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Authors: Silberling, Norman J. , Grant-Mackie, J. A. , Nichols, K. M.
Editors:
Date: /1997
Title: The Late Triassic Bivalve Monotis in Accreted Terranes of Alaska
2151 , , 21 p. , 11 pls.
Host: U.S. Geological Survey Bulletin :
Document Type: Article\Abst.\Chapter\report
Annotation: ABSTRACT--Late Triassic bivalves of the genus Monotis occur in at least 16 of the lithotectonic terranes and subterranes that together comprise narly all of Alaska, and they also occur in the Upper Yukon region of Alaska where Triassic strata are regarded as representing non-accretionary North America. On the basis of collections made thus far, 14 kinds of Monotis that differ at the species or subspecies level can be recognized from Alaska. These are grouped into the subgenera Monotis (Monotis), M. (Pacimonotis), M. (Entomonotis), and M. Eomonotis. In places, Monotis shells of one kind or another occur in rock-forming abundance.

On the basis of superpositional data from Alaska, as well as from elsewhere in North America and Far Eastern Russia, at least four distinct biostratigraphical levels can be discriminated utilizing Monotis species. Different species of M. (Eomonotis) characterizes two middle Norian leves, both probably within the upper middle Norian Columbianus Ammonite Zone.
UserNote
G662 of U.S. Grant and party, 1909 (Mesozoic loc. 6380) , Seldovia , Kenai Peninsula, southern Alaska: north side of Port Graham; lat 59 deg. 21'08" N., long 151 deg. 48' W. Coll.: U.S. Grant and party, 1909, field No. G662. [Seldovia 1:250,000 quadrangle; Peninsular terrane] (description from Silberling et al., 1997, p. 18)
Halobia lineata
G673 of U.S. Grant and party, 1909 (Mesozoic loc. 6382) , Seldovia , Kenai Peninsula, southern Alaska: south side of Port Graham; lat 59 deg. 21'02" N., long 151 deg. 50'24" W. Coll.: U.S. Grant and party, 1909, field No. G673. [Seldovia 1:250,000 quadrangle; Peninsular terrane](description from Silberling et al., 1997, p. 18)
Halobia dilitata
61 of G.C. Martin, 1911 (Mesozoic loc. 7234) , Seldovia , Kenai Peninsula, southern Alaska; south shore of Port Graham, 1 and 2/5 miles below wharf. Coll.: G.C. Martin, June 28, 1911, field No. Station 61 [Seldovia 1:250,000 quadrangle; Peninsular terrane](description from Silberling et al., 1977, p. 18)
Monotis (Pacimonotis) subcircularis
1507 of Blackwelder, 1915 (Mesozoic loc. 9382) , Charley River , Yukon River, central Alaska; south bank, southwest of Nation. Coll.: Eliott Blackwelder, June 20, 1915; field No. 1507. [Charley River 1:250,000 quadrangle; in rocks not included among the Phanerozoic accretionary terranes] (description from Silberling et al., 1997, p. 18)
Monotis (Pacimonotis) ?subcircularis
43 of F.H. Moffit, 1916 (Mesozoic loc. 9961) , Mc Carthy , Wrangell Mountains, southern Alaska; Mill Creek tributary to Lakina River on west side near forks of creek, 2 1/2 miles from Lakina River; from float in gulch below cliff. Coll.: F.H. Moffit, field No. 43, Sept. 3, 1916. [McCarthy 1:250,000 quadrangle; Wrangellia terrane](description from Silberling et al., 1997, p. 18)
Monotis (Monotis) alaskana
18-G-90 (Mesozoic loc. 10546) , Seldovia , Cook Inlet, Kenai Peninsula, southern Alaska; northerly shore of Port Graham near mouth of small stream northeast of cannery, south shore of Kachemak Bay. Coll. A.C. Gill, July 20, 1918, field No. 18-G-90. [Seldovia 1:250,000 quadrangle; Peninsular terrane](description from Silberling et al., 1997, p. 18)
Monotis (Monotis) alaskana
