Petrogenetic Processes in Andesite Generation: Insights from Walash Volcanic Arc

Volume 27 , Issue 2 , December 2025 , Pages 98-114

Authors

Jabbar M. A. Qaradaghi 1

1 Department of Earth Sciences and Petroleum, College of Science, University of Sulaimani, Sulaimani city, Kurdistan region, Iraq

DOI logo 10.17656/sujpas.1118

Keywords

Abstract

Andesites are characteristic rocks of subduction zone magmatism. Andesitic rocks investigated from Walash Volcanics (WV) throughout field, petrological, mineralogical, and geochemical aspects, classifying into two types pyroxene-rich (px-andesite) and hornblende-rich (hbl-andesite). This study is the first to report well-formed magmatic hornblende crystals in andesitic rocks from the Mawat area in Iraqi Kurdistan. Andesites, in WV, are comprised of plagioclase, pyroxene, and hornblende phenocrysts along with a groundmass of plagioclase, hematite, and sanidine. XRD examination indicates that the plagioclase grains are predominantly composed of albite. Andesitic rock samples (px-andesite and hbl-andesite) show typical porphyritic and magmatic flow textures. The primary alteration product includes sericite after plagioclase. ICP-MS analysis shows that andesitic rock samples tend to be high-Mg andesites, and their magma formed out of the field of mantle-derived melts. Furthermore, hbl-andesite rock samples represent normal calc-alkaline andesites, while the px-andesites represent the andesites from more mature arcs. Geochemical discriminations based on diagnostic trace elemental ratios indicate that the pyroxene and hornblende andesites both formed within a volcanic arc tectonic setting. The px-andesite exhibit compositions proximal to the average continental crust and align with magmas from a normal island arc with fractionation trends dominated by plagioclase. In contrast, the hbl-andesite reveals a distinct adakitic signature, characterized by elevated Sr/Y and La/Yb ratios, and their compositional trends are consistent with a fractionation process controlled by hornblende and pyroxene. This geochemical contradiction suggests two different petrogenetic pathways: firstly, the px-andesites likely originated from typical mantle wedge melting, secondly the adakitic nature of the hbl-andesites may be derived from partial melting of a subducted slab or assimilation of lower crustal material.

