WALKING THE CONTACT UNDER WATER: GEOLOGIC MAPPING OF SUBMARINE VOLCANO HISTORIES

Volcanoes are dynamic geological structures that provide insights into many different Earth processes, such as the formation and eruption of magma, the structural and tectonic controls on magmatism, the composition of Earth’s interior, landscape evolution, and the outgassing history of Earth. Fundamental to understanding the magmatic and eruptive histories of a volcano requires an inventory and spatial distribution of eruption deposits and associated tectonic features. This includes geologic mapping of lava flow fields, comprised of the products of individual eruptive episodes, as well as identification of eruptive vents and pyroclastic deposits. While true for all volcanoes, regardless of their setting, some volcanoes, such as submarine ones, present greater challenges for geologic mapping at the scale necessary to adequately determine important parameters such as individual eruption deposit size, thickness, distribution and morphology; volcanic histories during and between eruptions; conditions that control eruption frequency and eruption style; and magma formation, delivery, storage, and temporal evolution within individual magmatic systems. Few submarine areas have been mapped at this scale, beyond the limits of only the most recent eruption. This presentation will focus on examples of work by our group, and that of Dave Clague’s, who have worked hard to develop and refine tools and methods for geological mapping at submarine volcanoes on mid-ocean ridges, as well as at other tectonic settings, primarily in the Pacific Ocean. These efforts have successfully developed and used detailed multi-eruption histories to explore the factors that govern volcanism in Earth’s most prolific volcanic terrain, including not only geological mapping, but also timescale assessments, eruption conditions and volcanic facies characterization, changes in magmatic chemistry over time, and crustal magma delivery and recharge.