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Middle Ordovician (Llandeilan) radiolarians from. West Junggar, Xinjiang, China. Solomon Buckman* and Jonathan C. Aitchison. Department of Earth Sciences, ...
Middle Ordovician (Llandeilan) radiolarians from West Junggar, Xinjiang, China Solomon Buckman* and Jonathan C. Aitchison Department of Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong SAR, China

ABSTRACT: A distinctive long-spined Inaniguttid dominated radiolarian fauna is present in cherts of the Kekesayi terrane in west Junggar, Xinjiang Province, China. This fauna contains moderately well preserved specimens of Protoceratoikiscum clarksoni on which the presence of caveal ribs and patagial tissue can be observed. Characteristics of the fauna are similar to others of correlative late Middle Ordovician (Llandeilan) age known from Scotland (U.K.) suggesting that Protoceratoikiscum clarksoni may be biostratigraphically useful.

INTRODUCTION Studies of early protozoan evolution suggest a lack of mineralized skeletons until the Cambrian (Lipps 1993) with the first appearance of radiolarians expected at sometime in the Early Cambrian. However, descriptions of verifiably Cambrian faunas containing unambiguous radiolarian forms remain rare. Although occurrences of undoubted radiolarian faunas of low diversity are known from the Cambrian (Dong et al. 1997; Won and Below 1999) they are of low diversity. Abundant and diverse, well-preserved, recognizably radiolarian material is extremely rare below the Ordovician. Ordovician radiolarians are also not well known and have only been reported from a few localities worldwide. Early studies of ~ r d o v i c i a n material include reports of radiolarians from Spitsbergen (Fortey and Holdsworth 1972), New York State (Ruedemann and Wilson 1936) and the former USSR, in particular Kazahkstan (Nazarov 1971, 1975, 1977; Nazarov and Popov 1976, 1980; Nazarov et al. 1975) and Estonia (Nazarov and Nylvak 1983). Many of these faunas were not well illustrated and remain somewhat enigmatic. Further studies of new localities together with improvements in SEM technology and techniques for the extraction of radiolarian tests from their surrounding matrix have lead to a gradual increase in our knowledge of Ordovician radiolarian faunas. Upper Ordovician faunas have been reported from Nevada (Dunham and Murphy 1976; Renz 1990b), Newfoundland (Renz 1990a); Australia (Webby and Blom 1986) and the Baltic (Gorka 1994). Middle Ordovician radiolarians have been reported from China (Li 1995; Wang 1993), Scotland (Danelian 1999; Danelian and Clarkson 1998; Danelian and Floyd, 2001) and Australia (Goto et al. 1992; Iwata et al. 1995; Umeda et al. 1992). Lower Ordovician radiolarians have recently been reported from Scotland (Aitchison 1998), the Bay of Islands ophiolite complex in Newfoundland (Aitchison et al. 1998) and Nevada (Kozur et al. 1996).

*Current address: School of Geoscience, Minerals and Civil Engineering, University of South Australia, Mawson Lakes Campus, Mawson Lakes, South Australia 5095, Australia

No long Ordovician stratigraphic intervals over which well-preserved radiolarians have been recovered are known. Thus Ordovician radiolarian biostratigraphy relies on isolated occurrences from widely separated localities. Nevertheless faunas of particular ages are consistently similar at widely separated localities and a distinct biostratigraphic succession appears to be present. Broad changes in the nature of radiolarians through Early Paleozoic time were described by Holdsworth (1977) and Nazarov and Ormiston (1986). A biozonation was first elaborated for Ordovician radiolarians by Nazarov and Ormiston (1993) and recently this has been refined in somewhat more detail (Aitchison and Noble 1997; Noble and Aitchison 2000). By developing a biostratigraphy it is hoped that it will prove to be useful to geologists working in orogenic collages similar to those of Mesozoic and late Paleozoic age where radiolarian biostratigraphy has been so successfully applied. In this paper a Middle Ordovician radiolarian fauna from a similar sort of orogenic collage is discussed. Regional Geological Setting

