| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 5783083 | Geochimica et Cosmochimica Acta | 2017 | 27 Pages |
Abstract
Eleven inverse isochron ages from total fusion and three from stepwise heating analyses fit the age model. Four experiments resulted in older inverse isochron ages that do not concur with the model within 2Ï uncertainties and that deviate from 1Â ka to 17Â ka minimum. C- and R-type zoning are interpreted as representing growth in magma chamber cupolas, as wall mushes, or in narrow conduits. Persistent compositions of PO-type crystals and abundant surfaces recording dissolution features correspond to formation within a magma chamber. C-type zoning and R-type zoning have revealed an irregular incorporation of melt and fluid inclusions. These two types of zoning in feldspar are interpreted as preferentially contributing either heterogeneously distributed excess 40Ar or inherited 40Ar to the deviating 40Ar/39Ar ages that are discussed in this study.
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Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Jonathan Franz Engelhardt, Masafumi Sudo, Mona Stockhecke, Roland Oberhänsli,