On the Occurrence of Two Intersecting Pre-Cambrian Orogenic Belts in Singhbhum and Adjacent Areas, India

Sarkar, Sounak; Saha, Ashis Kumar

doi:10.1017/s0016756800055060

Cited by 37 publications

(6 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The type area of the IOG (c.3,100 Ma; Saha et al, 1988) lies in the Noamundi‐Jamda‐Koira valley in the southern part of western IOG basin (trending NNE–SSW). Earlier workers suggested a synclinorium structure for the western IOG which was confirmed subsequently on the basis of tectonic analysis endorsing to a regional structure of synclinorium overturned towards the southeast (Jones, 1934; Sarkar & Saha, 1962, 1963). Mukhopadhyay et al (2008) documented 3,506.8 ± 2.3 Ma U–Pb SHRIMP Zircon age for dacitic lava from the southern IOG.…”

Section: Geological Settingmentioning

confidence: 78%

Mafic volcanic rocks of western Iron Ore Group, Singhbhum Craton, eastern India: Geochemical evidence for ocean–continent convergence

et al. 2020

View full text Add to dashboard Cite

Precambrian mafic magmatism is an important global episode which played a significant role in the crustal evolution. In India, Singhbhum Craton being the oldest craton, witnessed significant occurrences of Precambrian geological activity, marked by several episodes of volcanism, plutonism, sedimentation spanning from Palaeoarchean to Mesoproterozoic age. Here we present petrological and geochemical characteristics of Precambrian mafic volcanic rocks (occurring in western Iron Ore Group (IOG), Singhbhum Craton, eastern India) to evaluate their petrogenetic aspects, tectonic setting, and magma generation. The mafic volcanic rocks are porphyritic in nature with the phenocrysts of plagioclase and groundmass composed of clinopyroxene, plagioclase, ilmenite, and volcanic glass. These rocks are mostly tholeiitic, sometimes with a transitional behaviour towards calc‐alkaline nature and display basalt‐basaltic andesite affinity. These mafic volcanic rocks also preserve geochemical signatures (high Nb/U, Nb/La, [Nb/Th]pm ratios) in support of Nb‐enriched basalts and are classified as Nb‐enriched basalts (NEB; Nb > 7 ppm) and high‐Nb basalts (HNB; Nb > 20 ppm) on the basis of Nb concentrations and mantle normalized Nb/La ratios (>0.5). The NEBs and HNBs are marked by lesser magnitude of negative Nb anomalies with high (Nb/Th)pm, (Nb/La)pm, and Nb/U ratios as compared to normal arc basalts. Several major element oxides, trace elements, and selected element ratios (like SiO2, CaO/Al2O3, Y, V/Cr, Zr/Nb, and ∑REE) show systematic variations with MgO which suggests role of magmatic fractionation. Chondrite‐normalized REE patterns for NEB and HNB rocks exhibit uniform LREE enrichment with distinct Eu negative anomalies while primitive mantle‐normalized incompatible trace element patterns reflect enrichment in LILE and LREE with prominent Nb‐Ta anomalies. Different HFSE ratios corroborate a subduction related setting for magma generation formed by ∼10%–20% melting in the domain of garnet lherzolite. Relative enrichment of LILE and LREE with depleted HFSE characteristics attest a garnet‐bearing mantle source and melt extraction with garnet in the residue. Geochemical signatures suggest that the genesis of NEB and HNB is attributable to slab‐melting and wedge hybridization processes during matured stages of subduction. Selected incompatible trace element ratios for the studied mafic volcanic rocks invoke an enriched (EM1‐EM2 type) mantle source and unequivocally suggest effects of continental crustal assimilation of the parent magma. Liquid immiscibility has played an important role as a differentiation mechanism leading to presence of high and low FeO types. The IOG mafic volcanic rocks preserve distinct geochemical signatures of matured stage of subduction, slab melting, crustal contamination and magma generation at an Archean ocean–continent convergent margin setting.

show abstract

Section: Geological Settingmentioning

confidence: 78%

Mafic volcanic rocks of western Iron Ore Group, Singhbhum Craton, eastern India: Geochemical evidence for ocean–continent convergence

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The SSZ occurs close to the stratigraphic boundary between the Dhanjori Group and the Chaibasa Formation of the Singhbhum Group. The SSZ is interpreted to represent a deep-seated, crustal-scale, N-dipping tectonic dislocation zone (Sarkar & Saha, 1962; Banerji, 1969, 1981), which localized penetrative shear deformation during top-to-south thrust movement of the NSMB block onto the southern Archaean Singhbhum Craton (Ghosh & Sengupta, 1987; Sengupta & Ghosh, 1997; Mukhopadhyay & Matin, 2020; Roy & Matin, 2020). Based on structural observations, such as a continuous increase in the deformation intensity, increasing fold tightness and continuity of mineral lineation from the NSMB to the SSZ, Ghosh & Sengupta (1987) suggested that the progressive deformation in the mobile belt and in the SSZ was synchronous.…”

Section: Geological Settingmentioning

confidence: 99%

Timing of shear deformation in the Singhbhum Shear Zone, India: implications for shear zone-hosted polymetallic mineralization

Pal

Selby²,

Sarangi³

2022

Geol. Mag.

