permian fusulinids from the koryak terrane

Journal of Foraminiferal Research, v. 26, no. 3, p. 213-243, July 1996

PERMIAN FUSULINIDS FROM THE KORYAK TERRANE, NORTHEASTERN RUSSIA, AND THEIR PALEOBIOGEOGRAPHIC AFFINITY VLADIMIR!. DAVYDOV

All-Russia Geological Research Institute (VSEGEI), St. Petersburg, Russia 199026 PAUL BELASKY

Department of Geology, San Jose State University, San Jose, CA 95192 USA NELLI !. KARA VA YEV A

Portovaja 1 1/2-41, Magadan, Russia, 685024

diolarian chert, argillite, and Upper Paleozoic limestone of probable atoll origin (Rusakov and Egiazarov, 1958; Egiazarov and Miklukho-Maclay, 1963; Rusakov and Trukhalev, 1964; Alexandrov and others, 1975; Peyve, 1984; Sokolov, 1990). Carboniferous-Lower Permian fossiliferous limestones are well exposed in the western part of the Ekonay terrane (Fig. 2), along the Khatyrka River and its tributary Chetkinvaam (Rusakov and Egiazarov, 1958). Upper Permian limestones are best exposed in the eastern part of the area, along the Nakipeylak, Vaamoch· ka, and Khayidin Rivers and near Pekulneyskoye Lake (Epshtein and others, 1985). Limestones generally occur in fault-bounded blocks (olistostromes) up to several kilometers in lateral exposure and 60 m in thickness. These rocks contain abundant fusulinids, including the verbeek· inids, and rare waagenophyllid rugose corals, as well as crinoids and brachiopods (Rusakov and Egiazarov, 1958; Terekhova and others, 1979; Kachanov, 1984). Only a portion of the fusulinid fauna has been previously described (Epshtein and others, 1985). The occurrence of verbeekinid fusulinids and waagenophyllid rugose corals thousands of kilometers from the Teth· yan realm and in close proximity to Permian faunas with Boreal brachiopods has led to suggestions that the Ekonay terrane, like the Cache Creek and several other terranes in western North America (Fig. 3), is an exotic terrane which originated in the tropical Paleopacific Ocean and was subsequently displaced northward (Sokolov, 1990; Belasky and Runnegar, 1993 ). The Ekonay terrane and Kodiak Island (Stevens, written communication, 1994) represent the north· ernmost and most biogeographically anomalous occurrences of Permian fusulinids of Tethyan affinity (Fig. 1). Thus, systematic studies of the fusulinid faunas from these terranes should not only yield taxonomic and biostratigraphic information but also provide constraints on the original locations of the Ekonay and Cache Creek terranes and place them in the wider context of paleogeography of the Pacific region (Stavsky and others, 1988; Belasky and Runnegar, 1993; Belasky, 1994). The purpose of the present study is to provide a systematic description of the existing collections of fusulinids from the Koryak region (Ekonay terrane) and to compare this fauna with other well-known fusulinid faunas from the circum-Pacific region. The bulk of the material was collected by a number geoscientists in a period of

