Geology Research Works

Permanent URI for this collectionhttp://hdl.handle.net/1903/1594

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Characterization of Regolith And Trace Economic Resources (CRATER): An Orbitrap-based laser desorption mass spectrometry instrument for in situ exploration of the Moon
(Wiley, 2024-02-11) Ray, Soumya; Arevalo, Ricardo Jr.; Southard, Adrian; Willhite, Lori; Bardyn, Anais; Ni, Ziqin; Danell, Ryan; Grubisic, Andrej; Gundersen, Cynthia; Llano, Julie; Yu, Anthony; Fahey, Molly; Hernandez, Emanuel; Graham, Jacob; Lee, Jane; Ersahin, Akif; Briois, Christelle; Thirkell, Laurent; Colin, Fabrice; Makarov, Alexander
Rationale Characterization of Regolith And Trace Economic Resources (CRATER), an Orbitrap™-based laser desorption mass spectrometry instrument designed to conduct high-precision, spatially resolved analyses of planetary materials, is capable of answering outstanding science questions about the Moon's formation and the subsequent processes that have modified its (sub)surface. Methods Here, we describe the baseline design of the CRATER flight model, which requires <20 000 cm3 volume, <10 kg mass, and <60 W peak power. The analytical capabilities and performance metrics of a prototype that meets the full functionality of the flight model are demonstrated. Results The instrument comprises a high-power, solid-state, pulsed ultraviolet (213 nm) laser source to ablate the surface of the lunar sample, a custom ion optical interface to accelerate and collimate the ions produced at the ablation site, and an Orbitrap mass analyzer capable of discriminating competing isobars via ultrahigh mass resolution and high mass accuracy. The CRATER instrument can measure elemental and isotopic abundances and characterize the organic content of lunar surface samples, as well as identify economically valuable resources for future exploration. Conclusion An engineering test unit of the flight model is currently in development to serve as a pathfinder for near-term mission opportunities.
Oxygen Fugacity of Global Ocean Island Basalts
(Wiley, 2024-01-27) Willhite, Lori N.; Arevalo, Ricardo Jr.; Piccoli, Philip; Lassiter, John C.; Rand, Devin; Jackson, Matthew G.; Day, James M. D.; Nicklas, Robert W.; Locmelis, Marek; Ireland, Thomas J.; Puchtel, Igor S.
Mantle plumes contain heterogenous chemical components and sample variable depths of the mantle, enabling glimpses into the compositional structure of Earth's interior. In this study, we evaluated ocean island basalts (OIB) from nine plume locations to provide a global and systematic assessment of the relationship between fO2 and He-Sr-Nd-Pb-W-Os isotopic compositions. Ocean island basalts from the Pacific (Austral Islands, Hawaii, Mangaia, Samoa, Pitcairn), Atlantic (Azores, Canary Islands, St. Helena), and Indian Oceans (La Réunion) reveal that fO2 in OIB is heterogeneous both within and among hotspots. Taken together with previous studies, global OIB have elevated and heterogenous fO2 (average = +0.5 ∆FMQ; 2SD = 1.5) relative to prior estimates of global mid-ocean ridge basalts (MORB; average = −0.1 ∆FMQ; 2SD = 0.6), though many individual OIB overlap MORB. Specific mantle components, such as HIMU and enriched mantle 2 (EM2), defined by radiogenic Pb and Sr isotopic compositions compared to other OIB, respectively, have distinctly high fO2 based on statistical analysis. Elevated fO2 in OIB samples of these components is associated with higher whole-rock CaO/Al2O3 and olivine CaO content, which may be linked to recycled carbonated oceanic crust. EM1-type and geochemically depleted OIB are generally not as oxidized, possibly due to limited oxidizing potential of the recycled material in the enriched mantle 1 (EM1) component (e.g., sediment) or lack of recycled materials in geochemically depleted OIB. Despite systematic offset of the fO2 among EM1-, EM2-, and HIMU-type OIB, geochemical indices of lithospheric recycling, such as Sr-Nd-Pb-Os isotopic systems, generally do not correlate with fO2.