| Sample: |
Sample No. 62AGz84 -- USGS No. Mesozoic loc. 28661
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| Locality: |
Field No. 62AGz84
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| Description: |
Calcareous siltstone. Lat. 62o 13'29" N., Long. 148o 01'27" W., (Coords. 15.35-15.63) [Arthur Grantz, 1962, on Nowhere Creek. Lat. 62o 13'29" N., long. 148o 01'27" W., Coordinates 15.35-15.63. Talkeetna Mountains (A-3) quadrangle, Talkeetna Mountains, southern Alaska. Talkeetna Formation. Late Sinemurian. (description from Imlay, 1981, p. 26)]; Mesozoic loc. 28661 in Talkeetna Mountains A-3 quadrangle, coordinates 15.35, 15.63, lat 62°13'29" N., long 148°01'27" W. Talkeetna Mountains, Cook Inlet region. Crucilobiceras. (description from Imlay and Detterman, 1973, p. 22); [USGS Mes. Cat.: Lower Jurassic - Talkeetna Formation. Orig. No. 62AGz84. Calc. siltstone. Lat. 62°13'29" N., Long. 148°01'27" W. , (Coords. 15.35-15.63). Nowhere Ck., Talkeetna Mts. A-3 Quad., Alaska. Collector: Grantz and Gebhardt, 1962.] |
| Location: |
Alaska Quadrangle: Talkeetna Mts A-3
Lat.: 62o13'29 " Long.: 148o01'27 " |
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Reference
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| Title: |
Report on Referred Fossils
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1962
(09/19)
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Fossils from the Talkeetna Formation in collections 62AGz80 and 80A do not contain fossils of age significance. Collections 62AGz84, 84A and 84B contain the ammonite Crucilobiceras which in Europe ranges from the upper Sinemurian into the basal Pliensbachian. It is associated in collection 84 and probably in 84A with Acanthopleuroceras which is characteristic of the lower Pliensbachian. Collection 62AGz83 contains the ammonite Radstockiceras which occurs in the lower Pliensbachian of Europe. Please let me know if this data helps in dating the emplacement of the Talkeetna batholith. Also, when you find time, please send me a copy of the Talkeetna Mts. (A-3) quadrangle showing the locations of these fossil collections. |
| Report by: |
Ralph W. Imlay
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| Referred by: |
Arthur Grantz
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| | Age: | Pliensbachian (early Pliensbachian) |
| Formation: | Talkeetna Formation (Revised; Robert B. Blodgett, 12/10/2017 ) (original assignment: Talkeetna Formation) |
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| Comment: | Collections 62AGz84, 84A and 84B contain the ammonite Crucilobiceras which in Europe ranges from the upper Sinemurian into the basal Pliensbachian. It is associated in collection 84 and probably in 84A with Acanthopleuroceras which is characteristic of the lower Pliensbachian. |
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| Title: |
Report on Referred Fossils
,
1976
(12/17)
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Enclosed is a list of Lower Jurassic ammonite genera and species present in the Talkeetna Mountains. Please note that all ammonite localities of age significance are listed and that the ammonites are grouped under the stages Sinemurian, Pliensbachia and Toarcian. In Europe Paltechioceras occurs only in the highest Sinemurian. Crucilobiceras occurs mostly in the highest Sinemurian but a few species occur in the basal Pliensbachian. Their association at several localities in the Talkeetna Mountains is evidence that the beds in which they occur represent the upper Sinemurian. The ranges of most of the other ammonite genera listed under Pliensbachian and Toarcian are shown on p. C16 (fig. 6) in U.S.G.S. Prof. Paper 593-C (see discussion on p. C17-C21). Genera not listed therein include Uptonia and Apoderoceras from the basal Pliensbachian, Amaltheus from the upper Pliensbachian, Phymatoceras and Brodieia from the upper Toarcian, and Pseudolioceras from lower Toarcian to lower middle Bajocian. On the basis of these ranges the Talkeetna Formation has furnished ammonites of late Sinemurian to late Toarcian age. As explained in your letter of May 2, 1961, these fossil collections cannot reliably be assigned to stratigraphic positions within the Talkeetna Formation. If that conclusion still holds true, please try to make gross assignments to the three units as discussed in that letter. It would be of some value if the middle and upper units can be dated. Your comments will be appreciated.
Lower Jurassic Ammonites in the Talkeetna Mountains Toarcian Dactylioceras cf. D. commune (J. Sowerby) - 24787 and 29198
D. (Orthodactylites) kanense McLearn - 29198
Harpoceras cf. H. exaratum (Young & Bird) - 29198
Pseudolioceras sp. - 25317
Grammoceras? sp. - 25939
Phymatoceras? sp. - 25317, 25342
Brodieia cf. B. tenuicostata (Jaworski) - 25940
Haugia cf. H. variabilis (d'Orbigny) - 25318, 27508
H. cf. H. grandis Buckman - 24111, 24114
H. cf. H. compressa Buckman - 24114
H. sp. - 25316, 25319, 25359 Pliensbachian Leptaleoceras pseudoradians (Reynes) - 29450
Uptonia sp. juv. - 6697
Amaltheus cf. A. stokesi (J. Sowerby) - 25941
A. sp. - M2441
A. sp. - M2441
Fontanelliceras cf. F. fontanellense (Gemmellaro) - 25941, 27586, 29450
Arieticeras cf. A. domarense (Meneghini) - 24107, 27586, 29450
Protogrammoceras cf. P. platum Buckman - 24108, 25941, 29449
P. cf. P. argutum (Buckman) - 24108, 25941
P. sp. - 29450
Fanninoceras kunae McLearn - 24107, 24108, 27586
F. cf. F. carlottense McLearn - 24108, 29449
Apoderoceras cf. A. subtriangulare (Young & Bird) - 6697, M6171 Sinemurian Paltechioceras cf. P. harbledownensis (Crickmay) - 28661, 28663
Crucilobiceras cf. C. densinodulum Buckman - 28661
C. cf. C. muticum (d'Orbigny) - 28661, 28662, 28663
C. cf. C. submuticum (Oppel) - 6706, 28661
C. sp. juv. - 26772 |
| Report by: |
Ralph W. Imlay
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| Referred by: |
Arthur Grantz
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| | Age: | Sinemurian |
| Formation: | Talkeetna Formation (Revised; Robert B. Blodgett, 12/10/2017 ) (original assignment: Talkeetna Formation) |
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| Comment: | Age: Talkeetna Formation |
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| Title: |
Jurassic Paleobiogeography of Alaska
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1973
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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
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| | Age: | Sinemurian |
| Formation: | Talkeetna Formation (Revised; Robert B. Blodgett, 12/10/2017 ) (original assignment: Unknown (not given)) |
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| Comment: | Age: Sinemurian Generalized location shown as locality 5 in figure 2 |
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