Economic Geology
Amir Pakizeh; Fardin mousivand; Abdorrahman Rajabi; Sajjad Maghfouri
Abstract
The Nohkuhi copper deposit located at 40 Km Northwest of Kerman, occurred in the Central Iran structural zone (Bafq- Posht-e- Badam block), within Late Precambrian-Early Cambrian volcano-sedimentary sequences. Host sequence of mineralization consists of dominantly black shale, sandstone and dacitic lava ...
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The Nohkuhi copper deposit located at 40 Km Northwest of Kerman, occurred in the Central Iran structural zone (Bafq- Posht-e- Badam block), within Late Precambrian-Early Cambrian volcano-sedimentary sequences. Host sequence of mineralization consists of dominantly black shale, sandstone and dacitic lava of Rizu Series. Mineralization occurred as stratabound (vein-veinlets) and stratiform (bedded) in the three copper- and two iron-manganese horizons. The mineralization in the Nohkuhi area involves four ore facieses including stringer, vent complex, bedded, and hydrothermal-exhalative banded iron and manganese-rich sediments. This mineralization contains primary pyrite, chalcopyrite, sphalerite, hematite and pyrolusite. Wallrock alterations are dominated by chloritic and carbonatic-sericitic- silicic. Metal zonation was observed in the deposit. Based on characteristics of mineralization, such as tectonic setting, host rocks, ore textures and structures, mineralogy, metal and alteration zonation, and comparison with main characters of the volcanogenic massive sulfide (VMS) deposits, the mineralization shows most similarities with the siliciclastic felsic or Bathurst- type deposits.
Economic Geology
Fardin mousivand; Fayeq Hashemi; Mehdi Rezaei-Kahkhaei; Amir Pakizeh
Abstract
The Darreh Amrood Pb (Ag) deposit is located in south of Ghohrood, in the Urumieh-Dokhtar magmatic arc (UDMA). Host rockes to the deposit are Middle to Late Eocene grey-green siliceous tuff and crystal lithic tuff. Geometry of orebodies is stratabound, irregular, and semiconcordant to discordant to layering ...
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The Darreh Amrood Pb (Ag) deposit is located in south of Ghohrood, in the Urumieh-Dokhtar magmatic arc (UDMA). Host rockes to the deposit are Middle to Late Eocene grey-green siliceous tuff and crystal lithic tuff. Geometry of orebodies is stratabound, irregular, and semiconcordant to discordant to layering of the host rocks. Ore structures and textures are dominated by semi-massive to brecciated, banded and vein-veinlets. Main primary minerals are galena, pyrite and chalcopyrite, and secondary minerals are dominated by covelline, goethite and hematite. Gangue minerals are epidote, chlorite, sericite, clay minerals, quartz, calcite and barite. Wall rock alterations are dominated by epidote-chlorite and sericitic. The rare earth element (REE) pattern of ores is not similar to that of volcanic rocks in the footwall and hangingwall that is concordant with sub-seafloor replacement process for ore formation. Also Ce showed negative anomaly that can be attributed to Ce in the seawater. Also based on structural, stratigraphic, petrographic, textures, mineralogical, alteration and geochemical studies, it is inferred that the Pb (Ag) mineralization in the Darreh Amrood area occurred as bimodal felsic- or Kuroko-type volcanogenic massive sulfide (VMS) mineralization, and formed as sub-seafloor replacement. It should be noted that the Darreh Amrood deposit is the first recognition of base metal-rich and poor barite VMS mineralization in the UDMA.
S Maghfouri; E Rastad; F Mousivand
S Maghfouri; E Rastad; F Mousivand; Y Lin
Abstract
Copper mineralization in Nudeh Cu deposit and Frezy, Garab, Kalateh lala (Nieran) and Chun occurrences, located in southwest of Sabzevar hosted by a Upper Cretaceous volcano-sedimentary sequence formed in a rift environment. The main is host rock of the Nudeh Cu sulfide deposit includes alkali olivine ...
