Norian Research Articles

A Late Triassic flora from east-central Axel Heiberg Island, Nunavut, Canada

A new floral assemblage is described from the Fosheim Member of the Heiberg Formation on southern Axel Heiberg Island. The flora is relatively diverse, consisting of at least 10 different collected species and three field-identified species from a single small locality. The flora has some similarities to other European–Sinian floras, such as those previously found on Axel Heiberg and Ellesmere islands and in Scoresby Sound of eastern Greenland. The largest difference from previously described floras is the dominance of the bennettitalean Pterophyllum astartense, suggesting a drier climate in contrast to the more humid one previously proposed. The presence of Lepidopteris ottonis places the flora within the Upper Triassic Lepidopteris zone, suggesting a Norian age.

AGE AND GEOCHEMISTRY OF MIDDLE TO LATE CARNIAN BASALTS FROM THE ALAKIRÇAY NAPPE (ANTALYA NAPPES, SW TURKEY): IMPLICATIONS FOR THE EVOLUTION OF THE SOUTHERN BRANCH OF NEOTETHYS

The geochemical features of spilitic basalts and the radiolarian fauna of associated pelagic sediments have been studied from two different sections of the Alakircay Nappe of the Antalya Nappes, SW Turkey. The first section in Cukurkoy is located in the eastern part of the Antalya Gulf and includes thick spilitic basalts, overlain by an alternation of mudstone, marl and pelagic cherty limestone. Radiolarian data from the cherty limestone in this unit reveals a middle Carnian age for this section. The second section in Yaylakuzdere is situated in the western part of the Antalya Gulf. In this section, thick pillow basalts are overlain by a succession of limestone/cherty limestone and shale beds. The age of the limestones interlayered with the pillow basalts was assigned to the late Carnian, whereas the basal part of the overlying cherty limestones was dated as latest Carnian/earliest Norian by conodont and radiolarian faunas. The pillow lavas in the Cukurkoy and Yaylakuzdere regions consist of within-plate type alkaline basalts and display multi-element pattern similar to typical oceanic island basalts (OIB). Low La/Yb, Zr/Y and La/Nb < 1 ratios are also indicative for an OIB-like deep mantle source. These alkaline basalts have not suffered interactions with a subducted slab and/or continental crust due to presence of high HFSE abundance, the lack of depletion in Nb and Ta that are characteristics of subduction and/or crustal contamination processes. Based on this data, it can be concluded that alkaline volcanism in these two regions of the Antalya Nappes have been probably generated by a small OIBtype mantle plume during the middle - late Carnian time interval, in the advanced stages of rifting of the Antalya Nappes successions in the southern branch of Neotethys. This data reveals the generation of a rift basin before middle Carnian for this ocean.

Vallesaurus cenensis wild, 1991, A drepanosaurid (reptilia, diapsida) from the Late Triassic of Northern Italy

Vallesaurus cenensis, a small drepanosaurid reptile from the Norian (Late Triassic) beds of the Calcare di Zorzino (Zorzino Limestone) is described. The holotype and only known specimen represents the first drepanosaurid in which the skull is preserved articulated with the postcranial skeleton. The study of Vallesaurus anatomy confirms previous data about arboreal adaptation in all known drepanosaurids and permits more firm hypotheses about the phylogenetic relationships of the Drepanosauridae to be proposed.

High-precision U-Pb zircon age from the Triassic of Italy: Implications for the Triassic time scale and the Carnian origin of calcareous nannoplankton and dinosaurs

The Triassic time scale is poorly constrained due to a paucity of high-precision radiometric ages. We present a 206 Pb/ 238 U age of 230.91 ± 0.33 Ma (error includes all known sources) for zircon from an ash bed in the upper Carnian (Upper Triassic) of southern Italy that requires a major revision of the Triassic time scale. For example, the Norian stage is lengthened to more than 20 m.y. The section containing the ash bed is correlated with other Tethyan sections and, indirectly, with the Newark astronomical polarity time scale (APTS). The dating provides also a minimum age for some important climatic and biotic events that occurred during the Carnian. We note a coincidence between these events and the eruption of the large igneous province of Wrangellia, but the possible link between volcanism and climatic and biotic events requires further scrutiny.

