Adakitic post-Miocene magmatism of Qaraie sub-volcanic dome, Mahneshan area (west of Zanjan)

Document Type : Research Article

Authors

• Sajad Moseni Badalabadi ¹
• Mir Ali Asghar Mokhtari ²
• Hossein Kouhestani ²

¹ M.Sc., Department of Geology, Faculty of Science, University of Zanjan, Zanjan, Iran

² Associate Professor, Department of Geology, Faculty of Science, University of Zanjan, Zanjan, Iran

10.22067/econg.2024.84571.1086

Abstract

Qaraie sub-volcanic dome in the west of Zanjan is part of the Urumieh-Dokhtar magmatic arc in the Central Iran zone. Qaraie dome with columnar joints was intruded into the Upper Red Formation sequence and Kahrizbeik granitoid intrusion with Upper Proterozoic age. Based on petrographical studies, this dome is composed of dacite-rhyodacite and consists of plagioclase, biotite, quartz, as well as occasionally hornblende and sanidine phenocrysts within the fine-grained groundmass. These rocks have a porphyritic texture and present vesicular plus flow textures. On the petrological diagrams, rock units of the Qaraie dome have dacite, rhyodacite, and trachy-dacite composition and indicate high-K calc-alkaline to shoshonitic nature. Based on primitive mantle normalized spider diagrams, samples of the Qaraie dome indicate positive anomalies of LILEs (Rb, Ba, Th, U, K, and Cs) along with negative anomalies of HFSEs (Nb, P, and Ti) together with distinctive positive anomaly of Pb. Chondrite-normalized REE patterns demonstrate LREE enrichment and a high ratio of LREE/HREE. Samples from the Qaraie dome demonstrate geochemical similarity with adakites and are classified as high-silica adakites. These rocks resulted from 25% partial melting of the Lower continental crust with garnet-amphibolite composition in a post-collisional setting.
 
Introduction
Neogene to Quaternary magmatism in NW of Iran occurred as sub-volcanic and volcanic acidic domes with an adakitic nature. Recent studies on Miocene and post-Miocene magmatic rocks from different parts of Iran have demonstrated that most of the dacitic-rhyodacitic rocks have an adakitic nature (Jahangiri, 2008; Jamshidi et al., 2015; Saadat, 2023). There are some small dacitic domes in the west of Zanjan (from the Qaraie village in the south to the Moghanlou village in the north) that have not been reported in published maps and geological reports. The Qaraie dacitic dome, the largest dome in this area, was marked as Kahrizbeik granitic intrusion in the Mahneshan 1:100000 geological map (Lotfi, 2001). Considering the importance of the Miocene-Pliocene sub-volcanic domes in the evolution of Iran's tectonic-magmatic settings, and their role in the formation of some Au-As mineralizations (e.g., Arabshah, Zarshouran, and Aghdareh in the Takab area; Najafzadeh et al., 2017), studying the Qaraie sub-volcanic dome can provide valuable information for this part of Iran.
 
Regional Geology
Based on Iranian tectono-stratigraphic zones, the Qaraie area is located in the Urumieh-Dokhtar magmatic belt within the Central Iran zone. This area is a small part of the Mahneshan 1:100000 geological map (Lotfi, 2001). Based on the prepared 1:25000 geological map for this study, the Qaraie area is composed of Cretaceous sedimentary rocks along with other rock units including the Lower Red Formation, Qom Formation and Upper Red Formation, and Pliocene conglomerate. Kahrizbeik granitoid with Upper Proterozoic age (Lotfi, 2001) is located in the central part of the area. The Qaraie sub-volcanic dome is exposed in the north of the Qaraie village. This sub-volcanic dome intruded into rock units of the Lower Red Formation and Kahrizbeik granitoid intrusion and revealed prismatic structure in marginal parts. There are some outcrops of dacitic sub-volcanic domes in the south of the Moghanlou village intruding into the limestones of the Qom Formation which had an important role in the formation of the Moghanlou Sb deposit (Bavi et al., 2023)
 
Materials and methods
This research includes field and laboratory studies. During the fieldwork, different rock units were identified and a geological map with a scale of 1:25,000 was prepared. In this base, 32 samples were collected from the Qaraie dome. Among the mentioned samples, 15 thin sections were examined using a transmitted polarized light microscope in the laboratory of the University of Zanjan. The chemical composition of rock samples (n = 15) was analyzed at the Zarazma Analytical Laboratories, Tehran, Iran using XRF and ICP–MS methods.
 
