Postdoctoral Researchers

Dr. Gavin Piccione (https://gavinpiccione.github.io/) – Postdoctoral Research Associate, 2023-Present

B.S. Geosciences (Summa cum Laude), Stony Brook University, 2016; Ph.D. Earth & Planetary Sciences, University of California Santa Cruz, 2023;

I am a geochemist and geochronologist with broad interests in the processes that link Earth’s climate and hydrosphere through time. My research leverages both traditional and novel terrestrial sedimentary archives to create time-resolved datasets that describe paleoclimate evolution on decadal to million-year timescales. I have applied these methods to reconstruct the rates of Antarctic ice sheet growth and retreat, and the impact of glaciers on global geochemical cycles. While at Brown, I am working with Dr. Daniel Ibarra on projects investigating the temporal variability of hydroclimate in the western US, as well as weathering beneath ice sheets. Before arriving at Brown, I earned my bachelor’s degree (with Honors) in Geoscience at Stony Brook University, and my PhD in Earth and Planetary Science at the University of California Santa Cruz.

Research Associate/Lab Manager

Hannah Tompkins – Research Associate, 2024-Present

B.S. Geological Sciences, University of Rochester, 2019; M.S. Geosciences, University of Arizona, 2022

Hannah is an isotope geochemist and detail-oriented laboratory manager with a deep appreciation for the meticulous nature of clean lab wet chemistry. At Brown, she has been working in the Trace Metal Laboratory (TML), where she sets up Li isotopes, Sr isotopes, and U-series/U-Th geochronology systems, contributing to a diverse range of projects in the Ibarra group. Her master’s research focused on constraining magmatic equilibrium Zr isotope fractionation in zircon growth experiments. Outside of the lab, you can find her trying a new dance class with her cousin, immersed in a science fiction novel, or walking and eating her way around Providence.

Graduate Students

Catherine (Cathy) A. Gagnon (IBES Profile; LinkedIn) – DEEPS Ph.D. Candidate – Department of Energy Office of Science Graduate Student Research (SCGSR) program recipient

B.S. Geoscience (w/ hydrogeology concentration), The Pennsylvania State University, 2020

Cathy is a PhD candidate at Brown University excited about stable isotope geochemistry, terrestrial paleoclimatology, and volcano-sedimentary lithium deposits. Broadly speaking, she uses a variety of stable isotope and mineral characterization methods to understand the geological, environmental, and thermodynamic mechanisms controlling lithium enrichment in sedimentary rocks. Her geological field training involved mapping landscapes in Montana, Wyoming, Utah, and Idaho. Current research interests have since taken her to the arid and semi-arid basins of California, Nevada, and the Atacama desert in Chile. She has conducted research as an intern for Lithium Americas and will be conducting research at the Berkley National Lab this Fall/Winter as part of the DOE SCGSR program. In addition to research, Cathy loves winter hiking, rollerblading, and playing ice hockey around the greater Boston area where she is from. She resides in Norton, MA with her fiancé, little black cat, and kind and goofy dog, Penny.

Sebastian (Seb) Muñoz (IBES Profile) – DEEPS Ph.D. Candidate – Brown Presidential Fellow & National Science Foundation Graduate Research Fellow – co-advised by Larry Smith

B.S. Geological Sciences (hydrogeology honors) and B.A. Liberal Arts, University of Texas, Austin, 2018

Sebastian spends all of his time thinking about, studying, or boating on rivers. He is interested in how surface water chemistry will change in response to human activities and climate change. Previous work includes studying rock glaciers contributions to river flows in northern Chile, and understanding surface water and groundwater interactions downstream of a dam in the Colorado River near Austin, TX.

M. Justin Custado (IBES Profile) – DEEPS Graduate Student

B.S. Chemistry, University of the Philippines – Diliman, 2015 & M.S. Environmental Science, University of the Philippines – Diliman, 2021

Riley Havel  (IBES Profile) – DEEPS Graduate Student  – National Science Foundation Graduate Research Fellow

Mónica Geraldes Vega – DEEPS Graduate Student – co-advised by Kim Cobb

B.A. Geological Sciences, Mount Holyoke College, 2022

Mónica is broadly interested in paleoclimate, biogeochemistry, and geochronology. At Brown, she’s working on understanding abrupt climate change in the tropics using stalagmite records from the Philippines during the late Pleistocene. She is also interested in understanding karst geochemical processes and the relationship between surface and subsurface hydrology. Driven by questions related to tropical paleoclimate and general excitement about learning and sharing knowledge, Mónica is also enjoying her transition from her native Dominican Republic to Providence life, where she is getting better at cooking every day.

