My primary research focuses on the chemistry of Earth and planetary interiors with a particular emphasis on the role of magma generation and magma and fluid - interaction on the differentiation and chemical evolution of terrestrial planets.
I combine experimental techniques and thermodynamical modeling to investigate a range of various processes from magma focusing in the asthenosphere to reactive-cracking in the crust.


Prospective graduate students: I'm always interested to learn about prospective graduate students who have strong academic records, research experience and are interested in pursuing experimental petrology or geochemistry/modeling research. Please send me an email and tell me about your background and why you are interested in my group.

Undergraduate Research Opportunities. Students interested in proposing new projects for an independent study or a senior thesis should contact me in advance so it can be coordinated with the UROP program

Postdocs: I will update this post with Postdoc project positions as they become available. But if you have a great idea for a project and would like to work with me please do send me an email, it is always fun to discuss new project ideas and we can investigate funding options.

New Member

Ashley Morris will be joining us as a new M.Sc. student. She will investigate melt-rock interaction during magma transport.

Upcoming

IODP expedition #396:

Aug-Oct 2021: I have been invited to sail as a Petrologist on the IODP exp#396
@THEU: U professor to sail on expedition sampling the rocks of the seafloor

Graduate school:

October 2021: Emily and I will be participating to the second edition of the International School on Mantle dynamics MEREMA II.

News!

@THEU:

19 July 2021: How 3-D modeling helped U geologists teach during COVID-19.

Goldschmidt 2021:

July 2021: 2nd Virtual Edition.
Co-chair of session 2e.
Presentation with Otto Lang on the behavior of FRTEs in natural mantle lithologies.
Co-author presentation with Juliette Pin, Lyderic France and Laurie Reisberg.

Workshop:

7-10 June 2021: Emily and I participated in the "Extensional Processes Across Tectonic Settings and Time Scales" workshop sponsored by NSF GeoPRIMS. I led the Q&A session "Rifts, Ridges, and the Mantle" on Thursday.

Seminar/outreach:

2 & 3 June 2021: ANU Research School of Earth Sciences school seminar.

13 May 2021: MSc Defense: Otto Lang presented his work on the behavior of First Row Transitions Elements (FRTEs) in natural mantle lithologies (peridotites & pyroxenites)

ACCESS Program: Check out Helen Lindsey's project! Helen is a freshman student and an ACCESS fellow. This spring, Helen worked on xenoliths from Cabo Verde

Seminar/outreach:

4 May 2021: Guest speaker for the Geologists of Jackson Hole
5 March 2021: SUNY Geneseo, NY.

Fundings:

December 2020: I have been awarded a teaching grant from the University of Utah to expand the online petrology resources we started to create this summer to include thin sections and microprobe analyses.

Seminar/outreach:

25 September 2020: University of Nebraska, Lincoln.

Publication:

June 2020: New paper published in Earth Science Review with Rong Xu and Yongsheng Liu on the nature of the mantle source of the Emeishan large igneous province.

Goldschmidt 2020:

June 2020: 1st Virtual Edition
6/23 - Keynote speaker in session 3a
6/24 - Poster presentation with Sarah Hamilton
6/24 - Co-chair of session 3g

Fundings:

June 2020: I have been awarded a ASC PRF DNI grant to study the behavior of immiscible fluids in porous media.

March 2020: I have been awarded an NSF EAR grant to study magma migration in the mantle. More information here.

Publication:

20 January 2020: Our AGU book chapter, with Ananya Mallik & Emily Chin, has been accepted for publication: a fun and productive collaboration between early-career women faculty! The preprint can be downloaded here.

Hooding Ceremony - Blaise Pascal University:

29-31 January: I was invited to participate to the Ph.D. Hooding Ceremony at Blaise Pascal University. I will also present my research at the Laboratoire Magmas et Volcans. After 8 years, I'm glad I finally have the opportunity to come back to the lab I did my PhD in!

New Lab Member:

9 December 2019: The MagMaX Lab gets busier! Elliot Gray has been selected as an UROP Scholar. He will join the MagMaX Lab next semester to study the origin of differentiated Hawaiian xenoliths. Sarah Hamilton also had her UROP project renewed.

Funding:

November 2019: Otto has obtained both a Chapman fund award ($1200) and a GSTAA award ($500) to participate to the MEREMA II graduate school in Italy.

