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The Kamura section, located in the Chichibu Belt of Kyushu Island in southern Japan, contains a succession of uppermost Permian to Upper Triassic shallow-marine atoll sediments from the mid-Panthalassic Ocean. In the present study, carbonate microfacies, conodont biostratigraphy, and carbonate carbon isotopes were analyzed, making it possible to construct a detailed biochronological framework for the Triassic of the central Panthalassic region. A total of 14 conodont zones are recognized from the uppermost Changhsingian to the upper Norian. The Lower Triassic contains the Hindeodus parvus, Isarcicella isarcica, and H. postparvus zones (Griesbachian), the Neospathodus dieneri Zone (Dienerian), and the Novispathodus ex gr. waageni-Parachirognathus Zone (Smithian), while no evidence of the upper Lower Triassic Spathian substage was recovered at Kamura. The overlying Middle Triassic section consists of the Chiosella ex gr. timorensis-Cratognathus, ‘Paragondolella’ ex gr. alpina-Pg. ex gr. excelsa, Budurovignathus hungaricus, and B. mungoensis zones, followed in the Upper Triassic by the Quadralella tadpole-Gladigondolella malayensis, Q. lobata-Q. carpathica, Primatella cf. orchardi-Pr. permica, Epigondolella rigoi-‘Pg.’ hallstattensis, and E. ex gr. bidentata-Norigondolella steinbergensis zones. The exact stratigraphic intervals present at Kamura were refined through intercalibration of the conodont biozonation data with its δ13Ccarb profile, which shows a characteristic series of negative and positive excursions that correspond to well-established global reference profiles. The Permian–Triassic boundary is placed 0.20 m above the Mitai-Kamura formation contact (a reference datum corresponding to the end-Permian extinction horizon, = 0 m) based on the first appearance of H. parvus, and the Olenekian–Anisian boundary is placed 17.60 m above the reference datum based on the first appearance of Ch. ex gr. timorensis. Kamura carbonates were assigned to six fabric types and 17 microfacies. The microfacies succession records a deepening immediately following the end-Permian mass extinction, a strong shallowing during the mid to late Smithian, development of an unconformity spanning the entire Spathian, and minor sea-level fluctuations during the Middle and Late Triassic. The Spathian unconformity is attributed to a eustatic fall related to a sharp cooling event at or close to the Smithian–Spathian boundary that exposed the Kamura atoll. The subsequent resumption of shallow-marine sedimentation in the earliest Middle Triassic was probably due to continued thermal subsidence of the oceanic crustal basement beneath the atoll. The present work is the most complete analysis to date of the conodont biostratigraphic, carbon isotope chemostratigraphic, and eustatic records of the Triassic System in the central Panthalassic Ocean and should serve as a regional reference standard in the future.

We present recent study results of the Lower Triassic conodont succession from the Ganxi and Jianshi areas of Enshi city, western Hubei Province, South China, which were situated on a carbonate ramp at the northeastern margin of the Upper Yangtze Platform. Therein, the uppermost Permian to Lower Triassic succession is well exposed and yielded abundant conodonts. A total of nine conodont zones are differentiated: (1) Clarkina yini Zone, (2) Clarkina meishanensis Zone, (3) Hindeodus changxingensis Zone, (4) Hindeodus parvus Zone, (5) Hindeodus postparvus Zone, (6) Clarkina planata Zone, (7) Neoclarkina aff. discreta Zone, (8) Neospathodus dieneri Zone, and (9) Novispathodus waageni Zone. The Ns. dieneri M1, Ns. dieneri M2, and Ns. dieneri M3 Subzones have also been distinguished within the Ns. dieneri Zone, and the Nv. waageni eowaageni and Nv. waageni waageni Subzones are recognizable within the Nv. waageni Zone in Jianshi. Most of the zones occur in succession, but the C. planata Zone is a local ecozone reflecting deeper water biofacies during H. postparvus Zone time. In the Jianshi section, the Permian–Triassic boundary is placed at Bed 136-2 based on the appearance of Hindeodus parvus immediately above the disappearance of Changhsingian taxa, while the Induan–Olenekian boundary (IOB) is drawn at Bed 225 + 40 cm based on the first appearance of Nv. waageni eowaageni within the upper range of the Ns. dieneri Zone indices. The Enshi conodont zones overall correlate well with those recognized elsewhere in South China and worldwide.

The Guryul Ravine section in Kashmir, northern India is an important reference section for global Lower Triassic stratigraphy. Once a candidate Global Stratotype Section and Point (GSSP) for the Permian-Triassic Boundary (PTB), the section has attracted intense attention for the PTB beds, but few studies have concerned the entire Lower Triassic stratigraphy. As one of the most continuous marine Lower Triassic successions on the northern margins of Gondwana, the Guryul Ravine section provides an important conodont biostratigraphic yardstick for worldwide correlations. This study presents recent results of the Lower Triassic conodont zonation from the Guryul Ravine section. A total of 6500 elements including 1600 P1 elements were recovered. Ten conodont zones were recognized from the Griesbachian to Spathian: Hindeodus parvus, Isarcicella staeschei, Clarkina planata, Neoclarkina krystyni, Neospathodus dieneri, Ns. pakistanensis, Novispathodus waageni, Scythogondolella mosheri, Nv. pingdingshanensis, and Nv. abruptus – Nv. brevissimus zones. The PTB is placed within Bed 52 in Unit E2, 80 cm above the base of Unit E2, based on the first occurrence (FO) of H. parvus. The Induan–Olenekian boundary (IOB) is tentatively placed at the base of Member G according to the positive maximum δ13Ccarb values, but it could be slightly higher based on conodonts. The Smithian-Spathian boundary (SSB) is drawn at the top of Member H based on the FO of Nv. pingdingshanensis and the carbon mdpt(N3-P3). Several conodont taxa are newly recognized near the top of the study section where the conodont fauna is dominated by segminiplanate elements of the Neogondolellinae. Many of these age-diagnostic species have been identified in other sections around the world, and their occurrence in Guryul Ravine supports their potential for worldwide correlation. The conodont sequence erected from the study section corresponds well to those of South China (e.g. Meishan) and elsewhere worldwide. The newly established conodont zonation from Kashmir provides a high precision time-frame to consider biotic evolution and environmental change during the Early Triassic, a crucial period of Earth history.

Investigation of the end-Permian mass extinction (EPME) has been greatly facilitated by high-resolution conodont biostratigraphic studies. To date, however, a detailed biostratigraphic framework has been lacking for shallow-marine successions of the Tethys region. In the present study, we analyzed carbonate microfacies, conodont biostratigraphy, and carbonate carbon isotopes of the Yangou Quarry section, a shallow-marine EPME succession that accumulated on an isolated carbonate bank on the northern margin of the Yangtze Platform. Microfacies analysis yielded four facies and 8 microfacies that record a seawater deepening immediately following the EPME. Ooids were abundantly produced during the EPME and earliest Triassic mass extinction (ETME) but were replaced by microbial mats, algae, bivalves, and brachiopods during an earliest Triassic transgression. A total of three conodont zones are recognized from the uppermost Changhsingian to the lowermost Griesbachian, in ascending order, the Hindeodus praeparvus Zone, H. parvus Zone, and Isarcicella staeschei Zone. The EPME and PTB (Permian-Triassic boundary) horizons are marked by the first occurrences of H. praeparvus at 6.18 m and H. parvus at 6.57 m, respectively, above the base of the section. The conodont biostratigraphic framework of the Yangou Quarry section was refined through intercalibration with its δ13Ccarb profile. This section records two discrete negative carbon isotope excursions (CIEs) that are correlative with the EPME and ETME horizons, and that can be correlated with similar CIEs at Meishan D and other PTB sections globally. Our study provides the first integrated, high-resolution biochemostratigraphic framework for a shallow-marine PTB succession in the eastern Tethys region, which will facilitate paleoenvironmental studies of similar facies elsewhere as well as correlations with deeper-water facies.