ABSTRACT

Tethyan fusulinid faunas from 12 localities within the Ekonay complex of the Koryak region (northeastern Russia) represent five stadial assemblages: Asselian, Yakhtashian (Artinskian), Bolorian (Kungurian), Kubergandinian (Roadian), and Midian (upper WordianCapitanian). The fusulinid fauna is diverse (30 genera and more than 65 species) and includes the following new species: Rauserella rusakovi, Acervoschwagerina maclayi, Cha/aroschwagerina kalmykovae. Members of the Verbeekinidae are numerous. Smaller foraminifera inclnde Abadehella koryakensis, n. sp. The Koryak fauna shows affinity to the nearest coeval faunas from the northwestern Pacific region and may have originated in general proximity to them in the western part of the tropical Paleopacific Ocean. According to probabilistic analysis of faunal similarity, the Upper Permian (Midian) fnsulinid fauna of the Koryak region is significantly similar to that of the Kitakami Mountains (northern Japan) and exhibits a moderately high level of similarity to those of the Ussuri and Sikhote-Aiin regions of southeastern Russia and northeastern China. There is no statistically significant similarity between the Koryak terrane and the Cordilleran exotic terranes such as the Cache Creek. INTRODUCTION Koryakia is a large, structurally-complex terrane located north of the Kamchatka Peninsula, along the Pacific coast of northeastern Russia (Fig. 1). It consists of several smaller terranes of varying age and lithology (Fujita and Newbury, 1983; Zonenshain and others, 1987; Sokolov, 1990). The Ekonay terrane (Fig. 2) is particularly enigmatic because its geological and faunal characteristics contrast sharply with those of the surrounding areas (Stavsky and others, 1988; Sokolov, 1990). It is located in the northeastern part of Koryakia, in an area bordered by the Opukha River and Pek· ulneyskoye Lake (62SN; 176'E). The region has been mapped by several groups of Russian geologists since the 1950's (e.g., Rusakov and Egiazarov, 1958; Egiazarov and Titov, 1963), however maps with scale less than 1:500,000 have not been published. The Ekonay complex consists of Carboniferous to Triassic melange containing blocks of spilitic lavas, tuff, ra-

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Asia

North America

FIGURE 1. Index map of present-day circum-Pacific area showing the location of the Koryak terrane (shaded) and other anomalous occurrences of Tethyan biota in western North America (diagonal hachures) and their idealized direction of movement (modified from Yancey, 1979). The square denotes the northeastern part of the Koryak: terrane (Ekonay complex) where most Permian fusulinids were collected.

several decades and includes the undescribed portion of Karavayeva's collection (previously described in part by Epshtein and others, 1985), and the extensive MiklukhoMaclay's collection, given by the St. Petersburg State University to the senior author. The latter collection includes Miklukho-Maclay's random thin sections as well as newly-cut oriented fusulinid thin sections of his specimens. Geographic information on fossil localities is available only for Karavayeva's collection (Appendix 1) because, by the time the present project was initiated, a substantial portion of the thin sections and the accompanying geographic and stratigraphic documentation was missing or destroyed. However, despite the lack of adequate documentation, Miklukho-Maclay's material provides a substantial amount of information on fusulinid taxonomy, Permian biostratigraphy, and paleobiogeographic affinity of the Koryak region and needs to be brought to light. This material represents an additional piece of the puzzle for reconstructing the Late Paleozoic stratigraphy and paleogeography of the Pacific region, and its value is further enhanced by the fact that few, if any, paleontological field investigations are likely to take place in this remote, poorly known, and fascinating region in the near future. Taxonomic descriptions are provided for all new taxa, stratigraphically important (i.e., age-diagnostic) species from Koryakia, and species that are variable or insufficiently well known. Only a general discussion is provided for taxa, whose representatives in Koryakia do not differ significantly from the type specimens. All taxa reported from the Koryak region are listed on Table 1. The collection described in this study is presently housed at the All-Russia Geological Research Institute (VSEGEI) in St. Petersburg and the Department of Geology, San Jose State University, San Jose, CA. Type specimens and . the illustrated material are stored at the Chernyshev Central Geological Museum (CGM) in St. Petersburg, Russia.

FIGURE 2. Northeastern part of the Koryak region showing the generalized area of exposure of the Ekonay complex (shaded) and the drainage pattern. Numbers represent waterways along which Permian fusulinids were collected: 1-0pukha River; 2-Chetkinvayam River; 3- Yomrautvayam River; 4-Khatyrka River; 5- Elginmyvayam River; 6-Nak:ipeylak: River; 7- Bezymannaya River; 8-Bystraya River; 9-Khayidin River; 10-Peschannaya River; 11-Vaamochka River; 12-Pekulneyskoye Lake.

200km

c:J Eastern KLAMATH

lo-t

FUSULlNID ASSEMBLAGES The five Permian fusulinid assemblages recognized from the study area were age-dated (Fig. 4) using Leven's (1980)

.F IGURE 3. Location of principal Cordilleran terranes bearing Permian fusulinid faunas.

