Geochemical Characteristics and Tectonic Implications of Gabbro in Mayigangri Area, Tibet

Abstract

Abstract:

The intrusive dikes in Mayigangri area of Tibet are gabbros. Based on the micrograph of the gabbrosamples, the contents of major elements, trace elements and REEs are measured. The results show that the rocks are characterized by an enrichment of LREE, and a depletion of HREE. There is no positive or negative Eu anomaly. The gabbro are enriched in Hf, La, Nd and Ti, and are depleted in P, Yb, Y and other elements. The geochemical features indicate that the gabbros are generated in an intracontinental rift environment; and the magma is derived from enriched mantle with a contamination of salic crust materials. Combined with the fact that gabbro surrounding rocks are Late Paleozoic low metamorphic rock series and undeveloped dike swarms in strata after late Early Permian, and based on the age restrictions that the basic dike swarms in south part of northern Qiangtang is formed from Late Carboniferous to Early Permian by the predecessors, it is deduced that the gabbro is the product that paleo-Tethys ocean in this region opened initially.

Key words: Mayigangri, gabbro, geochemistry, Tibet

CLC Number:

P588

CUI Yuliang, WANG Genhou, LIANG Xiao. Geochemical Characteristics and Tectonic Implications of Gabbro in Mayigangri Area, Tibet[J]. Geoscience, 2017, 31(02): 258-266.

Figures/Tables 11

References 41

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样品号	SiO₂	Al₂O₃	TiO₂	Fe₂O₃	FeO	CaO	MgO	K₂O	Na₂O	MnO	P₂O₅	烧失量	总量
M01-1	44.32	12.08	5.16	5.83	11.29	8.74	5.19	1.18	2.52	0.19	0.22	2.97	99.69
M01-2	42.94	11.37	5.48	6.96	11.35	9.60	5.46	0.94	2.26	0.195	0.22	2.98	99.76
M01-3	43.99	11.70	5.47	6.82	10.79	8.92	5.02	1.06	2.50	0.215	0.26	3.01	99.75
M01-4	47.31	12.86	4.38	4.90	9.83	8.72	4.24	0.83	3.29	0.176	0.28	2.93	99.74
M01-5	49.86	11.38	1.60	2.98	6.88	12.34	9.37	0.50	1.36	0.135	0.13	3.19	99.73
M02-1	47.42	12.68	1.29	2.53	6.10	14.06	10.39	0.61	1.32	0.119	0.10	3.13	99.73
M02-2	47.33	14.18	1.35	2.92	5.44	13.40	9.24	0.90	1.70	0.123	0.12	3.09	99.79
M02-3	48.15	11.63	1.36	3.21	5.28	13.03	11.28	0.50	1.82	0.118	0.09	3.28	99.74
M02-4	47.73	12.42	1.98	3.75	7.15	11.69	8.67	1.13	1.84	0.156	0.16	3.07	99.76
M02-5	47.42	13.07	1.77	3.20	6.34	12.14	9.42	1.09	1.65	0.132	0.14	3.40	99.78
样品号	Mg^#	Pb	Li	Rb	Cs	Mo	Sr	Ba	Sc	Nb	Ta	Zr	Hf
