Carnian Pluvial Episode Research Articles

Floral response to the Late Triassic Carnian Pluvial Episode

The Late Triassic Carnian Pluvial Episode (CPE; ca. 234–232 Ma) was characterized by dramatic global temperature and humidity increases, which in many terrestrial settings was accompanied by changes from arid to humid vegetation types. This study reviews current evidence of terrestrial floral composition and distribution during the CPE and analyzes spatial and temporal variation with relation to potential environmental driving mechanisms. Available evidence suggests the CPE was a globally significant event that triggered significant increases in the abundance of ferns and hygrophytes in terrestrial floras and freshwater algae in fluvial and lacustrine settings. These changes ended a long interval of relatively arid terrestrial climatic conditions since the Early Triassic and are linked temporally with eruptions of the oceanic plateau Wrangellia Large Igneous Province (LIP). The massive release of greenhouse gasses including isotopically light CO2 during 3–4 distinct pulses of Wrangellia volcanism appears to have been the main driver of CPE climate change. Each pulse enhanced global atmospheric circulation and the hydrological cycle and resulted in changes from arid to humid conditions that affected floral abundance and composition. Higher terrestrial primary productivity in humid phases facilitated increased burial of terrestrial organic carbon and led to the recommencement of peat accumulation, ending the coal gap that had persisted since the Earliest Triassic times. Enhanced movement of carbon from the atmosphere through the biosphere into the geosphere may have counteracted the warming effects of Wrangellia volcanic greenhouse gas emissions and ultimately led to the return of a steady climate state that terminated the warm and humid conditions of the CPE.

Intensified lacustrine turbidite deposition as a response to the Carnian Pluvial Episode: Insights from the Triassic Ordos Basin in North China Plate

The Carnian Pluvial Episode (CPE) is a period during which the rainfall was extremely intense and greatly influenced the deposition in different sedimentary environments globally. However, the relationship between the CPE and turbidite deposition remains poorly known. Here we investigate a giant lacustrine turbidite system of the Triassic Ordos Basin in North China Plate, to determine how the CPE influenced turbidite deposition, by integrating geochronology, organic carbon isotope, major and trace elements, clay minerals and turbidite sedimentology. Results show that the lacustrine turbidite deposition in the Ordos Basin was strongly associated with the CPE. Although there is a temporal lag, the intensified turbidite deposition is considered as a response to the three humid periods during the CPE. Compared with marine environments, continental depositional settings tend to be more sensitive to the humid climate changes, and can record more detailed and long-term carbon fluctuations. This study highlights the potential for turbidite deposition affected by extremely humid events, and provides new insights into the prediction of deep-water turbidite systems. Furthermore, it enriches the theory of the CPE in terrestrial environments.

Unique dentition of rhynchosaurs and their two‐phase success as herbivores in the Triassic

AbstractRhynchosaurs were key herbivores over much of the world in the Middle and Late Triassic, often dominating their faunas ecologically, and much of their success may relate to their dentition. They show the unique ankylothecodont mode of tooth implantation, with deep roots embedded in the bone of the jaw and low crowns that were rapidly worn down in use. During growth, the main area of oral food processing, located in the middle and posterior portions of the occlusal surfaces of the jaws, moved posteriorly relative to the anterior tips of the jaws, which curved up. As the maxilla and dentary grew by addition of new bone posteriorly, the dental lamina fed in new teeth at the back of the tooth rows. CT scanning of the holotype skull of Bentonyx sidensis from the Middle Triassic of England reveals previously concealed details of the dentition. Together with new dentary material from the same location, this has enabled us to examine the tooth replacement process and elucidate ontogenetic changes in dentition and jaw morphology as the animals aged. There were major changes in rhynchosaur anatomy and function through their evolutionary history, with the early forms of the Middle Triassic dying out before or during the Carnian Pluvial Episode (233–232 Ma), and the subclade Hyperodapedontinae, with broad skulls and adaptations to chop tough vegetation, subsequently diversifying worldwide in a successful ecological expansion until their global extinction 227–225 Ma.

