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Reference
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| Title: |
Report on Referred Fossils
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1980
(03/10)
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| Report by: |
Norman J. Silberling
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| Referred by: |
D. P. Cox
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| | Age: | Carnian-Norian (late Carnian - early Norian) |
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| Comment: | This report concerns the fragmentary impressions of halobiid bivalve shells ...... The best of these impressions clearly shows the zone or band of anterior bending of the ribbing characteristic of some species of Halobia and the general aspect of the ribbing is like that of the kind commonly referred to H. superba whose age range is late Karnian-early Norian, or about the middle of the Late Triassic.
The stratigraphic and tectonic setting of such a limestone could be any of the following: (1) A fault sliver of a Chitistone Limestone or Nizina Limestone equivalent and hence part of the Wrangellia terrane south of the Talkeetna thrust. In fact, similar Halobias, along with upper Karnian ammonites, occur in a fault sliver of similar limestone between the Nikolai Green and Wrangellia uper Paleozoic rocks about four miles farther east. (2.) A lens within the youngest part of the Nikolai Greenstone, the character of which is not known in this area. (3) A non-Wrangellian unit from the foot-wall of the Talkeetna thrust. However, the rocks that crop out, beneath the Talkeetna thrust in the immediate area are either questionable Jura-Cretaceous flysch or else belong to the so-called Clearwater terrane whose limestones, as presently known, are of different kind and much younger in age within the Triassic. |
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