Well-preserved Radiolarians Research Articles

Radiolarian and planktonic foraminiferal biochronology of the Pano Panagia section, Lefkara Formation (Maastrichtian, Upper Cretaceous), Cyprus

Well-preserved radiolarians were studied from a section of the Lefkara Formation near Pano Panagia Village (southwestern Cyprus) which was previously dated as Upper Cretaceous (Maastrichtian). More than 60 radiolarian species were recovered in this section, including Amphipyndax tylotus Foreman, Archaeodictyomitra lamellicostata (Foreman), Lithomelissa (?) sp. aff. L. (?) hoplites Foreman, Lithomespilus coronatus Squinabol sensu Hollis, 1997, Theocapsomma comys group Foreman. Two radiolarian zones were recognized. The Amphipyndax tylotus Radiolarian Zone is traced within the Maastrichtian part of the studied section. The upper limits of stratigraphic ranges of some genera, e.g., Archaeospongoprunum Pessagno, Crucella Pessagno, Multastrum Vishnevskaya, Patellula Kozlova, Praeconocaryomma Pessagno, Pseudoaulophacus Pessagno, Afens Riedel and Sanfilippo, Archaeodictyomitra Pessagno, Foremanina Empson-Morin and Xitus Pessagno are, therefore, expanded to the Maastrichtian. Planktonic foraminifera were identified, represented by an assemblage with Gansserina gansseri (Bolli), Contusotruncana contusa (Cushman) and Pseudotextularia elegans (Rzehak), which indicate stratigraphic interval from Gansserina gansseri to Pseudoguembelina hariaensis Zones (uppermost Campanian to middle part of upper Maastrichtian). Geochemical data indicate a Mid-Maastrichtian Event with relatively high δ13С value in the lower part of the section and a moderate negative trend of δ13С value towards the upper part of the section.

Age and origin of accreted ocean plate stratigraphy in the North Qilian belt, NE Tibet Plateau: evidence from microfossils and geochemistry of cherts and siltstones

The accretionary complex (AC) in the North Qilian belt comprises coherent and chaotic units consisting of bedded cherts, pelagic mudstone, shale, turbidites, basalt, limestone, blueschist, eclogite lenses and ophiolitic mélange. Cherts from the Donggoukou and Biandukou outcrops in the north of the blueschist belt contain abundant Middle Ordovician radiolarians together with rare conodonts. Well-preserved radiolarians also occur in cherts associated with high-pressure/low-temperature rocks in the Baijingsi AC outcrop. Conodonts of Floian–Dapingian age and Middle Ordovician radiolarians also occur in the Shihuigou AC. Geochemical analysis of 23 cherts reveals variable SiO 2 contents (74.56–97.16 wt%) and high mean Al/(Al + Fe + Mn) ratios ranging from 0.35 to 0.85, indicating a non-hydrothermal origin. Ce/Ce* and La N /Yb N ratios of 0.70–1.22 and 0.67–1.59 respectively are high and variable, similar to those of associated muddy siltstone (0.59–0.96 and 1.14–1.55, respectively), suggesting near-trench deposition with associated terrigenous input. Together with the metamorphic ages of blueschists and eclogites, the North Qilian belt AC formed by accretion of ocean plate stratigraphic successions in response to subduction of the Proto-Tethyan Ocean prior to 450 Ma. Supplementary material: Appendices 1-6 are available at: https://doi.org/10.6084/m9.figshare.c.5418275 Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts

First Report of Early Permian Albaillellarian Radiolarians from East Timor

Abstract. Two early Permian radiolarians, Pseudoalbaillella postscalprata Ishiga, 1983 and Pseudoalbaillella sakmarensis ( Kozur, 1981 ), are described from a calcareous nodule of the Permian siliciclastic succession distributed in north-central East Timor. The association probably indicates a Sakmarian (early Cisuralian) age. This is the first report of age-diagnostic Permian radiolarians from East Timor and demonstrates a potential source of well-preserved radiolarians of the Permian siliciclastic succession.

