Mineralogy, geochemistry and parent rock of Décio bauxite-bearing lateritic profile (Rondon do Pará, Eastern Amazon)

Santos, Pabllo Henrique Costa dos; Costa, Marcondes Lima da

doi:10.1590/2317-4889202120210037

Pabllo Henrique Costa dos Santos ^**Corresponding author.

Universidade Federal do Pará – Belém (PA), Brazil. E-mails: phsantos@ufpa.br, marcondeslc@gmail.com

https://orcid.org/0000-0003-2903-651X

Marcondes Lima da Costa

Universidade Federal do Pará – Belém (PA), Brazil. E-mails: phsantos@ufpa.br, marcondeslc@gmail.com

https://orcid.org/0000-0002-0134-0432

*Corresponding author.

P.S. was responsible for all the mineralogical, micromorphological and chemical analysis, wrote the original draft of the manuscript and prepared the figures. M.C. conceptualized the research, acquired financial resources, was the advisor and improved the manuscript through corrections and suggestions.

Competing interests: the authors declare no competing interests.

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Figure 1.
(A) Geological map of Eastern Amazon (modified from Bizzi et al. 2003Bizzi L.A., Schobbenhaus C., Vidotti R.M., Gonçalves J.H. (eds.). 2003. Geologia, tectônica e recursos minerais do Brasil. Brasília, Companhia de Pesquisa de Recursos Minerais, 692 p.) with the location of the primary bauxite deposits. (B) The geology of Rondon do Pará region (modified from Bizzi et al. 2003Bizzi L.A., Schobbenhaus C., Vidotti R.M., Gonçalves J.H. (eds.). 2003. Geologia, tectônica e recursos minerais do Brasil. Brasília, Companhia de Pesquisa de Recursos Minerais, 692 p.), highlighting the location of the Décio pilot mine.

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Figure 2.
(A) Décio pilot mine, indicating the position of the profiles selected for sampling. (B) The succession of horizons from the Décio lateritic profile.

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Figure 3.
(A) The CBH outcropping in a borehole at the bottom of the Décio pilot mine, from 16.6 to 17.6 m deep. (B) The typical framework of the BXH, showing the domain of reddish cement. (C) Outcrop of the FAD, highlighting the domain of ocher yellow spherulites. (D) A typical sample of the FFAD, which is represented by blocks of FAD embedded in red clay. (E and F) Wavy contact between FFAD, FASH, NBH horizons and the Belterra Clay.

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Figure 4.
Mineralogical composition of the horizons of the Décio lateritic profile.

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Figure 5.
(A) Spherulite from the BXH, with the hematite core and goethite border and (B) crossed nicols. Mass of iron oxi-hydroxide with gibbsite veinlets, cementing the spherulites from the (C) BXH and (D) FAD. (E) The internal constitution of the spherulites from the FASH: gibbsite crystals embedded in a mass of hematite and goethite. (F) Nodules from the NBH showing a gibbsite mass crosscut by veinlets of mesocrystalline gibbsite. Transmitted light with (A, C, D and F) parallel nicols and (B and E) crossed nicols.

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Figure 6.
(A) Zircon, tourmaline, rutile and kyanite grains identified in the Décio lateritic profile. (B) Proportions of heavy minerals, obtained through counting grains under the optical microscope.

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Figure 7.
Vertical distribution of major elements across Décio horizons, based on (A) profile 3 and (B) profile 4.

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Figure 8.
Vertical distribution of minerals across the Décio horizons obtained through stoichiometric calculations.

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Figure 9.
(A) Trace elements in the Décio lateritic bauxite profile normalized to the UCC data (Rudnick and Gao 2003Rudnick R.L., Gao S. 2003. Composition of the continental crust. In: Rudnick R.L. (ed.). The Crust, 3. Amsterdam, Elsevier, p. 1-64.); (B) to the chemical composition of the CBH; (C) to the Itapecuru claystone data after Pantoja (2015)Pantoja H.M. 2015. Mineralogia, geoquímica e minerais pesados do perfil laterito-bauxítico com cobertura e sua relação com o Grupo Itapecuru: lavra piloto Ciríaco (Rondon do Pará). MS Dissertation, Universidade Federal do Pará, Belém, 73 p..