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PERMIAN FUSUliNIDS FROM THE KORYAK REGION TABLE 1.

A chart plotting occurrences of fusulinid species in the Koryak region against the locality/sample numbers. Sample: age:

E.~timated

Pseudoreiche/ina cf darvasim Pseudoreiche/ina aff s/(weniis. A very large, uniformly expanding shell, whose shape remains relatively constant in all volutions. Septa are very strongly fluted. Description. Shell elongate, fusiform, ranges from 19.20 mm to 25.60 mm in length (L), 4.6--6.00 mm in diameter (D). The form ralio (LID) is 3.00-4.60 mm, and the diameter of proloculus is 0.150-0.188 mm. The coiling is uniform, slightly more loose after the third volution. Keriotheca is thick (0.11 0--0.130 mm). Septa are thin, very intensely fluted. The fluting is regular in the inner volutions. where septal folds are nearly square. The fluting becomes irregular to chaotic after the fourth volution, and in axial sections transforms into a fine cancellate meshwork. Phrenothecae are present near the tunnel in the outer volutions. Axial filling is present in the inner two volutions. Hook-shaped pseudochomata are present in the first four volutions. The tunnel is long and narrow. Discussion. The specimens from Koryak region generally resemble the type species of Acervoschwagerina (A. endoi) bur differ from it in their larger size, more uniform coiling, and more intense septal fluting in all volutions. Age. Yakhtashian. Material studied. Twelve specimens from two localities (750, 997). Etymology. Named in honor of the eminent Russian micropaleontologist, A. D. Miklukho-Maclay. Genus Skinnerella Coogan, 1960 Skinnerella cuniculata (Igo), 1967 Pl. 5, Figs. 1, 2 Parafusulina cuniculata: Igo, 1967, pl. I, figs. 1-3. Description. Shell inflated, fusiform, uniformly expanding. Length (L) and diameter (D) are 8.30-8.70 mm and 3.60-3.80 mm, respectively. The form ratio gradually increases from 1.81 for the first volution to about 2.4 for the last volution. The proloculus is large, 0.300.42 mm in diameter. Keriotheca is thick (0.09-0.15 mm). Septa are relatively thick, fluted. The fluting is intense and regular and in axial sections septa form high-, subquadratic and closely spaced folds, which are thickened in the upper part. Axial deposits are present in the first, second. and third volutions. The tunnel is low and narrow. Discussion. The specimens from Koryakia are very similar to typical S. cuniculata and differ only in having a more inflated shell, somewhat more intense and regular fluting of septa, and no phrenothecae. Age. Kubergandinian (Roadian). Material studied. Six specimens from locality 9-22. Skinnerella aff. crassa (Deprat), 1913 Pl. 5, Figs. 3. 4 Fusulina crassa: Deprat, 1913, pl. VI, figs. 1-5. Description. An inflated, fusiform shell, ovoid in the inner volutions. Axial poles are elongated and sharply rounded. Proloculus is. very

PLATE 4 1, 2, 4, 6 Acervoschwagerina maclayi Davydov, n. sp. 1 Axial section of holotype, locality 997-4, sample CGM 12502/61 X10; 2 the same, X5; 4 subaxial section of paratype, locality 997-5, sample CGM 12502/62 X5; 6 axial section of paratype, locality 750-2, sample CGM 12502/64 X5. 3, 5, 7 Acervoschwagerina endoi Hanzawa. 3 Axia: section, locality 750-8, sample CGM 12502/65 X 10; 5 axial section, locality 997-2, sample CGM 12502/63 X5; 7 axial section, locality 997-1, sample CGM 12502/66 XlO.

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large, 0.40--0.46 mm in diameter. The coiling is moderately tight and uniform. Keriotheca is 0.05-0.08 mm thick. Septa are thin, intensely and regularly fluted. Axial tilling is pronounced in the inner four volutions. The tunnel is low, very narrow in the inner volutions, gradually widening in the outer volutions. Discussion. The specimens from the Koryak region differ from typical S. aff. crassa in having a very large proloculus and a relatively loose, uniform coiling in the inner volutions. This discrepancy in the character of the early ontogenetic stage suggests that the described specimens may represent a new species. However, more material is needed in order to resolve this problem. Age. Kubergandinian. Material studied. Four specimens from locality 9-22.