Late Triassic to Early Jurassic radiolarian, conodont and ammonite assemblages from the Tavuscayiri block, Mersin Mélange, southern Turkey: Time constraints for the T/J boundary and sedimentary evolution of the southern margin of the northern Neotethys

The Mersin Mélange (northwest of Mersin city) includes a variety of large sedimentary blocks/tectonic slices of Palaeozoic and Mesozoic origins. Of these, the latter represents facial and tectonostratigraphic counterparts of the Beysehir-Hoyran Nappes (remnants of the northern Neotethys). The Tavuscayiri Block, located at the center of the mélange and close to the Orbuklukeli hill, is one of such Mesozoic occurrences, with a continuous pelagic sequence from the Upper Triassic to Lower Jurassic. At the Orbuklukeli hill, a succession of middle Norian to Toarcian age has been precisely dated, which starts with conodont assemblages for the Norian and Rhaetian and includes radiolarians for the upper Rhaetian. An acidic tuff layer corresponds to the T-J boundary, which passes above to an increasingly dominating chert-bearing limestone series, marking a gradually deepening-upward of the sequence. The early Hettangian radiolarians are poorly represented, but diverse and well-preserved radiolarians have been retrieved from the middle Hettangian to the Pliensbachian. A total of eighty-five taxa, including fourteen new species, have been determined. In addition to these, one new genus (Praeudalia Tekin, n. gen.) has been described from the Rhaetian part of the section. The top of the section is represented by nodular limestones in Ammonitico rosso facies, including a diverse Toarcian ammonite fauna. All lithologies of the Orbuklukeli section along the Tavuscayiri Block can be correlated with the previously described lithologies of the Kayabasi Group/Formation in the Bozkir Unit, and Gülbahar/Gümüslü units in the Lycian Nappes.

Middle Jurassic radiolarians from Jinlang, Zedong, southern Xizang (Tibet), China

Moderately to well-preserved radiolarians have been extracted from nine greyish green and purplish-red bedded cherts in the mud-matrix mélange of the eastern Yarlung-Zangbo Suture Zone (YZSZ) at Jinlang Section, Zedong, southern Xizang (Tibet). Forty-two species belonging to 27 genera, including Middle Jurassic characteristic species such as Laxtorum (?) jurassicum Isozaki and Matsuda, Laxtorum (?) hichisoense Isozaki and Matsuda, Stichocapsa japonica Yao, Stichocapsa robusta Matsuoka, Parahsuum (?) magnum Takemura, Sella chrafatensis (El Kadiri), and Unuma typicus Ichikawa and Yao are recognized and three assemblages, Laxtorum (?) jurassicum Assemblage (Aalenian), Quarticella ovalis Assemblage (late Bajocian), and Stichocapsa robusta Assemblage (middle Bathonian) are established in ascending order. These assemblages can be well correlated to the Middle Jurassic Unitary Association (UA) Zones (Baumgartner et al., 1995) in west Tethys and coeval biozones in Japan and provide reliable age information for the Middle Jurassic stratigraphic correlation of the pelagic sediments along the YZSZ.

Middle Ordovician (Darriwilian) radiolarians from the Crawford Group, Scotland

AbstractA diverse assemblage of moderately well-preserved radiolarians occurs in the Ordovician cherts of the Crawford Group in the Southern Uplands terrane of the Scottish borders. A total of 8 genera and 11 species are described. Taxa present correlate to the Middle Ordovician Pygodus anserinus biozone. Key species identified include: Proventocitum procerulum, Inanigutta gansuensis, Inanigutta sp. cf. I. complanata, Inanibigutta sp. cf. I. verrucula, Inanibigutta sp. cf. I. pinglianensis, ?Inanibigutta inconstans, ?Inanihella penrosei, Haplentactinia armillata, ?Oriundogutta ramificans and Syntagentactinia sp. A new species Haplotaeniatum albaensis is introduced here and described on the basis of details of skeletal architecture observed using microcomputed tomography, demonstrating the potential of this technique as a tool for improving the understanding of radiolarian taxonomy.

Accretion of the Anuy Zone, Tectonic Zonation, and Evolution of the Samarka Accretionary Complex: Details of Evolutionary Scenario of the Sikhote-Alin Segment of the East Asian Continental Margin

