Lack of information regarding lithium(Li)crystal chemistry in numerous minerals,especially those containing trace amounts of Li(ranging from a few to tens of ppm),limits our understanding of Li isotopic fractionation ...Lack of information regarding lithium(Li)crystal chemistry in numerous minerals,especially those containing trace amounts of Li(ranging from a few to tens of ppm),limits our understanding of Li isotopic fractionation in pegmatites.In this study,we examined the Li isotopic composition and Li content in various Li-poor(e.g.,quartz or feldspar)together with Li-rich(sopdumene or lepidolite)mineral phases within granitic pegmatites.We compiled a comprehensive dataset,encompassing a broad spectrum of Li contents(ranging from a few to tens of thousands of ppm)and Li isotopic values(-8‰to 41‰).The minerals exhibit distinct Li isotopic signatures.Specifically,elbaite and beryl show the highest values,while biotite displays a negative average.Compared to individual minerals,whole rocks demonstrate lower Li isotopic values,with pegmatites exhibiting the highest and non-granitic pegmatite wall rocks showing the lowest.Our study also uncovers a clear“V”shape relationship between Li isotopic values and logarithm of Li contents,with different mineral groups occupying specific regions within this shape.Furthermore,a significant correlation was observed between average Li isotopic values and Li-O(OH,F)bond lengths in various minerals.These discoveries underscore the crucial role of crystal chemistry in shaping the Li isotopic behavior in pegmatites from a statistical perspective.展开更多
基金financially supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0802)。
文摘Lack of information regarding lithium(Li)crystal chemistry in numerous minerals,especially those containing trace amounts of Li(ranging from a few to tens of ppm),limits our understanding of Li isotopic fractionation in pegmatites.In this study,we examined the Li isotopic composition and Li content in various Li-poor(e.g.,quartz or feldspar)together with Li-rich(sopdumene or lepidolite)mineral phases within granitic pegmatites.We compiled a comprehensive dataset,encompassing a broad spectrum of Li contents(ranging from a few to tens of thousands of ppm)and Li isotopic values(-8‰to 41‰).The minerals exhibit distinct Li isotopic signatures.Specifically,elbaite and beryl show the highest values,while biotite displays a negative average.Compared to individual minerals,whole rocks demonstrate lower Li isotopic values,with pegmatites exhibiting the highest and non-granitic pegmatite wall rocks showing the lowest.Our study also uncovers a clear“V”shape relationship between Li isotopic values and logarithm of Li contents,with different mineral groups occupying specific regions within this shape.Furthermore,a significant correlation was observed between average Li isotopic values and Li-O(OH,F)bond lengths in various minerals.These discoveries underscore the crucial role of crystal chemistry in shaping the Li isotopic behavior in pegmatites from a statistical perspective.