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Figure 10.
Distribution of REE concentrations in the Décio lateritic bauxite profile normalized (A) to the chondrites from Evensen et al. (1978)Evensen N.M., Hamilton P.J., O’Nions R.K. 1978. Rare-earth abundance in chondritic meteorites. Geochimica et Cosmochimica Acta, 42(8):1199-1212. https://doi.org/10.1016/0016-7037(78)90114-X
https://doi.org/https://doi.org/10.1016/... ; (B) to the chemical composition of the Itapecuru claystone according to Pantoja (2015)Pantoja H.M. 2015. Mineralogia, geoquímica e minerais pesados do perfil laterito-bauxítico com cobertura e sua relação com o Grupo Itapecuru: lavra piloto Ciríaco (Rondon do Pará). MS Dissertation, Universidade Federal do Pará, Belém, 73 p.; (C) to the chemical composition of the CBH.

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Figure 11.
Isocon diagrams (Grant 1986Grant J.A. 1986. The Isocon diagram—a simple solution to Gresens’ equation for metasomatic alteration. Economic Geology, 81(8):1976-1982. https://doi.org/10.2113/gsecongeo.81.8.1976
https://doi.org/https://doi.org/10.2113/... ) comparing the main composition of the (A) Décio bauxite (BXH) with the CBH; (B) Itapecuru claystone (Pantoja 2015Pantoja H.M. 2015. Mineralogia, geoquímica e minerais pesados do perfil laterito-bauxítico com cobertura e sua relação com o Grupo Itapecuru: lavra piloto Ciríaco (Rondon do Pará). MS Dissertation, Universidade Federal do Pará, Belém, 73 p.); (C) the UCC (Rudnick and Gao 2003Rudnick R.L., Gao S. 2003. Composition of the continental crust. In: Rudnick R.L. (ed.). The Crust, 3. Amsterdam, Elsevier, p. 1-64.). Al₂O₂, TiO₂, Fe₂O₃, SiO₂, Cr₂O₃ and LOI are presented in Wt. %; trace elements are expressed in ppm.

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Figure 12.
Mass balance of the BXH, considering Al₂O₃ immobile and the CBH as a reference of the parent rock.

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Figure 13.
Mass balance of the BXH, considering Al₂O₃ immobile and the Itapecuru claystone (Pantoja 2015Pantoja H.M. 2015. Mineralogia, geoquímica e minerais pesados do perfil laterito-bauxítico com cobertura e sua relação com o Grupo Itapecuru: lavra piloto Ciríaco (Rondon do Pará). MS Dissertation, Universidade Federal do Pará, Belém, 73 p.) as a reference of the parent rock.

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Figure 14.
Classification of the Décio lateritic horizons based on Fe₂O₃, SiO₂ and Al₂O₃ proportion, according to Bárdossy (1982)Bárdossy G. 1982. Karst bauxites. Amsterdam, Elsevier, 441 p.. The right side of the ternary diagram presents the intensity of lateritization, according to Schellmann (1983)Schellmann W. 1983. A new definition of laterite. Geological Survey of India Memoirs, 120:1-7..

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Figure 15.
(A) Negative linear correlation between Fe₂O₃ x Al₂O₃; (B) non-linear distribution Al₂O₃ x SiO₂; (C) positive linear correlation Al₂O₃ x TiO₂. Trace elements that show positive linear correlation with iron: (D) Fe₂O₃ x Mo; (E) Fe₂O₃ x As; (F) Fe₂O₃ x Pb; (G) Fe₂O₃ x Zn; (I) Fe₂O₃ x V. Zr x ∑REE; (J) Zr x TiO₂.

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Table 1.
Major and trace composition of the Décio bauxite-bearing lateritic profile compared to the average composition of the Upper Continental Crust.

