Journal of the Geological Society of India

, Volume 87, Issue 1, pp 35–42 | Cite as

Hybrid mafic dykes from Delwara Shear Zone, Mt. Abu, NW India

  • Manoj K. PanditEmail author
  • Ramona Dotzler
  • Helga De Wall
Research Articles


Mafic dykes intrude the composite Mt. Abu granite batholith as a minor and the last phase of magmatism. The dykes are sub-vertical, variable in width and visibly compact, however, features of alteration and shearing can be seen. The dykes occurring within the recently identified and described, Delwara Shear Zone (DWSZ), from the western margin of the Mt. Abu batholith are intensely to moderately sheared and intricately mixed with the host granitoids. The mafic dykes occurring within the shear zone bear evidence of assimilating the host granitoids during their ascent, seen as relicts, streaks and sub-rounded K-feldspar clasts in mafic dykes. The hybridization has resulted in unusual geochemical signatures of the mafic dykes such as higher silica levels, erratic and high incompatible trace element abundances and lack of any systematic trends. Mixing line calculations on the mafic dyke samples reveal between 30 to 60% felsic input into the mafic dykes. Mafic dykes outside the shear zone in the Mt. Abu are meter scale in width and generally free of felsic inclusions owing to small volumes of mafic melts. Large volume of mafic melts are required for assimilating up to 60% felsic component which has been identified as approximately 100 m wide zone within the DWSZ. Shearing has played an important role in providing the channel ways and for sustained high temperatures to allow such hybridization.


Mafic dykes Delwara Shear Zone Geochemistry Hybridization Mixing line calculation Mt. Abu Rajasthan 


