U-Pb dating of metamorphic monazite establishes a Pan-African age for tectonism in the Nallamalai Fold Belt, India

Sheppard, S. and Rasmussen, B. and Zi, J. and Soma Sekhar, V. and Srinivasa Sarma, D. and Ram Mohan, M. and Krapež, B. et al. 2017. U-Pb dating of metamorphic monazite establishes a Pan-African age for tectonism in the Nallamalai Fold Belt, India. Journal of the Geological Society. 174 (6): pp. 1062-1069.

Source Title

Journal of the Geological Society

DOI

10.1144/jgs2017-051

ISSN

0016-7649

School

John de Laeter Centre

URI

http://hdl.handle.net/20.500.11937/58974

Collection

Curtin Research Publications

Abstract

© 2017 The Author(s). The Nallamalai Fold Belt comprises late Palaeoproterozoic to Mesoproterozoic sedimentary rocks deformed into a fold-and-thrust belt along the eastern side of Peninsular India. The age of thin-skinned thrusting, folding and low- to mediumgrade metamorphism in the belt is unclear, with estimates ranging from Palaeoproterozoic to early Palaeozoic. A possible Pan- African age for thrusting has previously been inferred from Rb-Sr dating of muscovite in shear zones from the adjacent Krishna Province (501 - 474 Ma) but these structures are separated from the Nallamalai Fold Belt by a major thrust. Here, we present in situ U-Pb dating of metamorphic monazite within a low-grade metasedimentary rock in the Nallamalai Fold Belt at the Mangampeta barite mine. Our date of 531 ± 7 Ma for the monazite is the first direct evidence that west- to NW-directed nappe stacking, folding and low-grade metamorphism in the fold belt are related to Pan-African incorporation of India into the Gondwana supercontinent.