How mineralogy and slope aspect affect REE release and fractionation during shale weathering in the Susquehanna/Shale Hills Critical Zone Observatory

摘要: Abstract To understand the factors that control rare earth elements (REE) release and fractionation during shale weathering, we investigate REE contents in solid (bedrock, regolith, stream sediments), natural waters (stream, pore waters) from a first-order catchment developed entirely on gray shales central Pennsylvania, USA. Up to 65% of (relative parent bedrock) is depleted weathering profiles acidic organic-rich soils due chemical leaching. In addition, newly formed fine particles were also lost along with down-slope movement soil waters. Weathering south-facing slope show less depletion than those north-facing (33% vs. 45% average). We hypothesize different degrees two transects reflect history rates possible surface erosion rates, controlled by contrasting aspect-induced microclimate conditions. profiles, sequential extractions all preferential removal Middle (up 22% more) relative Light Heavy MREE rhabdophane. Furthermore, long-term phosphate mineral dissolution (e.g., rhabdophane) estimated at 10 − 15 − 14  mol m − 2  s − 1 under field conditions, based profiles. Strong positive Ce anomalies (average [Ce/Ce*] N value: 1.79) observed sediments, regolith point precipitation as compared other REE, generally oxidizing conditions release, transport, redistribution subsurface environments. Positive Eu [Eu/Eu*] 1.30) are attributed plagioclases bedrock. This study highlights use tracers for low-temperature geochemical processes.