Elsevier

Journal of Asian Earth Sciences

Volume 50, 2 May 2012, Pages 128-140
Journal of Asian Earth Sciences

Origin and serpentinization of ultramafic rocks of Manipur Ophiolite Complex in the Indo-Myanmar subduction zone, Northeast India

https://doi.org/10.1016/j.jseaes.2012.01.004Get rights and content

Abstract

The Manipur Ophiolite Complex (MOC) is part of the Manipur-Nagaland ophiolite belt (MNOB). The belt is exposed in the eastern margin of the Indo-Myanmar Ranges (IMRs), which formed by the collision between the India and Myanmar continental plates. Several contrasting views were put forward concerning the origin of the MNOB. The complex represents a dismembered ophiolite sequence with serpentinite as the largest litho-unit formed. Petrography and Raman spectroscopy of the serpentinite suggest that they are serpentinized ultramafic cumulate and peridotite. The serpentinization may have occurred at a condition of low pressure and low temperature metamorphism. Geochemical signatures of the rocks and spinel grains revealed that the protolith be an abyssal peridotite, derived from a less depleted fertile mantle melt at a MORB setting after low degree (10–15%) partial melting. The study concluded that the serpentinite may have been created at a slow-spreading ridge, rather than a supra-subduction-zone setting. These rocks were later obducted and incorporated into the IMR of Indo-Myanmar suture zone.

Highlights

Ultramafic rocks are serpentinized in low P-T conditions. ► The protoliths were abyssal peridotite, derived from less depleted mantle melt. ► They are originated at an MORB setting after low degree (10–15%) partial melting. ► Serpentinite may have created at slow-spreading ridges, rather than a SSZ setting. ► We develop a model of origin and tectonic evolution of the Indo-Myanmar Ranges.

Introduction

The closure of the Tethyan oceanic realm during the Late Cretaceous and Early Tertiary preserved many ophiolite complexes within the Indo-Myanmar-Australia suture zones (Mitchell, 1981), including the MNOB in the Indo-Myanmar suture zone (Acharyya, 2007, Singh, 2008). The ophiolites, including serpentinite of the belt were derived from tectonic activities developed in the Tethyan oceanic lithosphere due to subduction of Indian plate below the Eurasian plate (Nandy, 1981, Oldham, 1883, Brunnschweiler, 1966).

The MOC is confined within the eastern sector of the IMRS (Vidyadharan et al., 1989, Singh, 2008). The complex is a dismembered ophiolite sequence with development of a mélange zone and an olistostromal plate margin (Evans, 1964, Vidyadharan et al., 1989). Well-preserved mantle sequences occur in the ophiolite belt (Acharyya, 1986, Ghose et al., 1986, Vidyadharan et al., 1989). However, the occurrence of serpentinite is observed as the most voluminous litho-tectonic unit in the complex. Pelagic sediments, pillow basalts, volcanic rocks, mafic dyke rocks and podiform chromitites are also exposed in minor in the complex. Rare occurrences of gabbros are observed in the study area.

Several contrasting views were put forward concerning the origin of the MNOB. One school of thought believed that the belt originated from multiple subduction processes of the Indian plate beneath the Eurasian Plate (Mitchell, 1993, Acharyya, 2007). Another school believed that the MNOB is rootless sub-horizontal bodies, which are westward-propagated nappes from the Eastern Belt Ophiolite of Myanmar (Sengupta et al., 1990, Acharyya et al., 1990). Another theory also believed that the belt originated in an Island Arc developed in the Tethyn Ocean (Bhattacharjee, 1991, Nandy, 2001). Furthermore, due to remote and inaccessible nature of the terrain, very less research work has been done in the area. An understanding of the origin of the MOC serpentinite is significant in evaluating the tectonic evolution of the subduction zone. A combination of petrological and geochemical studies of serpentinite can assist in determining the origin and geodynamic settings of serpentinization (Auzende et al., 2002, Hattori and Guillot, 2007, Saumur et al., 2010, Monsef et al., 2010). Raman spectroscopy can be used to study serpentine and the serpentinization processes (Kloprogge et al., 1999, Rinaudo et al., 2003, Auzende et al., 2004, Groppo et al., 2006). This paper details the origin and serpentinization of ultramafic rocks of the MOC through a combined effort of petrology and geochemical analysis. Origin and evolution of the MOC serpentinites, and in consequence, model of subduction of the Indian Plate and Myanmar Plate is discussed.

