See more from this Division: Topical Sessions
See more from this Session: Evolution of Simple Granite Systems (Haplogranites) and Rhyolites: A 50th Anniversary Perspective of the Tuttle and Bowen Studies
Abstract:
The concept of flux-rich magmas has been rejuvenated recently by reports of exotic melt inclusions (MI) within quartz from pegmatites. The high flux contents of these MI, however, are 1-2 orders of magnitude greater than both their abundance in the bulk rock and the concentrations indicated by relevant buffering mineral equilibria. One possibility is that the flux-rich MI represent boundary layer liquids trapped during rapid crystal growth from viscous granitic compositions.
If formed in the presence of flux-rich liquids, crystalline phases might be anomalously enriched in ordinarily incompatible B, P, and/or F. Experiments entailing rapid growth of alkali feldspars (Afs) from flux-rich liquids yield commensurately enriched crystals with B and P contents much higher than those found in the natural Afs. If a flux-rich melt is present during the consolidation of granitic pegmatites, even as narrow boundary layers along crystal surfaces, then an important main phase of the pegmatites, the Afs, do not record it.
See more from this Division: Topical Sessions
See more from this Session: Evolution of Simple Granite Systems (Haplogranites) and Rhyolites: A 50th Anniversary Perspective of the Tuttle and Bowen Studies