Characterization of alteration products in tephra from Haleakala, Maui; a visible-infrared spectroscopy, Mossbauer spectroscopy, XRD, EMPA and TEM study

• Published in: Clays and clay minerals Vol. 55; no. 1; pp. 1 - 17
• Main Authors: Bishop, Janice L, Schiffman, Peter, Murad, Enver, Dyar, M. Darby, Drief, Ahmed, Lane, Melissa D
• Format: Journal Article
• Language: English
• Published: Boulder, CO Clay Minerals Society 01.02.2007; The Clay Minerals Society
• Subjects: alteration; Altered Tephra; Alunite; clay minerals; Earth sciences; Earth, ocean, space; East Pacific Ocean Islands; emission spectra; Empa; Exact sciences and technology; Haleakala; Hawaii; hydrothermal alteration; identification; igneous and metamorphic rocks; igneous rocks; infrared spectra; Infrared Spectroscopy; Jarosite; Mars; Maui; Maui County Hawaii; metasomatism; Mineralogy; Mossbauer; Mossbauer spectra; Oceania; Petrology; planets; Polynesia; pyroclastics; SEM; sheet silicates; Silicates; Smectite; Solfataric Alteration; spectra; sulfates; TEM data; terrestrial comparison; terrestrial planets; United States; volcanic rocks; weathered materials; X-ray diffraction data; XRD; Maui County Hawaii; Hawaii; Maui; Polynesia; Haleakala; chain silicates; oxides; X-ray diffraction; feldspar; aluminum; olivine; sulfates; Solfataric Alteration; XRD; Oceania; Mars; Mossbauer; Mossbauer spectroscopy; pyroxene; sheet silicates; silicates; craters; framework silicates; transmission electron microscopy; soils; infrared spectroscopy; scanning electron microscopy; nesosilicates; reflectance; jarosite; electron probe; emission spectroscopy; tephra; smectite; spectral signature; materials; clay minerals; alteration; EMPA; alunite; SEM; Altered Tephra
• ISSN: 0009-8604; 1552-8367
• DOI: 10.1346/CCMN.2007.0550101

Altered basaltic tephra from Haleakala, Maui, are characterized using multiple techniques in order to identify the minerals formed under a variety of conditions and to understand the soil formation processes here. We collected samples that are representative of typical bulk weathered material in the crater, as well as solfataric alteration in a hydrothermal environment. For this study X-ray diffraction, electron probe microanalysis, scanning electron microscopy and transmission electron microscopy are coupled with spectroscopic techniques including Mossbauer, visible-infrared reflectance, transmission infrared, and thermal infrared emission spectroscopies to analyze these samples. The unaltered tephra are composed of feldspar, glass, pyroxene and olivine. Observed alteration products include Fe oxides, phyllosilicates and sulfates, as well as SAED amorphous Al-Si-bearing material. These samples are potential analogs for altered volcanic material on Mars as the pedogenic influences and contact with plants and animals are minimal. Results from this study may help to determine spectral signatures of these samples that could be used for identification on Mars of the minerals observed here.