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

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&#8211;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 (&#948;13Corg&#160;and &#948;13Ccarb) combined to Rock-Eval data for the upper Toarcian&#8211;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 &#948;13C 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 &#948;13C record, including previously identified &#948;13C 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.&#160;

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

Geological Society of America Bulletin ◽

10.1130/b35228.1 ◽

2019 ◽

Vol 132 (5-6) ◽

pp. 1106-1118 ◽

Cited By ~ 1

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.

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Evidence for repeated and global palaeoenvironmental perturbations during the Aalenian

10.5194/egusphere-egu2020-9527 ◽

2020 ◽

Author(s):

Alicia Fantasia ◽

Thierry Adatte ◽

Jorge E. Spangenberg ◽

Nicolas Thibault ◽

Emanuela Mattioli ◽

...

Keyword(s):

High Resolution ◽

Carbon Cycle ◽

Isotope Composition ◽

Clay Fraction ◽

Time Interval ◽

Orbital Parameters ◽

Oceanic Anoxic Event ◽

Bulk Organic Matter ◽

Rock Eval ◽

Palaeoenvironmental Changes

Over the last decades, studies on Jurassic palaeoenvironments have been mostly focussed on the early Toarcian as this latter was marked by the Toarcian Oceanic Anoxic Event (T-OAE; ca. 183 Ma), which was one of the most extreme hyperthermal of the Phanerozoic. Hence, little is know about palaeoclimatic and palaeoenvironmental changes during the Aalenian time interval, although it is likely marked by an abrupt cooling in the aftermath of the Toarcian warm mode. Available palaeontological and geochemical datasets suggest that the Aalenian is also characterized by faunal turnovers and potential carbon-cycle perturbations. Despite those evidence, there is still no consensus about the modality of Aalenian palaeoenvironmental and palaeoclimatic changes as well as their potential triggering mechanisms. In addition, data from outside Europe are absent, leading to large uncertainties whether the observed changes are of gobal significance.&#160;In this study, we focus on the upper Toarcian&#8211;lower Bajocian interval of two marl/limestone alternation successions, namely Le Brusquet (Vocontian Basin, SE France) and El Pe&#241;on (Andean Basin, N Chile). Palaeoenvironmental and palaeoclimatic conditions are inferred based on high-resolution mineralogical (whole-rock and clay fraction) and geochemical (carbon isotopes, Rock-Eval pyrolysis, phosphorus, mercury) analyses. Additionaly, we provide a cyclostratigraphic framework for the Aalenian based on high-resolution magnetic susceptibility spectral analysis. The carbon isotope composition of bulk organic matter reveals evident correlatable fluctuations between sites from both hemispheres, providing the first evidence that the carbon cycle was globally and repeatedely disturbed during the Aalenian. The Toarcian&#8211;Aalenian transition is associated with a decrease in detrital and nutrient input (phosphorus), which is likely related to the shift towards the Aalenian cool mode. Interestingly, the middle&#8211;upper Aalenian transition is characterized by a sharp increase in terrigenous and nutrient influxes suggesting a more humid and warmer episode. The concomitance between strongly expressed precession cycles and palaeoenvironmental changes suggests moreover the influence of orbital parameters on the Aalenian sedimentary record.

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Requirements for An International Radiocarbon Soils Database

Radiocarbon ◽

10.1017/s0033822200017549 ◽

1996 ◽

Vol 38 (2) ◽

pp. 177-180 ◽

Cited By ~ 4

Author(s):

Peter Becker-Heidmann

Keyword(s):

High Resolution ◽

Carbon Cycle ◽

Global Carbon Cycle ◽

Carbon Pools ◽

Biosphere Model ◽

Global Carbon ◽

Global Grid

Up to now, Global Carbon Cycle Models (GCCM) have only represented the soil and biosphere in a very simplified way. For example, the High Resolution Biosphere Model (HRBM) (Esser 1987; Esser and Lautenschlager 1994) distinguishes five subreservoirs and determines the fluxes between them for selected area of a global grid. The models have not yet been sufficiently tested against global observations. Such testing is difficult because the observed variables are in turn dependent on the behavior of other geological carbon pools, e.g., the atmosphere and ocean.