Results
Considering petrographical studies, the Qaraie dome compositionally includes dacite and rhyodacite. These rocks have porphyry along with glomeroporphyritic, vesicular, and flow textures. Dacites consist of plagioclase, biotite, quartz, and sometimes hornblende phenocrysts in the fine-grained groundmass. Sanidine presents along with the mentioned phenocrysts in rhyodacites.
Based on geochemical diagrams, Qaraie samples were classified as dacite, rhyodacite, and trachydacite. These rocks have a high-K calc-alkaline to shoshonitic affinity. Based on primitive mantle normalized spider diagrams, these rocks have similar patterns. These diagrams indicate positive anomalies of LILEs along with negative anomalies of HFSEs. Chondrite-normalized REE patterns demonstrate a steep slope pattern with LREE enrichment and a high ratio of LREE/HREE, devoid of specified positive and negative Eu anomaly (Eu/Eu* between 0.94-1.07), (La/Yb)_N and (La/Sm)_N ratio between 26.72-32.83 and 10.7-11.6, respectively.
Dacite-rhyodacites of the Qaraie dome demonstrate geochemical similarity with adakites and are platted in adakite field on Y vs. Sr/Y, La/Yb vs. Sr/Y, and SiO₂ vs. MgO diagrams. Based on Sr vs. CaO+Na₂O and Sr vs. Na₂O+K₂O diagrams, the Qaraie samples are classified as high-silica adakites.
 
Discussion and conclusion
Geochemical data including LILEs and LREEs enrichment and negative anomalies of HFSEs along with strong positive Pb anomaly demonstrate subduction-related magmatism for the Qaraie sub-volcanic dome. Based on tectonic-magmatic setting discrimination diagrams (Th vs. Ta, Th/Hf vs. Ta/Hf, Th/Ta vs. Yb, and Th/Yb vs. Ta/Yb diagrams), formation of the Qaraie dome has been related to an active continental margin tectonic setting. Based on the (La/Yb)_N vs. Yb_N diagram, the Qaraie adakitic dome resulted from 25% partial melting of garnet-amphibolite. Other diagrams such as SiO₂ vs. Ni indicate that the source rocks for the Qaraie adakitic dome resulted from a thick lower continental crust. Considering the Th vs. Th/Ce diagram, the Qaraie adakitic dome was formed in a post-collisional setting.
 
Acknowledgment
This research study was made possible by a grant from the office of the vice-chancellor of research and technology, University of Zanjan. We hereby acknowledge their generous support. The Journal of Economic Geology reviewers and editor are also thanked for their constructive comments.

Keywords

• Geochemistry
• Petrology
• Sub-volcanic dome
• Adakite
• Qaraie
• Orumieh-Dokhtar
• Zanjan

---

References

Amaral, W.D.S., Santos, T.J.S. and Wernik, E., 2011. Occurrence and geochemistry of meta-mafic rocks from the Forquilha Eclogite zone central Ceara (NE Brazil): geodynamic implications. Geological Journal, 46(2–3): 135–137. https://doi.org/10.1002/gj.1224

Bavi, M.H., Kouhestani, H. and Mokhtari, M.A.A., 2023. Genesis of the Moghanlou Sb deposit (west of Zanjan): Evidence from geology, mineralization, geochemistry, and fluid inclusions. Advanced Applied Geology, 13(1): 40–71.  (in Persian with extended English abstract) https://doi.org/10.22055/aag.2022.40141.2282

Bonin, B., 2004. Do coeval mafic and felsic magmas in post-collisional to within plate regimes necessarily imply two contrasting, mantle and crustal, sources? A review. Lithos, 78(1–2): 1–24. https://doi.org/10.1016/j.lithos.2004.04.042

Boynton, W.V., 1984. Cosmochemistry of the rare earth elements: Meteorite studies, In: P. Henderson (Editor), Rare Earth Element Geochemistry, Elsevier, 63–114. Retrieved January 15, 2024 from https://www.sciencedirect.com/science/article/pii/B9780444421487500083

Cameron, B.I., Walker, J.A., Carr, M.J., Patino, L.C., Matias, O. and Feigenson, M.D., 2003. Flux versus decompression melting at stratovolcanoes in southeastern Guatemala. Journal of Volcanology and Geothermal Research, 119(1-4): 21–50. https://doi.org/10.1016/S0377-0273(02)00304-9

Defant, M.J. and Drummond, M.S., 1990. Derivation of some modern arc magmas by melting of young subducted lithosphere. Nature, 347(10): 662–665. https://doi.org/10.1038/347662a0

