Neoarchaean and Proterozoic crustal growth and reworking in the Western Bastar Craton, Central India: Constraints from zircon, monazite geochronology and whole-rock geochemistry
Introduction
The Mesoarchean to Neoarchean period is of particular interest as the Earth may have transitioned from a stagnant lid to a plate tectonic regime during this time (e.g., (Cawood et al., 2018). Many Archean cratons have witnessed extensive granitoid magmatism in the Mesoarchean-Neoarchean, especially around the Archean-Proterozoic transition (Condie and Kröner, 2012, Wang et al., 2016). The Archean-Proterozoic boundary is considered to mark a significant change in geothermal and tectonic regime of continental crust formation (Teixeira and Figueiredo, 1991).
Therefore, granitoids from this period can provide vital clues for understanding continental crust formation and growth during this important phase in the Earth’s geological history (Cawood et al., 2018).
The Indian shield is an amalgam of five major Archean cratonic nuclei, i.e., Bastar, Dharwar, Singhbhum, Bundelkhand, and Aravalli that constituted two crustal blocks, the northern and southern blocks. The Aravalli and Bundelkhand cratons comprised the northern Indian block, while the Dharwar, Bastar, and Singhbhum cratons were a part of the southern Indian block. The northern and southern crustal blocks are thought to have amalgamated during the Proterozoic along the Central Indian Tectonic Zone (CITZ), forming the greater Indian landmass Radhakrishna and Naqvi, 1986, Naqvi and Rogers, 1987, Chakraborty et al., 2019, Bhowmik, 2019 and references therein) (Fig. 1a).
The Archean cratons of India record protracted continental crust formation and reworking from the Hadean to the Paleoproterozoic (Upadhyay et al., 2014, Upadhyay et al., 2019, Manikyamba et al., 2017, Jayananda et al., 2018, Chaudhuri et al., 2018, Mondal et al., 2019, Santosh et al., 2020, Ranjan et al., 2020a, Ranjan et al., 2020b). Most of them have witnessed extensive crustal growth/reworking from the Paleoarchean to the Neoarchean and were therefore likely to have participated in the Ur supercontinent that is thought to have existed between ~ 3.0 Ga and 2.5 Ga period (Rogers, 1993, Rogers and Santosh, 2003). Mesoarchean (~3.0 Ga) granitoid crust is well-documented in the Singhbhum, Bastar, Dharwar, Kaapvaal, and Yilgarn cratons (Rogers, 1986, Nelson et al., 1999, Mahapatro et al., 2012, Saha et al., 2016 and references therein); similarly, extensive occurrences of Neoarchean granitoids have also been reported from all cratons of India, except the Singhbhum Craton (Radhakrishna and Naqvi, 1986, Upadhyay et al., 2014, Mondal et al., 2002, Verma et al., 2016), supporting the inclusion of these cratonic nuclei in the Ur- supercontinent.
The Bastar Craton in central India consists dominantly of Archaean granitoids. The pioneering work by Crookshank (1963), who mapped the southern part of the craton, classified the rock suites into three stratigraphic successions. Subsequently, a number of studies have looked at different aspects of the Bastar Craton including tectonics, structure, sedimentation, magmatism, metamorphism, geochemistry, metallogeny, and geochronology (Sarkar et al., 1993, Hussain et al., 2004, Stein et al., 2004, Mondal et al., 2006, Mondal et al., 2019, Rajesh et al., 2009, Mohanty, 2015, Manikyamba et al., 2016, Khanna et al., 2018, Dora et al., 2020, Santosh et al., 2020, Meshram et al., 2021, Srivastava et al., 2021).
However, Neoarchean TTGs and sanukitoids and Paleo-Mesoproterozoic granites from the Western Bastar Craton (WBC), are in general poorly studies in spite of constituting crucial components of the continental crust. No comprehensive work has been carried out on the mineralogy, geochemistry and geochronology of these granitoids and their role in the evolution of the Bastar Craton is poorly understood. The position of the WBC in the framework of the Ur or expanded Ur supercontinent is therefore not fully understood.
This study discusses whole-rock geochemistry and U-Th-Pb zircon/monazite ages of Neoarchean TTGs/sanukitoids and Paleo to Mesoproterozoic juvenile granites from the WBC. We also present Nd isotope data and model age for mafic enclaves present within the TTGs. Based on these data, we discuss Neoarchean to Paleo-Mesoproterozoic crustal evolution and geodynamic processes in the WBC and their link with other Archean cratons that may been a part of ancient supercontinent assemblies.
