Paleoproterozoic Carbon Isotope Excursion

2015 ◽  
pp. 1831-1831
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotope Excursion

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).

scholarly journals Duration of the Early Toarcian carbon isotope excursion deduced from spectral analysis: Consequence for its possible causes

2008 ◽  
Vol 267 (3-4) ◽  
pp. 666-679 ◽  
Author(s):  
G SUAN ◽  
B PITTET ◽  
I BOUR ◽  
E MATTIOLI ◽  
L DUARTE ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Carbon Isotope ◽  
Carbon Isotope Excursion

scholarly journals Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

2018 ◽  
Vol 37 (1) ◽  
pp. 317-339 ◽  
Author(s):  
Joost Frieling ◽  
Emiel P. Huurdeman ◽  
Charlotte C. M. Rem ◽  
Timme H. Donders ◽  
Jörg Pross ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Climate Models ◽  
Middle Eocene ◽  
Sampling Point ◽  
Drill Core ◽  
Proxy Data ◽  
Southeast Australia ◽  
Carbon Isotope Excursion ◽  
Lithostratigraphic Units ◽  
Pollen Species

Abstract. Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene–Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop sampling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene–Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the dinocyst Apectodinium prior to this negative carbon isotope excursion prohibit a direct correlation of this regional bio-event with the quasi-global Apectodinium acme at the Paleocene–Eocene Thermal Maximum (PETM; 56 Ma). Therefore, the first occurrence of the pollen species Spinizonocolpites prominatus and the dinocyst species Florentinia reichartii are here designated as regional markers for the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further indicates that the early Eocene (∼ 56–51 Ma) sediments are truncated by a ∼ 10 Myr long hiatus overlain by middle Eocene (∼ 40 Ma) strata. These sedimentary archives from southeast Australia may prove key in resolving the model–data discrepancy in this region, and the new stratigraphic data presented here allow for detailed comparisons between paleoclimate records on both sides of the Tasmanian Gateway.

scholarly journals Carbon isotope (δ<sup>13</sup>C) excursions suggest times of major methane release during the last 14 kyr in Fram Strait, the deep-water gateway to the Arctic

2015 ◽  
Vol 11 (4) ◽  
pp. 669-685 ◽  
Author(s):  
C. Consolaro ◽  
T. L. Rasmussen ◽  
G. Panieri ◽  
J. Mienert ◽  
S. Bünz ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Carbon Isotope ◽  
Deep Water ◽  
Planktonic Foraminifera ◽  
Sediment Supply ◽  
The Arctic ◽  
Fram Strait ◽  
The North ◽  
Carbon Isotope Excursion

Abstract. We present results from a sediment core collected from a pockmark field on the Vestnesa Ridge (~ 80° N) in the eastern Fram Strait. This is the only deep-water gateway to the Arctic, and one of the northernmost marine gas hydrate provinces in the world. Eight 14C AMS dates reveal a detailed chronology for the last 14 ka BP. The δ 13C record measured on the benthonic foraminiferal species Cassidulina neoteretis shows two distinct intervals with negative values termed carbon isotope excursion (CIE I and CIE II, respectively). The values were as low as −4.37‰ in CIE I, correlating with the Bølling–Allerød interstadials, and as low as −3.41‰ in CIE II, correlating with the early Holocene. In the Bølling–Allerød interstadials, the planktonic foraminifera also show negative values, probably indicating secondary methane-derived authigenic precipitation affecting the foraminiferal shells. After a cleaning procedure designed to remove authigenic carbonate coatings on benthonic foraminiferal tests from this event, the 13C values are still negative (as low as −2.75‰). The CIE I and CIE II occurred during periods of ocean warming, sea-level rise and increased concentrations of methane (CH4) in the atmosphere. CIEs with similar timing have been reported from other areas in the North Atlantic, suggesting a regional event. The trigger mechanisms for such regional events remain to be determined. We speculate that sea-level rise and seabed loading due to high sediment supply in combination with increased seismic activity as a result of rapid deglaciation may have triggered the escape of significant amounts of methane to the seafloor and the water column above.

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