Skinnerella schucherti (Dunbar and Skinner), 1937 Pl. 5, Figs. 5, 6; Pl. 6, Figs. 1. 3 Parafu:mlina schucherti: Dunbar and Skinner, 1937, pl. 64, fig. I 1. Description. A fusiform shell with pointed axial poles in the outer volutions. The shell is more inflated in the inner volutions (1-4) and has more rounded axial poles. The coiling is moderately tight and uniform. The diameter of proloculus is 0.28-0.40 mm. The keriotheca is thick (0.09-0.12 mm). The septa are thin and intensely and regularly fluted. The fluting becomes more irregular near the axial ends and less intense near the tunnel. Axial filling is present in the inner two volutions. The tunnel is low and narrow. Discussion. The specimens from Koryakia are identified as 5. schucherti on the basis of the shape of the shell in all volutions, the coiling pattern, and the character of the axial poles. However, they differ from typical S. schucherti in having poorly developed axial filling and slightly less intense and more irregular fluting of the septa. Typical representatives of S. schucherti are characterized by regular and intense septal fluting and the presence of phrenothecae; the septal folds in axial sections are uniform and trapezoid in shape. The septal folds in axial sections of the specimens from Koryakia are closely spaced and vary in shape from trapezoid to rounded; phrenothecae are absent. Although the described specimens are superficially similar to S. cuniculata (lgo). they can be distinguished from the latter by having a more elongate shell, more intensely folded septa, and axial filling. Age. Kubergandinian. Material srudied. Eight specimens from locality 9-22. Skinnerella nabeyamensis (Morikawa and Takaoka) 1961 Pl. 5, Fig 7 Parafusulina nnbeyamensis: Morikawa and Takaoka, 1961, pl. 8, figs. 1-9.

Description. An inflated (ovoid) shell of 7 volutions with rounded axial poles. The coiling is uniform. The diameter of proloculus is 0.350 mm. The keriotheca is thin (0.075 mm). The septa are also thin and strongly and regularly fluted in all volutions. The septal folds in axial sections are closely spaced and subquadratic in shape. The septal fluting is regular and intense. Axial filling is present in the inner volutions but is not pronounced. The tunnel is low and narrow. Discussion. The shape of the :->hell, the coiling pattern, and the character of septal fluting in the specimens from Koryakia are similar to those of typical S. nabe)•amensis. However, the Koryak specimens differ from the latter in their less intense septal fluting and weaker development of the axial filling. Furthermore, they are distinguished from S. parakinosakii (Morikawa and Isomi) by their larger size, more inflated and uniformly coiled shell, less regular and more intense fluting of septa, and virtual absence of axial filling.

A~

KARAVAYEVA

Age. Midian. Material studied. One specimen from locality 236. Skinnerella cf. multiseptata (Schellwien), 1898 Pl. 5, Fig. 8 Fusulina multiseptata: Schellwien, 1898, pl. XVIII, figs. 2a. Parafusulinn multiseptata: Leven, 1967, pl. XVII, fig. 5; pl. XVIII, fig. I.

