Special Issue "Serpentine Group Minerals"

A special issue of Minerals (ISSN 2075-163X).

Deadline for manuscript submissions: closed (30 November 2018)

Special Issue Editors

Guest Editor
Dr. Agnès Elmaleh

Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie Sorbonne Universités - UPMC - CNRS 4, Place Jussieu, 75005 Paris, France
Website | E-Mail
Interests: Fe-bearing serpentines; asteroidal water-rock interactions; Fe redox processes; X-ray absorption spectroscopy; magnetometry; XRD
Guest Editor
Dr. Anne-Line Auzende

ISTerre Université Grenoble Alpes - CNRS 1381, rue de la Piscine, 38400 SAINT MARTIN D’HÈRES, France
Website | E-Mail
Interests: subduction; serpentine growth; antigorite; deformation; halogen recycling

Special Issue Information

Dear Colleagues,

Serpentine minerals are widespread on Earth, but also in asteroids, possibly Mars, and other bodies of the solar system. For that reason, serpentinization/deserpentinization processes should have contributed significantly to fluxes of water within the Earth, but also at a larger scale across the solar system, from its early history onward. Serpentinization processes are also believed to have played a key role in early prebiotic organic chemistry, via the production of hydrogen.

Magnesian serpentines are predominant on Earth, and owing to their large pressure and temperature stability field and their abundance, they strongly contribute to fluid-related processes ranging from the oceanic lithosphere down to subduction zones. Our knowledge of their physical properties, which strongly influence the dynamics of the Earth mantle, is constantly improved by experiments and computations down to the atomistic scale. A wealth of studies has addressed the complex role of structural and compositional variations of serpentine group minerals, in particular the effect of the incorporation of Al, Fe2+ and Fe3+ ions on their properties and stability. Turning to extra-terrestrial serpentinization, an even larger range of compositions needs to be considered according to meteorite studies, raising more acutely the question of the conditions of formation and stability of serpentines as a function of their composition.

This Special Issue welcomes contributions on experimentation, modeling and observation from the field down to the nano-scale, helping to apprehend the diversity of structures and crystal-chemistry of serpentine minerals, and to relate them to their environmental conditions of formation and to their role in geodynamic processes and bio-geochemical cycles.

The first round submission deadline is: 31 March 2018

Dr. Agnes Elmaleh
Dr. Anne-Line Auzende
Guest Editors

Manuscript Submission Information

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Keywords

  • terrestrial and extra-terrestrial serpentinization

  • equilibrium conditions; kinetic studies

  • crystal-chemistry

  • structure

  • physical properties

  • dehydration

Published Papers (5 papers)

