Reappraisal of the Sumé Complex: geochemistry and geochronology of metaigneous rocks and implications for Paleoproteorozoic subduction-accretion events in the Borborema Province, NE Brazil

Santos, Edilton José dos; Santos, Lauro Cézar Montefalco de Lira

doi:10.1590/2317-4889201920180083

Edilton José dos Santos

Serviço Geológico do Brasil - Recife (PE), Brazil.

† In memoriam.

https://orcid.org/0000-0001-7683-3533

Lauro Cézar Montefalco de Lira Santos ^**Corresponding author.

Department of Geology, Universidade Federal de Pernambuco - Recife (PE), Brazil. E-mail: lauromontefalco@gmail.com

https://orcid.org/0000-0001-6098-1873

*Corresponding author.

^†
In memoriam.

Competing interests: The authors declare no competing interests.

Figures (9)
Tables (3)

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Figure 1.
(A) Geodynamic context of the Borborema Province in pre-drift reconstruction for West Africa and northeastern South America; (B) tectonic framework of the Borborema Province; (B) simplified geological map of the Transversal sub-province and its domains with the study area highlighted.

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Figure 2.
Simplified geological map of the study area showing the location of the selected sample for U-Pb zircon dating.

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Figure 3.
(A) Modal composition of the studied metagranitoids obtained by point counting; (B) rounded contact of alkali feldspar granite and pyroxenites, suggestive of preserved magma mingling; (C) foliated syenogranite of the outcrop selected for U-Pb dating; (D) metric layers of fine-grained massive metagabros; (E) deformed and elongated hornblende crystals following the regional foliation imposed on an amphibolite sample.

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Figure 4.
U-Pb concordia diagram and back scattered electrons (BSE) images of selected zircon crystals with spot positioning of sample SC-05 (biotite metasyenogranite).

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Figure 5.
Nd evolution diagram for the studied rocks in the Sumé region.

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Figure 6.
Major element plots for the studied samples (data from ). (A) TAS diagram (Na₂O + K₂O vs. SiO₂), from Le Bas et al. (1986Le Bas M.J., Le Maitre R.W., Streckeisen A., Zanettin B. 1986. A chemical classification of volcanic rocks based on the total alcali-silica diagram. Journal of Petrology, 27(3):745-750. https://doi.org/10.1093/petrology/27.3.745
https://doi.org/10.1093/petrology/27.3.7... ); (B) AFM diagram from Irvine and Baragar (1971Irvine T.N., Baragar W.R.A. 1971. A guide to chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 8(5):523-548. https://doi.org/10.1139/e71-055
https://doi.org/10.1139/e71-055... ); (C) A/NK vs. ASI diagram, from Maniar and Picolli (1989Maniar P.D., Piccoli P.M. 1989. Tectonic discrimination of granitoids. Geological Society of America Bulletin, 101(5):635-643. https://doi.org/10.1130/0016-7606(1989)101%3C0635:TDOG%3E2.3.CO;2
https://doi.org/10.1130/0016-7606(1989)1... ), using Shand’s index. Blue circles are metagranitic rock samples, and green circles represent metamafic rock samples.

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Figure 7.
Chondrite-normalized spider diagrams (A) and (C) and rare earth elements (REE) patterns for the studied rocks (B) and (D). Standardization followed Nakamura (1974Nakamura N. 1974. Determination of REE, Ba, Fe, Mg, Na and K in carbonaceous and ordinary chondrites. Geochemhimica et Cosmochimica Acta, 38(5):757-775. https://doi.org/10.1016/0016-7037(74)90149-5
https://doi.org/10.1016/0016-7037(74)901... ) normalizing values. Symbols are as in .

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Figure 8.
Discriminant diagrams of the studied rocks. (A) Hf-Rb/30-3Ta plot after Harris et al. (1986Harris N.B.W., Pearce J.A., Tindle A.G. 1986. Geochemical characteristics of collision zone magmatism. In: Coward M.P., Reis A.C. (Eds.). Collision Tectonics. Geological Society Special Publication, v. 19, p. 67-81.); (B) Y vs. Nb after Pearce et al. (1984Pearce J.A., Harris N.B.W., Tindle A.G. 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25(Part 4):956-983.). Fields indicate syn-collisional granites (syn-COLG), within-plate granites (WPG), volcanic arc-related granites (VAG) and ocean-ridge granites (ORG).