Award:

18 November 2019: Sarah received the Wasatch Gem Society Scholarship.

Workshop:

18 November 2019: Otto has been accepted to the 2020 SIMS Workshop to be held at Arizona State University on Jan 6-8.

AGU 2019:

9 December 2019: Invited talk in the session V030: “Centimeter-scale isotopic heterogeneity preserved in the lower oceanic crust”.

Seminar:

November 1st: University of Iowa.

MinCup2019:

September 2019: Follow us on @MineralCup and vote daily for your favorite mineral.

Funding:

September 2019: Sarah has obtained two small grants for a total of $400 to purchase lab supplies. Congratulation Sarah!

Goldschmidt 2019:

18-23 July 2019: Giulio Borghini and I co-chaired session 06a
Keynote: Andreas Stracke / Invited speakers: Lynne Elkins and Ananya Mallik.
I also presented my recent research published in Nature Geoscience, in session 02c.

Article highlights:

18 July 2019: “a whole ocean-sized range of chemistry in samples totaling about the size of a grain of rice”. Our article is featured in EGU blog.

Press release:

20 May 2019: How Earth's mantle is like a Jackson Pollock painting - UNEWS

Publication:

20 May 2019: Our paper on mantle heterogeneity and melt transport was published today in Nature Geoscience. One sentence summary: highly heterogeneous melts are delivered to the oceanic crust!

New Team member!

I'm very glad to announce that Otto Lang, who will graduate from Fort Lewis College this summer, will join our team next fall for a Master program in the G & G department. He will work on melt circulation in the mantle and the lower crust.

Fundings:

I was selected for the Research Incentive Seed Grant Program by the College of Mine and Earth Sciences. This grant will provide one full year of RA-ship for a future graduate student.

UCUR 2019:

Will presented his research and represented the G&G department at the UCUR 2019 at Weber State University. Well Done!

Publication:

I collaborated in an invited review on the effect of pyroxenite and melt transport on the U-series disequilibrium. The article is now published in Lithos

UCUR & NCUR 2019:

Will got his UROP Project renewed and will present his research at both UCUR and NCUR conferences. Well done Will!

AGU 2018:

Tuesday at 2:45pm, I will reveal the true nature of the depleted mantle. Join me in session V23A - room Liberty M. - abstract.

Seminars:

October 16th: Utah Valley University.
October 18th: Brigham Young University

Publication:

New paper accepted in Geochemistry, Geophysics, Geosystems.

Publication:

New paper published in Energy Procedia.

Congratulations Will!

William Haddick has been selected to be part of the Undergraduate Research Opportunities Program UROP Fall 2018! Great job!

Goldschmidt 2018:

Want to know more about the U-series in basalts? Lynne Elkins will talk about the good, the bad and the ugly of using U-series disequilibria as tracers for mantle lithological heterogeneities. Friday August 17, Session 4i.

New team member:

William Haddick, senior undergrad in the Geology and Geophysics department, will join me this fall for a senior thesis on magma-rock interaction and oceanic crust accretion.

Workshop for Early Career Geoscience Faculty

22-26 July 2018: I will be attending the workshop "Early Career Geoscience Faculty: Teaching, Research, and Managing Your Career" at University of Maryland, College Park, MD

Arrived at the U.

I’m thrilled to annonce that I just joined the Department of Geology and Geophysics at the University of Utah as an Assistant Professor in Igneous Processes.

Visit to Vrije Universiteit Amsterdam:

In summer and fall 2017, I worked at V.U. Amsterdam with Janne Koornneef to perform high spatial resolution isotopic analyses on lower crust cumulate rocks.

CUROP Project:

During summer 2017, Matthew Cook performed element maps on oceanic cumulate rocks to characterise the compositional diversity of the oceanic rock for his CUROP project. He successfully presented his work last month.

Goldschmidt 2017:

Invited talk in the session 05a: "MORB Petrogenesis: From Mantle Partial Melting to Fractional Crystallization"

Publication:

New paper published in Geochemical Perspectives Letters.

Funding:

Second year of funding for my NSF project has been approved!

