Mineralogy, geochemistry and petrology of the Catherwood and Kinley Saskatchewan meteorites

• Main Author: Fillo, Wayne Joseph
• Other Authors: Coleman, L.C.
• Format: Others
• Language: en
• Published: University of Saskatchewan 2012
• Online Access: http://library.usask.ca/theses/available/etd-05242012-132937/

<p>Separate aspects of the mineralogy, geochemistry and petrology of the Catherwood and Kinley Saskatchewan meteorites were investigated in this study.</p> <p>Since Catherwood and Kinley were found approximately twelve miles apart, it was the purpose of this study to determine whether they were actually from the same fall.</p> <p> Olivine, orthopyroxene, clinopyroxene, plagioclase, chlorapatite, troilite, kamacite and taenite, chromite, limonite and graphite are minerals typical of both meteorites.</p> <p>Textural features in the matrix and chondrules indicate that there was a period of high-temperature recrystallization in both Catherwood and Kinley. Absence of glassy chondrules, chondrules which diffuse into the matrix, dominance or anhedral and anhedral-subhedral olivine and orthopyroxene grains, uniform grain size, and smooth outline of some opaque minerals support this conclusion.</p> <p>Catherwood and Kinley have undergone significantly high stress levels. Olivine, orthopyroxene and chromite grains are fractured; mosaics of fine olivine grains are conspicuous; some chondrules occur as remnants and relicts; chondrules are commonly cracked, 'deformed', distorted and strained; taenite (γ-iron), an irreversible transition product, is present; veinlets and intergrowths of troilite and Ni-Fe have been formed subsequent to brecciation and droplets of troilite and Ni-Fe have been mobilized within chondrules. These features are all indicative of shock.</p> <p>Several features indicate that Catherwood and Kinley represent different falls. These include crustal differences and differences in bulk chemistry and mineral composition. Ringwoodite, majorite and maskelynite (irreversible phase transition products) are present only in Catherwood and pigeonite and ilmenite only in Kinley. Also, plagioclase, troilite, kamacite and taenite distributions are different in both chondrites. Catherwood chondrules are less abundant, smaller, less closely packed and more closely 'integrated' with the matrix than are the finley ohondrules. 'Barred', 'radiating', 'jacketed' and lithic chondrules are present in both chondrites, but their percentages differ resulting in different normative and modal distributions for the olivine and pyroxene of which they are composed. Catherwood has been subjected to higher stress levels and recrystallization temperatures as is evidenced by fracturing and veining, wavy extinction (strained grains), a lowering of birefringence in some grains, and by chondrules having been mylonitized. All these features are more prominent in Catherwood than in Kinley.</p> <p> Catherwood and Kinley are typical ordinary olivine hypersthene chondrites. Bulk chemistry, homogeneity of olivine and pyroxene (Fo=73 in Catherwood and 70 in Kinley; Fs=18 in Catherwood and 15 in Kinley), absence of glass (except for minor amounts or maskelynite in Catherwood), moderate amounts of plagioclase (An₁₀) some grains or which are large and show a good-to-excellent development; the presence or maskelynite, some chromite, and taenite (γ-iron), the kamacite-taenite-troilite assemblage, and extensive recrystallization classify both meteorites as L6 chondrites of Van Schmus and Wood (1967).</p> <p>Note:</p><p>Page 102 Figure 54 should read: Kinley. Prominent irregular fractures in subhedral to euhedral olivine (ol) and orthopyroxene (or). Plain light. <b>x 425</b>