References

  1. Al-Kadhimi, J., Sissakian, V., Fattah, A., & Deikran, D. (1996). Tectonic Map of Iraq, 2nd edit., scale 1:1000 000. GEOSURV, Baghdad, Iraq.
  2. Al-Qayim, B., Omer, A., & Koyi, H. (2012). Tectonostratigraphic overview of the Zagros suture zone, Kurdistan region, Northeast Iraq. [Research Article]. GeoArabia, 17(4), 109-156.
  3. Ali, S. A., Buckman, S., Aswad, K. J., Jones, B. G., Ismail, S. A., & Nutman, A. P. (2013). The tectonic evolution of a Neo‐Tethyan (Eocene–Oligocene) island‐arc (Walash and Naopurdan groups) in the Kurdistan region of the Northeast Iraqi Zagros Suture Zone. Island Arc, 22(1), 104-125.
  4. Aswad, K. J. A., Al-Samman, A. H. M., Aziz, N. R. H., & Koyi, A. M. A. (2013). The geochronology and petrogenesis of Walash volcanic rocks, Mawat nappes: constraints on the evolution of the northwestern Zagros suture zone, Kurdistan Region, Iraq. Arabian Journal of Geosciences, 7(4), 1403-1432. https://doi.org/10.1007/s12517-013-0873-x
  5. Aziz, N. R. (1986). Petrochemistry, petrogenesis and tectonic setting of spilitic rocks of Walash volcanosedimentary group in Qala-Diza area, NE Iraq. Unpub [MSc Thesis, Mosul].
  6. Bolton, C. (1958). The geology of the Ranya area. Manuscript report No. 271. GEOSURV, Baghdad.
  7. Buday, T., & Jassim, S. (1987). The regional geology of Iraq, vol. 2: tectonism, magmatism and metamorphism. GEOSURV, Baghdad, 352pp.
  8. Cassidy, M., Edmonds, M., Watt, S. F., Palmer, M. R., & Gernon, T. M. (2015). Origin of basalts by hybridization in andesite-dominated arcs. Journal of Petrology, 56(2), 325-346.
  9. Castillo, P. R. (2012). Adakite petrogenesis. Lithos, 134, 304-316.
  10. Chen, L., Zheng, Y.-F., Xu, Z., & Zhao, Z.-F. (2021). Generation of andesite through partial melting of basaltic metasomatites in the mantle wedge: Insight from quantitative study of Andean andesites. Geoscience Frontiers, 12(3), 101124.
  11. Chiaradia, M. (2009). Adakite-like magmas from fractional crystallization and meltingassimilation of mafic lower crust (Eocene Macuchi arc, Western Cordillera, Ecuador). Chemical geology, 265(3-4), 468-487.
  12. Chung, S.-L., Liu, D., Ji, J., Chu, M.-F., Lee, H.-Y., Wen, D.-J., Lo, C.-H., Lee, T.-Y., Qian, Q., & Zhang, Q. (2003). Adakites from continental collision zones: melting of thickened lower crust beneath southern Tibet. Geology, 31(11), 1021-1024.
  13. Collins, W. J., Murphy, J. B., Johnson, T. E., & Huang, H.-Q. (2020). Critical role of water in the formation of continental crust. Nature Geoscience, 13(5), 331-338.
  14. Condie, K. C. (2005). TTGs and adakites: are they both slab melts? Lithos, 80(1-4), 33-44.
  15. Danyushevsky, L. V., McNeill, A. W., & Sobolev, A. V. (2002). Experimental and petrological studies of melt inclusions in phenocrysts from mantle-derived magmas: an overview of techniques, advantages and complications. Chemical geology, 183(1-4), 5-24.
  16. Davidson, J., Turner, S., Handley, H., Macpherson, C., & Dosseto, A. (2007). Amphibole “sponge” in arc crust? Geology, 35(9), 787-790.
  17. Defant, M. J., & Drummond, M. S. (1990). Derivation of some modern arc magmas by melting of young subducted lithosphere. nature, 347(6294), 662-665.
  18. Defant, M. J., & Kepezhinskas, P. (2001). Evidence suggests slab melting in arc magmas. Eos, Transactions American Geophysical Union, 82(6), 65-69.
  19. Erdmann, S., Chen, L. H., Liu, J. Q., Xue, X. Q., & Wang, X. J. (2019). Hot, volatile‐poor, and oxidized magmatism above the stagnant Pacific plate in Eastern China in the Cenozoic. Geochemistry, Geophysics, Geosystems, 20(11), 4849-4868.
  20. Fan, W.-M., Guo, F., Wang, Y.-J., & Zhang, M. (2004). Late Mesozoic volcanism in the northern Huaiyang tectono-magmatic belt, central China: partial melts from a lithospheric mantle with subducted continental crust relicts beneath the Dabie orogen? Chemical geology, 209(1-2), 27-48.
  21. Gao, M.-H., Liu, P.-P., Chung, S.-L., Li, Q.-L., Wang, B., Tian, W., Li, X.-H., & Lee, H.-Y. (2022). Himalayan zircons resurface in Sumatran arc volcanoes through sediment recycling. Communications Earth & Environment, 3(1), 283.
  22. Gill, J. B. (2012). Orogenic andesites and plate tectonics (Vol. 16). Springer Science & Business Media.
  23. Gill, R., & Fitton, G. (2022). Igneous rocks and processes: a practical guide. John Wiley & Sons.
