Abstract:In the Precambrian Singhbhum stratigraphy, some enigmatic aspects exist as regards to Dangoaposi and Jagannathpur lavas. The existing enigma embodies locational aspects of these lavas, structural characteristics, stratigraphic position, and geochemical affinities. Based on recent field studies by the authors and knowledge acquired from existing literature, a possible solution has been proposed in the present study, which may be followed by Precambrian geologists in order to avoid all existing confusion and dil… Show more
“…For the Singhbhum Craton of Peninsular India, the following important points are to be noted: (i) the Singhbhum Craton covers an area of ∼39 000 km 2 and forms a N–S elongate ovoid block lying between 84.5 °E to 86.5 °E and 21 °N to 22.75 °N in eastern India. This craton also embraces different rock units ranging in age from 3.5 to 2.5 Ga (Mukhopadhyay, 2001; Matin et al 2012; Sarkar & Gupta, 2012; Mukhopadhyay & Matin, 2020); (ii) The North Singhbhum Mobile Belt is thrust over the Singhbhum Craton along the arcuate Singhbhum Shear Zone, where the Singhbhum Shear Zone has a history of reactivation multiple times; (iii) The stratigraphic succession of the Singhbhum–Orissa Craton has been reported by Saha et al (1988) and Misra (2006) (Table 1); (iv) This stratigraphic succession has scope for further modification considering the availability of geochronological data (Mukhopadhyay & Matin, 2020 and recent studies by other workers; see Table 1); (v) The Iron Ore Group (IOG) basin as a whole comprises three principal sub-parts which are: the western IOG belt (Noamundi–Jamda–Koira basin), eastern IOG belt (Gorumahisani–Badampahar basin) and southern IOG belt (Tomka–Daitari basin) (Fig. 1); (vi) Some important geochronological data for the western IOG include an age of 3392 ± 29 Ma (Basu et al 2008).…”
Section: Geological Backgroundmentioning
confidence: 91%
“… Fig. 1. Regional map showing disposition of several rock units in the Singhbhum North Orissa region, eastern India (after Saha, 1994; Misra, 2006; Singh et al 2016); marked areas represent investigated sectors: a – Koira sector, b – Gua–Manoharpur sector and c – Sahedba–Santara sector. Inset map shows distribution of different cratons in the Peninsular India (Sharma, 2009); DhC – Dharwar Craton; BaC – Bastar Craton; SiC – Singhbhum Craton; BuC – Bundelkhand Craton; ArC – Aravalli Craton.…”
The petrogenesis of Palaeoarchaean mafic–ultramafic rock suites from the western Iron Ore Group, Singhbhum Craton, eastern India, has been evaluated based on the chemistry of constituent mineral phases. The rock suites include basaltic rocks and mafic (gabbro) to ultramafic (serpentinized peridotite) intrusive rocks, which occur in host rocks covering phyllite, ferruginous shale, banded haematite quartzite and jasper. The constituent clinopyroxene shows dominant uralitization, whereas plagioclase grains are generally saussuritized, being marked by relatively tiny granular aggregates of albite, chlorite, epidote and K-feldspar. The ultramafic intrusive rocks are overwhelmingly serpentinized. Clinopyroxene compositions are augitic, whereas relict plagioclase is typically bytownite. Amphiboles of the investigated rock suites are divisible into the ‘uralite’ type (occurring peripherally to clinopyroxene) and the ‘completely changed-over amphibole’ type (with no traces of initial clinopyroxene). Both the amphibole types belong to the ‘calcic group’, showing a compositional spectrum from actinolite–magnesiohornblende–ferrohornblende–ferroactinolite. Opaque minerals include magnetite (both Cr-magnetite and Al-magnetite), chromite (Al-chromite) and ilmenite, whereas serpentine (belonging to the ultramafic intrusive rocks) corresponds to lizardite. Looking at the mineral compositions of the pyroxene, glass and amphibole, the studied rock suites show a wide equilibration temperature–pressure domain range (∼750 °C to ∼1400 °C at ∼0.26 kbar to ∼21 kbar), which corresponds to an ascending magma that underwent a ‘hydration event’ at a shallow level. The assessment of the clinopyroxene and spinel chemistry characteristically suggests an arc setting for the parent magma that has undergone both equilibrium and fractional crystallization in the course of magmatic evolution. During differentiation, the magmatic density remains almost constant, with variable oxygen fugacity.
