Search results for " Triassic"

An enormous sulfur isotope excursion indicates marine anoxia during the end-Triassic mass extinction

2020

The role of ocean anoxia as a cause of the end-Triassic marine mass extinction is widely debated. Here, we present carbonate-associated sulfate δ34S data from sections spanning the Late Triassic–Early Jurassic transition, which document synchronous large positive excursions on a global scale occurring in ~50 thousand years. Biogeochemical modeling demonstrates that this S isotope perturbation is best explained by a fivefold increase in global pyrite burial, consistent with large-scale development of marine anoxia on the Panthalassa margin and northwest European shelf. This pyrite burial event coincides with the loss of Triassic taxa seen in the studied sections. Modeling results also indica…

Mercury contents and isotope ratios from diverse depositional environments across the Triassic–Jurassic Boundary: Towards a more robust mercury proxy…

2021

Abstract Mercury is gaining prominence as a proxy for large igneous province (LIP) volcanism in the sedimentary record. Despite temporal overlap between some mass extinctions and LIPs, the precise timing of magmatism relative to major ecological and environmental change is difficult to untangle, especially in marine settings. Changes in the relative contents of Hg in sedimentary rocks through time, or ‘Hg anomalies’, can help resolve the timing of LIP activity and marine extinctions. However, major questions remain unanswered about the fidelity of Hg as a proxy for LIP magmatism. In particular, depositional (e.g., redox) and post-depositional (e.g., oxidative weathering) processes can affec…

Positive Sulfate Sulfur Isotope Excursion Indicates Large-Scale Pyrite Burial and Marine Anoxia during the End–Triassic Mass Extinction

2020

The late Rhaetian–early Hettangian transition is characterised by the emplacement of Central Atlantic magmatic province and associated climatic effects, coincident with a severe biotic crisis (~201.5 Ma). The oxygen deficiency in the ocean realm is possibly linked to this significant loss in marine biodiversity. However, direct evidence of contemporaneous development of marine anoxia on a global scale has been lacking and the relationship between oxygen and extinction is unclear. Here we report carbonate-associated sulfate δ34S data from three sections across the Late Triassic–Early Jurassic transition. We find synchronous large positive δ34S shifts with a magnitude of >10‰ in the latest…

Bivalves and evolutionary resilience: Old skills and new strategies to recover from the P/T and T/J extinction events

2011

Diversity dynamics among bivalves during the Triassic and Early Jurassic provides the opportunity to analyse the recovery patterns after two mass extinctions: Permian/Triassic and Triassic/Jurassic (T/J). The results presented here are based on a newly compiled worldwide genus-level database and are contrasted to the main morphological characters of the different taxonomical (orders and their constituent families and genera) and ecological groups. Many of such morphological characters are innovations appearing during the time span considered. Diversity and evolutionary rates were assessed and compared between these groups. During the Early Triassic there was a slow recovery, dominated by ep…

The genus Palaeolituonella (Foraminifer) and description of Palaeolituonella angulata nov. sp. from Upper Triassic reef limestones of the Tethys

2009

The Potential Geosite of the “Libeccio Antico” Quarries: a Sedimentological and Stratigraphic Characterisation of Ornamental Stone from Mt Cocuccio, …

2018

The Custonaci marble district of western Sicily is known for the production of a valuable ornamental stone that has been, and nowadays is exploited due to its suitable properties and aesthetic qualities. The “Libeccio Antico” was, among the “marbles”, the most appreciated ornamental stone during the Baroque Age (the XVII–XVIII centuries), due to its strong polychrome contrasts from ivory to yellow, green or dark red. This polychrome pattern is the result of dissolution processes that involved an Upper Triassic peritidal limestone. The varicoloured sediments in paleocavities, collapse breccias, paleosols and neptunian dykes that occur in the “Libeccio Antico” represent the peculiar character…

A diagenetic control on the Early Triassic Smithian-Spathian carbon isotopic excursions recorded in the marine settings of the Thaynes Group (Utah, U…

2016

17 pages; International audience; n the aftermath of the end-Permian mass extinction, Early Triassic sediments record some of the largest Phanerozoic carbon isotopic excursions. Among them, a global Smithian-negative carbonate carbon isotope excursion has been identified, followed by an abrupt increase across the Smithian–Spathian boundary (SSB; ~250.8 Myr ago). This chemostratigraphic evolution is associated with palaeontological evidence that indicate a major collapse of terrestrial and marine ecosystems during the Late Smithian. It is commonly assumed that Smithian and Spathian isotopic variations are intimately linked to major perturbations in the exogenic carbon reservoir. We present p…

Comment on "Lethally hot temperatures during the Early Triassic greenhouse".

2013

Sun et al . (Reports, 19 October 2012, p. 366) reconstructed Permian to Middle Triassic equatorial seawater temperatures. After correct temporal positioning of their data points, their presumed trends of temperature changes, and hence their assumption of a one-to-one relationship between putative "lethally hot" seawater temperatures and a disputable equatorial "eclipse" of some organisms, are no longer supported by their data.

First xiphosuran traceway in the middle Muschelkalk facies (Middle Triassic) of the Catalan Basin (NE Iberian Peninsula)

2021

In the last decade, the first ichnoassamblages from the middle Muschelkalk facies (upper Anisian-middle Ladinian) of the Catalan Basin (NE Iberian Peninsula) have been discovered. Herein, the first xiphosuran trace fossils are described from the locality of Penya Rubí, a newly discovered ichnosite from the Catalan Basin. The finding opens a window into peri-Tethys ecosystems with coastal influence. The traceway is referred to the ichnogenus Kouphichnium, a locomotion trace attributed to xiphosurans. The traceway preserves telson grooves and different imprint morphologies from the various appendages. The traceway pattern and arrangement of the different traces suggest a crawling locomotion s…

Sedimentology, petrography and geochemistry of a limestone breccia (Pietra di Billiemi) from NW Sicily, Italy: implications for evolution of the Teth…

2009

In this study, the Pietra di Billiemi, a famous dimension stone, is investigated because it records the tectonic evolution of the south Tethys continental margin and preserves a record of major environmental changes occurring near the Triassic/Jurassic boundary. The Pietra di Billiemi is a grey, coarse-grained and clast-supported limestone breccia cropping out in an area of the Palermo Mountains representing a segment of the Apennine–Maghrebian chain in western Sicily. The rock consists of metre-sized to centimetre-sized angular clasts, derived from Upper Triassic sponge boundstones and rudstones, with a differently coloured, silt-grained matrix. Fitted fragments are observed commonly which…