Global and local factors behind the authigenesis of Fe-silicates (Glauconite/Chamosite) in Miocene strata of Northern Tunisia

Tounekti, Abdelbasset; Boukhalfa, Kamel; Choudhury, Tathagata Roy; Soussi, Mohamed; Banerjee, Santanu

doi:10.1016/j.jafrearsci.2021.104342

Cited by 13 publications

(10 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Petrographic characteristics suggest authigenic glauconite formation. Preservation of delicate radial cracks within glauconite pellets confirms in situ formation [1,5,6,19,40,41]. The poorly sorted, euhedral quartz, and lithic fragments (Figure 3C-F) suggest a volcanic source for the detrital sediment [42].…”

Section: Petrography Of Glauconitementioning

confidence: 67%

“…Absence of goethite and/or pyrite suggest similar sub-oxic condition prevailed throughout the glauconite formation [19]. The enhanced supply of organic matter from the continent might have facilitated the sub-oxic depositional condition where the formation of glauconite through incorporation of K and Fe by the substrate [7,18,19,41,43]. The high Al 2 O 3 content of the Giral glauconite corresponding to the tetrahedral Al 3+ suggests a high aluminous substrate for these glauconites [19].…”

Section: Unique Chemical Composition Of Giral Glauconite and Origin Of Glauconitementioning

confidence: 99%

See 1 more Smart Citation

Paleoenvironmental Conditions during the Paleocene–Eocene Transition Imprinted within the Glauconitic Giral Member of the Barmer Basin, India

et al. 2021

Self Cite

View full text Add to dashboard Cite

The roughly 6 m thick limestone–green shale alternation within the lignite-bearing Giral Member of the Barmer Basin corresponds to a marine flooding event immediately after the Paleocene–Eocene transition. A detailed characterization of the glauconite using Electron Probe Micro Analyzer (EPMA), X-Ray Diffraction (XRD), Mössbauer and Field Emission Gun-Scanning Electron Microscope (FEG-SEM) reveals its origin in the backdrop of prevailing warm climatic conditions. The glauconite pellets vary from fine silt-sized to coarse sand-sized pellets, often reaching ~60% of the rock by volume. Mineralogical investigation reveals a ‘nascent’ to ‘slightly evolved’ character of the marginal marine-originated glauconite showing considerable interstratification. The chemical composition of the glauconite is unusual with a high Al2O3 (>10 wt%) and moderately high Fe2O3(total) contents (>15 wt%). While the K2O content of these glauconites is low, the interlayer sites are atypically rich in Na2O, frequently occupying ~33% of the total interlayer sites. The Mössbauer spectrum indicates 10% of the total iron is in ferrous form. High tetrahedral Al3+ of these glauconites suggests a high-alumina substrate that transformed to glauconite by octahedral Al-for-Fe substitution followed by the addition of K into the interlayer structure. The unusually high Na2O suggests the possibility of a soda-rich pore water formed by the dissolution of alkaline volcanic minerals. The Giral glauconite formation could have been a part of the major contributors in the Fe-sequestration cycle in the Early Eocene shelves. Warm climate during the Early Eocene time favored the glauconitization because of the enhanced supply of Fe, Al, and Si and proliferation of an oxygen-depleted depositional environment.

show abstract

Section: Petrography Of Glauconitementioning

confidence: 67%

Section: Unique Chemical Composition Of Giral Glauconite and Origin Of Glauconitementioning

confidence: 99%

Paleoenvironmental Conditions during the Paleocene–Eocene Transition Imprinted within the Glauconitic Giral Member of the Barmer Basin, India

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…This form of chamosite is interpreted to be originally generated by aggregation near the sediment–water interface in low‐energy environments (Todd et al ., 2019). Similar environments may have also facilitated chamosite formation within the pores of bioclasts (Tounekti et al ., 2021).…”

Section: Discussionmentioning

confidence: 99%

“…3F), the different forms of chamositic grains originally grew under different hydrodynamic conditions at various seafloor depths (from above fair‐weather wave base to below storm wave base). Therefore, their co‐occurrence in the ironstones must result from reworking and transportation, most probably induced by storms during final settling (Todd et al ., 2019; Tounekti et al ., 2021). Supporting this storm‐reworking interpretation is the graded bedding associated with the ironstones (Fig.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Microbe‐mediated, marine authigenic formation of ooidal chamosite: Insights from upper Ordovician carbonates of the South‐Western Yangtze platform (China)

et al. 2023

View full text Add to dashboard Cite

Chamosite is a common marine authigenic mineral and microbial involvement has been often assumed during its formation. However, the fossil record of such microbial activity is ambiguous. Chamosite oolitic ironstones widely occur in the Upper Ordovician of the Yangtze Platform, but their origin remains unclear. In this study, detailed sedimentological and mineralogical investigations on ironstones from the Haima section (south-western Yangtze Platform) helped unravel the critical role of cyanobacterial activity during marine chamosite authigenesis. Stratigraphically, deposition of the Haima oolitic ironstones corresponded with an early Katian transgression, temporally equivalent to many other early Palaeozoic counterparts worldwide. Petrographic observations revealed that different chamosite forms (ooids, peloids and matrix) all developed in close association with calcified cyanobacteria, suggesting that cyanobacteria-involved chamosite formation existed across a wide range of hydrodynamic conditions from above fairweather wave base to below storm wave base. Further mineralogical characterization (backscatter imaging and electron-microprobe analyses) at singlegrain scale revealed clear mineral zonation from the matrix (dispersed iron oxide and microquartz) through the calcified cyanobacterial sheaths (dispersed chamosite) to the ooid (chamosite). This zonation is best explained by cyanobacterial microbial mats that created benthic reducing and high-pH conditions. These conditions drove near-seafloor, dispersed iron oxide and microquartz (primary precipitates formed in oxic seawater) to form chamosite. The authigenic chamosite, originally dispersed within and surrounding the microbial mats, could be reworked to develop other chamositic grains. It is proposed here that the early Katian transgression was responsible for the chamosite-oolitic-ironstone development. The marine transgression submerged earlier-exposed lands and likely supplied Fe-Al-rich colloidal materials to an open marine setting for the chamosite authigenesis. Moreover, transgression likely triggered upwelling, delivered ferruginous deeper water as an extra Fe source and provided nutrients for the cyanobacterial microbial-mat development, which was essential for the widespread chamosite authigenesis across the south-western Yangtze Platform.

show abstract

The Geochemical Affinity of Paleogene Glauconites in Paleo-Tethyan Deposits of India

Choudhury¹,

Banerjee²,

Khanolkar³

2022

Geochemical Treasures and Petrogenetic Processes

View full text Add to dashboard Cite

Global and local factors behind the authigenesis of Fe-silicates (Glauconite/Chamosite) in Miocene strata of Northern Tunisia

Cited by 13 publications

References 79 publications

Paleoenvironmental Conditions during the Paleocene–Eocene Transition Imprinted within the Glauconitic Giral Member of the Barmer Basin, India

Paleoenvironmental Conditions during the Paleocene–Eocene Transition Imprinted within the Glauconitic Giral Member of the Barmer Basin, India

Microbe‐mediated, marine authigenic formation of ooidal chamosite: Insights from upper Ordovician carbonates of the South‐Western Yangtze platform (China)

The Geochemical Affinity of Paleogene Glauconites in Paleo-Tethyan Deposits of India

Contact Info

Product

Resources

About