Structural pattern in the Precambrian rocks of Sonua-Lotapahar region, north Singhbhum, eastern India

Mukhopadhyay, Dhruba ; Bhattacharya, Tapas ; Chakraborty, Tapan ; Dey, Arun Kanti (1990) Structural pattern in the Precambrian rocks of Sonua-Lotapahar region, north Singhbhum, eastern India Proceedings of the Indian Academy of Sciences - Earth and Planetary Sciences, 99 (2). pp. 249-268. ISSN 0253-4126

PDF - Publisher Version

Official URL:

Related URL:


In the western part of the North Singhbhum fold belt near Lotapahar and Sonua the remobilized basement block of Chakradharpur Gneiss is overlain by a metasedimentary assemblage consisting of quartz arenite, conglomerate, slate-phyllite, greywacke with volcanogenic material, volcaniclastic rocks and chert. The rock assemblage suggests an association of volcanism, turbidite deposition and debris flow in the basin. The grade of metamorphism is very low, the common metamorphic minerals being muscovite, chlorite, biotite and stilpnomelane. Three phases of deformation have affected the rocks. The principal D1 structure is a penetrative planar fabric, parallel to or at low angle to bedding. No D1 major fold is observed and the regional importance of this deformation is uncertain. The D2 deformation has given rise to a number of northerly plunging major folds on E-W axial planes. These have nearly reclined geometry and the L2 lineation is mostly downdip on the S2 surface, though some variation in pitch is observed. The morphology of D2 planar fabric varies from slaty cleavage/schistosity to crenulation cleavage and solution cleavage. D3 deformation is weak and has given rise to puckers and broad warps on schistosity and bedding. The D2 major folds south of Lotapahar are second order folds in the core of the Ongarbira syncline whose easterly closure is exposed east of the mapped area. Photogeological study suggests that the easterly and westerly closing folds together form a large synclinal sheath fold. There is a continuity of structures from north to south and no mylonite belt is present, though there is attenuation and disruption along the fold limbs. Therefore, the Singhbhum shear zone cannot be extended westwards in the present area. There is no evidence that in this area a discontinuity surface separates two orogenic belts of Archaean and Proterozoic age.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:North Singhbhum; Singhbhum Shear Zone; Structural Geometry; Polyphase Deformation; Volcaniclastic Rocks; Lithological Characteristics; Deformation History
ID Code:21610
Deposited On:22 Nov 2010 11:12
Last Modified:17 May 2016 05:48

Repository Staff Only: item control page