2023-2024: Study of the Earth’s Deep Interior: Dominique Weis

Dominique Weis
Pacific Center for Isotopic and Geochemical Research;
University of British Columbia


Director of the Pacific Center for Isotopic and Geochemical Research, a major analytical facility serving the needs of academics, government and industry, Professor at the University of British Columbia, Vancouver, Canada. Dominique Weis is a leader in the innovative use of trace element and isotope geochemistry. She is widely respected "for the elegance, precision, and impact of her geochemical studies of the Earth from large igneous provinces to the environment" (AGU Fellow citation). Her research aims to (1) determine the origin, source and pathways of mantle plumes and their variations through time; (2) apply geochemical tools to resolve Indigenous-led questions and (3) improve our understanding of the human impact and study metal distribution in the environment. Dr. Weis has published more than 240 peer-reviewed articles. 

The impact of Weis’ work in the geochemistry of the Earth’s mantle and the application of geochemistry in the environment can be measured in terms of academic awards (Canadian Research Chair Tier I 2002-09-16, 2015 André Dumont Career Award, AGU Fellow 2010, Geochemical Fellow 2011, FRSC 2016), nominations (2015 YWCA Woman of Distinction), invited lectures (including Daly Lecturer 2010, ECORD Distinguished Lecturer 2010-2012, Scugog Lecturer 2017, 2020 Mentorship Medal from the Canadian Federation of Earth Sciences) and research grants. She contributes to science policy issues (including at the European Union level) and public issues (impact of the Olympic Games in Vancouver, state of the environment in BC). In addition to research impact, Weis and the PCIGR are closely involved in the training of HQP and with industrial partners in the technology transfer and application of novel isotopic techniques for solving Earth and environmental problems. She is the Director of the Multidisciplinary Applied Geochemistry Network, an industrial-stream NSERC CREATE initiative devoted to young scientists (>70 trainees at 5 Canadian universities). She was the main organizer of the highly praised Goldschmidt conference in Vancouver (~2000 delegates from 49 countries). 

Abstract: Mantle Plumes as Compositional Probes of Earth’s Interior

The mantle represents 84% of Earth’s volume. It plays a critical role in the dynamics of the Earth and many essential processes that shape our planet, including convection, crustal formation and recycling, and the planet’s heat and volatile budgets. Seismic wave velocity variations provide evidence for the presence of various mantle reservoirs with differences in temperature and/or composition. The lower mantle, or part of it, is a reservoir that contains compositionally distinct material, including recycled and potentially ancient primitive components not available anywhere else. Mantle plumes originate at different depths, from shallow upwellings in the upper mantle to deeply sourced plumes that rise from near the core-mantle boundary (CMB) at ~2800 km. As such, they are invaluable tools to help answer many unresolved questions about mantle composition and its coupling to geodynamics, both today and throughout geologic time. 

In this lecture, we will focus on the applications of geochemistry and isotopic analyses, which are essential tools for documenting mantle heterogeneity, and examine three major, well-studied plume systems with high magmatic fluxes in three different tectonic settings: Hawai’i, Galápagos, and Kerguelen. Hawai’i has been quoted as the archetype of mantle plumes. We will show that it is in fact quite unique in many of its characteristics (e.g., plume flux, evolution through time, and chemical components).

New perspectives on the geochemical composition of the mantle have recently been developed from advancements in analytical techniques and novel isotopic systems, allowing the resolution of smaller isotopic variations in ocean island basalt samples. These new techniques and isotopic systems shed light on the presence, source, and age of heterogeneities in the deep mantle. Coupled to geodynamic studies, modern isotopic data continues to reveal the complex nature of mantle chemical reservoirs through time and the complicated interplay between these reservoirs and the physical processes that govern internal Earth dynamics.