The new conodont genusMagnigondolellais recognized based on specimens recovered from the Anisian (Middle Triassic) of British Columbia in Canada, and Nevada in the USA. This new genus encompasses problematic specimens with high carinas, which have recently been collectively referred to asNeogondolellaex gr.regalisMosher. Ten species from North America are herein assigned toMagnigondolellan. gen., including the eight new speciesM.alexanderi,M.cyri,M.julii,M.nebuchadnezzari,M.salomae,M. n. sp. A,M. n. sp. B, andM. n. sp. C, as well as the two existing speciesM.regalis(Mosher) andM.dilacerata(Golding and Orchard). Other species from the Tethys region are also tentatively assigned toMagnigondolellan. gen. Based on published records, the genus appears to range from the Spathian to the upper Anisian in North America. The recognition of eight new species from the Anisian significantly increases the conodont biodiversity of this period, which has previously been regarded as a time of low diversity. Although some of the species included withinMagnigondolellan. sp. have relatively long stratigraphic ranges, many have been identified in both British Columbia and Nevada, and therefore show potential for biostratigraphic correlation on a regional scale.

30 pages; International audience; The transition from the Smithian substage to the Spathian substage of the Olenekian stage of the late Early Triassic was a critical time marked by a series of biological and environmental changes during the multimillion-year recovery interval following the end-Permian mass extinction. However, the Smithian/Spathian boundary (SSB) does not yet have an agreed definition, a shortcoming that complicates high-resolution analysis of events during the Smithian-Spathian transition. Here, we review key biostratigraphic (i.e., ammonoid and conodont) studies of the Smithian and Spathian substages in historically important regions (e.g., the Canadian Arctic for the Boreal realm, western North America for the eastern Panthalassic Ocean) and more recently re-studied locations (e.g., Pakistan and India in the southern Tethys, South China in the eastern Tethys) as well as the carbon isotope chemostratigraphy of 29 major Smithian-Spathian sections globally. Key ammonoid genera (e.g., Wasatchites, Anasibirites, Glyptophiceras and Xenoceltites of the late Smithian, and Bajarunia, Tirolites and Columbites of the early Spathian), conodont species (e.g., Scythogondolella milleri, Novispathodus waageni, and Borinella buurensis of the late Smithian, and ‘Triassospathodus’ hungaricus, Neogondolella aff. sweeti, and Icriospathodus spp. of the early Spathian), and carbonate carbon isotope excursions provide appropriate markers for constraining the SSB. Use of the first occurrence of the conodont Novispathodus pingdingshanensis as a potential marker of the SSB is also discussed. Based on correlations of biostratigraphic and carbon isotope data globally, we propose to revise previous placements of the SSB transition in some sections. Finally, we show that the Smithian Thermal Maximum (STM; herein named) was middle Smithian in age and not correlative with the SSB, as inferred in some earlier studies, and that the SSB coincided with a subsequent major global cooling event.

Eight new species of the conodontNeogondolellaare described from the Anisian (Middle Triassic) of northeastern British Columbia. The subtlety of morphological variation in this conodont genus has hampered biostratigraphical correlation, but large, often independently dated collections have enabled the description ofN.cuneiforme,N.curva,N.hastata,N.dilacerata,N.indicta,N.panlaurentia,N.tenera, andN.vellicatan. spp. Several of these species are widespread, as specimens ofN.curva,N.hastata,N.indicta,N.panlaurentia,N.tenera, andN.vellicataare found in contemporary collections from Nevada, whereasN.panlaurentiahas also been recovered from the Canadian Arctic. This distribution promises to significantly improve correlation among Anisian sections in North America.

New isotopic ages have been obtained from euhedral, first-cycle zircon grains recovered from Rhaetian strata preserved at the Black Bear Ridge section in northeastern British Columbia. Two statistically significant populations are present: an older population ca. 224 Ma, and a dominant younger population ca. 205 Ma. The younger population includes a group of grains with a weighted average 206 Pb/ 238 U age of 205.2 ± 0.9 Ma, which is interpreted to represent the maximum depositional age of the sediment. Potential sources for the two populations are found in the Quesnel terrane in central British Columbia, implying close proximity between this terrane and the autoch­thonous North American margin during the Late Triassic. This is supported by geochemical and structural evidence. The implication that the Quesnel terrane was close to its present-day latitude during the Late Triassic is in conflict with older estimates of paleolatitude based on paleomagnetic and paleontological evidence. The age of 205.2 ± 0.9 Ma obtained from the youngest population of zircons is also consistent with recently published estimates for the age of the Norian-Rhaetian boundary.

The Early Triassic is a critical interval recording episodic climatic, environmental, and biotic events after the end-Permian mass extinction. A precise global timescale for this epoch is essential to understand the sequence of events during this crisis. The undefined Induan–Olenekian stage boundary (IOB), long disputed, is a crucial element in providing a high-resolution chronostratigraphic framework for the Lower Triassic. Here we report new conodont lineages from the Jianshi section, South China that may contribute to the definition of the IOB. In Jianshi, within a succession of nine conodont zones, a possible IOB is placed at Bed 225 + 40 cm based on the first occurrence (FO) of conodont subspecies Novispathodus waageni eowaageni. New collections include a total of 99 well-preserved Eurygnathodus costatus specimens from Bed 225 to Bed 241, and a single occurrence of Eu. hamadai? from Bed 226. The FO of Eu. costatus occurs in Bed 225 + 10 cm, 30 cm below N. w. eowaageni. The reconstructed ontogenetic series of Eurygnathodus costatus involves four growth stages (A → B → C → D) based on characteristics of the denticles (nodes or ridges), platform, basal cavity, margin profile, and crimp. These preserve ancestral characters that suggest a novel origin for the evolutionary lineage of the genus, namely from Sweetospathodus kummeli →Eurygnathodus costatus→Eu. sp. D → Eurygnathodus hamadai. Seven additional informal species of Eurygnathodus are differentiated as potential biostratigraphic markers. The FO of Eu. costatus may serve as an auxiliary marker for the IOB.

The taxonomy, diversity, evolutionary lineages, and stratigraphical distributions of Middle and early Late Triassic conodonts are reviewed and re-evaluated. Twenty-five genera are recognized in the Middle and early Late Triassic, including a new genus cited in open nomenclature. Of these, 24 genera are assigned to two families and seven subfamilies. The family Gondolellidae consists of the subfamilies Cornudininae, Epigondolellinae, Neogondolellinae, Novispathodinae, Paragondolellinae and Pseudofurnishiinae. The family Gladigondolellidae is monotypic, consisting of the subfamily Gladigondolellinae. The genus Neostrachanognathus is not assigned to any family or subfamily as its origin is unclear. Conodont provincialism was low in the early Anisian, but from the late Anisian faunistic differences started to increase and became stronger during the early Ladinian, reaching a peak around the mid-Ladinian. Provincialism remained strong until the earliest Carnian and changed to an all-Triassic low in the early Tuvalian. The provincialism between North America and Tethys rebounded on the specific level during the late Tuvalian. Diversities on generic and specific levels have been established, and two major conodont diversity cycles are recognized: the first ranges from the Bithynian (early Anisian) to the Julian (late early Carnian), and the second is restricted to the Tuvalian (late Carnian).