43ACa39 (Mesozoic loc. 18927) , Taylor Mts , W.M. Cady, 1943. Seven miles south of Flat Top Mountain, crest of spur of ridge east of Cinnabar Creek, about 1 mile northwest of mouth of creek. Coquina of Monotis subcircularis (Gabb); from upper Triassic, "Noric stage". (description from Cady et al., 1955); Silberling et al., 1997, p. 18 provide following description: "Kuskokwim Mountains, southwestern Alaska; 34 miles S. 73 deg. W. of Kashegelok on crest of spur of ridge east of Cinnabar Creek at a point about 1 miles N. 60 deg. W. of the mouth of the creek. Coll.: W.M. Cady, 1943, field No. 43ACa39 [Taylor Mountain 1:250,000 quadrangle; Togiak terrane]; [Lat. 60.7700, Long. 158.8127 coquina-siltstone (description from Karl et al., 2011)]; Grant-Mackie and Silberling, 1990, p. 253, provide the following data: "USGS Mesozoic loc. 18927. Kuskokwim Mountains, southwestern Alaska; 34 miles S. 73°W. of Kashegelok on crest of spur of ridge east of Cinnabar Creek at a point about 1 mile (1.6 km) N. 60°W. of the mouth of the creek. Coll.: W. M. Cady, 1943, field no. 43ACa39. Taylor Mountain 1:250,000 quadrangle. Togiak terrane."
Monotis
50AHr590 (Mesozoic loc. 23170) , Goodnews Bay , 15 1/2 miles S. 48 deg. W. of outlet of Kagati Lake; 11 1/2 miles S. 70 deg. E. of mouth of Klak Creek; 15 3/4 miles N. 6 1/2 deg. E. of head of Goodnews Lake. Fossils occur near the southeast end of a ridge which lies north of a lake about 2 miles long which drains into Klak Creek. The ridge starts about the center of the lake and extends northwestward. Fossil in float about 900 feet above lake level and 20 feet below the crest of the ridge. Lithology of beds (from transmittal sheet of Hoare): Fossils occur in float derived from well-bedded vari-colored cherts and tuffs. The lithology appears to be similar to that described above under 50AHr364-A. [Silberling et al., 1997, p. 18-19 provide following description: Kuskokwim region, southwestern Alaska; lat 59 deg. 44'02" N., long 160 deg. 27'02" W.; 15 1/2 miles S. 48 deg. W. of outlet of Kagati Lake; 11 1/2 miles S. 70 deg. E. of mouth of Klak Creek; 15 3/4 miles N., 6 1/2 miles E. of head of Good News Lake. Fossils occur near the southeast end of a ridge that lies north of a lake about 2 miles long that drains into Klak Creek; the ridge starts about the center of the lake and extends northwestward; fossils in float about 900 feet above lake level and 20 feet below the crest of the ridge. Coll.: J.M. Hoare, August 18, 1950, field No. 50AHr590. Recollected by W.L. Coonrad and J.M. Hoare, 1975, field No. GC4-1122; Goodnews C-4 quadrangle; NE 1/4 sec. 23, T. 5 S., R. 66 W. [Goodnews terrane]]
Monotis (Entomonotis) ochotica ss
49ALac118F (Mesozoic loc. 24504) , Killik River , Colville rgion, northern Alaska; west side of Killik River, 12 miles north of junction with Easter Creek. Coll.: M.C. Lachenbruch, 1949, field No. 49ALac118F [Killik River 1:250,000 quadrangle; Endicott Mountains or DeLong Mountains subterrane of the Arctic Alaska terrane](description from Silberling et al., 1997, p. 19)
Monotis (Pacimonotis) subcircularis
78AHr146 (Mesozoic loc. D10708) , Dillingham , Lat. 59 deg. 53.1 min. N., Longitude 158 deg. 55.5 min. W.: sec. 28, T. 3 S., R. 56 W. Limestone within thick section of graywacke and shale; small outcrop on south shore of Nuyakuk Lake about 0.5 km east of obvious promontory. [Silberling et al., 1997, p. 19 provide same locality data, but not that this locality is in Togiak(?) terrane]
75AMu57 (Mesozoic locs. D11071, D11072, D11073, D11074, D11075, D11076, D11077, D11078, D11079, D11080, D11081, D11082, D11083, D11084, D11085, D11086, D11087, D11088, D11089, D11090, D11091, D11092, D11093, D11094, D11095, D11096, D11097, D11098, D11099, D11100, D11101, D11102, D11103, D11104, D11105, D11106) , Killik River , Section located on bluff on east bank of Otuk Creek; sec. 31, T. 10 S., R. 16 W.