Fazelvalipour, M.E., 2021. Petrography, geochemistry and petrogenesis of high-silica accccccc rocks from Bayram Abad area in the northwest Neyshabour (Northeast of Iran). Petrological Journal, 45(1): 113–134. (in Persian with Enblish abstract) https://doi.org/10.22108/ijp.2021.124930.1200

Foley, S. and Peccerillo, A., 1992. Potassic and ultrapotassic magmas and their origin. Lithos, 28(3-6): 181–185. https://doi.org/10.1016/0024-4937(92)90005-J

Foley, S.F. and Wheler, G.E., 1990. Parallels in the origin of the geochemical signature of island arc volcanic rocks and continental potassic igneous rocks: The role of titanites. Chemical Geology, 85(1-2): 1–18. https://doi.org/10.1016/0009-2541(90)90120-V

Gorton, M.P. and Schandle, E.S., 2002. From continental to island arc: A geochemical index of the tectonic setting for arc-related and within plate felsic to intermediate volcanic rocks. The Canadian Mineralogist, 38(5): 1065–1073. https://doi.org/10.2113/gscanmin.38.5.1065

Hastie, A.R., Kerr, A.C., McDonald, I., Mitchell, S.F., Pearce, J.A., Millar, I.L., Barfod, D. and Mark, D.F., 2010. Geochronology, geochemistry, and petrogenesis of rhyodacite lavas in eastern Jamaica: A new adakite subgroup analogous to early Archaean continental crust? Chemical Geology, 276(3–4): 344-359. https://doi.org/10.1016/j.chemgeo.2010.07.002

Hastie, A.R., Kerr, A.C., Pearce, J.A. and Mitchell, S.F., 2007. Classification of Altered Volcanic Island Arc Rocks using Immobile Trace Elements: Development of the Th-Co Discrimination Diagram. Journal of Petrology, 48(12): 2341–2357. https://doi.org/10.1093/petrology/egm062

Heidari, S.M., Ghaderi, M. and Kouhestani, H., 2017. Sediment-hosted epithermal gold mineralization at Arabshah, SE Takab, NW Iran. Geosciences Scientific Quarterly Journal, 27(105): 262–285. (in Persian with extended English abstract)  https://doi.org/10.22071/gsj.2017.53971

Irvine, T.N. and Baragar, W.R.A., 1971. A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Science, 8(5): 523–276.  https://doi.org/10.1139/e71-055

Jahangiri, A., 2008. Post-collisional Miocene adakitic volcanism in NW Iran: geochemical and geodynamic implications. Journal of Asian Earth Sciences, 30(3–4): 433–447. https://doi.org/10.1016/j.jseaes.2006.11.008

Jamshidi, Kh., Ghasemi, H., Troll, V.R., Sadeghian, M. and Dahren, B., 2015. Magma storage and plumbing of adakite-type post-ophiolite intrusions in the Sabzevar ophiolitic zone, NE Iran. Journal of Solid Earth, 6(1): 49–72. https://doi:10.5194/se-6-49-2015

Jiang, Y.H., Liu, Z., Jia, R.Y., Liao, S.Y., Zhou, Q. and Zhao, P., 2012. Miocene potassic granite-syenite association in western Tibetan Plateau: Implications for shoshonitic and high Ba-Sr granite genesis. Lithos, 134–135(3): 146–162. http://dx.doi.org/10.1016/j.lithos.2011.12.012

Kamber, B.S., Ewart, A., Collerson, K.D., Bruce, M.C. and McDonald, G.D., 2002. Fluid-mobile trace element constraints on the role of slab melting and implications for Archaean crustal growth models. Contributions to Mineralogy and Petrology, 144(10): 38–56. https://doi.org/10.1007/s00410-002-0374-5

Koepke, J., Schoenborn, S., Oelze, M., Wittmann, H., Feig, S.T., Hellebrand, E., Boudier, F. and Schoenberg, R., 2009. Petrogenesis of crustal wehrlites in the Oman ophiolite: Experiments and natural rocks. Geochemistry, Geophysics, Geosystems, 10(10): 1–26. https://doi.org/10.1029/2009GC002488

Le Bas, M.J., Le Maitre, R.W., Strecheisen, A. and Zanttin, B., 1986. A chemical of volcanic rocks classification based on the total alkali-silica diagram. Journal of Petrology, 27(3): 745–750. https://doi.org/10.1093/petrology/27.3.745

Lotfi, M., 2001. Geological Map of Mahneshan, scale1:100000. Geological Survey of Iran.