Biogeography of the Late Triassic wallowaconchid megalodontoid bivalves

Discoveries of Late Triassic alatoform bivalves (family Wallowaconchidae) in Alaska and in south Asia and Arabia reveal a broad distribution for these tropical bivalves, overturning the concept of these bivalves being endemics of offshore island arc terranes in eastern Panthalassa. They occupied an area extending from central Tethys to the eastern Pacific margin of Panthalassa. The Tethyan wallowaconchids occur in nearshore environments on the north margin of Gondwana, indicating an environmental tolerance for continental shelf settings in addition to their primary occurrence on isolated oceanic islands. The new sites reveal a taxonomic diversity among wallowaconchids. Wallowaconchids present in India are conspecific with Wallowaconcha raylenea, the type species of Wallowaconcha, whereas wallowaconchids in Arabia are an undescribed taxon and wallowaconchids in south-central Alaska are small in size and a different undescribed taxon. All known wallowaconchids are of Norian age and they appear to be a wide-ranging component of Late Triassic tropical biotas.

BRACHIOPODS FROM THE UPPER TRIASSIC REEF HABITATS OF THE NORTHERN CALCAREOUS ALPS (DACHSTEIN LIMESTONE, HOCHSCHWAB, AUSTRIA)

Upper Triassic brachiopods from 2 localities in the reef Dachstein Limestone of the SE Hochschwab massif in Styria, Austria are systematically described and illustrated. About 900 variably preserved specimens belong to 28 species, representing thus the most diverse brachiopod fauna known from the North Alpine Dachstein Limestone. This indicates that brachiopods were common inhabitants of reef habitats during the Alpine Norian. Oxycolpella , Sinucosta and Aulacothyropsis are dominant. Seven brachiopod species are known from the Kossen Formation (Rhaetian). Adygella biplicata (Dagys) and Ladinian Hungarispira loretzi (Bittner) are the newcomers in the Nordalpine Dachstein Limestone. In addition to brachiopods, only some fragments of bivalves were found. Conodonts of the species Epigondolella triangularis (Budurov 1972) indicate the Early Norian age.

STRATIGRAPHY AND PALYNOLOGY OF THE UPPER TRIASSIC NAYBAND FORMATION OF EAST-CENTRAL IRAN

A palynological study of the Nayband Formation (central eastern Iran) has been carried out in order to review and update its stratigraphic framework. In its type locality the formation crops out on the southern flank of Nayband Mountain, about 200 km south of Tabas. It consists of a thick, mixed siliciclastic-carbonate sequence subdivided into four members; in ascending order: the Gelkan Member (mainly shales and silstones), the Bidestan Member (marls, siltstones with minor sandstones and fossiliferous limestones), the Howz-e-Sheikh Member (sandstones and siltstones), and the Howz-e-Khan Member (sponge and coral dominated reefs alternating with marls and sandstones). Three palynological assemblages have been recognised; in ascending order: a) an assemblage characterised by the presence of Annulispora folliculosa and A. microannulata which allows the Gelkan Member and most of the Bidestan Member to be assigned an early Norian age; (b) an assemblage marked by the first occurrence of Polycingulatisporites mooniensis, which indicates the upper part of the Bidestan Member is mid-late Norian; c) an assemblage containing Classopollis chateaunovi in association with Retitriletes austroclavatidites, Gliscopollis meyeriana, Limbosporites lundbladii, Rugaletes awakinoensis and Callialasporites dampieri that allows the Howz-e-Sheikh Member to be assigned a Rhaetian age. The presence of some Eurasian and/or cosmopolitan forms in the Rhaetian microflora reflects the position of the Iranian plate on the southern margin of Eurasia.

