Determination of physicochemical conditions of causative intrusion in the Masjeddaghi Cu-Au porphyry-epithermal deposit: constraints on chemical composition of biotite

Document Type : Research Article

Authors

• Shohreh Hassanpour ¹
• Zohreh Rahnama ²
• Susan Ebrahimi ³

¹ Associate Professor, Department of Geology, Payame Noor University, Tehran, Iran

² Ph.D., Department of Earth Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran

³ Assistant Professor, Department of Mineral Exploration, Faculty of Mining Engineering, Petroleum and Geophysics, Shahrood University of Technology, Shahrood, Iran

10.22067/econg.2023.79377.1056

Abstract

The Masjeddaghi porphyry-epithermal Cu-Au deposit has located in the western part of the Alborz-Azarbaijan zone; in the south margin of Lesser Caucasus. The Eocene porphyritic quartz diorite intrusion has intruded into the andesite volcanic rocks and formed the main host rock of Cu-Au mineralization. Hydrothermal alteration types consisted dominantly of potassic, phyllic, argillic, and propylitic, and local silicification around the veins. Electron microprobe studies indicated that the Masjeddaghi biotites has been located in the phlogopite field and fall into the field of re-equilibrated primary biotite. Moreover, these biotites indicate the tectonomagmatic setting and magma characteristics related to calk-alkaline granitoids which were originated from mantle sources. The temperature of biotites from Masjeddaghi indicated a range between 417 ºC -641ºC. The conditions of oxygen fugacity in the magmatic biotites are in the range of hematite-magnetite (HM) and nickel-nickel oxide (NNO), which indicate high oxygen fugacity of the magma in this ore deposit. In the Masjeddaghi biotites, there is no linear/parallel trend between halogen fugacity,d log (ƒH₂O/ƒHF), log (ƒH₂O/ƒHCl) and log (ƒHF/ƒHCl) lines. Therefore, it is possible that biotites have not formed under the same conditions and were in equilibrium in a wide range of temperatures and compositions with hydrothermal fluids.
 
Introduction
The Masjeddaghi porphyry-epithermal Cu-Au deposit is located in the margin of the Arasbaran Belt, in the Alborz-Azarbaijan structural zone in the NW of Iran. The host rock of mineralization is diorite porphyry, which has been intruded into the andesitic volcanic rocks. Paleocene andesitic and lavas crop out in the southeastern and eastern parts of the area. Paleocene andesitic rocks, including lavas, dikes, pyroclastic, and epiclastic rocks overlying on the Permian-Triassic rocks. The mineralized host rocks composed of the dioritic stocks that have formed the main mass of Masjeddaghi and is dated at 54 Ma (Hassanpour and Alirezaei, 2017). The Middle Eocene diorite porphyry includes granular to porphyry texture and with some dikes extending with east - west trend in the northern and eastern parts of the Masjeddaghi district. It is called the main Masjeddaghi Porphyry. This magmatic sequence and associated Cu-Mo-Au mineralization and alterations have been dated at about 54 Ma (Hassanpour and Alirezaei, 2017).
The hydrothermal alteration types consist dominantly of potassic, phyllic, argillic, propylitic and locally of silicification around the veins (Ebrahimi et al., 2021; Hassanpour and Alirezaei, 2017; Ebrahimi et al., 2017). The chemical composition of biotite is sensitive to chemical and physical factors which are related to magmatic and hydrothermal activities such as halogens (e.g., F and Cl) and metals compositions, elemental distributions, water concentrations, temperature and pressure. Geological and geochemical features of porphyry-epithermal Cu-Au Masjeddaghi ore deposit have been studied in detail by Ebrahimi et al., 2021; Hassanpour and Alirezaei, 2017; Ebrahimi et al., 2017. In this research study we attempt to characterize the physicochemical attributes of causative magma in the Masjeddaghi porphyry ore deposit, by using biotite mineral chemistry.
 
Material and methods
All samples are from the least altered diorite intrusion and from potassic alteration zone were collected from the surface and drill cores (up to 700m) in the Masjeddaghi area. More than 150 thin and thin-polished sections were studied and subsequently, four samples were selected for EMPA (Electron Micro-Probe Analyses) analysis. Twenty-six points of biotite grains were selected and analyzed by using a Cameca SX-100 instrument in czechoslovakia (central European laboratory). The analyses were conducted with 15 kV accelerating voltage and 10 nA beam current. The results were processed by using the MICA⁺ software. 
(Yavuz, 2003).
 