Northwest China constitutes part of the Eurasian Paleo-Asiatic Orogenic Belt or Altaids (Sengor et al. 1993). This belt is a major tectonic feature extending for more than 2000km from the Ural Mountains of Russia and Kazakhstan through the Chinese Tianshan and Junggar mountain ranges to Mongolia and NE China. It separates the Siberian Craton to the north from the Tarim-Northern China-Korean Craton to the south and records the history of the Paleo-Asiatic Ocean. This region has begun to attract numerous studies worldwide, because of its importance to understanding of the tectonics and continental growth of Eurasia. Until now only preliminary reconstructions have been made of the outlines of the Paleo-Asiatic Ocean, its history, its dimensions, and the initial position, and affinities of the smaller continental blocks. In the West Junggar area of NW China several sutures and ophiolite belts mark the traces of Paleozoic collision zones. The exact age and significance of many sutures is still debated. Adetailed understanding of the tectonic evolution of this area cannot be achieved until the relative ages of constituent rocks is established. Ophiolites are key markers of collision tectonics and radiolarian biostratigraphy should greatly aid in studies of their relative ages and significance.

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Solomon Buckman and Jonathan C. Aitchison: Middle Ordovician (Uandeilan) radiolariansfrom West Junggar; Xinjiang, China

TEXT-FIGURE 1 Geological map of the West Junggar region, Xinjiang Province, China. The Kekesayi terrane comprises a small portion of the larger Ebinur terrane shown on the map. The studied section lies to the NNW of Tangbale (45'07.870'N 083'21.815'E).

radiolarians present. We have undertaken collection of new samples of radiolarian cherts from these localities and herein we present details of the oldest of the faunas we have extracted.

The ophiolites which are scattered across the West Junggar region occur in a series of discontinuous belts. Previous studies (Feng et al. 1989) document several ophiolitic zones grouped by their location, age of associated sediments and style of deformation into four belts. From SW to NE these are Tangbale, Mayila, Dalabute and Barleik/Honggulelung/Hebukesair. Rocks contained within individual ophiolite zones include: Tangbale zone (Upper Cambrian-Ordovician) which has mostly serpentinized peridotite (largest body 12.4km2), ophiolitic melange with blocks of peridotite, gabbro, pillow lava, minor dyke swarms, cherts, tuffs, glaucophane schists and amphibolite; Mayila zone (Middle-Upper Silurian) which has ophiolitic slices tectonically interleaved with lower Paleozoic volcaniclastic rocks, turbidites, cherts and lavas. Serpentinite melange with blocks of basalt, gabbro, pyroxenite, tuff, chert and siltstone; Dalabute (Darbut) zone (Upper Devonian-Lower Carboniferous) in which there is ophiolitic melange with peridotite, gabbro, pillow lavas, basaltic breccias, cherts, other pelagic sediments and fossiliferous limestone; and BarleiW Honggulelung/ Hebukesair zone (Ordovician) where peridotite, massive gabbro, and pillow basalt are distributed over a 10km2 area.

The Tangbale terrane includes rocks of ophiolitic affinity, including large peridotite bodies of harzburgitic composition and cumulate gabbros. The upper diabase dyke and pillow basalt sections of a typical ophiolite are not present at Tangbale. Sphene from small plagiogranite screens within the gabbros has been isotopically dated at 523.7 k 7.2 Ma using Pbffb isotope methods (Feng et al. 1989). A serpentinite-matrix melange is commonly found around the margins of peridotite bodies and extends into adjacent faults. The highly depleted harzburgitic rocks are typical of supra-subduction zone ophiolites (Buckman 2000).

Radiolarians have previously been reported from Tangbale (Ordovician: Wang 1982), Mayila (Silurian: Li 1994) and Dalabute (Devonian: Feng et al. 1989). The radiolarians are of different ages in each area. As most previous work pre-dates the establishment of a reliable Early Paleozoic radiolarian biozonation there is some conflict in existing reports as to the ages of the

The Kekesayi terrane includes oceanic pillow lavas overlain by hyaloclastic breccia, red radiolarian chert, fine-grained green tuffs and minor volcaniclastic sediments. Kekesayi basalts are tholeiitic and have characteristics typical of MORB (Feng et al. 1989; Zhang et al. 1993; Zhu et al. 1983). Most of the preserved blocks that make up the Kekesayi terrane are completely

Local Geology

Tangbale district is host to the oldest rocks in West Junggar. It consists of three separate terranes, the Tangbale, Kekesayi and Laba terranes, that were amalgamated together in the Early Paleozoic and built upon by an island-arc to form a fourth composite terrane - the Ebinur terrane (Buckman 2000).

