E. Troy Rasbury
· Professor Sedimentary and Isotope GeochemistryVerifiedStony Brook University · Geosciences
Active 1992–2026
About
E. Troy Rasbury is a Professor in the Department of Geosciences at Stony Brook University. He holds a B.S. from Midwestern State University, an M.S. from Tulane University, and a Ph.D. from SUNY Stony Brook. His research focuses on exploring fundamental problems in geology related to time resolution and Earth's history as recorded in sedimentary archives. A major aspect of his work involves directly dating sedimentary carbonates using U-Pb methods, which includes studying the environmental conditions of carbonate formation and understanding U speciation in depositional environments. He employs techniques such as trace element mapping, fission track mapping, autoradiography, and laser ablation ICPMS to improve sample selection and dating accuracy. Rasbury has contributed to innovations in laser ablation ICPMS dating, including the development of widely used reference materials. His research extends to applying boron isotopes to study rocks, soils, waters, and plants, collaborating on projects that investigate mantle sources, groundwater nitrate tracing, ocean chemistry changes through fossil analysis, and plant uptake mechanisms. His work has resulted in numerous publications across geoscience disciplines, emphasizing his expertise in isotope geochemistry, sedimentary geology, and geochronology.
Research topics
- Geology
- Chemistry
- Geochemistry
- Paleontology
- Oceanography
- Ecology
- Environmental chemistry
- Mineralogy
- Biology
- Climatology
- Environmental science
- Botany
- Geomorphology
- Biochemistry
- Seismology
- Earth science
Selected publications
Nature Communications · 2026-05-02
articleOpen accessThe subduction organic carbon (OC) flux is closely linked with seafloor sedimentation processes. In hadal trenches, sediment transport and resuspension caused by turbidity events provide rapid feedback of subducting carbon fate to seafloor sedimentation dynamics. Here we demonstrate that sediment sorting creates distinct OC burial patterns in the Japan Trench: Prolonged seafloor residence enables preferential removal of labile OC components and result in a refractory subsurface OC pool. Conversely, rapid sediment burial shortens seafloor residence time and promotes subsurface anaerobic OC degradation. We further suggest that these mechanisms result in at least 37.6% loss of the OC subduction flux in accretionary margins due to early diagenetic and thermal alteration processes, while erosive margins only loss 11% during subduction and preferentially transfer thermally stable OC into subduction zones. Our work bridges surficial depositional regimes and deep carbon transfer, highlighting the need to consider depositional settings when refining subduction zone carbon budgets.
Zenodo (CERN European Organization for Nuclear Research) · 2026-05-08
datasetOpen accessSenior authorRaw geochronology data for publication "Paired U/Pb and 40Ar/39Ar constraints on the Middle Miocene hominoid sites and the fossil forest at Napudet, Turkana, Kenya" in GSA Bulletin, 10.1130/B37847.1, consisting of Ar isotope measurements for 40Ar/49Ar geochronology, laser ICP-MS elemental mapping, and ICP-MS U, Th, and Pb isotope data for U/Pb geochronology.
Zenodo (CERN European Organization for Nuclear Research) · 2026-05-08
datasetOpen accessSenior authorRaw geochronology data for publication "Paired U/Pb and 40Ar/39Ar constraints on the Middle Miocene hominoid sites and the fossil forest at Napudet, Turkana, Kenya" in GSA Bulletin, 10.1130/B37847.1, consisting of Ar isotope measurements for 40Ar/49Ar geochronology, laser ICP-MS elemental mapping, and ICP-MS U, Th, and Pb isotope data for U/Pb geochronology.