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(1)

Elements	CBH bauxítica		BXH maciça		FAD ferro-luminosa		FFAD desmantelada		FASH ferruginosos		NBH		UCC
	Profile 4		Profile 3	Profile 4	Profile 3	Profile 4	Profile 3	Profile 4	Profile 3	Profile 4	Profile 3	Profile 4	UCC
	17.6 m	16.7 m	16.25 m	16.1 m	15.5 m	15.1 m	14.45 m	13.7 m	13.6 m	12.45 m	13.1 m	12.1 m
Weight %
SiO₂	31.37	29.56	2.27	3.59	3.19	3.42	11.20	7.21	9.76	10.57	6.39	6.58	66.6
Al₂O₃	34.60	35.45	44.38	38.69	24.97	28.23	21.44	20.68	47.84	37.35	57.25	57.44	15.4
Fe₂O₃	14.89	16.12	27.59	34.24	52.15	48.75	50.59	55.58	15.75	29.91	4.85	4.85	5.04
TiO₂	2.37	2.30	1.31	0.83	0.67	0.83	0.74	0.64	1.18	0.96	1.14	1.15	0.64
MnO	0.02	0.03	0.01	nd	nd	nd	0.01	nd	nd	0.02	nd	nd	0.1
MgO	0.01	0.01	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd	2.48
K₂O	0.02	0.02	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd	2.80
P₂O₅	0.05	0.05	0.02	nd	nd	0.02	nd	nd	nd	nd	nd	nd	0.15
LOI	16.4	16.2	24.2	22.4	18.7	18.5	15.6	15.4	25.3	20.9	30.2	29.8	–
Total	99.73	99.74	99.78	99.75	99.69	99.75	99.57	99.51	99.83	99.69	99.83	99.82	–
ppm
Be	nd	1	nd	2	nd	1	nd	1	nd	nd	3	nd	2.1
Sc	16	16	11	9	18	14	32	24	12	26	8	9	14.0
V	261	284	408	418	908	554	1429	1743	314	663	102	103	97
Cr	171	185	164	157	212	212	705	500	240	493	144	144	92
Co	1.7	1.2	2.9	2.0	2.3	1.0	3.0	2.0	2.4	6.2	3.5	8.3	17.3
Ni	1.4	2.4	0.6	0.4	0.9	0.7	1.0	1.3	0.5	1.6	0.3	0.4	47
Cu	3.4	6.1	5.0	5.0	13.6	8.7	25.5	15.0	4.7	38.0	0.8	1.0	28
Zn	3	3	2	2	6	4	8	7	1	9	nd	nd	193
Ga	53.4	54.5	51.4	42.5	43.9	41.7	88.4	68.2	49.7	77.1	39.9	40.3	17.5
As	1.6	1.8	6.2	6.2	11.9	7.3	8.3	8.1	8.4	7.6	1.0	1.1	4.8
Se	nd	nd	nd	0.6	nd	nd	nd	nd	nd	nd	nd	nd	0.09
Rb	0.5	0.5	nd	<0.1	nd	nd	nd	nd	nd	0.2	nd	nd	84
Sr	57.6	74.3	35.8	20.1	15.4	18.5	10.7	7.9	11.0	13.0	11.2	12.6	320
Y	28.5	27.1	16.4	12.7	8.4	10.0	15.4	10.1	15.0	17.5	12.3	13.0	21
Zr	964	904	639	484	340	384	503	402	671	561	545	554	193
Nb	46.4	43.1	25.1	15.5	12.8	15.6	15.3	12.7	24.2	20.3	21.5	23.8	12
Mo	0.7	0.9	1.4	1.3	2.1	1.6	4.1	3.3	1.7	2.7	0.2	0.3	1.1
Ag	nd	nd	nd	0.2	0.4	0.3	0.7	0.5	0.4	0.3	0.1	nd	0.053
Sn	8	7	4	2	2	3	3	2	3	5	4	4	2.1
Sb	0.2	0.3	0.7	0.6	1.0	0.7	1.7	1.7	1.0	1.3	0.1	0.1	0.4
