Trace fossils from Talchir carbonate concretions, Giridih basin, Jharkhand

Das, Saubhik; Tripathi, Mahesh Kumar

doi:10.1007/s12040-009-0009-6

Cited by 8 publications

(3 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In many calcium carbonate concretions, intact three-dimensional (3-day) fossils, undeformed sedimentary textures, and card-house-like clay structures have been found. This proves the capacity of carbonate concretions to resist compaction (Lash and Blood, 2004;Das and Tripathi, 2009). Authigenic carbonates in concretionary bodies can form an armor that blocks all types of external fluids during encapsulation, minimizing the chemical reactions of materials within the concretions (Raiswell and Fisher, 2000).…”

Section: Introductionmentioning

confidence: 81%

Preservation of molecular fossils in carbonate concretions in cretaceous shales in the songliao basin, northeast China

Lin

Fang²,

Xu³

2023

Front. Earth Sci.

View full text Add to dashboard Cite

Paleoenvironmental information is better preserved in carbonate concretions. In this study, carbonate concretions in the Cretaceous Nenjiang shale, Songliao Basin, were examined to determine whether molecular fossils reflective of the paleoenvironment were better preserved at these sites. Organic and inorganic geochemical characteristics of the concretions and surrounding rocks were analyzed using a series of techniques, including SEM, LA-ICP-MS, GC-MS-MS, and GC-IRMS. The concretions are composed of high content microcrystalline dolomite. The δ13Ccarb and δ18Ocarb values of the concretionary dolomite were significantly higher than those of the surrounding rocks. The dolomite show enrichment in the LREEs and have a negative Eu anomaly. The concretion biomarkers showed distribution characteristics similar to those of surrounding rocks. This suggested that the molecular fossils preserved in concretions were mainly inherited from surrounding rocks. However, the concretions contained more C27 sterane and hopanes, with the hopane/sterane ratio being significantly higher than that of surrounding rocks (1.49 v. 0.86). Moreover, the relative content of 2-methylhopane was 2.4–6.6 times that of the surrounding rocks. This indicated changes in the biological equilibrium of source organisms within and outside the concretions. It was possible that the unstable organic matter at the core increased the bacterial concentration and activity inside the concretions. Both the hydrogen index and biomarker-derived indicators implied that the transformation of organic matter in concretions was minimized when compared with their host rock. The isotope δ13C16-30 was 1‰–3‰ more prevalent in individual N-alkane hydrocarbons in the concretions than in surrounding rocks, likely owing to differences in lithology, bacterial action, and degree of weathering. The study concluded that carbonate concretions could preserve molecular fossils better than the surrounding rocks, and the in-depth organic geochemical analysis of concretions could provide a valuable reference for research into early life forms.

show abstract

Section: Introductionmentioning

confidence: 81%

Preservation of molecular fossils in carbonate concretions in cretaceous shales in the songliao basin, northeast China

Lin

Fang²,

Xu³

2023

Front. Earth Sci.

View full text Add to dashboard Cite

show abstract

“…High silica source rocks [19][20] tend to contain higher concentrations of REE, Th, Hf and Ba, lower concentration of Co, Fe, Sc and Cr, and more negative Eu anomalies than the low silica source rocks [17][18] High SiO containing rock samples of Dudhi Nala has higher concentration of Ba (1047ppm), Th (22ppm), Zr (256ppm), Sr(312ppm) and Pb (65ppm). And High Fe 2 O 3 containing rock samples of Bokaro river has higher concentration of Sc (39ppm) and Zn (90ppm).…”

Section: X-ray Diffraction Studymentioning

confidence: 99%

Quantitative Mineralogical Analysis and Study of Morphology and Thermal Characteristics of Rock Samples of Dudhi Nala and Bokaro River.