91ACy-7 (Mesozoic loc. D13388) , Seldovia , Port Graham region, southern Alaska: north shore of Port Graham, south of Selenie Lagoon, lat 59°22.07' N., long 151°51.15' W. Coll.: Béla Csejtey, 1991, field no. 91AC7-7. [Seldovia B-5 quadrangle; Peninsular terrane] (description from Silberling et al., 1997, p. 19)
Steinmannites
80-S-382 (Mesozoic loc. D11287) , Talkeetna , Talkeetna region, southern Alaska; Monotis and Halobia from single 10 cm concretionary beds; Inoceramus? and belemnites from adjoining 1-2 m of section; few tens of meters above top of pillow basalt. Coll. N.J. Silberling, 1980, field No. 80-S-382. Talkeetna C-6 quadrangle (center E edge, NE1/4 sec. 14, T. 30 N., R. 19 W.). [McKinley terrane] (description from Silberling et al., 1997, p. 19)
Halobia cf. H. fallax
Monotis (Eomonotis) pinensis?
80ADt170 (Mesozoic loc. D11289) , Karluk , Alaska Peninsula, southwestern Alaska; Karluk C-4 and C-5 quadrangle; limestone 2 miles N. 81° E. of VABM Kek; lat. 57°44'30" N., long 155°17'20" W. Coll.: R.L. Detterman, 1980, field No. 80ADt170. [Peninsular terrane] (description from Silberling et al., 1997, p. 19); Grant-Mackie and Silberling, 1990, p. 253 provide following data: "USGS Mesozoic loc. D 11289. Alaska Peninsula, southwestern Alaska; Karluk C-4 and C-5 quadrangle; limestone 2 miles (3.2 km) N. 81°E. of VABM Kek (elev. 365 m); lat. 57°44'30"N., long. 155°17'20"W. Coll.: R. L. Detterman, 1980, field no. 80ADt 170. Peninsular terrane."
Monotis (Monotis) alaskana
77-S-152 (Mesozoic loc. D12569) , Healy , Talkeetna Mountains, southern Alaska; Healy A-5 quadrangle; float from interbedded tuffaceous sedimentary rocks and basalt; center S 1/2 NW 1/4 sec. 24, T. 20 S., R. 9 W. Coll.: N.J. Silberling, 1977, field No. 77S152 [Susitna terrane] (description from Silberling et al., 1997, p. 19); Grant-Mackie and Silberling, 1990, p. 253 provide the following data: "USGS Mesozoic loc. D12569. Talkeetna Mountains, southern Alaska; Healy A-5 quadrangle; float from interbedded tuffaceous sedimentary rocks and basalt; center S1/2NW/4 sec. 24, T20S, R9W. Coll.: N. J. Silberling, 1977, field no. 77S152. Susitna terrane."
Monotis (Monotis) alaskana
Monotis (P.) ?subcircularis
ADB-123F (Mesozoic loc. M749) , Karluk , Alaska Peninsula, southwestern Alaska; on coast near point between Cape Kekurnoi and Puale Bay about 1/2 mile NE. from the cabin near VABM 96 on Karluk 1:250,000 quadrangle; Monotis occurs about 400 feet above base(?) of Triassic section and 250-300 feet above coralline limestone that rests on Permian(?). Coll.: M.C. Lachenbruch, 1959, field No. ADB-123F. [Karluk 1:250,000 quadrangle; Peninsular terrane] (description from Silberling et al., 1997, p. 19); Grant-Mackie and Silberling, 1990, p. 254 provide the following data: USGS Mesozoic loc. M749. Alaska Peninsula, southwestern Alaska; on coast near point between Cape Kekurnoi and Puale Bay; about 0.5 mile (800 m) northeast from cabin near VABM 96 on Karluk 1:250,000 quadrangle. Coll.: M. C. Lachenbruch, Gulf Oil Co., 1959, field no. ADB-123F. Peninsular terrane."