Undergraduates

Sarah Levine, Undeclared (Geology-Chemistry or Chemistry), Brown University, 2027

Fall 2024 SPRINT | UTRA Award

Sarah is a second-year undergraduate student interested in environmental chemistry. She is fascinated by how complex systems of chemical reactions are affected by human activity. She works with Sebastian to study how deglaciation changes weathering processes. Outside of that she enjoys traditional Korean drumming, hiking, gardening, and disability justice activism.

Eleanor Barth Wu, A.B. Candidate, Geology-Chemistry, Brown University, 2026

I am a third year undergraduate studying geochemistry. Currently, I am working with Sebastian and Hannah to elucidate glacial weathering processes in Alaska. Having been a member of Brown’s inaugural soil-judging team, I am also excited by the relationship between weathering and soils. In my free time I write a restaurant review column for the Brown Daily Herald, and I enjoy biking around Rhode Island.

Josephine Harrison, Undeclared, Brown University, 2028

Kira Ivanova, Undeclared, Brown University, 2028

Summer 2025 SPRINT | UTRA Award

Jenna Serotta, Sc.B. Candidate Earth, Climate, and Biology; Certificate of Intercultural Competence for German

Summer 2025 SPRINT | UTRA Award

Jenna joined the Ibarra Lab in the summer of 2025, collaborating with Justin and Hannah to investigate silicate weathering processes in Southeast Asia using strontium isotope data. She especially enjoyed working in the Trace Metals Lab, appreciating its meticulously maintained sterile environment and consistent temperature of 64°F. Among her favorite responsibilities in the TML were rinsing equipment with Milli-Q water and overseeing a five-day beaker-cleaning protocol involving strong acids and aqua regia.

Beyond the laboratory, Jenna is an accomplished scholar of the German language, having earned several accolades for her expertise. She is also passionate about vocal performance, serving as the music director of The Alef Beats, a Jewish-themed a cappella group. In addition, she sings as an alto with the Brown University Chorus and enjoys both heavy weightlifting and Zumba in her free time.

Claire Xu, Sc.B. Candidate in Earth, Climate, and Biology; Certificate in Data Fluency

Fall 2024 SPRINT | UTRA Award

2025 CES-WAVE Fellow, Caltech

Claire is a third-year undergraduate student studying Geobiology and Data Science. Her research interests lie at the intersection of Earth science and biology, particularly hydrology, ecology, and coastal oceanography. She is currently working with Justin to understand how El Niño-Southern Oscillation (ENSO) events affect triple oxygen isotope signatures and examine Δ’17O as a new geochemical proxy. Claire is also passionate about scientific illustration, having contributed to SciComm projects such as the 2024 DEEPS Summer Research Highlights, which she wrote and illustrated. Outside of the lab, she enjoys engaging with the DEEPS community as a GeoDUG board member, drawing, painting, and exploring National Parks.

Sarah Kramer, Undeclared, Brown University, 2028

Fall 2025 SPRINT | UTRA Award

Sarah is a second-year undergraduate studying geochemistry at Brown University. She is interested in the interactions between biogeochemical cycles and isotope geochemistry. She is working with Monica, Gavin, and Owen to study the Philippines speleothems, karst cave geography, and what these formations tell geologists about past surface environments. In her free time, Sarah loves to play music with her friends and going on walks around Providence.

