of stream channels and their associated deposits offset by faulting may reveal the amount displacement at particular site and give information that is critical for future earthquake hazards evaluation. Study area which is a subbasin of Atrak river is located at the NE Iran (East Alborz) and west of Bojnurd city. Aim of this research is separating high tectonic activity areas from low tectonic activity areas. In this research, in order to evaluate rate of tectonic activity the drainage basin asymmetry factor (Af), Transverse topographic symmetry factor (T), hypsometric integral (Hi) hypsometric curve (Hc), stream–gradient index (SL), valley floor width–valley height ratio (Vf) and Relative tectonic activity (Iat) were calculated. Based on Iat values, the study area was divided into four parts: Class 1 (very high relative tectonic activity: subbasin 2 and 3), class 2 (high relative tectonic activity: subbasin 4), class 3 (moderate relative tectonic activity: subbasin 5), class 4 (low relative tectonic activity: subbasin 1). Results of this research show that northern side of Qharajeh basin is inactive part of study area and southern side of Qharajeh basin is actives part.
Quarterly Journal of Tethys
Payame Noor University
2476-7190
1
v.
3
no.
2013
177
188
https://jtethys.journals.pnu.ac.ir/article_2766_90b229b7a52cedc7028c149602d07726.pdf
Investigation of Hydrogeochemical Characteristics and Groundwater Quality of Hoz–e–Soltan Lake, Qom, Iran
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article
2013
eng
In this research, the groundwater quality of Hoz–e–Soltan Lake and its catchment was studied for drinking, domestic and irrigation uses according to different parameters. This Lake with 195 km2 catchment area is located 85 km of southwest of Tehran–Qom highway. In order to investigate groundwater quality characteristics in the study area, 34 data from water of well belong to 2008 selected to processing and interpretation. The data was edited and processed to determine groundwater quality parameters such as Magnesium Absorption Ratio (MAR), Sodium Solution Percent (SSP), Residual Sodium Bicarbonate (RSBC), Permeability Index (PI), Kelly Ratio (KR) and Sodium Absorption Ratio (SAR), Electric Conductivity (EC), Na+, K+, Mg2+, Ca2+, SO42–, Cl–, HCO3–. Based on Piper diagram and cations and anions abundance order, the groundwater type of the study area is currently classified as Na+–Cl––SO42–. On the basis of Schoeller diagram, amounts of Na+, Cl–, SO42–, Total Hardness (TH) and Total Dissolved Solid (TDS) are higher than permissible limit and therefore, the water is unsuitable for drinking and domestic uses. The average pH values of the groundwater equal to 8, indicating alkaline nature of groundwater. Total hardness average of samples equal to 806.8, shows that the Hoz–e–Soltan groundwater was not suitable for drinking, domestic and irrigation uses. Sodium Content (Na %) average equal to 67.1, groundwater resources of the study area was belongs to the suspicious class. As a result, high salinity, SAR, TH, TDS, EC and Na% in most water samples have restricted the water quality for drinking, domestic and irrigation uses
Quarterly Journal of Tethys
Payame Noor University
2476-7190
1
v.
3
no.
2013
189
198
https://jtethys.journals.pnu.ac.ir/article_2767_ff4b6ad42a373fdf71be9610d61f9f51.pdf
Positioning underground reservoir by underground dams by using geoelectric method
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article
2013
eng
Today, saving and storing water are among the most critical and important issues which have attracted the world's attention. History of storing water in the form of ghanat and water reservoir by Iranians goes back to ancient times. Studies on this field show that benefiting from underground dams was one of the methods employed for exploiting water in past times. In countries like Iran, due to experiencing noticeable variations in groundwater levels during dry and wet seasons, this method has been considered beneficial for refining and storing water in dry seasons throughout the year. Following field studies and investigation of geological and geoelectrical properties of the region, this article presented the method of positioning the best site for constructing an underground dam and making an underground reservoir. In this paper, Watershed Koohzar Underground dam has been studied.
Quarterly Journal of Tethys
Payame Noor University
2476-7190
1
v.
3
no.