Results
On the basis of petrographic studies, diorite porphyry consists of plagioclase, hornblende, biotite and quartz minerals. Biotite phynocrysts are within fine grained matrix and biotite chemistry can be used as an important indicator to evaluate magma crystallization condition (Selby and Nesbitt, 2000). Three kinds of biotites have been recognized in the samples: magmatic, re-equilibrated and hydrothermal type. On the basis of Mg, (Mn+Fe²⁺) vs. (Al^VI+Fe³⁺+Ti), Fe²⁺/(Fe²⁺+Mg) vs. Al^{IV and} (Mg-Li) vs. Fe_T + Mn + Ti-Al^VI) diagrams all plotted in the phlogopite field. The samples in the MgO-10×(TiO₂) -(FeO+MnO) diagram fall into the field of re-equilibrated primary biotite (Nachit et al., 2005). The temperature of biotites in diorite samples varies between 417-522 ºC (Bean, 1974) and 516-641 ºC (Henry et al., 2005).
 
Discussion
Biotites in the Masjeddaghi Cu-Au porphyries are mainly Plogopite and are dominantly from the samples taken from potassic alteration zone and situated in the re-equilibrated biotites field. The ore deposit tectonically is related to the calk-alkaline magma. Generally, biotites are calk-alkaline, with high content of MgO and reducedAl₂O₃ which refers to Al and Mg replacements in an ochtahedral setting. This ore deposit has a Magnesium rich calk-alkaline magma. The oxygen fugacity of biotites is in the range of hematite-magnetite (HM) and nickel-nickel oxide (NNO), which indicates high oxygen fugacity of the magma in this ore deposit. In the Masjeddaghi biotites, there is no linear/parallel trend between halogen fugacity and log (ƒH₂O/ƒHF), log (ƒH₂O/ƒHCl) and log (ƒHF/ƒHCl) lines. Therefore, it is possible that biotites have not formed under the same conditions and were in equilibrium in a wide range of temperatures and compositions with hydrothermal fluids. Halogen ratios of the Masjeddaghi biotites with other porphyry deposits in the world show similarity with Bingham and Santa Rita ore deposits. Moreover, these biotites indicate the calk-alkaline signature and mantle source for the magma.

Keywords

• Biotite
• Physicochemical condition
• Copper-Gold porphyry
• Masjeddaghi
• Iran

---

References

Abdel-Rahman, A.M., 1994. Nature ofbiotites from alkaline, calc-alkaline, and peraluminous magmas. Journal of Petrology, 35 (2): 525–541. http://doi.org/10.1093/PETROLOGY/35.2.525

Afshooni, S.Z., Mirnejad, H., Esmaeily, D. and Haroni, H.A., 2013. Mineral chemistry of hydrothermal biotite from the Kahang porphyry copper deposit (NE Isfahan), Central Province of Iran. Ore Geology Review 54: 214–232. https://doi.org/10.1016/j.oregeorev.2013.04.004

Ayati, F., Yavuz, F., Noghreyan, M., Asadi Haroni, H., Yavuz, R., 2008. Chemical characteristics and composition of hydrothermal biotite from the Dalli porphyry copper prospect, Arak, central province of Iran. Mineral. Petrol 94: 107–122. https://doi.org/10.1007/s00710-008-0006-5

Beane, R.E., 1974. Biotite stability in the porphyry copper environment. Economic Geology, 69(2): 241–256. https://doi.org/10.2113/gsecongeo.69.2.241

Bineli Betsi, T. and Lentz, D.R., 2012. Chemical composition of rock-forming minerals in granitoids associated with Au–Bi–Cu, Cu–Mo, and Au–Ag mineralization at the Freegold Mountain, Yukon, Canada: magmatic and hydrothermal fluid chemistry and petrogenetic implications. International Geology Review, 55(6): 657–691. https://doi.org/10.1080/00206814.2012.731767

Boomeri, M., Nakashima, K. and Lentz, D.R., 2010. The Sarcheshmeh porphyry copper deposit, Kerman, Iran: A mineralogical analysis of the igneous rocks and alteration zones including halogen element systematics related to Cu mineralization processes. Ore Geology Reviews, 38(4): 367–38. https://doi.org/10.1016/j.oregeorev.2010.09.001

Ebrahimi, S., Alirezaei, S., Pan, Y. and Mohammadi, B., 2017. Geology, mineralogy and ore fluid characteristics of the Masjeddaghi gold bearing veins system, NW Iran. Journal of Economic Geology, 9(2): 561-586 (in Persian with English abstract). https://doi.org/10.22067/econg.v9i2.51493

