Reference Detail of

Report on Referred Fossils
Edit Reference Add/Edit Sample Sample List Show Map

Stratigraphic range: Upper Devonian
Kinds of fossils: Brachiopods
Quadrangle or area: Survey Pass Quad., Alaska
Shipment No.: A-77-20
Referred by: Grybeck, Donald
Report prepared by: Dutro, J. Thomas, Jr.
Date: 10/07/1977

Summary: This report covers 7 collections, received separately and combined as one shipment. The two collections of Nelsons compare well with others reported from shipments A-77-13 and A-77-17. In terms of the facies analysis of the report on A-77-17, 77ANS 126A falls into category 5 (fully marine) and 77ANS 130B is in category 1 (non-marine). Of the 4 collections made by Margo Toth, 3 are possibly early Late Devonian (Frasnian) and may well represent the "Beaucoup Formation" which lies below the restricted Hunt Fork Shale in the Philip Smith Mtns., Chandler Lake and northern Wiseman quadrangles. These are collections 77AMT 122B, 125A and 139B; all contain possible Atrypa, a genus not known from the younger Late Devonian (Famennian). One collection, 77AMT 158A, does not contain any recognizable organic remains. The final collection, 77ADB 115F, does not contain diagnostic megafossils. However, it too may be Frasnian and represent some part of the "Beaucoup Formation". This, and the 3 probable Frasnian collections, will be processed for microfossils.
By way of elaboration on the stratigraphic significance of 2 collections from A-77-17 which yielded conodonts (see report of Harris and Yochelson dated 10/5/77), I suggest that both 77ANS 202A and 77ANS 205A also represent the "Beaucoup Formation" of Frasnian age. Purple and green phyllite and orange-weathering limestones are two characteristic rock types found in that formation.
The "Beaucoup Formation" is a unifying stratigraphic concept in the early Late Devonian of the central Brooks Range and its type section and regional significance are the subjects of a paper now in preparation by Brosge, Reiser and me.

User Note module to be added
77ANS126A , Survey Pass , 1 km S. 78 E. from Survey Pass; rubble at base of 2 m. high outcrop of reddish brown weathering, fine grained, calcareous limonitic quartz sandstone. Collector: S. Nelson, 1977.
indeterminate echinoderm debris
Cyrtospirifer? sp.
rhynchonelloid fragments
77ANS130B , Survey Pass , 2.5 km N. 20 deg. W. from Survey Pass; dark gray and purple phyllitic shale inter-bedded with light gray, fine grained calcareous limonitic quartz-feldspar sandstone. Collector: S. Nelson, 1977.
Indeterminate plant scraps
77AMT122B , Survey Pass , 2 km from summit of Plateau Mtn. at bearing of N. 42 deg. E.; from top 2 ft of 7 m. thick vertical section of limestone. Collector: M.Toth, 1977.
Indeterminate echinoderm debris
Atrypa? sp.
Schizophoria? sp.
Small spiriferoid with a well-defined fold and sulcus
77AMT125A , Survey Pass , approx. same loc. as 122B, but 2 1/2 km from summit of Plateau Mtn. at bearing of N. 38 deg. E.; from middle of 20 m. thick limestone. Collector: M.Toth, 1977.
Atrypa? sp.
A large spiriferoid
77AMT139B , Survey Pass , float from saddle, approx. 10.5 km. from summit of Pateau Mtn. at bearing S. 87 deg. E. Collector: M.Toth, 1977.
Indeterminate echinoderm debris
Atrypa? sp.
77ADB115F , Survey Pass , elev 4200 ft. Collector: D. Brew, 1977.
Indeterminate echinoderm debris
Deformed brachiopod fragments