Section snippets

Geology and field setting

The MOC is located in the MNOB, which is confined within the eastern sector of the IMRs (Fig. 1). The belt constitutes a part of the Arakan-Yoma Fold Belt separating Northeastern India from Myanmar (Nandy, 1981). The belt forms a NNE–SSW trending linear tract with a length of about 200 km and has an average width of about 15 km. The IMR are mainly composed of the Late Cretaceous–Paleogene marine sedimentary rocks, unconformably overlying the Upper Triassic flysch-type sedimentary rocks and

Sampling and analytical methods

Serpentinite samples with various degrees of serpentinization were collected from different locations of the MOC (Fig. 1B). Detailed petrographic studies of the selected thin section slides were carried out at the Department of Geology, Centre for Advanced Studies, University of Delhi. Leica Workstation DMRX with the image analysis system was used to analyze the types of serpentine minerals present in ultramafic rocks.

Raman spectroscopy of samples was done at the Ecole Normale Superieure of

Partially serpentinized peridotite

Most of the peridotites of MOC are highly serpentinized, but few are partially serpentinized. Relicts of harzburgite and lehrzolite frequently occur in the less serpentinized samples of the complex (Fig. 4A1). Wehrlite, dunite and pyroxenite are relatively infrequent as relict in the samples while websterite is absent. The presence of two generations of pyroxenes (orthopyroxene and clinopyroxene), with inclusion of olivine in both pyroxene grains are observed in most of the partially

Source and origin of serpentinite

AFM and ACF ternary plots of the serpentinite samples of MOC inferred that the samples belong to a combined field of metamorphic peridotite and ultramafic cumulates. Higher average value of Al2O3 (2.66 wt.%) in the samples reflects a higher proportion of clinopyroxene phase than that of normal ophiolitic harzburgite and dunite, so the source of the samples is more fertile (Coleman, 1971). The nearly flat pattern of chondrite normalized REE, also indicates that the source of rocks is from a

Conclusions

There is much confusion regarding the origin of the MNOB. This study focusing on petrology and geochemistry of the serpentinite component of the MOC helps clarify its tectonic setting. Our research work concluded that, even though the MOC serpentinites are exposed in the Indo-Myanmar subduction zone, they were originated at a spreading regime (MORB setting) due to the low degree partial melting (10–15°) of a less depleted, fertile mantle melt. Subsequently, the ultramafic rocks were

Acknowledgements

Ningthoujam would like to thank UGC-CAS for providing fellowship for Ph. D. and R&D-DU for providing funds for this research work. We are indebted to the Prof. An Yin and Prof. Kéiko H. Hattori, for reviewing and giving constructive comments that greatly improved the manuscript. We are also thankful to Dr. Sandeep for providing facilities for ICP-MS. Thanks are due to Prof. Soibam Ibotombi, Manipur University for guiding us during our field work.

References (65)

  • H. Paulick et al.

    Geochemistry of abyssal peridotites (Mid-Atlantic Ridge, 15o20’N, ODP Leg 209): Implication for fluid/rock interaction in slow spreading environments

    Chemical Geology

    (2006)
  • R.J. Stern et al.

    The source of the subduction component in convergent margin magmas: trace element and radiogenic evidence from Eocene boninites, Mariana forearc

    Geochemica at Cosmochimica Acta

    (1991)
  • E. Stolper et al.

    The role of water in the petrogenesis of Mariana trough magmas

    Earth and Planetary Science Letters

    (1994)
  • B. Wunder et al.

