Dynamics of a stepped carbon-isotope excursion: Ultra high-resolution study of Early Toarcian environmental change

2012 ◽  
Vol 319-320 ◽  
pp. 45-54 ◽  
Author(s):  
Michaël Hermoso ◽  
Fabrice Minoletti ◽  
Rosalind E.M. Rickaby ◽  
Stephen P. Hesselbo ◽  
François Baudin ◽  
...  
Keyword(s):  
High Resolution ◽  
Environmental Change ◽  
Carbon Isotope ◽  
Carbon Isotope Excursion ◽  
Resolution Study

scholarly journals New Chronostratigraphic Constraints on the Lower Jurassic Pliensbachian–Toarcian Boundary at Chacay Melehue (Neuquén Basin, Argentina)

2021 ◽  
Author(s):  
Aisha H. Al-Suwaidi ◽  
Micha Ruhl ◽  
Hugh C. Jenkyns ◽  
Susana E. Damborenea ◽  
Miguel O. Manceñido ◽  
...  
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
Volcanic Ash ◽  
Lower Jurassic ◽  
Zircon Geochronology ◽  
Organic Carbon Isotope ◽  
Carbon Isotope Excursion ◽  
Isotope Record ◽  
Age Model ◽  
Zonal Boundary

Abstract The Pliensbachian–Toarcian boundary interval is characterized by a ~3‰ negative carbon-isotope excursion (CIE) in organic and inorganic marine and terrestrial archives from sections in Europe, such as Peniche (Portugal) and Hawsker Bottoms, Yorkshire (UK). A new high-resolution organic-carbon isotope record, illustrating the same chemostratigraphic feature, is presented from the Southern Hemisphere Arroyo Chacay Melehue section, Chos Malal, Argentina, corroborating the global significance of this disturbance to the carbon cycle. The negative carbon-isotope excursion, mercury and organic-matter enrichment is accompanied by high-resolution ammonite and nannofossil biostratigraphy together with U-Pb CA-ID-TIMS geochronology derived from intercalated volcanic ash beds. A new age of ~183.71 ± 0.40/-0.51 Ma for the Pliensbachian–Toarcian boundary, and 182.77 +0.11/-0.21 for the tenuicostatum–serpentinum zonal boundary, is assigned based on high-precision U-Pb zircon geochronology and a Bayesian Markov chain Monte Carlo (MCMC) stratigraphic age model.

scholarly journals Carbon isotopes, stratigraphy, and environmental change: the Middle–Upper Cambrian Positive Excursion (SPICE) in Port au Port Group, western Newfoundland, Canada

2018 ◽  
Vol 55 (11) ◽  
pp. 1209-1222 ◽  
Author(s):  
Rosalia Barili ◽  
Joyce Elaine Neilson ◽  
Alexander Thomas Brasier ◽  
Karin Goldberg ◽  
Tatiana Pastro Bardola ◽  
...  
Keyword(s):  
North America ◽  
Environmental Change ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Carbonate Rocks ◽  
Isotopic Signature ◽  
Upper Cambrian ◽  
Carbon Isotopic ◽  
Carbon Isotope Excursion ◽  
Diagenetic Environment

In many basins, Upper Cambrian carbonate successions display intervals with a positive carbon isotope excursion (CIE) of up to +5‰. In North America, this marks the boundary between the Sauk II–III super-sequences. A Steptoean positive carbon isotope excursion (SPICE) locality previously identified in the Port au Port peninsula, western Newfoundland, has been revisited and an additional potential SPICE locality found. In both locations, a CIE is found to be associated with a prominent bioherm and sandstone layer within a sequence of carbonate rocks. At March Point columnar stromatolites occur, whereas at Felix Cove thrombolites can be seen. In the latter, the sandstone immediately overlies the thrombolites coincident with the CIE, whereas at March Point a dolomitized grainstone occurs above the stromatolites. The sandstone at this locality post-dates the CIE. Although lower than the SPICE in some localities, a positive CIE is present in both sections: March Point (+1.1‰) and Felix Cove (+1.8‰). Additionally, δ13Corg rises from −30.0‰ to −22.0‰ at March Point and from −27‰ to −24.0‰ at Felix Cove and, in accordance with previously published work, we suggest that this could be the SPICE. Comparison of the stratigraphy and petrography between the two localities suggest that both depositional and diagenetic factors could have influenced the nature of the interpreted SPICE in Newfoundland. It is also possible that the local carbon isotopic signature may have been influenced by a semi-restricted depositional and early diagenetic environment related to the paleogeographic configuration rather than the global marine excursion.

