Chulitnacula, a New Paleobiogeographically Distinctive Gastropod Genus from Upper Triassic Strata in Accreted Terranes of Southern Alaska

Journal of the Czech Geological Society 46/1ñ2(2001) 213

Chulitnacula, a new paleobiogeographically distinctive gastropod genus from Upper Triassic strata in accreted terranes of southern Alaska

(3 figs)

JIÿÕ FR›DA 1 ñ ROBERT B. BLODGETT 2

1 Czech Geological Survey, Kl·rov 3, 118 21 Praha 1, Czech Republic; e-mail: [email protected] 2 Department of Zoology, Oregon State University, Corvallis, Oregon, 97331 USA; e-mail: [email protected]

A new protorculid gastropod genus, Chulitnacula, is based on Protorcula alaskana Smith, 1927, from the Chulitna terrane of south- central Alaska. The type species also occurs in two other accreted terranes of southern Alaska: 1.) in the Farewell terrane (Nixon Fork subterrane) of southwestern Alaska; and 2.) in the Alexander terrane of southeastern Alaska. This taxon is a common to dominant element in shallow-water, near-shore late Norian age strata of all of these terranes. It appears to be biogeographically significant in that while it so abundant in these southern Alaskan accreted terranes, it is completely unknown elsewhere in Upper Triassic para-autochthonous rocks of western North America (i.e. Nevada, Sonora). The occurrence of Chulitnacula alaskana (Smith, 1927) in the Chulitna, Farewell (Nixon Fork subterrane) and Alexander terranes suggests that they were in close reproductive communication in the Late Triassic. The absence of this taxon in either the Wrangellia terrane of southern Alaska and British Columbia, as well as in the related Wallowa terrane of northeastern Oregon and adjacent western Idaho is worthy of note. This absence plus many other major differences in their respective Late Triassic gastropod faunas indicate that the Chulitna-Farewell-Alexander terrane association was far removed from the Wrangellia-Wallowa terrane couplet. While both faunal associations are characteristically tropical in aspect, their biogeographically differing faunas indicate that they were probably very distantly separated from one another in the Panthalassa Ocean at this time.

Key words: Triassic, Gastropoda, Alaska, Chulitna terrane, Farewell terrane, Alexander terrane, new taxa

Introduction this species are deposited in the University of Alaska Museum (UAM) in Fairbanks, Alaska, USA and in the On-going study by the two authors of Upper Triassic gas- Geological Survey (Prague), Ji¯Ì Fr˝da collection (CG⁄ tropod biogeography of western North America has re- JP). vealed a number of biogeographically significant gastropod taxa from different accreted terranes comprising the Paleobiogeographic significance western margin of the North American continent. Our pur- pose here is to demonstrate the utility of Upper Triassic The State of Alaska is for the greater part composed of gastropods as a tool in paleobiogeographic analysis of a number of tectonostratigraphic terranes (also referred accreted terranes. Although previously poorly known from to as accreted terranes, lithotectonic terranes, etc.), which western North America (the only described faunas are to have emplaced by means of sea-floor spreading and tran- be found in Smith 1927 ñ Erwin 1994), this group holds scurrent fault movements long distances from their pre- great potential for biogeographic studies due to the fact vious points of origin. The only exception to this is the that this molluscan class is well represented in faunas of roughly triangular portion of Alaska (Fig. 1), bounded these terranes. In addition, due to the very restricted na- on the northwest by the Porcupine River and to south- ture of larval distribution in certain gastropod groups, west by the Yukon River. The latter region represents the great potential exists for the fine delineation of low-level western terminus of the Paleozoic-Triassic North Amer- paleobiogeographic units. This has been more than ade- ican continental margin. A number of differing terrane quately exemplified by our earlier studies of Paleozoic nomenclatures exists for Alaska (contrast Coney et al. gastropod biogeography (Blodgett 1992; Blodgett et al. 1980 with Jones et al. 1987 and Nokleberg et al. 1994). 1988, 1990, 1999; Blodgett ñ Fr˝da 1999; Fr˝da ñ Rohr Triassic rocks from southern Alaskaís accreted terranes 1999). In this paper we draw attention to a Norian gas- contain thick carbonate successions with tropical marine tropod species, Chulitnacula alaskana (Smith, 1927), faunas, in contrast to the much cooler-water Triassic fau- which characterizes near-shore, shallow-water marine nas associated with the North American portion of Alas- strata of several accreted terranes (Chulitna, Farewell, and ka (lower part of the Glenn Shale of east-central Alas- Alexander terranes) of southern Alaska (Fig. 1). In addi- ka) and from the Shublik and Otuk formations of the tion to indicating close spatial relationships between these Arctic Alaska terrane of northern Alaska. Determination three terranes within the Panthalassa Ocean during Late of probable Triassic paleolatitudes of the southern Alas- Triassic time, this species is also important taxonomical- kan terranes has been the subject of many studies (Pa- ly because it represents a new genus of the Protorculidae, nuska ñ Stone 1985; Hillhouse 1977, Hillhouse ñ Grom- which appears to include several related species in the mÈ 1980, 1984; Stone 1982; Haeussler et al. 1992), many eastern Tethys region. The newly illustrated specimens of of which are contradictory to one another. Although these 214 Journal of the Czech Geological Society 46/1ñ2(2001)

