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Reference
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| Title: |
The Late Triassic Bivalve Monotis in Accreted Terranes of Alaska
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1997
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ABSTRACT--Late Triassic bivalves of the genus Monotis occur in at least 16 of the lithotectonic terranes and subterranes that together comprise narly all of Alaska, and they also occur in the Upper Yukon region of Alaska where Triassic strata are regarded as representing non-accretionary North America. On the basis of collections made thus far, 14 kinds of Monotis that differ at the species or subspecies level can be recognized from Alaska. These are grouped into the subgenera Monotis (Monotis), M. (Pacimonotis), M. (Entomonotis), and M. Eomonotis. In places, Monotis shells of one kind or another occur in rock-forming abundance. On the basis of superpositional data from Alaska, as well as from elsewhere in North America and Far Eastern Russia, at least four distinct biostratigraphical levels can be discriminated utilizing Monotis species. Different species of M. (Eomonotis) characterizes two middle Norian leves, both probably within the upper middle Norian Columbianus Ammonite Zone. |
| Report by: |
Norman J. Silberling
,
J. A. Grant-Mackie
,
K. M. Nichols
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| | Age: | Norian (early late Norian) |
| Formation: | McCarthy Formation |
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| Comment: | Plate 4 explanation: Monotis (Pacimonotis) subcircularis. USGS Mesozoic loc. M1690 (10 m stratigraphically lower than M1691). Wrangellia terrane. 1-3. Left valves. 4-5. Right valves. |
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