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Research

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Open AccessArticle Weathering of Ophiolite Remnant and Formation of Ni Laterite in a Strong Uplifted Tectonic Region (Yuanjiang, Southwest China)
Minerals 2019, 9(1), 51; https://doi.org/10.3390/min9010051
Received: 30 November 2018 / Revised: 2 January 2019 / Accepted: 10 January 2019 / Published: 16 January 2019
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Abstract
The Yuanjiang Ni deposit in southwestern margin of the Yunnan Plateau is the only economically important lateritic Ni deposit in China. It contains 21.2 Mt ore with an average grade of 1.05 wt % Ni and has been recognized as the second largest [...] Read more.
The Yuanjiang Ni deposit in southwestern margin of the Yunnan Plateau is the only economically important lateritic Ni deposit in China. It contains 21.2 Mt ore with an average grade of 1.05 wt % Ni and has been recognized as the second largest Ni producer in China following the Jinchuan super-large magmatic Ni–Cu deposit. This Ni deposit is hosted within the lateritic regolith derived from serpentinite within the regional Paleo-Tethyan Ophiolite remnants. Local landscape controls the distribution of the Ni mineralized regolith, and spatially it is characterized by developing on several stepped planation surfaces. Three types of lateritic Ni ores are identified based on Ni-hosting minerals, namely oxide ore, oxide-silicate mixed ore and silicate ore. In the dominant silicate ore, two phyllosilicate minerals (serpentine and talc) are the Ni-host minerals. Their Ni compositions, however, are remarkably different. Serpentine (0.34–1.2 wt % Ni) has a higher Ni concentration than talc (0.18–0.26 wt % Ni), indicating that the serpentine is more significantly enriched in Ni during weathering process compared to talc. This explains why talc veining reduces Ni grade. The geochemical index (S/SAF value = 0.33–0.81, UMIA values = 17–60) indicates that the serpentinite-derived regolith has experienced, at least, weak to moderate lateritization. Based on several lines of paleoclimate evidence, the history of lateritization at Yuanjiang area probably dates to the Oligocene-Miocene boundary and has extended to the present. With a hydrology-controlled lateritization process ongoing, continuous operation of Ni migration from the serpentinite-forming minerals to weathered minerals (goethite and serpentine) gave rise to the development of three types of Ni ore in the regolith. Notably, the formation and preservation of the Yuanjiang lateritic Ni deposit has been strongly impacted by regional multi-staged tectonic uplift during the development of Yunnan Plateau. This active tectonic setting has promoted weathering of serpentinite and supergene Ni enrichment, but is also responsible for its partial erosion. Full article
(This article belongs to the Special Issue Serpentine Group Minerals)
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Open AccessArticle Serpentine–Hisingerite Solid Solution in Altered Ferroan Peridotite and Olivine Gabbro
Minerals 2019, 9(1), 47; https://doi.org/10.3390/min9010047
Received: 20 November 2018 / Revised: 6 January 2019 / Accepted: 11 January 2019 / Published: 15 January 2019
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Abstract
We present microanalyses of secondary phyllosilicates in altered ferroan metaperidotite, containing approximately equal amounts of end-members serpentine ((Mg,Fe2+)3Si2O5(OH)4) and hisingerite (□Fe3+2Si2O5(OH)4·nH2O). These [...] Read more.
We present microanalyses of secondary phyllosilicates in altered ferroan metaperidotite, containing approximately equal amounts of end-members serpentine ((Mg,Fe2+)3Si2O5(OH)4) and hisingerite (□Fe3+2Si2O5(OH)4·nH2O). These analyses suggest that all intermediate compositions can exist stably, a proposal that was heretofore impossible because phyllosilicate with the compositions reported here have not been previously observed. In samples from the Duluth Complex (Minnesota, USA) containing igneous olivine Fa36–44, a continuous range in phyllosilicate compositions is associated with hydrothermal Mg extraction from the system and consequent relative enrichments in Fe2+, Fe3+ (hisingerite), Si, and Mn. Altered ferroan–olivine-bearing samples from the Laramie Complex (Wyoming, USA) show a compositional variability of secondary FeMg–phyllosilicate (e.g., Mg–hisingerite) that is discontinuous and likely the result of differing igneous olivine compositions and local equilibration during alteration. Together, these examples demonstrate that the products of serpentinization of ferroan peridotite include phyllosilicate with iron contents proportionally larger than the reactant olivine, in contrast to the common observation of Mg-enriched serpentine in “traditional” alpine and seafloor serpentinites. To augment and contextualize our analyses, we additionally compiled greenalite and hisingerite analyses from the literature. These data show that greenalite in metamorphosed banded iron formation contains progressively more octahedral-site vacancies (larger apfu of Si) in higher XFe samples, a consequence of both increased hisingerite substitution and structure modulation (sheet inversions). Some high-Si greenalite remains ferroan and seems to be a structural analogue of the highly modulated sheet silicate caryopilite. Using a thermodynamic model of hydrothermal alteration in the Fe–silicate system, we show that the formation of secondary hydrothermal olivine and serpentine–hisingerite solid solutions after primary olivine may be attributed to appropriate values of thermodynamic parameters such as elevated a S i O 2 ( a q ) and decreased a H 2 ( a q ) at low temperatures (~200 °C). Importantly, recent observations of Martian rocks have indicated that they are evolved magmatically like the ferroan peridotites analyzed here, which, in turn, suggests that the processes and phyllosilicate assemblages recorded here are more directly relevant to those occurring on Mars than are traditional terrestrial serpentinites. Full article
(This article belongs to the Special Issue Serpentine Group Minerals)
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Open AccessFeature PaperArticle Intracrystalline Reaction-Induced Cracking in Olivine Evidenced by Hydration and Carbonation Experiments
Minerals 2018, 8(9), 412; https://doi.org/10.3390/min8090412
Received: 3 August 2018 / Revised: 7 September 2018 / Accepted: 14 September 2018 / Published: 18 September 2018
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Abstract
In order to better understand the microtextural changes associated with serpentinization reactions, natural millimeter-sized olivine grains were experimentally reacted with alkaline NaOH and NaHCO3 solutions at a temperature of 200 °C and for durations of 3 to 12 months. During hydration experiments, [...] Read more.
In order to better understand the microtextural changes associated with serpentinization reactions, natural millimeter-sized olivine grains were experimentally reacted with alkaline NaOH and NaHCO3 solutions at a temperature of 200 °C and for durations of 3 to 12 months. During hydration experiments, dissolution and precipitation were intimately correlated in time and space, with reaction products growing in situ, either as layered veins or as nearly continuous surface cover. In contrast, carbonation experiments showed a strong decoupling between both processes leading to essentially delocalized precipitation of the reaction products away from dissolution sites. Textural analyses of the samples using scanning electron microscopy, Raman spectroscopy, and X-ray synchrotron microtomography provided experimental evidence for a cause-and-effect relationship between in situ precipitation and intracrystalline reaction-induced cracking in olivine. Juvenile cracks typically nucleated at the tip of dissolution notches or on diamond-shaped pores filled with reaction products, and propagated through the olivine crystal lattice during the course of the reaction. The occurrence of new cracks at the tip of diamond-shaped pores, but also of tiny subspherical pores lining up along microcracks, indicated that fracturation and porosity networks were mutually driven, making serpentinization an extremely efficient alteration process over time. Alternatively, our data suggested that some form of porosity also developed in absence of fracturation, thus further highlighting the remarkable efficiency and versatility of serpentinization processes. Full article
(This article belongs to the Special Issue Serpentine Group Minerals)
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Review