BIOSTRATIGRAPHY OF UPPER TRIASSIC-LOWER JURASSIC CARBONATE PLATFORM SEDIMENTS OF THE CENTRAL-SOUTHERN APENNINES (ITALY)

The results of a biostratigraphic study on the Upper Triassic-Lower Jurassic carbonate platform sediments are outlined. Three stratigraphic successions cropping out in different areas were analysed: Monte Cefalo, (Aurunci Mts, southern Latium), Costa dei Frascari (Matese, northern Campania) and Monte Meta (Gran Sasso d’Italia, Abruzzi). The study of microfossil assemblages composed of benthic foraminifers and calcareous algae allowed identification of four biozones and one subzone. From the bottom upwards, the biostratigraphic units are: the Triasina hantkeni and Griphoporella curvata Zone; the Thaumatoporella parvovesiculifera Zone; the Palaeodasycladus mediterraneus Zone; the Valvulinidae and Rivulariaceae Zone; and the Orbitopsella Subzone. Besides, the lower part of the Costa dei Frascari section was referred to the portion of the Norian below the first occurrence of the Triasina hantkeni and Griphoporella curvata . These sediments are characterized by a rich assemblages mostly composed of pseudoudoteaceans algae, echinoderm remains, chaetetids and large gastropods. Microbiostratigraphic study of the Upper Triassic-Lower Jurassic sediments highlighted a similar succession of bioevents in all the sections analysed allowing precise bio- and chronostratigraphic correlations to be made. In contrast, the paleoecological data obtained from biofacies analysis combined with lithological features observed in coeval units point to different depositional environments, reflecting time and space variation within the context of a single, large carbonate platform. In fact, both sedimentation, and the observed associations of organisms, were controlled by chemical-physical factors connected to variations in water energy and water circulation. Instead, in other cases tectonics and subsidence seem to have played an essential role.

A new species of the Late Triassic aetosaur Desmatosuchus (Archosauria: Pseudosuchia)

Reanalysis of known armor of the stagonolepidid (aetosaur) Desmatosuchus has shown distinct differences in the lateral armor among individuals known from Carnian and Norian age rocks in the southwestern United States. Combined with previously reported cranial differences it is apparent that Norian specimens of Desmatosuchus represent a species distinct from the type species Desmatosuchus haplocerus and are described herein as Desmatosuchus smalli n. sp. D. smalli is known solely from Norian age rocks, whereas D. haplocerus is known only from Carnian age rocks. The separation of Desmatosuchus into distinct Carnian and Norian species suggests some biostratigraphic utility for these taxa. To cite this article: W.G. Parker, C. R. Palevol 4 (2005) .

Um Novo Horizonte de Correlação para o Triássico Superior do Rio Grande do Sul

A new biozone - called Ictidosaur Assemblage Zone - is proposed to the Upper Triassic Caturrita Formation from Southern Brazil, based on the discovery of a distinct tetrapod association characterized by the presence of little non-mammalian cinodonts including Riograndia guaibensis, Brasilodon quadrangularis and Brasilitherium riograndensis. Besides, the advanced procolophonid Soturnia caliodon, the dinosaur Guaibasaurus candelariensis, the dicynodont Jachaleria candelariensis, indeterminated phytosaurs and sphenodontids were also found in this association. The new biozone overlies the Rhynchosaur Assemblage Zone and encloses the “Jachaleria Level” usually cited for these layers. Stratigraphical sections, as well as facies analysis, facies associations and architectural elements confirms that the new biozone is clearly included in a distinct stratigraphical level, which reflects a marked change in the fluvial pattern of the sequence. The anastomosed/meandering pattern associated to the underlying Rhynchosaur Assemblage Zone turns to a braided to low confinement fluvial system with unconfined flows. The faunal and faciological changes may have been caused by a combined action of climatic, base level and floral changes, probably reflecting the global tendency to an increasing aridity towards the end of the Triassic. It is presumed an early Norian age for the new biozone on basis on its faunal content, on its stratigraphic placement, recovering the Carnian rhynchosaur assemblage and also on the presence of woods, leafs and reproductive structures of conifers, whose morphological pattern is exclusively Triassic.