  24. Hernández-Uribe, D., Hernández-Montenegro, J. D., Cone, K. A., & Palin, R. M. (2020). Oceanic slab-top melting during subduction: Implications for trace-element recycling and adakite petrogenesis. Geology, 48(3), 216-220.
  25. Hofmann, A. W. (1988). Chemical differentiation of the Earth: the relationship between mantle, continental crust, and oceanic crust. Earth and planetary science letters, 90(3), 297-314.
  26. Huang, F., & He, Y. (2010). Partial melting of the dry mafic continental crust: implications for petrogenesis of C-type adakites. Chinese Science Bulletin, 55, 2428-2439.
  27. Jahn, B.-m., Wu, F., Lo, C.-H., & Tsai, C.-H. (1999). Crust–mantle interaction induced by deep subduction of the continental crust: geochemical and Sr–Nd isotopic evidence from post-collisional mafic–ultramafic intrusions of the northern Dabie complex, central China. Chemical geology, 157(1-2), 119-146.
  28. Jassim, S. Z., & Goff, J. C. (2006). Geology of Iraq. DOLIN, sro, distributed by Geological Society of London.
  29. Kawaraṅ, H., Matsumoto, M., & Kuritani, T. (2025). Generation of andesitic–dacitic magmas by open-system progressive melting of the middle crust in Rishiri Volcano, northern Japan. Lithos, 108221.
  30. Kelemen, P., Hanghøj, K., & Greene, A. (2003). One view of the geochemistry of subduction-related magmatic arcs, with an emphasis on primitive andesite and lower crust. Treatise on geochemistry, 3, 659.
  31. Kelemen, P. B. (1995). Genesis of high Mg# andesites and the continental crust. Contributions to Mineralogy and Petrology, 120(1), 1-19.
  32. Koyi, A. (2009). Sr-Nd isotopical significance of Walash volcanic rocks, Mawat area, NE Iraq. Zanco J Pure Sci Salahaddin University, Hawler, 21, 39-45.
  33. LeBas, M., Maitre, R. L., Streckeisen, A., Zanettin, B., & Rocks, I. S. o. t. S. o. I. (1986). A chemical classification of volcanic rocks based on the total alkali-silica diagram. Journal of Petrology, 27(3), 745-750.
  34. Li, C., Niu, M., Yuan, X., Yan, Z., Wu, Q., Li, X., & Sun, Y. (2022). Geochemical signals of coexisting magma mixing and fractional crystallization processes in the arc setting: Case study of Wulan intrusive suite in the NE Tibet Plateau. Lithos, 432, 106914.
  35. Luchitskaya, M. (2022). The composition, petrogenesis, and geodynamic setting of adakite magmatism: An overview. Geotectonics, 56(4), 486-519.
  36. Ma, Q., Zheng, J.-P., Xu, Y.-G., Griffin, W. L., & Zhang, R.-S. (2015). Are continental “adakites” derived from thickened or foundered lower crust? Earth and planetary science letters, 419, 125-133.
  37. Mibe, K., Kawamoto, T., Matsukage, K. N., Fei, Y., & Ono, S. (2011). Slab melting versus slab dehydration in subduction-zone magmatism. Proceedings of the National Academy of Sciences, 108(20), 8177-8182.
  38. Mohammad, Y. O., Cornell, D. H., Qaradaghi, J. H., & Mohammad, F. O. (2014). Geochemistry and Ar–Ar muscovite ages of the Daraban Leucogranite, Mawat Ophiolite, northeastern Iraq: implications for Arabia–Eurasia continental collision. Journal of Asian Earth Sciences, 86, 151-165.
  39. Mohammad, Y. O., and Qaradaghi, J. H. (2016). Geochronological and mineral chemical constraints on the age and formation conditions of the leucogranite in the Mawat ophiolite, Northeastern of Iraq: insight to sync-subduction zone granite. Arab J Geosci 9, 608. https://doi.org/10.1007/s12517-016-2630-4
  40. Polat, A., & Hofmann, A. (2003). Alteration and geochemical patterns in the 3.7–3.8 Ga Isua greenstone belt, West Greenland. Precambrian Research, 126(3-4), 197-218.
  41. Qaradaghi, J. M. A. (2024). Genesis and Tectonics of Basaltic Pillow lava and Peperites within Walash Volcano-sedimentary group, Mawat area, Iraqi Kurdistan Region [Ph.D Thesis, University of Sulaimani]. University of Sulaimani.
  42. Qaradaghi, J. M. A., & Mirza, T. A. (2023). Peperites: Insight into the Submarine Eruptions within Walash Volcanosedimentary Group, Mawat Area, Iraqi Kurdistan Region. ARO: The Scientific Journal of Koya University, 11(2).
  43. Qaradaghi, J. M., Mohammed, Y. O., and Aziz, S. A., (2019). Petrology and Geochemistry of Gole Pillow Basalt in Penjween area Kurdistan Region-NE Iraq. Tikrit Journal of Pure Science, 24(7), 66-81. https://doi.org/10.25130/tjps.v24i7.460
