29 Undergraduate Research, Part II (Posters)

Session showcases undergraduate research. Topics include geoscience-related fields (e.g., resources, hydrology, oceanography, climate, environmental science, geospatial, informatics, health, policy, & education). Undergraduate student/s must be the lead author/s presenters with faculty mentor/s as co-author/s. This session welcomes both poster and oral presentation submissions.

Tuesday, 10 March 2026
9:00 AM - 5:00 PM
RCC, Lower Level Hall

Downhole Alteration and Magnetic Property Variabilities of Basaltic Rocks with Different Cooling Rates from the Reykjanes Ridge (IODP Expedition 395C)

Paper number: 29-31
Program: Technical Sessions
Time: 9:00 AM – 9:00 AM

Authors

Abstract

Paleomagnetic studies of basaltic rocks provide critical insights into oceanic crust evolution. Indeed titanomagnetite, a key ferromagnetic mineral in basalts, exhibits grain-size- dependent behaviors that influence magnetic retention. Prior paleomagnetic research on titanomagnetite has focused on synthetic samples or limited regions, leaving natural systems with complex cooling histories underexplored. Basaltic samples rich in titanomagnetite collected during International Ocean Discovery Program (IODP) Expedition 395C from the Reykjanes Ridge were evaluated on how downhole alteration processes and cooling rates affect different basalt types: pillow lava, sheet/massive flows, and lava. Seventy-two cubic (8 cm 3 ) basalt samples from Hole U1555I, underwent alternating field demagnetization, magnetic hysteresis test, isothermal remanent magnetization (IRM) test, temperature dependence of magnetic

susceptibility, and thin section analysis. These methods quantify coercivity and magnetic remanence, identify domain-state transitions and minerals present, and compare alteration percentiles. Magnetic hysteresis properties reveal grain-size dependence, with a clear single- domain grouping identifying the quickly cooled pillows. Flows and lavas show overlap in hysteresis behavior, with the flows favoring multi-domain characteristics. Due to limited samples, thin section analysis was constrained to rapidly cooling pillow basalts and slowest cooling lavas. Heavy hydrothermal alteration can be seen in vesicles, veins, large crystals, and the matrix of all thin sections. Textures, including variolitic, vesicular, skeletal, dendritic, and sieve, are observed in thin sections, indicating that the samples cooled quickly.

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

doi: 10.1130/abs/2026SE-411748

© Copyright 2026 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.