The Bastar Craton covering approximately 2,15,000 km2, is a square crustal block in central India, confined by the CITZ in the northwest, the Eastern Ghats Mobile Belt in the southeast, and the Mahanadi and Godavari rifts in the northeast and southwest, respectively (Naqvi and Rogers, 1987) (Fig. 1a). Other rock formations bordering the craton include the Mesoproterozoic Pakhal Supergroup, the upper Carboniferous to lower Cretaceous Gondwana Supergroup, and the upper Cretaceous to Eocene Deccan Trap basaltic lava flows (Fig. 1b-c) (Ramachandra,2004).
The Bastar Craton preserves a complex geological history represented by diverse lithological assemblages of different ages, that can be broadly grouped into the following: (a) Paleoarchean tonalite-trondhjemite-granodiorite gneisses (TTG) (Sarkar et al., 1993, Ghosh, 2004, Ramachandra, 2004, Mondal et al., 2019, GSI, 2020); (b) supracrustal rocks of various ages (Mohanty, 2015, Randive et al., 2015, GSI, 2020); (c) granulite terranes (Mishra et al., 1988, Santosh et al., 2004, Vansutre and Hari, 2010, Mukherjee et al., ,2019, Meshram et al., 2021); d) mafic–ultramafic complexes (Dora et al., 2014 and references therein); (e) mafic dyke swarms (Mishra et al., 1988, Mondal et al., 2006, French et al., 2008, GSI, 2020, Srivastava et al., 2021); (f) granites of diverse origin, emplaced at different times (Stein et al., 2004, Panigrahi et al., 2004, Rajesh et al., 2009, Dora et al., 2019, Asokan et al., 2020). The granitic gneisses and undeformed granitoids constitute the basement over which the Precambrian metasedimentary supracrustal sequences were deposited in the riftogenic basins (Crookshank, 1963, Mishra et al., 1988, Ramachandra, 2004).
The Sukma gneissic complex comprising TTGs, potassic granites, metapelites, and calc-silicate gneisses is thought to be the oldest component forming the Paleoarchean basement of the Bastar Craton (ca.3585–3509 Ma) (Sarkar et al., 1993, Ghosh, 2004). These TTG gneisses exhibit polyphase deformation and metamorphism varying from the upper greenschist to granulite facies conditions (Mishra et al., 1988, Ramachandra, 2004, GSI, 2020). The potassic granites associated with these TTGs were also emplaced during the Paleoarchean (Rajesh et al., 2009). Enclaves of gneisses and metasupracrustal rocks occur within younger (Neoarchean) granitoids (Mishra et al., 1988, Ramachandra, 2004, Mondal et al., 2006), which are intrusive into both gneisses and supracrustals (Sarkar et al., 1993). The older supracrustal rocks in Bastar carton (Archaean to Paleoproterozoic), consisting of quartzites, mica schists, phyllites, banded hematite quartzites, and agglomerates, belong to the Sukma, Bengpal, Bailadila, Nandgaon, Dongargarh, Khairagarh, Sausar, Sonakhan, and Sakoli Groups (Mohanty, 2015, Randive et al., 2015, Manu Prasanth et al., 2018, GSI, 2020 and references therein). The Sukma Group overlies the Paleoarchean basement gneisses and constitutes mafic-ultramafics, BIFs, para-amphibolites, and quartzites (Mishra et al., 1988, Mohanty, 2015, GSI, 2020). The Bengpal Group overlies the older Sukma Group with a basal unconformity. The major rock types of the Bengpal Group are quartzites, amphibolites, BIFs, and interlayered metabasalts (Ramachandra, 2004, Mohanty, 2015).
The Paleoarchean/Mesoarchean gneissic complexes and supracrustal sequences are intruded by Neoarchean granitic rocks in the Dongargarh, Kankar, Malanjkhand areas (Stein et al., 2004, Panigrahi et al., 2004, Mohanty, 2015, Asokan et al., 2020) (Fig. 1b-c). The Dongargarh granite intruded along the Kotri belt and is considered the boundary between the eastern and western Bastar Craton (Ramachandra, 2004). More recently, a new tectonic classification scheme has been proposed by Santosh et al. (2020), with the western and the eastern Bastar Cratons separated by an intervening ‘Central Bastar Orogen’ (CBO) (Fig. 1b).
The Archean granitoids and supracrustal sequences of the Bastar Craton are intruded by numerous Proterozoic mafic dyke swarms (ca.2.37–1.42 Ga) of different orientations (French et al., 2008, Srivastava et al., 2021). It has been suggested that the dyke swarms form a bimodal suite, which was derived from subduction-modified metasomatized mantle (Mondal et al. 2006).
Younger supracrustal rocks occur near the southeastern margin of the craton. These comprise several unmetamorphosed Meso to Neoproterozoic sedimentary sequences, including three large sedimentary basins, viz.: (a) the Chhattisgarh basin, (b) the Khariar basin, and (c) the Indravati basin, hosting conglomerates, sandstones, shales, limestones, dolomites and cherts (Naqvi and Rogers, 1987, Patranabis-Deb and Chaudhuri, 2007). The available geochronological data of granitoids from the Bastar Craton is summarized in Table 1.
