Scanning electron microscopy characterization of iron, nickel and sulfur in chondrules from the Allende meteorite - Further evidence for between-chondrules major compositional differences

摘要: We analyze the relative contents and internal spatial elemental distribution of Fe, Ni S in minerals within selected individual chondrules a fragment Allende chondrite, as derived from scanning electron microscopy (SEM) - energy dispersive X-ray spectroscopy (EDS) analyses. Chondrules were to cover range micromagnetic properties in terms hysteresis coercivity and magnetization ratios. Variation appear correlated external internal morphologies mineralogical assemblages. In order identify mineral assemblages characterized by S, mathematical technique for image analysis was applied SEM-EDS images. The resulting compositional images display complexity composition microstructural morphologies chondrules. Chondrule c27b is characterized Fe-rich minerals and S poor, although concentrated rim. c40b, formed barred olivine, Fe poor has low S; homogeneously distributed olivine crystals. c53b spherical shape, except partly preserved rim that forms a bulge; with higher are observed chondrule interior. Chondrule c55b, porphyritic olivine type, more complex morphology, variable characteristic Results confirm closely spaced chondrules given sectors meteorite have major differences content and distribution, addition size, texture mineralogy, which support idea that chondrules underwent distinct thermal, shock, alteration evolutionary histories, related chondrule formation processes, early stages evolution planetary system.