Skip to main content

Petrogenesis of plagiogranites in the Muslim Bagh Ophiolite, Pakistan: implications for the generation of Archaean continental crust

  • DANIEL COX (a1) (a2), ANDREW C. KERR (a2), ALAN R. HASTIE (a1) and M. ISHAQ KAKAR (a3)

High-SiO2 rocks referred to as oceanic plagiogranites are common within the crustal sequences of ophiolites; however, their mode of petrogenesis is controversial with both late-stage fractional crystallization and partial melting models being proposed. Here, we present new whole-rock data from plagiogranitic dyke-like bodies and lenses from the lower and middle sections of the sheeted dyke complex of the Cretaceous Muslim Bagh Ophiolite, northwestern Pakistan. The plagiogranites have similar geochemical signatures that are inconsistent with them being the fractionation products of the mafic units of the Muslim Bagh Ophiolite. However, the plagiogranites all display very low TiO2 contents (<0.4 wt%), implying that they formed by partial melting of mafic rocks. Melt modelling of a crustal gabbro from the Muslim Bagh Ophiolite shows that the trace-element signature of the plagiogranites can be replicated by 5–10% melting of a crustal hornblende gabbro with amphibole as a residual phase, resulting in a concave-up middle rare Earth element pattern. Compositional similarities between the Muslim Bagh Ophiolite plagiogranites and Archaean TTG (trondhjemite–tonalite–granodiorite) has implications for the generation of juvenile Archaean continental crust. As the Muslim Bagh Ophiolite was derived in a supra-subduction zone, it is suggested that some Archaean TTG may have been derived from melting of mafic upper crust in early subduction-like settings. However, due to the small volume of Muslim Bagh Ophiolite plagiogranites, it is inferred that they can be instructive on the petrogenesis of some, but not all, Archaean TTG.