Weathering and sea level control on siliciclastic deposition during the Carnian Pluvial Episode (Southern Alps, Italy)

Weathering and sea level control on siliciclastic deposition during the Carnian Pluvial Episode (Southern Alps, Italy)

‘A hard rain's a‐gonna fall’: torrential rain, flash floods and desert lakes in the Late Triassic Arden Sandstone of Central England

The Arden Sandstone Formation of central and western England is a thin but conspicuous arenaceous unit within the Late Triassic Mercia Mudstone Group. Sedimentological and palaeontological data point to lacustrine depositional conditions, in contrast to the red desert mudstones above and below which were deposited as continental dryland desert floodplains. The Arden Sandstone records deposits of the lake margins and may be the high stand lateral equivalent of the halite and gypsum deposits which formed in the lake centre. The Carnian age of the Arden Sandstone potentially links it to the Carnian Pluvial Episode, marking the coalescence, spread and freshening of the formerly saline desert lakes, and deposition of sandy, fluvial and lacustrine deposits, during the wetter climate that prevailed for at least a million years.

The first record of chigutisaurid amphibian from the Late Triassic Tiki Formation and the probable Carnian pluvial episode in central India.

A new, partially preserved skull of chigutisaurid amphibian (temnospondyli) has been reported for the first time from the Late Triassic Tiki Formation of India. Chigutisaurids are now known to occur in Australia's Early and Late Triassic, the Late Triassic in India, Argentina, and Brazil, the Jurassic of South Africa and Australia, and the Cretaceous of Australia. In India, the first appearance of chigutisaurids marks the Carnian-middle Carnian/Norian Boundary. This work also attempts to correlate, again for the first time, the advent of chigutisaurids and the occurrence of Carnian Pluvial Episodes (CPE) in the Late Triassic Maleri and Tiki Formation of Central India. The new specimen belongs to the genus Compsocerops prevalent in the Late Triassic Maleri Formation occurring 700 km south. However, the chigutisaurid specimen recovered from the Tiki Formation is a new species when compared to that of the Maleri Formation. It has the presence of an inward curved process of the quadratojugal as opposed to the straight downward trending process of the quadratojugal, the presence of vomerine foramen, shorter and wider interpterygoid vacuities, wider subtemporal vacuities, and the base of the interpterygoid vacuities at the same level with the base of the subtemporal vacuity. It proves that the Tiki Formation is coeval with the Lower Maleri Formation and a part of Upper Maleri.

Climax in Wrangellia LIP activity coincident with major Middle Carnian (Late Triassic) climate and biotic changes: Mercury isotope evidence from the Panthalassa pelagic domain

The Carnian Pluvial Episode (CPE, ∼233 Ma) was characterized by multiple negative carbon-isotope excursions, turnovers in marine and terrestrial biota, and a Tethys-wide humid climate accompanied by abundant terrigenous sediment and freshwater input into sedimentary basins. A general temporal coincidence between the CPE and the emplacement of the Wrangellia Large Igneous Province (Wrangellia LIP) has been well documented, however, it remains unclear whether fluctuations in the intensity of the LIP's activity could be linked to the biotic and climate changes at the CPE. We here present mercury (Hg) concentration and isotope ratio records from a pelagic deep-water succession (Section N-O, Inuyama, Japan) that encompasses the CPE interval. Data reveal concurrent peaks in the Hg concentrations and ratios of Hg to TOC and enrichment factors ThEF, AlEF, ZnEF, and NiEF implying that excess Hg loading in the sediments occurred, likely due to volcanic activity, prior to the CPE siliciclastic input. Furthermore, Δ199Hg values show a negative shift across the boundary between the Julian 1 and Julian 2, followed by a positive shift up to near-zero values at the Julian/Tuvalian transition. The near-zero Δ199Hg values at the Julian/Tuvalian boundary are associated with an increase in Hg and Cu loading, suggesting a peak of volcanogenic Hg and Cu input that may indicate a climax in the Wrangellia LIP activity. Most notably, the Julian/Tuvalian transition is where evidence of the most pronounced changes in carbonate platform evolution, biological turnover and climate change associated with the event has been highlighted. Our results therefore suggest that variations in the intensity of LIP volcanism may have played a major role in driving biotic and climate changes during the CPE. Our results provide a model for other mass extinction events associated with LIPs (e.g., the end-Permian) where low-intensity background volcanism was punctuated by high-intensity pulses, these latter being the real killers.