View full text Add to dashboard Cite

The Singhbhum Shear Zone in eastern India hosts several Fe oxide–Cu–Au (IOCG)-type polymetallic deposits, mined primarily for U, Cu and apatite, with elevated concentrations of rare earth elements, Ni, Co, Mo, Te and Au in association with low-Ti magnetite. Although the main stages of hydrothermal U, Cu and rare earth element mineralization are known to be Palaeoproterozoic in age, the age of shear deformation in the host shear zone has hitherto not been constrained. Here, we report Re–Os ages of syn-shearing massive molybdenite occurring along shear surfaces transecting the uranium ores in the Jaduguda uranium deposit. Integrating the obtained Re–Os age of c. 1.64–1.59 Ga of molybdenite, the known ages of mineralization and the known tectonothermal events in the adjoining Proterozoic Mobile Belt, we propose that the main stages of polymetallic hydrothermal mineralization pre-dated the pervasive shear deformation event in the Singhbhum Shear Zone. We further suggest that the shear zone was not the principal foci of the hydrothermal mineralization of the main stages. Instead, the shear zone was localized during the Palaeoproterozoic to Mesoproterozoic transition (c. 1.64–1.59 Ga) along pre-existing crustal-scale extensional faults which had earlier been the foci of hydrothermal alteration and mineralization in Palaeoproterozoic time (c. 1.9–1.8 Ga). Shear deformation and metamorphism have reconstituted/redistributed existing mineral/metal inventories with/without neo-mineralization.

show abstract

“…According to the pioneer workers, the Kuliana gabbro‐anorthosite rocks are coeval with the rocks of the basic volcanics‐dominated Iron Ore Group, and thus older than the Singhbhum Granite (Dunn and Dey, ). On the basis of field relations from some other locations in the eastern Indian shield, Sarkar and Saha (, ) interpreted a younger age of this suite relative to the Singhbhum Granite. Furthermore, in contrast to the view of comagmatic evolution of these gabbro‐anorthosite rocks and the Mayurbhanj Granite, as inferred by Iyenger and Alwar (), a relatively older age of the former has been suggested (Saha et al ., ).…”

Section: Geological Settingmentioning

confidence: 99%

Crystal size distribution analysis of plagioclase from gabbro‐anorthosite suite of Kuliana, Orissa, eastern India: implications for textural coarsening in a static magma chamber

2015

View full text Add to dashboard Cite

The layered gabbro-anorthosite suite in the eastern Indian shield is ideal for a texture based study of the crystallization history of a mafic magma in a static magma chamber. The magmatic suite comprises 40-150 m thick persistent layers of different lithounits, which have been divided into two cycles. The lower cycle (I) is represented from bottom to top by gabbro, gabbronorite, leucogabbronorite, anorthositic gabbronorite and anorthositic gabbro. The upper cycle (II) is similar to cycle I, except that the anorthositic gabbronorite and anorthositic gabbro units are not present there. The characteristic textures of different lithounits in each cycle repeats with repetition in lithology. Distinctive textures observed in the suite have been classified into three categories, Types I, II and III. Adcumulus growth was the principle crystallization mechanism for Types I and III textures, which are characteristically present in the lower layers of cycle I and cycle II. The upper layers of cycle I show Type II texture, typically with bimodal size distribution of plagioclase, and pyroxene oikocrysts. Thus, Type II texture indicates a possible interplay between adcumulus growth and either polybaric crystallization or textural coarsening processes. Electron microprobe analysis (EPMA) data indicate uniform composition of plagioclase (An 76-85 ), both from inclusions in pyroxene oikocrysts and from groundmass grains, hence ruling out the possibility of involvement of the polybaric crystallization in the layers with Type II texture. Crystal size distribution (CSD) analysis of plagioclase grains stands for textural coarsening process, and the graphical plots have been utilized to quantify the process. P-T calculation using EPMA data from selected pyroxene grains suggests that the textural coarsening took place at about 13.3 kb pressure and 990°C temperature. We propose that adcumulus growth operating in a static magma chamber for a long period of time might have created conditions conducive for textural coarsening process to take place.

show abstract

On the Occurrence of Two Intersecting Pre-Cambrian Orogenic Belts in Singhbhum and Adjacent Areas, India

Cited by 37 publications

References 2 publications

Mafic volcanic rocks of western Iron Ore Group, Singhbhum Craton, eastern India: Geochemical evidence for ocean–continent convergence

Mafic volcanic rocks of western Iron Ore Group, Singhbhum Craton, eastern India: Geochemical evidence for ocean–continent convergence

Timing of shear deformation in the Singhbhum Shear Zone, India: implications for shear zone-hosted polymetallic mineralization

Crystal size distribution analysis of plagioclase from gabbro‐anorthosite suite of Kuliana, Orissa, eastern India: implications for textural coarsening in a static magma chamber

Contact Info

Product

Resources

About