Corresponding author
Author for correspondence:
Hide All
Ahmad, Z. & Abbas, S. G. 1979. The Muslim Bagh Ophiolites. In Geodynamics of Pakistan (eds Farah, A. & DeJong, A.), pp. 243–51. Pakistan: Geological Survey of Pakistan.
Amri, I., Benoit, M. & Ceuleneer, G. 1996. Tectonic setting for the genesis of oceanic plagiogranites: evidence from a paleo-spreading structure in the Oman Ophiolite. Earth and Planetary Science Letters 139, 177–94.
Aranovich, L. Y., Bortnikov, N. S., Serebryakov, N. S. & Sharkov, E. V. 2010. Conditions of the formation of plagiogranite from the Markov Trough, Mid-Atlantic Ridge, 5°52′-6°02′N. Doklady Earth Sciences 434, 1257–62.
Asrarullah, Ahmad Z. & Abbas, S. G. 1979. Ophiolites in Pakistan: an introduction. In Geodynamics of Pakistan (eds Farah, A. & DeJong, A.), pp. 181–92. Pakistan: Geological Survey of Pakistan.
Barker, F. 1979. Trondhjemite: definition, environment and hypothesis of origin. In Trondhjemites, Dacites, and Related Rocks (ed. Barker, F.), pp. 112. Amsterdam: Elsevier.
Beard, J. S. & Lofgren, G. E. 1991. Dehydration melting and water-saturated melting of basaltic and andesitic greenstones and amphibolites at 1, 3 and 6.9 kb. Journal of Petrology 32, 365401.
Bedard, J. H. 2006. A catalytic delamination-driven model for coupled genesis of Archean crust and sub-continental lithospheric mantle. Geochimica et Cosmochimica Acta 70, 1188–214.
Coleman, R. G. & Donato, M. M. 1979. Oceanic plagiogranite revisited. In Trondhjemites, Dacites, and Related Rocks (ed. Barker, F.), pp. 149–68. Amsterdam: Elsevier.
Coleman, R. G. & Peterman, Z. E. 1975. Oceanic plagiogranite. Journal of Geophysical Research 80, 1099–108.
Condie, K. C. 2005. TTGs and adakites: are they both slab melts? Lithos 80, 3344.
Davidson, J., Turner, S. & Plank, T. 2012. Dy/Dy*: Variations arising from mantle sources and petrogenetic processes. Journal of Petrology 54, 525–37.
Dick, H. J. B., Natland, J. H., Alt, J. C., Bach, W., Bideau, D., Gee, J. S., Haggas, S., Hertogen, J. G. H., Hirth, G., Holm, P. M., Ildefonse, B., Iturrino, G. J., John, B. E., Kelley, D. S., Kikawa, E., Kingdon, A., LeRoux, P. J., Maeda, J., Meyer, P. S., Miller, J., Naslund, H. R., Niu, Y. -L., Robinson, P. T., Snow, J., Stephen, R. A., Trimby, P. W., Worm, H. -U. & Yoshinobu, A. 2000. A long in situ section of the lower crust: results of ODP Leg 176 drilling at the Southwest Indian Ridge. Earth and Planetary Science Letters 179, 3151.
Dixon, S. & Rutherford, M. J. 1979. Plagiogranites as late-stage immiscible liquids in ophiolite and mid-ocean ridge suites an experimental study. Earth and Planetary Science Letters 45, 4560.
Drummond, M. S., Defant, M. J. & Kepezhinskas, P. K. 1996. Petrogenesis of slab-derived trondhjemite-tonalite-dacite/adakite magmas. Transactions of the Royal Society of Edinburgh 87, 205–15.
Erdmann, M., Fischer, L. A., France, L., Zhang, C., Godard, M. & Koepke, J. 2015. Anatexis at the roof of an oceanic magma chamber at IODP Site 1256 (equatorial Pacific): an experimental study. Contributions to Mineralogy and Petrology 169, 128.
Flagler, P. A. & Spray, J. G. 1991. Generation of plagiogranite by amphibolite anatexis in oceanic shear zones. Geology 19, 70–3.
Floyd, P. A. & Winchester, J. A. 1975. Magma type and tectonic setting discrimination using immobile elements. Earth and Planetary Science Letters 27, 211–8.
Foley, S. F., Tiepolo, M. & Vannucci, R. 2002. Growth of early continental crust controlled by melting of amphibolite in subduction zones. Nature 417, 837–40.
France, L., Ildefonse, B. & Koepke, J. 2009. Interactions between magma and hydrothermal system in Oman Ophiolite and in IODP Hole 1256D: fossilization of a dynamic melt lens at fast spreading ridges. Geochemistry, Geophysics, Geosystems 10, 130.
France, L., Koepke, J., Ildefonse, B., Cichy, S. B. & Deschamps, F. 2010. Hydrous partial melting in the sheeted dike complex at fast spreading ridges: experimental and natural observations. Contributions to Mineralogy and Petrology 160, 683704.