The Sikhote-Alin Orogen in the southeast of Russia is a collage of geological terranes of various age and tectonic origin, which formed along the East Asian continental margin as a result of the Jurassic–Early Cretaceous subduction of the Pacific oceanic plates. The Jurassic Samarka accretionary complex (AC) and the Early Cretaceous Zhuravlevka turbidite basin in the southern part of the orogen are considered indicators of subduction continental margin and transform plate boundary regimes, respectively. The regime conversion was assumed at the end of the Jurassic, when subduction stopped. Our biostratigraphic study of radiolarians from siliceous and fine-clastic sedimentary rocks has revealed the latest oceanic deposits and the youngest, Early Cretaceous fragment of the Samarka AC in its less studied northeastern part, which is ascribed to the Anuy tectono-stratigraphic element. The well-preserved radiolarians allow accurate dating of cherts, siliceous mudstone, and mudstone. This and other available biostratigraphic data allow the reinterpretation of the stratigraphy of the accreted oceanic sedimentary rocks. The refined stratigraphy is interpreted as a subsequent change in depositional settings on an oceanic plate, which moves to the convergent plate margin. Cherts accumulated in an oceanic pelagic zone from the Middle Triassic to the Late Jurassic (Early Oxfordian). Siliceous mudstone were deposited in a hemipelagic zone in the early Oxfordian–middle Tithonian. Mudstone and siltstones deposited on an external slope of a deep trench in the late Tithonian–Berriasian. The sandy deposits were deposited in an axial part of the trench in the early Valangian, which best corresponds to the timing of accretion. Thus recognized early Valanginian accretion episode shows that subduction underneath the continental margin lasted longer than previously suggested. The onset of the transform continental boundary regime occurred later, probably, in the late Valanginian. This further details the Mesozoic evolutionary scenario, which was previously proposed for the Sikhote-Alin segment of the East Asian continental margin. We also refine the tectonic zonation and evolution of the Samarka AC.

RADIOLARIAN AGE AND LITHOSTRATIGRAPHY OF LATE CRETACEOUS PELAGIC SEDIMENTS OVERLYING BASALTIC EXTRUSIVE ROCKS, NORTHERN OMAN MOUNTAINS

A detailed radiolarian biostratigraphy of pelagic sediments overlying basaltic extrusive lavas of the Oman Ophiolite is reported for the type locality of the Suhaylah Formation near the Wadi Jizzi River, northern Oman Mountains. The extrusive lavas in the studied section are classified as V1 lava produced by mid-ocean-ridge magmatism. The sedimentary succession in the type section (ca. 18 m thick) is subdivided into three units (in stratigraphic order): metalliferous sediments (Unit 1), red mudstone intercalated with radiolarian chert (Unit 2), and micritic limestone (Unit 3). The recovery of well-preserved radiolarians from all units led to the recognition of three distinctive assemblages: Assemblage A, obtained from metalliferous sediments and chert intercalations within red mudstone, could be correlated with the middle-late Cenomanian fauna; Assemblage B, recovered from red mudstone and chert, is assigned to the early Turonian, based on correlation with radiolarian occurrences across the Cenomanian-Turonian boundary; Assemblage C, recognized in micritic limestone, is broadly identified as Turonian-Coniacian. The age of the Suhaylah Formation has previously been interpreted as early Cenomanian to Coniacian-Santonian; however, the revised age could be from late Cenomanian to Turonian-Coniacian. The estimated possible maximum age of metalliferous sediments (96.5-93.9 Ma) is in good agreement with high-precision U-Pb zircon dates of ophiolite crust attributed to ridge magmatism. The depositional age of the pelagic sediments clearly indicates that the ridge magmatism had ended by ca. 95.5 Ma.

Cretaceous radiolarians from Baliojong ophiolite sequence, Sabah, Malaysia

The Baliojong ophiolite sequence exposed along the Baliojong River in Northern Sabah consists of volcanic rocks, mostly basalts, overlain by sedimentary layers consisting of well-bedded cherts, mudstones and sandstones. The ophiolite sequence occurs as steeply-dipping overturned thrust slices oriented approximately north–south. A total of 42 chert samples were collected from the sedimentary layers. However, most of the samples contain poorly preserved radiolarians. Only nine samples yielded moderately well-preserved radiolarians from three selected thrust slices. A total of 32 taxa were identified. Based on the stratigraphic distribution of selected taxa, the radiolarians can be divided into two assemblage zones. The first assemblage zone is Dictyomitra communis Zone characterized by the occurrence of Dictyomitra communis, Archaeodictyomitra (?) lacrimula, Sethocapsa (?) orca, Dictyomitra pseudoscalaris, and Pantanellium squinaboli. The assemblage indicates Barremian to Aptian in age. The second assemblage zone Pseudodictyomitra pseudomacrocephala Zone contains Pseudodictyomitra pseudomacrocephala, Dictyomitra gracilis, Dictyomitra montesserei, Xitus mclaughlini, and Dictyomitra obesa. This assemblage indicates an age of Albian and the presence of Pseudodictyomitra tiara suggests the age may extend up to Cenomanian. Each thrust slice yielded more or less similar radiolarian assemblages indicating that they all came from the same sedimentary layers.