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Figure 9.
Discriminant diagrams of the studied rocks of the Sumé Complex. (A) Hf/3-Th-Ta plot after Wood (1980Wood D.A. 1980. The application of a Th-Hf-Ta diagram to problems of tectonomagmatic classification and to establishing the nature of crustal contamination of basaltic lavas of the British Tertiary volcanic province. Earth and Planetary Science Letters, 50(1):11-30. http://dx.doi.org/10.1016/0012-821X(80)90116-8
http://dx.doi.org/10.1016/0012-821X(80)9... ), Nb/Th vs. Y plot after Jenner et al. (1991Jenner G.A., Dunning G.R., Malpas J., Brown M., Brace T. 1991. Bay of Islands and Little Port Complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction zone origin. Canadian Journal of Earth Science, 28(10):1635-1652. https://doi.org/10.1139/e91-146
https://doi.org/10.1139/e91-146... ); (B) and (C) discriminant functions DF1 vs. DF2 plot from Agrawal et al. (2008Agrawal S., Guevara M., Verma S.P. 2008. Tectonic discrimination of basic and ultrabasic volcanic rocks through log-transformed ratios of immobile trace elements. International Geology Review, 50(12):1057-1079. http://doi.org/10.2747/0020-6814.50.12.1057
http://doi.org/10.2747/0020-6814.50.12.1... ). Fields indicate mid-ocean ridge basalts (MORB and N-MORB), enriched mid ocean ridge basalts (E-MORB), ocean island basalts (OIB), island arc basalts (IAB) and continental rift basalts (CRB). Symbols are as in .

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Table 1.
Summary of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) data of zircon grains from sample SC-05.

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Table 2.
Summary of Nd isotope data for the metaplutonic rocks of the Sumé region. Samples SC-51, 14, and 05 stand for metagranitic members, whereas SC-78 corresponds to an amphibolite.

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Table 3.
Major (wt. %) and trace element (ppm) concentrations of studied metaigneous rocks, Alto Moxotó Terrane, NE Brazil.

