Economic Geology
Sholeh Malekshahi; Masoumeh Khalajmasoumi; Hadi Mohammad- Doost; Mona Sojdehee; Shahrzad Aboutorab
Abstract
The Sarkuh Porphyry Copper deposit is located about 6 km southwest of Sarcheshmeh porphyry copper deposit. Alterations in the region include advanced potassic, propylitic, phyllic and argillic. Copper mineralization is mainly associated with porphyry granodiorite mass. Minerals include chalcopyrite, ...
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The Sarkuh Porphyry Copper deposit is located about 6 km southwest of Sarcheshmeh porphyry copper deposit. Alterations in the region include advanced potassic, propylitic, phyllic and argillic. Copper mineralization is mainly associated with porphyry granodiorite mass. Minerals include chalcopyrite, pyrite, magnetite and some molybdenite. Fluid inclusion studies were performed on quartz from the sulfide viens of the potassic fraction and showed that the main mineralization phase was present with a homogenization temperature between 250 and 527 ° C, salinity between 13.6 and 52.9 wt٪ NaCl, has a high salinity in Sarkuh deposit (Orthomagmatic phase and hypogene mineralization). The homogenization temperature in the late stages of the receding phase (convective phase and the influence of atmospheric waters in the hydrothermal cycle) is around 132 to 165 degrees Celsius and its salinity is 0.005 to 4.74% equivalent to the weight of NaCl. The observed salinity variation can be attributed to the boiling event. The investigation of sulfur isotope composition on pyrite and chalcopyrite minerals in Sarkoh deposit was between +1 and 2.7‰, which indicates the magmatic source of sulfur. The stable oxygen isotope data on quartz veins, show positive range between 7.6 to +9.3‰ with an average of +8.5, indicates a magmatic source for hydrothermal fluids. Also, due to the limited range of sulfur isotopic composition, it can be concluded that the isotopic composition of sulfur has not undergone changes or contamination by other sources of sulfur, or the mixing of magmatic fluid with other sources has been very insignificant. Isotopic thermometry shows the temperature of 315°C and 476°C for the pair of pyrite-chalcopyrite minerals.
Economic Geology
Behzad Hajalilou; M. Razmara; Nasim Hajalilou
Abstract
The placer ore deposit of Ataeieh is located in south west of Mashhad and central Iranian microplate. The petrography and mineralography studies of VTM placer ore deposit, showed that the main ores in this area from high to low amounts are: magnetite, titanomagnetite, hematite and ilmenite. It revealed ...
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The placer ore deposit of Ataeieh is located in south west of Mashhad and central Iranian microplate. The petrography and mineralography studies of VTM placer ore deposit, showed that the main ores in this area from high to low amounts are: magnetite, titanomagnetite, hematite and ilmenite. It revealed that the ultramafic and gabbros are the main source for opak minerals by mineralography Studies. The SEM-EDS, EPMA and XRM studies on the placer ore deposit and their origion presentaded remarkable results. The SEM investigation showed that, in the magma crystallization the solid soulution is formed between titanomagnetite and ilmenite at 800°C and then with the decreasing of temperature up to 600°C the ilmenite and magnetite exsolution lamella segreqates and separated from titanomagnetite phase either the ophiolite sequence is the source of this deposit. Titaniumand Vanadium enter to the ilmenite and titanomagnetite in gabbroic rocks whit continuing of magma crystallization. The EPMA analysis on gabbroic units showed that these rocks are origion for Ti and V in placers.
M Bahrammanesh Tehrani
Abstract
In this research, the brachiopod fauna from the Tournaisian (Early Carboniferous) Mobarak Formation located in the EasternAlborzMountains, North Iran have been analyzed. 745 specimens have been collected from the Abrendan section, located in north of the DamghanTown. The specimens classified into 36 ...