C o o P h o u 170 150 130 e k n o i n t s s Canada Basin k u l a

Chulitna terrane Precambrian o shield 170 Eas g fault t lim Kalta it o f

Farewell r

Den i

o a l

l l e

60 terrane i f

a r u a

l Wrangellia

t n

o r Alexander m Fig. 1. Generalized map

terrane t i showing location of the Fa- o n rewell, Chulitna, Alexander, and Wrangellia terranes in T in southern Alaska and nor- t t in us a thwestern Canada (modified thr ega fa Aleutian m u from Coney et al., 1980). lt Lined pattern ñ North Ameri- can autochthonous basement. Wrangellia Chulitnacula occurrences: 1 ñ Nixon Fork subterrane of Q u Farewell terrane (Taylor e e o PACIFIC PLATE n Mountains D-3 quadrange); C 50 ha 2 ñ Chulitna terrane (Healy rlo tte A-6 quadrangle); 3 ñ Alexan- f 500 km aul der terrane (Port Alexander t D-1 quadrangle). accreted terranes have diverse, rich fossil Upper Trias- succession of dominantly shallow-water carbonate rocks. sic biotas, relatively little is known of their contained fau- Triassic strata are recognized in only two areas within nas with the exception of few groups such as the flat the subterrane, one in the northern part in the Medfra C-3 clams (Silberling 1985, Silberling et al. 1997, Grant- 1:63,360-scale quadrangle, and the other in southernmost Mackie ñ Silberling 1990), bivalves in general (Newton part of the subterrane in the Taylor Mountains D-2 and 1983) and corals (Stanley 1979; Montanaro Gallitelli D-3 quadrangles (Blodgett et al. 2000, McRoberts ñ et al. 1979). In these paper our attention is focused on Blodgett, in press). the biogeographic significance of one species of gastro- This species is also very abundant in late Norian strata pod, Chulitnacula alaskana (Smith, 1927), from three of the Chulitna terrane (its type area) of south-central Alas- separate terranes (Chulitna, Farewell, and Alexander ter- ka (Fig. 1). This terrane is characterized by a distinctive ranes) of southern Alaska. succession of Upper Devonian ophiolitic rocks; upper Pa- The Farewell terrane of southwestern Alaska (Fig. 1) leozoic chert, tuff, volcanic conglomerate and sandstone, was established by Decker et al. (1994) to include three flysch, and limestone; Triassic limestone, basalt, redbeds, previously defined terranes (Nixon Fork, Dillinger, and sandstone and shale; and Jurassic argillite, sandstone, and Mystic), which were recognized to be genetically relat- chert (Jones et al. 1980). The presence of a thick redbed ed to one another. The latter were all reduced in rank to unit within the Triassic succession, containing late Nori- being subterranes of the Farewell terrane. The Farewell an fossils in uppermost strata, has been frequently cited terrane has recently been interpreted to represent a rift- as evidence for a more southerly origin of this terrane dur- ed continental margin sequence derived from the Siberi- ing Triassic time (i.e., Jones et al. 1980, 1982). Ammo- an paleocontinent (Blodgett ñ Brease 1997; Blodgett nites from a Lower Triassic limestone unit also indicate a 1998; Blodgett ñ Boucot 1999). Chulitnacula alaskana more southerly origin for this terrane (Nichols ñ Silber- (Smith, 1927) is found in Norian strata of the Nixon Fork ling 1979). Norian age gastropods are especially common subterrane of the Farewell terrane in the Taylor Moun- in transitional strata between the Trrb unit and overlying tains D-3 1:63,360-scale quadrangle. The Nixon Fork JTrs unit of Jones et al. (1980) in the southern part of the subterrane is characterized by a succession of strata rang- Healy A-6 1:63,360 scale quadrangle. Chulitnacula alas- ing in age from Neoproterozoic to Triassic, with the kana (Smith, 1927) is the most abundant gastropod in three Neoproterozoic-Devonian portion representing a thick collections made in 1997 from these two units by mem- Journal of the Czech Geological Society 46/1ñ2(2001) 215 bers of the Alaska Divison of Geological & Geophysical Coelostylinidae to belong to the Loxonematoidea, and Surveys during mapping of this quadrangle. placed additional gastropod genera in this family, extend- Chulitnacula alaskana (Smith, 1927) is also present ing its stratigraphic range from the Devonian to the Ju- in late Norian strata of the Alexander terrane of south- rassic. Knight et al. (1960) briefly discussed the family- eastern Alaska (Fig. 1). This terrane includes a variety level classification of Loxonematoidea. These authors of rocks of latest Precambrian? to Middle(?) Jurassic age divided the Loxonematoidea into four families: Loxone- (Gehrels ñ Berg 1994). The Alexander terrane, like the matidae, Palaeozygopleuridae, Pseudozygopleuridae, and Farewell and Arctic Alaska terranes of Alaska, is also Zygopleuridae; but they did not recognize the family considered to be of Siberian origin on the basis of its dis- Coelostylinidae within this superfamily. Bandel (1991) tinctive Silurian-Devonian megafauna (Blodgett ñ Bou- established new family Protorculidae based on the genus cot 1999). In recent years it has been suggested that the Protorcula Kittl, 1894. This family (uniting Protorcula Alexander terrane and the Wrangellia terrane are part of and Ampezzopleura Bandel 1991) was placed by Bandel larger tectonostratigraphic entity termed the Wrangellia (1991) together with the families Zygopleuridae Wenz, superterrane or Wrangellia composite terrane (Nokleberg 1938 and Pseudozygopleuridae Knight, 1930 into his et al. 1994; Plafker ñ Berg, 1994; respectively). We find new superfamily Zygopleuroidea. N¸tzel (1998) noted the unification of the Alexander terrane (in its type area the paraphyly of the Zygopleuroidea and considered the in the Alexander Archipelago) with Wrangellia during the Protorculidae to be an extinct sister-group of the mod- Late Triassic untenable on the basis of both the quite dif- ern Cerithiopsoidea and Triphoroidea. N¸tzel also fering Triassic stratigraphies and accompaning Triassic changed the generic content of the family Protorculidae. gastropod faunas between the Alexander terrane (as ex- The Triassic genus Ampezzopleura Bandel, 1991 was pressed in the Keku Straits region between Kuiu and transferred by him from the Protorculidae to the Zy- Kupreanof islands) and the Wrangellia terrane (see also gopleuridae as the genotype of a new subfamily Ampez- Blodgett et al. 2001, this volume). zopleurinae N¸tzel, 1998, which also included the Tri- The genus Chulitnacula is unknown in either of the assic genus Striazyga N¸tzel, 1998. On the other hand, two major Late Triassic gastropod collections we have N¸tzel (1998) added several genera to the Protorculidae, examined from the Wallowa (Spring Creek locality in including his new Triassic genus Atorcula and Jurassic Hells Canyon) and Wrangellia (Green Butte locality in genus Acanthostrophia Conti and Fischer, 1982. N¸tzel the Wrangell Mountains) terranes, as well as from the also placed with some doubt the Permian genus Prodio- richly diverse late Norian ìLewiston faunaî (belonging zoptyxis Batten, 1985 and the Triassic genus Undularia to the Wallowa terrane) from the Lapwai Indian Reser- Koken, 1892 in the Protorculidae. Later N¸tzel and Se- vation in Idaho (Alexander N¸tzel, written communica- nowbari-Daryan (1999) placed two additional Triassic tion, 2001). The abundant presence of Chulitnacula alas- genera, Moerkeia Bˆhm, 1895 and Anulifera Zapfe, 1962 kana (Smith, 1927) in the three previously mentioned in the family Protorculidae. Alaskan terranes (Chulitna, Farewell, and Alexander terrane), compared with its absence in certain other accreted Chulitnacula gen. nov. terranes (Wrangellia and Wallowa terranes) of western North America, suggest that Chulitna-Farewell-Alexander Type species: Protorcula alaskana Smith, 1927 from Norian stra- terrane assemblage was probably separated by a repro- ta of the Chulitna district (Chulitna terrane), Healy A-6 1:63,360- scale quadrangle, south-central Alaska. ductively significant distance from the Wrangellia-Wal- Etymology: According to both the geographic feature (Chulitna lowa terrane couplet in differing tropical areas within the River) and the tectonostratigraphic terrane (Chulitna terrane). Panthalassa Ocean. We use the term assemblage here to indicate that these three terranes were close enough to Diagnosis: Medium-sized protorculid with prominent one another during Late Triassic time to share similar keel forming angulated whorl profile; keel situated low faunas, and not that they were amalgamated with one on whorl surface, about one-fourth of whorl height above another at this time. The separation of these terrane lower suture (Figs 2, 3); whorl profile above keel con- groupings is also supported by the overall faunal differ- cave; keel bears a row of prominent nodes, varying in ences shown by most other gastropod groups that we number from 15 to 18 per one volution in adult whorls; have studied from these terranes. whorl side as well as shell base ornamented by numerous spiral threads; growth lines form a distinct wide Systematic paleontology U-shaped arch between keel and upper suture (Fig. 2.4), culminating at about one-fourth of whorl height below Subclass Caenogastropoda Cox, 1960 upper suture; growth lines below are opisthocline, cross- Order Ptenoglossa Gray, 1853 ing the keel, to reach the lower suture; shell structure and Family Protorculidae Bandel, 1991 protoconch unknown. Comparison: The new genus is most similar to the Remarks: Cossmann (1909) placed Protorcula Kittl, genera Protorcula Kittl, 1894 and Moerkeia Bˆhm, 1895. 1894 in his family Coelostylinidae. This opinion was also The type species of Chulitnacula, Protorcula alaskana followed by Wenz (1938), who considered the family Smith, 1927, had been placed in the former genus by 216 Journal of the Czech Geological Society 46/1ñ2(2001)

