Insights from mineral trace chemistry on the origin of NYF and mixed LCT + NYF pegmatites and their mineralization at Mangodara, SW Burkina Faso

Abstract

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Reevaluation of the K/Rb-Li Systematics in Muscovite as a Potential Exploration Tool for Identifying Li Mineralization in Granitic Pegmatites

“…St. Helens andesite StHs6/80-G, and Icelandic rhyolite ATHO-G. KL2-G was used as the primary reference material for all analyses, except for Tl for which no KL2-G data exist, and thus was reduced with NIST612 as the primary standard. For trace-element quantification, 27 Al (using data collected from prior EPMA sessions on the same grains) was used as an internal standard, with measured peaks on the iCAP-RQ at 7 Li, 9 Be, 23 Na, 24 Mg, 27 Al, 29 Si, 31 P, 44 Ca, 45 Sc, 49 Ti, 51 V, 52 Cr, 55 Mn 59 Co, 60 Ni, 63 Cu, 66 Zn, 71 Ga, 73 Ge, 75 As, 77 Se, 85 232 Th, and 238 U. Iolite version 4 [17] was used to correct measured isotopic ratios and elemental intensities for baselines, time-dependent laser-induced inter-element fractionation, plasma-induced fractionation, and instrumental drift. The mean and standard error of the measured ratios of the backgrounds and peaks were calculated after the rejection of outliers more than two standard errors beyond the mean.…”

“…Similarly, muscovite from mineralogically simple anatectic pegmatites from the Austroalpine area of the Eastern Alps in central Europe reported by Schuster et al [70] have a primitive geochemical signature and plot primarily in the poorly fractionated field of the K/Rb-Li diagram. The K/Rb ratios and Li values of muscovite from Group 2 (NYF) common pegmatites that lack REE-minerals but that may host accessory garnet, magnetite, or titanite (e.g., Mangodara area, Burkina Faso [66]) also plot within the poorly fractionated portion of the K/Rb-Li diagram (Figure 5).…”

Marker Minerals in Volcanics and Xenoliths—An Approach to Categorize the Inferred Magmatic Rocks Underneath the Present-Day Volcanic Landscape of Tenerife, Spain (NW African Rare Mineral Province)

“…Serandite and the Mn borate tinzenite are the only ones that show a direct link to the type III minerals in agpaitic pegmatites, phonolites, carbonatites and skarn deposits situated around the southern tip of Tenerife, while the less widespread rhodochrosite points to carbonatites at depth [181][182][183][184][185][186][187]. Bixbyite has been recorded as a cavity filling in rhyolites as well as in karst landforms [188][189][190][191]. Pyrophanite, the Mn analogue of ilmenite, is rather rare but occurs in a series of environments together with hollandite known from, e.g., iron formation deposits of Precambrian age, low-grade metamorphic deposits, A-type granites, mixed-type pegmatites and carbonatites [133,168,[192][193][194][195].…”