The present study area (Gondpipri-Dewada) is located in the WBC, about 200 km southeast of Nagpur city in central India (Fig. 1a-b). The WBC comprises Neoarchean TTGs, charnockites, sanukitoids, dismembered mafic–ultramafic rocks, and Proterozoic granites-lamprophyres overlain by cover sediments of Mesoproterozoic to early Cretaceous age. The area represents the northern continuity of the NNW–SSE trending Bhopalpatnam Granulite Belt (BGB), which is a 20–40 km wide and 300 km long belt of granulite facies rocks exposed along the southwestern edge of the craton (Mishra et al., 1988, Mukherjee et al., ,2019, GSI, 2020, Meshram et al., 2021).
The dominant rock types in the region are TTGs and sanukitoids, intruded by ca.1.6 Ga Mul granite (Dora et al., 2019). Intrusions of younger calc-alkaline lamprophyre were also noted within the Mul granite (Meshram et al., 2019, Dora et al., 2021). The field characteristics, sampling details, and sample locations are shown in Fig. 2. A brief description of the field relationships, and samples collected for geochronological and geochemical studies is given below.
The TTGs and sanukitoids are mainly exposed in the Wainganga and Lahan river sections around Ghanpur and Dewada village(Fig. 2). They form discontinuous outcrops in close association with charnockites, metagabbro, and metapyroxenite (Dora, 2012) (Fig. 2, 3a-d). The gneissic banding follows the NNE-SSW to NE-SW regional trend of the WBC rocks (Fig. 3b-c). The tonalitic gneisses and charnockites show gradational contact in the field and share regional-scale intense ductile deformation and metamorphism (Fig. 2). The TTG have a mylonitic foliation in the vicinity of the shear zone passing through the area (Fig. 3b); however, the contact between TTGs and mafic–ultramafic rocks is concealed under thick alluvium (Fig. 2). Isolated patches of TTGs are seen as enclaves within younger granites near Bhejgaon and Bembal. Two varieties of tonalite gneisses were identified, viz., grey gneiss and pink augen gneiss (Fig. 3b-c; Geochronology sample no N-20). In contrast, the K-feldspar-bearing granodioritic gneisses are megacrystic, exposed in the Wainganga river belt near Ghanpur (Fig. 3).
The TTGs are strongly foliated (Fig. 3b-c), showing dark grey tonalite and grey granodiorite bands. They have a stromatic layering (millimeters to few centimeters across) with nebulitic and augen structures and are intensely folded (Fig. 3a). Leucosomes are more common compared to melanosome and mesosome bands. Individual bands show variation in the modal percentage of mafic (biotite ± hornblende) and felsic (plagioclase + quartz + K-feldspar) minerals(Fig. 3a). At places, they host high-grade mafic (two pyroxenes) enclaves (Fig. 3c-d). Sanukitoids also forms discrete bodies closely associated with TTG gneisses in the Lahan river sections near Thanewasna show the effect of deformation (Fig. 2, Fig. 3e).
Granitic intrusions make up a significant component of the continental crust in the Bastar Craton, central India. The granites of the WBC are poorly studied unlike those from Malanjkhand, Dongargarh, Kankar and Paliam-Darba (Panigrahi et al., 2004, Stein et al., 2004, Singh et al., 2017, Dora et al., 2019, Asokan et al., 2020 and reference therein) in other parts of the craton, which have been extensively studied for understanding crustal evolution and metallogenesis.
The Mul granite covers an area of 300 km2 and is exposed mainly around Phutana-Dugara-Bimbal-Nandgaon-Bhejgaon area in the northwestern part of the Thanewasna Cu-Au deposit (Sashidharan, 2007, Mukherjee et al., 2007, Dora et al., 2019, Dora et al., 2021). It is intrusive into the older TTG-charnockite association (Dora et al., 2019) (Fig. 2, Fig. 3f). The granite appears to be homophonous and undeformed (Fig. 3f), comprising quartz, K-feldspar, plagioclase, biotite, hornblende, and rare muscovite.
Based on occurrence and cross-cutting field relationships, three varieties of Mul granite are recognized: (1) medium-grained grey granite, (2) fine-grained equigranular pink granite, (3) pegmatoidal granite. The granites are generally massive but display crude N-S to NNW-SSE trending easterly dipping foliation near the contact zone with TTGs and sanukitoids. Near Bimbal and Dewada area, enclaves of metagabbros and TTGs are profusely seen within granites. The grey granite type is widespread and forms batholithic bodies, whereas the pink type forms small-scale bodies of limited areal extent in the vicinity of the Thanewasna shear zone. The pink color of granite is likely caused by hydrothermal alteration (Dora, 2012). The presence of magmatic fabric, absence of deformation-induced planar fabric, and unaltered mineralogy suggest late- to post-tectonic emplacement synchronous with Cu-Au mineralization in the WBC (Dora et al., 2019, Dora et al., 2020).