M01-1	19.51	3.50	22.18	63.6	43.49	1.09	320.7	439.3	30.28	27.86	1.73	184.9	5.39
M01-2	19.31	3.34	18.58	46.3	75.70	1.13	251.4	323.3	29.45	26.52	1.63	179.1	5.38
M01-3	18.63	4.27	20.82	50.7	72.68	1.25	292.4	426.0	30.51	28.99	1.85	195.6	5.71
M01-4	18.68	4.65	17.20	24.0	42.17	0.93	292.1	445.2	25.52	25.92	1.63	212.2	6.31
M01-5	43.07	16.13	47.46	17.7	2.03	0.67	364.9	281.0	32.82	10.26	0.75	110.4	3.87
M02-1	48.93	5.35	35.10	22.5	9.65	0.38	508.3	193.9	33.59	7.79	0.56	95.8	3.40
M02-2	46.89	4.01	29.81	25.5	5.61	0.42	389.7	230.1	28.40	7.56	0.55	92.7	3.13
M02-3	51.58	13.96	40.86	13.9	9.71	0.61	458.0	206.4	35.84	10.57	0.16	98.4	3.60
M02-4	38.87	15.10	31.06	40.9	13.55	0.57	286.3	292.2	28.67	16.25	1.04	135.4	4.46
M02-5	44.07	6.68	33.73	34.3	10.04	0.42	250.2	397.4	29.40	13.18	0.90	122.0	4.02
样品号	U	Th	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er
M01-1	1.07	5.27	20.69	49.19	6.73	28.87	7.12	2.26	6.57	1.3	6.96	1.28	3.59
M01-2	0.83	3.72	19.72	45.67	6.21	26.96	6.71	2.23	6.15	1.18	6.66	1.24	3.37
M01-3	1.03	4.51	21.35	49.72	6.77	28.82	7.06	2.18	6.53	1.24	7.03	1.29	3.53
M01-4	1.08	4.56	23.69	54.90	7.38	31.82	7.60	2.31	6.79	1.3	7.14	1.3	3.58
M01-5	0.56	2.64	12.71	28.85	3.85	16.65	4.18	1.39	3.78	0.78	4.31	0.8	2.24
M02-1	0.54	2.22	10.09	23.12	3.15	13.76	3.56	1.23	3.17	0.64	3.54	0.65	1.83
M02-2	0.48	1.79	8.41	19.49	2.67	11.80	3.02	1.02	2.65	0.52	2.9	0.53	1.47
M02-3	1.11	2.16	9.52	22.04	3.04	13.18	3.27	1.17	3	0.61	3.43	0.62	1.72
M02-4	0.69	3.22	16.97	38.21	5.24	22.38	5.47	1.72	4.88	0.94	5.25	0.96	2.68
M02-5	0.76	3.06	16.38	36.84	4.90	20.67	5.11	1.71	4.48	0.87	4.79	0.86	2.44
样品号	Tm	Yb	Lu	Y	ΣREE	LREE	HREE	LREE/HREE		(La/Yb)_N		δCe	δEu
M01-1	0.57	3.09	0.65	33.72	138.87	114.86	24.01	4.78		4.80		1.02	0.99
M01-2	0.52	2.78	0.61	31.33	130.01	107.50	22.51	4.77		5.09		1.00	1.04
M01-3	0.57	3.09	0.66	32.89	139.84	115.90	23.93	4.84		4.96		1.01	0.97
M01-4	0.55	3.02	0.64	33.87	152.02	127.70	24.32	5.25		5.63		1.01	0.96
M01-5	0.34	1.89	0.36	20.5	82.13	67.62	14.51	4.66		4.83		1.00	1.05
M02-1	0.28	1.48	0.3	16.36	66.81	54.92	11.89	4.62		4.89		1.00	1.09
M02-2	0.23	1.17	0.24	13.36	56.13	46.41	9.72	4.77		5.14		1.00	1.08
M02-3	0.28	1.45	0.29	15.66	63.63	52.22	11.41	4.58		4.70		1.00	1.12
M02-4	0.43	2.26	0.49	23.85	107.87	89.99	17.89	5.03		5.39		0.99	1.00
M02-5	0.38	2.08	0.43	21.99	101.95	85.61	16.34	5.24		5.66		1.00	1.06

