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Watson: A new link in the IIE iron chainWatson, which was found in 1972 in South Australia, contains the largest single silicate rock mass seen in any known iron meteorite. A comprehensive study has been completed on this unusual meteorite: petrography, metallography, analyses of the silicate inclusion (whole rock chemical analysis, INAA, RNAA, noble gases, and oxygen isotope analysis) and mineral compositions (by electron microprobe and ion microprobe). The whole rock has a composition of an H-chondrite minus the normal H-group metal and troilite content. The oxygen isotope composition is that of the silicates in the IIE iron meteorites and lies along an oxygen isotope fractionation line with the H-group chondrites. Trace elements in the metal confirm Watson is a new IIE iron. Whole rock Watson silicate shows an enrichment in K and P (each approximately 2X H-chondrites). The silicate inclusion has a highly equilibrated igneous (peridotite-like) texture with olivine largely poikilitic within low-Ca pyroxene: olivine (Fa20), opx (Fs17Wo3), capx (Fs9Wo14)(with very fine exsolution lamellae), antiperthite feldspar (An1-3Or5) with less than 1 micron exsolution lamellae (An1-3Or greater than 40), shocked feldspar with altered stoichiometry, minor whitlockite (also a poorly characterized interstitial phosphate-rich phase) and chromite, and only traces of metal and troilite. The individual silicate minerals have normal chondritic REE patterns, but whitlockite has a remarkable REE pattern. It is very enriched in light REE (La is 720X C1, and Lu is 90X C1, as opposed to usual chonditic values of approximately 300X and 100-150X, respectively) with a negative Eu anomaly. The enrichment of whole rock K is expressed both in an unusually high mean modal Or content of the feldspar, Or13, and in the presence of antiperthite.
Document ID
19950034105
Document Type
Reprint (Version printed in journal)
Authors
Olsen, Edward (Univ. of Chicago, Chicago, IL United States)
Davis, Andrew (Univ. of Chicago, Chicago, IL United States)
Clarke, Roy S., Jr. (Smithsonian Institution, Washington, DC United States)
Schultz, Ludolf (Max-Planck Institut fuer Chemie Mainz, Germany)
Weber, Hartwig W. (Max-Planck Institut fuer Chemie Mainz, Germany)
Clayton, Robert (Univ. of Chicago, Chicago, IL United States)
Mayeda, Toshiko (Univ. of Chicago, Chicago, IL United States)
Jarosewich, Eugene (Smithsonian Institution, Washington, DC United States)
Sylvester, Paul (Univ. of Chicago, Chicago, IL United States)
Grossman, Lawrence (Univ. of Chicago, Chicago, IL United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1994
Publication Information
Publication: Meteoritics
Volume: 29
Issue: 2
ISSN: 0026-1114
Subject Category
LUNAR AND PLANETARY EXPLORATION
Funding Number(s)
CONTRACT_GRANT: NAG9-111
CONTRACT_GRANT: NAG9-498
CONTRACT_GRANT: NAG9-47
CONTRACT_GRANT: NAG9-48
CONTRACT_GRANT: NAG9-51
CONTRACT_GRANT: DE-FG07-80-ER1072SJ
CONTRACT_GRANT: NSF EAR-89-20584
CONTRACT_GRANT: NAG9-54
Distribution Limits
Public
Copyright
Other