The chronostratigraphy of Guandao section has served as the foundation for numerous studies of the end-Permian extinction and biotic recovery in south China. Guandao section is continuous from the Permian–Triassic boundary to the Upper Triassic. Conodonts enable broad delineation of stage and substage boundaries and calibration of foraminifer biostratigraphy as follows. Changhsingian–Griesbachian: first Hindeodus parvus, and first appearance of foraminifers Postcladella kalhori and Earlandia sp. Griesbachian–Dienerian: first Neospathodus dieneri, and last appearance of foraminifer P. grandis. Dienerian–Smithian: first Novispathodus waageni and late Dienerian first appearance of foraminifer Hoyenella ex gr. sinensis. Smithian–Spathian: first Nv? crassatus and last appearance of foraminifers Arenovidalina n. sp. and Glomospirella cf. vulgaris. Spathian–Aegean: first Chiosella timorensis and first appearance of foraminifer Meandrospira dinarica. Aegean–Bithynian: first Nicoraella germanica and first appearance of foraminifer Pilammina densa. Bithynian–Pelsonian: after last Neogondolella regalis, prior to first Paragondolella bulgarica and first appearance of foraminifer Aulotortus eotriasicus. Pelsonian–Illyrian: first Pg. excelsa and last appearance of foraminifers Meandrospira? deformata and Pilamminella grandis. Illyrian–Fassanian: first Budurovignathus truempyi, and first appearance of foraminifers Abriolina mediterranea and Paleolituonella meridionalis. Fassanian–Longobardian: first Bv. mungoensis and last appearance of foraminifer A. mediterranea. Longobardian–Cordevolian: first Quadralella polygnathiformis and last appearance of foraminifers Turriglomina mesotriasica and Endotriadella wirzi. The section contains primary magnetic signature with frequent reversals occurring around the Permian–Triassic, Olenekian–Anisian, and Anisian–Ladinian boundaries. Predominantly normal polarity occurs in the lower Smithian, Bithynian, and Longobardian–Cordevolian. Predominantly reversed polarity occurs in the upper Griesbachian, Induan–Olenekian, Pelsonian and lower Illyrian. Reversals match well with the GPTS. Large amplitude carbon isotope excursions, attaining values as low as −2.9‰ δ13C and high as +5.7‰ δ13C, characterize the Lower Triassic and basal Anisian. Values stabilize around +2‰ δ13C through the Anisian to Carnian. Similar signatures have been reported globally. Magnetic susceptibility and synthetic gamma ray logs show large fluctuations in the Lower Triassic and an overall decline in magnitude of fluctuation through the Middle and Upper Triassic. The largest spikes in magnetic susceptibility and gamma ray, indicating greater terrestrial lithogenic flux, correspond to positive δ13C excursions. High precision U–Pb analysis of zircons from volcanic ash beds provide a robust age of 247.28 ± 0.12 Ma for the Olenekian–Anisian boundary at Guandao and an age of 251.985 ± 0.097 Ma for the Permian–Triassic boundary at Taiping. Together, the new U–Pb geochronology from the Guandao and Taiping sections suggest an estimated duration of 4.71 ± 0.15 Ma for the Early Triassic Epoch.

The Upper Carnian-Lower Norian (Upper Triassic) Luning Formation at Berlin-Ichthyosaur State Park (BISP) in central NV (USA) has been sampled using for the first time the bed-by-bed approach for ammonoids, pelagic bivalves, and conodonts, more than 60 years after its first description by Silberling (U.S. Geological Survey Professional Paper 322: 1–63, 1959). BISP is historically important for the definition of the uppermost Carnian of the North American Triassic chronostratigraphic scale and is known worldwide as one of the most important ichthyosaur Fossil-Lagerstatte because of its extraordinary record of 37 articulated, large-sized specimens of Shonisaurus popularis. Nearly 190 ammonoids were collected from two stratigraphic sections, documenting all the latest Carnian to Early Norian ammonoid faunas previously described by Silberling. Halobiids were collected from five levels, and the first report of conodonts from BISP includes faunas from 13 levels. The ~340-m thick Brick Pile section, the most complete in the study area, includes the uppermost Carnian Macrolobatus Zone, which provides conodont faunas of the lower primitia zone and Halobia septentrionalis. The 200-m thick lowermost Norian Kerri Zone, which begins 52 m above the Macrolobatus Zone, yields conodonts of the upper primitia zone in its lower part, together with H. cf. beyrichi and H. cf. selwyni. The ichthyosaur-bearing interval, whose stratigraphic position has been interpreted quite differently by previous authors, is documented in the uppermost Carnian Macrolobatus Zone and is characterized by rich Tropites-dominated ammonoid faunas and by the onset of Halobia. All models proposed by various workers to explain the unusual ichthyosaur record are discussed and an additional explanation for the main ichthyosaur-bearing bed is proposed. The new hypothesis is that a harmful algal bloom (HAB) may have been the trigger for the mass mortality recorded in this level. Although the C/N boundary in the Brick Pile section lies within a 52 m interval that presently lacks paleontologic data, this succession is included in a small group of sections that are expected to contribute to the definition of the GSSP of the Norian stage. Correlation of the Brick Pile section with the best Carnian/Norian sections in northeastern British Columbia is discussed. Compared to the British Columbia Juvavites Cove and the GSSP candidate Black Bear Ridge sections, the Brick Pile section exhibits an ammonoid and Halobia record that is slightly more similar to that of the Tethyan sections. Correlation of the Brick Pile section with the second GSSP candidate Pizzo Mondello (Sicily, Italy) well demonstrates the significant problems encountered in calibration of the Tethyan and North American scales.

The First Appearance Datum (FAD) of the conodont Chiosella timorensis has been recently proposed as an index for the worldwide recognition of the Olenekian-Anisian Boundary (OAB, Early-Middle Triassic boundary). We here report the co-occurrence of C. timorensis with the ammonoids Neopopanoceras haugi (Hyatt and Smith), Keyserlingites pacificus (Hyatt and Smith), Subhungarites yatesi (Hyatt and Smith) and Pseudacrochordiceras inyoense (Smith), which are diagnostic of the late Spathian Haugi Zone. This shows that the previously published first occurrences of C. timorensis were still too poorly constrained, and it questions the adequacy of its FAD as a marker of the OAB. It challenges the significance of some observed lower stratigraphic occurrences of C. gondolelloides compared with C. timorensis. We revise the current criterion for the taxonomic separation of these two species and define a new Chiosella species (left in open nomenclature). The origin of Chiosella timorensis remains unknown but multi-element analyses suggest an affinity with the late Olenekian Neogondolella ex gr. regalis. Our reassessment of the material from the most important OAB sections (Desli Caira, Romania and Guandao, China) allows us to propose a new and more reliable biochronological scheme based on conodont maximal associations for the OAB.

The Jesmond succession of the Cache Creek Terrane in southern British Columbia records late Early Triassic peritidal carbonate sedimentation on a mudflat of a buildup resting upon a Panthalassan seamount. Conodont and foraminiferal biostratigraphy dates the succession as the uppermost Smithian to mid-Spathian. The study section (ca. 91 m thick) is dominated by fine-grained carbonates and organized into at least 12 shallowing-upwards cycles, each consisting of shallow subtidal facies and overlying intertidal facies. The former includes peloidal and skeletal limestones, flat-pebble conglomerates, stromatolitic bindstones, and oolitic grainstone, whereas the latter consists mainly of dolomicrite. The scarcity of skeletal debris, prevalence of microbialite, and intermittent intercalation of flat-pebble conglomerate facies imply environmentally harsh conditions in the mudflat. The study section also records a rapid sea-level fall near the Smithian-Spathian boundary followed by a gradual sea-level rise in the early to mid-Spathian.

