Publication
Names
  • H. Y. McSween
Title
Carbonaceous chondrites of the Ornans type - A metamorphic sequence
Abstract
The six identified carbonaceous chondrites classified as C3(O) (also known as the Ornans subtype or ornansites) are studied as a group. The Karoonda meteorite is also examined to determine whether it may be classified as a highly metamorphosed equivalent of the Ornans subtype. Petrographic and chemical similarities among these meteorites are discussed along with such systematic variations as textural, mineralogical, metallurgical, and chemical differences. Three metamorphic grades are delineated, chemical variations are correlated with the grades, and an attempt is made to determine why the Ornans meteorite belongs in a higher metamorphic grade on the basis of its chemical properties than on the basis of its petrographic characteristics. It is concluded that subtle differences among the meteorites may be related to small variations in the thermal metamorphism they have experienced.
Keywords
carbonaceous chondrites, CO chondrites, meteorite Kainsaz, meteorite Lance, meteorite Felix, meteorite Ornans, meteorite Isna, meteorite Warrenton, meteorite Karoonda, chemical analyses, petrographic analyses
Content
material-matter, planetary sciences
Year
1977
Journal
Geochimica et Cosmochimica Acta
Volume
41
Pages
477 - 491
Pages number
15
Document type
article
Publication state
published