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Dynamic crystallization of a eucrite basaltThe textural features produced in Stannern, a non-porpyritic representative of the eucrite basaltic achondrite class of meteorite, at differing cooling rates and various degrees of initial superheating were studied. Textures produced from mildly superheated melts were found to be fasciculate rather than porphyritic as the result of the cosaturated bulk chemistry of Stannern. The qualitative type of texture apparently depends mainly on the degree of initial superheating, whereas cooling rate exerts a strong influence on the coarseness of texture. Increasing the degree of superheating produces textures from intergranular/subophitic to fasciculate/porphyritic. With initial superheating to 1200 deg C the transition to quasi-porphyritic is controlled by cooling rate, but the development of phenocrysts is merely an overprint on the fasciculate background texture of the groundmass. The suppression of fasciculate texture is completed by a decrease of the degree of initial superheating below the plagioclast entry and suppression of quasi-porphyritic texture is completed by decrease of the degree of initial superheating below pyroxene entry; these qualitative changes do not seem to be produced by changes of cooling rate. A grain size/cooling rate dependence has been used to deduce the cooling rate of fasciculate-textured Stannern clasts (10.1 to 100 deg C/hr).
Document ID
19790055158
Document Type
Conference Proceedings
Authors
Walker, D. (Harvard Univ. Cambridge, MA, United States)
Powell, M. A. (Harvard Univ. Cambridge, MA, United States)
Hays, J. F. (Harvard University Cambridge, Mass., United States)
Lofgren, G. E. (NASA Johnson Space Center Houston, Tex., United States)
Date Acquired
August 9, 2013
Publication Date
January 1, 1978
Subject Category
LUNAR AND PLANETARY EXPLORATION
Meeting Information
Lunar and Planetary Science Conference(Houston, TX)
Funding Number(s)
CONTRACT_GRANT: NGL-22-007-247
CONTRACT_GRANT: NSR-09-051-001
Distribution Limits
Public
Copyright
Other