Vegetation changes and climate shift during the latest Ladinian to the early Carnian: Palynological evidence from the Yanchang Formation, Ordos Basin, China

The Middle–Late Triassic climates have attracted the attention of paleontological and geological scientists for the Carnian pluvial event in the early Late Triassic. The event is well-documented in the pelagic and epi-continental marine deposits of the Tethys, Gondwana, and Laurasia. However, inland terrestrial deposits are less frequently depicted, with high-resolution palynological biostratigraphy constraints. In this study, we report the palynological records from the YC8-1 and YC7-3 sub-members of the Yunmeng profile in the Ordos Basin, China, where the YC7-3 was dated at 236.0–234.1 Ma. Two palynological assemblages were recognized and named the Lundbladispora watangensis–Taeniaesporites combinatus assemblage and Lundbladispora communis–Discisporites granulus assemblage for the YC8-1 and YC7-3 sub-members, respectively. Their ages were determined to be the latest Ladinian and early Carnian, respectively, for their stratigraphic correlations with the global boundary stratotype section and point (GSSP) of the base of Carnian in Europe and additional co-occurring floras with condonts in the Upper Triassic of South China. The coexistence of Cyathidites minor (Couper, 1953), Dictyophyllidites harrisii (Couper, 1958), Apiculatisporis bulliensis (Helby ex De Jersey, 1972), Aratrisporites xiangxiensis (Li and Shang, 2011), Piceaepollenites omoriciformis (Bolkh.) (Xu and Zhang, 1984), Podocarpidites ornatus (Pocock, 1962), Discisporites granulus (Zhang, 1984), and Classopollis (Pflug, 1953) is equivalent to the Carnian palynostratigraphic criterion reported in the North China palynofloristic realm. Vegetational changes, especially those occurring at the boundary between Ladinian and Carnian, account for approximately 70% of ferns and over 30% of gymnosperms lost. These were discovered and attributed to the strong seasonal arid climate, indicated by the emergence of Cheirolepidiaceae and Pinuspollenites. We thus know that the climate during the latest Ladinian and early Carnian was “hot house” with seasonal aridity. In addition, three strong monsoonal pluvial pulses were signaled by the humidity index of lowland plants. The present study will enable a better understanding the Carnian pluvial event in the Late Triassic inland basin.

A giant phytosaur (Diapsida, Archosauria) from the Upper Triassic of India with new insights on phytosaur migration, endemism and extinction

AbstractA new Mystriosuchinae phytosaur,Colossosuchus techniensis, is described from the Upper Triassic Tiki Formation of India.Colossosuchusis diagnosed by multiple apomorphies, including a strongly downturned terminal rosette (c. 70°), closely spaced mediolateral band‐like ornamentation on dorsal surface of the nasal, dorsolaterally oriented supratemporal fenestra, ventrolaterally inclined postorbital–squamosal bars depressed below the skull table, dorsally convex parietal–squamosal bar that descends ventrolaterally below the skull roof, dome‐shaped skull in lateral view, prominent neural arch laminae and fossae, three sacral vertebrae, robust proximal end of the tibia, and fibula with high anteroposterior flaring of the distal end. The total body length of the largest individual recovered from the bonebed is estimated to be more than 8 m, suggesting thatColossosuchusis one of the largest phytosaurs known. Phylogenetic analysis nestsColossosuchusand other undescribed specimens from India within Mystriosuchinae. These form a distinct clade and represent the earliest record of endemism among Gondwanan phytosaurs. This clade is recovered as sister taxa to ((Volcanosuchus + Rutiodon) + Leptosuchomorpha), where the depressed supratemporal fenestra first appeared in the phytosaur lineage, a feature previously used to diagnose the derived leptosuchomorphs. Early‐diverging phytosaur diversification may have coincided with the final stages of the Carnian Pluvial Event with their possible migratory routes along the circum‐Tethyan coastline. The lineage continued to evolve mostly through endemic radiations and experienced an extinction event during early Norian, which marked the disappearance of most of the non‐leptosuchomorph taxa. This is attributed to post‐CPE aridification, although more study is required.

