Sample Detail of
Sample: Sample No. 57ADt13 -- USGS No. Mesozoic loc. 26590
Locality: Field No. 57ADt13
Description: Chinitna Formation. Labeled basal 100 feet of Naknek fm. South Shore Chinitna Bay. (description from Imlay E&R report of 1/22/58; Shipment A-58-1)[Transmittal sheet of Detterman, dated 12/18/57 provides following description: "Naknek formation; basal 100 feet; dark greenish to gray siltstone with interbeds of yellowish green sandstone, limestone lenses and concretions; Coords: 17.2-17.48; 59o 49'55"N, 153o 01'25"W. South shore Chinitna Bay."][Shown as locality 274 on Pl. 3 of Detterman and Hartsock, 1966 - Note by R.B. Blodgett: digitization of this point gives approx. lat. 59o 50'03" N., 153o 01'02" W. - this differs drastically from that given above in transmittal sheet of Detterman.]
Location: Alaska Quadrangle: Iliamna D-1
Lat.: 59o49'55 " Long.: 153o01'25 "
Reference
Title: Report on Referred Fossils ,  1958 (01/22)
Your collections from the Gaikema member of the Tuxedni formation are rather meagre for an age determination. They contain, however, the same varied pelecypod faunule as has been found in other seasons. The collections made by Hartsock, Kellum, Kirschner, Miller and others suggest that the Gaikema member is equivalent to the lower part of the European zone of Otoites sauzei and that the underling siltstone member is equivalent to the zone of Sonnina sowerbyi.

The collections from the Fitz Creek member are excellent. They contain an assemblage that is correlated with the Otoites sauzei zone (See Arkell, 1956, Jurassic Geology of the World, p. 542).

The only other item of interest is your assignment of collection 57ADt13 to the basal part of the Naknek formation. The ammonites present, however, belong to a compressed subgenus of Cadoceras that is common in the upper part of the Chinitna formation on Chinitna Bay and Tuxedni Bay. This part of the Chinitna formation probably disappears southward toward Iniskin Bay. At least the ammonites from the top of the Chinitna formation near Iniskin Bay are identical with those found in the middle part of the formation on Chinitna Bay. You may want to check this relationship next summer.
Report by: Ralph W. Imlay
Referred by: Robert L. Detterman
Age: Jurassic
Formation: Chinitna Formation
Comment:The only other item of interest is your assignment of collection 57ADt13 to the basal part of the Naknek formation. The ammonites present, however, belong to a compressed subgenus of Cadoceras that is common in the upper part of the Chinitna formation on Chinitna Bay and Tuxedni Bay. This part of the Chinitna formation probably disappears southward toward Iniskin Bay. At least the ammonites from the top of the Chinitna formation near Iniskin Bay are identical with those found in the middle part of the formation on Chinitna Bay. You may want to check this relationship next summer.
Occurrence(s)
No. Group Name Qty Notes
1 Ammonoids Cadoceras (Stenocadoceras) multicostatum Imlay
2 Bivalves Grammatodon sp.

Title: Geology of the Iniskin-Tuxedni Region, Alaska [last half of single issue publication] ,  1966
Report by: Robert L. Detterman , John K. Hartsock
Age: Callovian
Formation: Chinitna Formation - Paveloff Siltstone Member (Paveloff Siltstone Member)
Comment:Geographic location: Chinitna Bay area
Map reference (pl. 3): 274
Stratigraphic position below top of formation (ft): 0-100
all above data from Table 11, p. 48
Occurrence(s)
No. Group Name Qty Notes
1 Bivalves Grammatodon sp.
2 Ammonoids Cadoceras (Stenocadoceras) multicostatum Imlay