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Geological and Mineralogical Analysis of Phosphorites in the Jebel Dhyr Syncline, Eastern Algerian Atlas Cover

Geological and Mineralogical Analysis of Phosphorites in the Jebel Dhyr Syncline, Eastern Algerian Atlas

Mineralogia
Volume 54 (2023): Issue 1 (January 2023)
By: Salim Boulemia,  Riheb Hadji,  Salah Bouhlal,  Younes Hamed,  Houda Besser and  Kaouther Ncibi  
Open Access
|Dec 2023

Figures & Tables

Figure 1.

Geographic location of the study area.
Geographic location of the study area.

Figure 2.

A: Simplified geological map of the Jebel Dhyr syncline; B: Lithostratigraphic log of Jebel Dhyr. [Legend of the geological map: 1= Holocene: Current and recent alluvium, scree slopes, piedmont accumulation, molasses. 2= Plio-Quaternary: Pebbles (sandstone and conglomerates) and marls. 3= Upper Lutetian: Marls, clays and conglomerates. 4= Ypresian, Lower Lutetian: Limestone with flint and marl-limestone, sometimes with gypsum. 5= Paleocene-Maastrichtian: Marl and marl-limestone. 6= Campanian, Maastrichtian: Marly at the base and varied limestone (oolitic, organogenic, flint) at the top. 7= Coniacian and Santonian: Limestones. 8= Turonian: Limestones and marls. 9= Cenomanian: Yellow limestone, marl and gypsum and dolomites. 10= Samples. 11= Streams. 12= Faults].
A: Simplified geological map of the Jebel Dhyr syncline; B: Lithostratigraphic log of Jebel Dhyr. [Legend of the geological map: 1= Holocene: Current and recent alluvium, scree slopes, piedmont accumulation, molasses. 2= Plio-Quaternary: Pebbles (sandstone and conglomerates) and marls. 3= Upper Lutetian: Marls, clays and conglomerates. 4= Ypresian, Lower Lutetian: Limestone with flint and marl-limestone, sometimes with gypsum. 5= Paleocene-Maastrichtian: Marl and marl-limestone. 6= Campanian, Maastrichtian: Marly at the base and varied limestone (oolitic, organogenic, flint) at the top. 7= Coniacian and Santonian: Limestones. 8= Turonian: Limestones and marls. 9= Cenomanian: Yellow limestone, marl and gypsum and dolomites. 10= Samples. 11= Streams. 12= Faults].

Figure 3.

Panoramic view of the flanks of the Jebel Dhyr syncline; A: extreme southeast flank, B: southwest flank; C: The outcrops of the ten phosphate levels (Phosphorites and Marly limestone phosphates) sampled from Jebel Dhyr Syncline.
Panoramic view of the flanks of the Jebel Dhyr syncline; A: extreme southeast flank, B: southwest flank; C: The outcrops of the ten phosphate levels (Phosphorites and Marly limestone phosphates) sampled from Jebel Dhyr Syncline.

Figure 4.

Photographs of the main allochems of Jebel Dhyr phosphorites illustrating A- Coprolith, B- Pellets, and C- Selachians Teeth.
Photographs of the main allochems of Jebel Dhyr phosphorites illustrating A- Coprolith, B- Pellets, and C- Selachians Teeth.

Figure 5.