2013
199
204
https://jtethys.journals.pnu.ac.ir/article_2768_1e7f6926c4cdc339d7419cc3a9513d5e.pdf
Assessment of the effects of municipal wastewater on the heavy metal pollution of water and sediment in Arak Mighan Lake, Iran
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article
2013
eng
Heavy metal concentrations in surface water, wastewater and sediments collected from Mighan Lake in Markazi province, Iran were analyzed, and assessment contamination were evaluated according to the water and sediment quality guidelines. The results showed that the average concentrations of heavy metals in water were ranked as: Ni> Cr> Pb> Fe> Cu> Zn. In comparison with results the background values, the Mighan Lake was polluted by Ni, Cr, Pb and Fe, Most of metals might be mainly from industrial effluent and wastewater around the lake. In the sediments in the Mighan Lake, Fe, Ni, Pb and Cr showed a decreasing trend while Cu and Zn present an increasing trend. The increase of Cu and Zn might due to industrial activity around of Mighan Lake. The analysis of assessment contamination based on quality guidelines suggested that heavy metals in most water and sediments from the Mighan Lake had high toxicity, with Ni, Cr and Pb in water and moderate toxicity, with Zn and Cu in sediment being the highest priority pollutant.
Quarterly Journal of Tethys
Payame Noor University
2476-7190
1
v.
3
no.
2013
205
214
https://jtethys.journals.pnu.ac.ir/article_2769_5a1a1bc6617eb51c216ff38234d99364.pdf
Passive seismic survey on the Darquain oil field
text
article
2013
eng
In the form of passive seismic methods, broadband seismometers have been used in hydrocarbon exploration. The frequency bandwidth typically studied is in the range of 1–6 Hz. The observations on low frequency band of microtremors are used to calculate the spectral ratio of vertical and horizontal components (V/H) and Power Spectral Density (PSD). Attributes based on the V/H ratio and the PSD have been suggested as tools to identify hydrocarbon reservoir location. In this paper, earthquakes and background noise recorded by broadband seismometers are used. We used ambient noise data and a major earthquake data (Nurabad, Iran) that were recorded in a seismographic network with five broadband seismometer stations located at Darquain Oil Field in Khuzestan, Iran. At a station located on top of the reservoir we observe a prominent peak in both V/H and PSD attributes.
Quarterly Journal of Tethys
Payame Noor University
2476-7190
1
v.
3
no.
2013
215
224
https://jtethys.journals.pnu.ac.ir/article_2770_77f523c8e35884f24c750acbad0b9dda.pdf
Adakitic Volcanism in Sahand Region, Northwest Iran: Geochemical and Geodynamic Implications
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article
2013
eng
We present new whole major and trace elements data for a suite of adakitic dacite to rhyolite rocks from the Sahand region. These rocks formed in the Pliocene to Pleistocene during the the collision between the Arabian and Eurasian plates following subduction of Neo–Tethys Ocean. These subvolcanic intrusions were emplaced into late Cretaceous and Eocene sedimentary، volcano–clastic and volcanic rocks. Geochemical data indicate that the subalkaline dacitic to rhyodacitic rocks have an adakitic characteristics with Na2O/K2O (1.8–3.16), high Sr (391–804ppm), Mg# = (18–57) and low Y (3.6–20.8 ppm), low Yb (0.65–1.29 ppm), and low heavy rare earth element (HREE) abundances. Fractionated REE patterns with, (Ce/Yb)N = 10–27, absence of negative Eu anomalies, low content of Y, Nb, Ti, and high Sr/Y ratios (74–265) suggest that the source was likely hydrous garnet–amphibolite or eclogite, possibly generated during subduction of the Neo–Tethyan oceanic slab beneath the Central Iran microplate. The adakitic volcanism was followed by eruption of alkaline magmatism in this area. Slab melting occurred after cessation of subduction, possibility cause by the collision. Transtensional tectonics accompanied by a locally extensional stress regime is account for magma genesis and ascent.
Quarterly Journal of Tethys
Payame Noor University
2476-7190
1
v.
3
no.
2013
225
240
https://jtethys.journals.pnu.ac.ir/article_2771_42e45c2838850d10978acb5fe607f9f7.pdf