24 Undergraduate Research Posters

This poster session highlights geoscience research conducted and presented by undergraduate students. Abstracts must be written by students (but may include non-student co-authors). Research topics may include any area of the earth sciences.

Thursday, 23 April 2026
8:00 AM - 5:30 PM
LMH, 5th Floor Chapel

Magnetic properties and density of serpentinized lherzolites: Lherz Massif, France

Paper number: 24-10
Program: Technical Sessions
Time: 8:15 AM – 8:15 AM

Authors

Abstract

Serpentinization alters the mineralogy and physical properties of peridotites, producing measurable changes in density, magnetism, and other petrophysical characteristics. Despite its significance, petrophysical data for serpentinized lherzolites remain scarce compared to more commonly studied harzburgites and dunites. This study presents new petrophysical data from partially serpentinized lherzolites of the Lherz Massif (French Pyrenees), sampled from surface exposures down to ~200 m depth within the Gouffre Georges cave. Specific mass, low-field magnetic susceptibility, natural remanent magnetization, magnetic hysteresis, and saturation magnetization were measured to evaluate the relationship between petrophysical properties and the degree of serpentinization in these peridotites.

Density provides the most consistent proxy for the degree of serpentinization, with a corresponding decrease in density as serpentinization increases. In contrast, low-field magnetic susceptibility exhibits a weak correlation with density, reflecting the influence of magnetite grain size variability and different reaction pathways. This behavior differs from the widely used model of Toft et al. (1990), which predicts a strong logarithmic increase in magnetic susceptibility alongside the degree of serpentinization and treats magnetic susceptibility as a quantitative proxy for alteration extent. Our results demonstrate that this assumption does not extend to lherzolites, where magnetite domains, grain size, and alteration pathways differ from those in commonly studied harzburgites and dunites.

This study improves the petrophysical characterization of serpentinized peridotites and shows how petrophysical properties evolve during serpentinization. By establishing petrophysical datasets specific to lherzolites, this study improves the characterization of partially serpentinized peridotites and strengthens the application of gravity and magnetic inversion methods used to delineate peridotite bodies at depth.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3

doi: 10.1130/abs/2026CD-410951

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