Braun Jean-Jacques auteur aut IRD Riotte Jean auteur aut IRD Battacharya S. auteur aut IRD Violette A. auteur aut IRD Oliva P. auteur aut IRD Prunier J. auteur aut IRD Marechal J. C. auteur aut IRD Ruiz Laurent auteur aut IRD Audry S. auteur aut IRD Subramanian S. auteur aut IRD text journalArticle eng text/pdf born digital access The sources of REY-Th-U and long-term mass balance were assessed in the gneissic tropical forested Critical Zone Observatory of Mule Hole, India. The study relies on the characterization of the solid compartments (bedrock, soils, streambed and suspended sediments), on batch leaching experiments of the parent gneiss and on extractions of cation-exchangeable and iron-related pools of selected soil samples. The REY-Th-U primary reservoir is controlled by monazite, xenotime, thorite, allanite, bastnesite, titanite, apatite, and, to a lesser extent, by zircon. This accessory mineral assemblage was profoundly modified by episodes of metamorphism and hydrothermal activity. Allanite, bastnesite, titanite, and apatite are prone to break down at incipient weathering stage while monazite, xenotime and zircon are resistant minerals. On a long-term basis, REY are roughly inert in the immature saprolite and depleted in the soil cover and are strongly redistributed among secondary phases. LREE and HREY are mainly controlled by poorly crystallized secondary iron oxides and oxyhydroxides, and, to a lesser extent, by secondary phosphates (e.g., rhabdophane). Th, inert in the saprolite, is controlled by well-crystallized secondary iron oxides and oxyhydroxides and likely by secondary thorianite (ThO2). REY and Th are not easily mobilized during surface processes such as chelation by organic matter and uptake by plants. REY and Th are, by far, exported as suspended sediments associated with iron oxides. The U export by groundwater and suspended sediments dominates over those of streambed sediments and stream. specialized Upper Continental Crust chemical weathering erosion rare earth elements thorium uranium hydrologic sorting Critical Zone INDE 062 068 064 19 5 1611-1635 2018 1525-2027 https://www.documentation.ird.fr/hor/fdi:010073192 10.1029/2018gc007453 1525-2027 [F B010073192] https://www.documentation.ird.fr/hor/fdi:010073192 https://www.documentation.ird.fr/intranet/publi/2018/07/010073192.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2018-09-03 2023-07-11 fdi:010073192 fre