Late Archean manganese mineralization and younger supergene manganese ores in the Anmod–Bisgod region, Western Dharwar Craton, southern India: Geological characterization, palaeoenvironmental history, and geomorphological setting

Sethumadhav, M.S. and Gunnell, Yanni and Ahmed, Mohamed Muzamil and Chinnaiah (2010) Late Archean manganese mineralization and younger supergene manganese ores in the Anmod–Bisgod region, Western Dharwar Craton, southern India: Geological characterization, palaeoenvironmental history, and geomorphological setting. Ore Geology Reviews, 38 (1). 70 - 89. ISSN 0169-1368

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Abstract

The field setting, mineralogical, geochemical, genetic and depositional features of Late Archean metasedimentary manganese, as well as Cenozoic supergene manganese and ferromanganese ores, along the ~75km long linear tract of the Anmod–Bisgod region in the Western Dharwar Craton, southern India, are described. The 2700Ma metasedimentary manganiferous formation is underlain by stromatolitic limestone/dolomite and quartzite/arenite and also occurs within the former. The older quartzite/arenite, which contains redox-sensitive detrital pyrite and uraninite as well as thucolite, indicates sedimentation under anoxic to oxic transitional palaeoenvironmental condition, whereas the younger stromatolitic limestone/dolomite indicates development of oxygen in the depositional environment. The manganese ore types have been classified into three categories, one of which is a Mn-rich duricrust once capping the Late Archean manganiferous formation. It formed during a Cenozoic lateritic weathering event and was eroded in response to crustal uplift. Perhaps uniquely, clastic deposits of the eroded Mn-duricrust occur in mineable quantities in the form of fluvial palaeochannel fills. These cryptomelane-rich supergene ores are also suitable for radiometric dating. Knowing their age would help to constrain the timing of Mn-duricrust formation and, indirectly, the regional weathering event responsible for the extensive laterite occurrences of southern India.

Item Type: Article
Uncontrolled Keywords: Late Archean palaeoenvironment, Manganiferous formation, Lateritic manganese ores, Palaeochannel, Cenozoic weathering, India
Subjects: F Earth Science > Geology
Divisions: Department of > Earth Science
Depositing User: lpa manjunath user
Date Deposited: 08 Jul 2019 10:35
Last Modified: 08 Jul 2019 10:35
URI: http://eprints.uni-mysore.ac.in/id/eprint/4908

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