Organic matter accumulation of the Upper Triassic Ma'antang shales in the Longmenshan Foreland Basin (western Sichuan, China)

The Upper Triassic Ma'antang Formation is not only an important set of source rocks in the Sichuan Basin but may also be a successor for shale gas in China. In this study, the provenance, tectonic setting, chemical weathering, environment and productivity of the middle–late Carnian (Tuvalian) are reconstructed from petrological and geochemical data to determine the origin of the Ma'antang shales. The brachiopod-dominated fossil composition, type II-dominated organic matter, and fluctuating water salinity reflect that the shale formed in a marine environment influenced by terrestrial influx. TiO2 vs. Zr and La/Th vs. Hf diagrams, as well as the combination of major elements indicate that the Sichuan Basin was a collisional setting in the Tuvalian, and the provenance was felsic igneous source rocks. Redox-sensitive elements indicate dysoxic–anoxic conditions. Samples with Cd/Mo < 0.1 and Co*Mn > 0.4 show normal levels of Cd and relative enrichment of Mn and Co, which supports that the shale is more likely to be a product of anoxic preservation mode associated with the restricted basin. In contrast, the moderate productivity conditions reflected by Babio and P/Ti are also positive factors for organic matter accumulation. Based on the reconstruction of these environmental parameters, several driving factors that promote the formation of high TOC shales are explored. It is believed that the rapid tectonic subsidence in the early stage of foreland basin evolution (undercompensation period) created accommodation space for the shale, and the deep water also promoted anoxic bottom water, which facilitated the preservation of organic matter. The Carnian Pluvial Episode (CPE) increased global weathering and rainfall, allowing the oceans to receive more terrestrial nutrients, and freshwater influx caused stratification due to differences in salinity between the surface water and bottom water. Volcanic ash from the Wrangellia Large Igneous Province (W-LIP) and volcanic ash from local volcanoes were transported over long distances in the Late Triassic megamonsoons. Both were able to stimulate marine productivity, maintain and expand oceanic anoxia, and were beneficial for organic matter accumulation.

A Triassic crown squamate.

Mammals, birds, and squamates (lizards, snakes, and relatives) are key living vertebrates, and thus understanding their evolution underpins important questions in biodiversity science. Whereas the origins of mammals and birds are relatively well understood, the roots of squamates have been obscure. Here, we report a modern-type lizard from the Late Triassic of England [202 million years (Ma)], comprising a partial skeleton, skull, and mandibles. It displays at least 15 unique squamate traits and further shares unidentatan and anguimorph apomorphies. The new discovery fixes the origin of crown Squamata as much older than had been thought, and the revised dating shows substantial diversification of modern-type squamates following the Carnian Pluvial Episode, 232 Ma ago.

Terrestrial and marine organic matter evidence from a Cretaceous deep-sea chert of Japan: Implications for enhanced hydrological cycle during the Aptian OAE 1a

The early Aptian Oceanic Anoxic Event (OAE 1a; ca. 120 Ma) was accompanied by a massive eruption of the Ontong Java Plateau, doubling atmospheric pCO₂, and increasing sea surface temperature by 4–8 °C. In this study, we attempted a palynological analysis of the Hauterivian to Cenomanian deep–sea chert from the Goshikinohama site, and successfully obtained a variety of microremains, mainly represented by amorphous organic matter, aggregations of organic and inorganic particles, and cuticle fragments. One Hauterivian and many Aptian samples unexpectedly yielded terrestrial plant material, such as resins and wood fragments with tracheids, which represent the first record of terrestrial plant microremains from deep-sea pelagic chert. The occurrence of wood fragments within the negative and positive δ13C excursions during the OAE 1a can be correlated with an interval of increased atmospheric CO₂ level. We can also suggest that the occurrence of resins, mainly within the mudstone-rich chert intervals of the early Aptian negative δ13C peak and the middle-upper Aptian interval, are possibly related with periods with sea-level drops. Similar massive resin deposition events have been linked with intensified hydrological cycling during other abrupt climatic disruptions, such as the Carnian Pluvial Event, the Triassic−Jurassic boundary, and the Paleocene−Eocene Thermal Maximum. Therefore, an increase of terrestrial plant burial in deep–sea chert is likely linked with a massive plant discharge related with enhanced hydrological cycles, such as intensified storms and/or some sea–level change during the OAE 1a.

Eustatic sea-level fall and global fluctuations in carbonate production during the Carnian Pluvial Episode

In this paper, sea-level fluctuations during the Carnian Pluvial Episode (CPE) are investigated. A revision of published data from multiple successions worldwide indicates a sea-level drop that occurred in different geodynamic settings after the onset of the first of multiple carbon-isotope perturbations that characterize the CPE. New stable isotope data, zircon U-Pb geochronology, carbonate petrology, conodont and foraminifer biostratigraphy from the Carnian of the Sichuan Basin and comparison to the well-dated coeval successions of the Dolomites allow pinpointing with unprecedented precision this sea-level fall and determine that it occurred after the onset of the first, but prior to the third negative δ13C shift of the CPE. These lines of evidence indicate that such sea-level oscillation was eustatic. Facies analysis and sequence stratigraphy of units deposited during the ensuing sea-level rise in the Sichuan and Dolomites, further show that a Tethys-wide crisis of microbial carbonate production and drowning of carbonate platforms were followed by a recovery of marine calcification, widely testified by the deposition of oolitic bodies. Whereas a Tethys-wide recovery of microbial carbonate production is documented at the end of the Carnian, this increase in chemical calcification occurred earlier, at the beginning of the Tuvalian, and suggest that global transformations in carbonate systems coincident with the CPE were complex and share commonalities with other times in the geological record when a similar evolution was linked to ocean acidification.

An Exceptionally Preserved Terrestrial Record of LIP Effects on Plants in the Carnian (Upper Triassic) Amber-Bearing Section of the Dolomites, Italy

The Carnian Pluvial Episode (CPE) has been recognized as a time of plant radiations and originations, likely related to observed swift changes from xerophytic to more hygrophytic floras. This suggests that the increasing humidity causally resulting from LIP volcanism was the trigger for these changes in the terrestrial realm. Understanding the cause and effects of the CPE on the plant realm, requires study of well-preserved floras that are precisely aligned with the CPE. We therefore focus on the best age-constrained section within the CPE for the terrestrial to marginal marine environment to understand the floristic composition at the early CPE. This is found in the Dolomites, Italy, and is remarkable for the preservation of the oldest fossiliferous amber found in the rock record. An integrated study of palynomorphs and macro-remains related to the conifer families of the fossil resin bearing level brings together the floral components from this section. This observed mixture of different taxa of extinct and modern conifer families underlines firmly the effects of the LIP-induced CPE on the evolution and radiation of conifers.

A new exposure of the North Curry Sandstone Member (Dunscombe Mudstone Formation, Mercia Mudstone Group: Carnian, Triassic), near Taunton, Somerset (UK): The location of Charles Moore's vertebrate specimens resolved

There is renewed interest in a series of Carnian-aged sandstone units across the UK because they represent a unique event in the Late Triassic, the Carnian Pluvial Episode (CPE), from 233 to 232 Ma. The North Curry Sandstone Member of the Mercia Mudstone Group in Somerset is of particular importance because it yielded a rich fauna of shark, bony fish and amphibian remains in coarse-grained sandstones to Charles Moore in the 1860s. However, the exact location and age of his important collection had not been identified. Here, we demonstrate that the Moore collection comes from the North Curry Sandstone Member in a location in the village of Ruishton, just east of Taunton, where a new road cutting reveals both the bone-rich units and a complete succession through the CPE, a time of major climatic and biotic upheaval. The 16 m section comprises several sandstones interbedded with red-green mudstones, representing a terrestrial environment with lacustrine, evaporitic mud flat and fluvial deposits.

