| Title | Miocene and Pliocene lacustrine and fluvial sequences, Upper Ramparts and Canyon Village, Porcupine River, east-central Alaska |
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| Author | Fouch, T D; Carter, L D; Kunk, M J; Scott Smith, C A; White, J M |
| Source | Quaternary International vol. 22/23, 1994 p. 11-29, https://doi.org/10.1016/1040-6182(94)90004-3 |
| Year | 1994 |
| Alt Series | Geological Survey of Canada, Contribution Series 49094 |
| Publisher | Elsevier BV |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Alaska; Upper Ramparts River; Porcupine River; Canyon Village; United States of America |
| Lat/Long WENS | -142.5000 -141.0000 67.5000 67.0000 |
| Subjects | surficial geology/geomorphology; sedimentology; Miocene; Pliocene; unconformities; structural features; depositional environment; fluvial deposits; lacustrine deposits; lithology; palynology; fossils;
hydrologic environment; stratigraphic correlations; pollen; Tertiary |
| Illustrations | sketch maps; cross-sections; stratigraphic columns |
| Abstract | Cenozoic strata exposed along the Porcupine River between the Upper Ramparts and Canyon Village, Alaska, can be divided into five unconformity-bounded units (sequences) which are: lower and middle
Miocene unit A, the white sandy fluvial sequence with peat beds; middle Miocene unit B, the basalt sequence-part B1 is basalt, and part B2 is organic-rich sedimentary beds; upper Miocene unit C, mudrock-dominated lake sequence; late Miocene or
Pliocene to Pleistocene unit D, terrace gravels, detrital organic matter and associated sediments, and Holocene unit E, mixed sand and gravel-rich sediment and other sedimentary material including peat and eolian silt. The sequence (unit A) of lower
and middle Miocene fluvial deposits formed in streams and on flood plains, just before the inception of local volanism. Fossil pollen from unit A suggests conifer-dominated regional forests and cool temperate climates. Peat beds and lake deposits
from unit B contain pollen that indicates a warmer temperate climate coinciding with the middle Miocene thermal maximum. The lake deposits (unit C) downstream from the basalts accumulated in a small basin which resulted from a hydrologic system that
was dammed in the late Miocene but breached soon thereafter. The lower part of the terrace gravels (unit D) expresses breaching of the dammed hydrologic system (of unit C). The Porcupine River became a major tributary of the Yukon River in late
Pleistocene time when Laurentide ice blocked drainage from the Yukon interior basins causing meltwater to spill over the low divide separating it from the Porcupine River drainage initiating erosion and capture of the Yukon interior basins.
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| GEOSCAN ID | 194517 |
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