On the role of melt-rock reaction in mantle shear zone formation in the Othris Peridotite Massif (Greece)

Dijkstra, Arjan H.; Drury, M. R.; Vissers, R. L. M.; Newman, Joseph W.

doi:10.1016/s0191-8141(01)00142-0

Cited by 91 publications

(114 citation statements)

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“…Recent textural and geochemical investigations proposed that refertilization by basaltic or refractory melts is also an important process in abyssal peridotites (Hellebrand et al 2002;Kelemen et al 2004;Seyler et al 2007), which have been conventionally interpreted as simple residues of partial melting (Johnson et al 1990;Johnson and Dick 1992). Reactive porous flow and refertilization are two important processes that are able to deeply modify textures, mineral modes and chemical compositions of peridotites ( Van der Wal and Bodinier 1996;Bedini et al 1997;Godard et al 2000;Dijkstra et al 2002;Müntener and Piccardo 2003;Piccardo et al 2004bPiccardo et al , 2007a. The rocks do not reveal a substantial Ce/Yb fractionation, which is consistent with a refertilization hypothesis.…”

Section: Whole Rock Trace Element Variabilitymentioning

confidence: 99%

“…Van der Wal and Bodinier 1996;Godard et al 2000;Lenoir et al 2000Lenoir et al , 2001Dijkstra et al 2002;Piccardo et al 2007a;Bodinier et al 2008). For example, in Oman, the high-temperature mantle deformation and the distance from the Moho are correlated with the chemical composition of peridotite (Godard et al 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Textures and mineral chemistry of many plagioclase peridotites are inconsistent with a residual origin and are interpreted as the product of impregnation with melt (Dijkstra et al 2002;Müntener and Piccardo 2003). Substantial amounts of clinopyroxene, orthopyroxene, olivine and Al-phases (spinel, plagioclase) reacted with, and partially recrystallized from migrating melt (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Permanent grain size reduction might occur in melt-and H 2 O-free peridotites (Warren and Hirth 2006), but also in peridotites that were affected by melt-rock reaction (e.g. Dijkstra et al 2002). Magmatic crystallization and shearing are frequently associated and suggest that fault systems and shear zones act as conduits for ascending magma (e.g.…”

Section: Introductionmentioning

confidence: 99%

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The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation

Kaczmarek

Müntener

2010

Contrib Mineral Petrol

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In this paper we present new data on the spatial variability of peridotite composition across a kilometerscale mantle shear zone within the Lanzo massif (Western Alps, Italy). The shear zone separates the central from the northern part of the massif. Plagioclase peridotite shows gradually increasing deformation towards the shear zone, from porphyroclastic to mylonitic textures in the central body, while the northern body is composed of porphyroclastic rocks. The peridotite displays a large range of compositions, from fertile peridotite to refractory harzburgite and dunite. Deformed peridotites (proto-mylonite and mylonites) tend to be compositionally more homogeneous and fertile than weakly deformed peridotites. The composition of most plagioclase peridotites show rather high and constant (Ce/Yb) N ratios, and Yb N that cannot be explained by any simple melting model. Instead, refertilization modeling, consisting of melt increments from spinel peridotite sources, particularly with E-MORB melt, reasonably reproduces the plagioclase peridotite whole rock composition. Combined with constraints from Ce-Nb and Ce-Th systematics, we speculate that peridotites such as those from Lanzo record pervasive refertilization processes in the thermal boundary layer. In this scenario, mantle shear zones might act as important areas of melt focusing in the upper mantle that separates the thermal boundary layer from the conductively cooled mantle.

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Section: Whole Rock Trace Element Variabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation

Kaczmarek

Müntener

2010

Contrib Mineral Petrol

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“…The strain increases to the southeast where the harzburgites grade into plagioclaseperidotites, relatively rich in clinopyroxene porphyroclast, which recrystallized to pargasitic amphibole. The intense deformation recorded in these rocks resulted in These plagioclase peridotites, which are also widespread in most of the western ultramafic massifs are not primary mantle lherzolites for two reasons: their plagioclase content is highly inhomogeneous, expressed by a mineralogical layering ranging from dunites to troctolites (Figure 3(b)-(d)); and spinel grains do not exhibit the normal irregular morphologies and the close spatial association with pyroxenes typical of pristine lherzolites (Boudier 1976;Nicolas 1989;Dijkstra et al 2001Dijkstra et al , 2002, but rather show an idiomorphic shape, typical of the residual dunites, and a random distribution in the rock. We interpret these plagioclase-peridotites as an artifact of extreme deformation of dunites and harzburgites impregnated by basaltic liquids and intruded by gabbroic veins and sills.…”

