| Sample: |
Sample No. 64ADt781A -- USGS No. Mesozoic loc. 29115
|
| Locality: |
Field No. 64ADt781A
|
| Description: |
Pebble-cobble congl. with dark greenish-gray sandstone interbeds app. 300 feet stratigraphically above previous lot [64ADt780]: 2.1 miles N. 30o E. of mouth of Amakdedori Creek; coords. 1.25-4.95 (from E&R report); [USGS Mesozoic loc. 29115. Iliamna Lake region, 2.1 miles N. 30° E. of mouth of Amakdedori Creek, lat 59°18'25" N., long 154°05'40" W., coordinates 1.25, 4.95, Iliamna B-3 quadrangle, Cook, Inlet region. Inoceramus ambiguus Eichwald. (description from Imlay and Detterman, 1973, p. 24)]; [USGS Mes. Cat.: 29115 (64ADt781A) Jurassic, Tuxedni Group. Pebble-Cobble congl. with dark greenish-gray ss. interbeds app. 300' strat. above loc. 64ADt+I322780A. 2.1 miles N. 30° E. of mouth of Amakdedori Creek, Lat. 59°18'25" N., Long. 154°05'40" W. Coords. 1.25-4.95. Coll. by R.L. Detterman, 1964. Iliamna Lake Region, Iliamna B-3 quad., S.W. Alaska] |
| Location: |
Alaska Quadrangle: Iliamna B-3
Lat.: 59o18'25 " Long.: 154o05'40 " |
|
|
|
Reference
|
| Title: |
Report on Referred Fossils
,
1964
(12/02)
|
|
|
| Report by: |
Ralph W. Imlay
|
| Referred by: |
Robert L. Detterman
|
|
|
|
| | Age: | Middle Jurassic-Early Cretaceous |
| Formation: | Tuxedni Group |
|
|
|
|
|
| Comment: | The species of Myophorella is the same as at loc. 64ADt780A. Inoceramus ambiguus Eichwald on the Iniskin Peninsula ranges from the Fitz Creek Siltstone through the Chinitna Formation. The range of the ammonite Holcophylloceras is Middle Jurassic (Bajocian) to Lower Cretaceous (Aptain). The range of the trigoniid is from the middle Lower Jurassic to the Neocomian. It attained its greatest development in the Upper Jurassic. In the Cook Inlet region and the Alaska Peninsula the genus ranges from the base of the Tuxedni Group into the Chinitna Formation. These ranges do not permit a close age or stratigraphic assignment. The presence of Inoceramus ambiguus shows, however, that the beds containing the fossils are younger than the Red Glacier Formation and older than the Naknek Formation. |
|
|
| Title: |
Jurassic Paleobiogeography of Alaska
,
1973
|
|
ABSTRACT: Jurassic marginal seas occupied considerable areas in southern and northern Alaska and in the western part of the Kuskokwim region of southwestern Alaska. They appear to have been absent during late Callovian time, much restricted during Hettangian, Bathonian, early Oxfordian and late Tithonian time, and most extensive during Sinemurian, Bajocian, and late Oxfordian to middle Tithonian time. A large area in central Alaska was probably never covered. A southwestern prolongation of that area from the Talkeetna Mountains westward to the western end of the Alaska Penin- sula was the site of granitic intrusions during late Early Jurassic time and of extensive erosion during Middle and Late Jurassic time. Variations in the rate of uplift of the area of these granitic intrusive rocks may explain why marine transgressions and regressions were at different times in southern than in northern Alaska during the Bajocian and Bathonian. Connection of the northern and southern marginal seas occurred through Yukon Territory and eastern- most Alaska. The Jurassic ammonite succession in Alaska is similar to that in central and northern Europe and northern Asia. In Lower Jurassic beds, it is essentially identical. In Bajocian and in Oxfordian to lower Kimmeridgian beds, the ammonite succession in Alaska differs from that in the other areas mainly by the presence of some genera found only in areas bordering the Pacific Ocean and by the absence of a few genera common in central and northern Europe. In con- trast, the Bathonian rocks of Alaska contain ammonites, such as Arcticoceras, Arctocephalites, and Cranocephalites, that are widespread in the Arctic region but are unknown in central Europe. Comparisons with the Tithonian of Europe are not possible because ammonites of that age, other than Lytoceras and Phylloceras, are not yet known from Alaska. The Alaskan Jurassic ammonites of late Pliensbachian Age and of Bathonian to early Kimmeridgian Age belong mostly to the Boreal realm and have very little in common with Tethyan realm ammonites such as those found in areas bordering the Mediterranean Sea. |
| Report by: |
Ralph W. Imlay
,
Robert L. Detterman
|
|
|
|
| | Age: | Bajocian |
|
|
|
|
|
|
| Comment: | Age: Bajocian Generalized location shown as locality 24 in figure 4 |
|
|
|
|