Volatile and lithophile trace-element geochemistry of Mexican tin rhyolite magmas deduced from melt inclusions

摘要: Abstract We have investigated the petrology and geochemistry of whole rocks from two small-volume, Sn- F-mineralized rhyolitec dome complexes Mexican tin rhyolite belt, Cerro el Lobo Pajaro, to determine volcanic degassing mineralizing processes in felsic igneous systems. The abundance distribution volatiles (H 2 O, B, F, Cl) lithophile trace ore elements (Li, Rb, Cs, Be, Sr, Y, Ce, Th, U, Nb, Sn, Mo) parental liquids were established by analyzing melt inclusions quartz. both rhyolites are variably enriched Li volatile constituents F Cl, some extremely Li, although not correspondingly enriched. Compositional variations also constrain magmatic differentiation. Melt evolution was dominated crystal fractionation, modified mass transport a Cl- H O-rich magmatic-hydrothermal fluid, resulted increasing abundances Cs (± Mo, Sn) liquids. apparently heterogeneous prior eruption. liquid contained gradients elements; comparatively less Al O 3 , CaO Th) present early-erupted, fractions liquid. Comparing compositions with mean constrains relative mobilities during after Sodium, fluorine, lithium, uranium, yttrium lost magmas Pajaro magma Nb as result eruptive posteruptive degassing. These geochemical relationships constraints on pre-eruptive distributions probably apply other and, moreover, high levels Cl enrichment maybe representative highly-evolved granitic genetically associated mineralization.