Extending the record of the Lomagundi–Jatuli carbon isotope excursion in the Labrador Trough, Canada

2020 ◽  
Vol 57 (9) ◽  
pp. 1089-1102
Author(s):  
Malcolm S.W. Hodgskiss ◽  
Kelsey G. Lamothe ◽  
Galen P. Halverson ◽  
Erik A. Sperling
Keyword(s):  
High Resolution ◽  
Water Column ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Large Range ◽  
Authigenic Carbonate ◽  
Elemental Ratios ◽  
Carbonate Carbon ◽  
Carbon Isotope Excursion ◽  
Isotope Analyses

The Labrador Trough in northern Québec and Labrador is a 900 km long Rhyacian–Orosirian orogenic belt containing mixed sedimentary–volcanic successions. Despite having been studied intensively since the 1940s, relatively few chemostratigraphic studies have been conducted. To improve our understanding of the Labrador Trough in the context of Earth history, and better constrain the local record of the Lomagundi–Jatuli carbon isotope excursion, high-resolution sampling and carbon isotope analyses of the Le Fer and Denault formations were conducted. Carbonate carbon isotopes (δ13C) in the Le Fer Formation record a large range in values from −4.4‰ to +6.9‰. This large range is likely attributable to a combination of post-depositional alteration and variable abundance of authigenic carbonate minerals; elemental ratios suggest that the most 13C-enriched samples reflect the composition of the water column at the time of deposition. Cumulatively, these data suggest that the Lomagundi–Jatuli Excursion was ongoing during deposition of the Le Fer Formation, approximately 2 km higher in the stratigraphy than previously recognised. However, the possibility of a post-Lomagundi–Jatuli Excursion carbon isotope event cannot conclusively be ruled out. The directly overlying Denault Formation records a range in δ13C values, from −0.5‰ to +4.3‰, suggesting that it was deposited after the conclusion of the Lomagundi–Jatuli Excursion and that the contact between the Le Fer and Denault formations occurred sometime during the transition out of the Lomagundi–Jatuli Excursion, ca. 2106 to 2057 Ma.

scholarly journals Carbon isotope (δ13Ccarb) and facies variability at the Wenlock–Ludlow boundary (Silurian) of the Midland Platform, UK

2016 ◽  
Vol 53 (7) ◽  
pp. 725-730 ◽  
Author(s):  
John A. Blain ◽  
David C. Ray ◽  
James R. Wheeley
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Carbon Isotope ◽  
Carbonate Platform ◽  
Temporal Variations ◽  
Spatial Variations ◽  
Sea Level Fluctuations ◽  
Depositional Settings ◽  
Carbon Isotope Excursion

The Wenlock–Ludlow series boundary (Silurian) has been recognized as a time of pronounced sea-level rise and the end of a globally recognized Late Homerian Stage (Mulde) positive carbon isotope excursion (CIE). However, the precise timing and synchronicity of the end of the excursion with respect to the Wenlock–Ludlow boundary is debated. Within the type Wenlock and Ludlow areas (UK), high-resolution δ13Ccarb isotope data are presented across the Wenlock–Ludlow boundary, and within a range of carbonate platform settings. Correlation between sections and depositional settings has been based upon the characteristics of high-order sea-level fluctuations (parasequences). Comparisons between parasequence-bounded δ13Ccarb values reveal clear spatial variations, with lighter values recorded from more distal settings and heavier values from shallower settings. Temporal variations in the δ13Ccarb values are also documented and appear to reflect local variations in carbonate provenance and productivity in response to sea-level rise. While δ13Ccarb values converge in all sections towards the Wenlock–Ludlow boundary, the apparent end of the Mulde CIE appears diachronous and is progressively older within more distal settings.

