Open AccessVisible and near‐infrared reflectance spectroscopy of pyroxene‐bearing rocks: New constraints for understanding planetary surface compositions
Author(s) -
Pompilio Loredana,
Sgavetti Maria,
Pedrazzi Giuseppe
Publication year - 2007
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006je002737
Subject(s) - pyroxene , mineralogy , geology , spectroscopy , petrography , spectral line , mineral , infrared spectroscopy , olivine , analytical chemistry (journal) , materials science , chemistry , physics , organic chemistry , astronomy , metallurgy , chromatography , quantum mechanics
Laboratory visible and near‐infrared reflectance spectra of solid rock slabs, mineral separates and systematic mixtures were simultaneously investigated. We apply an empirical approach to evaluate spectra, in order to achieve qualitative and quantitative information. We use cumulates (mostly norites, leuconorites, melanorites and anorthosites) belonging to the Bjerkreim‐Sokndal Layered Intrusion, a sequence of genetically related rocks with simple textures. Laboratory spectra are measured on slightly polished rock slabs in the 350‐ to 2500‐nm interval and directional‐hemispherical reflectance geometry. Composition is determined using traditional techniques other than reflectance spectroscopy. We find that: (1) band minima measured on rock spectra are strongly influenced by the concurrent effects due to modal abundance of the spectroscopically active mineral and mineral chemistry; (2) band depths can be used for semiquantitative analyses, limited to the set of rocks investigated; (3) the spectral parameters derived from powdered pyroxene are in agreement with previously published calibrations; (4) the mineral mixture systematics can be reasonably considered as linear, when pyroxene is mixed with neutral components; and (5) the empirical evaluation of solid rock surface spectra needs further insights to give a great improvement to planetary researches. In addition, genetic sequences of rocks should be investigated in detail to help the geological interpretation of planetary evolution. Therefore more laboratory and analytical studies are required in order to understand the influence of composition and petrographic textures on the spectral analysis.