Increased Terrigenous Supply to the Pelagic Panthalassa Superocean Across the Carnian Pluvial Episode: A Possible Link With Extensive Aridification in the Pangean Interior

In the Late Triassic, a global environmental change called the Carnian Pluvial Episode (CPE) emerged, causing major biological turnover. The CPE has been recognized by siliciclastic input to sedimentary basins, multiple carbon isotope perturbations, and climate proxies for humidification. The CPE is considered to have been associated with increased atmospheric pCO2 from eruptions of large igneous provinces. However, the nature of this global environmental perturbation on the continents is still not well understood. Here we present a geochemical analysis of a pelagic deep-sea bedded chert sequence across the CPE in the Jurassic accretionary complex of Mino terrane, central Japan. Fluctuations in terrigenous material supply were reconstructed using Principal Component Analysis of major element compositions. The first principal component positively correlates with elements enriched in clay minerals such as Al2O3, whereas it negatively correlates with CaO, P2O5, and MnO, derived from apatite and manganese. A sudden increase in terrigenous supply was detected around the Julian/Tuvalian boundary, suggesting that CPE-related siliciclastic input also occurred in the abyssal plain environment. The terrigenous supply returned to the pre-CPE state in the Tuvalian. Since the terrigenous material supplied to the abyssal plain is thought to be derived from eolian dust blown from continental arid regions, the increasing terrigenous supply detected in the pelagic deep-sea chert succession may indicate extensive aridification. This result seems to conflict with the common view of the CPE as a humidification event. This contradiction possibly suggests that the extensive aridification occurred within the interior of the supercontinent Pangea, while hydrological circulation enhanced on the coastal region during the CPE.

Ichnodiversity and facies of Triassic red beds in the Irohalene area (Argana Basin, Western High Atlas, Morocco): implications for palaeoenvironment

ABSTRACT From Middle-Late Triassic continental deposits of the Timezgadiouine Formation (Argana Basin, Morocco), 17 lithofacies are identified, with alluvial fan, fluvial, floodplain and lacustrine associations. Invertebrate traces include Archaeonassa fossulata, Arenicolites isp., cf. Arenituba, Beaconites isp., cf. Camborygma, Cruziana problematica, Diplocraterion isp., Fuersichnus isp., Helminthoidichnites tenuis, Lockeia isp., Palaeophycus striatus, Palaeophycus tubularis, Planolites isp., Rusophycus carbonarius, Scoyenia gracilis, Skolithos isp., Spongeliomorpha carlsbergi, Taenidium isp. and Taenidium barretti. Additionally, rhizoliths were observed. Six ichnoassemblages were distinguished: overbank facies with (1) Rhizolith ichnoassemblage in a low-energy floodplain environment and (2) Scoyenia-Palaeophycus ichnoassemblage in crevasse splay deposits. The fluvial ichnoassociation is of moderate ichnodiversity consisting of the following assemblages: (3) Arenicolites, developed under higher flow velocities of active channels, (4) Taenidium-Scoyenia, formed by the colonisation of inactive channels, (5) Arenicolites-horizontal meniscate burrows, reflecting a rapid transition between active and abandoned channels and (6) Lockeia-vertebrate footprint, formed in littoral lakes. The Aglegal and Irohalene members indicate climatic shifts between arid dry, semiarid and subhumid in a dryland river environment. The sudden onset and the high frequency of lacustrine deposits in the lower Irohalene Member point to a rapid climate change from dry to intermittent wet and dry. This change is discussed in terms of the Carnian Pluvial Event.