Section snippets
Sampling
The study area was mapped on a 1:12,500 scale, and representative bedrock samples, each weighing ~ 5 kg, were collected from fresh outcrops of TTGs (n = 5), sanukitoids(n = 6), and Mul granites (n = 30). Representative thin sections were studied under a polarizing petrographic microscope, and the least altered samples (n = 41) were selected for geochemical studies. The rocks were crushed and pulverized into a fine powder (-200 mesh sieve) for geochemical analyses. The sample locations are
1. Petrographic relations
The variations in the plagioclase/alkali feldspar ratio and modal percentage of ferromagnesian minerals was used to group the granitoids into three groups: TTGs, sanukitoids, and granites. A detailed description of each rock type is provided below.
Petrogenesis of TTGs and sanukitoids
4.1.1. TTGs: The TTGs from the WBC have low (Na2O + K2O)/(FeOt + MgO + TiO2) and Al2O3/(FeOt + MgO + TiO2) ratios and mostly plot in the field of melts derived from amphibolite and metabasalt–meta tonalite (Patiño Douce, 1999). Based on the REE concentrations, they can be differentiated into low and high HREE groups, the difference being attributed primarily to different depths of melting (Halla et al., 2009, Moyen, 2011). However, in the source discrimination diagram for Archean granitoid by
Concluding remarks
This study integrates field, petrographic, bulk-rock geochemistry, U-Pb zircon and EMP monazite geochronology of Neoarchean TTGs, sanukitoids, and Paleoproterozoic Mul granite combined with Sm-Nd isotope data from mafic enclaves in TTG from the WBC in central India. The integrated study is used to elucidate crustal evolution and geodynamics between ca. 2544 and 790 Ma along the western margin of the Bastar Craton on the northern shoulder of the PG valley. The main conclusions from this study
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
MLD extends sincere thanks to Dr. Ranjit Rath, Director General, not only for his encouragement but also for continuous inspiration and thoughtful discussion. Authors extend sincere thanks to Shri G. Vidyasagar, Addl. Director-General and HoD, Geological Survey of India, Nagpur, for granting permission to publish this paper. MLD, thank Shri. Sanjeev Raghav, Dy Director General, and RMH-III for his continuous encouragement to write this manuscript and Dr. Manash Roy Choudhry, Director, and
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Rift-induced structurally controlled hydrothermal barite veins in 1.6 Ga granite, Western Bastar Craton, Central India: Constraints from fluid inclusions, REE geochemistry, sulfur and strontium isotopes studies
2022, Ore Geology ReviewsCitation Excerpt :The craton is essentially composed of ca. 3.60–3.51 Ga Tonalite-Trondhjemite-Granodiorite (TTG) suites, granites, amphibolite, and Proterozoic supracrustals with 2.5 Ga granite gneisses and mafic dykes (Sarkar et al., 1993; Ghosh, 2004; Ramachandra 2004; Rajesh et al., 2009; Santosh et al., 2020; Srivastava et al., 2021). The older gneiss-supracrustal assemblages are intruded by 1.6 Ga granitoid plutons of varying dimensions and are traversed by numerous quartz-chlorite-barite veins (Ramachandra 2004; Dora and Randive, 2015; Dora et al., 2020, 2021; Fig. 2a–c). The NW-SE trending and 450 km long Proterozoic PG rift basin occur at the tectonic juncture of the Dharwar and the Bastar cratons (Fig. 1b) (Santosh et al., 2004; Meshram et al., 2021).
Neoarchean–Paleoproterozoic HP-HT metamorphism in the Bhopalpatnam granulite belt, Bastar Craton (India): Insights from phase equilibria modelling and monazite geochronology
2022, Precambrian ResearchCitation Excerpt :The psammo-pelitic gneiss (sample 18–46) from the BGB preserves a dominant age population at 1425–1345 Ma (1388 ± 24 Ma; MSWD = 0.50; n = 10), with a younger population at 1170–1102 Ma (1126 ± 55 Ma; MSWD = 0.35; n = 2). These ages are comparable with U–Pb zircon ages obtained for Mul granite (∼1.36 Ga and ∼ 1.14 Ga; Dora et al., 2021), which is emplaced in the northwestern BGB. Therefore, we speculate that the psammo-pelitic gneisses are interpreted to record a strong thermal imprint associated with the emplacement of Mul granite in the BGB.