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Green siliceous tuff Red radiolarian chert Basaltic hyaloclastite Serpentinite-matrix melang

as-

TEXT-FIGURE 2 A well-preserved fragment of the Kekesayi terrane. This sequence is found on the northern margin of the Tangbale peridotite body (4S007.870'N 083°21.815'E)within a serpentinite-matrix melange. It consists of basal basaltic hyaloclastite overlain by red ribbon-bedded radiolarian cherts (12m thick) and green siliceous radiolarian tuffs and minor clastic sediments. Small goat for scale.

fault-bounded and enveloped by schistose serpentinite. The best-preserved fragments of this terrane are found within serpentinite melange on the northern side of the Tangbale ultramafic body (text-fig. 2). In general they strike east-west and dip steeply to the north along thrust planes. The average thickness of the chert horizon in the Kekesayi terrane is only about 12m. However, fragments of the same chert horizon can be found within a zone several kilometers across-strike indicating that there has been extensive structural repetition of the stratigraphy. The composition of rocks and style of structural repetition within this terrane is reminiscent of that observed in subduction complexes.

marks the beginning of the formation of the composite Ebinur terrane. The andesites of the Suyuenka Complex were previously thought to represent the upper levels of the Tangbale ophiolite but the petrography and geochemistry of these volcanics indicates they are clearly derived from calc-alkaline magmas generated by island-arc activity. Volcaniclastic sediments of the Qiargayi Formation unconformably overlie the Suyuenka Complex. These formed as a series of turbidites sourced from underlying terranes and the actively forming volcanic Suyuenka Complex. Fine-grained siltstones within this formation contain graptolite fossils that constrain the age of formation to the Early Silurian.

The Laba terrane consists of metamorphic rocks in fault contact with surrounding units. It is interpreted as a suite of sedimentary and volcanic rocks that were underplated in a subduction complex and subject to widespread amphibolite facies metamorphism. In rare cases the metamorphism attained the high pressures associated with blueschist facies as seen in glaucophane-lawsonite schist blocks within the serpentinite-matrix melange (Zhang 1997).

Previous Work

The Suyuenka Complex consists of calc-alkaline basaltic to andesitic rocks that intrude, and were erupted on top of the Tangbale, Kekesayi and Laba terranes. Development of these rocks indicates that terrane amalgamation had occurred and

Radiolarians have previously been reported in chert samples from the Kekesayi terrane by Wang (1982), who recorded Middle to Late Ordovician radiolarian assemblages but did not list or figure the species present. Feng et al., (1989) suggested that on further examination these radiolarians might be considered to be Middle to Late Devonian. Apparently the Devonian age corresponds to ages obtained from gastropods extracted from limestone knockers within the serpentinitemelange, but the ongin of these knockers is uncertain. Radiolarian cherts and siltstones from the nearby Mayila ophiolitic melange were processed with some success by Li

Solomon Buckman and Jonathan C. Aitchison: Midde Ordovician(Llandeilan)radiolariansfrom WestJunggal;Xinjiang, China

Thickness (m)

RockType thrust fault

20

-m .

19 .

Samples

l8-

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-

green tuff and elastic material

In this study we collected approximately 50 radiolarian chert samples from the Tangbale district (45 07.733"N 083 21.974" E) and processed them using standard hydrofluoric extraction techniques. About 40% of samples yielded radiolarian tests. The best-preserved material was collected from two basalt-chert-tuff blocks found lying within serpentinite-matrix melangeon the northern margin of the Tangbaleperidotite body, on the eastern side of the Tangbale River. Individual blocks are approximately 20m thick by 50m long (text-fig. 2). Although these units are highly disrupted and laterally discontinuous, there is a surprising lack of internal deformation. Samples were taken over 1-2m stratigraphic intervals, as shown in text-figure 3, from two separate blocks located approximately 100m apart. In total there are about 12m of red radiolarian chert and 4m of green, radiolarian tuff. Sample TA118 yielded the best preserved material. The upper sections of the Kekesayi terrane are dominated by coarser-grained tuffs and minor volcaniclastic lenses. Only the lowermost 4m of this green siliceous tuff contains significant quantities of radiolarians and above this level the green sedimentsare slightly coarser-grained.Presumably an influx of arc-derived tuffaceous sediments at this stage diluted the contribution of radiolarians to the total sediment input. Faunal details

1

-

0 -

red hematitic basaltic hyaloclastite, containing pillow basalt fragments thrust fault

TEXT-FIGURE3 Stratigraphic section through cherts of the Kekesayi terrane at 4S007.870'N083O21.81S'E, West Junggar, Xinjiang, China.

