isograd


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isograd

[′ī·sə‚grad]
(geology)
A line on a map joining those rocks comprising the same metamorphic grade.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Coexisting chloritoid and staurolite and the staurolite-chlorite isograd from the Agnew Lake area, Ontario, Canada.
Rios and Takasu (1999) consider that at the staurolite isograd, [X.sub.grs] increases with increasing temperature, which is difficult to determine taking into account that garnet tends to be resorbed back to higher [X.sub.grs] concentrations as staurolite grows.
However, this reaction, which promotes the disappearance of staurolite also coincides with the appearance of kyanite (at pressure greater than about 2.5 kbar), and if we were to encounter this reaction in the field, it could be used to define the kyanite isograd.
The sharp offset in the andalusite-in isograd assists mapping the stratigraphic contact within the metamorphic aureole.
Metamorphic reactions and isograds related to this intrusion were documented by Jamieson et al.
Folding of metamorphic isograd surfaces above a footwall ramp would account for the observed trends.
DELINEATING THE EFFECTS OF LATE PALEOZOIC DEFORMATION OF MIDDLE PALEOZOIC METAMORPHIC ISOGRADS WITH GEOTHERMOBAROMETRY.