  44. Qaradaghi, J. M. A., (2012). Petrogenesis and Geochronology of Granitoid Rocks in Mawat Ophiolite from Kurdistan Region, Northeastern Iraq [MSc thesis, University of Sulaimani]. University of Sulaimani.
  45. Qian, Q., & Hermann, J. (2013). Partial melting of lower crust at 10–15 kbar: constraints on adakite and TTG formation. Contributions to Mineralogy and Petrology, 165(6), 1195-1224.
  46. Rapp, R., Norman, M., Laporte, D., Yaxley, G., Martin, H., & Foley, S. (2010). Continent formation in the Archean and chemical evolution of the cratonic lithosphere: melt–rock reaction experiments at 3–4 GPa and petrogenesis of Archean Mg-diorites (sanukitoids). Journal of Petrology, 51(6), 1237-1266.
  47. Rapp, R. P., & Watson, E. B. (1995). Dehydration melting of metabasalt at 8–32 kbar: implications for continental growth and crust-mantle recycling. Journal of Petrology, 36(4), 891-931.
  48. Reubi, O., & Müntener, O. (2022). Making Andesites and the Continental Crust: Mind the Step When Wet. Journal of Petrology, 63(6). https://doi.org/10.1093/petrology/egac044.
  49. Ruiz‐Mendoza, V., Verma, S. K., Torres‐Sánchez, D., Barry, T. L., Moreno, J. A., & Torres‐Hernández, J. R. (2021). Geochemistry and geochronology of intermediate volcanic rocks from the Compostela area, Nayarit, Mexico: Implications for petrogenesis and tectonic setting. Geological Journal, 56(8), 4401-4428.
  50. Saikia, A., Akhtar, S., & Negi, P. (2022). Role of fractional crystallization and partial melting in the generation of intermediate and acidic magmas of the Andaman Island Ophiolite suite of India. Geological Journal, 57(2), 906-924.
  51. Straub, S. M., Gómez-Tuena, A., & Vannucchi, P. (2020). Subduction erosion and arc volcanism. Nature Reviews Earth & Environment, 1(11), 574-589.
  52. Sun, S.-S., & McDonough, W. F. (1989). Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geological Society, London, Special Publications, 42(1), 313-345.
  53. Sun, W.-D., Ling, M.-X., Chung, S.-L., Ding, X., Yang, X.-Y., Liang, H.-Y., Fan, W.-M., Goldfarb, R., & Yin, Q.-Z. (2012). Geochemical constraints on adakites of different origins and copper mineralization. The Journal of Geology, 120(1), 105-120.
  54. Szilas, K., Tusch, J., Hoffmann, J. E., Garde, A. A., & Münker, C. (2017). Hafnium isotope constraints on the origin of Mesoarchaean andesites in southern West Greenland, North Atlantic Craton.
  55. Tatsumi, Y., & Eggins, S. (1995). Subduction zone magmatism (Vol. 1). Wiley.
  56. Taylor, S. R., & McLennan, S. M. (1995). The geochemical evolution of the continental crust. Reviews of geophysics, 33(2), 241-265.
  57. Wang, X., Sun, M., Cai, K., Zhao, G., Xiao, W., Xia, X., & Li, P. (2024). Crustal recycling and growth via mélange diapir in subduction zones: Insights from two episodes of magmatism in the Northern Yili Block, NW China. Bulletin, 136(1-2), 774-792.
  58. Xu, J., Xia, X.-P., Wang, Q., Spencer, C. J., Lai, C.-K., & Zhang, L. (2022). Two magma fractionation paths for continental crust growth: Insights from the adakite-like and normal-arc granites in the Ailaoshan fold belt (SW Yunnan, China). Bulletin, 134(11-12), 2986-3002.
  59. Yan, H., Long, X., Li, J., Wang, Q., Zhao, B., Shu, C., Gou, L., & Zuo, R. (2019). Arc andesitic rocks derived from partial melts of mélange diapir in subduction zones: Evidence from whole‐rock geochemistry and Sr‐Nd‐Mo isotopes of the Paleogene Linzizong volcanic succession in southern Tibet. Journal of Geophysical Research: Solid Earth, 124(1), 456-475.
  60. Ye, X.-T., Zhang, C.-L., Wang, A.-G., Wu, B., & Wang, G.-D. (2018). Early Paleozoic slab rollback in the North Altun, Northwest China: New evidence from mafic intrusions and high-Mg andesites. Lithosphere, 10(6), 687-707.
  61. Zhang, G., Zhang, J., Dalton, H., & Phillips, D. (2022). Geochemical and chronological constraints on the origin and mantle source of Early Cretaceous arc volcanism on the Gagua Ridge in western Pacific. Geochemistry, Geophysics, Geosystems, 23(9), e2022GC010424.
  62. Zhong, Y., Chen, L.-H., Wang, X.-J., Zhang, G.-L., Xie, L.-W., & Zeng, G. (2017). Magnesium isotopic variation of oceanic island basalts generated by partial melting and crustal recycling. Earth and planetary science letters, 463, 127-135.
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