1 2 4

Fig. 2. Chulitnacula alaskana (Smith, 1927) from Healy A-6 quadrangle, south-central Alaska (Chulitna terrane); 1 ñ side view, UAM 2630; 2 ñ side view, UAM 2631; 3 ñ side view of final whorl, UAM 2632; 4 ñ side view of single whorl showing growth lines forming a distinct U-shaped apertural sinus, CGU JF785; all specimens from locality 151 of Blodgett ñ Clautice, 2000 (=field locality 97AM241 of Marti Miller); all views x3.

Smith (1927) and recently questionably transferred to tion needs further study. Chulitnacula may be distin- Moerkeia by N¸tzel ñ Senowbari-Daryan (1999). Chu- guished from the protorculid genus Atorcula N¸tzel, litnacula differs from Protorcula in having a different 1998, by its angular whorl profile and shell ornamenta- whorl profile of the teleoconch and by the absence of an tion. Teleoconchs of all known species of Atorcula, in- upper spiral keel. In the latter genus, the whorl profile cluding its type species, lack any angulation and the ex- is concave between sutures and two distinctive nodose ternal surface of teleoconch whorls is smooth (see N¸tzel rows are developed, one close to the upper and other 1998, Pl. 26). The same shell features differentiates Chu- close to the lower suture, respectively (Zardini 1985, litnacula from the type species of the protorculid genus Pl. 4, Figs 17, 18a, b N¸tzel 1998, Pl. 27, Figs AñE). On Undularia Koken, 1892, based on the Middle Triassic the other hand, in Chulitnacula the whorl profile between Undularia scalata (Schlotheim) from the Muschelkalk of the sutures is strongly angulated by a prominent keel Germany. Chulitnacula also resembles the protorculid bearing nodes. This keel is situated low on the whorl, genus Anulifera Zapfe, 1962, in its fine spiral ornamen- about one-fourth of whorl height above lower suture. The tation as well as by the presence of a nodose spiral row suture in Protorcula lies between two distinct spiral rows situated low on the whorls of the teleoconch. However, bearing nodes, but such shell features close to the sutures the distinctly concave upper whorl side easily distin- are not present in Chulitnacula. In contrast, no nodose guishes Chulitnacula. The whorl side between the sutures row close to the upper suture is developed in Chulitnac- in both known species of Anulifera is straight or very ula. The external shell surface of Chulitnacula is orna- slightly convex, but is distinctly angular in Chulitnacu- mented by numerous fine spiral threads (Figs 2, 3), but la. The Permian genus Prodiozoptyxis Batten, 1985, rep- in Protorcula it is smooth or ornamented by very weak resenting probably the oldest protorculid genus (N¸tzel spiral threads. 1998), has two prominent angulations on its shell, one Chulitnacula gen. nov. differs from the type species close to upper suture and the other close to lower suture of Moerkeia by its much higher spire, the absence of an (see Batten 1985, Figs 46ñ48). This shell feature distin- umbilicus and the presence of spiral ornamentation. The guishes it from the new Triassic genus Chulitnacula. genus Moerkeia Bˆhm, 1895 is based on Angularia prae- Discussion: The unknown nature of the protoconch fecta Kittl, 1894 from the southern Alps of Italy. Bˆhm of Chulitnacula complicates its family-level placement. (1895) included in his new genus three additional spe- On the other hand, studies by Zardini (1978), Bandel cies, which seem to be far removed from the type spe- (1991) and N¸tzel (1998) have provided evidence on the cies (see also N¸tzel 1998) and their genus-level posi- protoconch type of closely related forms, including Pro- Journal of the Czech Geological Society 46/1ñ2(2001) 217

