About

Sean P. S. Gulick is a Research Professor at the UT Institute for Geophysics with interests in marine geology and geophysics, plate boundaries, glacial sequences, and impact processes. His work involves understanding the dynamics of Earth's systems through the study of geological and geophysical processes, contributing to the broader understanding of Earth's structure and history.

Research topics

• Astrobiology
• Geology
• Physics
• Biology
• Computer Science
• Environmental science
• Chemistry
• Earth science
• Seismology
• Mechanics
• Paleontology
• Oceanography
• Nanotechnology
• Botany
• Astronomy
• Ecology
• Materials science

Selected publications

• Exploring the origins of magnetization within the Chicxulub crater upper peak ring

  Meteoritics and Planetary Science · 2025-02-28 · 2 citations

  articleOpen access

  Abstract Large terrestrial impacts may produce vast subsurface hydrothermal systems, capable of generating conditions favorable to the origin of life. Modeling suggests that these systems may persist for >1 million years for basin‐sized craters; however, direct experimental constraints on hydrothermal system duration are needed. Paleomagnetism may be used as a tool to study the nature and duration of the postimpact hydrothermal system generated within the upper peak ring of the 200 km diameter Chicxulub crater (Yucatán Peninsula, México). Previous work observed that upper peak ring suevite samples contained characteristic remanent magnetizations with negative and positive inclinations, with most samples having a magnetic inclination close to −44°, the expected paleoinclination at the crater at the time of the impact. This magnetic record was at the time interpreted as chemical remanent magnetization (CRM) acquired over a period of at least 150 thousand years, from the time of the impact in geomagnetic Chron C29r into Chron C29n. We conducted further paleomagnetic and rock magnetic studies of upper peak ring rocks and found that, while most samples likely contain CRM acquired during Chron C29r, the dispersion of magnetic inclinations within suevite subunits is more likely attributed to pre‐depositional remanence held within clasts than the recording of magnetic reversals. Therefore, the paleomagnetic record of the peak ring suevites is non‐ideal for inferring the duration of the Chicxulub postimpact hydrothermal system.

  PublisherOA PDFDOI

• From impact to extinction to recovery: Discoveries of IODP-ICDP Expedition 364 to the Chicxulub impact structure

  Marine Geology · 2025-10-01

  articleOpen access1st authorCorresponding

  In 2016, International Ocean Discovery Program Expedition 364, with support from the International Continental Scientific Drilling Program, drilled into the peak ring of the Chicxulub impact structure, famous for its causal link to the mass extinction at the end of the Cretaceous. In this summary paper, we discuss key findings from Site M0077 on the cratering processes, marine ecosystem recovery after the mass extinction, and the post-impact hydrothermal system and habitability of the impact structure. Important results include (1) the confirmation of the dynamic collapse model of peak ring formation, (2) insights into impactite emplacement processes on Earth, where water is a key component, (3) discovery of the iridium anomaly within the impact basin, unequivocally linking the Chicxulub impact basin to the global Cretaceous-Paleogene (K-Pg) boundary layer, (4) evidence for key atmospheric inputs of dust, sulfate aerosols, and soot, all likely contributing to global cooling and reduction of photosynthesis as drivers for extinction, (5) rapid recovery of life within the ocean overlying the crater, including a primary succession driven by in part by picoplankton before a transition over 100 s kyr to diversifying planktic communities, and (6) the presence of a long-lived hydrothermal system with extant thermophilic life in the buried peak ring 66 Myr later. The Chicxulub crater represents exceptional scientific opportunity in that it bridges planetary science, impact dynamics, and astrobiology; the integration of such findings continue to reveal the transformative power of asteroid impacts as a major geologic and biologic process. • Summary of major results and next research steps from the IODP-ICDP scientific drilling expedition to the Chicxulub impact structure • Dynamic collapse model of peak ring impact basin formation validated • Crater filled with impact melt rock and melt-bearing breccia (suevite) and underwent ocean resurge • Chicxulub unequivocably linked to Cretaceous-Paleogene mass extinction containing the global iridium layer and producing dust, sulfate aerosols, and soot • Recovery of life in crater is similar to global ocean with primary succession driven by picoplankton before transitioning over 100 s of kyr to plankton dominated communities • Chicxulub subsurface contained extant thermophilic biota and evidence for long-lived hydrothermal system

