Development of inverted metamorphic isograds in the western metamorphic belt, Juneau, Alaska
An inverted metamorphic gradient is preserved in the western metamorphic belt near Juneau, Alaska. Detailed mapping of pelitic single-mineral isograds, systematic changes in mineral assemblages, and silicate geothermometry indicate that thermal peak metamorphic conditions increase structurally upward over a distance of about 8 km. Silicate geobarometry suggests that the thermal peak metamorphism occurred under pressures of 9-11 kbar. Our preferred interpretation of the cause of the inverted gradient is that it formed during compression of a thickened wedge of relatively wet and cool rocks in response to heat flow associated with the formation and emplacement of tonalite sill magma. -from Authors
Citation Information
Publication Year | 1991 |
---|---|
Title | Development of inverted metamorphic isograds in the western metamorphic belt, Juneau, Alaska |
Authors | G. R. Himmelberg, D. A. Brew, A. B. Ford |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Journal of Metamorphic Geology |
Index ID | 70016798 |
Record Source | USGS Publications Warehouse |