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Report on Referred Fossils
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Stratigraphic range: Miocene to Pliocene?
Kinds of fossils: Mollusks
Quadrangle or area: Bering Glacier quad., Yakataga District, Alaska
Shipment No.: A-70-20M
Referred by: Plafker, George
Report prepared by: Addicott, Warren O.
Date: 06/29/1971

This report is based upon a series of collections from a 5,800 ft measured section of the lower Yakataga Formation at Kulthieth Mountain, Yakataga District, Gulf of Alaska Tertiary Province, measured and collected by George Plafker during the summer of 1970.

The collections represent far more detailed paleontologic sampling than was previously available (an earlier report on this area was written by F. S. MacNeil, A-65-1M).

Age:
the stratigraphically highest collection (M4390) may represent the Pliocene as that epoch has been recognized in previous work on Gulf of Alaska Tertiary faunas. This call is based on the Chlamys and the Neptunea that seem to be restricted to strata that have been previously assigned to the Pliocene. The age of the next to the highest collection (M4389) is indeterminate; it could also be Pliocene but the assemblage is too meager to permit an age assignment.

Localities M4386 and M4387 probably are of late Miocene age; they include the highest stratigraphic occurrence of Neptunea aff. N. tabulata (Baird) which ranges downward to the base of the Yakataga Formation and contain the pectinid Swiftopecten which heretofore has only been recorded from strata assigned to the Miocene in the Gulf of Alaska. The immediately overlying collection contains a doubtfully identified specimen of Macoma arctata which is suggestive of late Miocene age. Accordingly, a provincial boundary between the Miocene and the Pliocene can be tentatively placed in the unfossiliferous interval between 4210 and 5110 ft above the base of your measured section.

The criteria utilized by MacNeil in differentiating the provincial middle Miocene from the late Miocene are not clear. There is a recognizable faunal break between M4378-80 and M4381 based upon the highest stratigraphic occurrences of Cyclocardia n. sp., a species heretofore recorded only from strata that MacNeil assigned to the middle Miocene, and Turritella hamiltonensis. Another boundary could be drawn between the highest stratigraphic occurrence of Lituyapecten cf. L. yakatagensis (Clark) MacNeil (M4375) and the presumably antecedent species L. lituyensis (M4377). This boundary would honor MacNeil’s assignment of a provincial post-middle Miocene age to the biozone of L. lituyaensis.

This appears to be an excellent section for potential correlation of the Yakataga Formation. The collections, together with the earlier material, leave much to be desired, however, in terms of diversity. It would be very helpful to have additional material from this section. The McCoy collections from Phillips are from a 2000 ft measured section on the east side of Kulthieth Mountain (5 localities). Unfortunately, there are only one or two species in each collection and only one, M4603 (1700 ft above the base of his measured section) includes a stratigraphically diagnostic species; Chlamys cf. C. tugidakensis MacNeil (this species is indicative of a Pliocene age).

Environment:
Collections from the base of the section (M4365) up to 2520 ft above the base (M4378-80) represent a sublittoral, or neritic, environment deeper than about 10-20 fathoms. The assemblage from M4381 (3585-3670 ft above the base) indicates shoaling to low intertidal or very high sublittoral depths. M4386 (3770-4070 ft above the base), again, is probably no shallower than 10-20 fathoms based upon the occurrence of Lituyapecten. The stratigraphically higher collections may record slight shoaling based upon the occurrence of Swiftopecten, a doubtful Mytilus, and the vermetid gastropod.

The molluscan genera are suggestive of cool temperate to cold surface water temperatures, almost all of them live today in shallow water along the Gulf of Alaska coast. An exception is the genus Turritella which today ranges no farther north than the southern part of the Oregonian (temperate) molluscan province which extends northward from central California to British Columbia. In view of the other genera in the assemblage it seems likely that the Turritella was adapted to somewhat cooler water temperatures than in which it lives today along the eastern North Pacific margin.


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Brief statement of problem and remarks (from collector):
Collection are from a 6,000-feet section of the lower Yakataga Formation at Kulthieth Mountain in the Yakataga District. Part of this section was measured previously by Don J. Miller and was published in OM 187. Information is required on the age and depositional environment of this sequence and its possible correlation with other sections of Yakataga Formation in the district.