  PublisherDOI

• High‐Fidelity Cretaceous‐Paleogene Boundary Investigations: Records of Impact and Transport

  Geochemistry Geophysics Geosystems · 2025-10-01

  articleOpen accessSenior authorCorresponding

  Abstract The Chicxulub impact on the Yucatán Peninsula triggered the end‐Cretaceous mass extinction 66 million years ago, but physical models still struggle to accurately describe ejecta generation and transport from this and other large meteorite impacts. To better constrain these processes, Kaskes et al. (2025), https://doi.org/10.1029/2024gc012151 completed detailed micro‐X‐ray fluorescence (μ‐XRF) mapping of a K‐Pg boundary sequence preserved at Starkville South (Raton Basin, Colorado, USA). Their results directly challenge the previous “dual layer” model of ejecta sequences exemplified in the North American K‐Pg outcrops, where one layer hosts the ballistically emplaced impact spherules and the overlying layer hosts the shocked minerals that were atmospherically transported. The new Kaskes et al. (2025), https://doi.org/10.1029/2024gc012151 model describes four distinct layers: (a) the ballistically emplaced spherules, (b) the ballistically emplaced shocked minerals, (c) an initial settling of atmospherically transported Ni‐ and Cr‐rich dust, and (d) a gradual decrease of impact‐generated dust back to background concentrations. Kaskes et al. (2025), https://doi.org/10.1029/2024gc012151 provide high‐resolution geochemical analyses offering new insights into the timing and mechanisms of ejecta production, transport and deposition after a large meteorite impact event, which the community can apply to other K‐Pg sites around the world.

  PublisherOA PDFDOI

• Sequence and cyclostratigraphic analysis of Paleocene carbonate sediments in the Chicxulub impact crater: Implications for sea level change and climate dynamics

  2025-03-14

  preprintOpen accessCorresponding

  The early Paleogene represents a greenhouse Earth experiencing large-scale global environmental changes after the Cretaceous-Paleogene extinction. Understanding climate and ocean dynamics during this recovery phase is challenging due to the scarcity of continuous, carbonate-rich sedimentary records. The Paleocene interval of International Ocean Discovery Program−International Continental Scientific Drilling Program (IODP-ICDP) Site M0077 from within the Chicxulub crater provides such an archive. Sequence and cyclostratigraphic analyses reveal condensed and rhythmic bedding, transitioning between marl or argillaceous wackestone and foraminiferal packstones. These 5−33-cm-thick cycles document low-amplitude sea-level changes or local environmental shifts in the Chicxulub basin associated with sea level. The cycles exhibit retrogradational, progradational, or aggradational facies stacking patterns, indicative of transgressive, highstand, and shelf margin systems tracts. Progradational packages align with global sea-level events, suggesting a eustatic driver. Cyclostratigraphy on the sediments’ color reflectance reveals 10 cm and 20 cm periodicities, interpreted as 41 k.y. obliquity and 100 k.y. eccentricity signatures. These climate-driven cycles resemble Paleogene hyperthermals, intensifying the hydrologic cycle and erosion of fine-grained siliciclastic sediments in the Chicxulub hinterland. Thereby, hyperthermals correspond to marl or argillaceous wackestone facies. Moreover, sequence boundaries tend to correspond to minima in the 1.2 m.y. obliquity modulation cycle. This longer-term astronomical control on sea level and climate offers insights into potential drivers of eustatic sea-level change in the Paleocene greenhouse world. The phase relationship between sea level and the 1.2 m.y. obliquity cycle indicates increased water storage in continental reservoirs during periods of astronomically suppressed seasonality (i.e., 1.2 m.y. obliquity minima). Thus, the carbonate sedimentological study of the Paleocene Chicxulub sequences provides unique insights into both local and global environmental dynamics.

