Constraints on anthophyllite formation in thermally metamorphosed peridotites from southwestern Japan

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Anthophyllite or another species of Mg-amphibole commonly occurs in an intervening zone between the higher grade orthopyroxene zone and lower grade talc zone in progressively metamorphosed peridotites. However, the anthophyllite zone is absent in some of the thermally metamorphosed peridotite complexes in SW Japan despite the existence of the other zones. A comparative study presented here reveals similarities in rock composition and metamorphic pressure-temperature conditions at high-grade zones between the metaperidotite complexes, and differences in the following respects. The metaperidotite complex that contains an anthophyllite zone has less abundant magnetite and olivine that is more homogeneous than the complex where the anthophyllite zone is absent. It is likely that the degree of cation diffusion in olivine crystals depends on duration of heat retention in metaperidotites during thermal metamorphism, which is supported by the variation in mineralogy of intrusive rocks and pelitic hornfelses surrounding the metaperidotites, and by calculations based on a simplified model of thermal conduction. The long duration of heat retention looks to be a necessary condition for the formation of anthophyllite crystals, which have a sluggish nucleation rate. In addition, the circulation of reducing fluids during prolonged metamorphism likely promoted the decomposition of magnetite and the growth of anthophyllite, into which iron is preferentially distributed. This study cautions about kinetic controls and redox conditions for anthophyllite formation in metaperidotites.

Original languageEnglish
Pages (from-to)385-398
Number of pages14
JournalJournal of Metamorphic Geology
Volume29
Issue number4
DOIs
Publication statusPublished - May 2011

Fingerprint

anthophyllite
Ferrosoferric Oxide
Amphibole Asbestos
magnetite
Rocks
olivine
metamorphism
Talc
Crystals
crystal
Mineralogy
talc
redox conditions
Cations
orthopyroxene
peridotite
rock
amphibole
nucleation
Nucleation

Keywords

  • Anthophyllite
  • Crystallization kinetics
  • Peridotite
  • Serpentinite
  • Thermal metamorphism

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geology

Cite this

Constraints on anthophyllite formation in thermally metamorphosed peridotites from southwestern Japan. / Nozaka, Toshio.

In: Journal of Metamorphic Geology, Vol. 29, No. 4, 05.2011, p. 385-398.

Research output: Contribution to journalArticle

@article{e8ca3d594e4b4ed1b91e072a00846184,
title = "Constraints on anthophyllite formation in thermally metamorphosed peridotites from southwestern Japan",
abstract = "Anthophyllite or another species of Mg-amphibole commonly occurs in an intervening zone between the higher grade orthopyroxene zone and lower grade talc zone in progressively metamorphosed peridotites. However, the anthophyllite zone is absent in some of the thermally metamorphosed peridotite complexes in SW Japan despite the existence of the other zones. A comparative study presented here reveals similarities in rock composition and metamorphic pressure-temperature conditions at high-grade zones between the metaperidotite complexes, and differences in the following respects. The metaperidotite complex that contains an anthophyllite zone has less abundant magnetite and olivine that is more homogeneous than the complex where the anthophyllite zone is absent. It is likely that the degree of cation diffusion in olivine crystals depends on duration of heat retention in metaperidotites during thermal metamorphism, which is supported by the variation in mineralogy of intrusive rocks and pelitic hornfelses surrounding the metaperidotites, and by calculations based on a simplified model of thermal conduction. The long duration of heat retention looks to be a necessary condition for the formation of anthophyllite crystals, which have a sluggish nucleation rate. In addition, the circulation of reducing fluids during prolonged metamorphism likely promoted the decomposition of magnetite and the growth of anthophyllite, into which iron is preferentially distributed. This study cautions about kinetic controls and redox conditions for anthophyllite formation in metaperidotites.",
keywords = "Anthophyllite, Crystallization kinetics, Peridotite, Serpentinite, Thermal metamorphism",
author = "Toshio Nozaka",
year = "2011",
month = "5",
doi = "10.1111/j.1525-1314.2010.00921.x",
language = "English",
volume = "29",
pages = "385--398",
journal = "Journal of Metamorphic Geology",
issn = "0263-4929",
publisher = "Wiley-Blackwell",
number = "4",

}

TY - JOUR

T1 - Constraints on anthophyllite formation in thermally metamorphosed peridotites from southwestern Japan

AU - Nozaka, Toshio

PY - 2011/5

Y1 - 2011/5

N2 - Anthophyllite or another species of Mg-amphibole commonly occurs in an intervening zone between the higher grade orthopyroxene zone and lower grade talc zone in progressively metamorphosed peridotites. However, the anthophyllite zone is absent in some of the thermally metamorphosed peridotite complexes in SW Japan despite the existence of the other zones. A comparative study presented here reveals similarities in rock composition and metamorphic pressure-temperature conditions at high-grade zones between the metaperidotite complexes, and differences in the following respects. The metaperidotite complex that contains an anthophyllite zone has less abundant magnetite and olivine that is more homogeneous than the complex where the anthophyllite zone is absent. It is likely that the degree of cation diffusion in olivine crystals depends on duration of heat retention in metaperidotites during thermal metamorphism, which is supported by the variation in mineralogy of intrusive rocks and pelitic hornfelses surrounding the metaperidotites, and by calculations based on a simplified model of thermal conduction. The long duration of heat retention looks to be a necessary condition for the formation of anthophyllite crystals, which have a sluggish nucleation rate. In addition, the circulation of reducing fluids during prolonged metamorphism likely promoted the decomposition of magnetite and the growth of anthophyllite, into which iron is preferentially distributed. This study cautions about kinetic controls and redox conditions for anthophyllite formation in metaperidotites.

AB - Anthophyllite or another species of Mg-amphibole commonly occurs in an intervening zone between the higher grade orthopyroxene zone and lower grade talc zone in progressively metamorphosed peridotites. However, the anthophyllite zone is absent in some of the thermally metamorphosed peridotite complexes in SW Japan despite the existence of the other zones. A comparative study presented here reveals similarities in rock composition and metamorphic pressure-temperature conditions at high-grade zones between the metaperidotite complexes, and differences in the following respects. The metaperidotite complex that contains an anthophyllite zone has less abundant magnetite and olivine that is more homogeneous than the complex where the anthophyllite zone is absent. It is likely that the degree of cation diffusion in olivine crystals depends on duration of heat retention in metaperidotites during thermal metamorphism, which is supported by the variation in mineralogy of intrusive rocks and pelitic hornfelses surrounding the metaperidotites, and by calculations based on a simplified model of thermal conduction. The long duration of heat retention looks to be a necessary condition for the formation of anthophyllite crystals, which have a sluggish nucleation rate. In addition, the circulation of reducing fluids during prolonged metamorphism likely promoted the decomposition of magnetite and the growth of anthophyllite, into which iron is preferentially distributed. This study cautions about kinetic controls and redox conditions for anthophyllite formation in metaperidotites.

KW - Anthophyllite

KW - Crystallization kinetics

KW - Peridotite

KW - Serpentinite

KW - Thermal metamorphism

UR - http://www.scopus.com/inward/record.url?scp=79953285157&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=79953285157&partnerID=8YFLogxK

U2 - 10.1111/j.1525-1314.2010.00921.x

DO - 10.1111/j.1525-1314.2010.00921.x

M3 - Article

AN - SCOPUS:79953285157

VL - 29

SP - 385

EP - 398

JO - Journal of Metamorphic Geology

JF - Journal of Metamorphic Geology

SN - 0263-4929

IS - 4

ER -