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An open marine record of the Toarcian oceanic anoxic event

Solid Earth Discussions ◽

10.5194/sed-3-385-2011 ◽

2011 ◽

Vol 3 (1) ◽

pp. 385-410 ◽

Cited By ~ 17

Author(s):

D. R. Gröcke ◽

R. S. Hori ◽

J. Trabucho-Alexandre ◽

D. B. Kemp ◽

L. Schwark

Keyword(s):

Organic Matter ◽

Carbon Cycle ◽

Carbon Isotope ◽

Isotope Composition ◽

Global Carbon Cycle ◽

Open Ocean ◽

Black Shales ◽

Oceanic Anoxic Event ◽

Anoxic Event ◽

Global Carbon

Abstract. Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic-rich sediments (black shales) and significant perturbations in the global carbon cycle. The expression of these perturbations is globally recorded in sediments as excursions in the carbon isotope record irrespective of lithology or depositional environment. During the Early Toarcian, black shales were deposited on the epi- and peri-continental shelves of Pangaea and these sedimentary rocks are associated with a pronounced (ca. 7‰) negative (organic) carbon isotope excursion (CIE) which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the Early Toarcian is thought to represent an oceanic anoxic event (the T-OAE). Associated with this event, there were pronounced perturbations in global weathering rates and seawater temperatures. Although it is commonly asserted that the T-OAE is a global event and that the distribution of black shales is likewise global, an isotopic and/or organic-rich expression of this event has as yet only been recognized on epi- and peri-continental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (δ13Corg) of Early Toarcian cherts from Japan that were deposited in the open Panthalassa Ocean was analysed. The results show the presence of a major (>6‰) negative excursion in δ13Corg that, based on radiolarian biostratigraphy, is a correlative of the Early Toarcian negative CIE known from European epicontinental strata. Furthermore, a secondary ca. −2‰ excursion in δ13Corg is also recognized lower in the studied succession that, within the current biostratigraphical resolution, is likely to represent the excursion that occurs close to the Pliensbachian/Toarcian boundary and which is also recorded in European epicontinental successions. These results from the open ocean realm suggest that, in conjunction with other previously published datasets, these major Early Jurassic carbon cycle perturbations affected all active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric). An extremely negative δ13Corg value (−57‰) during the peak of the T-OAE is also reported, which suggests that the inferred open ocean mid-water oxygen minimum layer within which these sediments are thought to have been deposited was highly enriched in methanotrophic bacteria, since these organisms are the only plausible producers of such 12C-enriched organic matter.

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Effects of simulated acid rain on soil respiration and its components in a subtropical mixed conifer and broadleaf forest in southern China

Environmental Science Processes & Impacts ◽

10.1039/c5em00434a ◽

2016 ◽

Vol 18 (2) ◽

pp. 246-255 ◽

Cited By ~ 7

Author(s):

Guohua Liang ◽

Dafeng Hui ◽

Xiaoying Wu ◽

Jianping Wu ◽

Juxiu Liu ◽

...

Keyword(s):

Soil Respiration ◽

Carbon Cycle ◽

Environmental Changes ◽

Southern China ◽

Global Carbon Cycle ◽

Simulated Acid Rain ◽

Mixed Conifer ◽

Major Pathway ◽

Broadleaf Forest ◽

Global Carbon

Soil respiration is a major pathway in the global carbon cycle and its response to environmental changes is an increasing concern.

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Astronomical constraints on global carbon-cycle perturbation during Oceanic Anoxic Event 2 (OAE2)

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2017.01.007 ◽

2017 ◽

Vol 462 ◽

pp. 35-46 ◽

Cited By ~ 24

Author(s):

Yong-Xiang Li ◽

Isabel P. Montañez ◽

Zhonghui Liu ◽

Lifeng Ma

Keyword(s):

Carbon Cycle ◽

Global Carbon Cycle ◽

Oceanic Anoxic Event ◽

Oceanic Anoxic Event 2 ◽

Anoxic Event ◽

Global Carbon

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Climate forcing of terrestrial carbon sink during the Middle Jurassic greenhouse climate: Chronostratigraphic analysis of the Yan’an Formation, Ordos Basin, North China