  PublisherDOI

• Unlocking a Global Ocean Mixing Dataset: Toward Standardization of Seismic-Derived Ocean Mixing Rates

  Journal of Atmospheric and Oceanic Technology · 2025-05-13

  articleOpen access

  Abstract Turbulent mixing is vital for water transformation in the ocean and sustains the global thermohaline circulation. Despite decades of global observations using different platforms, our understanding of ocean turbulence is still limited. More observations are needed to better characterize the spatiotemporal distribution of mixing to reduce uncertainties in climate models. Marine seismic reflection surveys are an untapped data resource for high-resolution ocean turbulence observation. Turbulent mixing can be extracted from seismic data through horizontal internal wave slope spectra. However, to date, a standardized approach to prepare seismic data for this spectral analysis is still lacking, leading to insufficient consideration of the impact of noise on the resulting diffusivities. To address these issues, we perform a full-wavefield synthetic modeling and processing to reveal noise-induced overestimation of diffusivities. We further propose a widely applicable workflow and apply it to three field seismic surveys with increasing noise levels conducted in regions of different turbulence environments: ocean ridges, open ocean interior, and continental slope. The derived diffusivities are benchmarked against direct measurements around the region to show the fidelity of this seismic method. The extended observation records by seismic data across the Kauai Channel and away from the Mid-Atlantic Ridges reveal the importance of topography in modifying the propagation of internal tides and the distribution of turbulent mixing in both near and far fields. Our proposed workflow marks a key advancement toward standardization of seismic-derived ocean mixing rates and holds the potential to unlock massive marine seismic reflection datasets worldwide for ocean mixing characterization.

  PublisherOA PDFDOI

• Findings from Impact Crater and Associated Research United States (ICAARUS) Workshop 2025

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Multiple lines of evidence for a hypervelocity impact origin for the Silverpit Crater

  Nature Communications · 2025-09-20

  articleOpen access

  An impact origin for Silverpit Crater, on the UK continental shelf, has been contested over the last two decades, with a lack of definitive evidence - traditionally petrographic evidence of shock metamorphism - to resolve the debate. Here we present 3D seismic, petrographic and biostratigraphic data, and numerical impact simulations to test the impact hypothesis. The seismic data provide exceptional imaging of the entire structure, confirming the presence of a central uplift, annular moat, damage zone and numerous secondary craters on the contemporaneous seabed. The distribution of normal and reverse faults in the brim, and curved radial faults around the central uplift suggest a low-angle impact from the west. The pitted, flat-topped central uplift at the top chalk horizon may indicate significant devolatilization of chalk immediately following impact. Biostratigraphic data confirm that this event occurred during the middle Eocene, between 43-46 million years ago. Petrographic analysis from the reworked ejecta sequence in the nearby 43/25-1 well reveals two grains with shock lamellae, indicating shock pressures of ~10-13 GPa, consistent with results from our numerical models. This combination of data and modelling provide compelling evidence that Silverpit Crater is an exceptionally preserved hypervelocity impact structure.

  PublisherDOI

• 66 Million Years of Sustained Hydrothermal Convection at Chicxulub Crater

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Using Radar Surface Reflectance to Investigate Cryptomaria: A Comparative Study of Lunar Deposits

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Subglacial erosion rates calculated from proglacial sediments in two marine terminating glaciers in West Greenland

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

Recent grants

• Collaborative Research: Imaging and Modeling Impact Generated Deformation at the Chicxulub Crater, Joint US/UK/Mexico Investigation and IODP Site Survey

  NSF · $523k · 2003–2007

• COLLABORATIVE RESEARCH: ST. Elias Erosion/tectonics Project (STEEP)

  NSF · $769k · 2004–2011

• Exploring structural controls on great earthquake rupture and architecture of the Sumatra-Andaman convergent margin: A regional seismic reflection survey in collaboration with the

  NSF · $359k · 2007–2012

• Collaborative Research: Linking climate-driven changes in erosion to tectonic processes along the southern Alaska Margin

  NSF · $52k · 2014–2016

• Collaborative Research: The 2015 Taan Fiord landslide tsunami: An interdisciplinary study of cause & effect

  NSF · $48k · 2016–2017

Frequent coauthors

• A. Wittmann

  Arizona State University

  172 shared

• Jan Smit

  169 shared

• L. Ferrière

  165 shared

• Gail Christeson

  157 shared

• Sietze J. de Graaff

  Vrije Universiteit Brussel

  134 shared

• Thomas Déhais

  Vrije Universiteit Brussel

  134 shared

• Steven Goderis

  Vrije Universiteit Brussel

  127 shared

• Joanna Morgan

  Imperial College London

  126 shared

Education

• PhD, Earth and Environmental Sciences

  Lehigh University

  1999

• B.S., Geological Sciences

  University of North Carolina

  1993

Awards & honors

• Fellow of the Geological Society of America