The origin of jaws remains largely an enigma that is best addressed by studying fossil and living jawless vertebrates. Conodonts were eel-shaped jawless animals, whose vertebrate affinity is still disputed. The geometrical analysis of exceptional three-dimensionally preserved clusters of oro-pharyngeal elements of the Early Triassic Novispathodus , imaged using propagation phase-contrast X-ray synchrotron microtomography, suggests the presence of a pulley-shaped lingual cartilage similar to that of extant cyclostomes within the feeding apparatus of euconodonts (“true” conodonts). This would lend strong support to their interpretation as vertebrates and demonstrates that the presence of such cartilage is a plesiomorphic condition of crown vertebrates.

New detrital mineral age and whole-rock geochemical data provide the first constraints on the composition and source of North American Triassic strata in the northern Canadian Cordillera. Conodont-bearing Triassic strata collected from five locations across west-central to southeastern Yukon contain trace-element ratios ((La/Yb)N = ∼8; Eu/Eu* = ∼0.66), εNd(248 Ma) values (–9 to –10), and detrital zircon ages (400–680, 980–1200, 1500–1650, 1800–2000 Ma) that correspond with those of coeval rocks in the Canadian Arctic Islands and the Western Canada Sedimentary Basin of British Columbia and Alberta. The majority of detrital zircons were cannibalized from Ellesmerian clastic wedge and western Laurentian margin strata and recycled into Triassic rocks. Conspicuous early Paleozoic and Neoproterozoic detrital zircons may have been ultimately derived from allochthonous rocks of Caledonian–Baltican affinity in northern North America, such as the Pearya and Arctic Alaska – Chukotka terranes. One Early Triassic unit in eastern Yukon contains ca. 360 Ma detrital muscovite, and samples from several localities include single-grain occurrences of Mississippian detrital zircon. Mississippian detrital mineral ages likely record a partial source from mid-Paleozoic rocks of the allochthonous Slide Mountain and Yukon–Tanana terranes following their Late Permian – Early Triassic emplacement onto the Cordilleran margin. More substantial evidence of terrane-derived sediment deposited along the North American margin may be further identified within Triassic strata that are exposed to the west (outboard) of our sample sites, immediately adjacent to the Slide Mountain and Yukon–Tanana terranes.

The Sulphur Mountain Formation in the Wapiti area is subdivided into the Phroso, Meosin Mountain (new), and Vega members, which collectively span much of the Lower Triassic. The Smithian conodont faunas are particularly well developed and form the basis of three partly new conodont zones and two new subzones: the lachrymiformis Zone, meeki Zone, and mosheri Zone, with the last subdivided into the phryna and milleri Subzones. An informal lowermost Smithian nepalensis interval is introduced, although it has yet to be found in the area. The Phroso Member is latest Griesbachian, Dienerian, and, in its uppermost part, Smithian, specifically the lachrymiformis and meeki zones: these are shown to be equivalent to the Euflemingites romunduri ammonoid Zone. The Meosin Mountain Member is assigned to the meeki Zone in its lower part and the phryna Subzone of the mosheri Zone in its upper part: at least, the upper part of the mosheri Zone is equivalent to the Anawasatchites tardus ammonoid Zone. The Mackenzie Dolomite Lentil is at least partly older than the Meosin Mountain Member, and age equivalence of subsurface turbidite units in the Montney Formation should not be assumed. The lowermost Vega Member is also assigned to the phryna Subzone, and higher parts of that member span both the milleri Subzone of the Smithian and the entire Spathian. The following new conodont taxa are described: Neogondolella ? joanae , Novispathodus latiformis , Scythogondolella lachrymiformis , Sc. phryna , and Sc. rhomboidea ; several other new species are kept in open nomenclature.

Whitehorse trough is a frontier basin in south-central Yukon that is thought to contain gas and possibly oil. It consists of up to 7000 m of sedimentary and volcanic rocks referred to as the Lewes River Group (Triassic), Laberge Group (Jurassic), and Tantalus Formation (Jura-Cretaceous). The Lewes River Group is informally subdivided into the Povoas and Aksala formations, and the Laberge Group is informally subdivided into the Richthofen, Nordenskiold and Tanglefoot formations. To evaluate the petroleum source-rock potential of this basin, over 600 samples from the Aksala, Richthofen, Tanglefoot and Tantalus formations from throughout the trough have been analyzed by Rock-Eval programmed pyrolysis and combustion and by study of thermal alteration indicies (TAI) of palynomorphs, conodont alteration indicies (CAI), and vitrinite reflectance. The Povoas and Nordenskiold formations were not sampled because they consist of volcanic and volcaniclastic rocks, respectively, and have no source rock potential. The analyses indicate that the Aksala formation is a poor source rock that is postmature with no hydrocarbon potential. The Richthofen formation is a poor source rock that is postmature with minor gas potential. The Tanglefoot formation is a good source rock that is immature to early mature and gas-prone. The Tantalus Formation is also a good source rock that is immature to early mature and gas-prone. The Tanglefoot and Tantalus formations contain petroleum fluid inclusions that were probably generated from within these units. The inclusions reveal homogenization temperatures of mostly between 75–115°C and reveal several distinct, but minor pulses of liquid petroleum (mainly 19–21°API, 23°–35°API and 40–46° API). Potential petroleum (gas) generative intervals occur at surface and in the shallow subsurface in deltaic mudstones (Tanglefoot formation) and fluvial mudstones (Tantalus Formation). The lateral extent of these intervals is unknown due to poor outcrop exposure and limited shallow drilling. Both the Tanglefoot and Tantalus formations are interpreted as potential source rocks and possibly effective source rocks. The most prospective areas for petroleum exploration are Five Finger Rapids, Division Mountain and Tantalus Butte and in the northern portion of Whitehorse trough.

The apparatus of an Early Triassic conodont Neostrachanognathus tahoensisKoike, 1998 from Oritate, Kumamoto Prefecture, Japan, and a species of Neostrachanognathus from Oman were reconstructed. On the basis of five natural assemblages from the Oritate area, the three-dimensional apparatus model of N. tahoensis is interpreted as bilaterally symmetrical and composed of 14 elements consisting of pairs of P1, P2, P3, S1, S2, S3, and S4 elements. The P1 and P2 elements are coniform elements, the P3 elements are digyrate forms, and the S elements are bipennate ramiforms. The S elements are arranged rostrally in the apparatus and the pairs of the P1, P2, and P3 elements are subvertically arranged caudally and ventrally to the S array. One of the natural assemblages was formed by rostrocaudal collapse of the apparatus on the sea floor, whereas the other assemblages indicate that conodont animals came to rest nearly parallel with the substrate prior to burial. A collection of isolated elements from Jabal Safra, Oman, includes a second species of Neostrachanognathus with a comparable apparatus.

Chaohu is located in a deep part of carbonate ramp on the Lower Yangtze Block, which belonged to the low-latitude eastern Tethyan archipelago during the Early Triassic. Fossils were very rich in the Lower Triassic of Chaohu. Bivalves, ammonoids, conodonts were very common throughout the Lower Triassic, while fish fossils were generally rich in some beds of the upper part. It is one of the most typical sections for the Early Triassic chronostratigraphy in the world. Although various fossils had been studied in the 1980s and 1990s, recent studies based upon new and more detailed collections from the Lower Triassic of Chaohu showed that the conodont zonation needs revision. We collected Lower Triassic conodont fossils from continuous sections of the West Pingdingshan, North Pingdingshan and South Majiashan, Chaohu, Anhui Province, and updated zonations were made for each section. Eight conodont zones have been distinguished. They are, in ascending order, Hindeodus typicalis zone, Neogondolella krystyni zone, Neospathodus kummeli zone, Neospathodus dieneri zone, Neospathodus waageni zone, Neospathodus pingdingshanensis zone, Neospathodus homeri zone, and Neospathodus anhuinensis zone. The first occurrence of Neospathodus waageni eowaageni of the N. w. eowaageni subzone (i.e. the base of the N. waageni zone) is suggested as the marker to define the Induan–Olenekian boundary.

