The internal deformation of the Peridotite Nappe of New Caledonia: A structural study of serpentine-bearing faults and shear zones in the Koniambo Massif

Quesnel, Benoît; Gautier, Pierre; Cathelineau, ‪Michel; Boulvais, Philippe; Couteau, Clément; Drouillet, Maxime

doi:10.1016/j.jsg.2016.02.006

Cited by 27 publications

(30 citation statements)

References 41 publications

(71 reference statements)

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“…The superstructure periodicity (corresponding to the wavelength of the antigorite corrugated crystal structure) obtained in the different veins was unrelated to regional and contact metamorphic grade, unlike what is reported for antigorite-bearing massive serpentinites (e.g., [78]). More recently, antigorite veins have been described by Groppo et al [75] and Quesnel et al [76], and similar occurrences may be found in asbestos-related studies, where the term "fibrous antigorite" is typically used. Antigorite crystals are highly elongated, parallel to the [010] atg axis.…”

Section: The Puzzling Case Of Antigorite Splintery Veinssupporting

confidence: 60%

“…According to these authors, the main serpentine veins found in natural faults and shear zones are (formed from the first to last stages of serpentinite evolution): isolated sigmoidal chrysotile veins (V2 in their classification); crack-seal veins formed by variable mixtures of protoserpentine, chrysotile and polygonal serpentine fibres (V3; see also [53] for this kind of vein); and polyhedral serpentine/lizardite veins (V4). Together with these varieties, we also remark that splintery antigorite slickenfibre veins are extremely widespread and that, quite surprisingly, they have remained relatively poorly described in recent studies [69,75,76].…”

Section: The Role Of Serpentine Veinsmentioning

confidence: 57%

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Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites

et al. 2018

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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.

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Section: The Puzzling Case Of Antigorite Splintery Veinssupporting

confidence: 60%

Section: The Role Of Serpentine Veinsmentioning

confidence: 57%

Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites

et al. 2018

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“…The Raman spectra of polygonal serpentine were first reported by Lemaire (1999) and then Auzende et al (2004) who both identified a unique peak at 3,697 cm −1 with a shoulder at 3,689 cm −1 and a broad secondary peak at 3,646 cm −1 . These publications have since served as a reference for identification of polygonal serpentine on the basis of its Raman spectrum . However, there remains some degree of uncertainty with regard to the Raman signal of polygonal serpentine.…”

Section: Introductionmentioning

confidence: 98%

“…However, there remains some degree of uncertainty with regard to the Raman signal of polygonal serpentine. Specifically, some authors have been unable to differentiate polygonal serpentine from chrysotile or a mixture of lizardite and chrysotile …”

Section: Introductionmentioning

confidence: 99%

Distinguishing the Raman spectrum of polygonal serpentine

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Rooney

Viti

et al. 2018

J Raman Spectroscopy

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Positively identifying serpentine mineral types is important for a wide range of disciplines in the Earth sciences and health sciences. Although Raman spectroscopy has been widely applied as a tool to distinguish four of the main serpentine minerals (i.e., antigorite, lizardite, chrysotile, and polygonal serpentine), some uncertainty remains as to whether all four varieties have unique Raman spectra. In this paper, submicron Raman spectroscopy mapping was performed directly on electron‐transparent regions of serpentine samples that were unambiguously identified by transmission electron microscopy (TEM). The increased spatial resolution of the Raman mapping technique (~370 nm), combined with the detailed characterization provided by TEM, indicates that polygonal serpentine has the same Raman spectrum as lizardite and therefore cannot be spectrally distinguished from lizardite. Furthermore, the Raman spectral profile that has previously been reported as unique to polygonal serpentine is likely to represent a mixture of chrysotile and polygonal serpentine/lizardite. To positively discriminate between lizardite and polygonal serpentine requires TEM investigation.

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“…Recently, the deformation associated with serpentinization and carbonation of the peridotites has been characterized in the Koniambo Massif, one of the klippes of the Peridotite Nappe in northern New Caledonia [ Quesnel et al ., , ]. Here we summarize the results of this analysis and present additional observations made in other klippes.…”

Section: Introductionmentioning

confidence: 99%

The emplacement of the Peridotite Nappe of New Caledonia and its bearing on the tectonics of obduction

2016

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The Peridotite Nappe of New Caledonia is one of the few ophiolites worldwide that escaped collisional orogeny after obduction. Here we describe the deformation associated with serpentinization in two klippes of the nappe in northwestern New Caledonia. The klippes are flat lying and involve S/SW vergent reverse‐slip shear zones which are true compressional structures in origin. Further northeast, the nappe is folded in association with the development of a steep schistosity in low‐grade metasediments. This difference in structural style indicates that the Peridotite Nappe experienced compression at greater depths toward its root zone, suggesting a “push from the rear” mechanism of emplacement. This supports the view that the nappe has been emplaced through horizontal contraction sustained by plate convergence. We establish a crustal‐scale cross section at the end of the obduction event, before Neogene extension. This involves a large fold nappe of high‐pressure rocks bounded from below by a major thrust. Furthermore, we show that obduction in New Caledonia occurred through dextral oblique convergence. Oblique convergence probably resulted from the initial obliquity between the subduction trench and the continental ribbon that became incorporated in it. This obliquity can solve the paradox of the Peridotite Nappe seemingly being emplaced at the same time the high‐pressure rocks were exhumed. Oblique convergence together with focused erosional denudation on the northeastern flank of the island led to exhumation of the metamorphic rocks in a steep fold nappe rising through the rear part of the orogen.

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The internal deformation of the Peridotite Nappe of New Caledonia: A structural study of serpentine-bearing faults and shear zones in the Koniambo Massif

Cited by 27 publications

References 41 publications

Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites

Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites

Distinguishing the Raman spectrum of polygonal serpentine

The emplacement of the Peridotite Nappe of New Caledonia and its bearing on the tectonics of obduction

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