Chemical weathering in subtropical basalt-derived laterites: A mass balance interpretation (Misiones, NE Argentina)

Campodonico, Verena Agustina; Pasquini, Andrea I.; Lecomte, Karina Leticia; García, María Gabriela Nachón; Depetris, Pedro J.

doi:10.1016/j.catena.2018.10.027

Cited by 27 publications

(11 citation statements)

References 69 publications

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“…ising Scandium During Intense Weathering Processes In the lateritic duricrust, isocon analyses indicate the possibility of Sc remobilisation from upper levels during intense lateritic weathering, also observed in lateritic profiles from New Caledonia (Teitler et al, 2019;Ulrich et al, 2019) and Argentina (Campodonico et al, 2019). This mobility can be explained considering smaller-scale observations.…”

Section: Small-scale and Long-term Mechanisms Mobil-mentioning

confidence: 75%

“…Recent work has shown that Sc speciation in lateritic duricrust is dominated by adsorption on goethite while substitution is minor (Chassé et al, 2017), although Ulrich et al (2019) suggest that Sc could be incorporated into the goethite structure (Ulrich et al, 2019). In addition, conservative behaviour of Sc is at odds with evidence of depletion at the top of lateritic duricrusts (Campodonico et al, 2019;Teitler et al, 2019). Atomic-scale processes at the interface between minerals and aqueous solutions exert a major control on the fate of metals in soils and sediments (Brown and Calas, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Australian laterites reveal mechanisms governing scandium dynamics in the critical zone

Chassé

Griffin

O’Reilly

et al. 2019

Geochimica et Cosmochimica Acta

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Scandium is often considered as immobile during chemical weathering, based on its low solubility. In contrast to other conservative (i.e. relatively immobile) elements incorporated into accessory minerals resistant to weathering (e.g. zirconium, thorium or niobium), the scarcity of scandium minerals indicates that the processes accounting for scandium's immobilisation are distinctive. However, the evolution of scandium speciation during weathering is unknown, limiting the understanding of the processes controlling its dynamics in the critical zone. Exceptional scandium concentrations in east Australian laterites provide the possibility of unravelling these mechanisms. We follow scandium speciation through thick lateritic profiles (> 30 m) using a multiscale mineralogical and spectroscopic approach involving electron microprobe, laser-ablation-inductively coupled plasma mass spectrometry, selective leaching and X-ray absorption near-edge structure spectroscopy, complemented by mass-transfer calculations. We show that the initial reservoir of scandium contained in the parent rock is preserved under reducing conditions occurring in the lowest horizons of the profiles. The dissolution of scandium-bearing clinopyroxene generates smectitic clays that immobilise and concentrate scandium. It is subsequently trapped in the lateritic duricrust by goethite. Scandium mobilisation appears in this horizon and increases upward as a result of the dissolution of goethite, possibly assisted by dissolved organic matter, and the precipitation of hematite. Molecular-scale analyses demonstrate that changes in speciation govern scandium dynamics, with substitution in smectitic clays and adsorption on iron oxyhydroxides playing a crucial role in scandium immobility in the saprolite and lower lateritic duricrust. The higher affinity of scandium for goethite relative to hematite drives scandium mobilisation in the upper lateritic duricrust, leading to its concentration downward in the lower lateritic duricrust. These successive mechanisms illustrate how the unique complexity of the critical zone leads to scandium concentrations that may form new types of world-class scandium deposits. Comparison with conservative elements and with rare-earth elements, expected to have similar geochemical properties, emphasizes the unique behaviour of scandium in the critical zone. While scandium remains immobile during the early stages of weathering, intense and long-term alteration processes, observed in lateritic contexts, lead to scandium mobilisation. This study highlights the dependence of scandium mobility on weathering conditions.

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Section: Small-scale and Long-term Mechanisms Mobil-mentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Australian laterites reveal mechanisms governing scandium dynamics in the critical zone

Chassé

Griffin

O’Reilly

et al. 2019

Geochimica et Cosmochimica Acta

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“…2.1 成矿母岩特征目前钪的主要来源是白云鄂博中富霓辉石的尾矿以及铝土矿赤泥 [21] . 但是世界上还存在一些潜在的和风化作用有关的钪资源, 主要分布在澳大利亚 [18] 、俄罗斯 [22] 、新加里多尼亚 [23,24] 和阿根廷东北部 [25] . 与其他稀土元素不同的是, 风化壳型钪矿的形成主要和基性-超基性岩有关.…”

Section: 风化壳型钪矿床的主要特点和成矿过程unclassified

The genesis of regolith-hosted rare earth element and scandium deposits: Current understanding and outlook to future prospecting

Zhou¹,

Li²,

Wang³

et al. 2020

Chin. Sci. Bull.

