| Sample: |
Sample No. 67AMk-233 -- USGS No. Mesozoic loc. 29891
|
| Locality: |
Field No. 67AMk-233
|
| Description: |
E.M. MacKevett, Jr., 1967, NE1/4NW1/4 sec. 26, T. 4 S., R. 16 E., McCarthy (B-4) quadrangle, Wrangell Mountains. Upper member of McCarthy Formation, a few hundred feet (100 m) above base of member. Hettangian. (from Imlay, 1981, p. 25) [No description given in original E&R report of Imlay, 2/20/68]; [USGS Mesozoic Iocs. 29890 and 29891. About 15 miles northeast of McCarthy, northern part of sec. 26, T. 4 S., R. 16 E., near NW. cor. McCarthy B-4 quadrangle, southern Wrangell Mountains, eastern Alaska. Waehneroceras and Psiloceras. (description from Imlay and Detterman, 1973, p. 21)]; [Imlay, R.W., and Detterman, R.L., 1973, Jurassic Paleobiogeography of Alaska: U.S. Geological Survey Professional Paper 801, 34 p. [USGS Mes. Cat.: Lower Jurassic - McCarthy Formation. Orig. No. 67AMk 233. Upper Member, NW 1/4 sec. T. 4 S., R. 16 E., McCarthy (B-4) Quad., Alaska. Collector: McKevett, 1967] |
| Location: |
Alaska Quadrangle: Mc Carthy B-4 Township&Range: T4S R16E Section: NE1/4NW1/4 sec. 26 |
|
|
|
Reference
|
|
|
|
| Title: |
Report on Referred Fossils
,
1968
(02/20)
|
|
|
| Report by: |
Ralph W. Imlay
|
| Referred by: |
E. M. MacKevett
, Jr.
|
|
|
|
| | Age: | Hettangian (probably Hettangian) |
|
|
|
|
|
|
| Comment: | The fossils submitted probably represent the Hettangian stage at the base of the Jurassic. Collection 67AMk233 contain ammonites that almost certainly belong to the genus Psiloceras. The ammonite in collection 67AWk113 probably include both Psiloceras and Waehneroceras. The specimens differ considerably from any of the Sinemurian ammonite genera previously found in the upper member of the McCarthy Formation. I assume you have shown these ammonites already to Norm Silberling and that he has excluded them from the Triassic. If not, perhaps we should send them to him for examination. |
| Occurrence(s) |
| No. |
Group |
|
Name |
Qty |
Notes |
| 1 |
Ammonoids |
|
Psiloceras |
|
|
|
|
| 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: | Hettangian |
| Formation: | McCarthy Formation (McCarthy Formation (Upper Member)) |
|
|
|
|
|
| Comment: | Age: Hettangian Generalized location shown as locality 8 in figure 2 |
|
|
|
|