- Names
-
- Lucia Mandon
- Bethany L. Ehlmann
- Rebecca N. Greenberger
- Eric T. Ellison
- Lisa E. Mayhew
- Alexis S. Templeton
- Title
- Microscale hyperspectral mapping of a kilometer of mantle rocks: insights into low-temperature serpentinization systems from the Oman Drilling Program cores
- Abstract
- Characterizing products of water-rock interactions in low-temperature serpentinization of ultramafic rock is key to reconstructing fluid alteration histories of the crust and identifying subsurface habitable environments. We analyzed terrestrial peridotites from the Samail ophiolite using visible to near-infrared (VNIR-SWIR) microimaging reflectance spectroscopy. We continuously and homogeneously map hydration, mineralogy, and Fe partitioning in minerals at submillimeter resolution over 1-km of drilled cores to understand the character of alteration and develop metrics for conducting such analyses remotely. Our results confirm previous interpretations based on discrete samples: serpentinization is pervasive, and the dominant hydrated phase is Mg-bearing serpentine, incorporating variable Fe3+ and Fe2+. Residual Fe2+ in primary minerals (mainly orthopyroxene) and in secondary minerals (mainly serpentine) indicates further capacity for H2 production. At certain depths, brucite is replaced by Fe2+/ Fe3+/Mg-serpentine, which also generates H2, even in this low-temperature environment where magnetite production is disfavored. Increase in pyroxene with depth suggests alteration is incomplete and potentially ongoing. In gabbroic dike intrusions, we detect chlorite and serpentine, hydrated Ca-garnets, xonotlite, epidote, prehnite, and carbonates, evidence for Ca2+ mobility likely from the alteration of clinopyroxene. We highlight challenges in distinguishing serpentine–brucite mixtures from carbonates in reflectance spectra of natural rocks and report new VNIR-SWIR data for poorly-characterized low-temperature serpentinization minerals xonotlite and H-rich andradite-grossular garnets. These findings provide new mineralogical maps for correlation with fluid chemistry and microbiology to refine our understanding of habitability in the Samail ophiolite’s serpentinizing environments and offer a framework for interpreting analogous processes in the Solar System.
- Keywords
- imaging spectroscopy, visible, near-IR, mineral, serpentine, brucite, carbonate, Earth
- Content
- spectral data, earth sciences, planetary sciences
- Year
- 2026
- Journal
- Journal of Geophysical Research: Solid Earth
- Document type
- article
- Publication state
- submitted