Description
Eleven samples of argillite were collected from outside the aureole of the Emigrant Gap composite pluton, whereas 11 samples were collected from within the aureole. All 22 samples were analyzed for their REE concentrations. In order to avoid problems associated with the constant-sum constraint REE data were normalized to Ti (ppm) values on a sample-by-sample basis. The log to values of the resulting ratios were then calculated. F-tests were performed to assess the validity of equal or nonequal variances of log-transformed data for samples collected from outside and inside the aureole. The results of these tests consistently indicate that the variances of data from outside are not statistically unlike the variances of data from inside the aureole. Thus, student-t tests were conducted under the assumption of equal variances. The results of student-t tests indicate that the differences m means of log-transformed data on an element-by-element basis are not statistically different than zero. This result is significant because it suggests that the REE were immobile during the development of the contact metamorphic aureole associated with the Emigrant Gap composite pluton. Such a conclusion thus lends support to the commonly held, but often not well documented, belief that the REE are unaffected by pressures and temperatures common to the upper crust.