Late Paleozoic Radiolaria from the Upper Triassic sedimentary mélange in Shangrila, Southwest China and its geological significance

Moderately well-preserved radiolarians were collected recently from the exotic siliceous blocks within the sedimentary mélange of the Upper Triassic Hagong Formation exposed in Shangrila, southwestern China. These radiolarians, characterized by high diversity, include spumellarians, entactinarians, latentifistularians, and albaillellarians. Among them, 28 species of Albaillellaria belonging to 3 genera are taxonomically analyzed. Most species recorded are correlated with coeval radiolarian assemblages from Germany and Japan. Thirteen albaillellarian assemblages are discriminated, ranging in age from Early Carboniferous to Middle Permian. Because the siliceous blocks within the sedimentary mélange originated in the Garze-Litang tectonic belt, the successful recovery of the well-preserved datable albaillellarians provides the age constraints necessary for the interpretation of the tectonic development of the Garze-Litang tectonic belt. On the basis of the deep-water settings indicated by the albaillellarian fauna, we suggest that the sedimentary basin, represented by the Garze-Litang tectonic belt, became a deep-water basin during Early Carboniferous to Middle Permian and, hence, the Dege-Zhongdian microplate must have been gradually separated by rifting from the Yangtze Plate before the Early Carboniferous.

Radiolarians from the Lamar Limestone, Guadalupe Mountains, West Texas

Well-preserved radiolarians are described from a road-cut of the upper Lamar Limestone Member of the Bell Canyon Formation along Highway 62/180 in the Delaware basin of West Texas. The upper part of the Lamar Limestone contains early Capitanian (late Guadalupian) conodonts and fusulinaceans and is assigned to the Reichelina lamarensis and the Jinogondolella postserrata zones, respectively. A total of 31 species were recovered from 17 samples in a ~6m section of micritic laminated limestone. Twenty species are reported from this locality for the first time, including 6 new species; Copiellintra ferula, Copiellintra laurelae, Hegleria agnusiforma, Hegleria globosa, Rectotormentum fengi, and Stigmosphaerostylus wildei. Sectioning and transmitted light microscopy of the spongy taxa reveals internal structures and allows for a more natural grouping of genera and species based on aspects of wall structure, rather than external geometry or presumed internal structure. All of the spongy taxa lack an entactinarian spicule and the genera Copicyntra, Copiellintra, Copicyntroides and Hegleria are reassigned to families within the Spumellaria. Lamar radiolarian assemblages show fluctuations in their faunal composition, alternating between albaillellarian-dominated assemblages composed mostly of Follicucullus spp. and spumellarian-dominated assemblages composed largely of spongy taxa of spherical, oblate, to discoidal shape (Copicyntra, Copiellintra, Copicyntroides, Klaengspongus, Tetrapaurinella, and Hegleria). By far the most common radiolarians are spongy spumellarians and albaillellarians, but latentifistularians also occur sporadically in samples, and entactinarians are rare and occur throughout the section. These marked faunal fluctuations are interpreted to be environmentally driven and is the subject of ongoing investigations using geochemical proxies to reveal paleoecological controls.

Radiolarians from the upper Guadalupian (Middle Permian) Reef Trail Member of the Bell Canyon Formation, West Texas and their biostratigraphic implications

