Argon composition of metamorphic fluids: implications for                          40                         Ar/                          39                         Ar geochronology

R. J. Cumbest; E. L. Johnson; Tullis C. Onstott

doi:10.1130/0016-7606(1994)106<0942:ACOMFI>2.3.CO;2

Argon composition of metamorphic fluids: implications for ⁴⁰ Ar/ ³⁹ Ar geochronology

R. J. Cumbest
, E. L. Johnson
, Tullis C. Onstott

Research output: Contribution to journal › Article › peer-review

57 Scopus citations

Abstract

The concentration and isotopic composition of argon trapped in fluid inclusions within a mylonitic amphibolite were determined. Such information provides constraints on the origin of metamorphic fluids. In this study, fluid in inclusions formed during ductile deformation was probably derived locally from Paleozoic, Caledonian sequences, whereas brines, emplaced in cross-cutting fractures, were derived from Proterozoic footwall rocks several kilometers from the mylonite, By utilizing ³⁸ Ar _Cl to correct for "excess ⁴⁰ Ar,' we estimate a 370 Ma closure age for the amphibole, which is distinctly younger than the 440-480 Ma plateau ages indicated by step-heating spectra. -Authors

Original language	English (US)
Pages (from-to)	942-951
Number of pages	10
Journal	Geological Society of America Bulletin
Volume	106
Issue number	7
DOIs	https://doi.org/10.1130/0016-7606(1994)106<0942:ACOMFI>2.3.CO;2
State	Published - 1994

All Science Journal Classification (ASJC) codes

Geology

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10.1130/0016-7606(1994)106<0942:ACOMFI>2.3.CO;2

Cite this

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title = "Argon composition of metamorphic fluids: implications for 40 Ar/ 39 Ar geochronology",

abstract = " The concentration and isotopic composition of argon trapped in fluid inclusions within a mylonitic amphibolite were determined. Such information provides constraints on the origin of metamorphic fluids. In this study, fluid in inclusions formed during ductile deformation was probably derived locally from Paleozoic, Caledonian sequences, whereas brines, emplaced in cross-cutting fractures, were derived from Proterozoic footwall rocks several kilometers from the mylonite, By utilizing 38 Ar Cl to correct for {"}excess 40 Ar,' we estimate a 370 Ma closure age for the amphibole, which is distinctly younger than the 440-480 Ma plateau ages indicated by step-heating spectra. -Authors ",

author = "Cumbest, \{R. J.\} and Johnson, \{E. L.\} and Onstott, \{Tullis C.\}",

year = "1994",

doi = "10.1130/0016-7606(1994)106<0942:ACOMFI>2.3.CO;2",

language = "English (US)",

volume = "106",

pages = "942--951",

journal = "Geological Society of America Bulletin",

issn = "0016-7606",

publisher = "Geological Society of America",

number = "7",

}

Argon composition of metamorphic fluids: implications for ⁴⁰ Ar/ ³⁹ Ar geochronology. / Cumbest, R. J.; Johnson, E. L.; Onstott, Tullis C.
In: Geological Society of America Bulletin, Vol. 106, No. 7, 1994, p. 942-951.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Argon composition of metamorphic fluids

T2 - implications for 40 Ar/ 39 Ar geochronology

AU - Cumbest, R. J.

AU - Johnson, E. L.

AU - Onstott, Tullis C.

PY - 1994

Y1 - 1994

N2 - The concentration and isotopic composition of argon trapped in fluid inclusions within a mylonitic amphibolite were determined. Such information provides constraints on the origin of metamorphic fluids. In this study, fluid in inclusions formed during ductile deformation was probably derived locally from Paleozoic, Caledonian sequences, whereas brines, emplaced in cross-cutting fractures, were derived from Proterozoic footwall rocks several kilometers from the mylonite, By utilizing 38 Ar Cl to correct for "excess 40 Ar,' we estimate a 370 Ma closure age for the amphibole, which is distinctly younger than the 440-480 Ma plateau ages indicated by step-heating spectra. -Authors

AB - The concentration and isotopic composition of argon trapped in fluid inclusions within a mylonitic amphibolite were determined. Such information provides constraints on the origin of metamorphic fluids. In this study, fluid in inclusions formed during ductile deformation was probably derived locally from Paleozoic, Caledonian sequences, whereas brines, emplaced in cross-cutting fractures, were derived from Proterozoic footwall rocks several kilometers from the mylonite, By utilizing 38 Ar Cl to correct for "excess 40 Ar,' we estimate a 370 Ma closure age for the amphibole, which is distinctly younger than the 440-480 Ma plateau ages indicated by step-heating spectra. -Authors

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M3 - Article

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SN - 0016-7606

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JO - Geological Society of America Bulletin

JF - Geological Society of America Bulletin

IS - 7

ER -

Argon composition of metamorphic fluids: implications for ⁴⁰ Ar/ ³⁹ Ar geochronology

Abstract

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