1420 Ma diabasic intrusives from the Mesoproterozoic Singhora Group, Chhattisgarh Supergroup, India: Implications towards non-plume intrusive activity

Abstract

Besides offering significant clues towards tracking the geochemical evolution of the mantle and architectural reconstruction of different 'supercontinent', geochronological and geochemical appraisal of igneous inputs are also important to bracket the depositional time frame of any lithopackage, particularly, the unfossiliferous sedimentary successions. The present study deals with diabasic intrusive within Mesoproterozoic Saraipalli Formation, which is an argillaceous constituent present at the basal part of nearly 400 m thick four-tiered unmetamorphosed but deformed sedimentary succession of Singhora Group, Chhattisgarh Supergroup, central India. The SE-NW trending intrusive comprises mainly of plagioclase and augite together with minor orthopyroxene, biotite and opaque minerals. Though some plagioclase laths are partially sericitized, the ophitic-to-subophitic texture of the rock is well preserved. Major and trace element geochemical data indicate that this intrusive is basalt-to-basaltic andesite in character and of subalkaline basalt affinity. Multi-element plot shows overall LILE-enrichment and enrichment of Pb and slight depletion of Nb and P, coupled with moderate La/Nb and Th/Nb ratios. Zr, Y and Nb ternary diagrams plot in the fields of within plate basalt. Selected HFSE ratios indicate a non-plume source with crustal assimilation/sediment mixing. Sm-Nd and Rb-Sr isotope data show that the intrusive has Sr initial and Nd initial of 0.709377-0.706672 and 0.510919-0.510815, respectively. Positive ε t Nd [t = 1420 Ma] values (+0.3 to + 2.3) indicate depleted isotopic nature of their protolith. The calculated T DM age is 1.7-1.9 Ga. The mineral-whole rock isochron data (Sm-Nd systematics) of the intrusive implies an emplacement age of ca. 1420 Ma. Considering synchronous terrain boundary shear zone development in Bastar craton on the southeastern part of the Singhora basin, mafic magmatism in Eastern Ghats and large-scale basic intrusion in Sausar mobile belt, a major tectono-thermal event around 1400 Ma is surmised that affected eastern Indian craton. Moreover, geochronology of a bedded porcellanite unit (ca. 1500 Ma) at the base and a discordant basic intrusive (ca. 1420 Ma) allowed a unique opportunity to qualitatively offer an upper bound of time bracket for the deposition of Saraipalli Formation, i.e., ∼80 Ma.

Mesoproterozoic 40 Ar– 39 Ar ages of some lamproites from the Cuddapah Basin and Eastern Dharwar Craton, southern India: implications for diamond provenance of the Banganapalle Conglomerates, age of the Kurnool Group and Columbia tectonics

“…43 Ga ages of the Garledinne, Ramadugu (R-4) and Pochampalle lamproites from our study broadly overlap with the 1421 ± 21 Ma (Sm-Nd mineral, whole-rock isochron) age of the diabase intrusion recorded in the basal Singhora Group in the Chhattisgarh Basin, Bastar Craton(Das et al 2011). The lamproite ages also overlap with the: (i) 1455 ± 80 Ma and 1464 ± 63 Ma ages of the felsic and mafic magmatic rocks reported from the EGMB(Shaw et al 1997) ; (ii) 1424 ± 57 Ma and 1357 ± 45 Ma (Rb-Sr whole-rock) crystallization ages reported for basement alkaline rocks from the Draksharama-A and Endamuru-A highs respectively of the oil-and natural gas-bearing Jurassic pericratonic Krishna-Godavari basin, southern India(Gupta et al 2020) ; and (iii) 1460-1450 Ma Lakhna mafic dykes located in the easternmost part of the Bastar Craton(Ratre et al 2010; Pisarevsky et al 2013).…”

“…Our data suggest that a major tectono-thermal event at about 1400 Ma overprinted the easternmost parts of the Indian Shield, including the crustal granulites, the Eastern Dharwar and Bastar Cratons as well as their sedimentary basins, respectively (e.g. Cuddapah, Chhattisgarh and Khariar; cf Das et al 2011)…”

High authigenic Co enrichment in the non‐euxinic buff‐grey and black shale of the Chandarpur Group, Chhattisgarh Supergroup: Implication for the late Mesoproterozoic shallow marine redox condition

“…The U-Pb dating of porcellanites and diabasic intrusive rocks in the underlying Singhora Group, ~100 m above the base of the basin, has consistently yielded an age ~1.4 Ga (Bickford, Basu, Mukherjee, Hietpas, et al, 2011;Bickford et al, 2011aBickford et al, , 2011bDas et al, 2011) and another tuff unit 2,200 m above the base (near the top of the basin), and part of the Raipur Group has yielded an age ~1.0 Ga (Patranabis-Deb et al, 2007). The palaeontological study of the Chaporadih and Chandarpur formations has recovered organic-walled microfossils unique to the late Mesoproterozoic-early Neoproterozoic age (Singh & Sharma, 2016).…”

Ediacaran macroalgal holdfasts and their evolution: a case study from China

“…1420 Ma by Das et al . ) of the Singhora Group (Babu & Singh ; Sharma & Singh ), and Eopalmaria has also been recorded from the Nagod Limestone and Sirbu Shale formations of the Neoproterozoic Bhander Group (Singh et al . ).…”