High-resolution correlation between contrasting early Tonian carbonate successions in NW Canada highlights pronounced global carbon isotope variations

2020 ◽  
Vol 346 ◽  
pp. 105816 ◽  
Author(s):  
J. Wilder Greenman ◽  
Robert H. Rainbird ◽  
Elizabeth C. Turner
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
Global Carbon

Organic carbon isotopes in terrestrial Permian-Triassic boundary sections of North China: Implications for global carbon cycle perturbations

2019 ◽  
Vol 132 (5-6) ◽  
pp. 1106-1118 ◽  
Author(s):  
Yuyang Wu ◽  
Jinnan Tong ◽  
Thomas J. Algeo ◽  
Daoliang Chu ◽  
Ying Cui ◽  
...  
Keyword(s):  
High Resolution ◽  
Carbon Cycle ◽  
Carbon Isotope ◽  
North China ◽  
Global Carbon Cycle ◽  
Middle Part ◽  
Triassic Boundary ◽  
Permian Mass Extinction ◽  
Permian Triassic Boundary ◽  
Global Carbon

Abstract The end-Permian mass extinction (ca. 252 Ma) represents the most severe biotic crisis of the Phanerozoic, and it was accompanied by profound environmental perturbations, especially to the global carbon cycle, as indicated by sharp negative carbon isotope excursions (CIE) in both carbonates (δ13Ccarb) and organic matter (δ13Corg). To date, carbon isotope records are mostly from marine Permian-Triassic transitional sequences with relatively few high-resolution carbon isotope profiles having been generated for terrestrial facies. Terrestrial Permian-Triassic sequences suitable for high-resolution carbon isotope study are rare globally and are difficult to correlate with better-studied marine sequences. However, carbon isotope records from continental facies are essential to a full understanding of global carbon cycle changes during the Permian-Triassic transition. Here, we present bulk δ13Corg profiles for three terrestrial sections in North China representing Permian-Triassic transitional beds. These profiles exhibit similar patterns of secular variation defining three stages: (1) a pre-CIE interval, (2) a CIE interval, characterized by a rapid negative shift of 1.7‰–2.2‰ within the middle part of the Sunjiagou Formation, and (3) a post-CIE interval. The similarity of the CIE in all three study sections facilitates correlations among them, and its presence in the Permian-Triassic transitional beds suggests that it is equivalent to the negative CIE at the Permian-Triassic boundary in the Meishan global stratotype section and point (GSSP) and in coeval marine and terrestrial sections globally. The end-Permian CIE was probably triggered by a massive release of 13C-depleted carbon from volcanogenic sources leading to elevated atmospheric pCO2, although oceanic sources of CO2 cannot be ruled out at present.

Field evidence for coal combustion links the 252 My-old Siberian Traps with global carbon disruption

2021 ◽  
Author(s):  
Linda Elkins-Tanton ◽  
Steven Grasby ◽  
Benjamin Black ◽  
Roman Veselovskiy ◽  
Omid Ardakani ◽  
...  
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Flood Basalts ◽  
Siberian Traps ◽  
Field Evidence ◽  
Carbon Isotope Excursion ◽  
Show Evidence ◽  
Volcaniclastic Rocks ◽  
Atmospheric Changes ◽  
Global Carbon

<p>The Permo-Triassic Extinction was the most severe in Earth history. The Siberian Traps eruptions are strongly implicated in the global atmospheric changes that likely drove the extinction. A sharp negative carbon isotope excursion coincides within geochronological uncertainty with the oldest dated rocks from the Norilsk section of the Siberian flood basalts. The source of this light carbon has been debated for decades.</p><p>We focused on the voluminous volcaniclastic rocks of the Siberian Traps, relatively unstudied as potential carriers of carbon-bearing gases. Over six field seasons we collected rocks from across the Siberian platform and show the first direct evidence that the earliest eruptions particularly in the southern part of the province burned large volumes of a combination of vegetation and coal. Samples from the Maymecha-Kotuy region, from the Nizhnyaya Tunguska, Podkamennaya Tunguska, and Angara Rivers all show evidence of high-temperature organic matter carbonization and combustion.</p><p>Field evidence indicates a process in which ascending magmas entrain xenoliths of coal and carbonaceous sediments that are carbonized in the subsurface and also combusted either through reduction of magmas or when exposed to the atmosphere. We demonstrate that the volume and composition of organic matter interactions with magmas may explain the global carbon isotope signal, and have significantly driven the extinction.</p>

Recurrent global carbon cycle disturbances during the Aalenian: Evidence from France and Chile

2021 ◽  
Author(s):  
Alicia Fantasia ◽  
Thierry Adatte ◽  
Jorge E. Spangenberg ◽  
Emanuela Mattioli ◽  
Enrique Bernárdez ◽  
...  
Keyword(s):  
High Resolution ◽  
Carbon Cycle ◽  
Middle Jurassic ◽  
Environmental Changes ◽  
Global Carbon Cycle ◽  
Oceanic Anoxic Event ◽  
Carbon Substrates ◽  
Rock Eval ◽  
Resolution Dataset ◽  
Global Carbon

<p>The Jurassic was punctuated by several episodes of abrupt environmental changes associated with climatic instabilities, severe biotic crisis, and perturbations of the global carbon cycle. Over the last decades, the Toarcian Oceanic Anoxic Event (Early Jurassic, ~183 Ma) and the early Bajocian Event (Middle Jurassic, ~170–168 Ma) have attracted much attention because they represent such episodes of global and severe environmental change. Bracketed in between the Toarcian and the Bajocian, the Aalenian stage (Middle Jurassic, ~174-170 Ma) has received less attention, although there is some evidence from Tethyan and Boreal records that it was a time of environmental changes marked by marine biotic turnovers. The lack of knowledge about the Aalenian palaeoenvironments leaves a gap in our understanding of the wider context of the Toarcian and Bajocian events and hence of environmental feedback mechanisms surrounding Mesozoic carbon cycle perturbations. In this study, we provide a high-resolution, biostratigraphically well-defined carbon isotope records (<em>δ</em><sup>13</sup>C<sub>org </sub>and <em>δ</em><sup>13</sup>C<sub>carb</sub>) combined to Rock-Eval data for the upper Toarcian–lower Bajocian interval from two expanded marl/limestone alternation successions from France (French Subalpine Basin) and Chile (Andean Basin). The comparison with available records from the Tethyan and Boreal domains highlights that medium-term <em>δ</em><sup>13</sup>C fluctuations are reproducible across different palaeoceanographic settings from both hemispheres and between different carbon substrates. The new high-resolution dataset highlights the complexity of the Aalenian <em>δ</em><sup>13</sup>C record, including previously identified <em>δ</em><sup>13</sup>C shifts and hitherto undescribed fluctuations. This study provides one of the most expanded high-resolution chemostratigraphic reference records for the entire Aalenian stage, and shows compelling evidence from both hemispheres that it was a time marked by recurrent perturbations to the global carbon cycle and environmental changes.</p><p> </p>

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