A COMPLETE SPECIMEN OF MYSTRIOSUCHUS (REPTILIA, PHYTOSAURIA) FROM THE NORIAN (LATE TRIASSIC) OF LOMBARDY (NORTHERN ITALY)

A complete and nearly articulated new phytosaur specimen is described in detail. The skeleton, about 4 metres long, has been collected from the uppermost level of the Calcare di Zorzino (Norian, Upper Triassic) in the small quarry of Endenna (Bergamo, Northern Italy). Available characters of the skull allow assignment of this long snouted, uncrested phytosaur to Mystriosuchus planirostris Von Meyer 1863. The postcranial anatomy, detailed here for the first time for this species, suggests a stronger adaptation to aquatic life in Mystriosuchus than in other phytosaurs, and may increase available data to improve our knowledge of the systematic relationships among phytosaurs. The discovery of this nearly complete skeleton in a marine intraplatform basin suggests that a short post-mortem transport of the carcass occurred and thus this phytosaur may have lived whether in a fresh water environment or in a shallow marine habitat, close to emerged lands.

LATE TRIASSIC (LATE NORIAN-RHAETIAN) RADIOLARIANS FROM THE ANTALYA NAPPES, CENTRAL TAURIDES, SOUTHERN TURKEY

The Hocakoy section measured from the Alakircay Nappe (middle nappe) of the Antalya Nappes contain rich radiolarian fauna ranging from late Norian (Late Triassic) to middle-late Cenomanian (mid Cretaceous). At the basal part of the section, the Late Triassic (late Norian-Rhaetian) Gokdere Formation is characterized by gray to beige cherty limestone at the base and pinkish red chert- gray to beige limestone alternation at the top, with moderately to well-preserved radiolarians in the red chert beds. The overlying Jurassic - Middle Cretaceous Hocakoy Radiolarite is mainly represented by chert-mudstone alternations with some limestone interlayers. Radiolarians of the Gokdere Formation can be well correlated with that of the fauna from the Mino Terrane, central Japan and the fauna from the Queen Charlotte Islands, British Columbia, Canada. Four radiolarian zones from central Japan are recognized in the fauna obtained from Gokdere Formation such as “ Praemesosaturnalis multidentatus Lowest Occurrence Zone (TR8A)” (late Norian), “Praemesosaturnalis pseudokahleri Lowest Occurrence Zone (TR8B)” (late Norian), ? “ Skirt F lowest Occurrence Zone (TR8C)” (late Norian-Rhaetian) and partly “ Haeckelicyrtium breviora Taxon Range Zone (TR8D)” (Rhaetian). In comparison with the Queen Charlotte fauna, the two zones “ Betraccium deweveri Zone” (late Norian) and “ Proparvicingula moniliformis Zone” (early Rhaetian) are also encountered in the Gokdere Formation. Radiolarians of the uppermost part of the Gokdere Formation indicate that “ Globolaxtorum tozeri Zone” defined in Queen Charlotte Islands corresponding to the late Rhaetian, is not present in the section. Five new taxa, Capnuchosphaera okayi , Bistarkum rhaeticum , Praemesosaturnalis heilongjiangensis aksekiensis, P. nobleae , Veghicyclia sanfilippoae were determined within the late Norian-Rhaetian radiolarian fauna of the Gokdere Formation in Hocakoy section.

Evolution of Qinling Mianlue Belt: Evidence from Sedimentology and Tectonics of the Northern Yangtze, China

Evolution of Qinling Mianlue Belt: Evidence from Sedimentology and Tectonics of the Northern Yangtze, China

TAXONOMY AND FAUNAL AFFINITY OF LATE CARNIAN ­ RHAETIAN CONODONTS IN THE SOUTHERN CHICHIBU BELT, SHIKOKU, SW JAPAN

Conodonts from the latest Carnian - Middle Norian pelagic limestone and Late Norian - Rhaetian bedded chert-section at Hisaidani, southern Chichibu Belt, Shikoku, SW Japan, are described. Taxonomy of conodont-genera Metapolygnathus Hayashi, Ancyrogondolella Budurov, Mockina Kozur and Misikella Kozur & Mock is discussed. Middle Norian Mockina sakurae n. sp., M. shamiseni n. sp. and Late Norian M. hisaidaniensis n. sp. are described. The affinities of the Hisaidani - fauna are rather Tethyan. The Early - Middle Norian conodont-association at Hisaidani is dominated by Ancyrogondolella spatulata (Hayashi). Towards the Middle and Late Norian, affinities with Pacific taxa are present. The three new species provide also a provincial character that typifies the pre-accretionary Izanami plateau from which the rocks of Hisaidani were derived.

