Mineralogy and mineral chemistry of alteration zone in order to determine the tectonic settings and mineralization characteristics in the Choreh-Nab iron deposit (Western Alborz)

Ebrahimi Fard, Hamed; Ghasemi Siani, Majid; Tabbakh Shabani, Amir Ali; Nazarian, Ma; Karimi Shahraki, Behrouz

doi:10.22034/KJES.2023.8.2.106631

Volume 8, Issue 2 (Autumn & Winter 2023) KJES 2023, 8(2): 164-211 | Back to browse issues page

‎ 10.22034/KJES.2023.8.2.106631

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Ebrahimi Fard H, Ghasemi Siani M, Tabbakh Shabani A A, Nazarian M, Karimi Shahraki B. Mineralogy and mineral chemistry of alteration zone in order to determine the tectonic settings and mineralization characteristics in the Choreh-Nab iron deposit (Western Alborz). KJES 2023; 8 (2) :164-211
URL: http://gnf.khu.ac.ir/article-1-2874-en.html

Mineralogy and mineral chemistry of alteration zone in order to determine the tectonic settings and mineralization characteristics in the Choreh-Nab iron deposit (Western Alborz)

Hamed Ebrahimi Fard¹

, Majid Ghasemi Siani ^*

², Amir Ali Tabbakh Shabani¹

, Ma Nazarian³

, Behrouz Karimi Shahraki

1- دانشکده علوم زمین
2- دانشکده علوم زمین , majed6239@gmail.com
3- پژوهشکده علوم زمین

Abstract: (528 Views)

The Chore-Nab iron deposit is located in the northwest of the Zanjan-Zaker district. The deposit was formed in quartz monzonite, syenogranite, and granodiorite bodies introded into Lower Cambrian volcanic (andesite) and sedimentary units (siltstone, tuff, and ignimbrite) in the Tarom-Hashtjin metallogenic province. Iron mineralization occurs as brecciated, massive, disseminated, and vein-veinlet types. Major alteration minerals include actinolite, albite, magnetite, epidote, phlogopite, k-feldspar, and biotite. The main sulfide minerals are pyrite, chalcopyrite, and bornite. Based on field and mineralogical studies, sodic-calcic, potassic, propylitic, sericitic, siliceous, and argillic alterations have been identified in the deposit. Sodic-calcic alteration (albite-actinolite-magnetite), characterized by massive and brecciated magnetite in the depth, calcic (actinolite) and potassic (secondary biotite) alteration in the middle levels associated with vein-veinlet sulfide mineralization and finally propylitic alteration (chlorite-epidote) in the shallow levels are observed. Based on the results of chemical analyses, the clinopyroxenes in the alteration zones (mainly sodic-calcic) are mostly augite and less commonly diopside. Plagioclase has a range of albite compositions. Amphiboles are calcic and often tremolite and magnesio-hornblende. Finally, the absence of Cl in the composition of the amphiboles of the Chore-Nab deposit and the presence of at least two Cl-rich amphiboles in all the IOCG deposits of the Carajas mineral province can be attributed to the lack of influence of replacement mechanisms generated by Cl-rich hydrothermal fluids during sodic-calcic alteration.

Keywords: Mineral chemistry, alteration zones, IOCG type mineralization, subduction zone, Chore-Nab iron deposit, Zanjan-Zaker district

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Type of Study: Original Research | Subject: Economic Geology
Received: 2022/12/25 | Accepted: 2023/02/7 | Published: 2023/03/17