ARCTIC Pliocene Marine Transgressions of Northern Alaska: Circumarctic Correlations and Paleoclimatic Interpretations’
ABSTRACT. At least three marine transgressions of Pliocene age are recorded by littoral to inner-shelf sediments of the Gubik Formation, which mantles the Arctic Coastal Plain of northern Alaska. The three recognized transgressions were eustatic high sea levels that, from oldest to youngest, are inf...
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| Format: | Text |
| Language: | English |
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1990
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.586.4454 http://pubs.aina.ucalgary.ca/arctic/Arctic45-1-74.pdf |
| Summary: | ABSTRACT. At least three marine transgressions of Pliocene age are recorded by littoral to inner-shelf sediments of the Gubik Formation, which mantles the Arctic Coastal Plain of northern Alaska. The three recognized transgressions were eustatic high sea levels that, from oldest to youngest, are informally named the Colvillian, Bigbendian, and Fishcreekian transgressions. The geochronology is based upon amino acid geochemistry, paleo-magnetic studies, vertebrate and invertebrate paleontology, and strontium isotope age estimates. Pollen, plant macrofossils, and marine vertebrate and invertebrate remains indicate that these trangressions occurred when the Arctic was at least intermittently much warmer than it is now. The Colvillian transgression took place at sometime between 2.48 and 2.7 Ma, when adjacent coastal areas supported an open boreal forest or spruce-birch wood-land with scattered pine and rare fir and hemlock. The Bigbendian transgression occurred about 2.48 Ma. Climatic conditions were probably slightly cooler than during the Colvillian transgression, but probably too warm for permafrost and too warm for even seasonal sea ice in the region. Nearby vegetation was open spruce-birch woodland or parkland, possibly with rare scattered pine. The Fishcreekian transgression took place sometime between 2.14 and 2.48 Ma and was also characterized by warm marine conditions without sea ice. During the waning stages of this transgression, however, terrestrial conditions were relatively cool, and coastal vegetation was herbaceous tundra with scattered larch trees in the vicinity. Other marine units from this time period occur around the Arctic Basin. The three oldest trangressions recognized from the Seward Peninsula may be broadly correlated with the three Pliocene transgressions of the Arctic Coastal Plain. The Tusatuvayam beds in Kamchatka possibly correlate with |
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