Grain spot	²⁰⁷ Pb/ ²⁰⁶ Pb ratios	± (1σ)	²⁰⁷ Pb/ ²³⁵ U ratios	± (1σ)	²⁰⁶ Pb/ ²³⁸ U ratios	± (1σ)	²⁰⁷ Pb/ ²⁰⁶ Pb ages	± (1σ)	²⁰⁷ Pb/ ²³⁵ U ages	± (1σ)	²⁰⁶ Pb/ ²³⁸ U ages	± (1σ)	Rho	Th/U ratio	Conc. (%)
Z07	0.12	1.96	5.57	3.08	0.34	2.37	1919.71	34.78	1910.91	26.51	1901.76	39.08	0.77	0.23	99.05
Z01	0.13	0.90	6.44	2.41	0.35	2.23	1957.53	16.00	2038.01	21.14	1928.00	37.17	0.93	0.29	96.31
Z30	0.12	1.10	5.65	2.21	0.34	1.92	1962.20	19.50	1924.35	19.07	1885.72	31.34	0.86	0.13	96.06
Z14	0.12	2.30	5.89	3.77	0.35	2.99	1925.52	40.59	1959.29	32.71	1939.67	50.05	0.79	0.13	100.13
Z05	0.13	0.85	5.92	1.39	0.34	1.10	1999.76	15.01	1963.52	12.09	1900.72	18.15	0.78	0.10	94.72
Z02	0.12	1.43	5.82	2.50	0.35	2.05	1971.14	25.30	1950.08	21.64	1924.87	34.05	0.82	0.59	97.59
Z06	0.13	1.37	5.99	2.19	0.35	1.70	1985.71	24.24	1973.78	19.04	1920.78	28.30	0.77	0.61	96.25
Z12	0.12	1.81	5.85	2.73	0.35	2.05	1953.32	32.02	1954.17	23.71	1951.20	34.45	0.76	0.12	99.85
Z04	0.12	2.64	5.86	4.08	0.36	3.11	1937.17	46.51	1955.61	35.37	1969.65	52.74	0.76	0.16	101.49
Z26	0.12	1.07	6.03	1.56	0.36	1.14	1964.25	19.01	1980.03	13.62	1994.45	19.52	0.71	0.10	101.50
Z11	0.12	1.94	6.06	3.22	0.36	2.57	1984.21	34.06	1984.47	28.05	1979.73	43.81	0.80	0.63	99.72
Z09	0.13	2.71	6.31	4.59	0.37	3.70	1974.23	47.59	2019.38	40.20	2010.02	63.85	0.81	17.98	101.22
Z25	0.12	0.80	6.10	1.53	0.36	1.31	1984.43	14.14	1989.95	13.35	1993.79	22.38	0.85	0.08	100.39
Z08	0.12	2.64	6.20	4.02	0.38	3.03	1952.29	46.48	2004.08	35.13	2053.59	53.22	0.76	0.11	105.13
Z27	0.12	1.80	6.20	2.50	0.36	1.75	1998.15	31.57	2004.93	21.90	2005.12	30.07	0.76	1.48	100.02
Z20	0.12	0.60	6.31	2.09	0.37	2.01	2005.95	10.57	2019.15	18.35	2030.50	34.96	0.96	0.24	101.14
Z15	0.12	1.92	6.54	3.10	0.39	2.44	1993.83	33.66	2050.78	27.30	2106.31	43.79	0.78	0.31	105.56
Z18	0.12	1.06	6.61	1.77	0.40	1.42	1958.01	18.79	2060.96	15.64	2164.66	26.16	0.80	0.30	110.51

Sample	Sm (ppm)	Nd (ppm)	¹⁴³ Nd/ ¹⁴⁴ Nd	εNd (0)	εNd (t)	U-Pb age (Ga)	T_DM (Ga)
SC-51	20.05	1,333.5	0.511437	-23.43	-0.08	1.997	2.97
SC-14	1.02	5.17	0.511099	-30.02	-10.44	1.997	2.97
SC-05	7.67	48.01	0.510916	-30.17	-4.89	1.997	2.97
SC-78	5.58	32.21	0.511120	-29.61	-6.40	1.997	2.97

