The 9 Mile Deposit of the Barama-Mazaruni Greenstone Belt of the Guiana Shield: geochemistry, geochronology and regional significance

Bassoo, Roy; Murphy, James Brendan

doi:10.1590/2317-4889201820180072

Roy Bassoo ^**Corresponding author.

Department of Geosciences, Baylor University - Waco (TX), United States. E-mail: roy_bassoo1@baylor.edu

Department of Earth Sciences, Saint Francis Xavier University - Antigonish, Nova Scotia, Canada. E-mail: bmurphy@stfx.ca

https://orcid.org/0000-0003-0324-9541

James Brendan Murphy

Department of Earth Sciences, Saint Francis Xavier University - Antigonish, Nova Scotia, Canada. E-mail: bmurphy@stfx.ca

https://orcid.org/0000-0003-2269-1976

*Corresponding author.

Figures (15)
Tables (4)

Thumbnail

Figure 1.
Simplified geologic map of the Guiana Shield (modified from Voicu 2001Voicu G., Bardoux M., Stevenson R. 2001. Lithostratigraphy, geochronology and gold metallogeny in the Northern Guiana Shield, South America: A review. Ore Geology Reviews, 18(3-4):211-236. http://dx.doi.org/10.1016/S0169-1368(01)00030-0
http://dx.doi.org/10.1016/S0169-1368(01)... , Daoust et al. 2011Daoust C., Voicu G., Brisson H., Gauthier M. 2011. Geological Setting of the Paleoproterozoic Rosebel gold district, Guiana Shield, Suriname. Journal of South American Earth Sciences, 32(3):222-245. http://dx.doi.org/10.1016/j.jsames.2011.07.001
http://dx.doi.org/10.1016/j.jsames.2011.... , Delor et al. 2003Delor C., Lahondère D., Egal E., Lafon J.M., Cocherie A., Guerrot C., Rossi P., Truffert C., Théveniaut H., Phillips D., de Avelar V.G. 2003. Trans-Amazonian crustal growth and reworking as revealed by the 1:500,000 scale geological map of French Guyana (2nd edition). Geology of France and surrounding areas. Special Guyana Shield. BRGM - SGF, 2-4:5-57., Guiraud et al. 2017Guiraud G., Tremblay A., Jebrak M. 2017. The Rhyacian “Montagne d’Or” auriferous volcanogenic massive sulphide deposit, French Guiana, South America: stratigraphy and geochronology. In: SGA Biennial Meeting, 14., Québec, Canada. Proceedings… v. 1.).

Thumbnail

Figure 2.
Regional geologic map (modified from Voicu et al. 1999Voicu G., Bardoux M., Jebrak M., Crepeau R. 1999. Structural, Mineralogical and Geochemical Studies of the Paleoproterozoic Omai Gold Deposit, Guyana. Economic Geology, 94(8):1277-1303. https://doi.org/10.2113/gsecongeo.94.8.1277
https://doi.org/10.2113/gsecongeo.94.8.1... ) showing the spatial relationship between gold deposits, the Makapa-Kuribrong Shear Zone (MKSZ) and the Issano Appaparu Shear Zone (IASZ).

Thumbnail

Figure 3.
Geological sketch map of the 9 Mile Deposit.

Thumbnail

Figure 4.
SiO2 vs. FeO/(FeO + MgO) plot. Dividing line between Ferroan and Magnesian after Frost et al. (2001Frost B.R., Barnes C.G., Collins W.J., Arculus R.J., Ellis D.J, Frost C.D. 2001. A Geochemical Classification for Granitic Rocks. Journal of Petrology, 42(11):2033-2048. https://doi.org/10.1093/petrology/42.11.2033
https://doi.org/10.1093/petrology/42.11.... ).

