부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.lithos.2003.11.003 Byline: Petr AernA1/2 (a), Morgan Masau (a)(b), Bruce E. Goad (a)(c), Karen Ferreira (a) Keywords: Leucogranite; Granitic pegmatite; Lepidolite; Petrology; Geochemistry; Petrogenesis Abstract: The Archean Greer Lake leucogranite intruded metabasalts of the Bird River Greenstone Belt in the southwestern part of the Superior Province of southeastern Manitoba. The considerably evolved, multiphase, peraluminous, B-, P-, and S-poor leucogranite (K/Rb 132 to 24) was probably generated by fault-friction-assisted anatexis of dominantly metatonalitic rocks and subsequent differentiation. The leucogranite produced interior, transitional, non-crosscutting pods of barren, beryl-columbite- and lepidolite-subtype pegmatites that solidified from local segregations of highly fractionated residual melt. Steep fractionation gradients characterize the granite-to-pegmatite transition, most conspicuously so in the case of the most evolved, Li, Rb, Cs, Be, Mn, Sn, Nb-Ta, F-rich, lepidolite-subtype pod AC #3 (with K/Rb [greater than or equal to] 16 and Cs 330 ppmwt in accessory K-feldspar, [greater than or equal to]2.5 and [less than or equal to]11,200 ppmwt, respectively, in lepidolite, Cs [less than or equal to]28,000 ppmwt in beryl, and Ta/(Ta+Nb) at. [less than or equal to] 0.95 in manganotantalite). The Greer Lake example documents beyond any doubt the igneous derivation of lepidolite-subtype pegmatites from a plutonic parent. Most cases of generally very scarce lepidolite-subtype pegmatites obscure this relationship, as the volatile-rich, highly fluid melts stable to relatively low temperatures commonly migrate to great distances from their plutonic sources. Author Affiliation: (a) Geological Sciences, University of Manitoba, Winnipeg, MB, Canada R3T 2N2 (b) Geology and Geophysics, University of New Orleans, New Orleans, LA 70148, USA (c) Inukshuk Exploration Inc., 21861 44A Avenue, Langley, BC, Canada V3A 8E1 Article History: Received 31 March 2003; Accepted 9 September 2004