样品号	SiO₂	Al₂O₃	TiO₂	Fe₂O₃	FeO	CaO	MgO	K₂O	Na₂O	MnO	P₂O₅	烧失量	总量
M01-1	44.32	12.08	5.16	5.83	11.29	8.74	5.19	1.18	2.52	0.19	0.22	2.97	99.69
M01-2	42.94	11.37	5.48	6.96	11.35	9.60	5.46	0.94	2.26	0.195	0.22	2.98	99.76
M01-3	43.99	11.70	5.47	6.82	10.79	8.92	5.02	1.06	2.50	0.215	0.26	3.01	99.75
M01-4	47.31	12.86	4.38	4.90	9.83	8.72	4.24	0.83	3.29	0.176	0.28	2.93	99.74
M01-5	49.86	11.38	1.60	2.98	6.88	12.34	9.37	0.50	1.36	0.135	0.13	3.19	99.73
M02-1	47.42	12.68	1.29	2.53	6.10	14.06	10.39	0.61	1.32	0.119	0.10	3.13	99.73
M02-2	47.33	14.18	1.35	2.92	5.44	13.40	9.24	0.90	1.70	0.123	0.12	3.09	99.79
M02-3	48.15	11.63	1.36	3.21	5.28	13.03	11.28	0.50	1.82	0.118	0.09	3.28	99.74
M02-4	47.73	12.42	1.98	3.75	7.15	11.69	8.67	1.13	1.84	0.156	0.16	3.07	99.76
M02-5	47.42	13.07	1.77	3.20	6.34	12.14	9.42	1.09	1.65	0.132	0.14	3.40	99.78
样品号	Mg^#	Pb	Li	Rb	Cs	Mo	Sr	Ba	Sc	Nb	Ta	Zr	Hf
M01-1	19.51	3.50	22.18	63.6	43.49	1.09	320.7	439.3	30.28	27.86	1.73	184.9	5.39
M01-2	19.31	3.34	18.58	46.3	75.70	1.13	251.4	323.3	29.45	26.52	1.63	179.1	5.38
M01-3	18.63	4.27	20.82	50.7	72.68	1.25	292.4	426.0	30.51	28.99	1.85	195.6	5.71
M01-4	18.68	4.65	17.20	24.0	42.17	0.93	292.1	445.2	25.52	25.92	1.63	212.2	6.31
M01-5	43.07	16.13	47.46	17.7	2.03	0.67	364.9	281.0	32.82	10.26	0.75	110.4	3.87
M02-1	48.93	5.35	35.10	22.5	9.65	0.38	508.3	193.9	33.59	7.79	0.56	95.8	3.40
M02-2	46.89	4.01	29.81	25.5	5.61	0.42	389.7	230.1	28.40	7.56	0.55	92.7	3.13
M02-3	51.58	13.96	40.86	13.9	9.71	0.61	458.0	206.4	35.84	10.57	0.16	98.4	3.60
M02-4	38.87	15.10	31.06	40.9	13.55	0.57	286.3	292.2	28.67	16.25	1.04	135.4	4.46
M02-5	44.07	6.68	33.73	34.3	10.04	0.42	250.2	397.4	29.40	13.18	0.90	122.0	4.02
样品号	U	Th	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er
M01-1	1.07	5.27	20.69	49.19	6.73	28.87	7.12	2.26	6.57	1.3	6.96	1.28	3.59
M01-2	0.83	3.72	19.72	45.67	6.21	26.96	6.71	2.23	6.15	1.18	6.66	1.24	3.37
M01-3	1.03	4.51	21.35	49.72	6.77	28.82	7.06	2.18	6.53	1.24	7.03	1.29	3.53
M01-4	1.08	4.56	23.69	54.90	7.38	31.82	7.60	2.31	6.79	1.3	7.14	1.3	3.58
M01-5	0.56	2.64	12.71	28.85	3.85	16.65	4.18	1.39	3.78	0.78	4.31	0.8	2.24
M02-1	0.54	2.22	10.09	23.12	3.15	13.76	3.56	1.23	3.17	0.64	3.54	0.65	1.83
M02-2	0.48	1.79	8.41	19.49	2.67	11.80	3.02	1.02	2.65	0.52	2.9	0.53	1.47
M02-3	1.11	2.16	9.52	22.04	3.04	13.18	3.27	1.17	3	0.61	3.43	0.62	1.72
M02-4	0.69	3.22	16.97	38.21	5.24	22.38	5.47	1.72	4.88	0.94	5.25	0.96	2.68
M02-5	0.76	3.06	16.38	36.84	4.90	20.67	5.11	1.71	4.48	0.87	4.79	0.86	2.44
样品号	Tm	Yb	Lu	Y	ΣREE	LREE	HREE	LREE/HREE		(La/Yb)_N		δCe	δEu
M01-1	0.57	3.09	0.65	33.72	138.87	114.86	24.01	4.78		4.80		1.02	0.99
M01-2	0.52	2.78	0.61	31.33	130.01	107.50	22.51	4.77		5.09		1.00	1.04
M01-3	0.57	3.09	0.66	32.89	139.84	115.90	23.93	4.84		4.96		1.01	0.97
M01-4	0.55	3.02	0.64	33.87	152.02	127.70	24.32	5.25		5.63		1.01	0.96
M01-5	0.34	1.89	0.36	20.5	82.13	67.62	14.51	4.66		4.83		1.00	1.05
M02-1	0.28	1.48	0.3	16.36	66.81	54.92	11.89	4.62		4.89		1.00	1.09
M02-2	0.23	1.17	0.24	13.36	56.13	46.41	9.72	4.77		5.14		1.00	1.08
M02-3	0.28	1.45	0.29	15.66	63.63	52.22	11.41	4.58		4.70		1.00	1.12
M02-4	0.43	2.26	0.49	23.85	107.87	89.99	17.89	5.03		5.39		0.99	1.00
M02-5	0.38	2.08	0.43	21.99	101.95	85.61	16.34	5.24		5.66		1.00	1.06