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  1. Ashwal, L.D., Solanki, A.M., Pandit, M.K., Corfu, F., Hendriks, B.W.H., Burke, K. and Torsvik, T.H. (2013) Geochronology and geochemistry of Neoproterozoic Mt. Abu Granitoids, NW India: Regional correlation and implications on Rodinia paleogeography. Precambrian Res., v. 236, pp. 265–281.CrossRefGoogle Scholar
  2. BRÄTZ, H. and Klemd, R. (2002) Analysis of Rare Earth Elements in Geological Samples by Laser ablation–Inductively Coupled Plasma Mass Spectroscopy (LA-Icp-MS). Agilent Technologies Online Publ. No.6.Google Scholar
  3. Bhushan, S.K. and Chandrasekaran, V. (2002) Geology and geochemistry of the magmatic rocks of the Malani Igneous Suite and Tertiary Volcanic Province of western Rajasthan. Mem. Geol. Surv. India, v.126, 179p.Google Scholar
  4. Castro, A., DE LA Rosa, J. and Stephens, W. (1990) Magma mixing in the subvolcanic environment: petrology of the Gerena interaction zone near Seville, Spain. Contrib. Mineral. Petrol., v.106, pp.9–26.Google Scholar
  5. Choudhary A.K., Gopalan, K. and Sastry, C.A. (1984) Present status of the geochronology of Precambrian rocks of Rajasthan. Tectonophysics, v.105, pp.131–140.CrossRefGoogle Scholar
  6. DE Wall, H., Pandit, M.K., Dotzler, R. and Just, J. (2012) Cryogenian transpression and granite intrusion along the western margin of Rodinia (Mt. Abu region): Magnetic fabric and geochemical inferences on Neoproterozoic geodynamics of the NW Indian block. Tectonophysics, v.554-557, pp.143–158.CrossRefGoogle Scholar
  7. DE Wall, H., SchÖBel, S., Pandit, M.K., Sharma, K.K. and Just, J. (2010) A record of ductile syn-intrusional fabrics to post solidification cataclasis: Magnetic fabric analyses of Neoproterozoic Mirpur and Mt. Abu Granitoids, NW India. Jour. Geol. Soc. India, v.75, pp.239–253.CrossRefGoogle Scholar
  8. DE Wall, H., Pandit, M.K., Sharma, K.K., SchÖBel, S., and Just, J. (2014) Deformation and granite intrusion in the Sirohi area, SW Rajasthan-Constraints on Cryogenian to Pan-African crustal dynamics of NW India. Precambrian Res., v.254, pp.1–18.CrossRefGoogle Scholar
  9. Deb, M., Thorpe, R.I., Krstic, D., Corfu, F. and Davis, D.W. (2001) Zircon U-Pb and galena Pb isotope evidence for an approximate 1.0 Ga terrane constituting the western margin of the Aravalli-Delhi orogenic belt, northwestern India. Precambrian Res., v.108, pp.195–213.CrossRefGoogle Scholar
  10. Gregory, L.C., Meert, J.G., Bingen, B., Pandit, M.K. and Torsvik, T.H. (2009) Paleomagnetism and geochronology of the Malani Igneous Suite, northwest India: implications for the configuration of Rodinia and assembly of Gondwana. Precambrian Res., v.170, pp.13–26.CrossRefGoogle Scholar
  11. Gupta, S.N., Arora, Y.K., Mathur, R.K., Iqballuddin Prasad, B., Sahai, T.N. and Sharma, S.B. (1997) The Precambrian Geology of the Aravalli Region, Southern Rajasthan and Northeastern Gujarat. Mem. Geol. Surv. India, v.123, 262p.Google Scholar
  12. Heron, A.M. (1953) Geology of Central Rajputana. Mem. Geol. Surv. India, v.79, 339p.Google Scholar
  13. Just, J., Schulz, B., DE Wall, H., Jourdan F. and Pandit, M.K. (2011) Emp monazite dating of granitoid deformation: implications for Neoproterozoic ductile shear zone tectonics to the west of the Delhi Fold Belt, Gondwana Res., v.19, pp.402–412.CrossRefGoogle Scholar
  14. Meert, J.G., Pandit, M.K. and Kamenov, G.D. (2013) Further geochronological and paleomagnetic constraints on Malani (and Pre-Malani) magmatism in NW India. Tectonophysics, v. 608, pp. 1254–1267.CrossRefGoogle Scholar
  15. Pandit, M.K., Carter, L.M., Ashwal, L.D., Tucker, R.D., Torsvik, T.H., Jamtveit, B. and Bhushan, S.K. (2003) Age, petrogenesis and significance of 1 Ga granitoids and related rocks from the Sendra area, Aravalli Craton, NW India. Jour. Asian Earth Sci., v.22, pp.363–381.CrossRefGoogle Scholar
  16. Pandit, M. K., Shekhawat, L.S., Ferreira, V. P., Sial, A. N. and Bohra, S.K. (1999) Trondhjemite and granodiorite assemblages from west of Barmer: probable basement for Malani magmatism in western India. Jour. Geol. Soc. India, v.53, pp.89–96.Google Scholar
  17. Pradhan, V.R., Meert, J.G., Pandit, M.K., Kamenova George, Gregory, L.C. and Malone, S.J. (2010) India’s changing place in global Proterozoic reconstructions: A review of geochronologic constraints and paleomagnetic poles from the Dharwar, Bundelkhand and Marwar cratons. Jour. Geodynamics, v.50, pp.224–242.CrossRefGoogle Scholar
  18. Singh, B.N. (2007) Petrology and Geochemistry of the Mount Abu Granites, Southwestern Rajasthan. Jour. Geol. Soc. India, v.69, pp.247–252.Google Scholar
  19. Singh, B.N. and Joshi, M. (2005) Occurrence of rhyolitic dykes within the Mt. Abu batholith, southwestern Rajasthan. Jour. Geol. Soc. India, v.65, pp.309–316.Google Scholar
  20. Sun, S-s. and Mcdonnough, W.F. (1989) Chemical and isotopic systematics of ocean basalts: implications for mantle composition and processes. In: A.D. Saunders and M.J. Norry (Eds.), Magmatism in the Ocean Basins. Geol. Soc. London Spec. Publ., v.42, pp.313–345.CrossRefGoogle Scholar
  21. Torres-Alvarado, I. S., Verma S. P., Palacios-Berruete, H., Guevara, M. and González-Castillo, O.Y. (2003) DC_Base: a database system to manage Nernst distribution coefficients and its application to partial melting modelling. Computer Geoscience, v.29, pp.1191–1198CrossRefGoogle Scholar
  22. Torsvik, T.H., Carter, L.M., Ashwal, L.D., Bhushan, S.K., Pandit, M.K. and Jamtveit, B. (2001) Rodinia refined or obscured: Palaeomagnetism of the Malani Igneous Suite (NW India). Precambrian Res., v.108, pp.319–333.CrossRefGoogle Scholar
  23. Van Lente, B., Ashwal, L.D., Pandit, M.K., Bowring, S.A. and Torsvik, T.H. (2009) Neoproterozoic hydrothermally altered basaltic rocks from Rajasthan, northwest India: implications for late Precambrian tectonic evolution of the Aravalli craton. Precambrian Res., v.170, pp.202–222.CrossRefGoogle Scholar
  24. Wilson, M. (1989) Igneous Petrogenesis. Unwyn Hyman, London, 466p.CrossRefGoogle Scholar

Copyright information

© Geological Society of India 2016

Authors and Affiliations

  • Manoj K. Pandit
    • 1
    Email author
  • Ramona Dotzler
    • 2
  • Helga De Wall
    • 3
  1. 1.Department of GeologyUniversity of RajasthanJaipurIndia
  2. 2.Baker Hughes Norge ASStavangerNorway
  3. 3.Geozentrum NordbayernUniversitat Erlangen-NürnbergErlangenGermany

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