Contrasting coronas: microscale fluid variation deduced from monazite breakdown products in altered metavolcanic rocks associated with the Grängesberg apatite-iron oxide ore, Bergslagen, Sweden. (3rd April 2022)

• Record Type: Journal Article
• Authors: Majka, Jarosław; Włodek, Adam; Jonsson, Erik; Högdahl, Karin
• Is Part Of: GFF. Volume 144:Number 2(2022)
• Page Start: 89
• Page End: 96
• Publication Date: 2022-04-03
• Subjects: Fluids -- rare earth elements -- accessory phosphates -- Bergslagen ore province; Geology -- Scandinavia -- Periodicals; Geology -- Periodicals; 554.8
• DOI: 10.1080/11035897.2022.2083224
• Languages: English
• ISSNs: 1103-5897

Abstract

ABSTRACT: Three different types of secondary coronas developed around monazite-(Ce) were discovered in altered metavolcanic rocks closely associated with the Palaeoproterozoic apatite-iron oxide ore deposit in Grängesberg, Sweden. All three types of reaction coronas include fluorapatite that is either rimmed by allanite-(Ce), REE-fluorocarbonate(s), or hingganite-(Y). The latter mineral has not been previously observed among monazite breakdown products. A unique feature of the described reaction coronas around monazite is their spatial proximity to each other, not exceeding a few hundreds of micrometres. We infer that the observed, strongly contrasting monazite breakdown assemblages highlight the presence of a heterogeneous fluid that mediated these microscale decomposition reactions. Thus, it is emphasized that metasomatic fluid variability in natural systems may often be too large to be predicted and reproduced experimentally.