DECIPHERING THE RECORD OF BIOLOGIC AND ENVIRONMENTAL CHANGE DURING THE LATER CAMBRIAN STEPTOEAN POSITIVE CARBON ISOTOPE EXCURSION

2017 ◽  
Author(s):  
Benjamin C. Gill ◽  
◽  
Matthew A. LeRoy ◽  
Angela Gerhardt ◽  
Theodore R. Them ◽  
...  
Keyword(s):  
Environmental Change ◽  
Carbon Isotope ◽  
Carbon Isotope Excursion

scholarly journals High-resolution correlation of the Homerian carbon isotope excursion (Silurian) across the interior of the Midland Platform (Avalonia), UK

2019 ◽  
Vol 157 (4) ◽  
pp. 603-620
Author(s):  
David C. Ray ◽  
Emilia Jarochowska ◽  
Philipp Röstel ◽  
Graham Worton ◽  
Axel Munnecke ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Carbon Isotope ◽  
Depositional Environment ◽  
Sea Level Change ◽  
The West ◽  
Relative Sea Level ◽  
Level Change ◽  
Carbon Isotope Excursion ◽  
West Midlands

AbstractNew δ13Ccarb and microfacies data from Hereford–Worcestershire and the West Midlands allow for a detailed examination of variations in the Homerian carbon isotope excursion (Silurian) and depositional environment within the Much Wenlock Limestone Formation of the Midland Platform (Avalonia), UK. These comparisons have been aided by a detailed sequence-stratigraphic and bentonite correlation framework. Microfacies analysis has identified regional differences in relative sea-level change and indicates an overall shallowing of the carbonate platform interior from Hereford–Worcestershire to the West Midlands. Based upon the maximum δ13Ccarb values for the lower and upper peaks of the Homerian carbon isotope excursion (CIE), the shallower depositional setting of the West Midlands is associated with values that are 0.7 ‰ and 0.8 ‰ higher than in Hereford–Worcestershire. At the scale of parasequences the effect of depositional environment upon δ13Ccarb values can also be observed, with a conspicuous offset in the position of the trough in δ13Ccarb values between the peaks of the Homerian CIE. This offset can be accounted for by differences in relative sea-level change and carbonate production rates. While such differences complicate the use of CIEs as a means of high-resolution correlation, and caution against correlations based purely upon the isotopic signature, it is clear that a careful analysis of the depositional environment can account for such differences and thereby improve the use of carbon isotopic curves as a means of correlation.

scholarly journals Calibrating the coevolution of Ediacaran life and environment

2020 ◽  
Vol 117 (29) ◽  
pp. 16824-16830 ◽  
Author(s):  
Alan D. Rooney ◽  
Marjorie D. Cantine ◽  
Kristin D. Bergmann ◽  
Irene Gómez-Pérez ◽  
Badar Al Baloushi ◽  
...  
Keyword(s):  
Environmental Change ◽  
Carbon Isotope ◽  
Biogeochemical Cycles ◽  
Redox Conditions ◽  
Driving Mechanism ◽  
Testing Hypotheses ◽  
Plate Motions ◽  
Evolutionary Innovation ◽  
Carbon Isotope Excursion ◽  
Global Biogeochemical Cycles

The rise of animals occurred during an interval of Earth history that witnessed dynamic marine redox conditions, potentially rapid plate motions, and uniquely large perturbations to global biogeochemical cycles. The largest of these perturbations, the Shuram carbon isotope excursion, has been invoked as a driving mechanism for Ediacaran environmental change, possibly linked with evolutionary innovation or extinction. However, there are a number of controversies surrounding the Shuram, including its timing, duration, and role in the concomitant biological and biogeochemical upheavals. Here we present radioisotopic dates bracketing the Shuram on two separate paleocontinents; our results are consistent with a global and synchronous event between 574.0 ± 4.7 and 567.3 ± 3.0 Ma. These dates support the interpretation that the Shuram is a primary and synchronous event postdating the Gaskiers glaciation. In addition, our Re-Os ages suggest that the appearance of Ediacaran macrofossils in northwestern Canada is identical, within uncertainty, to similar macrofossils from the Conception Group of Newfoundland, highlighting the coeval appearance of macroscopic metazoans across two paleocontinents. Our temporal framework for the terminal Proterozoic is a critical step for testing hypotheses related to extreme carbon isotope excursions and their role in the evolution of complex life.

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