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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.

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(a) Trough cross-stratified sandstone facies within Barakar Formation, Khudia Nala, Ranjiganj Basin. Length of the hammer is 30.5 cm. (b) Amalgamated sandstone beds showing multiple sets of planar and trough cross-stratification, Barakar Formation, Kudaposi Nala, Talchir Basin. Length of the pen is 14.6 cm.
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fig4: (a) Trough cross-stratified sandstone facies within Barakar Formation, Khudia Nala, Ranjiganj Basin. Length of the hammer is 30.5 cm. (b) Amalgamated sandstone beds showing multiple sets of planar and trough cross-stratification, Barakar Formation, Kudaposi Nala, Talchir Basin. Length of the pen is 14.6 cm.

Mentions: The studied rocks preserved in both the Kudaposi Nala section, Talchir Basin, and the Khudia Nala section, Raniganj Basin (Figure 1), represent part of the upper Barakar sedimentary succession (Figures 2 and 3). The upper Barakar sedimentary successions of both the Damodar Valley and the Mahanadi Valley have been assigned the age of Kungurian (post-Artinskian) with an approximate time frame of 278–271 Ma [11]. The studied rocks are characterized by thick-bedded (1–2.5 m thickness), coarse-grained, trough cross-stratified to plane-laminated sandstone facies (Figures 4(a) and 4(b)), overlain by cm thin sandstone-siltstone-claystone alternations facies (Figures 5(a) and 5(b)). Thickness of the sandstone-siltstone-claystone alternation facies varies from 1.5 m to 4.3 m. The sandstone beds within this facies are characterized by wave ripples and wave-modified ripples, tidal bundles represented by mud-draped foresets, climbing ripples, flaser beddings, bidirectional ripples, mutually opposite cross-strata sets, vertical and lateral accretion of cross-strata sets with prominent reactivation surfaces, and so forth. Each sandstone bed grades upward to a siltstone/claystone. The claystone beds are occasionally very thick (thickness 1–1.8 m) and are characterized by abundant Chondrites isp. on the bedding plane. The sandstone/siltstone-claystone heteroliths that underlie and overlie such thick claystone beds are often characterized by sparse to abundant trace fossil associations, dominantly Planolites isp., Thalassinoides isp., and Paleophycus isp., along with abundant plant fossils. The successions show coarsening upward trend with gradual increase in the deposition of sandstone towards top, and finally overlain by a thick-bedded, trough cross-stratified, coarse-grained sandstone facies.


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

Bhattacharya B, Banerjee S - ScientificWorldJournal (2014)

(a) Trough cross-stratified sandstone facies within Barakar Formation, Khudia Nala, Ranjiganj Basin. Length of the hammer is 30.5 cm. (b) Amalgamated sandstone beds showing multiple sets of planar and trough cross-stratification, Barakar Formation, Kudaposi Nala, Talchir Basin. Length of the pen is 14.6 cm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig4: (a) Trough cross-stratified sandstone facies within Barakar Formation, Khudia Nala, Ranjiganj Basin. Length of the hammer is 30.5 cm. (b) Amalgamated sandstone beds showing multiple sets of planar and trough cross-stratification, Barakar Formation, Kudaposi Nala, Talchir Basin. Length of the pen is 14.6 cm.
Mentions: The studied rocks preserved in both the Kudaposi Nala section, Talchir Basin, and the Khudia Nala section, Raniganj Basin (Figure 1), represent part of the upper Barakar sedimentary succession (Figures 2 and 3). The upper Barakar sedimentary successions of both the Damodar Valley and the Mahanadi Valley have been assigned the age of Kungurian (post-Artinskian) with an approximate time frame of 278–271 Ma [11]. The studied rocks are characterized by thick-bedded (1–2.5 m thickness), coarse-grained, trough cross-stratified to plane-laminated sandstone facies (Figures 4(a) and 4(b)), overlain by cm thin sandstone-siltstone-claystone alternations facies (Figures 5(a) and 5(b)). Thickness of the sandstone-siltstone-claystone alternation facies varies from 1.5 m to 4.3 m. The sandstone beds within this facies are characterized by wave ripples and wave-modified ripples, tidal bundles represented by mud-draped foresets, climbing ripples, flaser beddings, bidirectional ripples, mutually opposite cross-strata sets, vertical and lateral accretion of cross-strata sets with prominent reactivation surfaces, and so forth. Each sandstone bed grades upward to a siltstone/claystone. The claystone beds are occasionally very thick (thickness 1–1.8 m) and are characterized by abundant Chondrites isp. on the bedding plane. The sandstone/siltstone-claystone heteroliths that underlie and overlie such thick claystone beds are often characterized by sparse to abundant trace fossil associations, dominantly Planolites isp., Thalassinoides isp., and Paleophycus isp., along with abundant plant fossils. The successions show coarsening upward trend with gradual increase in the deposition of sandstone towards top, and finally overlain by a thick-bedded, trough cross-stratified, coarse-grained sandstone facies.

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