Sethumadhav,M.S., Gunnell,Y., Ahmed,M.M. 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, 70-89.

『インド南部の西ダワール・クラトンのアンモド・ビスゴド地域における始生代後期のマンガン鉱化作用と若い浅成マンガン鉱石：地質学的特徴と古環境史と地形学的背景』

『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 〜75 km long linear tract of the Anmod-Bisgod region in the Western Dharwar Craton, southern India, are described. The 2700 Ma 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 palaochannel 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.

Keywords: Late Archean palaeoenvironment; Manganiferous formation; Lateritic manganese ores; Palaeochannel; Cenozoic weathering; India』

1. Introduction
2. Geological setting
3. Manganese and ferromanganese ore types
4. Mode of occurrence
　4.1. Metasedimentary manganese ore (ore type 1)
　4.2. Infiltration-type non-colloform and colloform manganese ores (ore types 2 and 3)
　4.3. Detrital ferromanganese ores (ore types 4 and 5)
5. Mineralogy
　5.1. Metasedimentary manganese ore
　5.2. Infiltration-type non-colloform and colloform manganese ores
　5.3. Detrital ferromanganese ores
6. Geochemistry of the metasedimentary manganese and supergene manganese and ferromanganese ores
　6.1. Typology of sampled Mn-ore facies
　6.2. The late Archean metasedimentary manganiferous formation
　6.3. The metasedimentary manganese ore
　6.4. The supergene manganese and ferromanganese ores
7. Depositional environment of the Late Archean manganiferous formation
8. Mode of formation and present day disposition of supergene manganese and ferromanganese ores
9. Conclusion
Acknowledgements
References

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