Thumbnail

Figure 5.
FeO^t/MgO vs. SiO2 plots for subalkalic rocks (after Miyashiro 1974Miyashiro A. 1974. Volcanic rock series in island arcs and active continental margin. American Journal of Science, 274(4):321-355. https://doi.org/10.2475/ajs.274.4.321
https://doi.org/10.2475/ajs.274.4.321... ), showing the slope of mafic dykes of the 9 Mile Deposit. Note that the dashed line is a reference slope. Rocks that have steeper trends than the reference slope are classified as tholeiitic, whereas rocks that have shallower trends than the reference slope are classified as calc-alkalic. Numbers correspond to samples listed in ^{Supplementary Table A1} Supplementary data associated with this article can be found in the online version: Suplementary Figures A1 to A10 and Suplementary Table A1 and A2. .

Thumbnail

Figure 6.
Zr/TiO2 vs. Nb/Y discrimination diagram (after Winchester & Floyd 1977Winchester J.A., Floyd P.A. 1977. Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chemical Geology, 20:325-343. https://doi.org/10.1016/0009-2541(77)90057-2
https://doi.org/10.1016/0009-2541(77)900... ). Numbers correspond to samples listed in ^{Supplementary Table A1} Supplementary data associated with this article can be found in the online version: Suplementary Figures A1 to A10 and Suplementary Table A1 and A2. .

Thumbnail

Figure 7.
Nb vs. Y discrimination diagram (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, 25:956-983. http://dx.doi.org/10.1093/petrology/25.4.956
http://dx.doi.org/10.1093/petrology/25.4... ). Numbers correspond to samples listed in ^{Supplementary Table A1} Supplementary data associated with this article can be found in the online version: Suplementary Figures A1 to A10 and Suplementary Table A1 and A2. .

Thumbnail

Figure 8.
Ta vs. Yb discrimination diagram (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, 25:956-983. http://dx.doi.org/10.1093/petrology/25.4.956
http://dx.doi.org/10.1093/petrology/25.4... ). Numbers correspond to samples listed in ^{Supplementary Table A1} Supplementary data associated with this article can be found in the online version: Suplementary Figures A1 to A10 and Suplementary Table A1 and A2. .

Thumbnail

Figure 9.
Plot of chondrite-normalized (after McDonough & Sun 1995McDonough W.F., Sun S.S. 1995. The Composition of the Earth. Chemical Geology, 120(3-4):223-253. https://doi.org/10.1016/0009-2541(94)00140-4
https://doi.org/10.1016/0009-2541(94)001... ) rare earth elements (REE) values and mid ocean ridge basalt (MORB)-normalized (after Pearce & Parkinson 1993Pearce J.A., Parkinson I.J. 1993. Trace element models for mantle melting: application to volcanic arc petrogenesis. In: Prichard H.M., Alabaster T., Harris N.B.W., Neary C.R. (Eds), Magmatic Processes and Plate Tectonics. Geological Society Special Publications, 76:373-403.) multi-element values of samples of granodiorite, mafic dyke and meta rhyolite. Numbers correspond to samples listed in ^{Supplementary Table A1} Supplementary data associated with this article can be found in the online version: Suplementary Figures A1 to A10 and Suplementary Table A1 and A2. .

Thumbnail

Figure 10.
Zr-Y plot classifying samples according to their magma source (after Winchester & Floyd 1977Winchester J.A., Floyd P.A. 1977. Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chemical Geology, 20:325-343. https://doi.org/10.1016/0009-2541(77)90057-2
https://doi.org/10.1016/0009-2541(77)900... ). Numbers correspond to samples listed in ^{Supplementary Table A1} Supplementary data associated with this article can be found in the online version: Suplementary Figures A1 to A10 and Suplementary Table A1 and A2. .

Thumbnail

Figure 11.
Ti vs. Zr discrimination diagram (after Pearce 1982Pearce J.A. 1982. Trace element characteristics of lavas from destructive plate boundaries. In: Thorpe R.S. (Ed.), Andesites. New York: Wylie and Sons, p. 525-548.). Numbers correspond to samples listed in ^{Supplementary Table A1} Supplementary data associated with this article can be found in the online version: Suplementary Figures A1 to A10 and Suplementary Table A1 and A2. .