2026-03-14
articleOpen accessCorrespondingIn-situ U-Pb carbonate geochronology is a well-established technique that directly constrains the timing and rates of important geological processes including fluid flow, diagenesis, and tectonic events. However, the fundamental controls on U behaviour in carbonate minerals remain unclear, limiting geological interpretations. Knowledge gaps include the controls on U incorporation, the highly heterogeneous distribution of U at a crystal scale, and the incorporation of U with respect to other (redox-sensitive) elements. The application of synchrotron X-ray microspectroscopy (µXAS) is ideal for investigating these topics, as it can map chemical changes and measure the valance state of key elements at the micron-scale.Here we combine µXAS, in-situ laser ablation U-Pb carbonate geochronology, and EPMA analyses to temporally track U distribution, redox state, and dolomite-ankerite composition in a porphyry-epithermal system. Multiple generations of carbonate minerals record fluid conditions and processes which control the solubility and deposition of metals, including U. Results show that temporally distinct generations of carbonate record both oxidized UO22+ and reduced U4+ species within a single sample section. Mapping of individual carbonate crystals reveals that UO22+ and U4+ also occur within individual growth bands at a sub-millimetre scale, and in rare samples, may coexist. µXAS data from the sample suite demonstrate that local fluid conditions in the case-study mineralized system changed from more oxidized to more reduced over a period of ca. 16 Ma and corresponds with an increase in U levels in crystallizing carbonate.The preservation of two U oxidation states during discrete precipitation events requires U retentivity within older domains, indicating that the U-Pb carbonate geochronometer is robust under hydrothermal conditions (e.g., ~200–350ºC) and through rapid local redox state changes. Furthermore, crystal zones with abundant fluid/vapour inclusions linked to boiling processes coincide with higher levels of U in the carbonate and favourable U/Pb. Our results suggest redox changes and boiling conditions may be critical for both the deposition of ore minerals, as well as increased U uptake in carbonate minerals. Targeting carbonate domains with these features may therefore increase success for U-Pb geochronology. U-Pb carbonate dating combined with µXAS can track the temporal evolution of processes critical for metal deposition in long-lived and multistage hydrothermal-magmatic ore deposit settings.
Extreme plate boundary localization promotes shallow earthquake slip at the Japan Trench
Science · 2025-12-18 · 2 citations
articleThe 2011 moment magnitude 9.1 Tohoku-oki earthquake is exceptional among great earthquakes for having peak slip of ~50 to 70 meters on the shallowest portion of the plate boundary megathrust. Drill cores and geophysical logs from International Ocean Discovery Program Expedition 405 demonstrate that the megathrust preferentially develops at the top or base of the pelagic clay in the sedimentary layers present on the incoming Pacific Plate, where pronounced contrasts in physical properties occur. This preference results in a narrow, weak fault located at a major mechanical contact between frontal prism mud and subducted sediments, which enhances the tendency for shallow seismic slip, suggesting that the Japan Trench may be more susceptible to ruptures with large shallow slip than are margins without weak clays.
Canadian Journal of Earth Sciences · 2025-09-29
articleTectonic models for the evolution of the Canada Basin of the Arctic Ocean posit Jurassic–Cretaceous counterclockwise rotation of the Arctic Alaska terrane away from the Canadian Arctic Islands, translation along a strike–slip fault system, or some hybrid combination of the two. Here, we present evidence for post-Devonian deformation within the Porcupine fault system of northern Yukon and Alaska, which forms the southeastern boundary of the Arctic Alaska terrane. Neoproterozoic–Cretaceous strata exposed within the fault zone record polyphase deformation related to strike–slip displacement. Muscovite 40 Ar/ 39 Ar data from two samples collected north of the Porcupine River produced plateau or plateau-like segments at ca. 342–367 Ma and younger steps at ca. 105 Ma, consistent with initial cooling after emplacement of the Upper Devonian Old Crow plutonic suite and later Cretaceous–Cenozoic partial resetting. In contrast, samples from within the main strand of the fault system yield complex spectra with single steps as old as ca. 1779 Ma, highlighting contrasting thermal histories across it and post-Late Devonian truncation of the Old Crow plutonic suite. The timing of Mesozoic deformation is better constrained by U/Pb dating of calcite veins within the fault system, which yield an age of ca. 121 Ma. Coupled with field observations of unambiguous strike–slip related deformation within the Porcupine fault system, these geochronological data are consistent with translational or hybrid models for the opening of the Canada Basin.