1 2 3

Fig. 3. Chulitnacula alaskana (Smith, 1927) from Chulitna (1) and Alexander (2ñ3) terranes; 1 ñ side view of latex replica of external mold (UAM 2633) from locality 118 of Blodgettt and Clautice, 2000 (=field locality 97RR149 of Rocky Reifenstuhl), Healy A-6 quadrangle, south-central Alaska (Chulitna terrane); 2ñ3 side views of specimen (UAM 2634) from USGS Mesozoic locality M1912 (= field locality 63Amp259 of L. P. G. Muffler) in limestone beds within the Hound Island Volcanics on Kuiu Island, Port Alexander D-1 quadrangle (Alexander terrane); all views x3. torcula, the type genus of the family Protorculidae. The p. 116). However, this species seems to be very close to presence of many common shell features between Chu- the type species Chulitnacula alaskana. The Iranian litnacula and the protorculids, such as similar size, gen- Moerkeia jenningsi (Douglas, 1929) differs from Chulit- eral shell shape and ornamentation, strongly suggest nacula alaskana in having a wider sinus and a less no- placement of Chulitnacula in the family Protorculidae. dose keel in adult whorls (N¸tzel ñ Senowbari-Daryan, This taxonomic position is also supported by the pres- 1999, Pl. 4, Fig. 8). In addition, the almost identical shape ence of spiral ornament on the shell base, considered by of the younger whorls of the teleoconch of Moerkeia jen- N¸tzel ñ Senowbari-Daryan (1999) to represent a typi- ningsi (N¸tzel ñ Senowbari-Daryan, 1999, Pl. 4, Fig. 6) cal protorculid shell feature. and Chulitnacula alaskana strongly argues for its place- Included species: Gastropod species previously ment in the genus Chulitnacula. placed in genus Protorcula are known from many areas (Italy, Iran, Indonesia, Alaska) and are in need of a new Chulitnacula alaskana (Smith, 1927) comb. nov. revision. The new genus Chulitnacula is based on one of them and probably unites several previously described 1927 Protorcula alaskana Smith, p. 109, Pl. 103, Figs 9ñ10. gastropod species, earlier assigned to the genus Protor- cula. The whorl shape of Chulitnacula is far removed Description: Medium-sized, high-spired, slender from the type species of Protorcula, Protorcula subpunc- protorculid shell; restored height of largest specimen tata (M¸nster, 1841), and both genera may easily be dis- minimally about 4.0 cm; whorls slightly wider than high; tinguished from one another. Unfortunately, it is difficult whorl profile distinctly angulated by prominent keel sit- to make a complete list of species possibly belonging to uated low on whorl (about one-fourth of whorl height Chulitnacula on the basis of their illustrations, because above lower suture); keel bears nodes, numbering from in many cases they are of poor quality. Nevertheless, Pro- 15 to18 per adult whorl; upper whorl surface above keel torcula bassetti Smith, 1927 from Late Triassic strata on distinctly concave; sutures shallow, but distinct; anoth- Gravina Island, southeastern Alaska, Protorcula parvu- er, much lower keel situated just on boundary between la Krumbeck, 1913, from Indonesia, and Promathilda (?) lateral and basal sides of whorl; latter keel rounded and jenningsi Douglas, 1929, from Iran most probably belong lacks nodes; whorls join at this keel; shell base conical, to Chulitnacula. The latter species was recently trans- containing an angle about 45∞ with shell axis; growth ferred to genus Moerkeia Bˆhm, 1895 by N¸tzel and lines form distinct wide, U-shaped arch (sinus) between Senowbari-Daryan (1999), who noted that ìthis species lateral keel and upper suture, culminating about one- differs in some respects from the type species of the ge- fourth of whorl height below upper suture; growth lines nus Moerkeiaî (N¸tzel ñ Senowbari-Daryan, 1999, opisthocline below sinus, crossing keel to lower suture, 218 Journal of the Czech Geological Society 46/1ñ2(2001) and continuing onto shell base; ornament consists of nu- dinates for this locality is the SW¼ of the NE¼ of the merous, fine spiral threads which cover lateral and basal NW¼ of Section 19, T10N, R42W of the Taylor Moun- whorl sides; shell structure and protoconch unknown. tains D-3 1:63,360-scale quadrangle. These specimens Occurrence: The type material of Chulitnacula alas- were recovered from a band of silicified fossils at the east kana (Smith 1927) is from the Chulitna terrane of south- end of a prominent rubble crop exposure visible from the central Alaska and was collected on July 15, 1917, by air composed of yellow-orange weathering, platy silty lime S. R. Capps of the U. S. Geological Survey, who was mudstone. The fauna from this locality was briefly listed leading a USGS geological field mapping party in the in Blodgett et al. (2000) and the bivalves and gastropod upper Chulitna region. The locality cited by Smith is molluscs from the locality are described by McRoberts ñ USGS Mesozoic locality 10093, which is noted as ìCo- Blodgett (in press). Molluscs dominate the fauna from this peland Creek at Camp July 14î (Smith 1927, p. 109). locality and include approximately 11 species of gastro- This locality which consists of stream gravels along Co- pods. Chulitnacula alaskana is represented here by nine peland Creek is situated in the Healy A-6 1:63,360-scale specimens that represent the largest sized gastropod spe- quadrangle. Further information on this locality can be cies in the collection. The teleoconch of this species close- found in Martin (1926, p. 44) who cites this locality as ly compares with the Chulitna terrane material in general being a ìstream bar of Copeland Creek.î Subsequently, shape, however, the coarsely silicified character of the Smith (1927) in his monograph on Upper Triassic fau- Farewell terrane material did not allow for preservation of nas of western North America named the species Protor- the finer spiral elements of ornamention. cula alaskana based on material collected by Capps at Chulitnacula alaskana (Smith) also is present in the USGS Mesozoic locality 10093, and indicated this spe- Alexander terrane of southeastern Alaska. It has been ob- cies to be of probable Carnian age. Two specimens were served by us (Figs 3.2, 3.3) at a single locality collected illustrated by Smith (1927, Pl. 103, Figs 9, 10), with the by N. J. Silberling and L. P. J. Muffer in 1963 (USGS holotype being designated as the specimen illustrated in Mesozoic locality M1912; = field locality 63Amp259 of figure 9. During the 1997ñ1998 field mapping effort of L. P. G. Muffler of the U. S. Geological Survey) from the Alaska Division of Geological & Geophysical Sur- limestone beds within the Hound Island Volcanics on veys in the Healy A-6 1:63,360-scale quadrangle of Kuiu Island in the Port Alexander D-1 1:63,360-scale south-central Alaska, new material of this species was quadrangle. This locality is shown as locality 29 on geo- discovered at three localities (localities 118, 120, and 151 logic map of Muffler (1967, Pl. 1, locality 29). Accord- of Blodgett ñ Clautice 2000). Specimens from locality ing to Muffler (1967, p. C43), this locality is situated on 151 (collected in 1997 by Marti Miller of the U. S. Geo- a cove 2 miles north of the west end of Kadak Bay on logical Survey, her field number 97AM241) are conspe- Kuiu Island and is of late Norian age. Additional infor- cific with Chulitnacula alaskana and several of these are mation on the locality is provided by the USGS locality illustrated here (Fig. 2). This locality is located on the register which gives the following ìNorth shore of tidal slightly flattened part of the ridge just below the break inlet directly west of triangulation station ìLuckî from in slope that occurs between the 5000 and 5100 foot con- limestone overly Triassic volcanics. 17,750 feet S7∞E tour lines in the SW¼ of the SW¼ of the SE¼ of Sec- from triangulation station ìLow.î tion 2, T22S, R13W of the Healy A-6 1:63,360-scale quadrangle. This locality according to Miller (written Acknowledgments. We are grateful to the Committee for commun. 1997) is in the lowermost beds of the JTrs unit Exploration and Research of the National Geographic of Jones et al. (1980). Several tens of meters stratigraph- Society for financial support in our study of Upper Tri- ically below this locality is the transistional contact with assic gastropod faunas and their paleobiogeography from the underlying Trrb unit of Jones et al. (1980). The mor- western North America. Karen Clautice of the Alaska Di- phological type of the hydrozoan Heterastridium present vision of Geological & Geophysical Surveys, Fairbanks, in the transistional zone between these two units indicates Alaska was helpful in collaborative field studies of the a late Norian age for this interval (George Stanley, per- Chulitna district during 1997 and 1998. We thank Nor- sonal communicatio). One specimen from locality 118 man Silberling, Lakewood, Colorado, for providing us (collected in 1997 of Rocky Reifenstuhl of the Alaska Di- with his most useful database for USGS Triassic fossil vision of Geological & Geophysical Surveys, his field collections. Casey McKinney, USGS, Denver, Colorado, number 97RR149) is illustrated here (Figs 3-1). This lo- also provided invaluable help with access to the USGS cality is from the JTrs unit and is situated slightly above Triassic fossil collections in the Denver USGS storage the center of the SW¼ of Section 8, T21S, R12W of the facility. We have also benefited from useful discussion Healy A-6 1:63,360 scale quadrangle. concerning Triassic global stratigraphy with George D. Chulitnacula alaskana (Smith) also has been found in Stanley, Jr., University of Montana, Missoula, and E. Tim a Norian age limestone unit in the Nixon Fork subterrane Tozer, formerly of the Geological Survey of Canada (now of the Farewell terrane of southwestern Alaska. These retired), Vancouver, Canada. Our deep felt appreciation specimens were recovered from a single locality, sampled is also expressed to A. J. Boucot for his helpful review by Blodgett during two separate years: his locality 84RB32 of this paper. (which is the same as his 99RB35). The geographic coor- Submitted September 26, 2000 Journal of the Czech Geological Society 46/1ñ2(2001) 219

