Pine Creek Geosyncline. Statistical treatment of whole rock chemical data

Statistical treatment of whole rock analyses was undertaken on 350 specimens collected within the Pine Creek Geosyncline which were analysed for 41 elements. Particular emphasis is given to main host rocks associated with uranium deposits, and to granitoids. Statistical methods employed include cluster analysis, correlation coefficients, means and variances. Correlations on the rock units that are host to the uranium deposits give the following results for uranium at the 99 percent confidence limit: Cahill Formation: U correlates with W, As, Nb, Mo, Pb, Li, Sc and Co; Masson Formation: U correlates with Li; Koolpin Formation: U correlates with Ti, P, Y, Ni, Cu, Zn, W, Nb, Pb and Li. The large number of rocks analysed in the Cahill Formation (143) made it possible to exercise correlation 'filters' at the 99 percent confidence limit, namely: a) U in excess of 500 ppm - U correlates with As, Nb, La, Ce, Mo, Pb and Co; b) U in excess of 40 ppm - U correlates with As, Nb, Mo, Pb, Sc and Co; c) U less than 40 ppm - U correlates with P; d) U less than 30 ppm - U shows no correlation. The correlation of uranium with the above elements suggests that they were transported in the uranium mineralising solutions. Of the granitoids studied the mafic-rich Nimbuwah Complex has the highest degree of correlation and clustering, which is attributed to its exclusively I-type nature and limited compositional range. The other granitoids investigated are of mixed S- and I-type parentage and range from mafic to felsic varieties; these factors account for the low to moderate degree of correlation of the elements. (author)