Sedimentary rhythms occur on various timescales, ranging from astronomical Milankovitch cycles, to seasonal, daily and sub-daily (tidal) cycles. Deciphering these rhythms in deep-time Precambrian sedimentary archives could vastly improve our understanding of sedimentary environments under conditions dramatically different from today’s, and even different from those known through the Phanerozoic (for example, low level of free oxygen in the atmosphere, no complex life, faint young sun, onset of plate tectonics). Precambrian sedimentary cycles are crucial for quantitatively constraining the history of our solar system, including the Earth-Moon interactions. Despite the potential for groundbreaking insights, identifying Milankovitch and tidal cycles in the Precambrian record is challenging due to limited time control (for example, lack of radioisotopic dates) and a scarcity of high-quality records.
In this project, we try to decipher the sedimentary rhythms preserved in the 3.2 Ga Moodies Group of the Barberton Greenstone Belt of South Africa and Eswatini. We use a combination of field data and newly drilled cores from the ICDP BASE project. The close to perfect continuity of these cores enables us to study the sedimentary rhythms over longer time intervals than previously possible with field data alone.
At the University of Halle-Wittenberg, we study the sedimentary environments and processes preserved in the Moodies Group. This approach allows us to reconstruct the Paleoarchean sedimentary environments, analyze the behavior of fluvial and shallow marine systems in a world without macroscopic life and with a different atmospheric composition, explore the influence of tides on coastal areas, and understand how these environments may have supported the early spread of life. We focus on short-term sedimentary rhythms, such as variations in fluvial discharge and tidal current strength.
By investigating sedimentary dynamics in more complete distal successions, we support our colleagues at the University of Münster in their quest to identify longer-scale cyclicities, including potential Milankovitch cycles, in the Moodies Group.
By investigating sedimentary dynamics in more complete distal successions, we support our colleagues at the University of Münster in their quest to identify longer-scale cyclicities, including potential Milankovitch cycles, in the Moodies Group.
Partners & Funding