References Erwin, D. H. (1994): Gastropods, p. 27ñ30. In: Stanley, G. D. ñ Gonz·lez- LÈon, C. ñ Sandy, M. R. ñ Senowbari-Daryan, B. ñ Doyle, P. ñ Bandel, K. (1991): ‹ber triassische ìLoxonematoideaî und ihre Bezie- Tamura, M. ñ Erwin, D. H. (1994): Upper Triassic invertebrates from hungen zu rezenten und pal‰ozoischen Schnecken. ñ Pal‰ontologis- the Antimonio Formation, Sonora, Mexico. Journal of Paleontol- ches Zeitschrift, 65, 3/4:239ñ268. ogy, Memoir 36, v. 68, supplement to No. 4: 33 p. Batten, R. L. (1985): Permian gastropods from Perak, Malaysia. Part 3. Fr˝da, J. ñ Rohr, D. M. (1999): Taxonomy and paleobiogeography of the The murchisoniids, cerithiids, loxonematids and subulitids. ñ Ameri- Ordovician Clisospiridae and Onychochilidae (Mollusca). ñ Acta can Museum Novitates, 2829, 34p. Universitatis Carolinae ñ Geologica, 43(1/2): 405ñ408. Blodgett, R. B. (1992): Taxonomy and paleobiogeographic affinities of Gehrels, G. E. ñ Berg, H. C. (1994): Chapter 13. Geology of southeastern an early Middle Devonian (Eifelian) gastropod faunule from the Liv- Alaska, p. 451-467. In: Plafker, G. ñ Berg, H. C., eds., The Geology engood quadrangle, east-central Alaska. ñ Palaeontographica Abtei- of Alaska. The Geology of North America (DNAG), Volume G-1. lung A, 221:125ñ168. Grant-Mackie, J. A. ñ Silberling, N. J. (1990): New data on the Upper ñ (1998): Emsian (Late Early Devonian) fossils indicate a Siberian Triassic bivalve Monotis in North America, and the new subgenus origin for the Farewell terrane. Short Notes on Alaskan Geology 1997. Pacimonotis. ñ Journal of Paleontology, 64:240ñ254. ñ Alaska Division of Geological and Geophysical Surveys Profes- Gray, J. E. (1853): On the divisions of ctenobranchous gasteropodous sional Report 118:27ñ34. Mollusca into larger groups and families. ñ The Annals and Maga- Blodgett, R. B. ñ Boucot, A. J. (1999): Late Early Devonian (late Emsian) zine of Natural History, including Zoology, Botany, 2, 11:124-133. eospiriferinid brachiopods from Shellabarger Pass, Talkeetna C-6 Haeussler, P. J. ñ Coe, R. S. ñ Onstott, T. C. (1992): Paleomagnetism of quadrangle, south-central Alaska and their biogeographic importance; the Late Triassic Hound Island Volcanics: revisited. ñ Journal of Geo- further evidence for a Siberian origin of the Farewell and allied Alas- physical Research, 97, B13:19,617ñ19,639. kan accreted terranes. ñ Senckenbergiana lethaea, 72(1):209ñ221. Hillhouse, J. W. (1977): Paleomagnetism of the Triassic Nikolai Green- Blodgett, R. B. ñ Brease, P. F. (1997): Emsian (late Early Devonian) bra- stone, McCarthy Quadrangle, Alaska. ñ Canadian Journal of Earth chiopods from Shellabarger Pass, Talkeetna C-6 quadrangle, Denali Sciences, 14, 11:2578ñ2592. National Park, Alaska indicate Siberian origin for Farewell terrane. Hillhouse, J. W. ñ GrommÈ, C. S. (1980): Paleomagnetism of the Triassic ñ Geological Society of America, Abstracts with Programs, 29(5),5. Hound Island Volcanics, Alexander Terrane, southeastern Alaska. ñ Blodgett, R. B. ñ Clautice, K. H. (2000): Fossil locality map for the Healy Journal of Geophysical Research, 85:2594ñ2602. A-6 Quadrangle, south-central Alaska. ñ Alaska Division of Geolog- ñ (1984): Northward displacement and accretion of Wrangellia: New ical & Geophysical Surveys Report of Investigations 2000-5: 42 p. paleomagnetic evidence from Alaska. ñ Journal of Geophysical Re- Blodgett, R. B. ñ Fr˝da, J. (1999): New Devonian gastropod genera im- search, 89:4461ñ4477. portant for paleogeographic reconstructions. ñ Journal of the Czech Jones, D.L. ñ Cox, A. ñ Coney, P. ñ Beck, M. (1982): The growth of Geological Society, 44(3-4):293ñ308. western North America. ñ Scientific American, 247, 5:70ñ84. Blodgett, R. B. ñ Fr˝da, J. ñ Racheboeuf, P. R. (1999): Upper Middle Jones, D. L. ñ Silberling, N. J. ñ Csejtey, B., Jr. ñ Nelson, W. H. ñ Blome, Devonian (Givetian) gastropods from the Kersadiou Formation, Brit- C. D. (1980): Age and structural signficicance of ophiolite and ad- tany, France. ñ Journal of Paleontology, 73:1081ñ1100. joining rocks in the Upper Chulitna district, south-central Alaska. ñ Blodgett, R. B. ñ Fr˝da, J. ñ Stanley, G. D., Jr. (2001): Delphinulopsidae, U. S. Geological