Geochemistry of ultramafic–mafic rocks of the Madawara Ultramafic Complex in the southern part of the Bundelkhand Craton, Central Indian Shield: Implications for mantle sources and geodynamic setting

Abstract

Detailed field, petrography and whole‐rock geochemical study was carried out in order to constrain the mantle sources and geodynamic setting of the Madawara Ultramafic Complex (MUC) of the Bundelkhand Craton. Studies reveal that there are two types of ultramafic rocks: (a) high‐Mg ultrabasic/basic rocks and (b) undeformed ultramafic–mafic plutonic rocks. The high‐Mg ultrabasic/basic rocks have undergone severe low‐grade (greenschist) metamorphism and are characterized by stringer and veinlet structures of talc–tremolite–actinolite schists with alternate layers of serpentinites showing comparatively higher SiO2 (46.1–49.4 wt%), lower MgO (24.6–26.2 wt%), and higher Al2O3 (4.58–7.06 wt%) and CaO (2.72–6.77 wt%) compared to the undeformed ultramafic rocks. The undeformed ultramafic rocks (mainly harzburgite, lherzolite, and olivine websterite) are characterized by globular structures and have lower SiO2 (40–44.1 wt%), higher MgO (30.4–38 wt%) and lower Al2O3 (1.84–4.03 wt%) and CaO (0.16–3.14 wt%). The undeformed mafic rocks (mainly gabbro) occur as small pockets within the undeformed ultramafic rocks as well as independent outcrops. Limited variation in Nb/Th against Nb/Yb along with negative Nb‐Ti anomalies of all the rock types in the multi‐element diagram reveals the significant role of the metasomatized mantle in their genesis. All the rocks show enrichment in light rare earth element and large‐ion lithophile elements compared to heavy rare earth elements and high‐field strength elements. The geochemical characteristics coupled with Ce/Yb versus Ce variation of the rocks of MUC point towards two different sources for their genesis. The high‐Mg ultrabasic/basic rocks are derived from partial melting of metasomatized mantle at shallow depth, while the undeformed ultramafic rocks were formed as a result of asthenospheric upwelling from a greater depth that induced the melting in the overlying lithosphere. Gabbro rocks represent the last and most evolved phase of the complex. Geochemical signatures suggest that the rocks of MUC were formed in a continental arc setting.

Evolution of Bundelkhand Craton

“…About 400 m thick low-lying ridge is the largest outcrop of ultramafic exposed in the south east of Madawara Village (Mohanty et al, 2018). The rocks of this complex are mainly confined between the Madawara Shear in north and the Sonrai-Girar Shear in south and have undergone greenschist to lower amphibolites facies metamorphism Satyanarayanan et al, 2014;Ramiz et al, 2018). The whole sequence of mafic-ultramafic rocks of this complex is cut across by dolerite dykes .…”

“…The MUC lies at the southern fringe of BuC and has been established as a potential source for platinum group elements (PGEs) in north central India Farooqui and Singh, 2006;Prakash et al, 2009;Farooqui and Singh, 2010;Singh et al, 2011;Balaram et al, 2013;Satyanarayanan et al, 2010Satyanarayanan et al, , 2014Satyanarayanan et al, , 2015Singh et al, 2018). Here, variously altered and metamorphosed (± deformed) mafic and ultramafic rocks (metadunite, metaperidotite (± hornblende), metapyroxenite (± olivine), gabbro and diorite) occur as ~E-W-trending lensoidal bodies, distributed in about 400 sq km area and are togetherly, known as MUC Farooqui and Singh, 2006;Singh et al, 2011;Satyanarayanan et al, 2014;Mohanty et al, 2018;Ramiz et al, 2018;Singh et al, 2018). An integration of field, petrography and bulk rock geochemistry have been carried out in MUC to understand its petrogenesis and tectonic setting (Mohanty et al, 2018;Ramiz et al, 2018).…”

“…Here, variously altered and metamorphosed (± deformed) mafic and ultramafic rocks (metadunite, metaperidotite (± hornblende), metapyroxenite (± olivine), gabbro and diorite) occur as ~E-W-trending lensoidal bodies, distributed in about 400 sq km area and are togetherly, known as MUC Farooqui and Singh, 2006;Singh et al, 2011;Satyanarayanan et al, 2014;Mohanty et al, 2018;Ramiz et al, 2018;Singh et al, 2018). An integration of field, petrography and bulk rock geochemistry have been carried out in MUC to understand its petrogenesis and tectonic setting (Mohanty et al, 2018;Ramiz et al, 2018). About 400 m thick low-lying ridge is the largest outcrop of ultramafic exposed in the south east of Madawara Village (Mohanty et al, 2018).…”

“…In general, the contacts between ultramafic rocks and Bundelkhand granite-gneisses are sheard and mylonitized in the area Ramiz et al, 2018). Recent geochemical studies have shown that rocks of this region are enriched in light rare earth elements (LREEs) and LILEs as compared to HREEs and HFSEs favouring the continental arc setting for the MUC (Mohanty et al, 2018;Ramiz et al, 2018). However, Satyanarayanan et al (2015) have reported that the MUC are depleted in Cu, Al, Ca and V.…”

Petrology and geochemistry of metamorphosed rocks associated with iron formations of the Toko‐Nlokeng iron deposit, (Southern Cameroon): Implications for geodynamic evolution and mineralization

“…The destruction of the old crust over time is because of either the progressive accumulation of new crust or the tectonic recycling of the old crust (e.g., Singh et al, 2016; Yang et al, 2014; Zhang et al, 2013). The mafic‐ultramafic rocks play a very important role as they contain many metal deposits (e.g., Ma et al, 2016; Ramiz et al, 2018; Zhang et al, 2021), particularly gold, nickel, chromium, cobalt, copper, iron, platinum group elements (PGE), and volcanogenic massive sulphide (VMS) deposits and diamond deposits worldwide (e.g., Ebah Abeng et al, 2012; Kepezhinskas et al, 2016; Singh et al, 2016; Song et al, 2011; Song & Li, 2009; Zhang et al, 2021; Zhou, 1994). Brahmaiah et al (2017) stated that the mafic‐ultramafic rocks are characterized by their holomelonocratic nature.…”