Freund, S., Haase, K. M., Keith, M., Beier, C. & Garbe-Schonberg, D. 2014. Constraints on the formation of geochemically variable plagiogranite intrusions in the Troodos Ophiolite, Cyprus. Contributions to Mineralogy and Petrology 167, 122.
Gerlach, D. C., Leeman, W. P. & Ave Lallemant, H. G. 1981. Petrology and geochemistry of plagiogranite in the Canyon Mountain Ophiolite, Oregon. Contributions to Mineralogy and Petrology 77, 8292.
Gillis, K. M. & Coogan, L. A. 2002. Anatectic migmatites from the roof of an ocean ridge magma chamber. Journal of Petrology 43, 2075–95.
Gnos, E., Immenhauser, A. & Peters, T. 1997. Late Cretaceous/early Tertiary convergence between the Indian and Arabian plates recorded in ophiolites and related sediments. Tectonophysics 271, 119.
Grimes, C. B., Ushikubo, T., John, B. E. & Valley, J. W. 2011. Uniformly mantle-like Delta18O in zircons from oceanic plagiogranites and gabbros. Contributions to Mineralogy and Petrology 161, 1333.
Hamilton, W. B. 1998. Archean magmatism and deformation were not products of plate tectonics. Precambrian Research 91, 143–79.
Hastie, A. R., Fitton, J. G., Bromiley, G. D., Butler, I. B. & Odling, N. W. A. 2016. The origin of Earth's first continents and the onset of plate tectonics. Geology 44, 855–8.
Hastie, A. R., Fitton, J. G., Mitchell, S. F., Neill, I. M., Nowell, G. & Millar, I. L. 2015. Can fractional crystallization, mixing and assimilation processes be responsible for Jamaican-type adakites? Implications for generating EoArchean continental crust. Journal of Petrology 56, 1251–84.
Hastie, A. R., Kerr, A. C., Mitchell, S. F. & Millar, I. L. 2009. Geochemistry and tectonomagmatic significance of lower Cretaceous island arc lavas from the Devils Racecourse Formation, eastern Jamaica. In The Origin and Evolution of the Caribbean Plate (eds James, K. H., Lorente, M. A. & Pindell, J. L.), pp. 339–60. Geological Society of London, Special Publication no. 328.
Hastie, A. R., Kerr, A. C., Pearce, J. A. & 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, 2341–57.
Hawkesworth, C. J., Cawood, P. A. & Dhuime, B. 2016. Tectonics and crustal evolution. GSA Today 26, 411.
Jafri, S. H., Charan, S. N. & Govil, P. K. 1995. Plagiogranite from the Andaman Ophiolite Belt, Bay of Bengal, India. Journal of the Geological Society, London 152, 681–7.
Kakar, M. I., Collins, A. S., Mahmood, K., Foden, J. D. & Khan, M. 2012. U-Pb zircon crystallization age of the Muslim Bagh Ophiolite: Enigmatic remains of an extensive pre-Himalayan arc. Geology 40, 1099–102.
Kakar, M. I., Kerr, A. C., Mahmood, K., Collins, A. S., Khan, M. & McDonald, I. 2014. Supra-subduction zone tectonic setting of the Muslim Bagh Ophiolite, northwestern Pakistan: Insights from geochemistry and petrology. Lithos 202–203, 190206.
Kasi, A. K., Kassi, A. M., Umar, M., Manan, R. A. & Kakar, M. I. 2012. Revised lithostratigraphy of the Pishin Belt, northwestern Pakistan. Journal of Himalayan Earth Sciences 45, 5365.
Kaur, G. & Mehta, P. K. 2005. The Gothara plagiogranite: evidence for oceanic magmatism in a non-ophiolitic association, North Khetri Copper Belt, Rajasthan, India? Journal of Asian Earth Sciences 25, 805–19.
Kerrich, R. & Polat, A. 2006. Archean greenstone-tonalite duality: Thermochemical mantle convection models or plate tectonics in the early Earth global dynamics? Tectonophysics 415, 141–65.
Khan, M., Kerr, A. C. & Mahmood, K. 2007. Formation and tectonic evolution of the Cretaceous-Jurassic Muslim Bagh ophiolitic complex, Pakistan: implications for the composite tectonic setting of ophiolites. Journal of Asian Earth Sciences 31, 112–27.
Khan, S. D., Mahmood, K. & Casey, J. F. 2007. Mapping of Muslim Bagh ophiolite complex (Pakistan) using new remote sensing, and field data. Journal of Asian Earth Sciences 30, 333–43.
Khan, S. D., Walker, D. J., Hall, S. A., Burke, K. C., Shah, M. T. & Stockli, L. 2009. Did the Kohistan-Ladakh island arc collide first with India? Bulletin of the Geological Society of America 121, 366–84.