Ebrahimi, S., Pan, Y. and Rezaeian, M., 2021. Origin and evolution of the Masjeddaghi Cu-Au-Mo porphyry and gold epithermal vein system, NW Iran: Constraints from fluid inclusions and sulfur isotope studies. Mineralogy and Petrology, 115: 643–66. https://doi.org/10.1007/s00710-021-00761-z

Foster, M.D., 1960. Interpretation of the composition of trioctahedral micas. United States Geological Survey Professional Paper, 354(B–2):11–49. https://pubs.usgs.gov/pp/0354b/report.pdf

 Hassanpour, Sh. and Alirezaei, S., 2017. Eocene Masjed-Daghi porphyry Cu-Au deposit; an example of island arc porphyry type deposit in NW Iran.  Scientific Quarterly Journal of Geosciences, 26(104): 43–58. (in Persian with English abstract). https://doi.org/10.22071/gsj.2017.50166

Heidari, M., Zarasvandi, A., Rezaei, M., Raith, J. and Adel Saki, A., 2019. Physicochemical attributes of parental magma in collisional porphyry copper systems; using biotite chemistry, case study: Chahfiruzeh porphyry copper deposit. Journal of Economic Geology, 10(2): 561–586. (in Persian with English abstract) https://doi.org/10.22067/econg.v10i2.65652 

Henry, D.J., Guidotti, C.V. and Thomson, J.A., 2005. The Ti-saturation surface for low-to medium pressure meta pelitic biotites: Implications for geothermometry and Tisubstitution mechanisms. American Mineralogist, 90(2–3): 316–328. https://doi.org/10.2138/am.2005.1498

Imamalipour, A., Abdoli Eslami, H. and Hajalilou, B., 2011. Geochemistry of hydrothermal alterations associated with epithermal gold mineralization in Masjeddaghi area, east of Jolfa, NW Iran. Journal of Economic Geology, 2(2): 199–215. (in Persian with English abstract) https://doi.org/10.22067/ECONG.V2I2.7851

Jacobs, D.C. and Parry, W.T., 1979. Geochemistry of biotite in the Santa Rita Porphyry copper deposit, New Mexico. Economic Geology, 74(4): 860–887. https://doi.org/10.2113/gsecongeo.74.4.860

Loferski, P.J. and Ayuso, R.A., 1995. Petrography and mineral chemistry of the composite Deboullie pluton, northern Maine, USA: Implications for the genesis of Cu-Mo mineralization. Chemical Geology, 123(1–4): 89–105. https://doi.org/10.1016/0009-2541(95)00040-S

Moshefi, P., Hosseinzadeh, M.R., Moayyed, M. and Lentz, D.R., 2018. Comparative Study of Mineral Chemistry of Four Biotite Types as Geochemical Indicators of Mineralized and Barren Intrusions in the Sungun Porphyry Cu -Mo Deposit, Northwestern Iran. Ore Geology Review, 97: 1–20. http:/doi.org/10.1016/j.oregeorev.2018.05.003

Munoz, J.L., 1984. F-OH and Cl-OH exchange in micas with applications to hydrothermal ore deposits. Reviews in Mineralogy and Geochemistry. 13(1): 469–494. https://doi.org/10.1515/9781501508820-015

Nabavi, H., 1976. An introduction to the geology of Iran. Geological Survey of Iran, Tehran, 109 pp. (in Persian)

Nachit, H., Ibhi, A.B., Abia, El-H., El Hassan, A. and Ben Ohoud, M., 2005. Discrimination between primary magmatic biotites, reequilibrated biotites, and neoformed biotites. Comptes Rendus Geoscience, 337(16): 1415–1420. https://doi.org/10.1016/j.crte.2005.09.002

NICICO (National Iranian copper industries Co.), 2006. Final geological studies on Masjeddaghi, Unpublished interior report.