Visit to IODP Core repository:

MARUM Bremen, May 14th to 19th: collecting samples from the Atlantis Massif (IODP 304/305)

GGRiP Meeting:

Bristol, April 3rd and 4th, GGRiP Meeting 2017

Seminar:

University of Utah, Salt Lake City, USA - February 23rd, 2017

Women in volcanology:

Our message for girls

Seminar:

CRPG, Nancy, France - February 6th, 2017

Prifysgol Caerdydd:

I'm excited to announce that I just started (January 2017) a new position as a COFUND fellow in the School of Earth and Ocean Sciences at Cardiff University. I will use a combination of experimental and analytical techniques to reconstruct the evolution of the oceanic crust.

Highlight & Spotlight:

My latest article featured in the Editors' Highlight of Journal of Geophysical Research - Solid Earth. And also in the Research Spolight of EOS.

Seminar:

Sept. 19th, 2016: Invited research presentation at the Department of Geological Sciences and Engineering, University Of Nevada, Reno

Funding:

I just got confirmation from NSF: My project on the effect of the melting regime for quantifying the mantle heterogeneities has been funded!

Publication:

New paper accepted in Journal of Geophysical Research - Solid Earth
Information on how to use Melt-PX can be found here


Fluid flow in porous media

Flow and transport in porous media have many applications in geoscience and energy science. Examples include magma migration through the Earth’s mantle and crust, CO2 storage in geological sub-surface formations, secondary oil migration, planetary differentiation. High-temperature experiments have a unique advantage that they can be quenched and the experimental products can be characterized with high-resolution imaging (microtomography and SEM) and analytical (microprobe, LA-ICP-MS) techniques.
One aspect of this project, funded by NSF, is to simulate the migration of magmas through the mantle and better quantify the impact of their migration on the chemical and physical characteristics of magmas. The second aspect of this project, funded by an ASC DNI grant, will be to characterize the 3D fluid distribution at the pore-scale of two immiscible fluids in porous media.


Mantle2MORB

MORB, having formed by mantle melting, retain many characteristics of their mantle source. Hence, MORB has traditionally been the primary tool to map geochemical variations and melting processes of the upper mantle. However, although the mantle has long been established to be compositionally heterogeneous, MORB display relatively homogeneous compositions. This has been suggested to be the result of magma mixing during their travel from the mantle source to the surface. Oceanic cumulates are believed to be the first crystallization products of MORB once they enter the crust. Hence, they record the full compositional range of melt compositions delivered to the crust. The high spatial resolution isotopic analyses of the primitive cumulate minerals reveal that a significant part of the mantle heterogeneity is hidden in MORB with a factor seven between the heterogeneity record in cumulate minerals and the heterogeneity observed in the MORB. The results of this study are published in Nature geoscience. Furthermore, the compositions of the cumulates record the crustal evolution of MORB, and hence offer the opportunity to reconstruct the processes that control the MORB trace element evolution.


Melting regime and mantle heterogeneity

Thanks to numerous experimental studies, parameterizations are available to model the melting behavior of peridotite and pyroxenite compositions that are thought to be present in the mantle. Based on these parameterizations, numerous studies have attempted to estimate the proportion of pyroxenites in magmatic sources. However, while these parameterizations are mostly based on batch melting experiments, oceanic basalts are likely to be formed by near fractional melting rather than batch melting. My preliminary calculations show that using a batch melting regime instead of a continuous regime might yield to a significant underestimation of the amount of recycled material in the mantle. A higher proportion of the recylcled material in the mantle has important geodynamical implications in terms of mantle composition and temperature. I'm conducting incremental melting experiments to simulate a continuous melting regime of pyroxenite. Because melt extraction during generation of MORB and OIB is likely to occur via continuous melting rather than batch melting, these new calibrations will allow me to better quantify the proportion of recycled material in the mantle source of the most abundant magmas on Earth.
I recently been funded by NSF to pursue this project and I have been invited to present preliminary results at the Goldschmidt conference 2017 - session 5a, in Paris.


