| Sample: |
Sample No. No Data
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| Locality: |
Field No. No Data
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| Description: |
A silicified megafossil bed about 1 meter thick in an unnamed limestone. Exposed along the ridgecrest west of Long Mountain, Alaska at longitude 154o 50'33"W, latitude 62o 31'59"N, center of SW1/4, NE1/4 of sec. 9, T28N, R30W, McGrath C-4 quadrangle. This locality was discovered and collected by geologists of Arco Alaska, Inc., and subsequently recollected by R.B. Blodgett. |
| Location: |
Alaska Quadrangle: Mc Grath C-4 Township&Range: T28N R30W Section: center of SW1/4, NE1/4 of sec. 9
Lat.: 62o31'59 " Long.: 154o50'33 " |
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Reference
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| Title: |
Upper Ordovician Gastropoda from west-central Alaska
,
1985
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Abstract--A brachiopod-gastropod assemblage of Late Ordovician age from the Lone Mountain area, McGrath quadrangle, west-central Alaska contains 15 species of gastropods including Pseudocryptaenia? majewskei n. sp. and Trochonemella churkini n. sp. In addition to the typical Ordovician gastropods present, such as Maclurites, three genera previously known only from the Silurian were recovered: Euomphalopterus, Pseudophorous, and Oriostoma?. The fauna is from strata that have been interpreted by some as being allochthonous in relation to cratonic North America. The paleobiogeographic affinities of the gastropods are not conclusiveby themselves, but are consistent with our view, supported by the paleobiogeographic affinities of other Paleozoic faunas of the region and lithofacies analysis and paleomagnetism, that these strata are part of a southwest-trending miogeoclinal belt that extends along the Paleozoic North America continental margin from Canada and east-central Alaska across the Tintina Fault into southwestern and Interior Alaska. |
| Report by: |
David M. Rohr
,
Robert B. Blodgett
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| | Age: | Ashgillian |
| Formation: | Unnamed (Unnamed Ordoviciain limestone unit) |
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| Comment: | Age: "Brachiopods are presented by a numerically rich, but non-diverse fauna, dominated by Tcherskidium sp. and a less abundant dolerothid. The genus Tcherskidium is known only from the Ashgillian of the Siberian Platform and adjoining regions and has been recently recognized in coeval strata of northeastern Greenland (Hurst and Sheehan, 1982). Corals identified by W.A. Oliver, Jr. (1981, written commun.) include Paleofavosites sp., Mesofavosites sp., Syringoporinus sp., Catenipora sp., Tollina sp. and Tryplasma sp. cf. T. sp. Oliver in Oliver et al. (1975). Oliver assigns this fauna a Late Ordovician age on the basis of the presence of Tollina, which "...limited to the Middle and Late Ordovician," the other corals present being "common in the Late Ordovician and Silurian." Conodonts identified by S.M. Bergstrom (1982, written commun.) include Panderodus sp. cf. P. gracilis (Branson and Mehl), Belodina sp., hindeodelliform element, probably from Ozarkodina sp., and zygognathiform element of unknown affinity. According to Bergstrom (1982, written commun.) the fauna is "...Late Ordovician in age, and probably from the upper half of the Ashgillian. However, it contains nothing which is currently really diagnostic, and this age determination is therefore necessarily tentative." (from p. 667) |
| Occurrence(s) |
| No. |
Group |
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Name |
Qty |
Notes |
| 1 |
Snails |
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Tropidodiscus sp. |
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| 2 |
Snails |
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Maclurites sp. |
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| 3 |
Snails |
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?Pachystrophia cf. P. devexa (Eichwald, 1859) |
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| 4 |
Snails |
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Paraliospira aff. P. planata Rohr, 1980 |
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| 5 |
Snails |
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Loxoplocus (Lophospira) cf. L. (L.) perangulata (Hall, 1847) |
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| 6 |
Snails |
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Trochonemella churkini n. sp. |
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| 7 |
Snails |
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Pseudocryptaenia? majewskei n. sp. |
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| 8 |
Snails |
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Euomphalopterus sp. |
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| 9 |
Snails |
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Trochonema (Trochonema) aff. T.(T.) retrorsum Ulrich and Scofield, 1897 |
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| 10 |
Snails |
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Trochonema (Eunema) sp. A |
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| 11 |
Snails |
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Trochonema (Eunema) sp. B |
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| 12 |
Snails |
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Gyronema sp. |
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| 13 |
Snails |
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Oriostoma? cf. O. angulatum (Wahlenberg, 1818) |
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| 14 |
Snails |
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Ectomaria cf. E. prisca (Billings, 1865) |
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| 15 |
Snails |
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Pseudophorus cf. P. profundus (Lindstrom, 1884) |
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| 16 |
Brachiopods |
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Tcherskidium sp. |
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dominant brachiopod at this locality |
| 17 |
Brachiopods |
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dolerothid |
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| 18 |
Tabulate Corals |
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Paleofavosites sp. |
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identified by W.A. Oliver, Jr. |
| 19 |
Tabulate Corals |
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Mesofavosites sp. |
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identified by W.A. Oliver, Jr. |
| 20 |
Tabulate Corals |
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Syringoporinus sp. |
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identified by W.A. Oliver, Jr. |
| 21 |
Tabulate Corals |
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Catenipora sp. |
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identified by W.A. Oliver, Jr. |
| 22 |
Rugose Corals |
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Tryplasma sp. cf. T. sp. Oliver in Oliver et al. (1975) |
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identified by W.A. Oliver, Jr. |
| 23 |
Conodonts |
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Panderodus cf. P. gracilis (Branson and Mehl) |
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identified by S.M. Bergstrom |
| 24 |
Conodonts |
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Drepanoistodus suberectus (Branson and Mehl) |
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identified by S.M. Bergstrom |
| 25 |
Conodonts |
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Belodina sp. |
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identified by S.M. Bergstrom |
| 26 |
Conodonts |
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hindeodelliform element, probably from Ozarkodina sp. |
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identified by S.M. Bergstrom |
| 27 |
Conodonts |
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zygognathiform element of unknown affinity |
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identified by S.M. Bergstrom |
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