Deep-sea sediments house diverse communities of biota adapted to complete darkness and the scarcity of electron donors. Yet, given the vastness of the global abyssal plains and the scattered and string of pearl-like distribution of hadal trench and continental margin environments, marine sediments are key reactors of some element cycles. Authigenic carbonates sequester carbon, while pyrite and phosphate minerals sequester iron, sulfur, and phosphorus, respectively – minerals representing some of the dominant sinks for these key elements of life. While most biogeochemical processes proceed at slow pace in the deep sea, the chemosynthesis-based environments at methane seeps and hydrothermal vents are pressure cookers of primary productivity among the deep-sea ecosystems, ecosystems that otherwise rely of the leftovers of the euphotic zone. This session will emphasize the significance of authigenesis for element cycling, addressing the role of biologic activity in carbon, iron, sulfur, and phosphorus cycling in ancient and modern deep-sea environments. We invite contributions from all fields of environmental science including but not limited to geomicrobiology, marine biology, marine geology, mineralogy, and paleontology.