The Barberton Greenstone Belt: A unique window into Paleoarchean life
- Martin Homann
University College London
The ca. 3.55 to 3.20 Ga Barberton Greenstone Belt (BGB) provides a rare window into diverse and widespread Paleoarchean microbial ecosystems, including a large variety of convincingly biological, geochemical, macro- and microscopic traces of early life. The high spatial and temporal resolution of this ~15 km thick volcano-sedimentary succession and the wealth of preserved biosignatures from marine, coastal, fluvial, hydrothermal, and planktonic settings is truly remarkable. The most widespread and arguably also oldest traces of ancient life in the BGB are remnants of microbial mats and biofilms, which occur throughout the entire stratigraphy, mainly confined to carbonaceous cherts of the Onverwacht Group and the sandstones and conglomerates of the Moodies Group. Surprisingly, however stromatolites are extremely rare in the BGB and only known from a few isolated localities. The fossil mats of the 3.22 Ga Moodies Group represent a particularly widespread and well-preserved record of Paleoarchean life and will be discussed in this lecture in great detail. Based on its universal and outstanding geological and paleobiological value the Barberton-Makhonjwa Mountains were inscribed in the UNESCO World Heritage Site register in 2018, which will ultimately help to protect these exceptional outcrops for future studies of Earth's early evolution.
9 фев 2023
