Kamran Motevali; Mehrdad Behzadi; Mohammad Yazdi
Abstract
Eocene magmatism with intermediate-acid tuffs and volcanic rocks, the host to the Nodoushan deposit in Yazd province, intruded by Oligocene early diorite and later granite plutonic rocks. The former involved in iron skarn (containing epidote and euhedral grossularite) to the north and northern part of ...
Read More
Eocene magmatism with intermediate-acid tuffs and volcanic rocks, the host to the Nodoushan deposit in Yazd province, intruded by Oligocene early diorite and later granite plutonic rocks. The former involved in iron skarn (containing epidote and euhedral grossularite) to the north and northern part of the deposit, the latter contributed to fault-controlled Zn-Pb deposit. The structural features controlled both the mineralization and consequent alterations which ranged from silicification (central) to argillic (northern). Propylitic alteration and dolomitization considered the minor ones, the iron contamination of which could be provided by earlier iron mineralization. Sulfide minerals dominantly pyrite, sphalerite and galena followed by chalcopyrite and late stage copper minerals such as covellite, digenite, bornite, chalcocite. Oxide minerals developed to the depth of 40m as a result of faults. Sphalerite which is of high-Fe type was characterized by extensive chalcopyrite disease, the iron content of which provided by earlier iron concentration. The concentration of chalcopyrite exsolution along sphalerite margins as well as galena veinlets is due to the thermal shock of later stage hydrothermal fluids that deposited galena and chalcopyrite. Negligible fossil replacements indicate both mineralization and alteration. It was concluded that the Zn-dominant mineralization was deposited under the structural controlling faults which reflects part of its earlier iron mineralization.
S Ghaderi; E Rastad; N Rashidnejad-Omran; M Mohajjel
Abstract
Tungsten (Cu-Au-Zn) deposits and occurrences in Iran can be divided into two separate categories based on their genesis, tectonic setting, mineral paragenesis and related processes inherent in their formation. The first category contains deposits, which are located in metamorphosed Late Triassic-Middle ...
Read More
Tungsten (Cu-Au-Zn) deposits and occurrences in Iran can be divided into two separate categories based on their genesis, tectonic setting, mineral paragenesis and related processes inherent in their formation. The first category contains deposits, which are located in metamorphosed Late Triassic-Middle Jurassic volcano-sedimentary sequences, and their distribution is indicated by layering. These deposits are located in a specific stratigraphic position and are concentrated in contact of volcanic units with carbonate rocks. The geodynamic setting of this category probably is intracontinental rifting. The second category contains deposits located in metamorphosed sedimentary rocks of the Shemshak group and Jurassic granitoids. These deposits have vein-veinlet geometry and their formation is controlled by faults, fractures and shear zones. The geodynamic setting of this category probably is active continental margins. The mineral paragenesis of the first group generally contains scheelite and Cu-Fe-Zn sulfides, whereas the paragenesis of the second group is wolframite, scheelite, chalcopyrite, arsenopyrite, with gold and specifically bismuth.
M. Abdi; Majid Ghaderi; N. Rashidnejad-Omran; A. Najafi
Abstract
Two cases of tungsten-copper vein-type mineralization have been studied in the Nezam-abad and Deh-hossein areas, in southwest of Shazand. The hydrothermal quartz-tourmaline mineralized veins have different host rocks (biotitic-granite and meta-sandstone). Considering similar ore metals (tungsten-copper-tin-lead-zinc) ...
Read More
Two cases of tungsten-copper vein-type mineralization have been studied in the Nezam-abad and Deh-hossein areas, in southwest of Shazand. The hydrothermal quartz-tourmaline mineralized veins have different host rocks (biotitic-granite and meta-sandstone). Considering similar ore metals (tungsten-copper-tin-lead-zinc) in the Nezam-abad and Deh-hossein areas, same mineralogy of veins (quartz-dravite) and similar REE variation patterns in the two areas, it is suggested that the Nezam-abad and Deh-hossein mineralized veins have the same origin. It means, when the Br-bearing fluids were active, they caused the quartz-tourmaline vein-type mineralization in this area. Considering the barren intrusions in the area and other mineralogical-geochemical evidences in this study, it could be concluded that tungsten and other metallic elements in the Nezam-abad and Deh-hossein ore-bearing veins have a sedimentary/metamorphic origin.