Koepke, J., Berndt, J., Feig, S. T. & Holtz, F. 2007. The formation of SiO2-rich melts within the deep oceanic crust by hydrous partial melting of gabbros. Contributions to Mineralogy and Petrology 153, 6784.
Koepke, J., Feig, S. T., Snow, J. & Freise, M. 2004. Petrogenesis of oceanic plagiogranites by partial melting of gabbros: an experimental study. Contributions to Mineralogy and Petrology 146, 414–32.
Kusky, T. M., Windley, B. F., Safonova, I., Wakita, K., Wakabayashi, J., Polat, A. & Santosh, M. 2013. Recognition of ocean plate stratigraphy in accretionary orogens through Earth history: a record of 3.8 billion years of sea floor spreading, subduction, and accretion. Gondwana Research 24, 501–47.
Laurent, O., Doucelance, R., Martin, H. & Moyen, J. F. 2013. Differentiation of the late-Archean sanukitoid series and some implications for crustal growth: Insights from geochemical modelling on the Bulai pluton, Central Limpopo Belt, South Africa. Precambrian Research 227, 186203.
Laurie, A. & Stevens, G. 2012. Water-present eclogite melting to produce Earth's early felsic crust. Chemical Geology 314–317, 8395.
Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B. & Bateman, P. (eds) 2002. Igneous Rocks: A Classification and Glossary of Terms. Cambridge: Cambridge University Press.
Mahmood, K., Boudier, F., Gnos, E., Monie, P. & Nicolas, A. 1995. 40Ar/39Ar dating of the emplacement of the Muslim Bagh Ophiolite, Pakistan. Tectonophysics 250, 169–81.
Martin, H., Smithies, R. H., Rapp, R., Moyen, J. F. & Champion, D. 2005. An overview of adakite, tonalite-trondhjemite-granodiorite (TTG), and sanukitoid: Relationships and some implications for crustal evolution. Lithos 79, 124.
McDonald, I. & Viljoen, K. S. 2006. Platinum-group element geochemistry of mantle eclogites: a reconnaissance study of xenoliths from the Orapa kimberlite, Botswana. Applied Earth Science 115, 8193.
Mengal, J. M., Kimura, K., Siddiqui, R. H., Kojima, S., Naka, T., Bakht, M. S. & Kamada, K. 1994. The lithology and structure of a Mesozoic sedimentary-igneous assemblage beneath the Muslim Bagh Ophiolite, northern Balochistan, Pakistan. Bulletin of the Geological Survey of Japan 2, 5161.
Milovanovic, D., Sreckovic-Batocanin, D., Savic, M. & Popovic, D. 2012. Petrology of plagiogranite from Sjenica, Dinaridic Ophiolite Belt (southwestern Serbia). Geologica Carpathica 63, 97106.
Moyen, J. F. & Martin, H. 2012. Forty years of TTG research. Lithos 148, 312–36.
Moyen, J. F. & Stevens, G. 2006. Experimental constraints on TTG petrogenesis: implications for Archean geodynamics. In Archean Geodynamics and Environments (eds Benn, K., Mareschal, J. -C. & Condie, K. C.), pp. 149–75. American Geophysical Union, Washington D.C., Geophysical Monograph no. 164.
Nakamura, K., Morishita, T., Chang, Q., Neo, N. & Kumagai, H. 2007. Discovery of lanthanide tetrad effect in an oceanic plagiogranite from an ocean core complex at the Central Indian Ridge 25S. Geochemical Journal 41, 135–40.
Nutman, A. P., Bennett, V. C., Friend, C. R. L., Jenner, F., Wan, Y. & Liu, D. 2009. EoArchean crustal growth in west Greenland (Itsaq Gneiss Complex) and in north-eastern China (Anshan area): review and synthesis. In Earth Accretionary Systems in Space and Time (eds Cawood, P. A. & Kröner, A.), pp. 127–54. Geological Society of London, Special Publication no. 318.
Pearce, J. A. & Peate, D. W. 1995. Tectonic implications of the composition of volcanic arc magmas. Annual Review of Earth and Planetary Sciences 23, 251–85.
Qayyum, M., Niem, A. R. & Lawrence, R. D. 1996. Newly discovered Paleogene deltaic sequence in Katawaz Basin, Pakistan, and its tectonic implications. Geology 24, 835–8.
Rao, D. R., Rai, H. & Kumar, J. S. 2004. Origin of oceanic plagiogranite in the Nidar ophiolitic sequence of eastern Ladakh, India. Current Science 87, 9991005.
Rapp, R. P., Shimizu, N. & Norman, M. D. 2003. Growth of early continental crust by partial melting of eclogite. Nature 425, 605–9.