Ancient metagenomics reveals subglacial microbiomes driven by oxygen availability
bioRxiv (Cold Spring Harbor Laboratory) · 2025-12-05
articleOpen accessAbstract Beneath Earth’s glaciers and ice sheets lies an aquatic realm where ice, water, rock, and microbial life interact, driving chemical reactions that can collectively influence the global carbon cycle, polar oceans, and climate. Efforts to describe subglacial microbiomes have been limited by the challenge of cleanly drilling through hundreds of meters of ice, such that only a few sites have ever been directly sampled. Here we use ancient metagenomics to present the first spatiotemporal characterization of subglacial bacteria and archaea. We extracted DNA from 25 subglacial precipitate samples, sedimentary accumulations of minerals that form in subglacial waters prior to exposure on the surface. The precipitates studied here formed between 16,000 and 570,000 years ago beneath the Antarctic and Laurentide Ice Sheets. We show that postmortem DNA damage patterns can reliably distinguish between ancient subglacial and modern surface taxa, and that this approach can enable reconstruction of subglacial microbiomes across poles and ice ages. Our analysis suggests that subglacial microbiomes are dominated by chemolithoautotrophs, ultra-small microbes, and taxa closely related to those found in deep subsurface or extreme cold and hypersaline environments. These microbiomes split into two distinct clusters distinguished by oxygen availability and redox conditions, irrespective of geography or age. Geochemical measurements of subglacial redox state, measured either indirectly via precipitate calcite Fe and Mn concentrations or directly via water reduction potential, reproduce these same two clusters exactly. Our findings describe how subglacial water redox states are held in balance by microbes, hydrology, and oxygen input from fresh subglacial meltwater, that we interpret to be controlled by the ice sheet response to past climate variations.
Polyphase Cretaceous and Cenozoic deformation along the Porcupine Fault System of Yukon and Alaska
Abstracts with programs - Geological Society of America · 2025-01-01
articleProceedings of the International Ocean Discovery Program. Expedition reports · 2025-12-19 · 3 citations
book-chapterOpen accessAntarctic subglacial trace metal mobility linked to climate change across termination III
The cryosphere · 2025-06-26 · 1 citations
articleOpen accessSenior authorCorrespondingAbstract. Antarctic meltwater is a significant source of iron that fertilizes present-day Southern Ocean ecosystems and may enhance marine carbon burial on geologic timescales. However, it remains uncertain how the nutrient flux from the subglacial system changes through time, particularly in response to climate, due to an absence of geologic records detailing element mobilization beneath ice sheets. In this study, we present a 25 kyr record of aqueous trace metal cycling in subglacial water beneath the David Glacier catchment measured in a subglacial chemical precipitate that formed across glacial termination III (TIII), from 259.5 to 225 ka. The deposition rate and texture of this sample describe a shift in subglacial meltwater flow following the termination. Alternating layers of opal and calcite deposited in the 10 kyr prior to TIII record centennial-scale subglacial flushing events, whereas reduced basal flushing resulted in slower deposition of a trace-metal-rich (Fe, Mn, Mo, Cu) calcite in the 15 kyr after TIII. This sharp increase in calcite metal concentrations following TIII indicates that restricted influx of oxygen from basal ice melt to precipitate-forming waters caused dissolution of redox-sensitive elements from the bedrock substrate. The link between metal concentrations and climate change in this single location across TIII suggests that ice motion may play an important role in subglacial metal mobilization and discharge, whereby heightened basal meltwater flow during terminations supplies oxygen to subglacial waters along the ice sheet periphery, reducing the solubility of redox-sensitive elements. As the climate cools, thinner ice and slower ice flow decrease subglacial meltwater production rates, limiting oxygen delivery and promoting more efficient mobilization of subglacial trace metals. Using a simple model to calculate the concentration of Fe in Antarctic basal water through time, we show that the rate of Antarctic iron discharge to the Southern Ocean is sensitive to this heightened mobility and may therefore increase significantly during cold climate periods.
Recent grants
Frequent coauthors
- 42 shared
Sidney R. Hemming
Lamont-Doherty Earth Observatory
- 28 shared
Kathleen Wooton
- 27 shared
Ken Ikehara
Geological Survey of Japan
- 26 shared
Gilbert N. Hanson
Stony Brook University
- 26 shared
S. J. Jaret
- 26 shared
Cecilia M. McHugh
- 25 shared
Jennifer M. Cole
- 25 shared
Min Luo
Shanghai Ocean University
Labs
Rasbury Isotope Lab (FIRST)PI
Education
- 1984
B.S.
Midwestern State University
- 1990
M.S.
Tulane University
- 1998
Ph.D.
SUNY Stony Brook
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