Texture of the phosphate samples: A- Bio-pellet phosphorite with a grainstone texture, featuring allochems represented by pellets, intraclasts, and bioclasts (bivalve arc and calcitic bone fragment), [200μm]. B- Bioclasts (vertebra and fish spine) within anisotropic granular phosphorite, [100μm]. C- Phosphatized blunt-edged intraclast (granule) surrounded by pellets and glauconite, [50μm]. D- Cryptocrystalline dolomite rhombohedron with an apatitic rim surrounded by grainstone pellets of various shapes, [50μm]. E- Cylindrical-shaped coprolite and brown-colored intraclast in grainstone textured phosphorite, [100μm]. F- Detrital quartz grains and quartz rim within the calcite-filled crack, [100μm]. G- Dispersed organic matter punctuates within pellets (concentric, non-nucleated, and oval) in a calcitic matrix, [50μm]. H- Globigerina acting as nuclei for a phosphatic ooid, surrounded by non-nucleated, organic-rich oval pellets, [50μm].
Texture of the phosphate samples: A- Bio-pellet phosphorite with a grainstone texture, featuring allochems represented by pellets, intraclasts, and bioclasts (bivalve arc and calcitic bone fragment), [200μm]. B- Bioclasts (vertebra and fish spine) within anisotropic granular phosphorite, [100μm]. C- Phosphatized blunt-edged intraclast (granule) surrounded by pellets and glauconite, [50μm]. D- Cryptocrystalline dolomite rhombohedron with an apatitic rim surrounded by grainstone pellets of various shapes, [50μm]. E- Cylindrical-shaped coprolite and brown-colored intraclast in grainstone textured phosphorite, [100μm]. F- Detrital quartz grains and quartz rim within the calcite-filled crack, [100μm]. G- Dispersed organic matter punctuates within pellets (concentric, non-nucleated, and oval) in a calcitic matrix, [50μm]. H- Globigerina acting as nuclei for a phosphatic ooid, surrounded by non-nucleated, organic-rich oval pellets, [50μm].

Figure 6.

Examples of X-ray diagram for phosphorite sample show the apatitic different component with carbonates and siliceous gangue of Jebel Dhyr syncline. Abbreviations after Warr (2021; IMA–CNMNC).
Examples of X-ray diagram for phosphorite sample show the apatitic different component with carbonates and siliceous gangue of Jebel Dhyr syncline. Abbreviations after Warr (2021; IMA–CNMNC).

Figure 7.

Examples of X-ray patterns showing the presence of sulphides and sulphates in phosphorites samples from Jebel Dhyr syncline.
Examples of X-ray patterns showing the presence of sulphides and sulphates in phosphorites samples from Jebel Dhyr syncline.

Figure 8.

XRD diffractograms of fine fraction phosphorite samples from Jebel Dhyr syncline showing zeolites, feldspars and clays.
XRD diffractograms of fine fraction phosphorite samples from Jebel Dhyr syncline showing zeolites, feldspars and clays.

Figure 9.

Diffractogram of a phosphate granule sample from the Jebel Dhyr syncline.
Diffractogram of a phosphate granule sample from the Jebel Dhyr syncline.

Figure 10.

Left: Diffractogram of isolated pellets, Right: Diffractogram of isolated coprolites from the Jebel Dhyr syncline.
Left: Diffractogram of isolated pellets, Right: Diffractogram of isolated coprolites from the Jebel Dhyr syncline.

The concentration of Geochemical elements (wt%) in phosphorites (bulk rock) samples from the Jebel Dhyr syncline, Eastern Algerian Atlas_

Sample IDP2O5CO2MgONa2OK2OCaOSiO2Fe2O3H2OAl2O3SO3FTot. %
D1-I23.1710.71.840.710.1335.19.70.661.620.7711.852.698.85
D1-II22.8610.751.860.60.1334.89.20.71.540.7812.22.898.22
D1’-I24.610.681.780.790.1635.610.30.921.650.8310.12.399.71
D2-II23.410.651.80.70.15359.50.911.620.8111.13.799.34
D2-I20.612.2130.510.21329.630.851.40.9510.56.298.06
D3-II20.211.82.70.550.2134.29.050.821.50.9310.65.998.46
D4-I22.5310.532.450.580.1434.19.150.651.650.7911.84.999.27
D4-II20.811.62.50.590.1233.99.10.61.70.7411.94.698.15
D4’-I21.911.72.90.60.1134.19.10.551.750.7211.953.298.58
D5-II23.810.92.70.610.133.019.80.51.920.712.43.299.64
D6-I24.612.62.350.520.1232.29.10.851.580.7410.83.298.66
D6-II25.812.62.320.530.1232.19.20.821.560.7410.92.499.09
D8-I21.811.332.690.60.1732.710.611.630.8612.14.499.88
D7-II22.212.12.80.610.132.19.40.851.620.712.154.298.83