Parameterization of melting for mantle pyroxenites

A variety of data requires that the mantle source for basaltic magmatism is heterogeneous. Models of the melting of such mixtures require knowledge of the relationships between melt fraction, temperature, pressure, and bulk composition for both peridotites and pyroxenites. While various parameterizations are available to model the melting behavior of peridotites, none yet exist to model pyroxenite melting.
I used experimental data from the literature to build an empiric model, Melt-PX, that, while remaining mathematically simple, succeeds in capturing the important features of the behavior of pyroxenites melting. Coupled with a parameterization on peridotite [1], my work permits calculations of how multilithologic mantle sources melt during adiabatic decompression, including the effects of varying the composition and the modal proportion of pyroxenite in such source regions. One major result of this study has been to show that a significant portion of mantle pyroxenites can start to melt after the peridotite along an adiabatic path.
The final model: Melt-PX, is published in Journal of Geophysical Research - Solid Earth, and can be downloaded here. This study has been featured in AGU Editor's Highlights in EOS Research Spotlight.
A previous version of the model has also been used by Shorttle et al. (2014) to determine the proportion of recycled basalt in the magma source of Iceland. The exact nature of the mantle heterogeneity beneath Iceland is discussed in a paper published in Geochemical Perspectives Letters.

[1] Katz et al. (2003), G3 4(9)


Reactive cracking investigation

The observation that anthropogenic CO2 can influence global warming has focused attention on carbon capture and storage. One proposed option for carbon sequestration is to increase the natural process that consists in the conversion of CO2 gas to stable, solid carbonate minerals in peridotites that have been tectonically exposed. Kelemen and coworker propose that peridotites may be able to capture and store billions of tons of CO2 per year and have initiated the Oman Drilling Project. This could make a significant difference in the overall CO2 budget of the planet until alternative energy sources replace global fossil fuel use. But this option needs the development of new engineered methods emulating the natural process (reactive cracking) to create dense fracture networks. More information about ongoing research on “in situ” carbon mineralization in ultramafic rocks can be found here.
We performed experiments to understand the effect of the confining pressure on the pressure of crystallization and on the reactive-cracking processes. We show that reactive cracking can occur at depths > 1km, i.e depths relevant for in situ carbon storage and geothermal energy. This study is now published in Geochemistry, Geophysics, Geosystems.


Tracer of mantle heterogeneity

Several aspects of MORB compositions, including variations in abundance of highly incompatible elements and in radiogenic-isotope ratio cannot easily be explained with a homogeneous source. In order to understand the role of these lithologies for MORB petrogenesis, experiments are necessary. Nevertheless, there are few studies on this rock-type at pressures shallower than 2 GPa and no work was devoted to the influence of this rocks-type in the major element composition of MORB.
My PhD work was devoted to experimental determination partial melting behavior of three natural pyroxenites between 1 and 2.5 GPa. To analyze the composition of liquids in equilibrium with mineral phases, I used the "microdike" technique developed by Didier Laporte, which consists of extracting small volumes of liquid into fractures of the graphite container that formed during experiments.
For the range of temperatures beneath mid-ocean ridge, compositions of melts from most of pyroxenites are close melt from peridotite. On the contrary, liquids from peridotite and pyroxenites would have contrasted isotopic and trace element signatures. This could explain why MORBs are rather homogeneous in terms of major elements but heterogeneous in terms of isotope and trace elements.
Otherwise, some pyroxenites yield melts with a distinct signature, such as a low-SiO2 content and/or a high FeO content, two features usually ascribed to a high average pressure of melting. Thus, MORB with high FeO and low SiO2 contents may reflect the participation of a pyroxenite component in their source rather than a higher pressure of melting.
Hence the classical criteria used to select primitive mantle-derived magmas (e.g., MORB glasses with Mg# ≥67) or to track down enriched mantle sources (MORB glasses with high incompatible element contents) must be considered with caution, otherwise melts carrying a pyroxenite signature may be eliminated.
This work has been published in 2009 in Earth and Planetary Sciences Letter. I also presented these results during the American Geophysical Union in December 2008. I have been also invited by Lithos to write a review article on the role of pyroxenites in the major-element compositions of oceanic basalts.