Moderately well-preserved radiolarians are described from two measured sections of the Reef Trail Member of the Bell Canyon Formation (Middle Permian), exposed in the Patterson Hills, Guadalupe Mountains National Park, West Texas. The Reef Trail Member is the youngest member of a series of basinal marine carbonates deposited in the Delaware basin prior to the deposition of the Castile Formation evaporites, and represents the uppermost Guadalupian (upper Capitanian). The Guadalupian-Lopingian boundary is presumed to occur at or just above the top of the Reef Trail-Castile contact because of the presence of C. postbitteri hongshuiensis ~ 2m below the top of the Reef Trail Member in sections in the Patterson Hills. A total of 30 genera containing 51 species were recovered from the Reef Trail Member, belonging to the orders Albaillellaria, Latentifistularia, Spumellaria, and Entactinaria. The following new taxa are described: Raphidociclicus scutum, Camptoalatus volaticus, Pseudoalbaillella delawarensis, Astroentactinia porosa, Stigmosphaerostylus favusa, Polyedroentactinia quadrata, Praedeflandrella firmata, P. prolata, Copicyntra spinosa, Copicyntra irregulata, and Paracopicyntra puncta, and Copicyntroides nazarovi. The following taxa are emended: Raciditor scalae (Caridroit and De Wever 1986), and Klaengspongus Sashida 2000b. Near the top of the Reef Trail Member, there are marked fluctuations in the relative abundances of albaillellarian and latentifistularian species. Fluctuations are possibly controlled by paleoenvironmental changes associated with the onset of the end-Guadalupian extinction event. Biostratigraphically, the fauna most closely correlates with the widely recognized F. bipartitus – F. charveti Zone sensu Caridroit, which we now consider to be uppermost Guadalupian, not Lopingian, and to the Guadalupian F. charveti Zone of Sun and Xia 2006 from oceanic facies in China. Both older and younger biostratigraphic markers also occur in the Reef Trail fauna, including Pseudoalbaillella longtanensis and A. yamakitai, requiring a reevaluation of the reliability of these albaillellarian taxa in biostratigraphy.

Upper Silurian and Devonian pelagic deep-water radiolarian chert from the Khangai–Khentei belt of Central Mongolia: Evidence for Middle Paleozoic subduction–accretion activity in the Central Asian Orogenic Belt

Recent mapping projects undertaken in Central Mongolia have revealed the widespread occurrence of radiolarian chert within a Paleozoic accretionary complex. We present the results of the first detailed tectonostratigraphic and radiolarian biostratigraphic investigations of the Gorkhi Formation in the Khangai–Khentei belt of the Central Asian Orogenic Belt. The Gorkhi Formation consists of sandstone shale, alternating sandstone and shale of turbidite affinity and chert with small amounts of siliceous shale, basalt, limestone, and clast-bearing mudstone. Radiolarian chert that is completely devoid of terrigenous clastic material is commonly associated with underlying basalt (sedimentary contact) and with conformably overlying siliceous shale and turbidite deposits. The tectonic stacking of basalt–chert and chert–turbidite successions is the most remarkable structural feature of the formation. The recovery of moderately well-preserved radiolarians and conodonts from red chert led to the recognition of four radiolarian assemblages that have a combined age range from the latest Silurian (Pridolian) to the Late Devonian (Frasnian). No age control exists for the siliceous shale, shale, and sandstone, although they are considered to be latest Devonian or slightly younger on the basis of stratigraphic relationships with underlying chert. The Gorkhi Formation has previously been interpreted as a thick sedimentary basin deposit overlying an unexposed Archean–Neoproterozoic basement; however, the stratigraphy within individual tectonic slices clearly corresponds to that of an ocean plate stratigraphy of an accretionary complex generated by the trenchward movement of an oceanic plate. From the lowermost to uppermost units, the stratigraphy comprises ocean floor basalt, pelagic deep-water radiolarian chert, hemipelagic siliceous shale, and terrigenous turbidite deposits. The biostratigraphic data obtained in the present study provide corroborating evidence for the existence of an extensive deep-water ocean that enabled the continuous sedimentation of pelagic chert over a period of nearly 50 million years. These data, together with structural data characterized by tectonic repetition of the stratigraphy, indicate that these rocks formed as an accretionary wedge along an active continental margin, possibly that of the Angara Craton. The mid-oceanic chert was probably deposited in the Northern Hemisphere portion of the Paleo–Pacific Ocean that faced the Angara Craton and the North China–Tarim blocks. Thus, we propose that subduction–accretion processes along the Paleo–Pacific rim played an important role in the accretionary growth of the active continental margin of the Angara Craton, directly influencing the evolution of the Central Asian Orogenic Belt.

Permian and Triassic Radiolaria from Northwest Thailand: paleogeographical implications

Well-preserved radiolarians were recovered from seven sections in the Mae Hong Son-Mae Sariang area, northwestern Thailand. 51 species assigned to 34 genera are identified, including 1 new species ( Triassospongosphaera erici Feng sp. nov.) and 19 unidentified species. They are divided into the Late Permian, late Ladinian and middle Carnian radiolarian assemblages. Newly identified radiolarian assemblages, together with the published radiolarian biostratigraphic data from this region, indicate that there was a pelagic basin during the Late Paleozoic and Triassic. This basin was joined to the Chiang Dao and Changning-Menglian oceanic basins, and they represent the main oceanic basin of the Paleotethyan Archipelago Ocean. This main oceanic basin was situated in the traditional “Shan-Thai Block”. Therefore, “the Shan-Thai Block” was not a single block during that stage, but composed of the Paleotethyan Ocean and two continental terranes that were affiliated with the Gondwana and Cathaysian domains, respectively.

