10 Undergraduate and Graduate Geoscience Student Showcase (Posters)

This is a hybrid oral-poster session. Presenters will submit one abstract for two presentations (3-minute lightning talk - morning, poster - afternoon). This will offer student presenters opportunities to practice a variety of science communication techniques. View the companion lightning talk session here.

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

Comparative Geochemical Analysis of Water–Rock Interactions in a Subterranean Lava Tube, Hawaiʻi

Paper number: 10-13
Program: Technical Sessions
Time: 9:00 AM – 9:00 AM

Authors

Abstract

This study examines water–rock interactions within a lava tube on the southeastern tip of the Island of Hawaiʻi to improve understanding of aqueous geochemistry in basaltic environments, including the Moon and Mars. Three sediment samples were collected from the wet lava tube floor, three rock samples from the east and west walls, and three mineral precipitates from wall surfaces. Five water samples were collected from the front, middle, and back of the tube. Temperature, pH, and salinity were measured in situ using a YSI, and samples were retained for ionic, isotopic, and metal analyses. Sediment and rock samples were crushed in a ball mill, pressed into pellets, and analyzed using portable X-ray fluorescence (pXRF) to determine elemental composition. Powder X-ray diffraction (PXRD) identified kaolinite, halloysite, calcite, thenardite, and gypsum. All rocks are classified as porphyritic alkali basalt and plot within the ocean island basalt (OIB) field on the Ti–V diagram. Rock samples are enriched in Mg, Cr, and Ni, with higher Ni in rock than sediment reflecting weathering and geochemical differentiation. Average field measurements indicate cool water (18.9 °C), near-neutral pH (7.68), and slightly brackish conditions (6.6 psu); isotopic compositions cluster between δ¹⁸O = −4.26 to −4.50‰ and δD = −25.8 to −26.9‰ (VSMOW), and major ions include Ca²⁺, Mg²⁺, and Cl⁻. These data indicate meteoric groundwater weakly mixed with seawater. Aqueous samples for metal analysis are still under analysis. Comparisons of rock, sediment, and groundwater chemistry clarify water–rock exchange processes relevant to planetary basaltic systems.

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

doi: 10.1130/abs/2026SE-411824

© 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.