(1991, 1994).He suggested a Middle Wenlockian age for these cherts based on the presence of well preserved radiolarians including: Ceratoikiscum leonides Renz, Ceratoikiscum sp. A, Ceratoikiscum sp. B, Haplentactinia sp., Haplentactiniid gen. et sp. indet., Haplentactinia?pentochela Li, Haploelus dipolus Li, Haplopolus sp. A, Haplopolus macracantha (Rust), Inanihella aff. macracantha (Rust), Inanihella sp., Inaniguttid gen. et sp. indet., Onnistonia pteracaena Li, Palaeoephippium pariramosum Goodbody, P. radices Goodbody, Palaeoscenidium jlammatum Goodbody, Palaeoscenidium sp., Palaeotripus cancellatus Goodbody, P. septemistellatus Li 1994, Secuicollacta nesymmetra Li , Secuicollacta? sp., and Spongentactinella? sp.

As with many Early Paleozoic faunas, from the Middle Ordovician - Late Silurian Inaniguttids are common and comprise the main component of acid residues from the Tangbale samples. Inaniguttids belong to long-spined morphotype I (Noble and Aitchison 2000) and possess multiple-latticed cortical shells with few (-8lhemisphere) long non-tapering rodded spines. Unfortunately as preservation in these cherty faunas is commonly poor the outermost cortical shells are often missing or only fragmentally preserved. Their former presence can be detected in the form of small fragments (not spinules) located near the bases of spines. The most significant feature of the Tangbale fauna is the appearance of 'triangular' taxa in the form of the arachnoidal genus ProtoceratoikiscumGoto et al. This genuswhich is known from Australia (Goto et al. 1992), China (Li 1995) and Scotland (Danelian and Clarkson 1998; Danelian 1999; Danelian and Floyd, 2001). The conodont genus Periodon occurs in samples from both China and Scotland and is indicative of a Middle Ordovician (Llandeilan) age. Unfigured conodonts ascribed to Plectodina were reported by Goto et a1 (1992) from their Australian fauna allowing assignment to the Middle to Upper Ordovician which is consistent with ages assigned to other faunas. Protoceratoikiscum may have given rise to Ceratoikiscum Deflandre by the Early Silurian. The first known appearance of true Ceratoikiscum Deflandre is in the late Llandoverian, and radiation occurred throughout the Silurian and Devonian. We note that specimens of Protoceratoikiscum clarksoni Danelian in our faunas are possibly slightly better preserved than others reported from elsewhere. On some of our specimenswe believe that we can detect the presence of caved ribs and patagial tissue, both of which are typical of Ceratoikiscum. The Tangbale fauna is typical of radiolarian faunas ascribed to 'long-spined Inaniguttid zone 1' of Noble and Aitchison (2000).

