Multiscale physical–chemical analysis of the impact of fracture networks on weathering: Application to nickel redistribution in the formation of Ni-laterite ores, New Caledonia

Favier, Sylvain; Teitler, Yoram; Golfier, Fabrice; Cathelineau, ‪Michel

doi:10.1016/j.oregeorev.2022.104971

Cited by 8 publications

(8 citation statements)

References 52 publications

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“…Such organization is consistent with the D.P. Model (Figures 6 and 8) and field observations (Favier et al., 2022).…”

Section: Resultssupporting

confidence: 91%

“…9 to 5.5, and (3) an upper zone, entirely composed of goethite, where the pH is buffered at 5.5 (Figures 6a and 6b). Such mineralogical zoning from a phyllosilicate-dominated horizon to an oxide-dominated horizon is consistent with field observations and previous numerical modeling studies (Cathelineau et al, 2016;Domènech et al, 2017;Favier et al, 2022;Myagkiy et al, 2017).…”

Section: Geochemical Evolutionsupporting

confidence: 91%

“…The formation of a lateritic profile is characterized by the propagation of two different weathering fronts: (a) the primary silicates dissolution front in the bedrock and (b) the neo‐formed silicates dissolution front in the saprolite horizon (Cathelineau et al., 2016; Favier et al., 2022). In our study, the primary silicates dissolution front is depicted by the olivine dissolution (Figures 5a, 5b, 5e, and 5f), while the neo‐formed silicates dissolution front is represented by the Mg‐phyllosilicates dissolution (Figures 5i and 5j).…”

Section: Resultsmentioning

confidence: 99%

“…Recent studies highlight the structural control of the weathering front progression (Favier et al., 2022; Iseppi et al., 2018; Jeanpert et al., 2019) as either a drain or a permeability barrier depending on the fractures coating and their orientation to the fluid flow. The impermeable fractures are serpentine (lizardite) filled fractures.…”

Section: Introductionmentioning

confidence: 99%

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Reactive Transport Modeling in Porous Fractured Media: Application to Weathering Processes

Favier,

Teitler,

Golfier

et al. 2024

Water Resources Research

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Complex permeability distribution is frequently encountered in weathered rocks with inherited heterogeneities, such as networks of discontinuities that impact fluid flow and water‐rock interactions. Reactive transport modeling is a powerful tool for analyzing fractured media's chemical weathering dynamics. In this study, two different ways to model the fracture‐matrix interaction were explored. A 1D dual‐porosity simulation of reactive transport is designed to study the global impact of fractures on the weathering progression front, compared with a Single Porosity (S.P.) (unfractured) reference model. Then a 2D discrete model using a Discrete Fracture Matrix (DFM) representation is built to highlight the importance of medium geometry and fracture connectivity on weathering. The relevance of such models was evaluated in the case of weathering processes affecting ultramafic units in New Caledonia. Comparing the average behavior of the dual and S.P. models reveals a similar trend in both global mineralogical evolutions. Yet differences occur when confronting the weathering rates. By extending the weathering over a greater depth, the fractures favor a smoother transition between the saprolite horizon and the oxide ore. Furthermore, a partition of the newly formed phyllosilicates occurs in fractures and matrix: Ni‐phyllosilicates preferentially precipitate in fractures, while Mg‐phyllosilicates remain trapped within the matrix due to differences in residence time and liquid‐to‐solid ratio. The DFM modeling highlights the effect of the connectivity of a complex fracture network on the dissolution‐precipitation processes. Depending on the permeability and geometry, fluid flow is modified, favoring the formation of weathering heterogeneities typically observed on the field.

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“…Such organization is consistent with the D.P. Model (Figures 6 and 8) and field observations (Favier et al., 2022).…”

Section: Resultssupporting

confidence: 91%

Section: Geochemical Evolutionsupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reactive Transport Modeling in Porous Fractured Media: Application to Weathering Processes

Favier,

Teitler,

Golfier

et al. 2024

Water Resources Research

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“…The model consists of the progressive 1D dissolution of a fully saturated 4.5 mlong olivine column by rainwater, followed by a progressive evaporation step. Olivine composition was selected according to probe measurements on fresh olivine: Mg 1.865 Fe 0.127 Ni 0.008 SiO 4 and its initial porosity of 1% was taken from [68]. The initial rainwater composition was taken from [2] (Table 1).…”

Section: Geochemical Modelling Of the Cement Formationmentioning

confidence: 99%

Pseudo-Karst Silicification Related to Late Ni Reworking in New Caledonia

et al. 2023

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Silicification in New Caledonian pseudo-karsts developed on peridotite was assessed using δ18O and δ30Si pairs on quartz cements. The objective was to document the chronology of pseudo-karst development and cementation relative to geomorphic evolution. The latter began at the end of the Eocene with the supergene alteration of peridotites and the subsequent formation of extended lateritic weathering profiles. Neogene uplift favoured the dismantling of these early lateritic profiles and valley deepening. The river incision resulted in (i) the stepping of a series of lateritic paleo-landforms and (ii) the development of a pseudo-karst system with subvertical dissolution pipes preferentially along pre-existing serpentine faults. The local collapse of the pipes formed breccias, which were then cemented by white quartz and Ni-rich talc-like (pimelite). The δ30Si of quartz, ranging between −5‰ and −7‰, are typical of silcretes and close to the minimum values recorded worldwide. The estimated δ18O of −6 to −12‰ for the fluids are lower than those of tropical rainfall typical of present-day and Eocene–Oligocene climates. Evaporation during drier climatic episodes is the main driving force for quartz and pimelite precipitation. The silicification presents similarities with silcretes from Australia, which are considered predominantly middle Miocene in age.

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Slope-specific lateritization of garnet–sillimanite–gneiss cuestas in Matale area, Sri Lanka

Weligepola,

Dissanayake,

Mantilaka

et al. 2024

Int J Earth Sci (Geol Rundsch)

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Multiscale physical–chemical analysis of the impact of fracture networks on weathering: Application to nickel redistribution in the formation of Ni-laterite ores, New Caledonia

Cited by 8 publications

References 52 publications

Reactive Transport Modeling in Porous Fractured Media: Application to Weathering Processes

Reactive Transport Modeling in Porous Fractured Media: Application to Weathering Processes

Pseudo-Karst Silicification Related to Late Ni Reworking in New Caledonia

Slope-specific lateritization of garnet–sillimanite–gneiss cuestas in Matale area, Sri Lanka

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