About

Magdalena Osburn is an Associate Professor of Earth and Planetary Sciences and (by courtesy) Civil and Environmental Engineering at Northwestern University. She holds a Ph.D. and M.S. in Geobiology from the California Institute of Technology, and a B.A. summa cum laude in Earth & Planetary Sciences and Environmental Studies from Washington University in St. Louis. Her research focuses on how biological molecules, particularly lipids, record information about their formation environment and the organisms that produce them. She uses these molecules to study both modern and ancient microbial habits, leveraging their preservation in sediments and rocks to archive environmental data over long timescales. Her work applies tools from organic geochemistry, microbiology, and stratigraphy to investigate microbial and biogeochemical cycling in various environments. A significant part of her research involves understanding the isotopic signals, especially hydrogen isotopic composition, in lipids to interpret environmental water and microbial metabolism. Her research also includes geochemical modeling of aqueous environments, the chemical evolution of the ocean-atmosphere system during isotope excursions, and carbonate sedimentology with an emphasis on microbialite preservation and morphology.

Research topics

• Biology
• Ecology
• Paleontology
• Environmental science
• Geology
• Earth science
• Oceanography
• Physical geography
• Botany
• Zoology
• Microbiology
• Aeronautics
• Geography
• Astrobiology
• Aerospace engineering
• Engineering
• Engineering ethics

Selected publications

• High permeability, meteoric influx, and biomass promote microbial signatures in upper km of sedimentary basins

  2026-02-12

  article

  The few studies of modern or ancient microbial communities beyond ~100 m depth in the crust limit our view into the complex deep terrestrial biosphere. In sedimentary systems, isotopic signatures of by-products of anaerobic microbial activity, such as microbial methane and carbon dioxide, and molecular signatures of oil biodegradation are more widespread. Yet, it’s unclear how these biosignatures in subsurface fluids relate to microbial biomass and their hydrogeologic context. We expect that hydrological parameters, such as meteoric influx, permeability, porosity and pore throat size, as well as the burial and thermal history of sedimentary environments, are key to microbial habitability. Here, we compiled molecular and isotopic datasets of CO2 and CH4 with oil density (API gravity), microbial cell counts, and stable water isotopes of formation waters for sedimentary basins across the United States and Canada to investigate the depth and spatial distribution of biosignatures in produced fluids related to cell abundance, hydrologic properties, and burial/thermal histories. Most robust signatures of microbial activity in CO2, CH4, and oil occur in the upper ~1km of sedimentary basins, co-occurring with relatively high biomass (>104 cells/mL), permeability (>10-16 m2), and meteoric circulation. Our results provide insights into the distribution as well as geologic and hydrologic controls on microbial activity in the terrestrial sedimentary deep biosphere which may have been imprinted in the rock record. The identified regions with more robust biosignatures may warrant more comprehensive fluid, rock and microbial studies to investigate these potential unique extant ecosystems.

  PublisherDOI

• Subsurface Life on Earth as a Key to Unlock Extraterrestrial Mysteries

  Microbial Biotechnology · 2025-12-01 · 2 citations

  articleOpen access

  The first forms of life on Earth were microbial, preceding the evolution of multicellular life by more than two billion years. Based on our current understanding of the origin of life, it is likely that the first life forms on any extraterrestrial world would also be microbial. Due to the extreme temperatures, radiation or aridity on most planetary surfaces, such extraterrestrial microbes would most likely dwell in subsurface environments. Earth's subsurface features a wide range of environments, including deep marine sediments, crustal aquifers, rock fracture fluids, hydrocarbon reservoirs, caves and permafrost soils. These environments are known to host an immense diversity of life forms, predominantly microbes that survive or even thrive under extreme conditions and energy scarcity. Life's ability to endure and possibly evolve in Earth's subsurface lends credence to the possible existence of life beyond our planet and provides a blueprint for the extraterrestrial life forms and biosignatures we might expect. The exploration of space via extraterrestrial samples analysed on Earth, in situ extraterrestrial analyses, and remote sensing continue to advance our search for and understanding of potential biosignatures on other planetary bodies. But by investigating Earth's deep, dark and isolated ecosystems, we not only broaden our understanding of life's adaptability but also refine our strategies and technologies for detecting life on other planets and moons. Subsurface exploration is not just a frontier of Earth science-it is a cornerstone of astrobiology and in the pursuit of understanding the multitude of processes that could create and sustain life anywhere. In this opinion article, we discuss the latest highlights in subsurface research and technology, how Earth's subsurface environments serve as models for potential environments on other planetary bodies, why insights into subsurface microbiomes inform the search for life elsewhere, and which technologies and developments will advance the field in the future.

  PublisherOA PDFDOI

• Subsurface microbiology and the pressing societal need to support future exploration

  FEMS Microbiology Ecology · 2025-12-05

  articleOpen access

  Subsurface microbiology is at a crossroads, evolving from asking 'who's home' to seeking clarity on microbes' functionality and the key processes that constrain subsurface life. Importantly, the processes subsurface microorganisms mediate are central to societal needs to mitigate climate change and address waste storage, as proposed solutions to both involve subsurface habitats. However, subsurface sampling opportunities and funding remain limited and, in some cases, have diminished. This perspective article is aimed at scientists who have or might develop an interest in the geomicrobiology of the subsurface, for funding agencies worldwide, and for scientists and engineers engaged in the extractive and waste disposal industries. It briefly reviews subsurface science's history and current status and proposes some actions for moving forward. In particular, we see the continued need for engaging early-career microbiologists in drilling projects, increasing access through industry partnerships, microbiology-led drilling projects, and creating interdisciplinary drilling projects by including microbiologists during the drilling project planning.