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We do not see any pylomate sphaerellarians that might indicate a slightly younger age transitional with 'pylomate/large concentric sphaerellarian zone 1' (Noble and Aitchison 2000). Neither do we see taxa characteristic of older faunas known from the Lower Ordovician. For this reason and because of co-occurring conodont faunas we consider that our fauna is most probably of late Middle Ordovician (Llandeilan) age. SYSTEMATIC PALEONTOLOGY Class ACTINOPODA Calkins 1909 Subclass RADIOLARIA Miiller 1858 Superorder POLYCYSTIDA Ehrenberg 1838; emend. Riedel 1967 Order SPUMELLARIA Ehrenberg 1875 Family INANIGUTTIDAE Nazarov and Ormiston 1984 Inaniguttid gen et sp. indet Plate 2A-T Description: Numerous inaniguttids are present in the Tangbale fauna. Unfortunately their preservation is typical of material in chert samples from elsewhere and is imperfect. We figure the specimens in order to provide future researchers with an indication of the nature of the total fauna present in our samples. We note the presence of spinose apophyses on some specimens located a few tens of microns from the outermost preserved shell. These are most likely the only remnants of once delicate outer shells that are commonly present on inaniguttids from faunas where preservation is much better. The state of preservation of our specimens is such that no generic assignment can be made with confidence. Order ALBAILLELLARIA Deflandre 1953; emend. Holdsworth 1969 Family CERATOIKISCIDAE Holdsworth 1969 Genus Protoceratoikiscum Goto, Umeda and Ishiga 1992 Type species: Protoceratoikiscum chinocryostallus Goto, Umeda and Ishiga 1992 ProtoceratoikiscurnGoto, Umeda and Ishiga 1992, p. 165 Original description (from Goto, Umeda and Ishiga 1992): Seven rod like spines are radiating from the central part of the shell in horizontal plane, and two of these curve distally with clockwise rotation. In this attitude, spines being numbered from first to seventh, two spines (first or top and fourth or bottom spines) are nearly straight and sitting opposite site, and form intersector or main spine. Third and seventh spines extending both sides of main spines, distally curved. Second spine is sitting on right side and fifth and sixth spines sitting on left side. By spines connect these spines and form 'spider web' like shell. Remarks: Small triangle-like opening in the central portion is constructed by three paired spines and indicates a close relationship to the basic structure of Ceratoikiscum. Protoceratoikiscurn clarksoni Danelian emend. herein Plate 1, figures A-T Protoceratoikiscumsp. cf. F! sirnilistellaturnDANELIAN and CLARKSON 1998, p. 135, fig. 2j. Protoceratoikiscum sp. DANELIAN and CLARKSON 1998, p. 135, fig. 2k, 21. Protoceratoikiscurn sp. cf.P chinocryostallus DANELIAN and CLARKSON 1998, p. 135, fig. 2i. Protoceratoikiscurn clarksoni Danelian. - DANELIAN and FLOYD 2001, p. fig. 5a-e.

Description: From Danelian and Floyd (2001). Skeleton made up of seven (7) straight rod-like primary spines situated horizontally and distributed radially along a circle formed by three rows of arches (or straight by-spines) joining the primary spines. The latter taper gently distally, but also rapidly proximally towards the center, inwards of the innermost circle. The median row is in general circular-oval and follows closely the shape of the innermost row, although parts of it are slightly offset in some specimens. First and fourth primary spines positioned on opposite sides of a practically straight line, while the angle formed between the first and seventh primary spines is smaller (20"-33") than the angles formed between other spines. A characteristic triangular structure is thus formed on most specimens, made of the two primary spines (first and seventh) and straight by-spines, which are often offset with respect to the adjacent archeshy-spines. Secondary spines may be present and positioned radially on the median row, but do not extend inwards to the center of the skeleton. Emended diagnosis:As described in Danelian and Floyd (2001). This species also possesses pataigal tissue in the vicinity of spine 5 and caveal ribs adorn arches near spine 1. Remarks: Our specimens of Protoceratoikiscum clarksoni Danelian are commonly fragmentary and rarely well preserved. Nevertheless they are clearly similar to the specimens described in Danelian and Floyd (2001). Their specimens are also poorly preserved and possibly less abundant than those in our samples. By examining the combined features of numerous fragmentary specimens we are able to comment further about this taxon. All specimens on our plate 1 have been oriented in the same manner with the spine numbered (1) in Danelian and Floyd (2001) located at a 3 o'clock position and other spines numbered sequentially in an anticlockwise direction. We note that a distinct development of spongy tissue can be observed on some specimens (Plate 1 figs. A, D, H, and K). A similar zone of spongy tissue is present on a specimen figured in Danelian and Floyd (2001 Fig 5e). We interpret this to be the equivalent of the patagial tissue present o n other ceratoikiscids. -we further note the presence on one specimen (Plate 1 fig. D) of small caveal ribs developed on the middle row of arches around the vicinity of spine 1. Figure C of Plate 1 depicts caveal ribs inferred to have been broken from a specimen of this taxon. Arches are developed or preserved to varying degrees on our specimens and in some instances the zone between arches appears to be fused or infilled. On some specimens auxilary spines are also developed. Danelian and Floyd (2001) regarded Protoceratoikiscum arachnoides Goto, Umeda and Ishiga as a junior synonym of Protoceratoikiscum chinocrystallum Goto, Umeda and Ishiga. However we prefer to continue to regard these two taxa as different species. As noted by Danelian and Floyd (2001) spines on Protoceratoikiscum similistellatum Li 1995 appear to continue right across the innermost circle of arches whereas those on Protoceratoikiscum clarksoni Danelian taper towards the center and simply appear to touch one another. Occurrence: Kekesayi terrane, West Junggar, Xinjiang Province, NW China. 45 07.733" N Lat. 083 21.974" E Long. Type Locality: Southern Uplands, southern Scotland. Worldwide range and occurrence: Protoceratoikiscum clarksoni Danelian is known from the Southern Uplands, southern Scotland and from the Tangbale district, west Junggar, NW China (this study). Middle Ordovician so far as is known.