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Open AccessFeature PaperReview Abyssal Serpentinites: Transporting Halogens from Earth’s Surface to the Deep Mantle
Minerals 2019, 9(1), 61; https://doi.org/10.3390/min9010061
Received: 3 December 2018 / Revised: 16 January 2019 / Accepted: 17 January 2019 / Published: 20 January 2019
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Abstract
Serpentinized oceanic mantle lithosphere is considered an important carrier of water and fluid-mobile elements, including halogens, into subduction zones. Seafloor serpentinite compositions indicate Cl, Br and I are sourced from seawater and sedimentary pore fluids, while F may be derived from hydrothermal fluids. [...] Read more.
Serpentinized oceanic mantle lithosphere is considered an important carrier of water and fluid-mobile elements, including halogens, into subduction zones. Seafloor serpentinite compositions indicate Cl, Br and I are sourced from seawater and sedimentary pore fluids, while F may be derived from hydrothermal fluids. Overall, the heavy halogens are expelled from serpentinites during the lizardite–antigorite transition. Fluorine, on the other hand, appears to be retained or may be introduced from dehydrating sediments and/or igneous rocks during early subduction. Mass balance calculations indicate nearly all subducted F is kept in the subducting slab to ultrahigh-pressure conditions. Despite a loss of Cl, Br and I from serpentinites (and other lithologies) during early subduction, up to 15% of these elements are also retained in the deep slab. Based on a conservative estimate for serpentinite thickness of the metamorphosed slab (500 m), antigorite serpentinites comprise 37% of this residual Cl, 56% of Br and 50% of I, therefore making an important contribution to the transport of these elements to the deep mantle. Full article
(This article belongs to the Special Issue Serpentine Group Minerals)
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Open AccessReview Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites
Minerals 2018, 8(6), 241; https://doi.org/10.3390/min8060241
Received: 30 March 2018 / Revised: 23 May 2018 / Accepted: 31 May 2018 / Published: 5 June 2018
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Abstract
Serpentinites play a key role in controlling fault rheology in a wide range of geodynamic settings, from oceanic and continental rift zones to subduction zones. In this paper, we provide a summary of the most common deformation mechanisms and frictional strengths of serpentine [...] Read more.
Serpentinites play a key role in controlling fault rheology in a wide range of geodynamic settings, from oceanic and continental rift zones to subduction zones. In this paper, we provide a summary of the most common deformation mechanisms and frictional strengths of serpentine minerals and serpentinites. We focus on deformation mechanisms in retrograde serpentinites, which show a progressive evolution from undeformed mesh and bastite pseudomorphic textures to foliated, ribbon-like textures formed by lizardite with strong crystallographic and shape preferred orientations. We also discuss the possible mechanical significance of anastomosing slickenfibre veins containing ultraweak fibrous serpentines or relatively strong splintery antigorite. Our review and new observations indicate that pressure solution and frictional sliding are the most important deformation mechanisms in retrograde serpentinite, and that they are frictionally weak (μ ~0.3). The mineralogical and microstructural evolution of retrograde serpentinites during shearing suggests that a further reduction of the friction coefficient to μ of 0.15 or less may occur during deformation, resulting in a sort of continuous feedback weakening mechanism. Full article
(This article belongs to the Special Issue Serpentine Group Minerals)
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