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“…The mobility of elements during chemical weathering can be assessed by means of mass balance calculations. Mass balance interpretations have been applied for quantifying the mobility of elements in loess-paleosol sequences (e.g., Yang et al, 2006;Sun et al, 2018) as well as in other environments and materials (e.g., Girty et al, 2003;Campodonico et al, 2014;Girty et al, 2014;Campodonico et al, 2019). The Woronow and Love (1990) log-ratio technique was employed here to quantify the elemental fractionation and mass changes that occurred between loess and paleosols.…”

Section: Weathering Assessmentmentioning

confidence: 99%

“…Several compositional diagrams have been proposed in the literature to determine the relationship between geochemical composition, provenance and tectonic setting (e.g., Bathia, 1983;Roser and Korsch, 1986;Floyd and Leveridge, 1987). Such diagrams have been widely used to constrain the provenance of sediments and sedimentary rocks, but also of atmospheric dust, soils and loess-paleosol sequences (e.g., Sun et al, 2006;Muhs and Budahn, 2009;Ahmad and Chandra, 2013;Dehbandi and Aftabi, 2016;Babeesh et al, 2017;Muhs et al, 2018;Campodonico et al, 2019). Numerous trace elements ratios and plots that employ trace elements have proven to be more appropriate to identify sedimentary provenance than some traditional diagrams that involve major elements (e.g., Bathia, 1983;Roser and Korsch, 1986) which are not always reliable (e.g., Armstrong-Altrin and Verma, 2005;Caracciolo et al, 2012).…”

Section: Provenancementioning

confidence: 99%

Geochemistry of a Late Quaternary loess-paleosol sequence in central Argentina: Implications for weathering, sedimentary recycling and provenance

2019

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A loess-paleosol sequence in the Pampean Plain, central Argentina was analyzed geochemically, in order to evaluate the weathering signature and sedimentary recycling as well as to analyze the origin of these loessic sediments. Corralito I sequence is composed of three paleosols and a buried soil separated by loess layers. The loess-paleosol sequence shows a similar geochemical composition throughout, suggesting that pedogenesis has not been intense enough to mask the chemical signature of the parent material. Weathering indices (CIA, CIW, PIA and LWI), elemental ratios (Rb/Sr, CaO/TiO 2 and Na 2 O/TiO 2), and the A-CN-K ternary diagram indicate incipient chemical alteration for this sequence, compatible with a weathering-limited regime. As expected, paleosols (CIAs~60) exhibit a slightly higher chemical alteration than loess layers (CIAs~58). Mass balance calculations reveal the losses of some major oxides (i.e., CaO, Na 2 O) and Sr in the buried soil and paleosols compared to its loess mantles, reflecting the weathering of plagioclase. Besides, the losses of K 2 O and Ba in the buried soil and paleosols I and II, when compared to its loess layers, suggest the chemical alteration of Kfeldspar. The chemical alteration of volcanic glass is evidenced by the relative losses of As in almost all levels. Conversely, the relative gains of Fe 2 O 3 and MgO reveal that pyroxenes and amphiboles or Fe oxy-hydroxides are concentrated in paleosols and the buried soil compared to its loess mantles. The geochemical approach used to constrain the origin of these Pampean Plain loessic sediments indicates they derive mainly from the Andean region. Conversely, the Pampean ranges, the Paraná River basin and Uruguayan Precambrian outcrops, which were pointed out as minor local sources, do not contribute significantly to the loess deposits. This work also shows that Corralito I loess-paleosol sequence and other loess samples from Argentina do not evidence sedimentary recycling, suggesting that these Pampean Plain loess deposits are mainly composed by young materials derived from undifferentiated volcanic rocks. The chemical composition of loessic sediments reveals the composition of the dust sources and reflects the modifications induced during transport and post-depositional weathering (e.g., Ahmad and Chandra, 2013). Different geochemical approaches have been used to analyze chemical weathering and provenance in loess-paleosol sequences in various regions of the world (e.g.,

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Chemical weathering in subtropical basalt-derived laterites: A mass balance interpretation (Misiones, NE Argentina)

Cited by 27 publications

References 69 publications

Australian laterites reveal mechanisms governing scandium dynamics in the critical zone

Australian laterites reveal mechanisms governing scandium dynamics in the critical zone

The genesis of regolith-hosted rare earth element and scandium deposits: Current understanding and outlook to future prospecting

Geochemistry of a Late Quaternary loess-paleosol sequence in central Argentina: Implications for weathering, sedimentary recycling and provenance

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