Solomon Buckman and Jonathan C. Aitchison: Middle Ordovician (Llandeilan)radiolariansfrom West Junggal; Xinjiang, China

ACKNOWLEDGMENTS We thank Naizkhan "King of the Goats" for providing accommodations at the bucolic pueblo of Tangbale. Funding for this research was provided by the Hong Kong Research Grants Council (Project No. HKU 70891978). Lui Jiangbing and He Wenjun assisted with fieldwork. John Talent and Ruth Mawson are thanked for their assistance with conodontology.

FENG, Y., COLEMAN, R. G., TILTON, G. and XIAO, X., 1989. Tectonic evolution of the West Junggar region, Xinjiang, China. Tectonics, 8: 729-752 FORTEY, R. A., and HOLDSWORTH, B. K., 1970. The oldest known well-preserved Radiolaria. Bollettino della Societa Paleontologica Italiana, 10, 35-41.

REFERENCES

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AITCHISON, J. C., 1998. A Lower Ordovician (Arenigian) radiolarian fauna from the Ballantrae Complex, Scotland. Scottish Journal of Geology, 34: 73-81.

GOTO, H., UMEDA, M. and ISHIGA, H., 1992. Late Ordovician radiolarians from the Lachlan Fold Belt, southeastern Australia. Memoirs of the Faculty of Science, Shimane University, 26: 145-170.

AITCHISON, J. C., FLOOD, P. G. and MALPAS, J., 1998. Lowermost Ordovician (basal Tremadoc) radiolarians from the Little Port Complex, western Newfoundland. Geological Magazine, 135: 413-419.

HOLDSWORTH, B. K., 1969. Namurian Radiolaria of the genus Ceratoikiscum from Staffordshire and Derbyshire, England. Micropaleontology, 15: 221-229.

AITCHISON, J. C., and NOBLE, P. J., 1997. 1997. Early Paleozoic radiolarian biostratigraphy. INTERRAD VIII, Bierville, France abstracts p. 7.

, 1977. Paleozoic Radiolaria: Stratigraphic distribution in Atlantic Borderlands, in Swain, F.M., ed., Stratigraphic Micropaleontology of Atlantic Basin and Borderlands, Volume 6: Developments in Paleontology and Stratigraphy: Amsterdam, The Netherlands, Elsevier, p. 167-184.

BUCKMAN, S., 2000. Tectonics and Mineralization of West Junggar, northwest China, unpublished PhD thesis, University of Hong Kong, Hong Kong. 301 pp. DANIELAN, T., 1999. Taxonomic study of Ordovician (LlanvirnCaradoc) Radiolaria from the Southern Uplands (Scotland, U.K.), Geodiversitas, 21: 625-635. DANIELAN, T., and CLARKSON, E. N. K., 1998. Ordovician radiolaria from bedded cherts of the Southern Uplands. Scottish Journal of Geology, 34: 133-137. DANIELAN, T., and FLOYD, J. D., 2001. Progress in describing Ordovician biodiversity from the Southern Uplands (Scotland, UK). Transactions of the Royal Society of Edinburgh: Earth Sciences, 91: 489-498.

IWATA, K., SCHMIDT, B. L., LEITCH, E. C., ALLAN, A. D. and WATANABE, T., 1995. Ordovician microfossils from the Ballast Formation (Giralambone Group) of New South Wales. Australian Journal of Earth Sciences. 42: 371-376. KOZUR, H. W., MOSTLER, H., and REPETSKI, J. E., 1996. Well preserved Tremadocian primitive Radiolaria from the Windfall Formation of the Antelope Range, Eureka County, Nevada, U.S.A: Geologisch - Palaontologische Mitteilungen Innsbruck, 21 : 245-27 1. LI, H. S., 1991. First discovery of Middle Silurian Radiolaria fossils in Xinjiang. Scientia Geologica Sinica (Ti Chih K'o HsuehDizhi Kexue), 1: 75. , 1994. Middle Silurian radiolarians from Keerhada, Xinjiang. Acta Micropalaeontologica Sinica, 11: 259-272.

