High precision oxygen three-isotope ratios were measured for four mineral phases (olivine, low-Ca and high-Ca pyroxene, and plagioclase) in equilibrated ordinary chondrites (EOC) using a secondary ion mass spectrometer. Eleven EOCs were studied that cover all groups (H, L, LL) and petrologic types (4, 5, 6), including S1-S4 shock stages, as well as unbrecciated and brecciated meteorites. SIMS a...

We reexamine the relationship between pyroxene composition and near-infrared absorption bands, integrating measurements of diverse natural and synthetic samples. We test an algorithm (PLC) involving a two-part linear continuum removal and parabolic fits to the 1 and 2 lm bands—a computationally simple approach which can easily be automated and applied to remote sensing data. Employing a suite o...

Lodran is a unique meteorite consisting of roughly equal amounts of metal, olivine, and pyroxene with minor amounts of sulphide, chromite, phosphide, chrome-diopside, and a new phase with a composition close to (K,Na)A1SisO12. Zahringer reported planetary-type rare gases in both the metal and silicates, suggesting a primitive nature. The pyroxene composition is Fs13.s with little variation. Oli...

Introduction: High-Ca pyroxene and plagioclase are typically present as minor phases in diogenites [1]. However, although the trace element content of diogenite orthopyroxene has been measured in a number of studies e.g., [2, 3]; almost no trace element data is available for the high-Ca pyroxene and plagioclase with which it routinely coexists in these meteorites. These data could provide insig...

We investigate the ability to refine pyroxene composition and modal abundance from laboratory and remotely acquired spectra. Laboratory data including the martian meteorites, Shergotty, Zagami, MIL03346, and ALH84001 as well as additional pyroxene-rich spectra obtained from the OMEGA (Observatoire pour la Minéralogie, l’Eau, les Glaces, et l’Activité) spectrometer for Mars are characterized usi...

Introduction: Martian meteorites have various characteristics, which are direct clues to understanding the petrogenesis of Mars rocks. The variation in oxidation state among the Martian meteorites must have important implications for redox conditions of the Martian crust/mantle and overall differentiation on Mars. Wadhwa [1] and Herd et al. [2] reported that Martian basalts were formed under a ...

Microprobe analyses of Ca-rich pyroxenes crystallized in the melting ranges of a magnesian alkali basalt, a transitional basalt, an olivine tholeiite, a tholeiitic andesite, and an augite leucitite at pressures between 8 and 45 kb show complex variation. Ca-poor pyroxene precipitated only from the alkali basalt at pressures between 14 and 18 kb. Pyroxene falling near the Di-Hed join in the pyro...

Introduction: Crystal size distribution (CSD) analysis is a useful technique for quantifying textural information and linking petrographic texture to original crystallization conditions [1]. In previous studies we have conducted CSD analyses of multiple thin sections of nakhlite meteorites [2], and several basaltic and mixed shergottites [3,4]. Based on results of these analyses, we derived cry...