A study of the organic matter in Tunisian phosphates series: Relevance to phosphorite genesis in the Gafsa Basin (Tunisia)

Belayouni, Habib; Slansky, Maurice; Trichet, Jean

doi:10.1016/0146-6380(90)90184-2

Cited by 21 publications

(10 citation statements)

References 56 publications

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“…This OM is directly related to phosphorite ore used for the phosphate treatment. Belayouni and Trichet [ 6 ] showed that the phosphorites from the Gafsa basin are relatively rich in OM [ 7 ]. During the pre-treatment, the phosphorite ore is enriched in phosphorus by several crushing and sieving steps [ 81 ].…”

Section: Discussionmentioning

confidence: 99%

Impact of industrial phosphate waste discharge on the marine environment in the Gulf of Gabes (Tunisia)

et al. 2018

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The marine environment in the Gulf of Gabes (southern Tunisia) is severely impacted by phosphate industries. Nowadays, three localities, Sfax, Skhira and Gabes produce phosphoric acid along the coasts of this Gulf and generate a large amount of phosphogypsum as a waste product. The Gabes phosphate industry is the major cause of pollution in the Gulf because most of the waste is directly discharged into the sea without preliminary treatment. This study investigates the marine environment in the proximity of the phosphate industries of Gabes and the coastal marine environment on the eastern coast of Djerba, without phosphate industry. This site can be considered as "pristine" and enables a direct comparison between polluted and “clean” adjacent areas.Phosphorous, by sequential extractions (SEDEX), Rock-Eval, C, H, N elemental analysis, and stable carbon isotope composition of sedimentary organic matter, X-ray diffraction (qualitative and quantitative analysis) were measured on sediments. Temperature, pH and dissolved oxygen were measured on the water close to the sea floor of each station to estimate environmental conditions. These analyses are coupled with video surveys of the sea floor. This study reveals clear differentiations in pollution and eutrophication in the investigated areas.

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Section: Discussionmentioning

confidence: 99%

Impact of industrial phosphate waste discharge on the marine environment in the Gulf of Gabes (Tunisia)

et al. 2018

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“…Two opposite hypotheses have been proposed (Amieux 1980;Demaison and Moore 1980;Herbert and Fischer 1986;Belayouni et al 1990Belayouni et al , 2003Fiet 1998;Ettensohn 2001;Varentsov et al 2003;Schieber 2004 and references therein): bottom-water anoxia versus high organic productivity in shallow water. The first case implies long time periods, while the second case involves cyclic phases but not longer in time.…”

Section: Origin Of Black Shalesmentioning

confidence: 95%

“…The Menilite black shales are also of a great significance as organic-rich marker beds within the Oligocene siliciclastic succession, because precise indications, such as the physico-chemical conditions of the depositional environment, the origin of the sedimentary materials and the geological basin evolution, could be deduced from the geochemical study of their organic content (Hunt 1979;Demaison and Moore 1980;Tissot and Welte 1984;Belayouni et al 1990;Curtis et al 2004).…”

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confidence: 99%

Stratigraphic and geochemical study of the organic-rich black shales in the Tarcău Nappe of the Moldavidian Domain (Carpathian Chain, Romania)

Belayouni

Staso

Guerrera

et al. 2007

Int J Earth Sci (Geol Rundsch)

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An integrated stratigraphic analysis has been made of the Tarcȃu Nappe (Moldavidian Domain, Eastern Romanian Carpathians), coupled with a geochemical study of organic-rich beds. Two Main Sequence Boundaries (Early Oligocene and near to the Oligocene-Aquitanian boundary, respectively) divide the sedimentary record into three depositional sequences. The sedimentation occurred in the central area of a basin supplied by different and opposite sources. The high amount of siliciclastics at the beginning of the Miocene marks the activation of the ''foredeep stage''. The successions studied are younger than previously thought and they more accurately date the deformation of the different Miocene phases affecting the Moldavidian Basin. The intervals with black shales identified are related to two main separate anoxic episodes with an age not older than Late Rupelian and not before Late Chattian. The most important organic-rich beds correspond to the Lower Menilites, Bituminous Marls and Lower Dysodilic Shales Members (Interval 2). These constitute a good potential source rock for petroleum, with homogeneous Type II oil-prone organic matter, highly lipidic and thermally immature. The deposition of black shales has been interpreted as occurring within a deep, periodically isolated and tectonically controlled basin.

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“…There are other records of hydrocarbons in phosphate‐rich strata. For example, Belayouni et al. (1990) describe peloidal, francolite‐rich phosphorites interbedded with shales and limestones in the Late Cretaceous–Palaeogene Gafsa Basin of Tunisia.…”

Section: Discussionmentioning

confidence: 99%

Microtextures, geochemistry and geochronology of authigenic xenotime: constraining the cementation history of a Palaeoproterozoic metasedimentary sequence

et al. 2005

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An ≈ 26 m thick unit of phosphatic sandstone and black shale (the Phosphatic Unit) in the Palaeoproterozoic Mount Barren Group of south‐western Australia contains abundant authigenic xenotime crystals showing well‐preserved diagenetic textures. Despite extensive regional deformation and thermal metamorphism, the peak of which occurred at ≈ 1205 Ma, the Phosphatic Unit was preserved as a low‐strain envelope because of its pre‐compaction carbonate and phosphate cementation. In situ U–Pb geochronology of xenotime reveals four discrete age populations at 1693 ± 4, 1645 ± 3, 1578 ± 10 and 1481 ± 21 Ma. When integrated with petrography, the age data place a timeframe on: (i) sediment deposition; (ii) phosphogenesis; (iii) diagenetic cement infilling; (iv) diagenetic pyrite formation; (v) secondary porosity generation; (vi) hydrocarbon migration; (vii) burial compaction; and (viii) hydrothermal alteration, up until peak thermal metamorphism. Xenotime growth at ≈ 1693 Ma occurred prior to compaction, whereas xenotime growth at ≈ 1645 Ma occurred during burial. Xenotime growth at ≈ 1580 Ma and at ≈ 1480 Ma appears to be the far‐field record of thermotectonic events associated with intracontinental extension and magmatism recorded elsewhere in Australia. Geochemical analysis, integrated with geochronology, shows a systematic increase in MREE/HREE in xenotime crystals with decreasing age and with increasing stratigraphic depth. Coupled with a decrease in xenotime abundance and age with depth, it suggests that: (i) the main focus of porosity infilling was at the top of the Phosphatic Unit and progressed downwards over the > 200 Myr period of porosity infilling, and (ii) the changes in xenotime REE chemistry may be due to an influx of MREE from increasing amounts of dissolved apatite or changes, with respect to REE solubility, in the physiochemical nature of the fluids with burial depth.

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A study of the organic matter in Tunisian phosphates series: Relevance to phosphorite genesis in the Gafsa Basin (Tunisia)

Cited by 21 publications

References 56 publications

Impact of industrial phosphate waste discharge on the marine environment in the Gulf of Gabes (Tunisia)

Impact of industrial phosphate waste discharge on the marine environment in the Gulf of Gabes (Tunisia)

Stratigraphic and geochemical study of the organic-rich black shales in the Tarcău Nappe of the Moldavidian Domain (Carpathian Chain, Romania)

Microtextures, geochemistry and geochronology of authigenic xenotime: constraining the cementation history of a Palaeoproterozoic metasedimentary sequence

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