3 - SOUTHERN TUSCANY - A - ARGENTARIO PROMONTORY

The Argentario Promontory consists of a complex stack of Tuscan, Ligurian and Ligurian-Piedmontese Units (Lazzarotto et al., 1964; Decandia and Lazzarotto, 1980). From bottom to top they are (Fig. 1): 1. Monticiano-Roccastrada Unit. It comprises, from bottom to top: a- Mt. Argentario Formation. Graphitic phyllites with metasiltstone interbeds grading upwards into grey-whitish quartzites and metaconglomerates, with local graphite-rich phyllitic intercalations. This formation has been correlated to the Upper Carboniferous-Lower Permian successions cropping out along the Mid Tuscan Ridge (e.g. the St. Lorenzo Schists of the Pisani Mts. and Iano Schists and Sandstones) and in eastern Elba (Rio Marina Fm.). b- “Verrucano”. Alternating violet and greenish phyllites with local carbonate nodules and levels (caliche), quartzites and quartzitic white-pink metaconglomerates of Late Ladinian?- Carnian age. This succession, which shows an overall fining- and thinning-upward trend (including many metric/decametric positive cycles), is related to continental braided rivers passing upward to a coastal plain environment (Uncini, 1985). In the syntectonic quartz-rich segregations of the “Verrucano” rocks, Theye et al. (1997) found Mg-carpholite which testifies a HP-LT event (P> 8kb T = 300-400°C). c- Tocchi Formation. It consists of vacuolar, polymictic breccia made up of yellowish carbonatic and grey to green phyllitic clasts. These diagenetic and/or tectonic breccias derive from Carnian siliciclastic-carbonatic lithotypes which constitute the transition from the continental “Verrucano” and the Norian carbonatic shelf deposits. 2. Tuscan Nappe. This non-metamorphic unit is constituted by the “Calcare Cavernoso”: grey and dark grey, vacuolar calcareous and calcareous-dolomitic breccias with local karst structures. At places, these breccias include boulders and slices of stratified calcareous-dolomitic successions. Cataclastic textures are frequently recognisable. 3. Cala Piatti Unit. It is made up of Triassic recrystallised carbonate succession: a. Lower?-Middle Triassic stratified grey-pinkish limestones, b. Middle-Upper Triassic stratified black limestones, c. Upper Triassic? massive or poorly bedded grey dolostones. This succession represents one of the rare evidence of Early?-Middle Triassic marine sedimentation in the Northern Apennines (see also the Punta Bianca-Massa succession: Martini et al., 1986). 4. Cala Grande Unit. It is made up of HP-LT metamorphic rocks. In particular, two lithologic associations are recognisable: a. Varicoloured (reddish and grey-green) phyllites with grey and dark grey calcschists and recrystallised limestones; b. Metaophiolites (gabbros, basalts, serpentinites and ophiolitic breccias). Particularly, in b. HP-LP minerals are present: glaucophanitic amphibole (Mgriebeckite to crossite)+lawsonite+phengitic mica±Na-pyroxene (Gottardi, 1957; Ricci, 1972; Azzaro et al., 1977; Theye et al., 1997). The presence of Fe-carpholite relics within syn-tectonic quartz veins of the metasedimentary lithotypes (Theye et al., 1997) suggests T= 300-350°C and P>7 kb peak metamorphic conditions in agreement with the Blueschists facies minerals of the Metaophiolites. This unit was correlated to the “Schistes Lustres” of the Alpine Corsica (Ricci, 1972; Ricci and Serri, 1975). Polymictic tectonic breccias, mainly made up of elements and slices of “Calcare Cavernoso” and/or “Verrucano” (but locally also of the two uppermost units), separate the Tuscan Nappe from the overlying Cala Piatti Unit and this latter from the Cala Grande Unit. The complex tectonic stack of Mt. Argentario is related to the Oligo-Miocene compressional stage (which produced the piling up of the “Schistes Lustres” onto the Tuscan Units and the metamorphism of the Monticiano-Roccastrada Unit), but also to the post-compressional events (Burdigalian- early Tortonian) linked to the extensional tectonics of the Apennines and the Tyrrhenian Sea area (Bartole, 1995; Carmignani et al., 1995, cum bibl.). During the extensional events, the tectonic lamination of the Tuscan Nappe through low-angle normal faults, and the formation of the Mt. Argentario polymictic breccias occurred.

