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Petrological significance of prograde homogenization of growth zoning in garnet: an example from the Llano Uplift
Author(s) -
CARLSON W.,
SCHWARZE E.
Publication year - 1997
Publication title -
journal of metamorphic geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.639
H-Index - 114
eISSN - 1525-1314
pISSN - 0263-4929
DOI - 10.1111/j.1525-1314.1997.tb00640.x
Subject(s) - metamorphism , geology , granulite , metamorphic facies , metamorphic rock , facies , geochemistry , proterozoic , zoning , tectonics , petrology , geomorphology , paleontology , structural basin , political science , law
In the Llano Uplift of central Texas (USA), prograde homogenization of garnet growth zoning took place during moderate‐to high‐pressure dynamothermal metamorphism over a narrow temperature range near the transition from the amphibolite to the granulite facies. This subtle record of early dynamothermal metamorphism survived subsequent static metamorphism at low pressures in the middle‐amphibolite facies, despite the destruction of most high‐pressure mineral assemblages that originated in the early metamorphic episode. Geographically systematic variations in the degree of homogenization indicate that the uplift as a whole underwent high‐pressure metamorphism, in accord with emerging tectonic models for the mid‐Proterozoic evolution of the southern margin of the North American continent.