Dating the oldest greenstone in India: A 3.51-Ga precise U-PbSHRIMP zircon age for dacitic lava of the southern Iron Ore Group, Singhbhum craton

摘要

This article reports a precise 3506.8 +/- 2.3-Ma U-Pb SHRIMP zircon age for dacitic lava in a well-preserved low-grade metamorphic and low-strained greenstone belt succession of the southern Iron Ore Group, Singhbhum craton, India. This age makes the succession the oldest-known greenstone belt succession in India and one of the oldest low-strain greenstone successions in the world after the 3.51-Ga Coonterunah Group of the Pilbara craton, Western Australia, and the moderately deformed 3.54-Ga Theespruit Formation of the Barberton Greenstone Belt, Kaapvaal craton, South Africa. The geochemical composition of the dacitic lava and related volcanic rocks suggests that they formed in a volcanic arc setting. The succession also contains a major similar to 120-m-thick oxide facies banded iron formation that distinguishes it from the slightly older successions of the Pilbara and Kaapvaal cratons. This banded iron formation may well be one of the oldest and most well preserved, and together with associated volcanics, it may have immediate implications for understanding > 3.5-Ga surface and tectonic processes on Earth.