Petrography and mineral chemistry of volcanic host rocks in the Dohneh Cu mineralization, NE Zanjan

Mohammadi, Masoumeh; Nabatian, Ghasem; Honarmand, Maryam; Ebrahimi, Mohammad; Haji Abolfath, Ali

Volume 7, Issue 2 (Autumn&Winter 2022) KJES 2022, 7(2): 225-249 | Back to browse issues page

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Mohammadi M, Nabatian G, Honarmand M, Ebrahimi M, Haji Abolfath A. Petrography and mineral chemistry of volcanic host rocks in the Dohneh Cu mineralization, NE Zanjan. KJES 2022; 7 (2) :225-249
URL: http://gnf.khu.ac.ir/article-1-2793-en.html

Petrography and mineral chemistry of volcanic host rocks in the Dohneh Cu mineralization, NE Zanjan

Masoumeh Mohammadi¹

, Ghasem Nabatian ^*

², Maryam Honarmand¹

, Mohammad Ebrahimi¹

, Ali Haji Abolfath¹

1- University of Zanjan
2- University of Zanjan , gh.nabatian@znu.ac.ir

Abstract: (926 Views)

Dohneh area is located in the northeast of Zanjan and in the Western Alborz-Azarbayjan zone along the Tarom subzone. The outcropped rock units in the Dohneh area include Eocene volcanic and volcano-sedimentary rocks (equivalent to the Karaj Formation) which consist of tuff units including lithic crystal tuff and crystal lithic tuff as well as basaltic lava flows (amygdaloidal basalt and porphyritic basalt). Rock forming minerals in the Dohneh basalts include plagioclase, pyroxene and olivine. The secondary minerals in the basalts are chlorite, zeolite, carbonate (calcite), epidote, serpentine and iron oxides. The opaque minerals and apatite are present as minor minerals. The data resulted from electron microprobe suggest that the pyroxene composition in the Dohneh basalts are as Ca-Mg-Fe bearing pyroxene (low Na) and mostly show diopside, augite and minor clinoenstatite compositions. The feldspar composition is labradorite and sanidine. Based on microprobe analyses on chlorites, their composition is Mg rich which are grouped as diabantite and pininite. Moreover, the clinochlore is also detected in this area by XRD analysis. The results obtained from the electron microprobe analysis on zeolites show that zeolites of Dohneh area are low-content to medium-content silica. Na bearing zeolite namely natrolite is also recognized by XRD analysis. The chemical composition of pyroxene from the Dohneh area suggests that these minerals crystallized in pressure lower than 5 Kbar from alkaline to sub-alkaline magmas in the back-arc and subduction related setting.

Keywords: Shoshonitic magma, Dohneh volcanic complex, Alborz- Azarbayjan zone, Tarom, Zanjan.

Full-Text [PDF 1962 kb] (329 Downloads)

Subject: Economic Geology
Received: 2021/12/18 | Accepted: 2022/06/26 | Published: 2022/10/25