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In this research, the brachiopod fauna from the Tournaisian (Early Carboniferous) Mobarak Formation located in the EasternAlborzMountains, North Iran have been analyzed. 745 specimens have been collected from the Abrendan section, located in north of the DamghanTown. The specimens classified into 36 species of 27 genera and 5 undetermined species and genera of 5 subfamilies in 8 orders: Leptagonia analoga (Phillips, 1836), Delepineineae gen et sp. Ind., Geniculifera sp. Ind., Dictyoclostinae gen et sp. Ind., Geniculifera sp. Ind., Buxtonia sp. Ind., Marginatia vaughani (Muir-Wood, 1928), Marginatia sp. Ind., Tomiproductus elegantulus (Tolmatchoff, 1924), Tolmatchoffini gen. Et. Sp. Ind., Pustula cf. P. Altaica Tolmatchoff, 1924, Pustula cf. P. Kondomensis Sarytcheva, 1963, Pustula spp., Schellwienlla sp. A, Derbyiidae gen. Et sp. Ind., Rhipidomella michelini (Léveillé, 1835), Rhipidomella sp. A, Rhipidomella sp. B, Schizophoria (Schizophoria) resupinata (Martin, 1809),?Ptychomaletoechia sp. Ind.,Hemiplethorhynchus crassus Gaetani, 1968, Rossirhynchus adamantinus Gaetani, 1964, Paraphorhynchus aff. P. Elongatum Weller, 1905, Athyris sp. Ind., Cleiothyridina kusbassica Beznosova in Sarytcheva et al., 1963, Gerankalasiella sp. Ind., Composita megala (Tolmatchoff, 1924), Composita subquadrata (Hall, 1858a), Densalvus sp. Ind., Martinia sp. Ind., Ectochoristites sp. Ind., Prospirinae gen. Et. Sp. Ind., Athylopherous sp. Ind., Paralellora sp. Ind., Unispirifer (Unispirifer) striatoconvolutus (Benson & Dun in Benson, Dun & Browne, 1920), Unispirifer(Unispirifer) sp. A, Unispirifer (Unispirifer) sp. B, Imbrexia sp. Ind., Fusella sp. Ind., Syringothyris carteri (Hall, 1857), Syringothyris skinderi Sokloskaja, 1963 in Sarytcheva et al., 1963, Pseudosyrinx sp. Ind. A species of Molusca Rostrochonca, Hippocardia alborza Hoare & Aghababalou, 2001 has been also found. The quantitative biostratigraphic analysis of the brachiopod assemblages bed by bed collected along the Abrendan section allowed the recognition of three concurrent range biozones: the Schizophoria (S.) resupinata-Pseudosyrinx sp. Ind. Biozone, the Composita subquadrata-Geniculifera sp. Ind. Biozone, and the Cleiothyridina kusbassica-Unispirifer (U.) striatoconvolutus biozone. Most of the brachiopod taxa in the biozones range from the Tournaisian to the Visean. However, some are restricted to the Tournaisian, confirming the age suggested by foraminifers in the upper part of the formation. The statistical and paleogeographical analysis show that the North Iran Brachiopods are mostly close to the coeval faunas from N America and Russia. This confirms the presence of an equatorial current flowing southeastward along the Gondwanan margin.
A Hosseinkhani; F Molasalehi
Abstract
Ahangaran is an active Pb-Ag mine of Iran that is located in Malayer town, Hamedan province and situated in the Esfahan-Malayer Pb-Zn Metallogenic Zone. The mineralographical studies of different parts of the Ahangaran mine show different sulfide-oxide zones with major minerals including ...
