A review of the inferred geodynamic evolution of the Dharwar craton over the ca. 3.5–2.5 Ga period, and possible implications for global tectonics

Abstract

Abstract:The geological history and evolution of the Dharwar craton from ca. 3.5-2.5 Ga is reviewed and briefly compared with a second craton, Kaapvaal, to allow some speculation on the nature of global tectonic regimes in this period. The Dharwar craton is divided into western (WDC) and eastern (EDC) parts (separated possibly by the Closepet Granite Batholith), based on lithologi-cal differences and inferred metamorphic and magmatic genetic events. A tentative evolution of the WDC encompasses an early, ca. 3.5 Ga protocrust possibly forming the basement to the ca. 3.35-3.2 Ga Sargur Group greenstone belts. The latter are interpreted as having formed through accretion of plume-related ocean plateaux. The approximately coeval Peninsular Gneiss Complex (PGC) was possibly sourced from beneath plateau remnants, and resulted in high-grade metamorphism of Sargur Group belts at ca. 3.13-2.96 Ga. At about 2.9-2.6 Ga, the Dharwar Supergroup formed, comprising lower Bababudan (largely braided fluvial and subaerial volcanic deposits) and upper Chitradurga (marine mixed clastic and chemical sedimentary rocks and subaqueous volcanics) groups. This supergroup is preserved in younger greenstone belts with two distinct magmatic events, at 2.7-2.6 and 2.58-2.54 Ga, the latter approximately coincident with ca. 2.6-2.5 Ga granitic magmatism which essentially completed cratonization in the WDC. The EDC comprises 2.7-2.55 Ga tonalite-trondhjemitegranodiorite (TTG) gneisses and migmatites, approximately coeval greenstone belts (dominated by volcanic lithologies), with minor inferred remnants of ca. 3.38-3.0 Ga crust, and voluminous 2.56-2.5 Ga granitoid intrusions (including the Closepet Batholith). An east-to-west accretion of EDC island arcs (or of an assembled arc -granitic terrane) onto the WDC is debated, with a postulate that the Closepet Granite accreted earlier onto the WDC as part of a "central Dharwar" terrane. A final voluminous granitic cratonization event is envisaged to have affected the entire, assembled Dharwar craton at ca. 2.5 Ga. When Dharwar evolution is compared with that of Kaapvaal, while possibly global magmatic events and freeboard-eustatic changes at ca. 2.7-2.5 Ga may be identified on both, the much earlier cratonization (by ca. 3.1 Ga) of Kaapvaal contrasts strongly with the ca. 2.5 Ga stabilization of Dharwar. From comparing only two cratons, it appears that genetic and chronologic relationships between mantle thermal and plate tectonic processes were complex on the Archaean Earth. The sizes of the Kaapvaal and Dharwar cratons might have been too limited yet to support effective thermal blanketing and thus accommodate Wilson Cycle onset. However, tectonically driven accretion and amalgamation appear to have predominated on both evolving cratons.Résumé : L'histoire géologique et l'évolution du craton de Dharwar (ϳ3,5-2,5 Ga) sont examinées et sommairement comparées a` celles d'un second craton, celui de Kaapvaal, afin de permettre une certaine spéculation sur la nature des régimes tectoniques globaux duran...

Depositional environment of polymictic conglomerate of the Gadag greenstone Belt, Western Dharwar Craton, south India: An insight for Neoarchean marginal sedimentation

“…The Dharwar Craton based on geological evolution, magmatic events, structure, age, and thickness of the crust is divided into the Western and Eastern Dharwar Craton (EDC) (Chardon & Jayananda, 2008; Gupta et al, 2003; Naqvi et al, 1983; Naqvi & Rogers, 1987; Sunder Raju, Eriksson, Catuneanu, Sarkar, & Banerjee, 2014; Swami Nath, Ramakrishnan, & Viswanatha, 1976). Recent petrological, isotopic, and geochronologic studies from the Dharwar cratonic Block indicated three distinct age provinces (Western [WDC], Central [CDC], and Eastern [EDC]) separated by NW‐SE shear zones (Figure 1a; Jayananda et al, 2013, 2019; Jayananda, Chardon, Peucat, Tushipokla, & Fanning, 2015; Peucat et al, 2013).…”

Evolution of a Mesoarchean suprasubduction zone mantle wedge in the Dharwar Craton, southern India: Evidence from petrology, geochemistry, zircon U–Pb geochronology, and Lu–Hf isotopes

“…Charnockites in the southern part of the EDC are also dated at 2.51 Ga (Figure 1) and correlated with the timing of assembly between the EDC and WDC (Li, Santosh, & Palin, 2018). The CDC preserves >3-Ga TTG gneiss arc basement (the Sargur Group) and 2.52-to 2.50-Ga calc-alkaline magmas of the N-S-oriented Closepet granite batholith (Chardon et al, 2011;Jayananda et al, 2013;Raju et al, 2014). Jayananda et al (2013) suggested that the metamorphic events occurred at 2.44 Ga in the western and southern regions of the CDC.…”

“…The EDC is younger than the WDC and is composed of 2.80-to 2.70-and 2.55-to 2.53-Ga TTG gneisses in its core (Raju, Eriksson, Catuneanu, Sarkar, & Banerjee, 2014). Charnockites in the southern part of the EDC are also dated at 2.51 Ga (Figure 1) and correlated with the timing of assembly between the EDC and WDC (Li, Santosh, & Palin, 2018).…”

Petrological Characteristics of the Peddavura Schist Belt and Adjacent Rocks in Eastern Dharwar Craton in Parts of Nalgonda District, Telangana State

“…The EDC is characterized by voluminous late Archaean Granitoids of 2.51 -2.75 Ga, with minor gneisses TTG-Tonalite-TrondhjemiteGranodiorite and Migmatites, dominated by thin Volcanic Lithologies schist belt along Dharwar age. It seems that Chronologic and the Genetic bonds between plate tectonics and mantle thermal processes were Archaean Earth complex stages, while the Schist Belt Craton is metamorphosed of Greenschist to Amphibolites Facies regional metamorphism [1]. There is an extraordinary metal concentrated Mineral deposit forming Magmatic, and Magmatic-Hydrothermal Geodynamic environmental processes typically of high thermal and mechanical energy close to plate boundaries.…”