Thumbnail

Figure 12.
Cathode luminescence zircon images, showing locations of U-Pb isotope analyses. The aperture width of the laser is 30 microns.

Thumbnail

Figure 13.
Concordia plot of ²⁰⁶Pb/²³⁸U vs. ²⁰⁷Pb/²³⁵U for sample 13.

Thumbnail

Figure 14.
Concordia plot of ²⁰⁷Pb/²⁰⁶Pb vs. ²³⁸U/²⁰⁶Pb for sample 13.

Thumbnail

Figure 15.
Plot showing weighted mean derived age and error limits of each ²⁰⁷Pb/²⁰⁶Pb ratio for sample 13.

Thumbnail

Table 1.
Tectonic sequence of events of the Barama-Mazaruni formation of the Guiana Shield*.

Thumbnail

Table 2.
Tectonic sequence of events of the 9 Mile Deposit*.

Thumbnail

Table 3.
U and Pb isotopic compositions and ages of zircons from the 9 Mile Deposit granodiorite.

Thumbnail

Table 4.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) trace element analysis data.

Tectonic Episode	Event	U-Pb Age Constraints (Ga)
Post Trans-Amazonian Orogeny	Deposition of the Roraima Formation	1.68 - 1.57
	Intrusion of Avanavero mafic dykes and sills	1.59 - 1.97
	Deposition of Central Iwokrama Formation felsic volcanogenic sedimentary rocks and intrusion of post-tectonic granitoids	1.875 - 1.75
Late Trans-Amazonian Orogeny	Deposition of Muruwa sandstones, siltstones and conglomerates. Intrusion of Uatumã granites	2.08 - 1.93
Early Trans-Amazonian Orogeny	Formation of greenstone belt stratigraphy in the Guiana Shield, including protoliths of gneisses and amphibolites of the Maroni-Itacaiunas belt	2.26 - 2.13

Tectonic setting	Event	Comments	U-Pb age range (Ga) From the literature	U-Pb measured Age (Ga) This study
Late Trans-Amazonian Orogeny	Intrusion of mafic dykes	Parallel to E-W and NE-SW shear foliations	2.07 - 1.93
	E-W shearing	Auriferous quartz veins parallel to E-W shear zone and NW-SE enechelon shear fractures	2.07 - 1.93
	Quartz veining parallel to NE-SW thrust	Auriferous quartz veins. Euhedral pyrite and xenoliths of granodiorite are found within quartz veins	2.07 - 1.93
Main Trans-Amazonian Orogeny	NE-SW thrust faulting	Thrust faulted contact of meta-rhyolite and granodiorite	2.11 - 2.08
	Intrusion of granodiorite		2.26 - 2.13	2.142 ± 0.17 - 2.147 ± 0.12
	NW-SE shearing of rhyolite	Marked by stretched and deformed ankerite and dolomite	2.26 - 2.13
	Deposition of rhyolite		2.26 - 2.13

Zircon Spot Sample	²⁰⁶ Pb (%)	U (ppm)	Th (ppm)	²³² Th/ ²³⁸ U	Pb (ppm)	²⁰⁶ Pb/ ²³⁸ U Age (Ma) ± 2σ	²⁰⁷ Pb/ ²⁰⁶ Pb Age (Ma) ± 2σ	Discordant %	²³⁸ U/ ²⁰⁶ Pb ± 1σ	²⁰⁷ Pb/ ²⁰⁶ Pb ± 1σ	²⁰⁷ Pb/ ²³⁵ U ± 1σ	²⁰⁶ Pb/ ²³⁸ U ± 1σ	Error Correction
YK 109 1.1	0.19	90.00	39.40	0.45	30.60	2141 ± 25	2147 ± 27	0.32	2.54 ± 1.40	0.13 ± 1.50	7.26 ± 2.10	0.39 ± 1.40	0.67
YK 109 2.1	0.12	126.00	75.20	0.62	39.20	1988 ± 22	2144 ± 22	7.83	2.77 ± 1.30	1.33 ± 1.30	6.65 ± 1.80	0.36 ± 1.30	0.71
YK 109 3.1	0.21	115.00	52.00	0.47	39.00	2136 ± 26	2151 ± 24	0.71	2.55 ± 1.40	1.34 ± 1.40	7.26 ± 2.00	0.39 ± 1.40	0.72
YK 109 4.1	0.12	174.00	134.00	0.79	59.10	2140 ± 23	2151 ± 18	0.52	2.54 ± 1.30	0.13 ± 1.10	7.27 ± 1.60	0.39 ± 1.30	0.77
YK 109 5.1	0.28	179.00	116.00	0.67	60.90	2147 ± 23	2158 ± 19	0.50	2.53 ± 1.30	0.13 ± 1.10	7.33 ± 1.70	0.40 ± 1.30	0.76
YK 109 6.1	0.25	82.00	36.90	0.47	27.90	2147 ± 28	2121 ± 28	-1.21	2.53 ± 1.50	0.13 ± 1.60	7.18 ± 2.20	0.40 ± 1.50	0.68
YK 109 7.1	0.10	76.00	52.00	0.71	25.40	2112 ± 26	2099 ± 28	-0.61	2.58 ± 1.40	0.13 ± 1.60	6.95 ± 2.10	0.39 ± 1.40	0.67
YK 109 8.1	0.20	95.00	40.90	0.44	32.40	2143 ± 25	2134 ± 26	-0.39	2.54 ± 1.40	0.13 ± 1.50	7.21 ± 2.00	0.39 ± 1.40	0.68
YK 109 9.1	0.10	179.00	96.70	0.56	60.60	2140 ± 23	2158 ± 19	0.86	2.54 ± 1.30	0.13 ± 1.10	7.30 ± 1.70	0.39 ± 1.30	0.76
YK 109 10.1	0.54	71.00	49.60	0.73	24.00	2134 ± 26	2156 ± 31	1.02	2.54 ± 1.50	0.13 ± 1.80	7.27 ± 2.3	0.39 ± 1.50	0.64