Recapitulation of mineral phases identified by light microscopy, X-ray diffraction and macroscopics observations, in phosphorites from the Jebel Dhyr syncline, Eastern Algerian Atlas_

Mineral groups encounteredSampling type
Bulk rockPhosphatic allochems grains
apatite (hydroxylapatite, fluorapatite, francolite, dahllite*)++++
Carbonates (calcite, dolomite, magnesian calcite*, ankerite*, dawsonite*)++--
Sulfates (gypsum)+--
Sulfides (pyrite*-cinnabar*-covellite*)+--
Tectosilicates (quartz)+++
Tectosilicates (feldspar, zeolite*)+--
Clays (palygorskite*)++--
Native element (graphite)+--

Crystallographic parameters of the crystalline unit cell of apatite group in phosphorites from the Jebel Dhyr syncline, Eastern Algerian Atlas_

Minerala or b (Å)C (Å)c/aVol. of unit cellChemical formula
fluorapatite9.3716.8850.734523.12Ca5(PO4)3F
hydroxylapatite9.3526.8820.735521.26Ca5(PO4)3(OH)
francolite9.3406.8800.736519.77(Ca,Mg,Sr,Na)10(PO4,SO4,CO3)6F2-3
dahllite9.4506.8850.725532.09Ca5(PO4,CO3)3(OH,O)

Comparative X-ray diffraction parameters (dhkl) of apatite group from phosphorites deposits in North Africa_

(hkl) (Miller index)dhklof peaks (Å)
J. Jebs, Tunisia (Beji-Sassi 1984)Foum Selja,Tunisia (Chaabani 1978)Morocco (El Haddi 2014)Dhyr, Algeria (this study)
1008.1648.158.0748.099
1015.2815.295.2505.244
2004.0524.044.0414.049
1113.8733.873.8623.867
0023.4563.453.4443.441
1023.1833.173.1703.167
1203.0623.053.0513.061
2112.7922.792.7922.796
112---2.782.7712.771
3002.6952.692.6932.699
2022.6272.622.6222.622
3012.5072.512.5102.513
1222.2842.282.282’2.287
3102.2402.242.2402.240
1312.1302.132.1312.135
1132.0622.072.0612.059
2031.997---1.9961.995
2221.9311.931.9301.933
1321.8791.871.8801.880
1231.8361.841.836---
2311.7881.771.7901.790
4101.7621.761.7651.766
3031.7411.731.743---
0041.7221.711.7231.720
322------1.6321.634

X-ray diffraction parameters of carbonate group in phosphorites from Djebel Dhyr syncline, Eastern Algerian Atlas_

Mineralhkld (Å)2Θ [deg]Geochemical formula
calcite1043.036029.395CaCO3
magnesian calcite1043.025429.500(CaMg)CO3
dolomite1042.889330.815CaMg(CO3)2
ankerite1042.889030.918Ca(Fe,Mg)
(CO3)2
DOI: https://doi.org/10.2478/mipo-2023-0010 | Journal eISSN: 1899-8526 | Journal ISSN: 1899-8291
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Language: English
Page range: 89 - 104
Submitted on: Apr 7, 2023
Accepted on: Nov 26, 2023
Published on: Dec 29, 2023
Published by: Mineralogical Society of Poland
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
phosphorites,
Paleocene-Eocene,
Jebel Dhyr,
XRD,
apatite group
Related subjects:
Geosciences,
Geophysics,
Geosciences, other

© 2023 Salim Boulemia, Riheb Hadji, Salah Bouhlal, Younes Hamed, Houda Besser, Kaouther Ncibi, published by Mineralogical Society of Poland
This work is licensed under the Creative Commons Attribution 4.0 License.

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