Coesite and pure pyrope in high-grade blueschists of the Western Alps: a first record and some consequences

Chopin, Christian

doi:10.1007/bf00381838

Cited by 1,220 publications

(634 citation statements)

References 36 publications

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“…[13] The Dora Maira Massif was the first ultra-high pressure (UHP) metamorphic massif with P > 2.8 GPa in which coesite was reported [Chopin, 1984]. These UHP rocks formed as a result of continental lithosphere subduction to depths up to 100 km [Hacker and Peacock, 1994].…”

Section: Geology Of the Sampling Localitiesmentioning

confidence: 99%

Magnetic properties of fault pseudotachylytes in granites

Ferré¹,

Geissman²,

Zechmeister³

2012

J. Geophys. Res.

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[1] We investigate the petrographic, geochemical and magnetic properties of fault pseudotachylytes formed by frictional melting in granitic rocks from Southern California, the Italian Alps and Kyushyu, Japan. The main magnetic remanence carriers are mixtures of grain sizes of fine grained magnetite. These ferrimagnetic grains record a stable, multicomponent magnetization that consists of one or more of the following: coseismic thermal remanent magnetization, coseismic lightning isothermal remanent magnetization and post-seismic chemical remanent magnetization. Fault pseudotachylytes from the three localities display contrasting magnetic properties, which suggests that oxygen fugacity and host rock composition ultimately control the magnetic assemblage.

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Section: Geology Of the Sampling Localitiesmentioning

confidence: 99%

Magnetic properties of fault pseudotachylytes in granites

Ferré¹,

Geissman²,

Zechmeister³

2012

J. Geophys. Res.

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“…Such small-scale processes may also be poorly resolved in these models as a result of the finite element size. A final restriction on the models is that the maximum depth of accretion is limited to the vertical depth of the model domain (nominally 60 kin), so that accretion of units whose ultrahigh-pressure signatures indicate that they have been subducted to depths of 90 km or more [Chopin, 1984] is not investigated.…”

Section: Model Limitationsmentioning

confidence: 99%

Geodynamic models of crustal‐scale episodic tectonic accretion and underplating in subduction zones

Ellis¹,

Beaumont²,

Pfiffner³

1999

J. Geophys. Res.

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“…Since the first findings of coesite, the high-pressure SiO 2 polymorph in crustal rocks (Chopin, 1984;Smith, 1984), it has become a very powerful mineral-indicator of ultrahigh-pressure metamorphism. Unlike diamonds, the presence of only one coesite inclusion undoubtedly provides evidence for an UHPM origin of the host mineral (Korsakov et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Is quartz a potential indicator of ultrahigh-pressure metamorphism? Laser Raman spectroscopy of quartz inclusions in ultrahigh-pressure garnets

Korsakov¹,

Perraki²,

Zhukov³

et al. 2010

ejm

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Laser Raman microspectroscopy was applied to quartz inclusions in coesite-and diamond-grade metapelites from the Kokchetav ultrahigh-pressure metamorphic (UHPM) complex, Northern Kazakhstan, and diamond-grade eclogite xenoliths from the Mir kimberlite pipe, Yakutiya, Russia to assess the quantitative correlation between the Raman frequency shift and metamorphic pressure. Quartz crystals sealed in garnets have a higher frequency shift than those in the matrix. Residual pressures retained by quartz inclusions depend on the metamorphic history of the garnet host. The Raman frequency shift of quartz inclusions in garnet from coesite-grade and diamond-grade metamorphic rocks shows no systematic change with increasing peak metamorphic pressures. The highest shifts of the main Raman bands of quartz were documented for monocrystalline quartz inclusions in garnets from a diamond-grade eclogite xenolith. Calibrations based on experimental work suggest that the measured Raman frequency shifts signify residual pressures of 0.1-0.6 GPa for quartz inclusions from coesite-grade metapelites from Kokchetav, 0.1-0.3 GPa for quartz inclusions from diamond-grade metapelites from Kokchetav, and 1.0-1.2 GPa for quartz inclusions from the diamondgrade eclogite xenoliths from the Mir kimberlite pipe. Normal stresses and internal (residual) pressures of quartz inclusions in garnet were numerically simulated with a 3-shell elastic model. Estimated values of residual pressures are inconsistent with the residual pressures estimated from the frequency shifts. Residual pressure slightly depends on P-T conditions at peak metamorphic stage. Laser Raman microspectroscopic analysis of quartz is a potentially powerful method for recovering an ultrahigh pressure metamorphic event. Monocrystalline quartz inclusions yielding a residual pressure greater than 2.5 GPa might indicate the presence of a former coesite.

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Coesite and pure pyrope in high-grade blueschists of the Western Alps: a first record and some consequences

Cited by 1,220 publications

References 36 publications

Magnetic properties of fault pseudotachylytes in granites

Magnetic properties of fault pseudotachylytes in granites

Geodynamic models of crustal‐scale episodic tectonic accretion and underplating in subduction zones

Is quartz a potential indicator of ultrahigh-pressure metamorphism? Laser Raman spectroscopy of quartz inclusions in ultrahigh-pressure garnets

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