Geological Society of America Bulletin ◽

10.1130/b35765.1 ◽

2020 ◽

Author(s):

Zhihui Zhang ◽

Tiantian Wang ◽

Jahandar Ramezani ◽

Dawei Lv ◽

Chengshan Wang

Keyword(s):

Carbon Cycle ◽

Middle Jurassic ◽

Carbon Sink ◽

Ordos Basin ◽

Global Carbon Cycle ◽

Central China ◽

Terrestrial Carbon ◽

The Ordos Basin ◽

Terrestrial Carbon Sink ◽

Global Carbon

Exploring the relationship between coal deposits as an important terrestrial carbon sink and orbital forcing of climate is critical for understanding the global carbon cycle and climate change. The Jurassic greenhouse period, characterized by extensive coal reserves widely distributed in the mid-latitude terrestrial basins, marks a significant coal-forming interval in Earth’s history. However, understanding of the processes that controlled the formation and distribution of coal at this time is inadequate. The Yan’an Formation of the Ordos Basin in north central China is among the largest and most extensively studied Jurassic coal reservoirs of the world. Here we establish a high-resolution age framework for the Yan’an Formation derived from integrated, high-precision U-Pb zircon geochronology using chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) on interstratified ash beds and cyclostratigraphy based on centimeter-scale magnetic susceptibility. Accordingly, the main coal-forming interval of the Yan’an Formation spanned ca. 174.0 Ma to <171.7 Ma, which coincided with the onset of the Middle Jurassic. The spectral analyses of the Yan’an Formation coal seams demonstrate a strong correlation to minima in the 405 k.y. orbital eccentricity cycles, suggesting a strong climate control on lake level fluctuations and clastic sediment input. Finally, we explore the cyclicity of a large set of published marine carbon isotope data from western Tethys and its phase relationship to cyclic coal deposition in the Ordos Basin. Our resutls underscore the role of terrestrial organic carbon burial in the global carbon cycle during the Middle Jurassic.

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An open ocean record of the Toarcian oceanic anoxic event

Solid Earth ◽

10.5194/se-2-245-2011 ◽

2011 ◽

Vol 2 (2) ◽

pp. 245-257 ◽

Cited By ~ 63

Author(s):

D. R. Gröcke ◽

R. S. Hori ◽

J. Trabucho-Alexandre ◽

D. B. Kemp ◽

L. Schwark

Keyword(s):

Organic Matter ◽

Carbon Cycle ◽

Carbon Isotope ◽

Isotope Composition ◽

Global Carbon Cycle ◽

Open Ocean ◽

Black Shales ◽

Oceanic Anoxic Event ◽

Anoxic Event ◽

Global Carbon

Abstract. Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic matter-rich sediments (black shales) and significant perturbations in the global carbon cycle. These perturbations are globally recorded in sediments as carbon isotope excursions irrespective of lithology and depositional environment. During the early Toarcian, black shales were deposited on the epi- and pericontinental shelves of Pangaea, and these sedimentary rocks are associated with a pronounced (ca. 7 ‰) negative (organic) carbon isotope excursion (CIE) which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the lower Toarcian is thought to represent an oceanic anoxic event (the T-OAE). If the T-OAE was indeed a global event, an isotopic expression of this event should be found beyond the epi- and pericontinental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (δ13Corg of lower Toarcian organic matter-rich cherts from Japan, deposited in the open Panthalassa Ocean, was analysed. The results show the presence of a major (>6 ‰) negative excursion in δ13Corg that, based on radiolarian biostratigraphy, is a correlative of the lower Toarcian negative CIE known from Pangaean epi- and pericontinental strata. A smaller negative excursion in δ13Corg (ca. 2 ‰) is recognized lower in the studied succession. This excursion may, within the current biostratigraphic resolution, represent the excursion recorded in European epicontinental successions close to the Pliensbachian/Toarcian boundary. These results from the open ocean realm suggest, in conjunction with other previously published datasets, that these Early Jurassic carbon cycle perturbations affected the active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric).

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