Survey Professional Paper 1121-A, 21 p. a new neritopsoidean gastropod family from the Upper Triassic (Car- Jones, D. L. ñ Silberling, N. J. ñ Coney, P. J. ñ Plafker, G. (1987): nian) of the Wallowa terrane, northeastern Oregon. ñ Journal of the Lithotectonic terrane map of Alaska (west of the 141st Meridan). ñ Czech Geological Society, 46:(3/4):221ñ231. U. S. Geological Survey Map MF-1874-A, 1 sheet, scale 1:2,500,000. Blodgett, R. B. ñ Rohr, D. M. ñ Boucot, A. J. (1988): Lower Devonian Kittl, E. (1894): Die Gastropoden der Schichten von St. Cassian der gastropod biogeography of the Western Hemisphere. In: McMillan, s¸dalpinen Trias. III. Theil. ñ Annalen des Kaiserlich-Kˆniglichen N. J.ñ Embry, A. F.ñ Glass, D. J. (eds.), Devonian of the World: Naturhistorischen Hofmuseums 9:143-277. Wien. anadian Society of Petroleum Geologists Memoir 14, 3:285ñ305. Knight, J. B. (1930): The gastropods of the St. Louis, Missouri, Pennsylva- ñ (1990): Early and Middle Devonian gastropod biogeography. In: nian outlier: The Pseudozygopleurinae. ñ Journal of Paleontology, McKerrow, W. S. ñ Scotese, C. R. (eds.), Palaeozoic Paleogeography 4:Supplement 1, 88 p. and Biogeography, Geological Society (London) Memoir 12:277ñ284. Knight, J. B. ñ Cox, R. L. ñ Keen, A. N. ñ Batten, R. L. ñ Yochelson, E. L. Blodgett, R. B. ñ Wilson, F. H. ñ Stanley, G. D., Jr. ñ McRoberts, C. A. ñ ñ Robertson, R. (1960): Systematic descriptions, p. I169ñI324. In: Sandy, M. R. (2000): Upper Triassic stratigraphy and fauna of the R. C. Moore (ed.), Treatise on Invertebrate Paleontology, Part I, Taylor Mountains D-2 and D-3 quadrangles (SW part of the Fare- Mollusca 1. Geological Society of America and University of Kan- well terrane), southwest Alaska. ñ Geological Society of America sas Press, Lawrence. Abstracts with Programs, 32(6):A-4. Koken, E. (1892): Ueber die Gastropoden der rothen Schlernschichten Bˆhm, J. (1895): Die Gastropoden des Marmolatakalkes. ñ Palaeon- nebst Bermerkungen ¸ber Verbreitung und Herkunft einiger riassi- tographica, 42:211ñ308. cher Gattungen. ñ Neues Jahrbuch f¸r Mineralogie, Geologie und Coney, P. J. ñ Jones, D. L. ñ Monger, J. W. H. (1980): Cordilleran suspect Palaeontologie 2/1:25ñ36. terranes. ñ Nature, 288:329ñ333. Krumbeck, L. (1913): Obere Trias von Buru und MisÛl. ñ Palaeon- Conti, M. A. ñ Fischer, J. C. (1982): La fauna a gastropods du Jurassique tographica Supplement 4, Abteilung 2:1-162; Stuttgart. moyen de Case Canepine (Umbria, Italie). ñ Systematique, paleo- McRoberts, C. A. ñ Blodgett, R. B. (in press): Upper Triassic (Norian) biogeographie, paleoecologie. Geologica Romana 21:25ñ183. molluscs from the Taylor Mountains quadrangle, southwest Alaska. ñ Cossmann, M. (1909): Essais de palÈoconchologie comparÈe. Volume 8, U. S. Geological Survey Professional Paper. 348 p., Paris. Martin, G. C. (1926): The Mesozoic stratigraphy of Alaska. ñ U. S. Geo- Cox, L. R. (1960): Thoughts on the classification of the Gastropoda. ñ logical Survey Bulletin 776:493 pp. Proceedings of the Malacological Society of London, 33:239ñ261. Montanaro Gallitelli, E. ñ Russo, A. ñ Ferrari, P. (1979): Upper Triassic Decker, J. ñ Bergman, S. C. ñ Blodgett, R. B. ñ Box, S. E. ñ Bundtzen, T. coelenterates of western North America. ñ Bolletino della Societa K. ñ Clough, J. G. ñ Coonrad, W. L. ñ Gilbert, W. ñ Miller, M. L. ñ Paleontologica Italiana, 18:133ñ156. Murphy, J. M. ñ Robinson, M. S. ñ Wallace, W. K. (1994): Chapter 9. Muffler, L. P. J. (1967): Stratigraphy of the Keku Islets and neighboring Geology of southwestern Alaska, p. 285-310. In: Plafker, G. ñ Berg, parts of Kuiu and Kupreanof Islands, southeastern Alaska. ñ U. S. H. C., eds., The Geology of Alaska. The Geology of North America Geological Survey Bulletin 1241-C: 52 p. (DNAG), Volume G-1. M¸nster, G. G. zu. (1841): Beschreibung und Abbildung der in den Douglas, J. A. (1929): A marine Triassic fauna from Eastern Persia. ñ Kalkmergelschichten von St. Cassian gefundenen Versteinerungen, p. Quarterly Journal of the Geological Society of London, 85:624ñ648. 25-152. In: Wissmann ñ M¸nster, Beitr‰ge zur Geognosie und 220 Journal of the Czech Geological Society 46/1ñ2(2001)

