Reference Detail of

Report on Referred Fossils
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Stratigraphic range: Jurassic and Cretaceous
Kinds of fossils: Mollusks, crinoids and worms
Quadrangle or area: Coleen Quad., Eastern Alaska
Shipment No.: A-67-17
Referred by: Brosge, William P.
Report prepared by: Imlay, Ralph W.
Date: 11/09/1967

The ammonites from locality 64ADu23 are definitely Paleozoic. Loc. 64ADu53 contains a concretion but no fossils. The ammonites from locality KPO688 are defintely Lower Jurassic. The presence of Oxytoma itself indicates an age not older than latest Triassic. The crinoid columnal from locality 67ARR540.1 is definitely Mesozoic according to Porter Kier.

The pelecypods from locality 67ABe428B consist of genera that could be of Jurassic or of Cretaceous age. The species of Entolium present greatly resembles E. inequivalve Hayami (1959, Japanese Journal Geol. and Geography, V. 30, p. 154, pl. 13, figs. 3-8) from the Upper Jurassic of Japan. That species is characterized by its left valve being nearly smooth and by its right valve bearing very broad, flat concentric ribs that are separated by narrow grooves. Similar species have been described from Europe in Cretaceous beds as high as Cenomanian (e.g. Entolium orbiculare Sowerby). The Astarte present (one specimen only) resembles A. ignekensis Imlay from the Ignek and Tuktu Formations, but its ribbing does not fade ventrally as in that species. The specimen referred questionably to Panope is of little age value. The fossil evidence is not sufficient to assign the collection at locality 67ABe428B definitely either to the Jurassic or Cretaceous, but there is no question that it is younger than Triassic.

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67ARR 208A , Coleen , Pentacrinus? in dark slate and siltstone interbedded with chert; overlies silicified cherty limestone. Coleen, 67 deg. 52 1/2'N., 143 deg. 06 1/2' W.
Crinoid columnals (Paleozoic or Mesozoic)
67ARR 540.1 , Coleen , Pebbles from gravel of Howling Dog Creek. Probably from Permian(?) and post-Permian(?) outcrops upstream. Pentacrinus? Coleen, 67 deg. 11 1/2' N., 141 deg. 55' W.
Crinoid columnals (Definitely Mesozoic)
67ABe 436 , Coleen , Clams from fine massive ss in same sequence as Be428B. Coleen 67 deg. 00' N., 141 deg. 42 1/2' W.
Astarte? sp.
67ABe 428B , Coleen , Clams and scaphopod(?) from several hundred feet above base of interbedded graywacke, ferruginous sandstone and shale sequence. Coleen 67 deg. 03 1/2'N., 141 deg. 41 1/2' W.
Astarte cf. A. ignikensis Imlay
Entolium cf. E. inequivalve Hayami
Panope? sp.
Worm tubes
KPO688 (Mesozoic loc. 29340) , Coleen , British Petroleum (Alaska) Inc. Float from river bluff in the Middle Salmon Trout River about 9 miles east-southeast of Old Rampart in Porcupine River area, Coleen Quad., east central Alaska. Glenn Shale (in part). From non-calcareous, pyritic, thin-bedded mudstone interbedded with dark gray, papery shale exposed on bluff. (description from Imlay E&R report, 2/14/77) [British Petroleum (Alaska) Inc. Float from river bluff in the middle fork Salmon Fork River about 9 miles (14.4 km) east southeast of Old Rampart in Porcupine River area. Coleen quadrangle, east-central Alaska. Glenn Shale (in part). Noncalcareous, pyritic, thin-bedded mudstone interbedded with dark-gray papery shale exposed on bluff. Late Pliensbachian. (from Imlay, 1981, p. 24)]; [ USGS Mesozoic loc. 29340. Float from bluff on the Middle Salmontrout River near Old Rampart, Kandik area, east central Alaska. Amaltheus. (description from Imlay and Detterman, 1973, p. 22)]; [USGS Mes. Cat.: Lower Jurassic. Orig. No. KPO 688. From scree debris derived from river bluff in the middle Salmon Trout River which flows into Porcupine River at Old Rampart, Kandik area, east-central Alaska. Bluff consists of non-calcareous, slightly pyritic mudstone b eds from 3" to 6" thick interbedded with dark gray papery shales. Collector: British Petrol. Expl. Co., 1962]
Amaltheus sp.
Oxytoma sp.