Description. An elongate-fusiform shell with pointed axial poles. The first volmion is ovoid in shape. The coiling is uniform and moderately tight. The length (L), diameter of the shell (D), and diameter of the proloculus are 10.2 mm, 3.4 mm, and 0.250 mm, respectively. The form ratio gradually increases from 1.81 (first volution) to 3.00 (last volution). The keriotheca is thick (0.09-0.12 mm). Septa are thin and strongly fluted. Septal fluting is regular in the inner volutions, irregular and even chaotic in the outer volutions, particularly near the axial poles, and weak near the tunnel. The tunnel is initially narrow but gradually widens in the outer volutions. Axial filling is weakly developed in first few volutions. Discussion. Specimens from the Koryak region are identified as S. cf. multiseptata on the basis of the general shape of the shell, the coiling pattern, and the character of septal fluting. However, they differ from typical S. multiseptata in their slightly more inflated shell, less regular and less intense septal fluting and weaker development of the axial filling. The described specimens can be distinguished from S. ambigua (Deprat) by an almost complete absence of axial filling, more intense septal fluting, and more sharply pointed axial poles. Age. Kubergandinian. Material studied. One specimen from locality 9-22. Skinnerella po:stkraffti (Leven), 1967 Pl. 5, Figs. 9, 10 Parafusulina postkrajfti: Leven, 1967, pl. XV, figs. 4, 5. Description. A subcylindrical shell, slighlly compressed in the middle portion. The inner volutions are elongate-fusiform; the shape of the shell stabilizes after the third or the fourth volution; rather tightly coiled. Axial poles are narrowly rounded. The length and diameter of the shell are 6.70-9.40 mm and 3.00-3.70 mm, respectively. The diameter of proloculus is 0.25--0.28 mm. The keriotheca is thick (0.070.12 mm). Septa are relatively thick (0.05 mm) and strongly but generally irregularly fluted. Septal fluting becomes less pronounced near the tunnel, which is low, moderately wide, and gradually expanding. Axial filling is well developed in all volutions. Discussion. Specimens from the Koryak region are identified as S. cf. postkra.ffti on the basis of the general shape of the shell, the coiling pattern, and the character of septal fluting and axial filling. However, they differ from typical S. postkra.ffti in their tighter coiling and more intense septal fluting. The described specimens can be distinguished from S. kraffti (Schellwien, 1898) by their larger number of volutions, more intense folding of the septa, and the common presence of cuniculi. Age. Bolorian. Material studied. Six specimen:;; from two localities (1000, 1001). Skinnerella khabakovi (Leven), 1967 Pl. 6, Figs. 4, 5 Pseudofusulina khabakovi: Leven, 1967, pl. XI, figs. 3, 4. Description. A compressed-fusiform shell of 6-7 volutions, slightly concave in the middle section. The two inner volutions are ovoid in

PLATE 5 Magnification X 10 1, 2 Skinnerella cuniculata (lgo). 1 Axial section, locality 9-22-20, sample CGM 12502/67; 2 axial section, locality 9-22-8, sample CGM 12502/ 68. 3, 4 Skinnerella aff. cra.ua (Deprat). 3 Axial section, locality 9-22-16, sample CGM 12502/69; 4 axial section, locality 9-22-30, sample 12502/ 70. 5, 6 Skinnerella schucherti (Dunbar and Skinner). 5 Axial section, locality 9-22-15, sample CGM 12502171; 6 axial section, locality 9-22-26, sample CGM 12502172. 7 Skinnerella cf. nabeyamensis (Morikawa and Takaoka). Subaxial section, locality 236-6-1, sample CGM 12502173. 8 Skinnerella cf. multiseptata (Schellwien). Axial section, locality 9-22-18, sample CGM 12502174. 9, 10 Skinnerella postkra.ffti (Leven). Axial section, locality 1001-8, sample CGM 12502175; 10 axial section, locality 1000-4, sample CGM 12502176.

PERMIAN FUSUUNIDS FROM THE KORYAK REGION

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PERMIAN FUSUIJNIDS FROM THE KORYAK REGJON

shape. The length, diameter. and form ratio of the shell are 8.40-9.20 mm, 3.80-3.90 mm, and 2.20-2.36, respectively. Keriotheca is thick (0.09-0.11 mm). Septa are also thick and strongly and somewhat irregularly fluted. The septal fluting becomes less intense near tile tunnel, which is low, narrow, and expands only slightly toward the outer volutions. Axial filling is well-developed in the four inner volutions, absent in the outer volutions. Rare phrenothecae are present io the last volution. Discussion. Specimens from the Koryak region are identified as S. cf. khabakovi on the basis of the general size and shape of the shell, the coiling pattern, and the character of axial filling. Howt;:ver, they differ from typical S. khabakovi in theh more regu\ar and less intense fluting of the septa, tighter coiling in the first few volutions, and more rounded axial poles. In a1