News

Nicole Williamson, Dominique Weis

The deep, ‘ambient’ pacific mantle sampled by the Kea side of the Hawaiian plume, which was thought to be relatively chemically homogeneous, contains chemical heterogeneities, according to a new UBC EOAS research published in Geochemistry, Geophysics, Geosystems.

The Hawaiian Island volcanoes record 6 Ma (mega annum; millions of years) of potentially deep mantle chemistry and form two parallel volcanic chains that are geochemically unique, named Loa and Kea. Volcanoes from the Loa trend have more “enriched” isotopic compositions, indicative of the presence of recycled surface materials in their source, whereas volcanoes from the Kea trend tend to have average deep Pacific mantle compositions.

To explore the source and origin of mantle heterogeneities in Hawaiian lavas, lead researcher Nicole Williamson (Ph.D. Candidate, Pacific Centre for Isotopic & Geochemical Research) and her co-authors Dominique Weis and Julie Prytulak (Durham University) measured thallium (TI) isotopic composition in Hawaiian basalt samples. Tl isotopes (205Tl and 203Tl) are unequally distributed across Earth's chemical reservoirs and can show large concentration contrasts, for example between pelagic sediments (>>100 ng/g) and the Earth's mantle (<1 ng/g).

Thallium isotopic compositions in Hawaiian lavas compared to radiogenic isotopes from Williamson et al, 2021.
The scientists found that among other indicators, the heavier Tl isotopic compositions measured in some volcanoes of the Kea geochemical trend might co-vary with oxygen isotopes, suggesting that their Tl compositions could also result from the presence of recycled surface materials in their source. “The Loa side of the Hawaiian plume typically erupts more chemically heterogeneous lavas, but in the case of thallium isotopes, it’s the Kea side that is more diverse in composition,” says Williamson.

The study shows that the mantle source of both the Loa and Kea geochemical trends likely contains materials recycled through the mantle, which is significant because thus far the Kea volcanoes have shown fairly uniform isotopic compositions representative of the average, deep Pacific mantle.

Anaïs Orsi is an Assistant Professor in the Department of Earth, Ocean and Atmospheric Sciences (EOAS) at UBC. Her research focuses on polar climate variability using tracers found in ice cores. Today, the Arctic is the region that is warming the fastest on Earth. Anais’s work is to provide context to the current trend by reconstructing the climate of the recent past (several thousand years) using indicators found in ice cores. These indicators can be the thickness of an annual layer of snow, the presence of an ice lens indicating melting, the isotopic composition of the water that snow is composed of, or simply the temperature inside the ice sheet. All of these indicators give a complementary information of what the past climate might have looked like, and help put the recent trends in context. This work has led her to repeatedly visit polar regions, in Greenland and Antarctica, in the search for clues of past climates.

Prior to joining UBC, Anaïs completed her PhD at the University of California San Diego, and subsequently worked as a research scientist at the LSCE (Climate and Environmental Science Laboratory) in France. Her work has been distinguished by several prizes, including the International Rising Talent of the L’Oreal-UNESCO foundation for women in Science.

Randy Smallwood holds a geological engineering degree from the University of British Columbia and is one of the founding members of Wheaton Precious Metals. In 2007, he joined Wheaton full time as EVP of Corporate Development, primarily focusing on growing the company through the evaluation and acquisition of streaming opportunities. In January 2010, he was appointed President, and in April 2011, he was appointed Wheaton's CEO.

Mr. Smallwood originally started as an exploration geologist with Wheaton River Minerals Ltd., and in 2001, was promoted to Director of Project Development, a role he held through the 2005 merger with Goldcorp (which has since merged with Newmont). Mr. Smallwood was an instrumental part of the team that built Wheaton River/Goldcorp into one of the largest and, more importantly, most profitable gold companies in the world. He is now focused on continuing to add to the impressive growth profile of Wheaton and leading the World Gold Council as its current chair.

Kohen Bauer

Ocean deoxygenation during the Mesozoic Era was much more rapid than previous thought, with CO2 induced environmental warming creating ocean ‘dead zones’ over timescales of only tens of thousands of years.

The research from University of British Columbia (UBC) and University of Hong Kong (HKU) Earth scientists paints a new picture of severe ocean deoxygenation events in our planet’s geologic history. 

“Physical drivers, in particular ocean warming linked to volcanic activity during the Cretaceous Period, played key roles in triggering and maintaining oceanic anoxia,” says lead researcher Dr. Kohen Bauer, who began the work while at UBC and completed the study with HKU’s Department of Earth Sciences.

“The same mechanisms are also critically important drivers of modern ocean deoxygenation and expanding marine dead zones. Today, in addition to volcanoes releasing CO2 into the atmosphere, humans are as well.”

Previous research tended to focus on the role ocean nutrient cycles played in causing so called ‘dead zones’—a process that would have driven ocean deoxygenation over much longer timescales of hundreds of thousands of years. However, it’s now clear that massive volcanism and its associated feedbacks was a more direct trigger for the rapid development of oceanic anoxia.

The research delved into the causes of Oceanic Anoxic Event 1a — an interval 120 million years ago when large swaths of Earth’s oceans became anoxic. Those conditions likely persisted for almost a million years, causing climate perturbations, and biotic turnover.

The scientists reconstructed the period’s environmental conditions using novel geochemical methods and ancient sediments deposited in both the paleo-Tethys and paleo-Pacific oceans. 

“Mesozoic oceanic anoxic events are some of the most important analogs for unlocking lessons about warm-Earth climate states in the geological record,” says UBC’s Dr. Sean Crowe, author on the paper and Canada Research Chair in Geomicrobiology with UBC’s departments of Microbiology and Immunology, and Earth, Ocean and Atmospheric Sciences.

“These events provide enormous potential to help us better understand the sensitivity of the Earth system to perturbations in global biogeochemical cycles, marine biology, and climate on timescales relevant to humankind.”

The paper was published in the journal Geology.

Stephanie is a sea-going physical oceanographer. She is interested in large-scale circulation and the ocean's role in the climate system and the inter-relationships between various components of the oceanic circulations at different times.

She approaches her research both through observational & theoretical perspectives. She uses targeted field observations, observational data analysis, idealized process modeling, analytical analysis & lab studies. Her main aim is to observe real-world systems, identify the important physical processes generating individual phenomena, and reduce their complexity to a model which is useful.

She’s specifically interested in:

• Arctic oceanography, and the mixing of different types of waters in that ocean
• Southern ocean dynamics
• The role of “eddy fluxes” in the western boundary
• Geophysical fluid dynamics