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Group Members

Postdoctoral Researchers

Dr. Natasha Sekhon (Website; IBES Profile) – B.S. Earth System Sciences, University of California, Irvine, 2014; M.S. Geological Sciences, University of Texas, Austin, 2016; Ph.D. Geological Sciences, University of Texas, Austin, 2021

Natasha is a low-temperature geochemist and paleoclimatologist whose research combines concepts from karst and speleothem sciences to investigate the hydroclimate of terrestrial environments varying on seasonal to millennial time scales. She investigates the geochemical trends of stalagmites extracted from caves and actively monitors them to assess the sensitivity of climate variables on proxy systems. Her Ph.D. work explored the utility of stalagmites from near-entrance cave settings in New Mexico as potential recorders of recharge episodes. While at Brown, she will be working with the group studying the history of droughts and floods in the Philippines.


Dr. Evan Ramos – B.A. Geophysics and Planetary Sciences, Boston University, 2015; M.S. Geological Sciences, University of Texas at Austin, 2017; Ph.D. Geological Sciences, University of Texas at Austin, 2021

Evan is a geochemist whose research concerns the role of fluid-rock interactions in biogeochemical cycles, namely the carbon cycle. His M.S. research addressed fluid flow in hydrothermal environments and its influences on metamorphic decarbonation and, by extension, Phanerozoic climate. During his Ph.D., he studied the controls of silicate weathering by examining both modern and ancient surface environments with Li isotopes. At Brown and Rice University, where he is primarily appointed, he will research the coupling of the inorganic (i.e., silicate weathering) and organic carbon cycles by combining geochemical analyses of soils, river sediment, and river water with reactive transport models.


Graduate Students

Catherine (Cathy) A. Gagnon (IBES Profile; LinkedIn) – DEEPS Graduate Student – B.S. Geoscience (w/ hydrogeology concentration), The Pennsylvania State University, 2020

I came to Brown in Fall 2020 as a grad student interested in using stable isotope geochemistry methods to address questions related to past climate. My undergraduate work at Penn State involved constructing carbonate oxygen and carbon, and organic carbon isotope records of Holocene lake sediments near a Neolithic settlement in Dalmatia, Croatia. The work provided a climate context for an important time and location for the spread of early farming. My current project involves reconstructing the hydroclimate of Clayton Valley, NV from the late Pliocene to present using a combination of isotope measurements and lake balance modeling techniques. Through my work, I hope to improve future climate change projections for the western United States. In addition to research, I’m involved in k-12 earth science outreach through DEEPS STEP/DEEPS CORES. I currently reside in Providence with my little black cat.


Sebastian Muñoz – DEEPS Graduate Student – 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.



Elizabeth (Lizzy) Gaviria (LinkedIn) – DEEPS Leadership Alliance REU, Summer 2021 – B.S. Candidate Environmental Science, Rice University, 2022

I am a senior at Rice University studying Environmental Science and Energy and Water Sustainability. For the summer of 2021, I participated in Brown’s DEEPS Leadership Alliance REU virtually from Nashville, TN. My project investigates modern precipitation pathways in the western United States using archived meteorological data from the past 30+ years. With this work, I hope to uncover how these trajectories change seasonally and with short-term climate variability, such as El Niño Southern Oscillation events, in addition to providing a base for understanding the composition of water sources for my research sites.


Annabelle Gao, B.S. Candidate Geology-Chemistry, Brown University, 2023

I am a third-year undergraduate studying geochemistry at Brown University. My research interests include geochemical and isotopic applications on solar system processes as well as on Earth.  I work primarily with Catherine on learning more about the previous hydroclimate of Clayton Valley and the implications this has on the future of the region, and working with Natasha on speleothem records from the Philippines. My work revolves around taking isotopic measurements of carbonates from the field. Outside of research, I enjoy going on jogs and hikes, caring for plants, and exploring Providence.

Jesse Miller, B.A. Candidate, Geological Sciences, Brown University, 2023

As a third-year Brown University undergraduate concentrating in geology, I am excited about researching the carbon cycle and the role that silicate rock weathering and soil development play in carbon storage and the stabilization of climate. I am currently working on a modelling project with Dan and Sebastian to further our understanding of the role that poorly crystalline minerals play in carbon storage in soils and better characterize the relationship between PCMs, organic carbon, and silicate rock weathering at the river scale.


Knuckles and Gigi