Spectroscopic Investigations and Mineral Chemistry of Dunite from the Sargur Supracrustals (3 Ga) Greenstone Belt: Implications to Terrestrial Analogues for Lunar and Martian Dunite

Abstract

Archean Serpentinised dunite is important not only for understanding the evolution of the ultramafic deposit of magnesium, but also serves as a possible sink material for the carbon dioxide sequestration. Future anti-pollution measures may include sequestering of waste CO2 as magnesite (MgCO3) by processing ultramafic rocks to obtain reactable Mg. For the first time, the Raman spectroscopic investigation of dunite is presented from the Karya, Sargur supracrustals (3Ga) Greenstone Belt. The Raman spectra of the sample reveal abundant presence of serpentine. Polymorphs of serpentine: lizardite, antigorite and chrysotile exhibit typical intense band at 685−692 cm−1 in the Raman spectrum. The Raman peaks in this study also indicates the presence of chromite and magnesite. The lunar dunite 72415, one of the oldest lunar samples of the Mg-suite, contains chromite symplectites indicative of crystallization at 40−50 km rather than at a shallow depth of <1 km, also having a olivine content of about 85%. The present study showed the dunite has about 85% olivine, which is almost identical to the Martian dunite, meteorite Northwest Africa (NWA) 2737 is the second known chassignite, an olivine-rich igneous rock with mineral compositions and isotopic ratios that suggest it formed on Mars. NWA 2737 consists of ~ 85% vol. The present study on the Karya dunite of Sargur supracrustals (3 Ga) greenstone belt, Western Dharwar Craton Karnataka, indicates a possibility of using this as a terrestrial analogue material for improving the Martian surface mineralogy and occurrence of hydrous minerals and life support system in Mars.