Radiolarian faunal turnover across the Oligocene/Miocene boundary in the equatorial Pacific Ocean

The global warming trend of the latest Oligocene was interrupted by several cooling events associated with Antarctic glaciations. These cooling events affected surface water productivity and plankton assemblages. Well-preserved radiolarians were obtained from upper Oligocene to lower Miocene sediments at Ocean Drilling Program (ODP) Leg 199 Sites 1218 and 1219 in the equatorial Pacific, and 110 radiolarian species were identified. Four episodes of significant radiolarian faunal changes were identified: middle late Oligocene (27.5 to 27.3 Ma), latest Oligocene (24.4 Ma), earliest Miocene (23.3 Ma), and middle early Miocene (21.6 Ma). These four episodes approximately coincide with increases and decreases of biogenic silica accumulation rates and increases in δ 18O values coded as “Oi” and “Mi” events. These data indicate that Antarctic glaciations were associated with change of siliceous sedimentation patterns and faunal changes in the equatorial Pacific. Radiolarian fauna was divided into three assemblages based on variations in radiolarian productivity, species richness and the composition of dominant species: a late Oligocene assemblage (27.6 to 24.4 Ma), a transitional assemblage (24.4 to 23.3 Ma) and an early Miocene assemblage (23.3 to 21.2 Ma). The late Oligocene assemblage is characterized by relatively high productivity, low species richness and four dominant species of Tholospyris anthophora, Stichocorys subligata, Lophocyrtis nomas and Lithelius spp. The transitional assemblage represents relatively low values of productivity and species richness, and consists of three dominant species of T. anthophora, S. subligata and L. nomas. The characteristics of the early Miocene assemblage are relatively low productivity, but high species richness. The two dominant species present in this assemblage are T. anthophora and Cyrtocapsella tetrapera. The most significant faunal turnover of radiolarians is marked at the boundary between the transitional/early Miocene assemblages. We also reviewed changes in other microfossil assemblages in the low latitudes during the late Oligocene through early Miocene. The microfossil assemblages of major groups show sequential changes near the Oligocene/Miocene (O/M) boundary (23.8 Ma). Many extinction events and some first occurrences of calcareous nannofossils and many occurrences of radiolarians are found from about 24.8 to 23.3 Ma, and first occurrences of planktic foraminifers and diatoms followed from 23.2 through 22 Ma. Hence, the O/M boundary is identified as a significant level for microfossil evolutions.

Early Middle Jurassic (late Aalenian) radiolarian assemblage in a manganese nodule from the Northern Chichibu Belt in the Ino area, Kochi Prefecture, Southwest Japan

Well-preserved radiolarians were obtained from a manganese nodule collected from the Northern Chichibu Belt in the Ino area, Kochi Prefecture, Southwestern Japan. This is the first discovery of manganese nodules containing radiolarians in the Chichibu Belt. The radiolarian assemblage in the manganese nodule consists of 111 nassellarians and 110 spumellarians. The assemblage contains 38 described species and 43 unknown morphotypes as shown by Yao [Yao, A., 1997. Faunal change of Early–Middle Jurassic radiolarians. News of Osaka Micropaleontologists, Special Volume, no. 10, 155–182 (in Japanese with English abstract)]. The assemblage suggests the late Aalenian age based on the biostratigraphic data in Japan and the Western Pacific. It shows a low diversity of ring and disc shaped spumellarians like the genera Hexasaturnalis, Parasaturnalis and Orbiculiforma. The genera Paronaella, Parvicingula and Parahsuum are highly diversified. Faunal composition of the examined assemblage in the Chichibu Belt is different from the contemporaneous assemblages in the Mino and Kuzumaki–Kamaishi Belts. This difference seems to indicate that the depositional regions of manganese nodules are different among the Chichibu, Mino and Kuzumaki–Kamaishi Belts. The examined manganese nodule may have been deposited during late Aalenian time in a higher latitudinal area than its present location in the Kuzumaki–Kamaishi Belt judging by the number of species belonging to Parvicingula.