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Copper mineralization in Nudeh Cu deposit and Frezy, Garab, Kalateh lala (Nieran) and Chun occurrences, located in southwest of Sabzevar hosted by a Upper Cretaceous volcano-sedimentary sequence formed in a rift environment. The main is host rock of the Nudeh Cu sulfide deposit includes alkali olivine basalt flow and subordinate tuffaceous silty sandstone. Host rock of the Ferizy and Garab occurrences is andesite flow. The rock forming mineral of Kalateh lala (Nieran) and Chun occurrences is tuffaceous silty sandstone. Sulfide mineralization in the Nudeh deposit and occurrences within an Upper Cretaceous volcano-sedimentary sequence occurs as sheet-like &tabular shape within three ore horizons. Based on nature of sulfide mineralization, mineralogy and textures of sulfide minerals, the Nudeh deposit can be divided into three different ore facies. Based on their situation towards the vent of mineralizing fluid, these facies include: A) Vein-veinlets facies (Stringer zone) includes sulfide veins and silica that form as a scissors of host rocks under the massive ore facies. Vein-veinlets and replacement textures formed main features of this facies. B) Massive ore facies that forms the thicker part of generally massive higher grade ores in west of the deposit and includes sulfide mineralization with heterogeneous nature and stratabound, limited in the alkali olivine basalt flow. C) Bedded ore facies which is thinner than the massive ore facies and is characterized by layered and banded apparent and low grade ore. The rock forming mineral of this facies is tuffaceous silty sandstone. This facies occurs as laminated and banded sulfides contemporaneous with the host rocks layering at eastern part of the deposit. Mineralogy of Nudeh deposit includes chalcopyrite, pyrite, bornite, sphalerite, boulangerite and magnetite wall rock alterations are dominated by silicification, chloritization, sericitization and epidotization. The most important characteristics of mineralization at the Nudeh deposit such as tectonic setting, host rocks, mineralogy, metal content as well as wall rock alterations, show similarities with volcanogenic massive sulfide (VMS) deposits. Accordingly, Nudeh Cu deposit is regarded as a Besshi - or pelitic mafic VMS deposit.
F. Mousivand; E. Rastad; M. H. Emami; J. M. Peter; M. Solomon
Abstract
Zn-Pb-Cu mineralization in the Chahgaz area, located 60 km south of Shahre Babak, occurs within a Middle Jurassic metamorphosed bimodal volcano-sedimentary sequence in the South Sanandaj-Sirjan zone. Mineralization occurs associated with exhalites within units 1and 2 of the host sequence as numerous ...
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Zn-Pb-Cu mineralization in the Chahgaz area, located 60 km south of Shahre Babak, occurs within a Middle Jurassic metamorphosed bimodal volcano-sedimentary sequence in the South Sanandaj-Sirjan zone. Mineralization occurs associated with exhalites within units 1and 2 of the host sequence as numerous occurrences, and within unit 3 as Chahgaz deposit and some occurrences hosted by meta-rhyolitic tuff, meta-rhyolite, and meta-pelites, as predominantly stratiform, tabular and sheeted-like orebodies at specific stratigraphic horizons. Ore textures include massive, semi-massive, banded, laminated, disseminated and vein-veinlets. Ore minerals are predominantly pyrite, sphalerite, galena, chalcopyrite, tetrahedrite, arsenopyrite, and minor bornite and pyrrhotite, and gangue minerals include dominantly sericite, quartz, chlorite and barite. Wallrock alteration is dominated by sericitic and chloritic and minor carbonatic and silicic types. Altered host rocks have been foliated due to metamorphism and deformation, and along with the associated ores have been folded and faulted and show cataclastic, triple junctions, pressure shadows, crenulations, and boudinage features. Based on geological, mineralogical, geochemical and alteration studies, it is inferred that Zn-Pb-Cu mineralization in the Chahgaz area has occurred as volcanogenic massive sulfide (VMS)-type in an arc rift basin, and has subsequently been metamorphosed under greenschist facies conditions during the Late Cimmerian and Laramid orogenies and younger events. This mineralization, in comparison with similar deposits in the world, has the most similarities with those deposits of siliciclastic felsic-type in the Bathurst Mining Camp, Canada, and Iberian Pyrite Belt in Spain and Portugal; and it is the first recognition of this type in Iran.