DEFLANDRE, G., 1953. Radiolaries fossils. In: GrassC, P. P., Ed. Traite de Zoologique. 1 pt. 2: 389-436, Paris, Masson et Cie. DONG X., KNOLL, A. H. and LIPPS, J. H., 1997. Late Cambrian Radiolaria from Hunan, China. Journal of Paleontology, 71: 753-758. DUNHAM, J. B. and MURPHY, M. A., 1976. An occurrence of well preserved Radiolaria from the Upper Ordovician (Caradocian), Eureka County, Nevada. Journal of Paleontology, 50: 882-887. EHRENBERG C. G,, 1875. Fortsetzung der mikrogeologischen Studien als Gesammt-Uebersichtder mikroskopischen Palaontologie gleichartig analysirter Gebirgsarten der Erde, mit specieller Rucksicht auf den Polycystinen-Mergel von Barbados. Konigliche Akademie der Wissenschaften zu Berlin, Abhandlungen, Jahre 1875: 1-225.

, 1995. New genera and species of middle Ordovician Nassellaria and Albaillellaria from Bai-jingsi, Qilian Mountains, China. Scientia Geological Sinica, 4: 331-346. LIPPS, J. H., 1993. Fossil Prokaryotes and Protists: Oxford/London, UK, Blackwell Scientific Publications, 342 p. NAZAROV, B. B., 197 1. Ordovikskie radiolyarii Tsentraln'ogo Kazakhstana v Sbornik: Tezizy dokladov (Ordovician Radiolaria of Central Kazakhstan in collection of thesis reports), Vtoroe stratigraficheskoe soveschanie po dopaleozoyu i paleozoyu Kazakhstana (The second stratigraphic meeting on the pre-Paleozoic and Paleozoic of Kazakhstan), Alma-Ata, USSR, pp. 97-98. 1975. Radiolaria of the Lower-Middle Paleozoic of Kazakhstan. Academiia Nauk SSSR, Geologicheskii Institut, 275:l-202.

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PLATE 1 All specimens illustrated are from sample TA118 collected from mid Ordovician cherts of the Kekesayi terrane (45'07.870'N 083"21.815'E), West Junggar, Xinjiang, China. All scale bars = 100pm. AC,ErO, Protoceratoikiscum clarksoni Danelian emend. QS herein

D,%T Protoceratoikiscum ?clarksoni

Solomon Buckman and Jonathan C. Aitchison

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Solorrlon Buckman* and Jonathan C. Aitchlson: Middle Ordovician (Llandeilan)radiolariansfrom West Junggar, Xinjiang, China

, 1977. Novoe Semeystvo radiolyariy iz ordovika Kazakhstana (A new radiolarian family from the Ordovician of Kazakhstan). Paleontologicheskii zhurnal (Paleontological Journal)(2): 35-41. NAZAROV, B. B., and NYLVAK, J., 1983. Radiolyarii iz verkhnego ordovika Estonii (Radiolarians from the Upper Ordovician of Estonia). Izvestiya Akademiya Nauk Estonskoy SSR (Bulletin of the Estonian Academy of Sciences), Geologiya (Geology), 32: 1-8. NAZAROV, B. B., AND ORMISTON, A. R., 1984. Vozmozhnaya sistema Radiolyarii Paleozoya (Tentative system of Paleozoic Radiolaria). In: Petrushevskaya M. G. and Stepanjants, S. D., Eds., Morfologiya, ekologiya i evolutsiya Radiolyarii. Materialy IV simpoziuma evropeiskikh radiolyaristov EURORAD IV (Morphology, ecology and evolution of radiolarians. Material from the IV symposium of European radiolarists EURORAD IV). Academiya Nauk SSSR, Zoological Institute, Leningrad, USSR, 64-87. , 1986. Trends in the development of Paleozoic Radiolaria: Marine Micropaleontology, l l : 3-32.

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Manuscript received March 3, 2000 Manuscript accepted July 2, 2001

PLATE 2 A-S: Inaniguttids gen. et sp. indet. from sample TA118 collected from mid Ordovician cherts of the Kekesayi terrane (45007.8701N083O21.815'E), West Junggar, Xinjiang, China. All scale bars = 100pm.

Solomon Buckman and Jonathan C.Aitchison

micropaleontology, vol. 47, no. 4,2001

Plate 2

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