Monotis (Pacimonotis) subcircularis
62-49 (Mesozoic loc. M1690) , Mc Carthy , Wrangell Mountains, southern Alaska; nose of spur between head of East Ford Creek and "Anticline Valley"; 280 feet above base of McCarthy Formation, measured by Abney level; McCarthy C-5 quadrangle, central E 1/2 sec. 16, T. 4 S., R. 15 E. Coll.: N.J. Silberling, July 11, 1962, field No. 62-49. [Wrangellia terrane] (description from Silberling et al., 1997, p. 20)
Monotis (Pacimonotis) subcircularis
62-20 (Mesozoic loc. M1691) , Mc Carthy , Wrangell Mountains, southern Alaska; nose of spur between head of East Fork Creek and "Anticline Valley"; 310 feet above base of McCarthy Formation, measured by Abney level; McCarthy C-5 quadrangle, central E 1/2 sec. 16, T. 4 S., R. 15 E. Coll.: N.J. Silberling and R.W. Imlay, July 11, 1962, field No. 62-20. [Wrangellia terrane] (description from Silberling et al., 1997, p. 20)
Monotis (Pacimonotis) subcircularis
62-21 of N.J. Silberling, 1962 (Mesozoic loc. M1692) , Mc Carthy , Wrangell Mountains, southern Alaska; McCarthy C-5 1:63,360 quadrangle; nose of spur between head of East Fork Creek and "Anticline Valley"; center E 1/2 sec. 16, T. 4 S., R. 15 E.; 415 feet above base of the McCarthy Formation. Coll.: N.J. Silberling, 1962, field No. 62-21. [Wrangellia terrane] (description from Silberling et al., 1997, p. 20); [USGS Mesozoic loc. M1692. Wrangell Mountains, southern Alaska; McCarthy C-5 1:63,360 quadrangle; nose of spur between head of East Fork Creek and Anticline Valley; center E1/2 sec. 16, T4S, R15E; 415 ft (125 m) above base of McCarthy Formation. Coll.: N. J. Silberling, 1962, field no. 62-21. Wrangellia terrane. (description of Grant-Mackie and Silberling, 1990, p. 254)]
Monotis (Monotis) alaskana
62-22 of N.J. Silberling, 1962 (Mesozoic loc. M1693) , Mc Carthy , Same as for locality M1692, but 475 feet above base of the McCarthy Formation. Coll.: N.J. Silberling, 1962, field No. 66-22. [Wrangellia terrane] (description from Silberling et al., 1997, p. 20); [USGS Mesozoic loc. M1693. Same as for loc. M1692, but 475 ft (145 m) above base of McCarthy Formation. Coll.: N. J. Silberling, 1962, field no. 62-22. (description from p. 254 of Grant-Mackie and Silberling, 1990)]
Monotis (Monotis) ?haueri
62-24 of Silberling, 1962 (Mesozoic loc. M1700) , Mc Carthy , Wrangell Mountains, southern Alaska; McCarthy C-4 1:63,360 quadrangle; collection from single bed about 70 feet below top of cliff-forming unit in lower part of McCarthy Formation on S. side of Monotis Creek alongside lower rock glacier; lat. 61° 32.10' N., long. 142° 25.75' W. Coll.: N.J. Silberling, 1962, field No. 62-24. [Wrangellia terrane] (description from Silberling et al., 1997, p. 20); [USGS Mesozoic loc. M1700. Wrangell Mountains, southern Alaska; McCarthy C-4 1:63,360 quadrangle; collection from single bed about 70 ft (21 m) below top of cliff-forming unit in lower part of McCarthy Formation on south side of Monotis Creek alongside lower rock glacier; lat. 61°32.10'N., long. 142°25.75'W. Coll.: N. J. Silberling, 1962, field no. 62-24. Wrangellia terrane. (description from Grant-Mackie and Silberling, 1990, p. 254)]
Monotis (Monotis) ?alaskana
62-25 (Mesozoic loc. M1701) , Mc Carthy , Same as for M1700, but from single bed about 10 feet stratigraphically lower. Coll.: N.J. Silberling, 1962, field No. 62-25.