Sample	Rock Type	SiO₂ (%)	Al₂O₃ (%)	Fe₂O₃ (%)	MnO (%)	MgO (%)	CaO (%)	Na₂O (%)	K₂O (%)	TiO₂ (%)	P₂0₅ (%)	LOI (%)	Total (%)
Sample 1	Granodiorite	72.36	13.12	3.29	0.05	0.87	2.20	3.91	2.17	0.42	0.07	1.27	99.72
Sample 2	Granodiorite	73.00	12.48	4.08	0.05	0.88	1.91	3.63	1.49	0.49	0.05	1.75	99.81
Sample 6	Mafic Dyke	52.56	15.07	10.62	0.14	6.56	6.49	2.78	1.70	0.77	0.25	3.31	100.20
Sample 7	Mafic Dyke	52.83	15.85	9.66	0.14	4.61	6.74	2.39	3.05	0.83	0.24	2.84	99.18
Sample 8	Mafic Dyke	52.15	14.27	10.76	0.15	7.08	7.20	1.75	2.17	0.80	0.16	3.83	100.30
Sample 9	Granodiorite	78.10	12.29	1.30	0.02	0.13	0.62	3.55	4.00	0.13	0.01	0.80	101.00
Sample 10	Meta Rhyolite	72.52	13.88	2.43	0.05	0.37	1.81	3.96	2.17	0.22	0.06	2.32	99.78
Sample 11	Granodiorite	71.11	13.64	3.26	0.05	1.10	2.25	2.16	2.95	0.42	0.10	3.75	100.80
Sample 12	Granodiorite	69.95	14.24	3.26	0.05	0.95	2.29	2.61	2.85	0.43	0.09	3.58	100.30
Sample 13	Granodiorite	70.92	13.95	3.36	0.05	0.98	2.76	4.14	2.25	0.44	0.09	1.19	100.10
Sample 14	Granodiorite	69.31	13.73	3.43	0.06	1.05	3.20	1.12	3.62	0.41	0.09	4.59	100.60
Sample 15	Mafic Dyke	54.13	14.90	8.57	0.13	4.18	7.14	3.50	2.58	0.91	0.47	2.93	99.45
		Sc (ppm)	Be (ppm)	V (ppm)	Cr (ppm)	Co (ppm)	Ni (ppm)	Cu (ppm)	Zn (ppm)	Ga (ppm)	Ge (ppm)	As (ppm)	Rb (ppm)
Sample 1	Granodiorite	6	1	37	< 20	6	< 20	< 10	40	17	1.3	< 5	50
Sample 2	Granodiorite	6	1	42	< 20	7	< 20	< 10	40	17	1.4	< 5	36
Sample 6	Mafic Dyke	28	2	196	170	35	60	60	80	16	1.8	< 5	52
Sample 7	Mafic Dyke	23	2	195	< 20	29	30	40	90	18	1.7	< 5	93
Sample 8	Mafic Dyke	29	1	207	190	38	70	60	80	17	1.8	< 5	74
Sample 9	Granodiorite	1	1	10	< 20	1	< 20	< 10	< 30	13	1.5	< 5	69
Sample 10	Meta Rhyolite	3	2	7	< 20	2	< 20	< 10	< 30	17	1.6	< 5	65
Sample 11	Granodiorite	6	1	36	< 20	6	< 20	< 10	40	16	1.5	< 5	68
Sample 12	Granodiorite	6	1	36	< 20	6	< 20	10	50	18	1.6	< 5	68
Sample 13	Granodiorite	6	1	40	< 20	7	< 20	< 10	40	17	1.4	< 5	51
Sample 14	Granodiorite	6	1	35	< 20	6	< 20	< 10	40	16	1.7	< 5	81
Sample 15	Mafic Dyke	20	2	186	30	26	30	70	90	18	1.5	< 5	67
		Y (ppm)	Zr (ppm)	Nb (ppm)	Mo (ppm)	Ag (ppm)	In (ppm)	Sn (ppm)	Sb (ppm)	Cs (ppm)	Ba (ppm)	La (ppm)	Ce (ppm)
Sample 1	Granodiorite	18.8	178	5.9	< 2	1.3	< 0.1	1	< 0.2	0.5	531	52	75.4
Sample 2	Granodiorite	8.2	223	7.3	< 2	1.5	< 0.1	2	< 0.2	0.6	461	15.5	45.5
Sample 6	Mafic Dyke	16.4	105	4.2	< 2	0.7	< 0.1	< 1	< 0.2	0.5	980	18.7	39.5
Sample 7	Mafic Dyke	18.1	116	4.6	< 2	0.8	< 0.1	< 1	< 0.2	0.6	1,222	22.8	43.4
Sample 8	Mafic Dyke	15.3	119	3.9	< 2	0.8	< 0.1	1	< 0.2	0.8	924	20.3	42.8
Sample 9	Granodiorite	9.3	85	7.5	< 2	< 0.5	< 0.1	2	< 0.2	0.4	499	13.4	24.2