Mahato,

Srivastava

2023

Orient. J. Chem

View full text Add to dashboard Cite

Beds of Talchir formation are well exposed in the western part of the Bokaro coalfields (Dudhi Nala) which comprises tillite, conglomerates, sandstones, with dropstones and turbidite sequences comprising siltstones and shales. This work presents the study of glacigenic Talchir sediments of Dudhi Nala section and sediments of Bokaro river. The morphology, major oxides, trace elements, Rare Earth elements and minerals found in these sediments are of great geological importance. The minerals present in these samples have been also investigated. The samples collected from Dudhi Nala are enriched in SiO2 (66-68 wt % compared to 25-60 wt % in the samples of Bokaro river). In contrast to SiO2, Fe2O3 is dominant in the Bokaro river samples. Dudhi Nala samples are rich in trace elements like Ba (1047 ppm), Rb ( 219 ppm), Sr (312 ppm), Zr ( 256 ppm) and Pb (65 ppm), where as Bokaro river samples dominates in Cr (140 ppm), Sc (39 ppm), V (117 ppm) and Zn (90 ppm). FESEM/ EDX analysis was done to study the morphological characteristics and elemental composition were analysed by FESEM/EDX. Thermal characteristics of the samples were studied by TGA/DSC. Further, XRD analysis confirmed that Calcite and feldspar are the common minerals present in the samples of the both the study areas.

show abstract

“…Most studies of shale-hosted carbonate concretions have focused mainly on the organo-diagenetic processes occurring in marine environments (Raiswell and Fisher, 2000;Plet et al, 2016;Gaines and Vorhies, 2016). Relatively little attention has been given to the growth process of carbonate concretions in fresh-water lake sediments (Das and Tripathi, 2009).…”

mentioning

confidence: 99%

Origin of Phosphate‐bearing Carbonate Concretions in the Upper Triassic Lacustrine Black Shales of the Southern Ordos Basin, China

Zhang

Liu

Zhang

et al. 2021

Acta Geologica Sinica (Eng)

View full text Add to dashboard Cite

Carbonate concretions are conspicuous in organic‐rich shales and are generally related to decomposition of organic matter. The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southern Ordos Basin host abundant carbonate concretions, which provide a unique record of depositional and early diagenetic conditions of the paleo‐lake sediments. However, little attention has been given to the genesis and growth processes of the concretions in these lacustrine petroleum source rocks. New petrographic observations and geochemical analysis show that the concretions are composed of calcite, phosphate fossil fragments, K‐NH4‐feldspar, quartz, bitumen, and minor Fedolomite. Phosphate minerals, mainly carbonate fluorapatite (CFA), show pervasive replacement by calcite, most of which contains phosphorus, ranging in concentration from 0.26 to 2.35 wt%. This suggests that the phosphate minerals are the precursors for concretion growth. Positive δ13C (+5.6 to +12.4 ‰ V‐PDB) signatures and the absence of pyrite indicate that microbial methanogenesis was the dominant driver for concretion growth, rather than bacterial sulfate reduction. Quartz, bitumen, and Fe‐dolomite are the last cements that occurred, at deep burial depths and high temperatures. The formation of phosphate minerals might have been induced by upwelling of phosphate‐enriched deep water in the Late Triassic paleolake, which promoted phytoplankton blooms and further enrichment of organic matter. Extremely slow sedimentation rates of fine‐grained detrital minerals, relative to dead organism accumulation, led to the high permeabilities of the organic‐rich sediments and rapid concretion growth during shallow burial. The close association of phosphate‐bearing carbonate concretions and organic‐rich shales reflects that upwelling played a critical role in the formation of the high‐quality petroleum source rocks in the Triassic paleo‐Ordos lake.

show abstract

Trace fossils from Talchir carbonate concretions, Giridih basin, Jharkhand

Cited by 8 publications

References 27 publications

Preservation of molecular fossils in carbonate concretions in cretaceous shales in the songliao basin, northeast China

Preservation of molecular fossils in carbonate concretions in cretaceous shales in the songliao basin, northeast China

Quantitative Mineralogical Analysis and Study of Morphology and Thermal Characteristics of Rock Samples of Dudhi Nala and Bokaro River.

Origin of Phosphate‐bearing Carbonate Concretions in the Upper Triassic Lacustrine Black Shales of the Southern Ordos Basin, China

Contact Info

Product

Resources

About