Samarium neodymium direct dating of fluorite mineralization

Fluid-inclusion microthermometry reveals that multiple pulses of moderately to highly saline aqueous to carbonic solutions caused greisenization and vein formation at temperatures above 200–250°C and up to 430°C at the early hydrothermal stage in the veins.Low calculated ∑REE concentration for bulk vein (15 ppm) compared to greisen (75 ppm), country rocks (173–224 ppm), and the intruding granite (320 ppm) points to overall low REE levels in the hydrothermal fluids emanating from the granite.

Fluid-rock and fluid-fluid interactions add further complexity to REE fractionation in natural systems, yet the applicability of experimentally determined partitioning has been implemented in geochemical, physical, and thermal evolution models of magmatic-hydrothermal systems at Strange Lake granitic pluton, Canada [3, 13] and in carbonatites such as those at Bayan Obo, China [14] and Songwe Hill, Malawi [15].

The greisen consists of coarse-grained quartz, muscovite, and fluorite, whereas the veins mainly contain quartz, calcite, epidote, chlorite, and fluorite in order of abundance.

A temporal and thus genetic link between the granite and the greisen/veins is established via high spatial resolution in situ Rb-Sr dating, supported by several other isotopic signatures (δC).

[32] of the Laxemar area outlining borehole locations and fracture lineaments (also indicated are villages and roads).

Thick black lines indicate underground extension of inclined drill cores. (b) Regional map of south Sweden indicating the location of the Transscandinavian Igneous Belt (TIB) in grey shade and the Laxemar area with arrow.

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