Monotis (Eomonotis) jakutica
Monotis (Pacimonotis) ? subcircularis
Monotis (Pacimonotis) subcircularis
ROC 1113 (Stanford Univ. loc. SU 3652) , Karluk , Alaska Peninsula, southwestern Alaska; Karluk C-4 and C-5 1:63,360 quadrangle; east side of Puale Bay about 2,300 feet N. 40° W. of VABM Hike. Coll.: W.T. Rothwell, Jr., 1962, field No. ROC 1113. [Peninsular terrane] (description from Silberling et al., 1997, p. 21); [tanford Univ. loc. SU3652. Alaska Peninsula, southwestern Alaska; Karluk C-4 and C-5 1:63,360 quadrangle; east side of Puale Bay about 2,300 ft (700 m) N. 40°W. of VABM Hike. Coll.: W. T. Rothwell, 1962, field no. ROC 1113. Peninsular terrane. (description from Grant-Mackie and Silberling, 1990, p. 254)]
Monotis (Monotis) alaskana
60ABa732 (USGS Mesozoic locality M1020) , Charley River , About 7 miles south of mouth of Nation River, along west bank of Trout Creek opposite mouth of tributary from east. Coordinates (8.9, 6.2). (description from Silberling E&R report); Upper Yukon, east-central Alaska; Charley River A-2 1:63,360 quadrangle; about 7 miles south of mouth of Nation River; west banks of Trout Creek opposite mouth of tributary from east; lat 65°05.3' N., long 141°41.7' W. Coll.: E.E. Brabb, 1960, field No. 60ABa732. [In rocks not included among the Phanerozoic accretionary terranes] (description from Silberling et al., 1997, p. 19-20); Grant-Mackie and Silberling, 1990, p. 254, provides the following: " USGS Mesozoic loc. M1020. Upper Yukon, east-central Alaska; Charley River A-2 1:63,360 quadrangle; about 7 miles (11.3 km) south of mouth of Nation River; west bank of Trout Creek opposite mouth of tributary from east; lat. 65°05.3'N., long. 141°41.7'W. Coll.: E. E. Brabb, 1960, field no. 60ABa732. Ancestral North America (i.e., rocks not regarded as an accreted terrane).'
Monotis (Eomonotis) daonelliformis
62-9 of N.J. Silberling, 1962 (Mesozoic loc. M1714) , Charley River , Upper Yukon region, east-central Alaska; Charley River A-2 1:63,360 quadrangle; black paper shale several tens of feet above Trout Creek on its west side; center NE 1/4 NW 1/4 SW 1/4 sec. 17, T. 3 N., R. 30 E. Coll.: N.J. Silberling, 1962, field No. 62-9. [In rocks not included among the Phanerozoic accretionary terranes] (description from Silberling et al., 1997, p. 20); [USGS Mesozoic loc. M1714. Upper Yukon, east-central Alaska; Charley River A-2 1:63,360 quadrangle; black papery shale several tens of feet above Trout Creek on its west side; center NE1/4NW1/4SW1/4 sec. 17, T3N, R30E. Coll.: N. J. Silberling, 1962, field no. 62-9. Ancestral North America. (description from Grant-Mackie and Silberling, 1990, p. 254)
Monotis (Eodaonella) daonelliformis
Halobia fallax
62-8 (Mesozoic loc. M1715) , Charley River , Upper Yukon region, east-central Alaska; same general locality as M1714, but 10-30 feet stratigraphically higher; lenticular gray-brown limestone beds more or less equivalent to M1716. Coll.: N.J. Silberling, field No. 62-8. [In rocks not included among the Phanerozoic accretionary terranes] (description from Silberling et al., 1997, p. 20)
Monotis (Eomonotis) ?pinensis
?Himavatites cf. H. multiauritis