Machado, A.T., Chemale, J.F., Conceicao, R.V., Kawaskita, K., Morata, D., Oteiza, O. and Schmus, W.R.V., 2005. Modeling of subduction components in the Genesis of the Meso-Cenozoic igneous rocks from the South Shetland Arc, Antarctica. Lithos, 82(3–4): 435–453 https://doi.org/10.1016/j.lithos.2004.09.026

Martin, H., 1993. The mechanisms of petrogenesis of the Archaean continental crust, comparison with modern processes. Lithos, 30(3–4): 373–388. https://doi.org/10.1016/0024-4937(93)90046-F

Martin, H., Smithies, R.H., Rapp, R., Moyen, J.F. and Champion, D., 2005. An overview of adakite, tonalite–trondhjemite–granodiorite (TTG) and sanukitoid: relationships and some implications for crustal evolution. Lithos, 79(1–2): 1–24. https://doi.org/10.1016/j.lithos.2004.04.048

McDonough, W.F. and Sun, S.S., 1995. Composition of the Earth. Chemical Geology, 120(3–4): 223–253. https://doi.org/10.1016/0009-2541(94)00140-4

Middlemost, E.A. K., 1994. Naming materials in the magma and igneous rock system. Science Reviews, 37(3-4): 215–224. https://doi.org/10.1016/0012-8252(94)90029-9

Mokhtari, M.A.A., Kouhestani, H. and Bavi, M.H., 2023. Moghanlou Sb deposit (west of Zanjan): Evidence of geology, mineralization, and fluid inclusions. 25^th Conference of the geological society of Iran, Shahroud University of Technology, Shahroud, Iran. (in Persian with extended English abstract) Retrieved January 15, 2024 from https://gsi25.shahroodut.ac.ir/fa/files.php

Muller, D. and Groves, D.I., 1997. Potassic igneous rocks and associated gold copper mineralization. 2^nd edition, Springer, Verlag, Berlin, 311 pp. https://doi.org/10.1007/978-3-319-23051-1

Najafzadeh, M., Ebrahimi, M., Mokhtari, M.A.A. and Kouhestani, H., 2017. The Arabshah occurrence: an epithermal Au-As-Sb Carlin-type mineralization in the Takab-Angouran-Takht-e-Soleyman metallogenic zone, western Azerbaijan. Advance applied Geology, 6(4): 62–77. (in Persian with extended English abstract) https://doi.org/10.22055/aag.2016.12709

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(11): 234–251. https://doi.org/10.1016/j.lithos.2013.05.009

Pearce, J.A., 1983. Role of the sub-continental lithosphere in magma genesis at active continental margins. C.J. Hawkesworth and M.J.  Norry (Editors), Continental basalts and mantle xenoliths, Nantwich, Cheshire: Shiva Publications, pp. 230–249. https://orca.cardiff.ac.uk/id/eprint/8626

Peccerillo, A. and Taylor, S.R., 1976. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Contributions to Mineralogy and Petrology, 58(1): 63–81. https://doi.org/10.1007/BF00384745

Plank, T., 2005. Constraints from Thorium/Lanthanum on sediment recycling at subduction zones and the Evolution of the Continents. Journal of Petrology, 46(5): 921–944. https://doi.org/10.1093/petrology/egi005

Rezaei Kahkhaei, M., Corfu, F., Galindo, C., Rahbar, R. and Ghasemi, H., 2022. Adakite genesis and plate convergent process: Constraints from whole rock and mineral chemistry, Sr, Nd, Pb isotopic compositions and U-Pb ages of the Lakhshak magmatic suite, East Iran. Lithos, 426–427. https://doi.org/10.1016/j.lithos.2022.106806

Rezaei Kahkhaei, M., Taheri, S.A., Ghasemi, H. and Gardideh, S., 2018. Geochemistry and isotope geology of adakitic domes from Chakane area in south of Quchan (northeast of Iran). Petrological Journal, 9(4): 25–48. (in Persian with extended English abstract) https://doi.org/10.22108/ijp.2018.104209.1031

Rollinson, H.R., 1993. Using Geochemical Data: Evolution, Presentation, Interpretation. Longman Scientific and Technical. England, 384 pp. https://doi.org/10.4324/9781315845548

Rudnick, R.L. and Gao, S., 2003. Composition of the continental Crust. Treatise on Geochemistry, 3(1): 1–64. https://doi.org/10.1016/B0-08-043751-6/03016-4

Saadat, S., 2023. Adakitic magmatism, a window to evolution on tectonic and mineralization in eastern Iran. Journal of Economic Geology, 15(1): 87–113. (in Persian with English abstract) https://doi.org/10.22067/econg.2023.80308.1062