Section: Krabbi Massif (Figure 7)mentioning

confidence: 99%

Structure and tectonics of lower crustal and upper mantle rocks in the Jurassic Mirdita ophiolites, Albania

Meshi

Boudier

Nicolas

et al. 2009

International Geology Review

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The Jurassic Mirdita ophiolite crops out in the western branch of the HellenideDinaride ophiolite belt in the Balkan Peninsula; it represents a remnant of the Tethyan oceanic lithosphere developed between the Apulian and Pelagonian microcontinents. Emplaced during the Cretaceous on the western margin of Pelagonia, the Mirdita ophiolite was involved in southwestward thrusting of the Hellenide-Dinaride tectonic units during the Eocene alpine tectonics. It was little affected, however, by these alpine events as marked by nearly horizontal Cretaceous limestone deposits overlying the ophiolite. A continuous section of Middle Jurassic oceanic crust, including thin gabbros, a N-S-trending sheeted dike complex, and extrusive rocks, is exposed in the central part of the ophiolite and thickens eastward within a regional, N-S-trending synform. Peridotite massifs exposed along the western and eastern edges of this synform show major structural and petrological differences. The eastern ultramafic domain has a harzburgitic mantle exhibiting a high-temperature asthenospheric foliation dipping steeply to moderately to the west. Major chromite deposits are restricted to these eastern ultramafic massifs. The western ultramafic domain has a zoned mantle, with asthenospheric harzburgite exposed at its western margin, progressively replaced eastward by plagioclase-peridotites that were highly strained at low temperatures, and that are bounded by amphibole-peridotites along with crustal rocks. The occurrence of plagioclase is ascribed to melt impregnation processes that occurred immediately before or during intense lithospheric deformation. The gabbros in the eastern massifs are thicker (1-2 km and layered, whereas they are highly thin and discontinuous in the western massifs. Mantle peridotites of the western massifs locally are in direct contact with the overlying diabase and volcanic rocks along ductile shear zones. Development of epidote-amphibolite facies metamorphism in upper-crustal rocks was produced by hydrothermal alteration in the oceanic realm, and was intense and widespread in the western domain. The Mirdita ophiolite likely originated in a short-lived, narrow ocean basin, which was closed during the Middle Jurassic by eastward overthrusting of the western domain, and westward subduction of the eastern domain. This constrictional phase was followed by dextral oblique convergence between the Pelagonian and Apulian microcontinents. This model implies a parautochtonous origin of the Mirdita ophiolite between these two microcontinents.

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Grain‐size sensitive rheology of orthopyroxene

Bruijn

Skemer

2014

Geophysical Research Letters

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The grain-size sensitive rheology of orthopyroxene is investigated using data from rheological and microstructural studies. A deformation mechanism map is constructed assuming that orthopyroxene deforms by two independent mechanisms: dislocation creep and diffusion creep. The field boundary between these mechanisms is defined using two approaches. First, experimental data from Lawlis (1998), which show a deviation from non-linear power law behavior at low stresses, are used to prescribe the location of the field boundary. Second, a new orthopyroxene grain-size piezometer is used as a microstructural constraint to the field boundary. At constant temperature, both approaches yield sub-parallel field boundaries, separated in grain size by a factor of only 2-5. Extrapolating to lithospheric conditions, the deformation mechanism transition occurs at a grain size of~150-500 μm, consistent with observations from nature. As the transition from dislocation to diffusion creep may promote shear localization, grain-size reduction of orthopyroxene may play a prominent role in plate-boundary deformation. Methods Deformation Mechanism MapsRocks at high temperature and pressure may deform by several different ductile deformation mechanisms. Deformation mechanism maps show the range of conditions where each mechanism exerts primary control BRUIJN AND SKEMER

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On the role of melt-rock reaction in mantle shear zone formation in the Othris Peridotite Massif (Greece)

Cited by 91 publications

References 59 publications

The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation

The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation

Structure and tectonics of lower crustal and upper mantle rocks in the Jurassic Mirdita ophiolites, Albania

Grain‐size sensitive rheology of orthopyroxene

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