The Department of Earth & Environmental Science

University of Pennsylvania

Invites you to attend a EES Seminar Series

Friday, September 13, 2024 - 3:00 PM

"A Global Tour of Iron Speciation in Deep-sea Hydrothermal Plumes"

Hydrothermal venting occurs in every ocean basin on Earth. The physical and chemical gradients created by the mixing of deep ocean water with vent fluids and near-vent materials generate populations of particles with complex compositions. A subset of these particles have characteristics that promote long-range transport, making them of interest for the delivery of micronutrients - such as iron - to locations where they limit productivity. In this contribution, the past decade of sample-return studies of deep-sea hydrothermal particles will be summarized and data from three new sites will be reported. Particles were collected by in situ filtration, shipboard filtration, and sediment traps from buoyant and neutrally buoyant plumes at differing distances from vents (1 m to 4300 km). The primary data types for this meta-analysis are synchrotron microprobe iron X-ray absorption spectroscopy and diffraction, as well as X-ray and electron microscopy.

Together these observations inform the size and morphology of hydrothermal plume particles, the mineralogy of crystalline phases, and phase identification for poorly crystalline iron-bearing phases. Previous findings for three vent fields (East Pacific Rise 9N, East Pacific Rise 15S, and Eastern Lau Spreading Center) will be interpreted within the context of new iron speciation and mineralogical data from Earth’s deepest explored hydrothermal field (Beebe Vents, Piccard hydrothermal field), as well as ultramafic-hosted vents of the Mid-Cayman Rise (Von Damm) and Mid-Atlantic Ridge (Rainbow). Common and unique features of plume particles that arise from gradients in water depth, vent fluid temperature, and lithology will be discussed.

We’ll close with implications of the work for exploration of ocean worlds and development of next generation synchrotron instrumentation.

Dr. Brandy Toner

Professor

Department of Soil, Water, and Climate

University of Minnesota

Brandy Toner is a Professor in the Department of Soil, Water, and Climate at the University of Minnesota. Her scientific discipline is geochemistry. There are many types of geochemists and Brandy's research focuses on the chemical form and mobility of metals in the Earth surface environment. This is important because metals are both necessary for life (like iron) and toxic (like arsenic or mercury). Brandy is a first generation college student and currently the only woman Professor in her department, but hopefully, that will change soon! As a kid, Brandy wanted to be an astronaut but motion sickness was a serious problem. Instead of space exploration, she was a NASA Postdoctoral Fellow and some of her research takes her on expeditions deep underground or deep underwater.