Upper Triassic reef facies in the Asher-Atlit-1 borehole, Northern Israel: Microfacies, cement stratigraphy and paleogeographic implications

The late Triassic succession of the Asher-Atlit 1 borehole is over 1000 m thick, and is composed of reefal and associated facies interbedded with volcanics of Norian age. Only borehole cuttings are available. Microfacies classification and cement stratigraphy determined by optical and CL microscopy, allowed discrimination of six episodes of reef establishment, progradation, shallowing, and termination. Organic buildups are constructed of reef-building biota (sponges, possible corals, encrusting organisms) typical for the late Triassic of the Tethys. Reef-associated facies include fore-slope, central reef, ooid shoal, lagoonal, and supratidal environments. Cement zoning patterns trace diagenetic signatures which range from early neomorphic skeletal replacements and original marine cements, via characteristic burial sequences; depositional and diagenetic sequences are terminated by marginal marine intra- or supratidal conditions, and subaerial exposure with pedogenic overprints. Volcanic episodes tend to be associated with termination of carbonate sedimentation episodes, while volcanic quiescence and subsidence permit vertical progradation of reefal and associated facies. The depositional and progradational environment, rapid rate of sedimentation, periodicity, association with volcanics, and regional considerations, suggest a depositional setting on the rifted shelf-margin of the nascent Neo-Tethys, with a possible eustatic overprint.

A NEW, EARLY CROWN-GROUP ASTEROID (ECHINODERMATA) FROM THE NORIAN (TRIASSIC) OF NORTHERN ITALY

Noriaster barberoi gen. et. sp. n. is based on a single specimen from the Calcare di Zorzino (Norian, Triassic) of northern Italy. A member of the surviving Poraniidae (Valvatida; Echinodermata), N. barberoi is the oldest-known species assignable to a Jurassic and younger family and the first such species known from the Triassic. No Paleozoic species with close affinities with crown-group families has been recognized. Noriaster and the slightly older Triassic genus Trichasteropsis from the Muschelkalk of Germany together indicate that the diversification of crown-group asteroids was well underway at least by Middle and Late Triassic time. Phylogeny of crown-group asteroids is problematic because extant familial-level taxa are morphologically divergent, and they exhibit comparatively few uncontested characters that clearly indicate phylogenetic affinities and sequence. Familial assignment of Noriaster is supported by a new cladistic analysis. To the student of living asteroids, the appearance of a living Noriaster would be remarkable only because it would seem so commonplace. To the extent that form correlates with function, Noriaster suggests that modern asteroid life modes emerged quite promptly during the Mesozoic asteroid diversification.

A LATE TRIASSIC OSTRACOD ASSEMBLAGE FROM THE QUATTERVALS NAPPE (AUSTROALPINE, NORTHERN ITALY)

The up to 1200 m thick Norian succession of the Quattervals Nappe (Central Austroalpine, Italy) documents a tectonically-driven passage from intertidal facies (Dolomia Principale-Hauptdolomit), represented by early-dolomitized bedded to massive gray dolostones, to intraplatform basin sediments (Pra Grata Formation and Quattervals Limestone), consisting of resedimented dark limestones and thin bedded laminated limestones, alternating (mainly in the Pra Grata Formation) with intraformational breccias containing abundant shallow-water facies. The transitional and basinal facies contain an interesting ostracod assemblage, beside bioclastic layers containing shallow-water and upper slope skeletal grains.The ostracod fauna is rich in specimens belonging to few genera, denoting restricted environmental conditions characterized by variations of salinity and low oxygenation. Despite the intense deformation and recrystallization related to the Alpine tectonics, the paleontological analysis of the ostracod assemblage from the base of the Quattervals Limestone, allowed the identification of the two new species of ostracods Rhombocythere dimorphica and Kerocythere quattervalsi in association with other already known forms.

