Black shale and the formation and evolution of the habitable Earth

The deposition of black shales records critical stages in the formation and evolution of a habitable Earth, encompassing the convergence and breakup of supercontinents, large-scale climate changes, fluctuations in ancient ocean redox conditions, and biological radiations and extinctions. The formation of black shales is typically associated with marine environments. It not only reflects the interactions between oceanic redox states and biological evolution throughout geological history, but also preserves information on the cycling and transformation of essential life elements-such as nitrogen, phosphorus, and iron-between the biosphere and the abiotic environment. This study systematically reviews the sedimentary characteristics and depositional models of black shales, as well as their implications for the biogeochemical cycling of key bioessential elements and the reconstruction of paleo-ocean redox conditions. Additionally, it explores the impact of black shale weathering on the global carbon cycle and environmental pollution. Finally, the paper summarizes the current challenges in using black shales for studies on Earth’s habitability and discusses potential future research directions, providing insights for further investigations.