01710nas a2200169   4500008004100000022002500041245010300066210006900169260001600238300001400254490000700268520117200275100001801447700001901465700001801484856003801502       1993                        eng d  a0008-4077, 1480-331300aComparison of the Rainy Ridge analcime phonolite sill and the Crowsnest volcanics, Alberta, Canada0 aComparison of the Rainy Ridge analcime phonolite sill and the Cr  cAug-01-1993  a1644-16490 v303 a<p><jats p=""> A 5&ndash;7&ensp;m thick analcime phonolite sill occurs in the middle of the Proterozoic Gateway Formation in southwest Alberta. The sill consists of sanidine, aegirine&ndash;augite, magnesian hastingsite, melanite with hydrogrossular rims, titanite, and minor biotite, apatite, and opaque minerals. Mineralogical and chemical similarities to the analcime-rich phases of the Cretaceous Crowsnest Formation found some 20&ensp;km to the north suggest a genetic relationship. Major differences are the presence of amphibole and hydrogrossular, minerals not reported in the Crowsnest Formation. The presence of amphibole as a primary hydrous phase in the Rainy Ridge sill indicates crystallization from a hydrous magma. Microprobe studies indicate a progressive enrichment of sodium in amphiboles and pyroxenes. An apparent difference in chemical composition and alteration behavior of primary analcime phenocrysts and groundmass analcime is interpreted to reflect crystallization of analcime from a hydrous melt at depth, followed by rapid transport to a shallow depth, and crystallization of the groundmass analcime and hydrogrossular rims. </jats></p>
1 aGoble, R., J.1 aTreves, S., B.1 aGhazi, A., M.  uhttp://dx.doi.org/10.1139/e93-142