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2019 Birdsall-Dreiss 1. Chasing Helium: Mantle-to-Surface Connections to Water
Quality and Geomicrobiology. The discovery of oceanic
Distinguished Lecturer black (and white) smokers revolutionized our understanding of
mid-ocean ridges and led to the recognition of new organisms
and ecosystems resulting from mixing of fluids. Continental
smokers, defined here to include a broad range of carbonic
springs, hot springs, and fumaroles that vent mantle-derived
Laura J. Crossey is a professor in the fluids in continental settings, exhibit many of the same
Dept. of Earth & Planetary Sciences at the processes of heat and mass transfer and ecosystem niche
University of New Mexico (UNM). She differentiation. The application of noble gas geochemistry
received her bachelor’s degree in geology at (specifically helium isotope [ He/ He] analyses) indicates
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Colorado College (1977), master’s degree at widespread mantle degassing in perhaps unexpected tectonic
Washington University in St. Louis (1979), locales including the western U.S., the Great Artesian basin
and Ph.D. from the University of Wyoming of Australia, the Western Desert of Egypt, and the Tibetan
(1985). She joined the UNM faculty in 1986 Plateau. Variations in the mantle helium component measured
and was the first woman in the department in groundwaters correlate best with low seismic-velocity
Laura J. Crossey to be tenured, promoted to full professor, domains in the upper mantle and with abrupt lateral contrasts
and serve as chair. in mantle velocity rather than crustal parameters such as strain
rate, proximity to volcanoes, crustal velocity, or composition.
Crossey’s research group explores applications of low-temper- Microbial community analyses applied to several of these
ature geochemistry to problems in hydrochemistry, diagenesis, areas indicate that these springs can host novel micro-
geomicrobiology, and geothermal processes. Her approach organisms. Our work yielded the first published occurrence
combines field examination of modern laboratory analysis as of chemolithoautotrophic Zetaproteobacteria in a continental
well as core and outcrop study to evaluate paleohydrology, setting. These observations led to two linked hypotheses.
spring sustainability, and reservoir/aquifer characteristics. (1) Mantle-derived volatiles transit through conduits in extend-
Related activities include geoscience outreach, K–12 outreach, ing continental lithosphere preferentially above and at the
science education research, and programs to increase the edges of mantle low-velocity domains. (2) Elevated concentra-
participation of underrepresented groups in science. She is tions of CO and other constituents ultimately derived from
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a leader on the National Science Foundation–funded New mantle volatiles drive water-rock interactions and heteroge-
Mexico Alliance for Minority Participation Award and has neous fluid mixing that help structure diverse and distinctive
served on numerous review panels and volunteer boards. microbial communities. This recognition of the small volume
but chemically potent “lower world” contributions to ground-
A GSA member since 1997 and Fellow since 2012, Crossey water systems has implications for topics as diverse as tecton-
has served as president of the Sedimentary Geology Division, ics, fluid conduits, water quality, and microbial ecosystems.
Technical Program Chair for the Rocky Mountain Section,
associate editor for GSA Bulletin, Geochimica et Cosmochimica 2. Hydrochemistry and Geoscience Education at Grand
Acta, and Applied Geochemistry, and was editor of SEPM Canyon and Beyond: Who Knew Groundwater Hydrology
(Society for Sedimentary Geology) Special Publications. Could Be So Complicated? Springs and associated riparian
She was awarded lifetime membership in the New Mexico environments provide critical habitats for aquatic and
Geological Society. She and her husband, Karl Karlstrom, were terrestrial wildlife in the Grand Canyon region and drinking
awarded an Outstanding Achievement Award by the American water for Grand Canyon National Park. Grand Canyon springs
Institute of Professional Geologists in 2015 for designing and are fed by world-class karst aquifer systems on the Colorado
building the Trail of Time, a geoscience exhibition at the Grand Plateau, but increasing pressure on groundwater resources
Canyon (funded by the National Science Foundation, and recog- from climate change, mining, and other development poses
nized as Best Wayside Exhibit by the National Association for major challenges to resource managers. The shallow and deep
Interpretation in 2011). karst systems of the region interact in ways that are revealed
by recent studies. General hydrologic models for the Colorado
Crossey’s research on carbonic springs has taken her to the Plateau aquifers highlight the importance of recharge areas
Great Artesian basin of Australia, the Western Desert of Egypt, (“springsheds”) for water supply. Ongoing work helps explain
and the Tibetan Plateau. these complex relationships using multiple tracer methods.
A robust monitoring and geochemical sampling program
Institutions can schedule a lecture on one of the topics provides data for understanding the sustainability of spring-
described below at community.geosociety.org/hydrodivision/ fed water supplies for anthropogenic use. Geochemical studies
birdsall/about2019. (Crossey is also happy to present brown of spring waters (including dissolved gases) have identified
bags or visit with faculty, staff, and/or students on topics such as the importance of mantle-derived volatiles and CO that
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inclusion and diversity in STEM.) contribute dissolved salts and other products of water-rock

10 GSA Today | December 2018