Interaction between pyroxenitic melt and peridotite

Interactions between pyroxenites and/or pyroxenite-derived melts and the surrounding peridotites might have a significant role on melt extraction dynamics and, ultimately, on the preservation of a pyroxenite signature in aggregated melts erupted at the Earth's surface. Here, we try to evaluate the fate of melts from pyroxenitic sources during their transport through the peridotite mantle as functions of their composition, P-T conditions and the physical state (subsolidus vs. partially molten) of surrounding mantle. In order to model these interactions, we use a simplified model of interaction, where peridotite is impregnated by a finite amount of pyroxenite-derived liquid modelled with pMELTS. Concurrently, we perform impregnation experiments in a piston-cylinder apparatus to test the validity of the calculations.
Results show that Cpx is systematically produced whereas the Ol and Opx behaviors depend on incoming melt silica activity: if it is lower than the silica activity of a melt saturated in Ol and Opx at the same pressure P and temperatureT,Opx is dissolved and Ol precipitates, and conversely. This has strong implications on the ability of pyroxenite-derived melts to migrate through the mantle. Indeed, Opx dissolution and Ol precipitation facilitates the transport of melt in the system by increasing the porosity and permeability of mantle rocks. Inversely, Opx crystallisation at the expense of Ol may slow down or even stop magma ascent by porous flow. Moreover, the ability of melts to migrate also depends on the melting degree of surrounding peridotite: the reaction with a subsolidus mantle results in a strong melt consumption resulting to a drastic decrease of the system permeability. On the contrary, melt migration to the surface should be possible if the surrounding mantle is partially melted. We illustrate these results in a model for MORB genesis taking into account the implications of melt-peridotite interactions for melt transport and mantle lithological diversity, and the role of pyroxenites for magma genesis at MORs.
This work has been published in 2012 in Journal of Petrology.


Magma focusing

The transport of basaltic melts beneath oceanic spreading centers occurs predominantly in high porosity dunitic channels, resulting from the complete dissolution of pyroxenes in peridotites mantle [1].
The formation of dunitic assemblages is due to magma focusing that is, to the circulation of important melt volumes in these channels. Many experiments were run in a piston-cylinder apparatus to simulate magma focusing processes beneath oceanic spreading centers, and to study the reaction between peridotites and basalt, as function of pressure and magma/rock ratio. Then, results were compared with pMELTS predictions.
We proposed a primitive MORBs formation model, implying: 1) partial melting of lherzolitic mantle at depth, 2) magma focusing involving the formation of dunitic channels and liquids evolution toward primitive MORBs composition by interaction with surrounding dunites, 3) destabilization of high-porosity channels to form dykes is possible at high degrees of melting. Thus, our study confirmed the necessity of dunites formation beneath the oceanic ridges and strengthens the hypothesis that high-porosity channels constitute the main mean of magma transport at oceanic spreading centers.
This work is the basis of my research project. It is focused on the genesis of oceanic basalts and combines the experimental data with numerical modeling. It has been published in 2009 in Contributions to Mineralogy and Petrology. I also presented these results during the European Geophysical Union in April 2007.

[1] Kelemen et al. (1995), Nature 375:747-753


Compositional variability of Mauna Kea shield lavas

It has been recently shown that the compositional diversity of lavas collected during the second phase of the drilling project (HDSP-2) varies with depth and that samples from the deepest part of the core have the highest variability [1].
In 2013 I supervised Valérie Payré, a first year graduate student from the ENS (École Normale Supérieure, Paris - France) to work on samples collected in this deepest part (3098-3506 mbsl) recovered during Phase-2 (2003-2007) of the HSDP-2 project [2] in order to better constrain the origin of the compositional variability of these lavas.
She conducted the petrographic and geochemical study of glasses using an electron microprobe and thermodynamic modeling using MELTS software [3] in order to determine the conditions of formation of these lavas (pressure of fractionation, water content, oxygen fugacity). All degassed samples follow a fractionation trend at 5-10 bars. Most of the undegassed (and partially degassed high-SiO2) glasses can be reproduced by simultaneous depressurization and cooling (i.e. from 70 to 25 bars – ΔT = 20°C).
Surprisingly, the results also reveal the presence of degassed samples in deep part of the drill. The preferred model to explain this observation is mixing of a relatively volatile-rich, undegassed component with magmas that experienced low pressure degassing (in the conduit or at shallow depth) during which substantial volatile amounts were lost, as previously suggested by Dixon et al. [3]. To confirm this assumption, water and carbon dioxide analyzes have to be performed on these samples.

[1] Rhodes et al. (2012), G3 13(3); [2] Stolper et al. (2009), Scientific Drilling 7:4-14; [3] Ghiorso & Sack (1995), CMP 119:197-212; Dixon et al. (1991)


 
 
 

Dr Sarah Lambart
Geology and Geophysics, Frederick Albert Sutton Building
115 S 1460 E, Room 409
Salt Lake City, UT 84112-0102