DETERMINING CHONDRULE SIZE DISTRIBUTIONS FROM THIN-SECTION MEASUREMENTS

A method is described for correcting thin-section-derived chondrule si zes for three common sources of bias: (1) the non-equatorial sectionin g of chondrules, (2) the non-zero thickness of thin sections, and (3) the unequal probability of sectioning different size chondrules. Appli cation of the correction procedure to chondrule data from CO chondrite s results in a reduction of mean and median chondrule diameters, an in crease in minimum diameters, and transforms nearly log-normal distribu tions to distributions that conform to a Weibull probability function. The Weibull-function form of CO chondrule size distributions is simil ar to the form of chondrule distributions in ordinary chondrites obtai ned by disaggregation analyses.