Earth, Atmosphere & Environment Sciences
Title : | The Archean atmosphere and oxygenation of early Earth, evidence from geochemistry and Cr isotopic composition of Banded Iron Formations from the Dharwar Craton, Southern India |
Area of research : | Earth, Atmosphere & Environment Sciences |
Principal Investigator : | Dr. Sameer Ranjan, CSIR- National Geophysical Research Institute, Telangana |
Timeline Start Year : | 2023 |
Timeline End Year : | 2025 |
Contact info : | sameerranjan.18@gmail.com |
Details
Executive Summary : | The Earth's evolution after accretion involved multiple geochemical changes, including the formation of crust, mantle, core, and atmosphere. The availability of running water and atmospheric oxygen is crucial for sustainable life on modern Earth. The main uncertainty for Archean oxygenation is the major sources of oxygen, abiotic or biotic. The Archean environment was hostile and the type of life form was highly debated. Most oxygen on modern Earth comes from biotic sources, leading to a critical question about when past biotic oxygen production surpasses abiotic sources. The chemically precipitated sedimentary rocks, the Banded Iron Formation (BIF) and chert, provide direct evidence for the redox conditions of the Archean ocean. The BIF horizons are classified into two types, the Algoma type and the Superior type. The alternate bands in the BIF represent the ambient ocean chemistry, influenced by seasonal climatic changes and surrounding environment. The investigation of these chemically precipitated rock records can shed light on the Archean atmosphere, weathering conditions, and oxygen availability. One key question is the oxygenation state before the Great Oxygenation Event (GOE), whether O₂ was well mixed and evenly distributed or existed as O₂ oases concentrated in zones of enhanced biotic input. This study aims to use a novel proxy involving geochemistry and Cr isotopic systematics of the Archean BIFs from the Dharwar Craton to understand their formation and the redox conditions of the Archean ocean. The study will investigate alternating layers from representative BIF, chert, and shale samples of different age for major and trace element concentrations. |
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