User Note module to be added
70APr 43 (Cenozoic loc. M4365) , Bering Glacier , Collections are from a 6,000-foot section of the lower Yakataga Formation at Kulthieth Mountain in the Yakataga District. Base of measured section.
Nuculana alferovi sakhalinensis Krishtofovich
Pectinid? - fragment
Undet. minute specimens - 2 taxa
70APr 44 (Cenozoic loc. M4366) , Bering Glacier , Approx. 150-320 ft above base of measured section [see 70APr 43].
Acila cf. A. taliaferroi Schenck
Clinocardium yakatagensis (Clark)?
Cyclocardia? sp. - fragment
Mya cf. M. cuneiformis (Bohm)
Nuculana cf. N. alferovi sakhalinensis Krishtofovich
70APr 47 (Cenozoic loc. M4367) , Bering Glacier , Approx. 430-700 ft. above the base of measured section [see 70APr 43].
Turritella hamiltonensis Clark
70APr 48 (Cenozoic loc. M4368) , Bering Glacier , Approx. 700-765 ft. above the base of measured section [see 70APr 43].
Clinocardium yakatagensis (Clark)
Megayoldia cf. M. thraciaformis (Storer)
Mya truncata Linnaeus
Nuculana alferovi sakhalinensis Krishtofovich?
Papyridea hamiltonensis (Clark)
70APr 49 (Cenozoic loc. M4369) , Bering Glacier , Approx. 765-855 ft above base of measured section [see 70APr 43].
Clinocardium yakatagensis (Clark)
Nuculana alferovi sakhalinensis Krishtofovich
70APr 51 (Cenozoic loc. M4370) , Bering Glacier , Approx. 910-945 ft. above base of measured section [see 70APr 43].
Mya truncata Linnaeus?
Undet. internal mold
70APr 52 (Cenozoic loc. M4371) , Bering Glacier , Approx. 945-1095 ft. above base of measured section [see 70APr 43].
Clinocardium cf. C. yakatagensis (Clark)
Cyclocardia sp.
Periploma sp.
70APr 53 (Cenozoic loc. M4372) , Bering Glacier , Approx. 1095-1110 ft. above base of measured section [see 70APr 43].
Lituyapecten cf. L. yakatagensis (Clark)
Macoma sp.
70APr 55a (Cenozoic loc. M4373) , Bering Glacier , Approx. 1180-1435 ft above base of measured section [see 70APr 43].
Lituyapecten cf. L. yakatagensis (Clark)
Macoma? sp.
70APr 55b (Cenozoic loc. M4374) , Bering Glacier , Approx. 1180-1435 ft above base of measured section [see 70APr 43].
Acila cf. A. taliaferroi Schenck
Clinocardium yakatagensis (Clark)
Macoma cf. M. calcarea Gmelin
Megayoldia cf. M. thraciaformis (Storer)
70APr 60 (Cenozoic loc. M4375) , Bering Glacier , Approx. 1845-1995 ft above base of measured section [see 70APr 43].
Lituyapecten cf. L. yakatagensis (Clark)
Mya sp.
Undet. fragment
70APr 62 (Cenozoic loc. M4376) , Bering Glacier , Approx. 2100-2270 ft above base of measured section [see 70APr 43].
Cryptonatica sp.
Neptunea aff. N. tabulata (Baird)
Papyridea?
Pododesmus?
70APr 63 (Cenozoic loc. M4377) , Bering Glacier , Approx. 2270-2395 ft above base of measured section [see 70APr 43].
Antiplanes sp.
Crepidula sp.
Fusitriton?
Naticid
Neptunea aff. N. tabulata (Baird)
Cardiid
Cyclocardia n. sp. MacNeil (1957)
Lituyapecten lituyaensis MacNeil
Mya truncata Linnaeus
Nuculana alferovi sakhalinensis Krishtofovich?
70APr 64a (Cenozoic loc. M4378) , Bering Glacier , Approx. 2395-2520 ft above base of measured section [see 70APr 43].
Calliostoma?
Lituyapecten lituyaensis MacNeil
70APr 64b (Cenozoic loc. M4379) , Bering Glacier , Approx. 2395-2520 ft above base of measured section [see 70APr 43].
Cryptonatica cf. C. russa (Gould)
Neptunea n. sp. aff. N. eurekaensis (Martin)
Neptunea aff. N. tabulata (Baird)
70APr 64c (Cenozoic loc. M4380) , Bering Glacier , Approx. 2395-2520 ft above base of measured section [see 70APr 43].
Cryptonatica cf. C. russa (Gould)
Turritella hamiltonensis Clark?
Neptunea aff. N. tabulata (Baird)
Cyclocardia n. sp. MacNeil (1957)
Macoma?
70APr 68 (Cenozoic loc. M4381) , Bering Glacier , Approx. 3585-3670 ft above base of measured section [see 70APr 43].
Securella?
Barnacle plate
Undet. genus with a relatively large, flat test
70APr 72a (Cenozoic loc. M4386) , Bering Glacier , Approx. 3770-4070 ft above base of measured section [see 70APr 43].
Neptunea aff. N. tabulata (Baird)
Cardiid
Lituyapecten lituyaensis MacNeil
Mya truncata Linnaeus
Spisula cf. S. albaria (Conrad, 1848)
Spisula cf. S. albaria goodspeedi Etherington
70APr 72b (Cenozoic loc. M4387) , Bering Glacier , Approx. 3770-4070 ft above base of measured section [see 70APr 43].
Trichotropis aff. T. cancellatus Hinds
Undet. fragment
Vermetid
Cyclocardia sp.
Swiftopecten cf. S. donmilleri MacNeil
Swiftopecten cf. S. wattsi (Arnold)
70APr 73 (Cenozoic loc. M4388) , Bering Glacier , Approx. 4070-4210 ft above base of measured section [see 70APr 43].
Neptunea or
Volutopsius
Trichotropis sp.
Cardiid
Clinocardium cf. C. ciliatum (Fabricius)
Cyclocardia sp.
Macoma? cf M. arctata (Conrad)
Macoma cf. M. incongrua (von Martens)
Mya?
70APr 78 (Cenozoic loc. M4389) , Bering Glacier , Approx. 5110-5235 ft above base of measured section [see 70APr 43].
Neptunea?
Cyclocardia sp.
Panomya sp.
Undet. fragment
70APr 79 (Cenozoic loc. M4390) , Bering Glacier , Approx. 5235-5800 ft above base of measured section [see 70APr 43].
Neptunea aff. N. lyrata (Gmelin)
Vermetid
Astarte?
Chlamys aff. C. tugidakensis MacNeil
Cyclocardia
Mytilus?
Undet. fragment