Dear Colleagues, On behalf of my co-conveners Drew Syverson and Serhat Sevgen, I invite you to please consider submitting an abstract to session 12d - Seafloor hydrothermal processes and their impacts on the modern and ancient Earth<https://conf.goldschmidt.info/goldschmidt/2026/meetingapp.cgi/Session/8648> (session description pasted below). The 2026 Goldschmidt Conference will take place in Montreal, Canada (woohoo, eh!) 12-17 July, and the abstract deadline is 26 February 2026. I hope that we can continue the tradition of this session as a forum for compelling hydrothermal geochemistry at the Goldschmidt conference. I look forward to seeing many of you there! Best regards, Ben, Drew, and Serhat 12d - Seafloor hydrothermal processes and their impacts on the modern and ancient Earth Seafloor hydrothermal systems have profoundly influenced Earth’s biosphere, lithosphere, hydrosphere, and atmosphere throughout Earth history. However, their very nature within the oceanic crust drastically limits the temporal extent of direct geologic observations of their existence. Thus, attempts to correlate seafloor hydrothermal processes with biological evolution, global elemental budgets, and global redox states throughout Earth history generally require interdisciplinary efforts that integrate studies of modern systems, interpretations of the geologic record, novel laboratory experiments, and numerical models. In this session, we intend to host a forum for presenting and integrating these various sets of observations in order to focus the community’s efforts on answering key questions regarding the role of seafloor hydrothermal processes in the Earth system. In particular, we invite contributions focusing on seafloor measurements of modern hydrothermal systems; studies of recovered oceanic drill core, obducted oceanic lithosphere, or proxy records in ancient sedimentary rocks; experimental exploration of seafloor (bio)geochemical interactions; and integrative numerical models that expand the spatiotemporal scales of these field and experimental observations. Specific focuses could include the role of seafloor hydrothermalism in carbon and other elemental cycles, studies of the linkages between hydrothermal alteration, crustal mineralogy, and seawater geochemistry, and the relation between hydrothermal systems and the tempos and milestones of biological evolution. Keynote Speaker: Susan Lang, Woods Hole Oceanographic Institution Confirmed Invited Speaker: Alexander Diehl, University of Bremen Associate Professor Department of Earth, Energy, and Environment University of Calgary 550 Earth Sciences, 2500 University Dr NW Calgary, AB T2N 1N4 Canada https://www.ucalgary.ca/reactive-transport/research Associate Professor Department of Earth, Energy, and Environment University of Calgary 550 Earth Sciences, 2500 University Dr NW Calgary, AB T2N 1N4 Canada https://www.ucalgary.ca/reactive-transport/research