“…For the Singhbhum Craton of Peninsular India, the following important points are to be noted: (i) the Singhbhum Craton covers an area of ∼39 000 km 2 and forms a N–S elongate ovoid block lying between 84.5 °E to 86.5 °E and 21 °N to 22.75 °N in eastern India. This craton also embraces different rock units ranging in age from 3.5 to 2.5 Ga (Mukhopadhyay, 2001; Matin et al 2012; Sarkar & Gupta, 2012; Mukhopadhyay & Matin, 2020); (ii) The North Singhbhum Mobile Belt is thrust over the Singhbhum Craton along the arcuate Singhbhum Shear Zone, where the Singhbhum Shear Zone has a history of reactivation multiple times; (iii) The stratigraphic succession of the Singhbhum–Orissa Craton has been reported by Saha et al (1988) and Misra (2006) (Table 1); (iv) This stratigraphic succession has scope for further modification considering the availability of geochronological data (Mukhopadhyay & Matin, 2020 and recent studies by other workers; see Table 1); (v) The Iron Ore Group (IOG) basin as a whole comprises three principal sub-parts which are: the western IOG belt (Noamundi–Jamda–Koira basin), eastern IOG belt (Gorumahisani–Badampahar basin) and southern IOG belt (Tomka–Daitari basin) (Fig. 1); (vi) Some important geochronological data for the western IOG include an age of 3392 ± 29 Ma (Basu et al 2008).…”
Section: Geological Backgroundmentioning
confidence: 91%
“… Fig. 1. Regional map showing disposition of several rock units in the Singhbhum North Orissa region, eastern India (after Saha, 1994; Misra, 2006; Singh et al 2016); marked areas represent investigated sectors: a – Koira sector, b – Gua–Manoharpur sector and c – Sahedba–Santara sector. Inset map shows distribution of different cratons in the Peninsular India (Sharma, 2009); DhC – Dharwar Craton; BaC – Bastar Craton; SiC – Singhbhum Craton; BuC – Bundelkhand Craton; ArC – Aravalli Craton.…”
The petrogenesis of Palaeoarchaean mafic–ultramafic rock suites from the western Iron Ore Group, Singhbhum Craton, eastern India, has been evaluated based on the chemistry of constituent mineral phases. The rock suites include basaltic rocks and mafic (gabbro) to ultramafic (serpentinized peridotite) intrusive rocks, which occur in host rocks covering phyllite, ferruginous shale, banded haematite quartzite and jasper. The constituent clinopyroxene shows dominant uralitization, whereas plagioclase grains are generally saussuritized, being marked by relatively tiny granular aggregates of albite, chlorite, epidote and K-feldspar. The ultramafic intrusive rocks are overwhelmingly serpentinized. Clinopyroxene compositions are augitic, whereas relict plagioclase is typically bytownite. Amphiboles of the investigated rock suites are divisible into the ‘uralite’ type (occurring peripherally to clinopyroxene) and the ‘completely changed-over amphibole’ type (with no traces of initial clinopyroxene). Both the amphibole types belong to the ‘calcic group’, showing a compositional spectrum from actinolite–magnesiohornblende–ferrohornblende–ferroactinolite. Opaque minerals include magnetite (both Cr-magnetite and Al-magnetite), chromite (Al-chromite) and ilmenite, whereas serpentine (belonging to the ultramafic intrusive rocks) corresponds to lizardite. Looking at the mineral compositions of the pyroxene, glass and amphibole, the studied rock suites show a wide equilibration temperature–pressure domain range (∼750 °C to ∼1400 °C at ∼0.26 kbar to ∼21 kbar), which corresponds to an ascending magma that underwent a ‘hydration event’ at a shallow level. The assessment of the clinopyroxene and spinel chemistry characteristically suggests an arc setting for the parent magma that has undergone both equilibrium and fractional crystallization in the course of magmatic evolution. During differentiation, the magmatic density remains almost constant, with variable oxygen fugacity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
