Genesis of upper proterozoic-cambrian phosphorite deposits of India: isotopic inferences from carbonate fluorapatite, carbonate and organic carbon

Banerjee, D. M.; Schidlowski, Manfred; Arneth, J.-D.

doi:10.1016/0301-9268(86)90024-0

Cited by 56 publications

(21 citation statements)

References 21 publications

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“…A and Table ) have a large range of δ 13 C org values between –32.2 and –13.0‰ (excluding a single analysis at −39.4‰), which yield an average of −18.5‰ (1σ = 4.5‰). This range of δ 13 C org values is slightly larger than previously reported, although 13 C‐enriched organic matter is known to occur in the Jhamarkotra stromatolitic phosphorites (Banerjee et al ., ; Sreenivas et al ., ; Papineau et al ., ).…”

Section: Resultsmentioning

confidence: 99%

“…The δ 13 C org values between –32.1 and –13.0‰ (Fig. ) are also consistent with C‐fixation with the pentose phosphate pathway and similar to previously reported values (Banerjee et al ., ; Sreenivas et al ., ; Papineau et al ., ). Such ranges of δ 13 C org values have been proposed to be consistent with diffusion‐limited CO 2 fixation, growth rates and fluctuating CO 2 concentration (Laws et al ., ).…”

Section: Discussionmentioning

confidence: 99%

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Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India

et al. 2015

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Stromatolites composed of apatite occur in post-Lomagundi-Jatuli successions (late Palaeoproterozoic) and suggest the emergence of novel types of biomineralization at that time. The microscopic and nanoscopic petrology of organic matter in stromatolitic phosphorites might provide insights into the suite of diagenetic processes that formed these types of stromatolites. Correlated geochemical micro-analyses of the organic matter could also yield molecular, elemental and isotopic compositions and thus insights into the role of specific micro-organisms among these communities. Here, we report on the occurrence of nanoscopic disseminated organic matter in the Palaeoproterozoic stromatolitic phosphorite from the Aravalli Supergroup of north-west India. Organic petrography by micro-Raman and Transmission Electron Microscopy demonstrates syngeneity of the organic matter. Total organic carbon contents of these stromatolitic phosphorite columns are between 0.05 and 3.0 wt% and have a large range of δ(13) Corg values with an average of -18.5‰ (1σ = 4.5‰). δ(15) N values of decarbonated rock powders are between -1.2 and +2.7‰. These isotopic compositions point to the important role of biological N2 -fixation and CO2 -fixation by the pentose phosphate pathway consistent with a population of cyanobacteria. Microscopic spheroidal grains of apatite (MSGA) occur in association with calcite microspar in microbial mats from stromatolite columns and with chert in the core of diagenetic apatite rosettes. Organic matter extracted from the stromatolitic phosphorites contains a range of molecular functional group (e.g. carboxylic acid, alcohol, and aliphatic hydrocarbons) as well as nitrile and nitro groups as determined from C- and N-XANES spectra. The presence of organic nitrogen was independently confirmed by a CN(-) peak detected by ToF-SIMS. Nanoscale petrography and geochemistry allow for a refinement of the formation model for the accretion and phototrophic growth of stromatolites. The original microbial biomass is inferred to have been dominated by cyanobacteria, which might be an important contributor of organic matter in shallow-marine phosphorites.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India

et al. 2015

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“…(1999), Sreenivas et al (2001), Banerjee et al (1986) stromatolite growth after the carbon isotope excursion were clearly unfavorable on several continents for at least a short period of time.…”

Section: Implications For the End Of The Carbon Isotope Excursionmentioning

confidence: 99%

Chemostratigraphy of Paleoproterozoic carbonate successions of the Wyoming Craton: tectonic forcing of biogeochemical change?

Bekker

2003

Precambrian Research

143

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“…Ore-grade phosphorite deposits have attracted special interest for their economic potential their relatively rarity in the stratigraphic record, and their value as candidate marker horizons for inter-basinal stratigraphic correlation (e.g. Banerjee et al, 1986Banerjee et al, , 1997. However, uncertainty remains concerning the total number of phosphatic depositional events represented within the Indian stratigraphic succession.…”

Section: Introductionmentioning

confidence: 99%

Age and implications of the phosphatic Birmania Formation, Rajasthan, India

Hughes

Myrow

McKenzie

et al. 2015

Precambrian Research

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a b s t r a c tThe Birmania inlier in western Rajasthan, India, contains important phosphate deposits, the depositional age of which is poorly constrained. Here we provide the first direct age constraints for the phosphatebearing Birmania Formation using a combination of paleontological and detrital zircon U-Pb data. The occurrence of the multicellular algal fossil Wengania exquisita in phosphatic chert of the Birmania Formation suggest that it was deposited during the Ediacaran. Detrital zircon age distributions contain prominent populations of 1.7-1.9 Ga grains, with subordinate younger grains that range from 650 to 980 Ma. The distribution broadly resembles those from Neoproterozoic strata from both cratonic and Himalayan India but, like zircon age distributions from the Marwar Group, lacks 1.0-1.2 Ga grains, which may suggest that both areas shared similar local sources. The lack of zircon grains younger than ∼650 Ma is consistent with an Ediacaran depositional age because almost all Cambrian or younger strata from India have yielded Cambrian or latest Neoproterozoic age grains. These findings raise the possibility of a previously unrecognized late Neoproterozoic episode of phosphogenesis on the India craton. The presence of Wengania exquisita further supports strong palaeogeographic affinity between the India and South China during the Neoproterozoic and Cambrian.

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Genesis of upper proterozoic-cambrian phosphorite deposits of India: isotopic inferences from carbonate fluorapatite, carbonate and organic carbon

Cited by 56 publications

References 21 publications

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India

Chemostratigraphy of Paleoproterozoic carbonate successions of the Wyoming Craton: tectonic forcing of biogeochemical change?

Age and implications of the phosphatic Birmania Formation, Rajasthan, India

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