Reference Detail of

Report on Referred Fossils
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Stratigraphic range: Triassic? & Jurassic
Kinds of fossils: Mollusks, crinoids & brachiopods
Quadrangle or area: Demarcation Pt., Mt. Michelson, Table Mountain, NE Alaska
Shipment No.: A-71-9
Referred by: Detterman, Robert L.
Report prepared by: Imlay, Ralph W.
Date: 08/24/1971

The fossil collections described in letters dated July 6 and 19, 1971 are probably in part of Triassic age as indicated by the presence of monotid pelecypods at locality 71ADt283. The Pliensbachian is represented definitely by Amaltheus at locality 71ADt300C. The late Bathonian, as defined by John Callomon, is represented by Arcticoceras at locality 71ADt330D (or 300D). The Cadoceras from that locality has a black instead of a reddish-brown matrix and appears to have been rounded by rolling. It reminds me of Cadoceras comma Imlay from southern Alaska. It probably comes from higher beds than Arcticoceras, judging by the ranges of those genera in northern Canada and east Greenland. The late Jurassic (middle Kimmeridgian to early Tithonian) is represented by Buchia rugosa (Fischer) at locality 71ADt322.

The Buchias from localities 71ADt325 and 325A are probably not specifically determinable but will be sent to Dave Jones. The monotid from locality 71ADt283, will be sent to Norm Silberling.

Please check Mes. Loc. 30075 in order to determine proper field number. Also, check all stratigraphic and geographic descriptions and revise as needed.

I would like to have your opinion considering the relative stratigraphic positions of Arctocephalites and Reineckeia in the sequence near the Canning River as measured by the BP geologists. Is the position of Arctocephalites above Reineckeia normal or is it due to faulting or folding?

User Note module to be added
71ADt300A (Mesozoic loc. 30072) , Demarcation Point , Cut bank on west side of Aichilik River, about 2.5 miles N. 30 deg. E. of VABM ATTE, north front of Brooks Range, about Lat. 69 deg. 33' N., Long. 143 deg. 05' W. About 500-700 ft. above base of Kingak Formation.
Brachiopods undetermined
71ADt300B (Mesozoic loc. 30073) , Demarcation Point , Same place as Mes. loc. 30072 but ? feet higher in sequence.
Pentacrinus sp.
Worm tubes?
Pelecypods, external molds
71ADt300C (Mesozoic loc. 30074) , Demarcation Point , Same place as Mes. loc. 30072 but about 300 feet higher in sequence.
Amaltheus cf. A. stokesi (J. Sowerby)
Ostrea? sp.
71ADt330D (71ADt330D as labeled on bag) (Mesozoic loc. 30075) , Demarcation Point , Probably same as 71ADt300D described in letter of July 19, 1971 and, if so, are from beds about 200 feet higher stratigraphically than Mes. loc. 30074. (description from E&R report); USGS Mesozoic loc. 30075. Aichilik River, lat 69°33' N., long 143°05' N., northeastern Alaska. Arcticoceras ishmae (Keyserling) and Choffatia? sp. (description from Imlay and Detterman, 1973, p. 24); [USGS Mes. Cat.: 30075 (71ADt330D). Jurassic-Kingak Sh. About 200 ft. higher than 30074 at same place]
Arcticoceras kochi Spath
Arcticoceras kochi var. pseudolamberti Spath
Choffatia cf. C. subbakeriae (d'Orbigny)
Cadoceras sp. (probably float)
71ADt322 (Mesozoic loc. 30076) , Table Mtn , Joe Creek, 11.5 miles N. 75 deg. W. of point where Joe Creek crosses border into Canada. Concretions in black fissile clay shale. Probably same locality collected by Mangus in 1969. (Mes. loc. 29872); USGS Mesozoic Iocs. 29872, 29897, and 30076. Ridge south of Joe Creek, 11.5 miles N. 75° W. of point where creek crosses International Boundary, Table Mtn. quadrangle, lat 68°58' N., long 146°38' W., northeast Alaska. Buchia rugosa (Fischer). (description from Imlay and Detterman, 1973, p. 26); [USGS Mes. Cat.: 30076 (71ADt322). Jurassic - Kingak Sh. Joe Creek, 11.5 miles N75°W of point where Joe Creek crosses International border into Canada. Probably same locality as Mangus 1969 collection. Black fissile sh.]
Buchia rugosa (Fischer)
71ADt283-unit 10 (Mesozoic loc. 30077) , Demarcation Point , West of Aichilik River, 0.6 mile N. 58 deg. W. of VABM Atte. Black fissile shale 525-550 feet above base of Kingak Formation.
Monotid pelecypod (probably Triassic)
Clay ball
71ADt325 (Mesozoic loc. 30078) , Table Mtn , Joe Creek, 10.6 miles west of Canadian border. Green-gray siltstone from 200-300 feet higher than Mes. loc. 30076 (71ADt322) (from E&R report); USGS Mesozoic Iocs. 30078 and 30079. On Joe Creek, 10.6-11 miles west of Canadian border and 300 feet or less higher stratigraphically than Mesozoic loc. 30076, which has furnished Buchia rugosa (Fischer). Table Mountains quadrangle, northeast Alaska. Buchia unschensis (Pavlow). (description from Imlay and Detterman, 1973, p. 27)
Buchia sp.
71ADt325A (Mesozoic loc. 30079) , Table Mtn , On Joe Creek, 11 miles from border and between Mes. locs. 30076 and 30078 (71ADt322 and 325). Gray siltstone. (from E&R report); USGS Mesozoic Iocs. 30078 and 30079. On Joe Creek, 10.6-11 miles west of Canadian border and 300 feet or less higher stratigraphically than Mesozoic loc. 30076, which has furnished Buchia rugosa (Fischer). Table Mountains quadrangle, northeast Alaska. Buchia unschensis (Pavlow). (description from Imlay and Detterman, 1973, p. 27);[USGS Mes. Cat.: 30078 (71ADt325). Joe Creek, 10.6 miles west of border with Canada. Green-gray siltstone 200-300 ft higher than 30076 (71ADt322). Coll. by Detterman, 1971.]
Buchia sp.
70ARr388 (Mesozoic loc. 30080) , Mt Michelson , Black Island on Canning River, 3.4 miles south of mouth of Nanook Creek. From black clay shale near top of Kingak Formation.
Pentacrinus subangularis var. alaska Springer
Plicatula sp.
70ARr430 (+45 unit 3) , Mt Michelson , West Fork of Marsh Creek, 14.2 miles N. 85 deg. W. of Sadlerochit Springs. Siltstone.
Belemnite fragments