| Sample: |
Sample No. 73AFr122B -- USGS No. 23599-PC
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| Locality: |
Field No. 73AFr122B
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| Description: |
Alaska, Yukon-Tanana Upland, Eagle D-3 Quad.; T. 1 N., R. 28 E.; 64o 55 min. 46 sec. N. Lat.; 142o 05 min. 46 sec. W. Long.; gray quartzite about 1 mile west of brachiopod locality 73AFr112, apparently same bed. Collector: H. L. Foster, 1973. (description from Dutro E&R report)[Dusel-Bacon and Harris, 2003, p. 13 provide following description: Eagle D-3 quadrangle, lat. 64o 55'46" N., long 142o 06'40" W. Collected by H.L. Foster in 1973 and identified by J.T. Dutro, Jr.] |
| Location: |
Alaska Quadrangle: Eagle D-3 Township&Range: T1N R28E
Lat.: 64o55'46 " Long.: 142o05'46 " |
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Reference
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| Title: |
Report on Referred Fossils
,
1974
(04/02)
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Both collections in this shipment contain brachiopods characteristic of Permian rocks in eastern Alaska. 73AFr112 (=72AFr445 – USGS 24951-PC) adds to the short list of forms, reported in 1972, and makes the correlation with the Tahkandit Limestone more secure. 73AFr122B, while containing only poorly preserved material, substantiates the mapped correlation of the quartzite between the two localities. Both collections are clearly Permian, probably correlated to the sandstone unit of the Tahkandit Limestone of the Nation River area. |
| Report by: |
J. Thomas Dutro
, Jr.
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| Referred by: |
Helen L. Foster
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| | Age: | Permian |
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| Title: |
New occurrences of Late Paleozoic and Triassic fossils from the Seventymile and Yukon-Tanana terranes, east-central Alaska, with comments on previously published occurrences in the same area
,
2003
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Abstract - The discovery of several new fossil occurrences of late Paleozoic conodonts and radiolarians in the Seventymile and Yukon-Tanana terranes, and of Late Triassic conodonts in the Seventymile terrane in east-central Alaska, has prompted a reevaluation of other late Paleozoic and Triassic fossils reported in the same areas. The report, in 1995, of giant parafusulinids in the Seventymile terrane within the same stratigraphic interval that more than 20 years before produced poorly preserved Permian brachiopods helped place these beds in the middle Guadalupian and to position the terrane at tropical to subtropical latitudes near ancestral North America during the Middle Permian. ..... |
| Report by: |
Cynthia Dusel-Bacon
,
Anita G. Harris
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| | Age: | Permian |
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| Comment: | Shown as fossil locality 7 on Figure 2 (listed as fossil locality 7c on p. 13) Terrane assignment, map unit, and sample lithology: Seventymile terrane. Unit Pq of Foster (1976); about 1.5 km west of localty 7a and likely the same bed. (from p. 13) Age: Permian (from p. 13) Remarks: J.T. Dutro, Jr., USGS (written commun. 1973), suggested correlation of these beds with the basal sandstone unit of the Takhandit Limestone at the type section. We believe that brachiopods are likely the same age as the fusulinids (middle Guadalupian), as the beds can be walked into the fusulinid locality and share the same lithology (see Steven, 1995) (from p. 13) Exposures of unmetamorphosed brachiopod-bearing calcareous siltstone and fine-grained quartzite were discovered in a fault slice just south of the main part of the Tintina Fault system during geologic mapping of the Eagle quadrangle (Foster, 1976)(loc. 7, fig. 2; locs. 7a-7c, table 1), in the same fault slice from which the giant fusulinids were subsequently collected. Three brachiopod collections were made in 1972 and 1973, two of which were nearby and the third 2 km to the west. The brachiopods were preserved as casts and molds. (from p. 19) We believe that because of the nearby discovery of giant parafusulinids (Stevens, 1995) in the same belt of rocks which contain the brachiopod localities, the age of the brachiopod beds in the Seventymile terrane is now updated and well constrained. The fusulinid locality is 2.5 km northwest of the westernmost brachiopod collection (locs. 6, 7, fig. 2; locs. 6, 7c, table 1) and could well be within the same stratigraphic interval. The fusulinids were discovered while field-mapping the brachiopod-bearing beds for several kilometers along strike, in blocks and boulders of brachiopod-bearing calcareous siltstone that were dug from beneath a thin layer of tundra (Stevens, 1995). Proximity, lithology, and both geologic and apparent stratigraphic position provide compelling evidence that, like the giant fusulinids, the brachiopod faunas first collected in the early 1970's are of middle Guadalupian (Wordian) age. (from p. 20) |
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