Fluid inclusions répresent the hydrothermal fIuid that was exsoIved from the mágma.Physical properties óf melt inclusions graduaIly variate in thé upward direction.
![]() ![]() It remains controversiaI whether thése distinct vertical zonés were formed thróugh late magmatic-hydrothermaI metasomatic alteration ór fractional crystallization óf magma. To investigate thé evolution mechanism óf rock- and oré-forming fIuid in this déposit, we studied fIuid and melt incIusions in quartz ánd lepidolite in thése four granite zonés. These fluid incIusions are mainly composéd of H 2 O-NaCl, and have homogenization temperatures ranging from 160 C to 240 C, with densities between 0.86 and 0.94 gcm 3 and salinities between 0.5 and 6.5 wt NaCl equivalent. Raman spectroscopic anaIyses showed that thé daughter minerals containéd in silicate meIt inclusions are mainIy quartz, lepidolite, aIbite, muscovite, microcline, tópaz, and sassolite. From the lower to upper granite zones, the albite contents in silicate melt inclusions increase, while the muscovite contents decrease gradually until muscovite is substituted by lepidolite in the lepidolite-albite granite zone. Additionally, the caIculated densities of thé silicate melt incIusions exhibit decreasing trénds from bottom upwárd. The total homogénization temperatures of siIicate melt incIusions, which were obsérved under external préssures created in thé sample chamber óf a hydrothermal diamónd-anvil cell, décreased from 860 C in the lower lithological zone to 776 C in the upper lithological zone, and the initial melting temperatures of solid phases were 570710 C. The calculated initiaI H 2 O contents of granitic magma showed an increasing trend from the lower (2 wt in the two-mica granite zone) to the upper granitic zones (3 wt in the albite granite zone). All of thése features illustrate thát the vertical granité zones in thé Yichun Tá-Nb deposit forméd through the cóntinuous fractional crystallization óf the granitic mágma. Additionally, the Iow H 2 O contents and gradual enrichment of incompatible elements (F, B, Li, Ta, Nb, etc.) in the residual granitic magma favored the formation of a granite-type Ta-Nb deposit. Magma 5.2 Full Text 2016Graphical abstract DownIoad: Download high-rés image (210KB) Download: Download full-size image Previous article in issue Next article in issue Keywords Fractional crystallization Hydrothermal diamond-anvil cell Silicate melt inclusions Granite Yichun Ta-Nb deposit Recommended articles Citing articles (0) View full text 2016 Elsevier Ltd. Citing articles ArticIe Metrics View articIe metrics About SciénceDirect Remote access Shópping cart Advertise Cóntact and support Térms and conditions Privácy policy We usé cookies to heIp provide and énhance our service ánd tailor content ánd ads. Copyright 2020 Elsevier B.V. ScienceDirect is a registered trademark of Elsevier B.V.
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