Sample	SC05*	SC14*	SC27*	SC51*	SC71*	SC135A*	SC05B**	SC14**	SC34**	SC37**	SC71A**	SC78**	LSM75**
Major elements (wt.%)
SiO₂	72.11	69.51	61.31	75.49	72.37	68.54	50	46.83	48.07	47.43	51.03	47.63	49.9
Al₂O₃	15.29	14.17	15.9	13.03	12.91	14.84	6.76	10.26	5.64	7.08	8.87	6.12	3.18
CaO	1.22	1.51	3.3	1.34	4.9	2.95	22.11	18.53	22.7	22.08	19.78	22.82	20.7
Fe₂O₃	0.051	0.82	2.06	1.19	1.09	2.18	5.9	11.13	6.78	7.91	6.53	8.54	9.43
FeO	0.045	0.74	1.85	1.07	0.98	1.96	5.31	10.02	6.1	7.12	5.88	7.69	8.48
K₂O	6.73	10.46	10.87	4.76	4.86	5.62	0.19	1	0.13	0.14	0.99	0.17	0.19
MgO	0.08	0.22	1.47	0.06	0.59	0.95	11.82	8.23	12.71	9.97	7.44	11.63	13.4
MnO	0.01	0.01	0.05	0.02	0.03	0.04	0.29	0.33	0.35	0.44	0.21	0.3	0.62
Na₂O	2.84	1.01	1.85	3.05	1.42	2.81	0.67	1.14	0.38	0.87	1.25	0.35	0.58
P₂O₅	0.05	0.06	0.3	0.03	0.22	0.18	n.d.	0.13	0.02	0.02	1.77	n.d.	0.01
TiO₂	0.04	0.65	0.07	0.06	0.06	0.14	0.25	0.53	0.38	0.24	0.3	0.54	0.26
Total	98	99	99	100	99	100	103	108	103	103	104	105	106
Trace elements (ppm)
Ba	835	1917	2534	91	2317	1749	33	267	343	120	458	270	121
Ce	75	50.8	130.8	17.1	44.2	145.5	34.5	74	57.1	34	166.1	24.5	202.4
Dy	0.9	1.7	1.7	0.7	1	2.3	2.2	4	2.8	1.1	3.2	2.7	4.8
Er	0.3	0.9	0.6	0.4	0.5	1.1	1.1	1.9	1.2	0.5	1.7	1.4	2.3
Eu	1	0.7	0.5	0.4	0.4	1.2	0.6	0.9	1.2	1.4	1.1	0.5	1.7
Ga	16.5	11.7	14.2	15.3	13	17.3	12.5	16.1	11.3	13.6	18.1	8.9	9.1
Gd	1.5	2.1	2.9	0.7	1.7	3.4	2.7	4.9	4.3	1.1	4.6	2.3	6.4
Hf	0.3	8.2	1	1.5	1.1	2.3	4.2	1.8	2.3	3.5	2.1	1.7	1.8
Ho	0.1	0.3	0.3	0.1	0.2	0.4	0.4	0.8	0.5	0.2	0.6	0.5	0.9
La	74.3	21.6	44.2	9.2	25.7	88	12.9	32.4	50.2	17	81.1	10.7	94.4
Lu	0.1	0.1	0.1	0.1	0.1	0.1	0.2	0.3	0.2	0.1	0.3	0.2	0.3
Nb	1.2	3.2	2.8	4.4	1.9	2.9	2.2	6.8	1.6	0.7	5	0.7	0.4
Nd	29.5	20.7	36.3	6.5	17	48.1	20.2	32.1	46.5	12.6	58.5	14.4	68.3
Pr	9.9	5.6	10.3	1.8	4.9	15.2	4.9	8.7	12.5	13.7	16.6	3.4	20.2
Rb	200.4	285.5	354	82.8	106.3	98.6	4.5	30.8	4	3.5	21.1	6.7	3.7
Sm	3.1	3.4	5.4	1.1	2.4	5.8	3.7	6.1	6.9	2.1	7.5	2.7	9.7
Sn	n.d.	6	1	n.d.	n.d.	1	5	3	3	3	3	7	4
Sr	182.4	267.8	322.8	112.9	734.6	400.3	94.2	233.9	122.2	222	866.3	173.5	71.6
Ta	0.1	0.8	0.3	0.3	0.1	0.1	0.6	0.8	0.3	0.1	0.5	0.2	0.1
Tb	0.2	0.3	0.4	0.1	0.2	0.5	0.4	0.7	0.6	0.2	0.6	0.4	0.9
Th	4	16.3	13	4	8.3	28.7	2.3	3	1.7	1.2	4.44	0.9	1.8
Tm	0.1	0.2	0.1	0.1	0.1	0.1	0.2	0.3	0.2	0.1	0.3	0.2	0.3
U	0.4	1.7	1	1.3	0.8	0.8	0.7	0.8	0.3	0.1	3.7	0.6	0.8
V	n.d.	17	9	n.d.	35	40	45	91	50	65	61	150	88
Y	3.9	9.4	7.1	3.4	5.4	10.5	11.2	22.1	12.8	5.4	16.5	12.6	24.8
Yb	0.2	1	0.4	0.5	0.5	0.1	1.1	1.9	1.1	0.6	1.7	1.4	2.1

[1] *Corresponding author.

Brasil

Brasil

Reappraisal of the Sumé Complex: geochemistry and geochronology of metaigneous rocks and implications for Paleoproteorozoic subduction-accretion events in the Borborema Province, NE Brazil

Abstract