Conodont faunas are described from Triassic sections of Svalbard, and their occurrences are locally correlated with established ammonoid zones. With a synthesis of previous conodont-based publications, the current work presents a taxonomically up-to-date compilation of conodont data for the Triassic of Svalbard that is used to construct a conodont-based biochronology, indexed to the current lithostratigraphic nomenclature. Twenty-eight taxa spanning the earliest Griesbachian to the earliest Carnian are presented in a range chart. The examined conodont faunas are correlated with well-established conodont zonations of the Canadian Arctic, and in turn also form the basis for regional correlations.

The Chongzuo-Pingguo platform is a vast isolated platform, 180 km across, in the southern part of the Nanpanjiang basin. The end-Permian extinction is recorded in conformable sections in the northern part of the platform (Pingguo area). Upper Permian skeletal packstone contains diverse open-marine fossils including Nankinella and Sphaerulina. It is overlain by a 4.6 m thick horizon of calcimicrobial framestone constructed by globular calcified microbial framework similar to Renalcis. The PTB event horizon is interpreted to occur at the top of the packstone, coincident with the abrupt change to calcimicrobial framestone lacking Permian macrofossils. The transition from Hindeodus latidentatus to H. parvus occurs 1 m above the base of the calcimicrobial framestone, marking the conformable biostratigraphic boundary. During the Early Triassic the platform developed as a low-relief bank rimmed with oolite shoals but was bordered by a high-relief, fault-controlled escarpment along its southern margin. Platform interior facies of the Majiaoling and Beisi formations are 900 m thick and consist of thin-bedded lime mudstone, oolite, and dolostone with restricted marine biota in four shallowing-upward packages that define depositional sequences. In the Chongzuo area the platform was terminated at the end of the Early Triassic by burial with up to 1600 m of felsic pyroclastic volcanics and lava flows. Transgression and shallow-marine carbonate sedimentation resumed early in the Middle Triassic followed by drowning in the Bithynian as indicated by a shift to deep-marine carbonate and clastic deposition. In the Pingguo area volcanic deposits are much thinner and only briefly interrupted carbonate accumulation. Here the platform interior drowned during a major back step early in the Middle Triassic (Anisian, Bithynian). Smaller pinnacle platforms of the Guohua Fm., up to 1700 m thick, continued to accumulate above the Early Triassic platform margin and were eventually drowned by the Late Pelsonian. In the Anisian, the pinnacle platforms shifted to sharply defined, reef-rimmed margins with Tubiphytes reefs. The shift coincides with accelerated metazoan biotic recovery in the Anisian. However, the reefs lack metazoan frameworks and are composed almost entirely of Tubiphytes reinforced by large volumes of marine cement. These observations indicate that controls beyond the recovery of framework-building metazoans governed the re-establishment platform-margin reefs in the Middle Triassic.

The Early Triassic paleogeographical setting of the Chaohu section in China was in a deep part of the Yangtze platform and this has resulted in a rather complete Lower Triassic sequence with rich ammonoid and conodont successions. Three Lower Triassic sections, West Pingdingshan, North Pingdingshan and South Majiashan, have been sampled in detail for a systematic conodont study. Eight conodont zones are recognized; in ascending order these are the zones of Hindeodus typicalis , Neogondolella krystyni , Neospathodus kummeli , Neospathodus dieneri , Neospathodus waageni , Neospathodus pingdingshanensis , Neospathodus homeri , and Neospathodus anhuinensis. These are correlated with the sequences in North America and other areas of the world. The succession provides a good basis for the definition of the global stratotype of the Induan–Olenekian boundary (GSSP), which has been proposed at the base of the Neospathodus waageni Zone in West Pingdingshan. Seven new species are introduced: Neospathodus chaohuensis , N. chii , N. concavus , N. eotriangularis , N. pingdingshanensis , N. posterolongatus , N. tongi , a new subspecies N. waageni eowaageni , and three morphotypes of N. dieneri .

A study of latest Permian and Early Triassic multielement conodonts identifies eight steps in their evolutionary history during an interval when Earth's biosphere was highly stressed. These steps are: 1) gradual decline of families and genera through the Changhsingian (up to the late Griesbachian); 2) conodont biofacies change and extinction of Tethyan endemic species close to the Permian–Triassic Boundary (PTB); 3) faunal turnover with extinction and origination in the late Griesbachian; 4) initial radiation in gondolellids and diversification in apparatuses during the Dienerian; 5) explosive radiation in the early–middle Smithian; 6) major extinction in the late Smithian; 7) major radiation early in the Spathian; 8) gradual turnover and decline in the late Spathian through early Anisian. Conodontophorids were reduced from five families at the beginning of the Changhsingian to three by the PTB, and to two late in the Griesbachian. From the Changhsingian to the late Griesbachian, there was a single multielement apparatus represented in the Gondolellidae, whereas by the Olenekian there were at least twelve. Given absolute age constraints, the conodont recovery in the aftermath of the PTB was extraordinary. Conodont evolution during the Dienerian remains obscure but was very significant in terms of changes in multielement apparatuses. In spite of Induan extinctions, generic diversity generally increased from the PTB up to the late Smithian. In terms of species, genera, and multielement apparatuses, the acme of Triassic conodonts was in the middle Smithian, and the biggest extinction was in the late Smithian. After this extinction, generic and apparatus diversity quickly returned to high levels, marking a significant Spathian recovery. Gradual decline characterized the late Spathian and persisted into the early Anisian. A synthetic summary of the temporal distribution and proposed relationships amongst all known Lower Triassic conodonts provide an improved foundation for biostratigraphic and biochronologic studies. Extinction and radiation trends correlate well with sea-level changes and sequence boundaries: faunal turnovers correspond to lowstands in the late Griesbachian, late Smithian, and late Spathian, and radiations correspond to transgressions in the early Griesbachian, early Smithian, and early Spathian. The trends also correlate with perturbations in the carbon cycle, with Lower Triassic δ13C minima corresponding to extinction and faunal turnover, and positive values generally occurring during radiations. However, Middle Triassic recovery of marine benthos follows a positive maxima and an overall decline in conodont diversity. New taxa Borinella chowadensis, B. megacuspa, Neogondolella griesbachensis, and N. mongeri are described.

Palaeomagnetic and biostratigraphic data were obtained for the latest Ladinian and most of the Carnian (Botneheia Formation to basal Kapp Toscana Group), from two sections in central Spitsbergen (Svalbard archipelago). Thermal and alternating field (AF) demagnetization reveals a magnetization of both normal and reversed polarities. The mean directions pass reversal and fold tests and are similar to other European Late Triassic palaeopoles. One of the sections displays 15° of vertical-axis, clockwise, tectonic rotation on a decollement in the underlying Botneheia Formation. The magnetostratigraphy is dominated by normal polarity in the uppermost Botneheia Formation and into the Tschermakfjellet and basal De Geerdalen formations. A substantial hiatus characterizes the Ladinian–Carnian boundary in central Spitsbergen, so reverse magnetozones, identified in Tethyan sections near this boundary, are absent. Magnetostratigraphic correlation, along with palynostratigraphic constraints, indicates that most of the De Geerdalen Formation is Lower Carnian. The magnetostratigraphy and palynology indicates that the Isfjorden Member (upper unit of the De Geerdalen Formation) is probably mid-Carnian in age. Change in the lithological architecture in the Isfjorden Member, compared with the underlying parts of the De Geerdalen Fm, suggests a hiatus near the base of the member, which may represent a mid-Carnian unconformity, not previously recognized on Spitsbergen.