Magnetostratigraphy of the Kavaalani section (southwestern Turkey): Consequence for the origin of the Antalya calcareous nappes (Turkey) and for the Norian (Late Triassic) magnetic polarity timescale

A magnetostratigraphic study of the Kavaalani section of uppermost Carnian to Upper Norian age, located in the Antalya Calcareous Nappes (southwestern Turkey), reveals nineteen polarity intervals. This pattern correlates very well with two other polarity sequences obtained from the same nappe system (Bolücektasi Tepe and Kavur Tepe) if these sections were deposited in the same (northern) hemisphere. This new interpretation changes our previous conclusions regarding the southern hemisphere origin of the magnetic remanence of the Kavur Tepe section. The paleomagnetic data obtained from the Kavur Tepe and the Kavaalani sections therefore reflect large (∼180°) internal rotations within the Antalya nappes. These nappes were likely formed close to the northern tip of the Arabian promontory. We propose a revised yet still preliminary version of the Norian magnetic polarity sequence.

Triassic pelagic deposits of Timor: palaeogeographic and sea-level implications

In West Timor, Triassic deposits are found in the Parautochthonous Complex, as well as in the Allochthonous series of Sonnebait. A detailed biostratigraphic investigation, integrating field observations and facies analysis, allowed the reconstruction of a synthetic lithostratigraphic succession for the Upper Triassic; a stratigraphic transition from Carnian shales to Upper Norian–Rhaetian limestones is also shown by this study. The fossil content predominantly originates from an open marine environment; lithostratigraphic Units A–E are dated on the basis of radiolaria and palynomorphs, and Unit H, on ammonites and conodonts. The presence of pelagic bioclasts, together with normal grading, horizontal laminations, and current ripples, is indicative of a distal slope to basin environment. The ammonite rich condensed limestone of Unit H was deposited on a ‘pelagic carbonate plateau’ exposed to storms and currents. The organic facies have been used as criteria for biostratigraphy, palaeoenvironmental interpretation, and sequence stratigraphy. The palaeontological analysis of the Triassic succession of West Timor is based on the investigation of radiolaria and palynomorphs, in the marls and limestones of Units A–E, and also on ammonites and conodonts in the condensed limestone of Unit H. Units A and B are Carnian (Cordevolian) in age, based on the occurrence of the palynomorph Camerosporites secatus, associated with ‘ Lueckisporites’ cf. singhii, Vallasporites ignacii, Patinosporites densus and Partitisporites novimundanus. Unit C is considered as Norian, on the basis of a relatively high percentage of Gliscopollis meyeriana and Granuloperculatipollis rudis. Unit D contains significant palynomorphs and radiolaria; the organic facies, characterized by marine elements, is dominated by the Norian dinocysts Heibergella salebrosacea and Heibergella aculeata; the radiolaria confirm the Norian age. They range from the lowermost Norian to the lower Upper Norian. Unit E also contains radiolaria, associated in the upper part with the well-known marker of the Upper Norian, Monotis salinaria. For Unit E, the radiolaria attest to a Lower to Upper Norian age based on the occurrence of Capnodoce and abundant Capnuchosphaera; the upper part is Upper Norian to Rhaetian based on the presence of Livarella valida. Finally, the blocks of condensed limestone with ammonites and conodonts of Unit H allowed the reconstruction of a synthetic stratigraphic succession of Upper Carnian to Upper Norian age. Our stratigraphic data lead to the suggestion that the Allochthonous complex, classically interpreted as a tectonic melange of the accretionary prism of the Island Arc of Banda, is a tectonically dismembered part of a Triassic lithostratigraphic succession.