Parkinson, I.J. and Arculus, R.J., 1999. The redox state of subduction zones: insights from arc peridotites. Chemical Geology, 160(4): 409–423. https://doi.org/10.1016/S0009-2541(99)00110-2

Parry, W.T., Ballantyne, G.H. and Wilson, J.C., 1978. Chemistry of biotite and apatite from a vesicular quartz latite porphyry plug at Bingham, Utah. Economic Geology, 73(7): 1308–1314. https://doi.org/10.2113/gsecongeo.73.7.1308

Parsapoor, A., Khalili, M., Tepley, F. and Maghami, M., 2015. Mineral chemistry and isotopic composition of magmatic, reequilibrated and hydrothermal biotites from Darreh-Zar porphyry copper deposit, Kerman (Southeast of Iran). Ore Geology Reviews, 66: 200–218. https://doi.org/10.1016/j.oregeorev.2014.10.015

Pourkaseb, H., Zarasvandi, A. and Saed, M., 2017. Magmatic-hydrothermal fluid evolution of the Dalli porphyry Cu-Au deposit; using Amphibole and Plagioclas mineral chemistry. Journal of Economic Geology, 93(1): 73–92. https://doi.org/10.22067/econg.v9i1.51704

Pourmohammad, A.S., Ahmadi Khalaji, A., Homam, M., Tahmasebi, Z. and Ebrahimi, M., 2020. Geochemistry, petrogenesis and tectonic setting of Geysour granitoid, East Gonabad. Scientific Quarterly Journal, Geosciences, 29(115): 137–150. (in Persian with English abstract) https://doi.org/10.22071/gsj.2019.148243.1533

Rieder, M., Cavazzini, G., Yakonov, Y.D., Frank-Kanetskii, V.A., Gottardi, G., Guggenheim, S., Koval, P.W., Müller, G., Neiva, A.M.R., Radoslovich, E.W., Robert, J.L., Sassi, F.P., Takeda, H., Weiss, Z. and Wones, D.R., 1998. Nomenclature of the micas. Clays and Clay Minerals, 36‌(3): 905–912. https://doi.org/10.1346/CCMN.1998.0460513

Selby, D. and Nesbitt, B.E., 2000. Chemical composition of biotite from Casino Porphyry Cu–Au–Mo mineralization, Yukon, Canada: evaluation of magmatic and hydrothermal fluid chemistry. Chemical Geology, 171(1–2): 77–93. https://doi.org/10.1016/S0009-2541(00)00248-5

Siahcheshm, K., Calagari, A.A., Abedini, A. and Lentz, D.R., 2012. Halogen signatures of biotites from the Maher-Abad porphyry copper deposit, Iran: characterization of volatiles in syn-to post-magmatic hydrothermal fluids. International Geology Review, 54(12): 1353–1368. https://doi.org/10.1080/00206814.2011.639487

Sillitoe, R.H., 2010. Porphyry copper systems. Economic Geology, 105(1): 3–41. https://doi.org/10.2113/gsecongeo.105.1.3

Taghavi, A., Maanijou, M., Lentz, D.R., Sepahi-Greow, A.A., Maruoka, T., Fujisaki, W. and Suzuki, K., 2022. Biotite compositions and geochemistry of porphyry-related systems from the central Urumieh Dokhtar Magmatic Belt, western Yazd, Iran: Insights into mineralization potential. Lithos, 412–413: 106593. https://doi.org/10.1016/j.lithos.2022.106593

Tischendorf, G., Gottesmann, B., Förster, H.J. and Trumbull, R.B., 1997. On Li-bearing micas: Estimating Li from electron microprobe analyses and an improved diagram for graphical representation. Mineralogical Magazine, 61(409): 809–834. https://doi.org/10.1180/minmag.1997.061.409.05

Yavuz, F., 2003. Evaluating micas in petrologic and metallogenic aspect: I—definitions and structure of the computer program Mica+. Computational Geosciences, 29(10): 1203–1213. https://doi.org/10.1016/S0098-3004(03)00142-0

Zaheri–Abdehvand, N., Hassanpour, S., Rassa, I. and Rajabpour, S., 2022. Silicates chemistry as indicators of physicochemical and geothermometry conditions on porphyry ore system: A case study of the Haftcheshmeh Cu–Mo deposit, NW Iran. Ore Geology Reviews, 142: 104716. https://doi.org/10.1016/j.oregeorev.2022.104716

Zhang, W., Lentz, D.R., Thorne, K.G. and McFarlane, C., 2016. Geochemical characteristics of biotite from felsic intrusive rocks around the Sisson Brook W–Mo–Cu deposit, west central New Brunswick: An indicator of halogen and oxygen fugacity of magmatic systems. Ore Geology Reviews, 77: 82–96. https://doi.org/10.1016/j.oregeorev.2016.02.004

Zhu, C. and Sverjensky, D.A., 1992. F–Cl–OH partitioning between biotite and apatite: Geochemica Cosmochimical Acta, 56(9): 3435–3467. https://doi.org/10.1016/0016-7037(92)90390-5