42 Geophysics/Geodynamics (Posters)

Added due to amt of discipline abstracts submitted.

Wednesday, 11 March 2026
9:00 AM - 12:00 PM
RCC, Lower Level Hall

Magnetic Variability in North Atlantic Mid-Ocean Ridge Basalts from IODP Expeditions 395/395C

Paper number: 42-1
Program: Technical Sessions
Time: 9:00 AM – 9:00 AM

Authors

Abstract

Mid-ocean ridge basalts (MORB) record the integrated effects of mantle source characteristics, crustal accretion processes, and post-emplacement modification. This study presents new rock magnetic and paleomagnetic results from basaltic cores recovered during IODP Expeditions 395 and 395C in the North Atlantic, with a focus on differences between V-Shaped Ridge (VSR) and V-Shaped Trough (VST) settings and the role of crustal age in shaping magnetic behavior. Site ages are at 2.8 Ma, 5.2 Ma, 12.4 Ma, 14.2 Ma and 32.4 Ma allowing assessment of how magnetic properties evolve during early crustal formation and subsequent aging.

Basalts recovered from VSTs exhibit higher natural remanent magnetization (NRM) intensities and larger Königsberger ratios, consistent with relatively fresh magnetic mineral assemblages and limited alteration. In contrast, VSR basalts show slightly lower remanence intensities and reduced Königsberger ratios, reflecting increased alteration, magnetic mineral oxidation, and changes in magnetic domain state. A strong age dependence is observed in magnetic properties, with Königsberger ratios systematically lower in older non-VSR/VST crust relative to younger VSR/VST samples.

These spatial and temporal patterns demonstrate that magnetic properties of oceanic crust are not uniform but are influenced by long-lived structural and mantle controls that govern magma supply, emplacement style, and cooling history, as well as by post-formation alteration pathways. The persistence of these differences away from the ridge axis suggests that early accretionary processes impart magnetic signatures that remain detectable despite subsequent modification. These results may provide a subsurface perspective on how pre-existing geodynamic and structural conditions influence the evolution of oceanic crust and inform interpretations of marine magnetic anomalies in slow-spreading environments.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411857

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