Triassic Revolution

The Triassic has long been recognized as a time during which marine and terrestrial ecosystems modernized dramatically, and it seems to have been a two-step process. First, recovery from the Permian-Triassic mass extinction (PTME) was a time of extraordinary renewal and novelty, and these processes of change were enhanced, it seems, by the effects of the Carnian Pluvial Episode (CPE). After the CPE, in the oceans, not only did the carbonate factory begin to change towards its modern form, but also arguably the Mesozoic Marine Revolution (MMR) speeded up. When the MMR was proposed it was seen as a process that occurred in the Late Jurassic and Cretaceous, as modern crustaceans, gastropods, and fishes enhanced predator-prey arms races. New evidence from China and elsewhere suggests in fact the MMR was already underway in the Middle and Late Triassic, and so was coincident with Sepkoski’s classic idea that Paleozoic faunas were replaced by Modern marine faunas from the beginning of the Triassic. On land, ongoing competition between synapsids and archosauromorphs through the Triassic was marked by a posture shift from sprawling to erect, and a shift in physiology to warm-bloodedness, with insulating skin coverings of hair and feathers. Dinosaurs, for example, originated in the Early or Middle Triassic, but did not diversify until after the CPE. These arms races, the MMR in the sea, and the endothermy shift in tetrapods, were triggered by the PTME, and then enhanced by the CPE.

Paleoenvironmental and Biotic Changes in the Late Triassic of Argentina: Testing Hypotheses of Abiotic Forcing at the Basin Scale

Paleoenvironmental factors such as climate change are often hypothesized as critical for ecosystem changes over evolutionary time scales. Theoretically, these changes should be observable in the fossil record, but the robust linkage of biotic shifts to climate events remains difficult. The Late Triassic Period is an ideal interval for testing such hypotheses within terrestrial ecosystems because of a number of large-scale climate events, such as the Carnian Pluvial Episode (CPE), and a rich, well-studied fossil record. Nonetheless, at regional to global scales, few linkages have been identified during most of the Late Triassic. Here, we synthesize a multi-proxy basin-scale dataset of paleoenvironmental data, including new information from clay mineralogy and paleosol major- and trace-element geochemistry, to understand paleoclimate changes in the Ischigualasto-Villa Unión Basin of northwestern Argentina. In combination with diversity and relative abundance information from the well-sampled plant and tetrapod fossil record in the basin, we then use accepted evolutionary models of abiotic forcing of changes in ecosystems to test previously proposed hypotheses of floral and faunal variations at a basin scale. We find that although many patterns are best explained by sampling issues and taphonomy, pseudosuchian archosaur diversity and rhynchosaur relative abundance conform to predictions of paleoenvironmental forcing as the climate changed from warmer, drier conditions to more temperate humid conditions. These data demonstrate how high-resolution multi-proxy data and a well-sampled fossil record at a basin-scale can be used to test hypotheses of abiotic forcing of ecosystems in deep time, and highlights where future efforts should be directed in terms of filling data gaps and testing new hypotheses.

Palynological record of the Carnian Pluvial Episode from the northwestern Sichuan Basin, SW China

The prevailing arid Late Triassic climate was interrupted by a humid Carnian Pluvial Episode (CPE) during the mid-Carnian period. In this study, a palynological study was conducted for the Ma'antang Formation (Carnian) from the northwestern Sichuan Basin, SW China, in the eastern Tethys. The study reveals dominance of terrestrial palynomorphs, and two palynological assemblage zones were identified. Palynofloras are well-presented by dominant ferns (especially Dipteridaceae/Matoniaceae), with less abundant lycopsids, conifers, cycadophytes/ginkgophytes and seed ferns. Overwhelming predominance of wet Lowland SEG and hygrophyte elements, and increased Lowland/Hinterland as well as hygrophyte/xerophyte ratios observed in Units 2–4 of the Ma'antang Formation, suggesting intensified humidity during the Julian 2 in this area. This study presents the first palynological evidence for vegetation changes in South China during the CPE, and correlates well with observations from North China as well as western Tethys, thus further supports worldwide impact of humid climate associated with the CPE.