Sample 10	Meta Rhyolite	16.1	170	8.4	< 2	1.1	< 0.1	1	< 0.2	1.5	511	34.3	66.6
Sample 11	Granodiorite	15.7	201	7.1	< 2	1.4	< 0.1	1	0.4	1.2	511	30.7	59
Sample 12	Granodiorite	16.5	203	7.3	< 2	1.4	< 0.1	1	0.3	1.4	489	29.9	56.6
Sample 13	Granodiorite	15.7	183	6.4	< 2	1.2	< 0.1	1	< 0.2	0.4	550	31.1	59.4
Sample 14	Granodiorite	15.2	217	7.1	< 2	1.4	< 0.1	1	0.6	1.8	535	30.6	58.7
Sample 15	Mafic Dyke	20.1	148	5.7	< 2	1.1	< 0.1	1	< 0.2	1	1,251	31.8	66.1
		Nd (ppm)	Sm (ppm)	Eu (ppm)	Gd (ppm)	Tb (ppm)	Dy (ppm)	Ho (ppm)	Er (ppm)	Tm (ppm)	Yb (ppm)	Lu (ppm)	Hf (ppm)
Sample 1	Granodiorite	35.5	5.29	1.1	4.3	0.61	3.29	0.66	1.86	0.273	1.82	0.286	4.1
Sample 2	Granodiorite	12.6	2.25	0.638	1.52	0.27	1.7	0.34	1.02	0.173	1.34	0.217	5
Sample 6	Mafic Dyke	22.5	5.01	1.39	4.24	0.63	3.36	0.64	1.72	0.243	1.78	0.246	2.5
Sample 7	Mafic Dyke	24.4	5.02	1.52	4.37	0.64	3.58	0.68	1.89	0.251	1.69	0.257	2.7
Sample 8	Mafic Dyke	23	5.1	1.35	3.96	0.59	3.27	0.61	1.66	0.232	1.52	0.242	3
Sample 9	Granodiorite	10.1	1.9	0.248	1.47	0.23	1.48	0.32	1.02	0.186	1.44	0.254	3.1
Sample 10	Meta Rhyolite	27.7	4.78	1.3	3.59	0.56	3.15	0.6	1.66	0.241	1.62	0.239	4.1
Sample 11	Granodiorite	23.2	4.09	0.823	3.14	0.48	2.87	0.59	1.69	0.266	1.92	0.288	4.9
Sample 12	Granodiorite	23.1	3.78	0.918	3.34	0.51	2.82	0.58	1.7	0.263	1.77	0.261	4.4
Sample 13	Granodiorite	24	4.08	0.966	3.24	0.51	2.84	0.56	1.69	0.258	1.74	0.27	4.4
Sample 14	Granodiorite	22.5	4.1	0.893	2.97	0.48	2.83	0.58	1.73	0.26	1.76	0.278	4.9
Sample 15	Mafic Dyke	34.9	7.47	1.88	5.61	0.8	4.15	0.76	2.02	0.287	1.89	0.293	3.5
		W (ppm)	Tl (ppm)	Pb (ppm)	Bi (ppm)	Th (ppm)	U (ppm)	Sr (ppm)	Pr (ppm)	Ta (ppm)
Sample 1	Granodiorite	< 0.5	0.19	5	< 0.1	5.67	1.06	227	10.5	0.63
Sample 2	Granodiorite	0.7	0.16	7	< 0.1	6.12	1.07	205	3.59	1.33
Sample 6	Mafic Dyke	< 0.5	0.21	10	< 0.1	4.38	1.4	460	5.18	0.29
Sample 7	Mafic Dyke	< 0.5	0.46	10	< 0.1	3.66	1.31	498	5.87	0.36
Sample 8	Mafic Dyke	< 0.5	0.3	12	0.1	4.38	1.38	425	5.55	0.28
Sample 9	Granodiorite	< 0.5	0.36	12	< 0.1	11.9	3.73	65	3.03	1.7
Sample 10	Meta Rhyolite	< 0.5	0.27	7	< 0.1	5.23	1.37	195	7.56	0.89
Sample 11	Granodiorite	34.9	0.28	6	< 0.1	6.23	1.63	106	6.59	0.92
Sample 12	Granodiorite	15.1	0.21	6	< 0.1	5.7	1.61	146	6.48	0.66
Sample 13	Granodiorite	< 0.5	0.24	6	< 0.1	5.51	1.44	256	6.78	0.73
Sample 14	Granodiorite	14	0.3	< 5	< 0.1	5.44	1.42	105	6.54	0.78
Sample 15	Mafic Dyke	< 0.5	0.35	13	< 0.1	5.43	1.78	705	8.5	0.43

[1] *Corresponding author.

Brasil

Brasil

The 9 Mile Deposit of the Barama-Mazaruni Greenstone Belt of the Guiana Shield: geochemistry, geochronology and regional significance

ABSTRACT: