Alteration and mass balance of igneous rocks in the Taktelar area, northwest of Zahedan, SE Iran

Document Type : Research Article

Authors

• Mohammad Boomeri ¹
• Aَtefeh Piri ²
• Abdolbaset Nohtanifar ³

¹ Professor, Department of Geology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran

² M.Sc., Department of Geology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran

³ Guest Lecturer, Department of Geology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran

10.22067/econg.2022.69941.1017

Abstract

The Taktelar area is located in 140 Km northwest of Zahedan city in the Sistan Suture Zone. In this area Eocene flysch-like rocks such as shale, siltstone and sandstone are intruded and extruded by Oligocene-Miocene plutonic, extrusive and sub-volcanic rocks. The igneous rocks are dacite, andesite, and diorite porphyry and are mainly altered. The mineralization in the Taktelar area occurs as dissemination and vein types in sub-volcanic and sedimentary rocks. The disseminated mineralization is characterized with wide formation of pyrite with or without Cu minerals and vein mineralization includes malachite, galena and Au-bearing silicic veins. The hydrothermal alterations are potassic, phyllic, tourmalinitic, argillic, silicic and propylitic. The result of mass change calculation shows enrichments of SiO₂ and depletion of other elements in phyllic alteration zone. In argillic alteration zone, contents of As, Mo, Zn, and Pb were enriched and other elements were depleted or were not changed. The alteration zones with quartz stockwork veins and enrichment of SiO₂ and K₂O have the most enrichment of Cu and Mo. The behavior of the elements in the propylitic alteration zone is different and generally increasing of the main elements is more significant. The ore-making elements have more enrichment in samples with silica veins so that the highest enrichment of copper and molybdenum occurs in rocks with higher SiO₂ and K₂O and quartz veins.  Generally, in most altered zones, contents of copper, molybdenum, lead, zinc and arsenic show enrichment and rare earth elements show depletion. Light rare earth elements show more depletion than heavy rare earth elements, indicating their more mobility in hydrothermal systems.
 
Introduction
Alteration is characterized by mineralogical, and textural changes in the wall-rocks through which hydrothermal fluids circulate. There are several types of hydrothermal alterations, depending on the nature of the circulated fluid and wall-rocks and physico-chemical conditions of the formation environment. Although, the alteration types have been mainly investigated in terms of their minerals, recently they have been also described for geochemical characteristics and mass changes (Maanijou et al., 2012, Siahcheshm et al., 2014; Derakhshani and Abdolzadeh, 2009). The main aim of this paper is to study mass change and enrichment and depletion of the different elements in altered rocks in the Taktelar area. In addition, mineralogy and geochemistry of the alteration types will be investigated.
 
Geology
The Taktelar area is located 40 Km northwest of Zahedan city in the Sistan Suture Zone. This zone is characterized by Cretaceous ophiolites of the Neo-Tethys Ocean and Cretaceous to Eocene flysch-like rocks that have been intruded by a range of calc-alkaline to shoshonitic igneous rocks of subduction, collision and post-collision settings (Camp and Griffis, 1982). In the Taktelar and adjacent area, Eocene flysch-like rocks such as shale, siltstone and sandstone are intruded and extruded by Oligocene-Miocene plutonic, sub-volcanic, volcanic and pyroclastic rocks. The Oligocene plutonic rocks are mainly related to shoshonitic syenitic and mozonitc rocks (Piri, 2018).
Sub-volcanic rocks occur as stock and dikes and are mainly post-collisional arc related, calc-alkaline dacite and diorite porphyry. The volcanic rocks range from basalt to dacite. The pyroclastic rocks are lithic tuff and ignimbrites. The volcanic, sub-volcanic and sedimentary rocks have been altered in the study area.  The study area has been affected by several faults including NW-SE and N-S strike-slip and NE and E-S faults.
 
Methods
Several samples were collected from outcrops and cores of all rocks and alteration types.  Thin, thin-polish and polish sections of the samples were studied by polarizing microscopes at the University of Sistan and Baluchestan in Zahedan, Iran.  Some of them were analyzed by XRF (9 samples) and ICP-MS and ICP-OES (12 samples) to measure main and trace elements, respectively. The mass change of these elements is calculated by the Grant (2005), MacLean and Kranidiotis (1987) and MacLean (1990) methods.
 
Result and discussion
The igneous rocks in the Taktelar are mainly andesite, dacite and diorite porphyry that mainly contain plagioclase, quartz, amphibole and biotite. Other igneous rocks in this area are monzonite and syenite that contain mainly plagioclase, orthoclase, clinopyroxene, amphibole and biotite. The flysch-type rocks are sandstone, siltstone and metamorphosed shales (hornfels). The sedimentary flysch-like rocks and stocks are extensively and intensively altered and weakly mineralized.  The mineralization occurs as dissemination and vein types. The alteration types are potassic, sericitic (phyllic), tourmalinitic, argillic, silicic and propylitic. The potassic alteration occurs in dioritic to granodioritic stocks in the north part of the Taktelar area and is characterized with orthoclase, biotite and quartz-pyrite stockworks and little malachite. The phyllic alteration including tourmalinitic and sericitic alteration as the most extensive alteration mainly occurs in dacite and is characterized with sericite, quartz, pyrite, tourmaline and clay minerals. The propylitic alteration occurs in dikes and sedimentary and igneous rocks mainly in marginal parts of the study area and is characterized with epidote, calcite, chlorite, quartz and pyrite. The argillic and silicic alterations are the most intensive and extensive alteration around silicic and mineralized veins in the Taktelar area. The mineralized veins are important for exploration of Au, Ag, Cu and Pb.
The Isocon and MacLean and Kranidiotis (1987) methods monitor composition-volume relations by the following equations:  C^A_i=M^O/M^A(C^O_i+ΔC_i) and DC_i=(C^A_i/C^O_i) of immobile element*C^A_i-C^O_i, respectively, where Ci is concentration of the species i, O and A refer to original and altered rocks, respectively, M^O and where M^A represents equivalent masses before and after alteration and Δ means change. The results show enrichments of Cu, Mo, Pb, Zn and As and depletion of REE in most alteration zones. The alteration zones with quartz stockwork veins and enrichment of SiO₂ and K₂O have the most enrichment of Cu and Mo.
 
Conclusion
Isocon diagrams and gain and lost histograms show that the main, minor and rare earth elements were mainly depleted while Cu, Mo, Pb, Zn, As were usually enriched during alteration by hydrothermal fluids. The most enrichment of Cu occurs in amphibole-biotite diorite porphyry that was cut by quartz stockworks. The SiO₂ and K₂O were increased in this type of rock that may be a character of potassic alteration. The most depleted alterations in the Taktelar area are phyllic and argillic alterations.

Keywords

• Subvolcanic rocks
• Au and Cu mineralization
• Alteration
• Mass balance
• Sistan suture zone

20.1001.1.20087306.1401.14.3.3.8

---

References

Aghanabati, A., 1991. Geological map of Daryacheh – ye – Hamun (1:250000) and Kuh-e-Seyasteragi (1:100000). Geological Survey of Iran.

Asadi, N., Emami, M.H. and Kheirkhah, M., 2010. Alteration characteristics of the Abtorsh Youzbashichai area and the analysis of geochemical behavior of elements (major and trace) in alteration environment. Petrology, 1(3): 11–28. (in Persian with English abstract) Retrieved October 10, 2022 from https://ijp.ui.ac.ir/article_16046_7d164169a713269e1b59679b48ee74ec.pdf

Babazadeh, S., Mazaheri, A., Raghimi, M. and Rahimi Chakdel, A., 2014. Mineralogy, geochemistry and mass changes due to alteration of Khosh Veylagh volcanic rocks, East of Golestan province. Iranian Journal of Crystallography and Mineralogy, 21(4): 607–624. (in Persian with English abstract) Retrieved October 10, 2022 from http://ijcm.ir/article-1-267-fa.html

Biabangard, H., Boomeri, M., Timouri, K. and Mohammadpour, F., 2017. Petrography, alteration and genesis of iron mineralization in Roshtkhar. Journal of Economic Geology, 9(1): 93–115. (in Persian with English abstract) https://doi.org/10.22067/ECONG.V9I1.47297

Boomeri, M., 2017. Porphyry deposits in Sistan suture zone, Sistan and Baluchestan province, southeast Iran. 9^th National Conference of Economic Geology Society of Iran, University of Birjand, Birjand, Iran.

Boomeri, M., Moradi, R., Stein, H. and Bagheri, S., 2019. Geology, Re-Os age, S and O isotopic composition of the Lar porphyry Cu-Mo deposit, southeast Iran. Ore Geology Reviews, 104(1): 477–494. https://doi.org/10.1016/j.oregeorev.2018.11.018

Boomeri, M., Piri. A., Nohtanifar, A. and Soloki, H., 2020. Copper and Gold mineralization and petrography and geochemistry of igneous rocks in Taktalar, northwest of Zahedan, Sistan and Baluchestan province.  Researches in Earth Sciences, 11(44): 109–128. (in Persian with English abstract) https://doi.org/10.52547/esrj.11.4.109

Camp, V.E. and Griffis, R.J., 1982. Character, genesis and tectonic setting of igneous rocks in the Sistan suture zone, eastern Iran. Lithos, 15(3): 221–239. https://doi.org/10.1016/0024-4937(82)90014-7

Derakhshani, R. and Abdolzadeh, M., 2009. Geochemistry, mineralization and alteration zones of Darrehzar porphyry copper deposit, Kerman. Journal of Applied Sciences, 9(9): 1628–1646. https://doi.org/10.3923/jas.2009.1628.1646

Esmaeili, D. and Afshuni, S.Z., 2009.  Investigation of mass changes of elements in hydrothermal alteration processes in Astaneh granitoid (southwest of Arak). Geoscience, 18(71): 97–104. (in Persian) https://doi.org/10.22071/gsj.2010.56996

Fulignati, P., Gioncada, A. and Sabranna, A.,1999. Rare earth element behaviour in the alteration facies of the active magmatic-hydrothermal systems of volcano. Journal of Volcanology and Geothermal Research, 88(4): 325–342. https://doi.org/10.1016/S0377-0273(98)00117-6

 

Ghofran Mola, G.J., 2018. Geochemical characteristics of altered and mineralized rocks in Taktalar exploration area, northwest of Zahedan. M.Sc. thesis, University of Sistan and Baluchestan, Zahedan, Iran, 209 pp. (in Persian with English abstract)

Grant, J.A., 1986. The Isocon diagram: A simple solution to Gresens’ equation for metasomatic alteration. Economic Geology, 81(8): 1976–1982. https://doi.org/10.2113/gsecongeo.81.8.1976

Grant, J.A, 2005. Isocon analysis: A brief review of the method and applications. Physics and Chemistry of the Earth, 30(17–18): 997–1004. https://doi.org/10.1016/j.pce.2004.11.003

Gresens, R.L., 1967. Composition-volume relationships of metasomatism. Chemical Geology 2: 47–65. https://doi.org/10.1016/0009-2541(67)90004-6

Guilbert, J.M. and Park, C.F., 1986. The Geology of Ore Deposits. Freeman and Company, New York, 905 pp.

Hattori, K.H. and Keith, J.D., 2001. Contribution of mafic melt to porphyry copper mineralization: evidence from Mount Pinatubo, Philippines, and Bingham Canyon, Utah, USA. Mineralium Deposita, 36(8): 799–80. https://doi.org/10.1007/s001260100209

Hedayati, N., 2015. Petrography and geochemistry of igneous rocks in Nakhilab, northwest of Zahedan with special view on origin of Au and Cu mineralization. M.Sc. thesis, University of Sistan and Baluchestan, Zahedan, Iran, 108 pp. (in Persian with English abstract)

Hedayati, N., Boomeri, M. and Biabangard, H., 2016. Petrography and geochemical characteristics of Nakhilab igneous complex, northwest of Zahedan. Petrology, 7(26): 23–44. (in Persian with English abstract) http://dx.doi.org/10.22108/ijp.2016.20840

Hezarkhani, A., 2002. Calculation of mass transfer and element mobility during the hydrothermal alteration in the Sungun porphyry copper deposit, Iran.  International Journal of Engineering Basics, Application and Aspects, 5(4): 391–408. Retrieved October 10, 2022 from https://www.ije.ir/article_71405_886c695fec0df2515fb2215538e9fa66.pdf 

Jamtveit, B. and Hervig, R., 1994. Constraints on transport and kinetics in hydrothermal systems from zoned garnet crystals. Science, 263(5146): 505–508.     Retrieved October 10, 2022 from https://www.jstor.org/stable/2883028

Janabadi, L., 2019. Identification, zoning and Formation of alteration types in the area of Copper Exploration, south of Zahedan, southeast of Iran. M.Sc. thesis, University of Sistan and Baluchestan, Zahedan, Iran, 135 pp. (in Persian with English abstract)

Khamar, F., 2017. Geological, geochemical, geophysical and drilling data modelling in Taktelar explorational area. M.Sc. thesis, University of Birjand, Birjand, Iran, 110 pp. (in Persian with English abstract)

Maanijou, M. and Mostaghimi, M., 2014. The mass balance calculation of hydrothermal alteration zones of Sarcheshmeh porphyry-Cu ore deposit. Journal of Economic Geology, 2(5): 175–199. (in Persian with English abstract) https://doi.org/10.22067/ECONG.V5I2.31718

Maanijou, M., Rasa, I., Lentz, D.R., 2008. Petrography and Alteration of Chehelkureh Copper Deposit: Mass Balance of Elements and Behavior of REE. Geosciences, 67: 86–101. (in Persian with English abstract) https://doi.org/10.22071/gsj.2009.57786

Maanijou, M., Rasa, I. and Lentz, D.R., 2012. Petrology, Geochemistry, and Stable Isotope Studies of the Chehelkureh Cu-Zn-Pb deposit, Zahedan. Economic Geology, 107(4): 683–712. https://doi.org/10.2113/econgeo.107.4.683

MacLean, W.H., 1990. Mass change calculations in altered rock series. Mineralium Deposita, 25(1): 44–49. https://doi.org/10.1007/BF03326382

MacLean, W.H. and Kranidiotis P., 1987. Immobile elements as monitors of mass transport in hydrothermal alteration: Phelps Dodge massive sulfide deposit, Matagami. Economic Geology, 82(4): 951–962. https://doi.org/10.2113/gsecongeo.82.4.951

Mathieu, L., 2018. Quantifying hydrothermal alteration: A Review of Methods. Geosciences, 8(7): 1–27.  https://doi.org/10.3390/geosciences8070245

Mikaili, R., Kalimi Noghreyan, M., Mackizadeh. M.A. and Taghipour B., 2011. Elements variations and the origin of fluids during the hydrothermal alterations in the Astaneh-Arak granitoid. Petrology, 2(7): 119–134. (in Persian with English abstract) Retrieved October 10, 2022 from https://ijp.ui.ac.ir/article_16082_89f4bdfe4e4b15dfd76ae4284d8312f0.pdf

Mohammadi, A., Burg, J.P., Bouilhol, P. and Ruh, J., 2016. U-Pb geochronology and geochemistry of Zahedan and Shah Kuh plutons, southeast Iran: implication for closure of the south Sistan suture zone: Lithos, 248–251: 293–308. https://doi.org/10.1016/j.lithos.2016.02.003

