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

Salim Boulemia; Riheb Hadji; Salah Bouhlal; Younes Hamed; Houda Besser; Kaouther Ncibi

doi:10.2478/mipo-2023-0010

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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

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].

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.

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

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].

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

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

Diffractogram of a phosphate granule sample 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 ID	P₂O₅	CO₂	MgO	Na₂O	K₂O	CaO	SiO₂	Fe₂O₃	H₂O	Al₂O₃	SO₃	F	Tot. %
D1-I	23.17	10.7	1.84	0.71	0.13	35.1	9.7	0.66	1.62	0.77	11.85	2.6	98.85
D1-II	22.86	10.75	1.86	0.6	0.13	34.8	9.2	0.7	1.54	0.78	12.2	2.8	98.22
D1’-I	24.6	10.68	1.78	0.79	0.16	35.6	10.3	0.92	1.65	0.83	10.1	2.3	99.71
D2-II	23.4	10.65	1.8	0.7	0.15	35	9.5	0.91	1.62	0.81	11.1	3.7	99.34
D2-I	20.6	12.21	3	0.51	0.21	32	9.63	0.85	1.4	0.95	10.5	6.2	98.06
D3-II	20.2	11.8	2.7	0.55	0.21	34.2	9.05	0.82	1.5	0.93	10.6	5.9	98.46
D4-I	22.53	10.53	2.45	0.58	0.14	34.1	9.15	0.65	1.65	0.79	11.8	4.9	99.27
D4-II	20.8	11.6	2.5	0.59	0.12	33.9	9.1	0.6	1.7	0.74	11.9	4.6	98.15
D4’-I	21.9	11.7	2.9	0.6	0.11	34.1	9.1	0.55	1.75	0.72	11.95	3.2	98.58
D5-II	23.8	10.9	2.7	0.61	0.1	33.01	9.8	0.5	1.92	0.7	12.4	3.2	99.64
D6-I	24.6	12.6	2.35	0.52	0.12	32.2	9.1	0.85	1.58	0.74	10.8	3.2	98.66
D6-II	25.8	12.6	2.32	0.53	0.12	32.1	9.2	0.82	1.56	0.74	10.9	2.4	99.09
D8-I	21.8	11.33	2.69	0.6	0.17	32.7	10.6	1	1.63	0.86	12.1	4.4	99.88
D7-II	22.2	12.1	2.8	0.61	0.1	32.1	9.4	0.85	1.62	0.7	12.15	4.2	98.83

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 encountered	Sampling type
Mineral groups encountered	Bulk rock	Phosphatic 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_

Mineral	a or b (Å)	C (Å)	c/a	Vol. of unit cell	Chemical formula
fluorapatite	9.371	6.885	0.734	523.12	Ca₅(PO₄)₃F
hydroxylapatite	9.352	6.882	0.735	521.26	Ca₅(PO₄)₃(OH)
francolite	9.340	6.880	0.736	519.77	(Ca,Mg,Sr,Na)₁₀(PO₄,SO₄,CO₃)₆F_2-3
dahllite	9.450	6.885	0.725	532.09	Ca₅(PO₄,CO₃)₃(OH,O)

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

(hkl) (Miller index)	d_hklof peaks (Å)
(hkl) (Miller index)	J. Jebs, Tunisia (Beji-Sassi 1984)	Foum Selja,Tunisia (Chaabani 1978)	Morocco (El Haddi 2014)	Dhyr, Algeria (this study)
100	8.164	8.15	8.074	8.099
101	5.281	5.29	5.250	5.244
200	4.052	4.04	4.041	4.049
111	3.873	3.87	3.862	3.867
002	3.456	3.45	3.444	3.441
102	3.183	3.17	3.170	3.167
120	3.062	3.05	3.051	3.061
211	2.792	2.79	2.792	2.796
112	---	2.78	2.771	2.771
300	2.695	2.69	2.693	2.699
202	2.627	2.62	2.622	2.622
301	2.507	2.51	2.510	2.513
122	2.284	2.28	2.282’	2.287
310	2.240	2.24	2.240	2.240
131	2.130	2.13	2.131	2.135
113	2.062	2.07	2.061	2.059
203	1.997	---	1.996	1.995
222	1.931	1.93	1.930	1.933
132	1.879	1.87	1.880	1.880
123	1.836	1.84	1.836	---
231	1.788	1.77	1.790	1.790
410	1.762	1.76	1.765	1.766
303	1.741	1.73	1.743	---
004	1.722	1.71	1.723	1.720
322	---	---	1.632	1.634

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

Mineral	hkl	d (Å)	2Θ [deg]	Geochemical formula
calcite	104	3.0360	29.395	CaCO₃
magnesian calcite	104	3.0254	29.500	(CaMg)CO₃
dolomite	104	2.8893	30.815	CaMg(CO₃)₂
ankerite	104	2.8890	30.918	Ca(Fe,Mg)
				(CO₃)₂

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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:

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© 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.

Volume 54 (2023): Issue 1 (January 2023)

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

Figures & Tables

Figure 1.

Figure 2.

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Figure 10.

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

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

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

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

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

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