Former Group Members

Postdocs

Dr. Natasha Sekhon (IBES Profile) – Voss Postdoctoral Research Associate and Presidential Diversity Postdoctoral Fellow, 2021 to 2023

Current: Assistant Professor at Occidental College

Dr. Kristina Butler – NSF EAR Postdoctoral Fellow, 2023

Current: Assistant Professor at UT Dallas

Dr. Evan Ramos – NSF EAR Postdoctoral Fellow, 2021 to 2023; Affiliated Postdoc 2023-2024 (Primarily at Rice University)

Current: Assistant Professor at University of Pittsburgh

Dr. Devon Kerins (IBES Profile) – Voss Postdoctoral Research Associate, 2024; Visiting Scholar, 2025

Current: Assistant Professor at University College Dublin

Graduate Students

Jiquan Chen – Ph.D. Candidate at China University of Geosciences, Beijing (2022-Present) & Visiting Ph.D. Student at Brown University (2023-2024)

Theodore (Ted) Bobik – Sc.M. Earth, Environmental & Planetary Sciences, Brown University, 2024

Thesis: Filling in the Gaps: Paleosols as Regional Recorders of Hydroclimatic Change in Northeast China at the Cretaceous – Paleogene

Undergraduates

Celia Kong-Johnson, A.B. with Honors, Geology-Chemistry and Applied Math, Brown University, 2025

Fall 2023 SPRINT | UTRA Award

2023 RSI-WAVE Fellows, Caltech

2024 Sarah LaMendola Undergraduate Research Award

2024 NSF SOARS Protégé at NSF NCAR, Boulder CO

2025 Senior Award for Excellence in Research, Academics, and Service

Received a National Science Foundation Graduate Research Fellowship

Senior Thesis: Phasing of Seasonal Monsoon Systems in Southeast Asia during the Late Holocene using Two Philippines Speleothems

Anna Dubey, Sc.B. with Honors, Ecology, Evolution, & Organismal Biology, Brown University, 2025

Jesse Miller, A.B. with Honors, Geological Sciences, Brown University, 2023

Summer 2022 SPRINT | UTRA Award and Research at Brown Grant

2023 GSA NE-SE Regional Meeting Presentation: Temperature Dependent Dissolution Experiments of Basalt, Dacite and Pumice from The Little Deschutes River Valley

Senior thesis: Temperature dependent dissolution experiments of basaltic andesite, dacite and pumice from the Little Deschutes River Valley, Oregon

Remote Lab Technician 2023-2024. Current: Farm Manager, The Opportunity Hub

Alejandra (Ale) Torres, B.S. Candidate Earth Science and Data Science, Southern Methodist University 2026

Summer 2024 Leadership Alliance/DEEPS REU

Tee Gotsch, A.B. Candidate Geology-Biology and Music, Brown University, 2026

Summer 2024 SPRINT | UTRA Award

Jonah Bernstein-Schalet, Sc.B. Candidate Geology-Biology, Brown University, 2024.

2023-24 Voss Undergraduate Fellowship Award

AGU 2023 Fall Meeting Presentation: Linking Post-Wildfire Soil Geochemistry to Carbon Processes and Chemical Weathering

GSA NE 2024 Presentation: Wildfire impacts on soil chemistry and the role of pyrogenic carbon in soil mineral transformation

Senior Thesis: Linking Stream Chemistry to Soil Biogeochemistry to Investigate the Environmental Legacy of Wildfire in Oregon’s West Cascades

Current: Research Scientist, Mati Carbon

Whitney Vieira Ribeiro, Sc.B. Geology-Biology, Brown University, 2024.

Senior thesis: Tracking the Impact of the K/Pg on Pelagic Shark Diversity Using Dermal Denticles

Current: Paleontological Research Institution

Marina Benson, Sc.B. with Honors, Geology-Biology and B.A. Music, Brown, 2024

2023-24 Voss Undergraduate Research Fellow

Senior thesis: Edgartown Great Pond is Turning Green! The Ecological Impacts of Nitrogen Pollution on Coastal Estuaries

Daniel Graves, Sc.B. with Honors, Environmental Sciences, Brown University, 2024

GSA NE Presentation: Variability of groundwater recharge in variable climates: a groundwater flow model for the Southern Great Basin

Senior thesis: Variability of groundwater recharge in variable climates: a water-energy balance groundwater model for the arid Southern Great Basin

Shaw Miller, Sc.B. with Honors, Geology-Biology, Brown University, 2023.5