『Abstract
　Dissolution cavities in weathered pebbly quartzite of the 〜2.5-Ga Moeda Formation at Capanema, Quadrilatero（後のaの頭に´） Ferrifero（iの頭は´） of Minas Gerais, Brazil, are decorated with suspended filaments of opaline silica. The filaments sustain xenotime-hematite aggregates in the open space. Xenotime occurs as inclusions in buds and botryoidal aggregates of hematite. The filamentous structures consist of strand-forming buds, hypha-like extensions, and thin strands that compose mat-like arrangements. They resemble microbial filaments that were replaced by opaline silica and fossilized. The occurrence of spherical hematite as protuberances on hematite-free opaline hyphae is interpreted as accretion of dissolved iron onto extracellular polymers. Phosphate sites in polymeric substances expelled from the microbial filaments might have adsorbed yttrium and heavy rare-earth elements from groundwater to the iron-accreting polymers. These would have resulted in botryoidal aggregates of hematite with xenotime inclusions. The presence of authigenic xenotime in the weathering zone opens a new possibility to constrain the evolution of lateritic profiles by xenotime geochronology.

keywords: Biomineralization; Xenotime; Hematite; Weathering; Siliciclastic rocks; Moeda Formation; Capanema; Minas Gerais; Brazil』

Introduction
Geological setting and sample material
Methods
Results
Discussion
Acknowledgments
References