Was the Late Ordovician mass extinction truly exceptional?

Trends in Ecology & Evolution, Год журнала: 2023, Номер 38(9), С. 812 - 821

Опубликована: Май 12, 2023

Язык: Английский

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Productivity and redox influences on the late Ordovician ‘Katian Extinction’ and ‘early Silurian Recovery’

Palaeogeography Palaeoclimatology Palaeoecology, Год журнала: 2024, Номер 642, С. 112176 - 112176

Опубликована: Март 30, 2024

Язык: Английский

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Assessment of Hg Speciation Changes in the Sedimentary Rock Record From Thermal Desorption Characteristics

Geochemistry Geophysics Geosystems, Год журнала: 2024, Номер 25(4)

Опубликована: Апрель 1, 2024

Abstract Sedimentary mercury (Hg) has become a widely used proxy for paleo‐volcanic activity. However, scavenging and drawdown of Hg by organic‐matter (OM) sulfides are important non‐volcanic factors determining variability in such records. Most studies, therefore, normalize total (Hg T ) to “host‐phase” (e.g., /TOC OM, /TS sulfides), with the dominant host‐phase determined based on strongest observed (linear) correlations. This approach suffers from various non‐linearities Hg‐host‐phase behavior does not account succession‐level, let alone sample‐level, speciation changes. Thermal desorption characteristics or “profiles” (TDPs) many species during pyrolysis analysis well‐established applications including distinguishing between OM‐bound different oxides (sub‐)recent sediments. We explore use TDPs geological sediment (rock) samples illustrate presence multiple release phases species)—correlated geochemical host‐phase—in (almost) all 65 analyzed Tithonian (146–145 Ma) silt mudrock samples. By quantifying each phase every sample, we find TOC concentration may determine ∼60% first (lower temperature) TDP phase: stark difference released these samples, where ∼20% variation is explained variability. provide insight sample‐level demonstrate that, while common assumption single‐phase sedimentary rocks problematic, differences can be detected, quantified, accounted using commonly applied techniques—opening potential routine assessment.

Язык: Английский

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C, N, Hg isotopes and elemental chemostratigraphy across the Ordovician–Silurian transition in the Argentine Precordillera: Implications for the link between volcanism and extinctions

Gondwana Research, Год журнала: 2024, Номер 133, С. 270 - 296

Опубликована: Июнь 21, 2024

Язык: Английский

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The redox transformation in the Yangtze Sea across the Ordovician-Silurian transition: Evidence from zinc isotopes in organic-rich shales

Journal of Asian Earth Sciences, Год журнала: 2025, Номер unknown, С. 106579 - 106579

Опубликована: Март 1, 2025

Язык: Английский

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Mechanisms of global climate change during the five major mass extinctions

Scientific Reports, Год журнала: 2025, Номер 15(1)

Опубликована: Май 12, 2025

Since the emergence of diverse animal phyla around 500 million years ago, five major mass extinction events have occurred, each coinciding with abnormal climate changes. We analyzed sedimentary organic molecules from first and least understood event at end Ordovician period. divided all extinctions into two phases each, totaling ten events, examined relationship between shifts "coronene index"-an indicator heating temperatures in rocks caused by volcanic activity or meteorite impacts. As a result, we found that four began global cooling ended warming, while one started an unknown anomaly also warming. During initial phases, showed low-temperature heating, high-temperature, moderate-temperature. All subsequent warming moderate-temperature heating. These findings suggest large-scale eruptions impacts heated sulfides, sulfates, hydrocarbons varying temperatures, releasing SO2 soot stratosphere, blocking sunlight, triggering extinction. This was followed moderate carbonates, increasing CO2 emissions driving long-term leading to secondary events.

Язык: Английский

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Spatiotemporal distribution of global mercury enrichments through the Paleocene-Eocene Thermal Maximum and links to volcanism

Earth-Science Reviews, Год журнала: 2023, Номер 248, С. 104647 - 104647

Опубликована: Дек. 7, 2023

Язык: Английский

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Late Ordovician ironstone and its relation to ocean redox instability, climate and glaciation

Sedimentology, Год журнала: 2024, Номер unknown

Опубликована: Ноя. 26, 2024

Abstract The Upper Ordovician (Katian) Neda Formation, a phosphatic ironstone, records widespread but short‐lived shift to ferruginous waters across vast epicontinental area. Lithofacies and stratigraphic reappraisal indicate that ironstone deposition occurred on storm‐dominated ramp when coastal upwelling emplaced eutrophic mixed with oxygenated surface water. This stimulated primary productivity precipitated Fe‐(oxyhydr)oxides in the water column formed phosphorous iron‐rich mud. Remobilization of iron beneath seafloor led syndepositional authigenic precipitation P Fe minerals sediment, preferentially coating grains forming granular top few decimetres sediment. Formation is pronounced unconformity punctuated by laterite as sea level fell during Hirnantian Glaciation. transition from conditions interpreted have been caused an increase equator‐to‐pole temperature gradient concomitant reorganization thermohaline circulation Katian. intensified off Laurentian margin upwelled transported into midcontinent where accumulated through Sebree Trough. ironstone's coincident with, potentially by, same drivers global oceanographic biotic change Late both adds greater insight major changes oceans preceding Mass Extinction Glaciation, also furthers emerging model tying throughout Phanerozoic Earth system events.

Язык: Английский

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Substantial gas enrichment in shales influenced by volcanism during the Ordovician–Silurian transition

International Journal of Coal Geology, Год журнала: 2024, Номер unknown, С. 104638 - 104638

Опубликована: Окт. 1, 2024

Язык: Английский

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Enhanced Continental Weathering Triggered the Anoxia of Seawater and Mass Extinctions During the Late Ordovician

Journal of Marine Science and Engineering, Год журнала: 2024, Номер 12(12), С. 2237 - 2237

Опубликована: Дек. 5, 2024

During the Late Ordovician period, changes in climate and mass extinctions were observed; however, factors influencing these phenomena have not been fully understood. In order to understand relationships among redox water conditions, climates, Ordovician, this study analyzes chemical index of alteration (CIA) shales 87Sr/86Sr carbonate leachates as proxies weathering intensity rate (mainly from Katian Hirnantian). The results show that an enhanced (increased ratios) decreased (decreased CIA values) characterized late Katian, which might be attributed global orogenesis precipitation/runoff under warming (late-Boda warming). This contributed CO2 drawdown P. pacificus biozone, corresponding initiation cooling further glaciation. Meanwhile, weathering-induced high primary productivity could expansion anoxic seawater caused extinction. Hirnantian Glaciation was by ratios carbonates extremely low values shales, likely related exposure continents during sea level glacial grinding unweathered rocks. shows highest denudation lowest stage resulted release end

Язык: Английский

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