40Ar/39Ar ages from the Selawik A-2, A-3 and A-4 and Candle B-5 quadrangles, Alaska
Description
40Ar/39Ar data from seven plutonic samples and one metamorphic sample collected during mineral assessment studies in 1991 show that various rock units in the Selawik Hills plutonic complex were emplaced in the order syenite/monzonite (nonfoliated, 106.6 ± 0.8 Ma; foliated, 101.7 ± 0.7 Ma; both on hornblende), followed by nepheline syenite (103.7 ± 0.8 Ma on hornblende) and then quartz monzonite (100.4 ± 3.7 Ma on biotite). 40Ar/39Ar data from Granite Mountain hornblendes yielded ages slightly older, but overlapping, those from Selawik Hills. In this suite, the silica-undersaturated phase appears to be younger (105.7 ±0.8 Ma) than the silica-saturated phase(s) (106.8 ± 0.8 Ma and 107.1 ± 0.8 Ma).
Resources
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http://dx.doi.org/10.14509/17861 |
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CSDGM IMPORT ERROR: No digtinfo/formcont |
http://www.dggs.alaska.gov/pubs/ |
Tags
- 40ar/39ar
- mesozoic
- geochronology
- albian
- granite
- cretaceous
- selawik quadrangle
- granite mountain
- early cretaceous
- ar-ar
- igneous rocks
- hornblende
- plutonic rocks
- age dates
- candle quadrangle
- analytical results