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

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 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.

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.

CERIUM ANOMALY ACROSS THE EARLY MISSISSIPPIAN KINDERHOOKIAN–OSAGEAN CARBON ISOTOPE EXCURSION

2019 ◽  
Author(s):  
Deborah C. Morales ◽  
◽  
Ganqing Jiang ◽  
Shichun Huang ◽  
Audrey Warren ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotope Excursion ◽  
Cerium Anomaly

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>

The recovery of early vertebrates and reef ecosystems following the late Silurian carbon isotope excursion: the Burgen outlier, Gotland, Sweden

2021 ◽  
Author(s):  
Emilia Jarochowska ◽  
Oskar Bremer ◽  
Alexandra Yiu ◽  
Tiiu Märss ◽  
Henning Blom ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Carbonate Platform ◽  
Fish Diversity ◽  
Global Environmental ◽  
Carbon Isotope Excursion ◽  
Low Diversity ◽  
Early Vertebrates ◽  
Carbonate Factory ◽  
Faunal Distribution ◽  
Rapid Regression

<p>The Ludfordian Carbon Isotope Excursion (LCIE) reached the highest known δ<sup>13</sup>C values in the Phanerozoic. It was a global environmental perturbation manifested in a rapid regression attributed to glacial eustasy. Previous studies suggested that it has also heavily affected the diversity of conodonts, early vertebrates and reef ecosystems, but the timing of the crisis and recovery remained complicated owing to the lateral variability of δ<sup>13</sup>C values in epeiric platforms and rapid facies shifts, which drove faunal distribution. One of the best records of this interval is available in the Swedish island of Gotland, which preserves tectonically undisturbed strata deposited in a Silurian tropical carbonate platform. We revisited the world-renowned collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, Stockholm, which holds the key to reconstruct the dynamics of faunal immigration and diversification following the LCIE. Here we focus on the Burgen erosional outlier, which remained a mystery, as it had been correlated with the excursion strata, but preserved a high diversity of conodonts and reefal ecosystems. We re-examined key outcrops and characterized macro- and microfacies, as well as chemostratigraphy and unpublished fauna in the collection. Strata in the Burgen outlier represent back-shoal facies of the Burgsvik Oolite Member and correspond to the Ozarkodina snajdri Conodont Biozone. The shallow-marine position compared to the more continental setting of coeval strata in southern Gotland, is reflected in the higher δ<sup>13</sup>C<sub>carb</sub> values, reaching +9.2‰. The back-shoal succession in this outcrop includes reefs, which contain a large proportion of microbial carbonates and have therefore been previously compared with low-diversity buildups developed in a stressed ecosystem. However, the framework of these reefs is built by a diverse coral-stromatoporoid-bryozoan fauna, indicating that a high microbial contribution might be a characteristic of the local carbonate factory rather than a reflection of restricted conditions. In the case of conodonts, impoverishment following the LCIE might be a product of facies preferences, as the diverse environments in the outlier yielded at least 20 of the 21 species known from the Burgsvik Formation in Gotland. Fish diversity also returned to normal levels following the LCIE with an estimated minimum of 9 species. Thelodont scales appear to dominate samples from the Burgen outlier, which is in line with previous reports. Our observations highlight how palaeoenvironmental reconstructions inform fossil niche and diversity analyses, but also how fossil museum collections continuously contribute new data on past biodiversity.</p>

Late Paleocene-Early Eocene Foraminiferal Assemblage and Carbon Isotope Excursion Indicating Hyperthermal Events in Paleotropical Succession of Northwestern India

2021 ◽  
Vol 51 (1) ◽  
pp. 4-13
Author(s):  
Sonal Khanolkar ◽  
Tathagata Roy Choudhury ◽  
Pratul Kumar Saraswati ◽  
Santanu Banerjee
Keyword(s):  
Carbon Isotope ◽  
Detrended Correspondence Analysis ◽  
Western India ◽  
Early Eocene ◽  
Foraminiferal Assemblage ◽  
Trophic Conditions ◽  
Jaisalmer Basin ◽  
Early Eocene Climatic Optimum ◽  
Late Paleocene ◽  
Carbon Isotope Excursion

ABSTRACT This study focuses on marine sediments of the late Paleocene-early Eocene (∼55.5–49 Ma) interval from the Jaisalmer Basin of western India. It demarcates the Paleocene Eocene Thermal Maximum (PETM) using foraminiferal biostratigraphy and carbon isotope stratigraphy. A negative carbon isotope excursion of 4.5‰ delineates the PETM within the basin. We demarcate five foraminiferal biofacies using the detrended correspondence analysis. These reflect characteristics of ecology, bathymetry, relative age, and environment of deposition of the foraminifera. They record the response of foraminifera to the warmth of the PETM. Biofacies A was deposited within an inner neritic setting ∼55.5 Ma and includes benthic foraminifera Haplophragmoides spp., Ammobaculites spp., and Lenticulina spp. The presence of Pulsiphonina prima and Valvulineria scorbiculata in Biofacies B suggests an increase in runoff conditions in the basin. Fluctuating trophic conditions prevailed between ∼54–50 Ma. It is evidenced by alternating Biofacies C (endobenthic and chiloguembelinids of eutrophic conditions) and Biofacies D (epibenthic and acarininids of oligotrophic conditions). Biofacies E is dominated by deep-dwelling parasubbotinids, indicating an increase in bathymetry, possibly corresponding to the Early Eocene Climatic Optimum (∼49 Ma).

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