Identifying Lava-Water Interactions with VNIR: A Preliminary Study at Jordan Craters, Oregon
Abstract
Traditionally lava-water interactions are identified on planetary surfaces by identifying rootless cones or alteration minerals. However, in places where lava flows occurred in damp settings on Earth these identifiers do not always form, as they need specific ratios of water to lava or a long-lasting source of water. Besides these effects, lava-water interactions can also produce glassy quench textures within the basalt, a feature usually only visible on a petrographic microscope. Glassy textures scatter light instead of uniformly reflecting it and this will lower the albedo of the basalt, making this property potentially detectable with remote sensing techniques.
Visible Near Infrared (VNIR) data could be used to identify these water-quenched surfaces as the higher glass content would lower the albedo in comparison to surfaces that cooled slower. Changes in albedo could also be caused by alteration, surface roughness, or phenocryst content. The surfaces sampled in this study were all relatively flat, glassy, and free of visible alteration to control for these variables. A preliminary study was done at Jordan Craters, Oregon, a basalt flow roughly 3000 years in age, to test a new method for identifying lava-water interactions. VNIR data was collected using an ASD Halo on flat, glassy surfaces. Each data point was taken in triplicate to account for analytical error. Six unique morphologies with different quenching environments and glass content were identified and sampled; spatter, scoria, flow surfaces, water-quenched margins, air-quenched margins, and interior surfaces. The VNIR data sets show a trend between albedo and morphology, however, on its own, this does not prove that the trend is caused by relative glass content. Hand samples of each morphology were taken and analyzed in an SEM to support this hypothesis. The images were processed to show the modal percentage of glass, void space, olivine, and plagioclase. If the modal percentage of glass for each morphology has the same trend as the VNIR data, then it is likely that the trend is caused by glass content. This would mean that relative glass content in basalts can be identified using VNIR and margins of flow with higher glass content could be zones of lava-water interaction.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP21E2204R
- Keywords:
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- 6225 Mars;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 5415 Erosion and weathering;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5419 Hydrology and fluvial processes;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5494 Instruments and techniques;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS