A Ca. 2.25 Ga mafic dyke swarm discovered in the Bastar craton, Central India: Implications for a widespread plume-generated large Igneous Province (LIP) in the Indian shield

Highlights

• A new precise U–Pb baddeleyite ID-TIMS age (2251 ± 4 Ma) is obtained for an ENE-trending mafic dyke from the Bastar craton.

• The age of this new swarm closely matches with the ca. 2.26–2.25 Ga dykes in the Dharwar craton and the ca. 2.26 Ga dykes in the Singhbhum Craton.

• Together these three swarms define a ca. 2.26–2.25 Ga giant dyke swarm.

• Magmatic events of approximately similar age are known from the East Antarctica, Kaapvaal craton, and Zimbabwe craton.

Abstract

A precise U–Pb baddeleyite age (2251 ± 4 Ma) has been obtained for an ENE-trending dyke exposed near the Chhura region of the Bastar craton, and additional dykes of similar trend are also reported from other parts of the northern Bastar craton such as in the Dongergarh and Pakhanjore areas. We propose a new widespread ENE-trending ca. 2.25 Ga Chhura mafic dyke swarm in the Bastar craton, which represents a continuation of the NE- to ENE-trending ca. 2.26 Ga Kaptipada swarm in the Singhbhum craton. The adjoining Dharwar craton also hosts ca. 2.26–2.25 Ga magmatism, the N- to NNE-trending Ippaguda-Dhiburahalli dyke swarm. A geochemical match between the ca. 2.25 Ga Chhura, the ca. 2.26–2.25 Ga Ippaguda-Dhiburahalli, and most samples of the ca. 2.26 Ga Kaptipada swarms corroborates a genetic link. Together these mafic dykes in Bastar, Singhbhum and Dharwar cratons, define the ca. 2.26–2.25 Ga Ippaguda (-Dhiburahalli-Chhura-Kaptipada) LIP. The relative post-2.25 Ga rotations between the three cratons would allow two alternative locations for the plume centre either at the eastern end of the Kaptipada swarm in the Singhbhum craton or at the south end of the Ippaguda-Dhiburahalli swarm in the Dharwar craton. Alternatively, convergence of the Churra, Kaptipada and Ippaguda-Dhiburahalli sub-swarms could suggest a plume centre location in the Godavari rift, between the Bastar and Dharwar cratons. Magmatic events of approximately this 2.26–2.25 Ga age are known from other parts of the globe including East Antarctica, and Kaapvaal and Zimbabwe cratons.

Introduction

Identification, dating and determination of the extent of a Large Igneous Province (LIP) plays an important role in reconstructing ancient supercratons and supercontinents (e.g., Bleeker, 2003, Ernst and Bleeker, 2010, Ernst et al., 2017, Ernst et al., 2019). Typically, a LIP is a short duration (<5 Myr; although longer durations are possible) intraplate mafic-ultramafic voluminous (>0.1 Mkm³) magmatic event that occurs in both continental and oceanic tectonic regimes (e.g., Coffin and Eldholm, 1994, Bleeker and Ernst, 2006, Bryan and Ernst, 2008, Bryan and Ferrari, 2013, Ernst, 2014, Ernst et al., 2019).

The LIP record in the Phanerozoic is expressed as continental flood basalts or oceanic plateaus, such as the Deccan Igneous Province, the Siberian Traps, the Ontong Java oceanic plateau, etc. (e.g., Jay and Widdowson, 2008, Ernst, 2014). However, in the Precambrian, the flood basalt component has typically been removed by erosion, thereby exposing the plumbing system components, such as mafic dyke swarms, sill provinces, mafic-ultramafic layered intrusions, and a lower crustal magmatic underplate (e.g., Ernst and Buchan, 2001, Ernst, 2014, Richards et al., 2015, Ernst et al., 2019). Due to their great vertical extent (potentially 10 s of km) and lateral extent (>300 km and often >1000 km), mafic dyke swarms in cratonic areas are considered to be the best-preserved record of Precambrian LIPs (e.g., Fahrig, 1987, Halls and Fahrig, 1987, Parker et al., 1990, Baer and Heimann, 1995, Ernst and Buchan, 2001, Hanski et al., 2006, Bleeker and Ernst, 2006, Srivastava et al., 2010, Srivastava et al., 2019a, Srivastava, 2011, Ernst, 2014). Significantly, mafic dyke swarms (with giant radiating, circumferential and linear geometries) play (Samal et al., 2021a) a key role in locating mantle plume centres, and reconstructing ancient supercontinents (e.g., Ernst and Buchan, 1997, Bleeker, 2004, Ernst et al., 2010, Ernst, 2014, Buchan and Ernst, 2021). Mantle plumes play an important role in the genesis of LIPs (e.g., Campbell and Griffiths, 1990, Kerr et al., 2000, Courtillot et al., 2003, Ernst and Buchan, 2003, Campbell, 2005, Pirajno, 2007, Campbell and Kerr, 2007, Torsvik et al., 2010, Sobolev et al., 2011, Ernst, 2014, Ernst et al., 2019), although non-plume models are also proposed (such as rift-related decompression melting, lithospheric delamination, thermal blanketing during a supercontinent, edge convection, etc.) (e.g., White and McKenzie, 1989, Anderson, 1998, Sheth, 1999, Elkins-Tanton and Hager, 2000, Foulger, 2002, Ingle and Coffin, 2004, Ernst et al., 2005, Ernst, 2014, Klausen, 2020).