Middle and Upper Devonian radiolarian faunas from Chiang Dao area, Chiang Mai province, northern Thailand

Abstract Diverse and significant well-preserved radiolarians were obtained from ribbon-bedded chert in an area to the north of Chiang Dao city, Chiang Mai, northern Thailand. The area is mainly composed of an accretionary complex, which is recently considered as a key part of a newly described suture zone in the Southeast Asian region. Devonian radiolarian-bearing cherts are exposed within this area. These cherts contain identical radiolarian faunas, which include nine families and forty-three species belonging to thirteen genera. Among these faunas, Entactinaria are dominant. Three new species, Trilonche chiangdaoensis, Trilonche dihelicis and Trilonche vachardi, are erected and about thirty species, which have never been reported from Thailand, are also present. The Trilonche minax (lower Frasnian) radiolarian assemblage from Australia is recognized in the area. The radiolarian faunas are systematically described and relationships between them and fauna from adjacent radiolarian provinces are discussed....

LONGOBARDIAN (MIDDLE TRIASSIC) ENTACTINARIAN AND NASSELLARIAN RADIOLARIA FROM THE DINARIDES OF BOSNIA AND HERZEGOVINA

Abundant and well-preserved radiolarians are reported from a limestone sample taken from near the town of Fojnica, southern Bosnia and Herzegovina. A late late Ladinian age is assigned to this sample based on the index species Spongoserrula fluegeli and Muelleritortis cochleata and associated radiolarian fauna. As a result of taxonomic studies on the entactinarian and nassellarian fauna of this sample, three species ( Pseudostylosphaera multispinata, P. oblonga, and P. procera) from the suborder Entactinaria, and 18 species (Bulbocyrtium cordeyi, B.? longobardicum, Goestlingella goricanae, G. pseudoillyrica, Monicasterix ornata, M. parvisegmentata, M. pulchra, Nabolella brevispinosa, N. crenulata, N. trispinata, Ladinocampe dinarica, Spinotriassocampe praecarnica , Pseudosaturniforma ladinica , Pararuesticyrtium coniformis , P.? sanfilippoae , Conospongocyrtis bragini, Castrum blomei, and Triassocyrtium longum) from the suborder Nassellaria are described as new. Moreover, the genus Pseudosaturniforma is emended based on the new materials.

Middle and Upper Devonian radiolarian faunas from Chiang Dao area, Chiang Mai province, northern Thailand

Diverse and significant well-preserved radiolarians were obtained from ribbon-bedded chert in an area to the north of Chiang Dao city, Chiang Mai, northern Thailand. The area is mainly composed of an accretionary complex, which is recently considered as a key part of a newly described suture zone in the Southeast Asian region. Devonian radiolarian-bearing cherts are exposed within this area. These cherts contain identical radiolarian faunas, which include nine families and forty-three species belonging to thirteen genera. Among these faunas, Entactinaria are dominant. Three new species, Trilonche chiangdaoensis, Trilonche dihelicis and Trilonche vachardi, are erected and about thirty species, which have never been reported from Thailand, are also present. The Trilonche minax (lower Frasnian) radiolarian assemblage from Australia is recognized in the area. The radiolarian faunas are systematically described and relationships between them and fauna from adjacent radiolarian provinces are discussed. These cherts with their radiolarian faunas are evidence for the presence of a wide paleo-ocean once existed between Shan-Thai and Indochina continental terranes.

Late Triassic (Early to Middle Norian) radiolarians from the Antalya Nappes, Antalya, SW Turkey

Abstract. The Gökdere Formation of the Alakircay Nappe (Antalya Nappes) mainly consists of cherty limestone and limestone with calciturbidite intercalations. Moderately to well-preserved radiolarians were obtained from the Gökcam section of the Gökdere Formation located to the west of Antalya City, southwestern Turkey. The radiolarians of the Gökdere Formation obtained in this study are comparable to the faunas described from the Queen Charlotte Islands, British Columbia and the Antalya Nappes, southwestern Turkey. The age range of the radiolarians is late Early Norian to early Middle Norian based on the co-occurrence of Capnodoce serisa, Harsa siscwaiensis, Xiphosphaera fistulata and an associated fauna. Three species (Nodocapnuchosphaera altineri, Renzium whalenae and Enoplocampe(?) norica) and one subspecies (Kinyrosphaera helicata goekcamensis) are defined as new.