全球变化知识资源中心

India has perhaps the richest Paleoarchean to Paleoproterozoic crustal components on Earth (Miller el al., 2018). Notwithstanding this, much of the Indian subcontinent remains unexplored compared to other ancient cratons in North America, Australia, Brazil and Africa. There are five Archean cratonic nuclei in India (the Aravalli, Bundelkhand, Singhbhum, Bastar and the Dharwar) with well-preserved Proterozoic supracrustal sequences. This paper critically reviews the Paleoarchean to Paleoproterozoic supracrustal record of the Indian subcontinent with special emphasis on the Archean-Paleoproterozoic transition, which is generally placed at similar to 2.5 Ga based on the emplacement age of the Great dyke of Zimbabwe. In general, the Archean-Paleoproterozoic transition in Indian cratonic blocks is associated with high continental freeboard condition. Unlike North America, South Africa and Western Australia, the Indian cratonic blocks (except Bastar) are devoid of Paleoproterozoic glacial diamictite (Mazumder et al., 2015). However, similar to the Pongola Supergroup of South Africa, there are evidences of Neoarchean glaciation in Dharwar (Ojakangas et al., 2014). In contrast to the global scenario of extensive development of BIF across the Archean-Paleoproterozoic transition, the Indian Paleoproterozoic successions are devoid of Banded Iron Formation (BIF) (except the 1.85 Ga old BIF in Bundelkhand). In contrast, the majority of the Indian BIFs are of Paleoarchean or Neoarchean age. Thus, the geodynamic and supracrustal data collected from five Indian Archean cratonic blocks do not correspond uniquely and precisely to a global change in tectonic style, onset of Neoarchean global magmatism and rifting, or lithostratigraphic and environmental changes suggested across the Archean-Paleoproterozoic transition (Van Kranendonk et al., 2012). Therefore, a revision and redefinition of the Archean-Proterozoic boundary is outstanding.

This article is part of a special issue entitled: Archean Earth Processes; Edited by. Rajat Mazumder and Patrick Eriksson.