Petrefacten-Kunde des s¸dˆstlichen Tirolís vorz¸glich der Schichten Silberling, N. A. (1985): Biogeographic significance of the Upper Trias- von St. Cassian. In: G. G. zu M¸nster, Beitr‰ge zur Petrefacten-Kunde, sic bivalve Monotis in Circum-Pacific accreted terranes, p. 63ñ70. Heft 4. Bayreuth, Buchner. In: Howell, D. G., ed., Tectonostratigraphic terranes of the Circum- Newton, C. R. (1983): Paleozoogeographic affinities of Norian bivalves Pacific region. Circum-Pacific Council for Energy and Mineral Re- from the Wrangellian, Peninsular, and Alexander terranes, western sources Earth Science Series, Number 1. North America, p. 37ñ48. In: Stevens, C. H., ed., Pre-Jurassic rocks Silberling, N. A. ñ Grant-Mackie, J. A. ñ Nichols, K. M. (1997): The Late in Western North America Suspect Terranes. ñ Pacific Section, Soci- Triassic bivalve Monotis in accreted terranes of Alaska. ñ U. S. Geo- ety of Economic Paleontologists and Mineralogists, Los Angeles, logical Survey Bulletin 2151: 21 p. 141 p. Smith, J. P. (1927): Upper Triassic marine invertebrate faunas of North Nichols, K. M. ñ Silberling, N. J. (1979): Early Triassic (Smithian) am- America. ñ U. S. Geological Survey Professional Paper 141: 262 p. monites of paleoequatorial affinity from the Chulitna terrane, Stanley, G. D., Jr. (1979): Paleoecology, structure, and distribution of southcentral Alaska. ñ U. S. Geological Survey Professional Paper Triassic coral buildups in western North America. ñ University of 1121-B: 5 p. Kansas Paleontological Contributions, Article 65: 58 pp. Nokleberg, W. J. ñ Moll-Stalcup, E. J. ñ Miller, T. P. ñ Brew, D. A. ñ Stone, D. B. (1982): Triassic paleomagnetic data and paleolatitudes for Grantz, A. ñ Reed, J. C., Jr. ñ Plafker, G. ñ Moore, T. E. ñ Silva, Wrangellia, Alaska, in Short Notes on Alaska Geology, 1981. ñ Alaska S. R. ñ Patton, W. W., Jr. with contributions on specific regions by Division of Geological & Geophysical Surveys Geologic Report Blodgett, R. B. ñ Box, S. E. ñ Bradley, D. C. ñ Bundtzen, T. K. ñ 73:55-62. Dusel-Bacon, C. ñ Gamble, B. M. ñ Howell, D. G. ñ Foster, H. L. ñ Wenz, W. (1938): Gastropoda.Teil 1, Lieferung 2: Allgemeiner Teil und Karl, S. M. ñ Miller, M. L. ñ Nelson, S. W. (1994): Prosobranchia, p. 241ñ480. In: O. H. Schindewolf (ed.), Handbuch Tectonostratigraphic terrane and overlap assemblage map of Alaska. der Pal‰ozoologie, Band 6, Gebr¸der Borntraeger, Berlin. ñ U. S. Geological Survey Open-file Report 94ñ194, 53 p., 1 sheet, Zapfe, H. (1962): Beitr‰ge zur Pal‰ontologie der nordalpinen Riffe. Ein scale 1:2,500,000. Massenvorkommen von Gastropoden im Dachsteinkalk des Tennen- N¸tzel, A. (1998): ‹ber die Stammesgeschichte der Ptenoglossa (Gas- gebirges, Salzburg. ñ Annalen des Naturhistorischen Museums Wien, tropoda). Berliner Geowissenschaftliche Abhandlungen, Reihe E, 65:57ñ69. Band 26: 229 pp. ñ (1965): Beit‰ge zur Pal‰ontologie der nordalpinen Riffe. Die Fauna N¸tzel, A. ñ Senowbari-Daryan, B. (1999): Gastropods from the Late der ìerratischen Blˆckeî auf der Falmbergalm bei Gosau, Oberˆster- Triassic (Norian-Rhaetian) Nayband Formation of central Iran. ñ reich (Brachiopoda, Scaphopoda, Gastropoda, Cephalopoda). ñ Ann. Beringeria, 23:93ñ132; Wurzburg. Naturhist. Mus. Wien, 68:279ñ308. Panuska, B. C. ñ Stone, B. C. (1985): Latitudinal motion of the Wrangel- Zardini, R. (1978): Fossili Cassiani (Trias medio-superiore). Atlanti dei lia and Alexander terranes and the Southern Alaska superterrane, p. Gasteropodi della Formazione di S. Cassiano Raccolti Nella Regione 109ñ120. In: Howell, D. G., ed., Tectonostratigraphic terranes of the Dolomitica Attorno a Cortina díAmpezzo. ñ Edizioni Ghedina Cor- Circum-Pacific region. Circum-Pacific Council for Energy and Min- tina, Cortina díAmpezzo, 58 p. eral Resources Earth Science Series, Number 1. ñ (1985): Fossili Cassiani (Trias medio-superiore). Primo aggi- Plafker, G., ñ Berg, H. C. (1994): Chapter 33. Overview of the geology ornameto allí Atlante dei Bivalvi e secondo aggiornamento and tectonic evolution of Alaska, p. 989ñ1021. In: Plafker, G. ñ Berg, allíGasteropodi della formazione di S. Cassiano raccolti nella H. C. eds., The Geology of Alaska. The Geology of North America regione Dolomitica attorno a Cortina díAmpezzo. ñ Cortina (DNAG), Volume G-1. díAmpezzo, 17 p.