Robinson, P. T., Malpas, J., Dilek, Y. & Zhou, M. 2008. The significance of sheeted dike complexes in ophiolites. GSA Today 18, 410.
Rollinson, H. 2008. Ophiolitic trondhjemites: a possible analogue for Hadean felsic “crust.” Terra Nova 20, 364–69.
Rollinson, H. 2009. New models for the genesis of plagiogranites in the Oman Ophiolite. Lithos 112, 603–14.
Rollinson, H. 2014. Plagiogranites from the mantle section of the Oman Ophiolite: models for early crustal evolution. In Tectonic Evolution of the Oman Mountains (eds Rollinson, H. R., Searle, M. P., Abbasi, I. A., Al-Lazki, A. I. & Kindi, M. H. Al), pp. 247–61. Geological Society of London, Special Publication no. 392.
Samson, S. D., Inglis, J. D., D'Lemos, R. S., Admou, H., Blichert-Toft, J. & Hefferan, K. 2004. Geochronological, geochemical, and Nd-Hf isotopic constraints on the origin of Neoproterozoic plagiogranites in the Tasriwine Ophiolite, Anti-Atlas orogen, Morocco. Precambrian Research 135, 133–47.
Sawada, Y., Nagao, K., Siddiqui, R. H. & Khan, S. R. 1995. K-Ar ages of the Mesozoic igneous and metamorphic rocks from the Muslim Bagh area, Pakistan. Proceedings of Geoscience Colloquium 12, 7390.
Sen, C. & Dunn, T. 1994. Dehydration melting of a basaltic composition amphibolite at 1.5 and 2.0 GPa: implications for the origin of adakites. Contributions to Mineralogy and Petrology 117, 394409.
Shaw, D. M. 1970. Trace element fractionation during anatexis. Geochimica et Cosmochimica Acta 34, 237–43.
Siddiqui, R. H., Aziz, A., Mengal, J. M., Hoshino, K. & Sawada, Y. 1996. Geology, petrochemistry and tectonic evolution of the Muslim Bagh Ophiolite Complex, Pakistan. Proceedings of Geoscience Colloquium 16, 1146.
Siddiqui, R. H., Mengal, J. M., Hoshino, K., Sawada, Y. & Brohi, I. A. 2011. Back-arc basin signatures represented by the sheeted dykes from the Muslim Bagh Ophiolite Complex, Balochistan, Pakistan. Sindh University Research Journal 43, 5162.
Sun, S.-S. & McDonough, W. F. 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In Magmatism in the Ocean Basins (eds Saunders, A. D. & Norry, M. J.), pp. 313–45. Geological Society of London, Special Publication no. 42.
Tilton, G. R., Hopson, C. A. & Wright, J. E. 1981. Uranium-lead isotopic ages of the Samail Ophiolite, Oman, with applications to Tethyan Ocean ridge tectonics. Journal of Geophysical Research: Solid Earth 86, 2763–75.
Twining, K. 1996. Origin of plagiogranite in the Troodos ophiolite, Cyprus. In Proceedings of the 9th Keck Symposium in Geology, pp. 245–8. Williamstown, MA, 1 April 1996.
Wolf, M. B. & Wyllie, P. J. 1994. Dehydration-melting of amphibolite at 10 kbar: the effects of temperature and time. Contributions to Mineralogy and Petrology 115, 369–83.
Yaliniz, M. K., Floyd, P. A. & Goncuoglu, M. C. 2000. Petrology and geotectonic significance of plagiogranite from the Sarikaraman Ophiolite (Central Anatolia, Turkey). Ofioliti 1, 31–7.
Zhang, C., Holtz, F., Koepke, J., Wolff, P. E., Ma, C. & Bédard, J. H. 2013. Constraints from experimental melting of amphibolite on the depth of formation of garnet-rich restites, and implications for models of Early Archean crustal growth. Precambrian Research 231, 206–17.
Ziaja, K., Foley, S. F., White, R. W. & Buhre, S. 2014. Metamorphism and melting of picritic crust in the early Earth. Lithos 189, 173–84.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Geological Magazine
  • ISSN: 0016-7568
  • EISSN: 1469-5081
  • URL: /core/journals/geological-magazine
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Type Description Title
Supplementary materials

Cox et al. supplementary material
Tables S1-S3

 Word (30 KB)
30 KB
Supplementary materials

Cox et al. supplementary material
Figures S1-S3

 Word (644 KB)
644 KB


Full text views

Total number of HTML views: 5
Total number of PDF views: 46 *
Loading metrics...

Abstract views

Total abstract views: 209 *
Loading metrics...

* Views captured on Cambridge Core between 2nd April 2018 - 20th July 2018. This data will be updated every 24 hours.