The Lower Devonian to Upper Permian Stikine Assemblage is well exposed in northwestern British Columbia, near the west-central margin of the Stikine terrane. The stratigraphic base of the assemblage is not exposed and the Upper Triassic Stuhini Group disconformably overlies the assemblage locally. The assemblage consists mainly of various types of volcanic rocks, and there is a large, polyphase, Devono-Mississippian sub-volcanic plutonic complex. The assemblage includes a distinctive, but laterally discontinuous mid-Carboniferous limestone named the Arctic Lake Formation. Facies are mainly locally re-worked, well-bedded skeletal wackestone, but whole fossil floatstone and intraformational olistostromal deposits are present. Stratigraphic thickness varies from 32 to 80 metres. Stratigraphic contacts with bounding Lower and Upper Carboniferous successions are conformable and intergradational, but paraconformities may also be present. The formation records weak development of disjointed carbonate ramps on volcanic highlands. Neritic faunal assemblages have warm water, open marine affinity. The formation spans the Serpukhovian-Bashkirian boundary and encompasses microfacies assigned to Global Foraminiferal zones 17, 18 and 20. Integrated foraminiferal-coralconodont biostratigraphy and uranium-lead geochronology support a circa 350 Ma age for the Tournaisian-Visean boundary, and a circa 320 Ma age for the Serpukhovian-Bashkirian (Mississippian-Pennsylvanian) boundary.

The Nanpanjiang Basin of south China contains four exceptionally well-exposed, isolated Triassic carbonate platforms. Detailed mapping of two-dimensional transects and description of stratigraphic sections allow the reconstruction of facies architecture, sequence stratigraphy, and evolution of the platforms. Biostratigraphy, magnetic-susceptibility profiles, and volcanic-ash horizons allow chronostratigraphic correlation and, thus, a basinwide evaluation of mechanisms controlling platform evolution. A comparison of platform architecture demonstrates that southerly platforms have substantially greater thickness, backstepping geometry, pinnacle development, and earlier drowning that resulted from greater tectonic subsidence proximal to a probable convergent margin along the southern perimeter of the basin. Felsic volcanics thicken southward and contributed to the termination of the southernmost platform, indicating the development of a volcanic arc along the southern margin of the South China tectonic block. The northernmost isolated platform had greater longevity and lesser accumulation and lacks backstepping and pinnacle phases of development. Basin-margin intertonguing relationships, or lack thereof, demonstrate that earlier siliciclastic influx into the basin to the south and concurrent starved-basin conditions to the north impacted the evolution of platform-margin geometries. Comparative analysis of platform evolution shows that the timing and rates of tectonic subsidence controlled the timing of platform termination by drowning, backstep geometries, pinnacle development, and overall platform thickness. The timing of siliciclastic basin fill dictated differences in platform-margin geometries such as slope angle, relief above basin floor, and the presence or absence of basinward platform progradation. Despite the dramatic differences in platform architecture, eustatic sea level fluctuations imparted a basinwide sequence-stratigraphic signal.

Processes and causes of biotic and environmental change at the Triassic–Jurassic transition remain controversial, partly because of a scarcity of Triassic–Jurassic boundary sections studied in detail. Continuous marine strata spanning the boundary are exposed at Csővar, Hungary, where new integrated stratigraphic data were obtained from multidisciplinary investigations to help reconstruct the end-Triassic and Early Jurassic events. Boundary strata are predominantly slope to basinal carbonates deposited in a periplatform basin. The position of the system boundary is constrained by radiolarian, foraminiferan, conodont and ammonoid biostratigraphy. Pronounced radiolarian turnover is observed between assemblages assigned to the Late Rhaetian Globolaxtorum tozeri zone and the Early Hettangian Canoptum merum zone. Benthic foraminifera suffered lesser extinction. Successive conodont faunas of the latest Rhaetian Misikella posthersteini and Misikella ultima zones record a marked drop in diversity and abundance but sporadic survivors persist into the earliest Hettangian. The extinction is also recorded in a reduction of biogenic components in carbonates. Decline of benthic and planktic biota is followed by a negative δ13Ccarb excursion of up to − 6‰ that is composed of short-term fluctuations revealed by dense sampling. Carbon and oxygen isotope ratios are positively correlated in the lower part of the section and appear to reflect primary variations. Drivers of the stable isotope trends are interpreted as warming in excess of + 10 °C and concomitant episodic, short-term perturbations of the global carbon cycle, possibly due to methane release from gas–hydrate dissociation induced by rapid climatic events. The main biotic and isotopic events occurred within a single sedimentary cycle but sea-level does not appear to have exerted a critical influence on these changes. The Triassic–Jurassic boundary crisis appears a short but not instantaneous event.

Bioclastic accumulations composed of crinoids, brachiopods, molluscs, spongiomorphs and scleractinian corals occur within Upper Triassic strata of the lower Baldonnel Formation at Pardonet Hill in northeastern British Columbia Canada. These small buildups (∼100 to 500 m3) have planar bases and broadly convex tops. These mounds are interpreted as small patch reefs composed of packstone, bioclastic floatstone/rudstone and carbonate breccia intercalated with mixed siliciclastic carbonate sediments deposited in a shallow subtidal setting (i.e. above fairweather wave base). Amalgamated hummocky cross-stratified to current ripple-laminated, quartz-dominated sandstone beds and numerous sharp-based, normally graded bioclastic (commonly encrinitic) packstone/grainstone — quartz–sandstone couplets characterize inter-reef lithologies. Conodont biostratigraphy indicates that the Pardonet Hill patch reefs occur within strata dated as earliest Upper Carnian (lower nodosus zone). The Pardonet Hill patch reefs originated and developed during an interval of regional sea level lowstand. Strata within which these patch reefs occur represent the westernmost migration of the Triassic shoreline in western Canada. Disappearance of coral reefs in the study area may have been affected by rapid marine transgression and failure of reef faunas to recolonize the new shore zone further to the east. The Pardonet Hill locality occurred on the western margin of the North American craton during the Triassic. Prior to their discovery reef-like structures dominated by corals in the western Panthalassa were limited to allochthonous terranes (now part of the Cordillera). The Pardonet Hill patch reefs occur at approximately 30° Triassic paleolatitude. In modern settings, this is at the extreme latitudinal margin of subtropical zooxanthellate reef development. The presence of benthic faunas characteristic of low-paleolatitude settings on the northwestern coast of Pangea has significant implications in paleotectonic and paleoenvironmental reconstructions.

We report a new ichthyopterygian assemblage from Lower Triassic horizons of the Prida Formation at Fossil Hill in central Nevada. Although fragmentary, the specimens collected so far document a diverse fauna. One partial jaw exhibits isodont dentition with blunt tipped, mesiodistally compressed crowns and striated enamel. These features are shared with the Early Triassic genusUtatsusaurusknown from coeval deposits in Japan and British Columbia. An additional specimen exhibits a different dentition characterized by relatively small, rounded posterior teeth resembling other Early Triassic ichthyopterygians, particularlyGrippia.This Nevada assemblage marks a southward latitudinal extension for Early Triassic ichthyopterygians along the eastern margin of Panthalassa and indicates repeated trans-hemispheric dispersal events in Early Triassic ichthyopterygians.