  PublisherOA PDFDOI

• Living in the subsurface: local adaptations that define a global biome

  2025-01-01

  article1st authorCorresponding
  PublisherDOI

• Origins and Alteration of Ediacaran Carbonates Recording the Shuram Excursion in Oman

  Geochemistry Geophysics Geosystems · 2025-05-01 · 8 citations

  articleOpen access

  Abstract The Shuram excursion is the largest known negative carbon isotope excursion in Earth's history. Recognized globally, it follows the Ediacaran Gaskiers glaciation and precedes a marked increase in the diversity and complexity of the earliest macroscopic multicellular organisms in the fossil record. A key question is whether this excursion reflects a primary perturbation to the carbon cycle, which would provide crucial insights into the environmental conditions shaping the earliest animals, or whether it is largely an artifact of later diagenetic alteration. To evaluate the extent of diagenesis in these rocks and constrain how much of the excursion reflects a primary signal, we investigate the sedimentology and geochemistry of carbonate strata in Oman using a variety of techniques spanning multiple spatial and temporal scales. Our multi‐faceted analysis identifies and characterizes four modes of diagenetic alteration, with sediment‐buffered conditions and authigenic carbonate precipitation as the dominant processes. However, the degree of alteration is insufficient to account for the range of marine sedimentologic and geochemical trends across the carbon isotope excursion. This suggests that, even with evidence of diagenesis, the rocks preserve a measurable record of changing conditions in both terrestrial and marine environments, offering unique insights into Earth's systems during a pivotal time in early animal evolution.

  PublisherOA PDFDOI

• The impact of CO2-charged fluids on the aqueous geochemistry of terrestrial aquifers

  Geochimica et Cosmochimica Acta · 2025-08-08

  articleOpen access

  Understanding the formation and evolution of subsurface CO 2 -rich terrestrial fluids and reservoirs is key for modelling the storage of CO 2 in the crust, fracture-controlled fluid flow, and/or diffusive transport of fluids from deep crustal settings. However, migration and exchange mechanisms associated with CO 2 -rich environments remain poorly constrained. In at least one natural CO 2 -rich setting, a Precambrian crystalline brine component has been postulated based on δ 18 O and δ 2 H signatures which plot above the Global Meteoric Water Line. In this study we evaluate the intriguing potential role of migration and mixing of deep fluids in the shallow subsurface using a novel geochemical and microbiological framework approach which incorporates noble gas, stable isotope, and microbial diversity-based approaches. Through targeting a series of 10 springs which sample depths of up to 250 m at Saratoga Springs, NY, USA, this integrated approach finds no evidence of a deep shield brine component and reveals only migration of a principally deep crustally-derived CO 2 (87.2–99.3 %) with a minor mantle component. Instead, this study reveals how putative CO 2 dissolution-enhanced water–rock interaction coupled with ≤17 % CO 2 -H 2 O 18 O isotopic exchange can produce the observed aqueous geochemical composition, including the apparent shield brine signal. Microbial community data presented here also suggest distinct assemblages between shallow, freshwater and deep, saline spring fluids in line with geochemical interpretations. Crucially, our novel integrated approach highlights how migrating CO 2 -rich phases in subsurface environments can overprint and drive geochemical reactions in the subsurface to produce aqueous geochemistries which mimic characteristics of unrelated deep fluid systems.

  PublisherDOI

• Microscale evidence of episodic fluid mixing and microbial activity in deep fracture systems of the Paradox basin, USA

  2025-01-01

  article
  PublisherDOI

• Referee report. For: Targeting deeply-sourced seeps along the Central Volcanic Zone [version 1; peer review: 1 approved, 1 approved with reservations]

  Faculty of 1000 Research Ltd · 2024-01-01

  peer-reviewOpen access1st authorCorresponding
  PublisherDOI

• Soil moisture and water redistribution patterns in white oak (Quercus alba) saplings and trees in fragmented urban woodlands

  Environmental Research · 2024-10-11

  article
  PublisherDOI

• ANCIENT TO MODERN GEOLOGIC AND HYDROLOGIC FORCINGS DRIVE DEEP BIOSPHERE ACROSS COLORADO PLATEAU

  Abstracts with programs - Geological Society of America · 2024-01-01

  article
  PublisherDOI

Recent grants

• Collaborative Research: Evolution of Subsurface Microbe-Rock-Fluid Systems

  NSF · $740k · 2021–2026

Frequent coauthors

• Jamie McFarlin

  University of Wyoming

  27 shared

• Andrew L. Masterson

  26 shared

• Yarrow Axford

  Northwestern University

  26 shared

• Lily Momper

  Northwestern University

  17 shared

• Lydia Bailey

  Planetary Science Institute

  17 shared

• J. G. Blank

  17 shared

• Bradley S. Stevenson

  Planetary Science Institute

  17 shared

• Ji‐Hyun Kim

  Korea Institute of Geoscience and Mineral Resources

  16 shared

Education

• PhD, Geobiology

  California Institute of Technology

  2013

• M.S., Geobiology

  California Institute of Technology

  2008

• BA, Earth and Planetary Sciences

  Washington University in Saint Louis

  2007