Limits...
Chondrites isp. indicating late paleozoic atmospheric anoxia in Eastern Peninsular India.

Bhattacharya B, Banerjee S - ScientificWorldJournal (2014)

Bottom Line: Rhythmic sandstone-mudstone-coal succession of the Barakar Formation (early Permian) manifests a transition from lower braided-fluvial to upper tide-wave influenced, estuarine setting.Monospecific assemblage of marine trace fossil Chondrites isp. in contemporaneous claystone beds in the upper Barakar succession from two Gondwana basins (namely, the Raniganj Basin and the Talchir Basin) in eastern peninsular India signifies predominant marine incursion during end early Permian.Such anoxia is interpreted as intermittent falls in oxygen level in an overall decreasing atmospheric oxygenation within the late Paleozoic global oxygen-carbon dioxide fluctuations.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India.

ABSTRACT
Rhythmic sandstone-mudstone-coal succession of the Barakar Formation (early Permian) manifests a transition from lower braided-fluvial to upper tide-wave influenced, estuarine setting. Monospecific assemblage of marine trace fossil Chondrites isp. in contemporaneous claystone beds in the upper Barakar succession from two Gondwana basins (namely, the Raniganj Basin and the Talchir Basin) in eastern peninsular India signifies predominant marine incursion during end early Permian. Monospecific Chondrites ichnoassemblage in different sedimentary horizons in geographically wide apart (~400 km) areas demarcates multiple short-spanned phases of anoxia in eastern India. Such anoxia is interpreted as intermittent falls in oxygen level in an overall decreasing atmospheric oxygenation within the late Paleozoic global oxygen-carbon dioxide fluctuations.

Show MeSH

Related in: MedlinePlus

Plot showing concentration of O2 and CO2 in the atmosphere during the Phanerozoic time (modified after 31, 32). Note the O2 and CO2 concentrations during the upper Barakar sedimentation (278–271 Ma).
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3926327&req=5

fig7: Plot showing concentration of O2 and CO2 in the atmosphere during the Phanerozoic time (modified after 31, 32). Note the O2 and CO2 concentrations during the upper Barakar sedimentation (278–271 Ma).

Mentions: Atmospheric oxygen levels show wide fluctuations during the late Paleozoic time. The oxygen level reached a maximum of 35% at the end Carboniferous causing enhancement of respiration and gigantism in organisms. This was followed by a significant drop to 15% at the end Permian leading to mass extinction at the Permo-Triassic boundary. Concomitantly, the carbon dioxide content was raised through the Devonian and Carboniferous, followed by an approximately tenfold reduction during the middle to late Paleozoic time [28, 29]. During Permian, extensive coal deposition resulted from lesser extent of decomposition of terrestrial plant ecosystems and increased carbon fixation by carbon-reducing organisms. Such disequilibrium between free and stored carbon concentration, extensive oxygen release due to post-Silurian terrestrialization by plants together with changes in continental weathering, organic carbon deposition, and biotic decomposition dramatically modified the atmospheric carbon dioxide and oxygen levels [28, 30]. The time frame 278–271 Ma (upper Barakar sedimentation) demarcates a steady fall in the atmospheric oxygen level (~32–25%) accompanied by a very slow-rising carbon dioxide concentration (<0.1%) in global scale (Figure 7) [31, 32]. Record of anoxia demarcated by the Chondrites ichnoassemblage, followed by Planolites-Thalassinoides ichnoassemblages in the overlying and the underlying successions, within the upper Barakar succession in eastern India can be correlated with intermittent drops in oxygen level within a steady phase of decreasing oxygenation within an overall fluctuating atmospheric condition during the early Permian period.


Chondrites isp. indicating late paleozoic atmospheric anoxia in Eastern Peninsular India.

Bhattacharya B, Banerjee S - ScientificWorldJournal (2014)

Plot showing concentration of O2 and CO2 in the atmosphere during the Phanerozoic time (modified after 31, 32). Note the O2 and CO2 concentrations during the upper Barakar sedimentation (278–271 Ma).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3926327&req=5

fig7: Plot showing concentration of O2 and CO2 in the atmosphere during the Phanerozoic time (modified after 31, 32). Note the O2 and CO2 concentrations during the upper Barakar sedimentation (278–271 Ma).
Mentions: Atmospheric oxygen levels show wide fluctuations during the late Paleozoic time. The oxygen level reached a maximum of 35% at the end Carboniferous causing enhancement of respiration and gigantism in organisms. This was followed by a significant drop to 15% at the end Permian leading to mass extinction at the Permo-Triassic boundary. Concomitantly, the carbon dioxide content was raised through the Devonian and Carboniferous, followed by an approximately tenfold reduction during the middle to late Paleozoic time [28, 29]. During Permian, extensive coal deposition resulted from lesser extent of decomposition of terrestrial plant ecosystems and increased carbon fixation by carbon-reducing organisms. Such disequilibrium between free and stored carbon concentration, extensive oxygen release due to post-Silurian terrestrialization by plants together with changes in continental weathering, organic carbon deposition, and biotic decomposition dramatically modified the atmospheric carbon dioxide and oxygen levels [28, 30]. The time frame 278–271 Ma (upper Barakar sedimentation) demarcates a steady fall in the atmospheric oxygen level (~32–25%) accompanied by a very slow-rising carbon dioxide concentration (<0.1%) in global scale (Figure 7) [31, 32]. Record of anoxia demarcated by the Chondrites ichnoassemblage, followed by Planolites-Thalassinoides ichnoassemblages in the overlying and the underlying successions, within the upper Barakar succession in eastern India can be correlated with intermittent drops in oxygen level within a steady phase of decreasing oxygenation within an overall fluctuating atmospheric condition during the early Permian period.

Bottom Line: Rhythmic sandstone-mudstone-coal succession of the Barakar Formation (early Permian) manifests a transition from lower braided-fluvial to upper tide-wave influenced, estuarine setting.Monospecific assemblage of marine trace fossil Chondrites isp. in contemporaneous claystone beds in the upper Barakar succession from two Gondwana basins (namely, the Raniganj Basin and the Talchir Basin) in eastern peninsular India signifies predominant marine incursion during end early Permian.Such anoxia is interpreted as intermittent falls in oxygen level in an overall decreasing atmospheric oxygenation within the late Paleozoic global oxygen-carbon dioxide fluctuations.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India.

ABSTRACT
Rhythmic sandstone-mudstone-coal succession of the Barakar Formation (early Permian) manifests a transition from lower braided-fluvial to upper tide-wave influenced, estuarine setting. Monospecific assemblage of marine trace fossil Chondrites isp. in contemporaneous claystone beds in the upper Barakar succession from two Gondwana basins (namely, the Raniganj Basin and the Talchir Basin) in eastern peninsular India signifies predominant marine incursion during end early Permian. Monospecific Chondrites ichnoassemblage in different sedimentary horizons in geographically wide apart (~400 km) areas demarcates multiple short-spanned phases of anoxia in eastern India. Such anoxia is interpreted as intermittent falls in oxygen level in an overall decreasing atmospheric oxygenation within the late Paleozoic global oxygen-carbon dioxide fluctuations.

Show MeSH
Related in: MedlinePlus