Developing continuous volcano-stratigraphies across the South Atlantic Transect: NERC UK-IODP Moratorium support for Aled Evans - IODP Expedition 393

Mid-Ocean Ridges are the most extensive magmatic system on Earth, producing 75 per cent of the planet's volcanism with the resulting processes governing the architecture of at least two thirds of the surface of our planet. A representative stratigraphic record of the order, eruption style, and extent of mid-ocean ridge lava flows is required to understand seafloor spreading, a fundamental process in plate tectonics.

As access to ocean crust is restricted to scientific ocean drilling and the use of submersibles, physical and chemical information on the nature of upper ocean crust is limited to recovered rock. However, during scientific ocean drilling, the proportion of recovered rock compared to the length drilled is both generally low and highly variable. These recovered samples have been shown to reflect a bias towards stronger, more competent lithologies, with weaker, more incompetent rock types underrepresented. This highlights that recovered physical samples from scientific expeditions display only a partial representation of reality.

Integration of recovered physical drill cores with quantitative geophysical wireline logging data can provide representations of the volcanic stratigraphy at drilled sections of mid-ocean ridges. The unification of a physical but incomplete dataset, with a complete but abstract quantitative dataset, provides constraints on biases within recovered samples.

An understanding of the bias reflected in recovered samples is essential to avoid inaccurate estimations of key planetary processes such as the extent of heat, chemical, and mass exchange between ocean crustal rocks and seawater. The understanding and quantification of these exchanges is necessary in evaluating the role of mid-ocean ridges on long-term global geochemical cycles (e.g., C, H2O) and the wider habitability of the planet.

International Ocean Discovery Program (IODP) Expeditions 390 and 393 will drill a transect of six sites across the South Atlantic, recovering ocean crust formed at the Mid-Atlantic Ridge between 7 and 61 million years ago. I will integrate observations of physically recovered core samples with quantitative geophysical wireline logging data from these drillholes to reconstruct the volcanic history along a transect of the aging western flank of the southern Mid-Atlantic Ridge . The resulting stratigraphy will provide an essential foundation for subsequent investigations and quantifications of planetary processes at mid-ocean ridges.