Mohammadzadeh, M.J., Mahboubi Aghdam. M. and Mohebbi, P., 2016. Detecting hydrothermal alteration zones by alteration box plot and mass change calculation using immobile elements in the Gezildash massive sulfide copper deposit of Khoy. Geoscience, 26(101): 231–244. (in Persian with English abstract) https://doi.org/10.22071/gsj.2016.41119

Nesbitt, H., 1979. Mobility and fractionation of rare earth elements during weathering of a granodiorite. Nature, 279(5710): 206–210. https://doi.org/10.1038/279206a0

Pang, K.N., Chung. S.L., Zarrinkoub, M.H., Khatib, M.M., Mohammadi, S.S., Chiu, H.Y., Chu, C.H., Lee, H.Y. and Lo, C.H., 2013. Eocene-Oligocene post-collisional magmatism in the Lut-Sistan region, eastern Iran: magma genesis and tectonic implications: Lithos, 180–181: 234–251. https://doi.org/10.1016/j.lithos.2013.05.009

Pirajno, F., 2009. Hydrothermal processes and mineral systems. Springer, Berlin, 1250 pp. http://dx.doi.org/10.1007/978-1-4020-8613-7

Piri, A., 2018. Mineralogy, alteration, and origin of copper mineralization in Taktalar, northwest of Zahedan. MSc thesis, University of Sistan and Baluchestan, Zahedan, Iran, 158 pp. (in Persian with English abstract)

Riebe, C.S., Kirchner, J.W. and Finkel, R., 2003. Long-term rates of chemical weathering and physical erosion from cosmogenic nuclides and geochemical mass balance. Geochimica et Cosmochimica Ac,ta 67(22): 4411–4427. https://doi.org/10.1016/S0016-7037(03)00382-X

Rollinson, H.R., 1993. Using geochemical data. evaluation, presentation, Longman, 352 pp.

Sargazi, S., Boomeri, M. and Marzi, M., 2015. Separation of altered zones in Kuh -e- Kallegar using processes of Satellite images of ASTER sensor, north of Zahedan, southeast of Iran. 7^th National Conference of Economic Geology Society of Iran, Damghan University, Damghan, Iran.

Siahcheshm, K., Karagari, A.A., Abedini, A. and Sindern, S., 2014. Elemental mobility and mass changes during alteration in the Maher-Abad porphyry Cu–Au deposit, SW Birjand, Eastern Iran. Periodico di Mineralogia, 83(1): 55–76.  https://doi.org/10.2451/2014PM0004

Stocklin, J., 1968. Structural History and Tectonics of Iran. A review: American Association of Petroleum Geologists Bulletin, 52(7): 1229-1258. https://doi.org/10.1306/5D25C4A5-16C1-11D7-8645000102C1865D

Tirrul, R., Bell, L.R., Griffis, R.J. and Camp, V.E., 1983. The Sistan suture zone of eastern Iran. Geological Society of America Bulletin, 94(1): 134–150. http://dx.doi.org/10.1130/0016-7606(1983)94<134:TSSZOE>2.0.CO;2

Valeh, N. and Saidi, A., 1989. Gelogical map of Chehelkureh (1:100000). Geological Survey of Iran.

Warren, I., Simmons, S.F. and Mauk, J.L., 2007. Whole-Rock Geochemical Techniques for Evaluating Hydrothermal Alteration, Mass Changes, and Compositional Gradients Associated with Epithermal Au-Ag Mineralization. Economic Geology, 102(5): 923–948. https://doi.org/10.2113/gsecongeo.102.5.923

Whitney, D.L. and Evans, B.W., 2010. Abbreviation for name of rock-forming minerals. American Mineralogist, 95(1): 185–187. https://doi.org/10.2138/am.2010.3371