Unit symbol: | Twv |
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Age range | Tertiary, Pliocene to Oligocene (33.9 to 1.806 Ma) |
Lithology: | Igneous - Volcanic |
Group name: | Volcanic rocks, undivided |
Source map | Richter, D.H., Preller, C.C., Labay, K.A., and Shew, N.B., 2006, Geology of Wrangell-Saint Elias National Park and Preserve, southcentral Alaska: U.S. Geological Survey Scientific Investigations Series Map SIM-2877, 15 p., 1 sheet, scale 1:350,000. |
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Symbol | Th |
Unit name | Hypabyssal rocks |
Description | Dacite, andesite, and rhyodacite porphyry. Typically strongly porphyritic. Correlates with younger porphyry of Nabesna quadrangle and with hypabyssal rocks associated with the Wrangell Lava in Alaska and Canada. Subdivision of unit Th of MacKevett (1978) south of range divide and Chitna River valley |
Lithology | Igneous |
Label | Twd |
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Description | Wrangell Lava, dome and hypabyssal rocks |
Geologic age | Pliocene |
Geologic setting | Extrusive |
Lithology | Form | Importance |
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Hypabyssal-dacite < Felsic-hypabyssal < Hypabyssal < Igneous | Dome | Indeterminate, major |
Hypabyssal-dacite < Felsic-hypabyssal < Hypabyssal < Igneous | Dome | Indeterminate, major |
Hypabyssal-rhyolite < Felsic-hypabyssal < Hypabyssal < Igneous | Dome | Indeterminate, major |
Andesite < Mafic-volcanic < Volcanic < Igneous | Dome | Minor |