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Ahangaran is an active Pb-Ag mine of Iran that is located in Malayer town, Hamedan province and situated in the Esfahan-Malayer Pb-Zn Metallogenic Zone. The mineralographical studies of different parts of the Ahangaran mine show different sulfide-oxide zones with major minerals including galena, cerussite, chalcopyrite, magnetite, pyrite, hematite, goethite and others minor minerals. For the first time, the minor minerals including jordanite-lengenbachite series, coronadite and galena molybdate is identified as a host for Pb and Ag using scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). Freibergite (Fahlore group) and lanaite as two minor minerals containing Ag are reported as major element in the crystalline lattice, as well. In addition to Ag presence in the minor minerals, it is measured up to 500 ppm in galena and cerussite by EPMA studies. Pb isotope study on a galena sample from Ahangaran deposit shows the Pb is radiogenic with orogenic reservoir characteristics in which high amount of Pb originated from the upper and lower crust. In addition, Pb model age shows Pb derivation from Triassic basement (249 Ma), and Pb isotopic ratios suggest a mature arc environment for the Ahangaran deposit.
M. Hosseini-Barzi; M. Houshyar; H. Ghalavand
Abstract
Field study, calcimetery and petrography of thin sections from Gurpi type section and petrography of cuttings from Ziloee oil field (well No. 5 and well No. 8) represent two carbonate members and two hybrid (mostly marl and in a few samples clay marl) members in these deposits. Microfacies analysis of ...
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Field study, calcimetery and petrography of thin sections from Gurpi type section and petrography of cuttings from Ziloee oil field (well No. 5 and well No. 8) represent two carbonate members and two hybrid (mostly marl and in a few samples clay marl) members in these deposits. Microfacies analysis of the carbonate members implies 2 microfacies belong to open sea of a carbonate ramp model. Moreover, authigenic glauconite and phosphate and framboidal pyrite propose deposition of these sediments in an anoxic condition. XRD and SEM analysis of marl members provide existence of illite and chlorite as clay minerals by certain detrital source and smectite by digenetic and probability detrial source in the upper marl member and existence of quartz in lower member. Coexistence of these minerals proposes a temperate climate during deposition of the upper marl member. Semi-quantitative analysis of XRD data represents descending trend for relative amounts of illite and ascending trend for smectite during deposition of upper marl member of Gurpi Formation which implies deepening of the sedimentary basin and relative climate warming. The digenetic processes in these deep marine deposits are limited to cementation, illitization, hematization and fracturing. Moreover, studying SEM images evident autogenetic origin of smectite in two samples from upper cretaceous (under K/T boundary) which can form during fluid exchange with mafic minerals and/or detrial clay minerals such as detrial smectite, illite. The absence of digenetic smectite in two samples from Paleocene (over K/T boundary) can be related to change in basin condition in Zagros basin, this period of time. Also, studying relative abundance of K and Th in NGS logs of well number 8 in Ziloee oil field shows that clay minerals in this formation are illite and montmorillonite.
M. Hosseini-Barzi; R. Alinejad-Kurdi; H. Ghalavand
Abstract
The calcimeteric analysis of samples from Pabdeh Formation, in type section (north of Dezful embayment subzone), represent a marl and shaly marl lithology. SEM images from these samples represent chlorite flakes with diagenetic origin (transformation of illite to chlorite) and imply the possible existence ...
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The calcimeteric analysis of samples from Pabdeh Formation, in type section (north of Dezful embayment subzone), represent a marl and shaly marl lithology. SEM images from these samples represent chlorite flakes with diagenetic origin (transformation of illite to chlorite) and imply the possible existence of other detrital clay minerals (include chlorite). However, XRD analysis of selected samples indicates the existence of montmorillonite, illite and chlorite showing a descending trend for clay percent and montmorillonite and ascending one for illite and chlorite from bottom to top of these deposits. Based on these evidences, we introduced the possibility for cooling in climate condition and shoaling in depth of deposition, from bottom to top of the Pabdeh Formation.
Study of Th, K & Th/K peaks of NGS log represents the existence of montmorillonite and illite, as common clay mineral. Calculating clay mineral percent, shale percent and uranium trend imply an anomaly at the uppermost part of the Pabdeh Formation which could be related to fault activity in Central Dezful embayment subzone and sediment supply probably due to Pyrrenean orogeny.
Therefore, investigation of clay mineral represent difference in sedimentary framework between northern Dezful embayment subzone and central Dezful embayment subzone and their different response to change in geological condition.