Cs	0.1	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd	4.9
Ba	69	91	43	21	17	21	12	12	13	13	11	12	624
Hf	24.8	24.3	16.7	12.1	9.0	10.1	12.9	10.5	16.3	14.2	13.9	13.4	5.3
Ta	3.1	3.2	1.8	1.2	1.0	1.3	1.3	0.9	1.7	1.4	1.7	1.5	0.9
W	4.2	3.6	5.7	2.6	1.9	2.8	2.0	1.3	3.4	3.2	2.6	2.8	1.9
Au	nd	nd	nd	nd	0.6	nd	1.5	nd	1.1	nd	nd	0.9	0.0015
Hg	0.04	0.05	0.07	0.10	0.45	0.25	0.43	0.58	0.21	0.31	0.09	0.11	0.05
Pb	7.8	10.1	10.3	8.2	11.5	10.0	20.9	17.3	6.6	20.3	1.1	1.2	17
Bi	0.4	0.4	0.4	0.3	0.3	0.3	0.7	0.5	0.6	0.7	0.1	0.2	0.16
Th	45.2	44.2	34.6	30.0	34.0	31.8	50.2	47.7	35.3	46.4	21.7	22.4	10.5
U	3.8	4.0	2.5	1.9	3.2	3.1	7.9	5.6	2.7	6.5	2.3	2.2	2.7
La	71.2	92.4	56.3	30.6	24.1	29.0	20.4	15.3	14.3	21.2	13.9	14.1	31
Ce	102.8	135.5	65.2	35.9	25.6	30.7	30.6	16.3	24.6	47.4	22.3	23.4	63
Pr	9.53	12.01	5.74	3.13	2.63	3.07	3.41	2.00	2.10	3.96	1.91	2.01	7.1
Nd	26.4	33.6	15.8	9.2	7.9	8.3	11.5	6.7	6.6	14.8	5.5	6.4	27
Sm	3.57	5.03	2.16	1.27	1.28	1.26	2.84	1.30	1.36	3.42	1.01	1.17	4.7
Eu	0.81	1.05	0.46	0.29	0.26	0.27	0.61	0.30	0.36	0.77	0.25	0.27	1.0
Gd	3.98	4.78	2.35	1.50	1.22	1.42	2.66	1.43	1.69	3.42	1.39	1.39	4.0
Tb	0.74	0.79	0.43	0.28	0.23	0.26	0.48	0.27	0.34	0.60	0.29	0.30	0.7
Dy	4.96	4.91	3.00	1.84	1.43	1.94	3.14	1.95	2.70	3.62	2.04	2.25	3.9
Ho	1.08	1.08	0.64	0.48	0.33	0.41	0.66	0.39	0.60	0.79	0.45	0.50	0.83
Er	3.68	3.59	2.05	1.54	1.11	1.36	2.29	1.35	2.07	2.78	1.79	1.74	2.3
Tm	0.61	0.60	0.37	0.28	0.19	0.22	0.32	0.24	0.35	0.41	0.30	0.31	0.3
Yb	4.55	4.30	2.68	1.86	1.49	1.73	2.45	1.77	2.70	2.91	2.26	2.18	1.96
Lu	0.74	0.67	0.43	0.30	0.24	0.25	0.37	0.27	0.37	0.44	0.36	0.37	0.31
Ho	1.08	1.08	0.64	0.48	0.33	0.41	0.66	0.39	0.60	0.79	0.45	0.50	0.83
Er	3.68	3.59	2.05	1.54	1.11	1.36	2.29	1.35	2.07	2.78	1.79	1.74	2.3
Tm	0.61	0.60	0.37	0.28	0.19	0.22	0.32	0.24	0.35	0.41	0.30	0.31	0.3
Yb	4.55	4.30	2.68	1.86	1.49	1.73	2.45	1.77	2.70	2.91	2.26	2.18	1.96
Lu	0.74	0.67	0.43	0.30	0.24	0.25	0.37	0.27	0.37	0.44	0.36	0.37	0.31
∑REE	235	300	160	88	68	80	82	50	60	107	54	56	112

[1] *Corresponding author.

Brasil

Brasil

Mineralogy, geochemistry and parent rock of Décio bauxite-bearing lateritic profile (Rondon do Pará, Eastern Amazon)

Abstract