High-resolution carbon isotope measurements of multiple stratigraphic sections in south China demonstrate that the pronounced carbon isotopic excursion at the Permian-Triassic boundary was not an isolated event but the first in a series of large fluctuations that continued throughout the Early Triassic before ending abruptly early in the Middle Triassic. The unusual behavior of the carbon cycle coincides with the delayed recovery from end-Permian extinction recorded by fossils, suggesting a direct relationship between Earth system function and biological rediversification in the aftermath of Earth's most devastating mass extinction.

A mixed conodont fauna-bearing limestone breccia, informally designated as Necoslie breccia, crops out as an internal sediment hosted by the Lower Moscovian limestone unit of the Pope limestone succession (Bashkirian to Asselian) of Cache Creek Complex in central British Columbia, reconstructed as a mid-oceanic buildup upon a seamount, or an oceanic plateau. Necoslie breccia consists predominantly of limestone fragments derived from the host rocks, with subordinate isolated skeletal debris, all embedded in a matrix of fine-grained clastic carbonates. The mixed conodont fauna yields the youngest element indicative of Carnian. Our microscopic examination and conodont paleontological data show that Necoslie breccia is better defined as a neptunian dyke formed by infilling sedimentation of carbonates in a fracturing-generated submarine cavity, rather than a karstic cave-fill deposit. We postulate that infilling sedimentation took place immediately after the formation of the cavity, most likely in a transgression period during Carnian time.

The Olenekian Stage of the Lower Triassic is named from the Boreal Realm, but the stage has never been properly defined, nor has it been applied in the low-latitude Tethyan Realm, with exception of North Caucasus and Mangyshlak. This paper proposes a stratotype for the In-duan-Olenekian boundary in the low-latitude Tethyan Realm. South China is one of the main regions in the Tethyan Realm with well-developed Lower Triassic sequences and abundant fossils. According to the basic stratigraphic records and various accumulated data, we believe that the West Pingdingshan Section in Chaohu, Anhui Province is one of the best sequences to define the Induan-Olenekian boundary. The first appearance datum (FAD) of conodont Neospathodus waageni is the preferred index to define the boundary. This datum lies 26 cm below the FAD of the ammonoids Flemingites and Euflemingites, and is located slightly prior to the top of the second Triassic normal magnetozone, and the peak of the first Triassic positive excursion of carbon isotope σ13C.

A new Lower to Middle Devonian basinal unit of the Road River Group, herein formally named the Deserters Formation, contains argillaceous, crinoidal limestone and black shale deposited in a linear sub-basin of the Ospika Embayment, southern Kechika Trough. The abrupt lateral facies changes in the region, facies thickness, and occurrence of volcanics indicate a period of extensional tectonism. A total of 53 (4–5 kg each) samples from the Deserters Formation yielded 7766 conodont elements assigned to 14 genera representing 33 species. The formation ranges from the Lochkovian (eleanorae Zone, or lower part of the delta Zone of the Cordilleran Region) to Eifelian (australis Zone). The temporal constraints established by conodont biostratigraphy allow correlation to the Grizzly Bear Formation, a regionally restricted Lower to Middle Devonian unit in the Selwyn Basin to the north.

Elasmobranchs are reported for the first time from Lower Triassic deposits in Oman. The well-preserved remains consist of isolated teeth, dermal denticles and fin spines, recovered from conodont residues. The low-palaeolatitude sections consist of Lopingian–Olenekian shallow and pelagic carbonates in exotics, olistoliths and breccia blocks that have been redeposited in younger allochthonous strata of the Hawasina Basin throughout the Oman Mountains at Jabal Safra (olistoliths within the Jurassic Guwayza Formation, Olenekian), as well as at Wadi Alwa (exotic Alwa Formation, Lopingian–Olenekian) and Wadi Wasit Block (slope breccia in the Al Jil Formation, Induan), both of which occur in the Ba'id region. The recovered fauna contains a small number of pre-existing genera, but is mainly composed of new hybodont and neoselachian taxa. They are identified as: Omanoselache halli Koot & Cuny sp. nov., cf. Omanoselache sp., Safrodus tozeri Koot & Cuny gen. et sp. nov. and Polyfaciodus pandus Koot & Cuny gen. et sp. nov., based on the majority of the recovered dental remains. Spine fragments are identified as cf. Amelacanthus sp. This fauna represents the second published record of neoselachian teeth from the Induan and the most extensive record from the Lower Triassic in terms of abundance and diversity. The fauna is dominated by Neoselachii, whereas other Early Triassic faunas are hybodont-dominated, and histological study of the neoselachian enameloid significantly adds to our knowledge of the early stages of their evolution. All described taxa are new to the Oman fossil record and that of western Neotethys, apart from Omanoselache and Amelacanthus, which have been recognized from Wordian deposits, and Omanoselache is the second genus from Oman known to have survived the late Permian mass extinction. The level of faunal diversity recognized here is comparable to other Early Triassic faunas but is much reduced compared to the Wordian pre-extinctions fauna.http://zoobank.org/urn:lsid:zoobank.org:pub:E82E8BC2-1743-4883-B27B-3564DAAF2DF1

Three classic sections of Middle and Late Triassic fossiliferous limestones cropping out around Williston Lake in British Columbia, Canada, were sampled for paleomagnetic study. The objective was to test the suitability of these units for detailed magnetobiostratigraphic study with the aim of improving the reference Triassic geomagnetic polarity time scale. The Williston Lake characteristic magnetizations differ, however, from any Triassic North America cratonic reference directions. A satisfactory agreement is found instead with Cretaceous - early Cenozoic North America cratonic reference directions. The exclusive occurrence of normal polarity suggests that remagnetization likely occurred during the Cretaceous long normal superchron. Remagnetizations may have been triggered by connate brines, which moved along aquifers of porous sandstones and carbonates in the early stages of Laramide folding. Resume : Trois sections fossiliferes classiques de calcaires (Trias moyen et tardif), affleurant autour du lac Williston en Colombie Britannique, ont ete echantillonnees pour une etude paleomagnetique. L'objectif etait de s'assurer de la pertinence de ces unites pour une etude magneto-bio-stratigraphique detaillee visant a ameliorer l'echelle referentielle de temps de la polarite geomagnetique au Trias. Les magnetisations caracteristiques du lac Williston different toutefois de toute direction cratonique referentielle au Trias en Amerique du Nord. Toutefois, une correlation satisfaisante est etablie avec les directions cratoniques referentielles du Cretace-Cenozoique precoce en Amerique du Nord. L'occurrence exclusive d'une polarite normale suggere qu'il y eut probablement une remagnetisation au cours du long superchron normal du Cretace. Les remagnetisations peuvent avoir ete declenchees par des saumures connees qui se sont deplacees le long d'aquiferes de gres et de carbonates poreux dans les premieres phases du plissement Laramide.

Exceptionally well preserved Lower Triassic conodonts from Oman include an array ofNeospathodusspecies, many of which are new. Those from the upper Lower Triassic, or Spathian, are described in conjunction with a restudy of conodont type material from Chios, Greece, and an assessment of contemporary collections from Pakistan and western North America. The taxonomic scope of three key species from Chios,Neospathodus homeri, N. triangularis, andN. gondolelloides, is revised. Seven new species are described from Oman:N. abruptus, N. brevissimus, N. brochus, N. crassatus, N. curtatus, N. pusillus, andN. symmetricus;and one new species,N. clinatus, is described from Pakistan. The alliedIcriospathodus collinsoniis also described from Oman. The occurrence and range ofNeospathodusspecies are presented in the context of the ammonoid succession in the Spathian of North America. BothN. homeriandN. triangularis, as revised, have shorter ranges and are more age diagnostic than previously thought.Neospathodus gondolelloidesis a distinct taxon, and not synonymous withChiosella timorensis.Five informal faunal divisions are identified based onNeospathodusand allied species. In ascending stratigraphic order, these are typified byIcriospathodus collinsoni, Neospathodus homeri, N. triangularis, N. symmetricus, andN. gondolelloides.Oman collections represent three of these faunas, which occur also in theColumbitesthroughProhungarites/Subcolumbitesammonoid beds of western U.S.A.