Sabzi, Z., Mokhtari, M.A.A. and Ebrahimi, M., 2018. Petrology and geochemistry of Ayoub Ansar volcanic dome, southeast Takab. Researches in Earth Sciences, 9(1): 103–117. https://doi.org/10.29252/esrj.9.1.103

Saccani, E., 2015. A new method of discriminating different types of post-Archean ophiolitic basalts and their tectonic significance using Th-Nb and Ce-Dy-Yb systematics. Geoscience Frontiers, 6(4): 481–501. https://doi.org/10.1016/j.gsf.2014.03.006

Sun, S.S. and McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: A.D. Saunders and M.J. Norry (Editors), Magmatism in the Ocean Basins. Geological Society, London, Special Publication, 42: pp. 313–345. https://doi.org/10.1144/GSL.SP.1989.042.01.19

Turner, S., Arnaud, N., Liu, J., Rogers, N., Hawkesworth, C., Harris, N., Kelley, S., Van Calsteren, P. and Deng, W., 1996. Post-collision, shoshonitic volcanism on the Tibetan, Plateau: implications for convective thinning of the lithosphere and source of ocean island basalts. Journal of Petrology, 37(1): 45–71. https://doi.org/10.1093/petrology/37.1.45

Varekamp, J.C., Hesse, A. and Mandeville, C.W., 2010. Back-arc basalts from the Loncopue graben (province of Neuquen, Argentina). Journal of Volcanology and Geothermal Research, 197(1): 313–328. https://doi.org/10.1016/j.jvolgeores.2010.04.003

Vetrin, V.R. and Rodionov, N.V., 2008. Sm-Nd Systematics and petrology of post-orogenic Granitoids in the Northern Baltic Shield. Geochemistry International, 46(11): 1090–1106. https://doi.org/10.1134/S0016702908110037

Wallin, E.T. and Metcalf, R.V., 1998. Supra-subduction zone ophiolite formed in an extensional forearc: Trinity Terrane, Klamath Mountains, California. The Journal of Geology, 106(5): 591–608. https://doi.org/10.1086/516044

Wang, K.L. and Chung, S.L., 2004. Geochemical constraints for the genesis of post-collisional magmatism and the geodynamic evolution of the northern Taiwan region. Journal of Petrology, 45(5): 975–1011. https://doi.org/10.1093/petrology/egh001

Wang, Q., McDermott, F., Xu, J.F., Bellon, H. and Zhu, Y.T., 2005. Cenozoic K-rich adakitic volcanic rocks in the Hohxil area, northern Tibet: lower-crustal melting in an intracontinental setting. Geology, 33(6): 465–468. https://doi.org/10.1130/G21522.1

Wang, Q., Wyman, D.A., Xu, J.F., Wan, Y.S., Li, C.F., Zi, F., Jiang, Z.Q., Qiu, H.N., Chu, Z.Y. Zhao, Z.H. and Dong, Y.H., 2007. Triassic Nb-enriched basalts, magnesian andesites, and adakites of the Qiangtang terrane (Central Tibet): evidence for metasomatism by slab derived melts in the mantle wedge. Contribution to Mineralogy and Petrology, 155(4): 473–490. https://doi.org/10.1007/s00410-007-0253-1

Wayer, S., Munker, C. and Mezgar, K., 2003. Nb/Ta, Zr/Hf and REE in the depleted mantle: implications for the differentiation history of the crust-mantle system. Earth and Planetary Scince Letters, 205(3–4): 306–324. https://doi.org/10.1016/S0012-821X(02)01059-2

Wilson, M., 1989. Igneous Petrogenesis. Chapman and Hall, London, 466 pp. https://doi.org/10.1007/978-94-010-9388-0

Winchester, J.A. and Floyd, P.A., 1977. Geochemical classification of different magma series and their differentiation products using immobile elements. Chemical Geology, 20(5): 325–343. https://doi.org/10.1016/0009-2541(77)90057-2

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

Yousefi, F., Sadeghian, M., Wanhainen, C., Ghasemi, H., Lambrini, P., Bark, G., Rezaei Kahkhaei, M. and Koroneos, A., 2017. Mineral Chemistry and P-T Conditions of the adakitic rocks from Torud-Ahmad Abad Magmatic Belt, S-SE Shahrood, Iran. Journal of Geochemical Exploration, 182(10): 110–120. https://doi.org/10.1016/j.gexplo.2017.09.006