Here, we present a new U-Pb baddeleyite ID-TIMS age for a ENE-trending mafic dyke swarm of the Bastar craton, central India (see Fig. 1, Fig. 2). The Bastar craton is traversed by multiple distinct sets of Neoarchean-Mesoproterozoic mafic dykes trending in different directions (cf. Srivastava and Singh, 2004, French et al., 2008, Srivastava and Gautam, 2015, Srivastava et al., 2016). On the basis of field, geochemical (cf. Srivastava and Singh, 2004, Srivastava and Gautam, 2012, Srivastava and Gautam, 2015, Srivastava et al., 2016 and references therein), and geochronological (French et al., 2008, Ratre et al., 2010, Srivastava et al., 2009, Srivastava et al., 2011, Srivastava et al., 2014, Das et al., 2011, Pisarevsky et al., 2013, Shellnutt et al., 2018, Shellnutt et al., 2019, Liao et al., 2019, Pandey et al., 2020a) data, Samal et al., 2019a, Samal et al., 2019b, Pandey et al., 2020a, we have identified seven distinct mafic dyke swarms from the Bastar craton each potentially linked to a LIP event (see Fig. 2); these include the WNW- to NW-trending ca. 2.7 Ga Sukma linear swarm; NW-trending ca. 2.50 Ga Dantewara linear swarm; NW-trending ca. 2.37 Ga Bhanuprtappur linear swarm; NW and NNW- to N-trending ca. 1.89–1.88 Ga Bastanar radiating swarm; NNW- to NW-trending ca. 1.85 Ga Sonakhan swarm; N- to NNE-trending ca. 1.46–1.44 Ga Lakhna linear swarm; and ENE-trending ca. 1.42 Ga Bandalimal linear swarm. In addition, NW-trending mafic dykes exposed in the southern region have a preliminary U-Pb age of ca. 1.78 Ga (Srivastava et al., 2000, Srivastava and Singh, 2003) and are labelled the Geedam swarm (Srivastava et al., 2021, MS submitted to the Geol. Soc. London Spl. Issue 518). A few additional intra-plate magmatic events are also recorded from the Bastar craton, which could also be clues to additional large intraplate events, potentially of LIP scale; examples include (i) ca. 2.47 Ga syenite intrusion (Santosh et al., 2018), which can be linked to the ca. 2.50–2.47 Ga Dantewara LIP (Samal et al., 2019a, Samal et al., 2021a); (ii) ca. 2.18 Ga Bijli rhyolites (Divakara Rao et al., 2000), potentially part of a silicic LIP that could be linked to the ca. 2.18 Mahbubnagar-Dandeli swarm of the Dharwar craton (Samal et al., 2019a); and (iii) ca. 1.10–1.05 Ga lamproite-kimberlite intrusions (Sahu et al., 2013, Chalapathi Rao et al., 2014, Chalapathi Rao et al., 2016), potentially linked to the 1110 Ma LIP of the Bundelkhand craton and other blocks (e.g., Choudhary et al., 2019).

Discovery of a new swarm, the ENE-trending 2251 ± 4 Ma Chhura swarm (this study) adds another mafic magmatic event in the Bastar craton, which can be matched with other coeval swarms in the Singhbhum and Dharwar cratons. The expanded LIP barcode of the Bastar craton (and matching with the barcode record of other parts of India) provides insights into possible locations for a 2250 Ma plume centre, and constraints on the reconstruction of the Indian cratons in ancient supercontinents.