Revisiting the Ruby Terrane: Insights from Geologic Mapping in the Moran Area, Central-Interior Alaska
logic mapping in the Moran Dome area of Central-Interior Alaska. The Moran project map area is located 150 miles west of Fairbanks, in the eastern Kokrines Hills, immediately north of the Yukon River, which follows the Kaltag, re-gional-scale, right-lateral, strike-slip fault system. DGGS geologists...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.665.262 http://alaskageology.org/documents/14/October+2014+Newsletter.pdf |
| Summary: | logic mapping in the Moran Dome area of Central-Interior Alaska. The Moran project map area is located 150 miles west of Fairbanks, in the eastern Kokrines Hills, immediately north of the Yukon River, which follows the Kaltag, re-gional-scale, right-lateral, strike-slip fault system. DGGS geologists have distinguished eight mappable units, two re-gional metamorphic events, at least four ductile deformation events, and a single intrusive event followed by brittle de-formation; at least three metallogenetic events overlap the area. The Proterozoic to Paleozoic Ruby Terrane (RT) underlies most of the Moran area. DGGS subdivides the RT into five meta-sedimentary units, which spatially correspond with interpretations of the DGGS Moran airborne geophysical da-ta. From structurally lowest to highest they are paragneiss and pelitic schist, calcareous-mica-albite-quartz schist, massive to foliated graphitic quartzite, pelitic schist and metagrit, and an interlayered graphitic quartz schist and quartzite unit. Detrital zircon U/Pb ages in three samples of the RT are predominantly Paleozoic with a minimum inter-preted age of middle Triassic. In contrast, a fourth sample from the pelitic schist-metagrit unit is characterized by abun-dant Paleoproterozoic detrital zircons, similar to samples from the Wickersham grit and the Yukon-Tanana terrane. Shallow-dipping S2 foliation is axial planar to recumbent F2 isoclinal folds, and refolded by upright, open-to-close-profile NE- and SW-plunging F3 folds and lesser upright, open-to-close-profile NW- and SE-plunging F4 folds. Stretch-ing lineations plunge shallowly to the NW and SE. A Kaltag-parallel, steep, E–W-trending, S3 foliation cuts S2 along the |
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