62-4 (Mesozoic loc. M1716) , Charley River , Upper Yukon region, east-central Alaska; farthest upstream of pre-Tertiary outcrops; west bank of Trout Creek at water line; dark bituminous papery calcareous shale with Monotis upstream from, but more or less stratigraphically equivalent to, M1715; Charley River A-2 quadarngle, SE 1/4 NE 1/4NW1/4 SW 1/4 sec. 17, T. 3 N., R. 30 E. Coll.: N.J. Silberling, June 29, 1962, field No. 62-4. [In rocks not included among the Phanerozoic accretionary terranes] (description from Silberling et al., 1997, p. 20-21)
Monotis (Eomonotis) ?pinensis
Neohimavatites cf. N. canadensis
63ACn2781D (Mesozoic loc. M2143) , Charley River , East-central Alaska; collections from traverse taped in N. 45° W. direction along SW. bank of Yukon River beginning 835 feet N. 50° W. from rocky point formed of the Tahkandit Limestone; about 6 feet of calcareous shale beginning at 27 feet traverse distance above base of section; lat 65°11.1' N., long 141°42.3' W. Coll.: M. Churkin, 1963, field No. 63ACn2781D. [Charley River A-2 quadrangle; in rocks not included among the Phanerozoic accretionary terranes] (description from Silberling et al., 1997, p. 20)
Monotis (Pacimonotis) ?subcircularis
No Data (Mesozoic loc. 10168) , Sitka , Admiralty Island, southeastern Alaska; west side of Mole Harbor. Coll.: Edwin Kirk, August 18, 1918. [Sitka 1:250,000 quadrangle; Peninsular terrane](description from Silberling et al., 1997, p. 18) [Note by R.B. Blodgett, the assignment to the Peninsular terrane is incorrect, should be Alexander terrane]
Monotis (Monotis) alaskana
80S431 (Mesozoic loc. D11284) , Medfra , Kuskokwim Mountains, west-central Alaska; Medfra C-3 1:63,360 quadrangle; float from narrow strip of rubble on south side of ridge; center E 1/2 SE 1/4 sec. 12, T. 22 S., R. 24 E. Coll.: N.J. Silberling, and others, 1980, field No. 80S431. [Nixon Fork terrane] (description from Silberling et al., 1997, p. 19); Grant-Mackie and Silberling, 1990, p. 253 give following data: "USGS Mesozoic loc. D11284. Kuskokwim Mountains, west-central Alaska; Medfra C-3 1:63,360 quadrangle; float from narrow strip of rubble on south side of ridge; center E1/2SE1/4 sec. 12, T22S, R24E. Coll.: N. J. Silberling and others, 1980, field no. 80S431. Nixon Fork terrane."
Monotis (Eomonotis) ?typica
Monotis (Eomonotis) jakutica
Monotis (Monotis) sp indet.
80S432 (Mesozoic loc. D11285) , Medfra , Same locality as D11884 but bedrock on north side of ridge and 4-5 m stratigraphically higher. Coll.: N.J. Silberling, 1980, field No. 80-S-432. (description from Silberling et al., 1997, p. 19)
Monotis (Pacimonotis) subcircularis
80S436 (Mesozoic loc. D11286) , Medfra , Kuskokwim Mountains, west-central Alaska; Medfra C-3 1:63,360 quadrangle; bedrock on ridge crest a few tens of meters stratigraphically above float of middle Norian Halobia and several meters below float of Monotis (P.) subcircularis and Heterastridium; SE1/4 NW1/4 sec. 2, T. 22 S., R. 24 E. Coll.: N.J. Silberling, 1980, field No. 80S436. [Nixon Fork terrane] (description from Silberling et al., 1997, p. 19); Grant-Mackie and Silberling, 1990, provide following data: "USGS Mesozoic loc. D11286. Kuskokwim Mountains, west-central Alaska; Medfra C-3 1:63,360 quadrangle; bedrock on ridge crest a few tens of meters stratigraphically above float of middle Norian Halobia and several meters below float of Monotis subcircularis; SE1/4NW1/4 sec. 2, T22S, R24E. Coll.: N. J. Silberling, 1980, field no. 80S436. Nixon Fork terrane."
Monotis (Eomonotis) anjuensis