    Antigorite; high pressure stability in the system MgO–SiO2–H2O (MSH)

    Lithos

    (1997)
  • S.K. Acharyya

    Tectono-stratigraphic history of Naga Hills Ophiolites

    Geological Survey of India Memoirs

    (1986)
  • Acharyya, S.K., Ray, K.K., Sengupta, S., 1990. Tectonics of ophiolite belt from Naga Hills and Andaman Islands, India....
  • Agarwal, O. P., Kacker, R.N., 1979. Nagaland ophiolite, India: A subduction zone ophiolite complex in Tethyan orogenic...
  • J.F. Allen et al.

    Cr-spinels as petrogenetic indicators: MORB-type lavas from the Lamount seamount chain, eastern Pacific

    American Mineralogist

    (1988)
  • A.-L. Auzende et al.

    Serpentinites from Central Cuba: petrology and HRTEM study

    European Journal of Mineralogy

    (2002)
  • A.-L. Auzende et al.

    High-pressure behavior of serpentine minerals: a Raman spectroscopic study

    Physics Chemistry of Minerals

    (2004)
  • Bouchet, A., 2008. Characterization of serpentine present in the Oligocene conglomerates and Miocene syn-orogenic...
  • R.O. Brunnschweiler

    On the geology of the Indo-Burma Ranges

    Geological Society of Australia

    (1966)
  • B.M. Chattopadhyay et al.

    Geology of Naga Hills Ophiolites

    Records Geological Survey of India

    (1983)
  • P. Chungkham et al.

    Late Cretaceous (Santonian–Maastrichtian) integrated Coccolith–Globotruncanid biostratigraphy of pelagic limestone from the accretionary prism of Manipur, Northeastern India

    Micropalaeontology

    (1998)
  • R.G. Coleman

    Petrologic and geophysical nature of serpentinites

    Geological Society of America, Bulletin

    (1971)
  • R.G. Coleman

    Ophiolites-Ancient Oceanic Lithosphere

    (1977)
  • H.J.B. Dick et al.

    Cr-spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas

    Contributions to Mineralogy and Petrology

    (1984)
  • P. Evans

    Explanatory notes to accompany a table showing the tertiary succession in Assam: Trans

    Mining and Geology International, India

    (1932)
  • P. Evans

    The tectonic framework of Assam

    Journal Geological Society of India

    (1964)
  • B. Evans

    The serpentinite multisystem revisited: Chrysotile is metastable

    International Geological Review

    (2004)
  • Geological Survey of India, 1987. Geological map of Manipur, M.N.C. DRG....
  • N.C. Ghose et al.

    Geochemistry of the ophiolite belt of Nagaland, N.E. India, ophiolite and Indian plate margin

  • Cited by (59)

    • Resurfacing of deeply buried oceanic crust in Naga Hills Ophiolite, North-East India: Petrofabric, microstructure and seismic properties

      2020, Journal of Structural Geology
      Citation Excerpt :

      The NHO consists of tectonized dismembered bodies of serpentinized lherzolite and harzburgite with minor dunite, wehrlite and pyroxenite. Mafic volcanic rocks occur in close association with chert, marl, plagiogranite and mafic cumulates (olivine-gabbro, gabbro, oxide-gabbro) (Roy and Kacker, 1980; Mitra et al., 1986; Ningthoujam et al., 2012; Abdullah et al., 2018). The NHO is overlain by Mid-Eocene coarse clastic ophiolite derived sedimentary cover.

    • X-ray synchrotron microtomography: a new technique for characterizing chrysotile asbestos

      2020, Science of the Total Environment
      Citation Excerpt :

      All seven specimens are characterized by the presence of veins that crosscut the serpentinite rock and often intersect each other (Fig. 2a–f). The veins did not seem to possess a preferred texture or orientation thus suggesting that they formed under different mechanisms and conditions of formation (Ningthoujam et al., 2012). This is probably due to the effects that different stages of serpentinization had on the ultramafic protolith, from fracture network development to vein infill (Andréani et al., 2004; Evans, 2004).

    View all citing articles on Scopus
    View full text