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 - 1994/1/1
Y1 - 1994/1/1
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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U2 - 10.1130/0016-7606(1994)106<0942:ACOMFI>2.3.CO;2
DO - 10.1130/0016-7606(1994)106<0942:ACOMFI>2.3.CO;2
M3 - Article
AN - SCOPUS:84874962500
SN - 0016-7606
VL - 106
SP - 942
EP - 951
JO - Bulletin of the Geological Society of America
JF - Bulletin of the Geological Society of America
IS - 7
ER -