The 34-million-year (My) interval of the Late Triassic is marked by the formation of several large impact structures on Earth. Late Triassic impact events have been considered a factor in biotic extinction events in the Late Triassic (e.g., end-Triassic extinction event), but this scenario remains controversial because of a lack of stratigraphic records of ejecta deposits. Here, we report evidence for an impact event (platinum group elements anomaly with nickel-rich magnetite and microspherules) from the middle Norian (Upper Triassic) deep-sea sediment in Japan. This includes anomalously high abundances of iridium, up to 41.5 parts per billion (ppb), in the ejecta deposit, which suggests that the iridium-enriched ejecta layers of the Late Triassic may be found on a global scale. The ejecta deposit is constrained by microfossils that suggest correlation with the 215.5-Mya, 100-km-wide Manicouagan impact crater in Canada. Our analysis of radiolarians shows no evidence of a mass extinction event across the impact event horizon, and no contemporaneous faunal turnover is seen in other marine planktons. However, such an event has been reported among marine faunas and terrestrial tetrapods and floras in North America. We, therefore, suggest that the Manicouagan impact triggered the extinction of terrestrial and marine organisms near the impact site but not within the pelagic marine realm.

In the Queen Charlotte Islands, on the Pacific shore of Birtish Columbia, Canada, Triassic-Jurassic boundary beds are present in several well-exposed sections of the Sandilands Formation. Triassic and Jurassic ammonoids, Triassic conodonts and Triassic and Jurassic radiolarians indicate the position of the boundary to within a few metres. The section may be essentially continuous across the boundary. The evidence suggests more or less simultaneous extinction of ammonoid, conodont and radiolarian faunas at the T-J boundary.

The western flank of the Coast Mountains batholith between Cape Fanshaw and Taku Inlet is underlain primarily by Jura-Cretaceous strata of the Gravina belt; pre-Permian(?), Permian, and Triassic strata of the Taku terrane; and mid-Proterozoic(?) to upper Paleozoic rocks of continental margin affinity. The continental margin rocks include mid-Proterozoic(?) to lower Paleozoic(?) quartzite and marble of the Tracy Arm assemblage; mid-Paleozoic metavolcanic and subordinate metasedimentary rocks of the Endicott Arm assemblage; and upper Paleozoic quartz-rich metaturbidites and metaconglomerate of the Port Houghton assemblage. We suggest that these three assemblages are correlative with components of the Yukon-Tanana terrane, which underlies a large region of Yukon and eastern Alaska. Rocks of the Gravina belt, Taku terrane, and Yukon-Tanana terrane are juxtaposed along west-vergent thrust faults of mid-Cretaceous age and are internally deformed and disrupted along latest Cretaceous to early Eocene dip-slip and possibly strike-slip shear zones. These rocks and structures, together with mid-Cretaceous to Eocene plutons of the Coast Mountains batholith, separate rocks of the Alexander-Wrangellia terrane to the west from rocks of the Stikine terrane to the east. Mid-Cretaceous thrust faults in the area belong to a system of thrusts that form the inboard margin of the Alexander-Wrangellia terrane from central Alaska to northwestern Washington. The continental margin rocks in the northern Coast Mountains may be part of the in situ North American margin that has been overthrust by the Stikine and adjacent terranes. Alternatively, these rocks may have (1) rifted from and then returned to the North American margin, (2) moved >800 km along left-lateral or right-lateral faults from elsewhere along the North American margin, or (3) originated near a continent other than North America.

The Stikine assemblage, the "basement" of Stikinia, extends 500 km along the western flank of the Intermontane Belt, east of younger Coast Belt plutons. Four different stratigraphic successions are characteristic of Lower to Middle Devonian, Carboniferous and Permian rocks in the Stikine and Iskut rivers area. West of Forrest Kerr Creek are penetratively deformed Lower to Middle Devonian island-arc volcaniclastic rocks, coralline limestone, and felsic tuff. Fringing carbonate buildups in an arc setting are best illustrated in the sequence at Round Lake where Lower Carboniferous mafic-dominated, bimodal submarine volcanic rocks grade upward into two distinctive coarse echinoderm limestone units and medial siliceous siltstone and limestone conglomerate. Conodont colour alteration indices for Lower Carboniferous rocks near Newmont Lake indicate an anomalously low-temperature thermal history. Upper Carboniferous–Permian polymictic volcanic conglomerate and Lower Permian limestone overlie these strata there. The Scud River sequence is distinguished by subgreenschist- to greenschist-grade Carboniferous(?) volcanic and sedimentary rocks overlain by a structurally thickened package (greater than 1000 m) of Lower Permian limestone. Local calcalkaline pyroclastic rocks interfinger with limestone near the top of the Scud River sequence. Basinal, shelf, and shallow-water carbonate facies developed in the Early Permian, giving way to calcalkaline volcanism in Late Permian followed by deposition of deep-water chert and argillite.The tectonic setting during the Devonian and Carboniferous is comparable with modern Pacific volcanic arcs and atolls, but there is no modern analogue for the shelf-carbonate accumulation during the Early Permian which characterizes the Stikine assemblage and permits Cordilleran-scale correlations. Permian fusulinid and coral species have very close affinity to those of the McCloud Limestone of the eastern Klamath Mountains, California. Other geologic events common to both Stikinia and the Eastern Klamath terrane are Devonian limestone breccia deposition, Lower Permian limestone accumulation with McCloud faunal affinity, Carboniferous and Permian calcalkaline volcanism, and Upper Permian tuffaceous limestone. Stratigraphic differences include the absence of quartz detritus in Devonian strata and lack of thick Upper Permian volcanic rocks in the Stikine River area.

Conodont faunas are described from the type sections of Lower Triassic stages in the Canadian Arctic. The collections come largely from ammonoid-bearing strata of the Strigatus (upper Griesbachian), Candidus (lower Dienerian), Romunduri and Tardus (lower and upper Smithian), and Subrobustus (upper Spathian) zones. These demonstrate that diverse late Griesbachian conodont faunas included the first species of Borinella, Neospathodus and Scythogondolella, accompanied by several species of Neogondolella. Dienerian faunas are dominated by Neospathodus, but explosive radiation led to several Smithian Scythogondolella species and diverse cosmopolitan “neospathodid” species of Conservatella, Discretella and Neospathodus. Smithian Paullella (nomen novum) and Wapitiodus are recorded here for the first time in the Arctic collections, and emphasize the correlation with successions in the Western Canada Sedimentary Basin (WCSB) and in the western USA. Conodonts from the Romunduri Zone differ in the three regions: Conservatella, Discretella and Paullella are rare in the Arctic, are more common in WCSB and are most common in the USA; Scythogondolella species are common in the Arctic, less so in WCSB and are virtually absent in the USA. Conodonts from the Tardus Zone, both in the Arctic and elsewhere, contain cosmopolitan Borinella buurensis, Neospathodus waageni, Scythogondolella mosheri and Scythogondolella milleri. Spathian conodont faunas from the Subrobustus Zone are dominated by Neogondolella species, which also occur in the WCSB associated with Triassospathodus. These two genera have an inverse relationship: Triassospathodus dominates the USA successions, and is virtually absent in the Arctic. Scythogondolella ellesmerensis sp. nov. and Scythogondolella lachrymiformis sp. nov. are described.