of
Sample: Sample No. 57ADt2 -- USGS No. Mesozoic loc. 26597
Locality: Field No. 57ADt2
Description: "Fitz Creek" member of Tuxedni Formation. Middle Part. Tonnie Creek. (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: "Fitz Creek member; middle part; greenish-gray nodular weathering siltstone with interbeds of sandstone; Tonnie Creek; Coords 9.4-12.5. 59o 45'25"N, 153o 14'30"W; Section 8, T.5S-R23W."][Shown as locality 77 on Pl. 3 of Detterman and Hartsock, 1966]
Location: Alaska Quadrangle: Iliamna D-1
Township&Range: 5S 23W Section: 8
Lat.: 59o45'25 " Long.: 153o14'30 "
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 (Jurassic, Otoites sauzei Zone)
Formation: Fitz Creek Siltstone ("Fitz Creek" member of Tuxedni Formation)
Comment: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).
Occurrence(s)
No. Group Name Qty Notes
1 Ammonoids Chondroceras defontii (McLearn)
2 Ammonoids Calliphylloceras sp.
3 Bivalves Inoceramus sp.
4 Bivalves Oxytoma sp.
5 Belemnites Belemnites undetermined

Title: Geology of the Iniskin-Tuxedni Region, Alaska ,  1966
Report by: Robert L. Detterman , John K. Hartsock
Age: Bajocian
Formation: Fitz Creek Siltstone
Comment:Geographic location: Tonnie Creek-Twist Creek area
Map reference (pl. 3): 77
Stratigraphic position below top of formation (ft): 400-450
all above data from Table 6, p. 32
Occurrence(s)
No. Group Name Qty Notes
1 Bivalves Inoceramus sp.
2 Bivalves Oxytoma sp.
3 Ammonoids Macrophylloceras sp. indet.
4 Ammonoids Chondroceras defontii (McLearn)
5 Belemnites Belemnites