Formation Time of the Northeastern Jiangxi Ophiolite in the Eastern Jiangnan Orogenic Belt:Evidence from LA-ICP-MS Zircon U-Pb Dating of the Gabbro

Abstract

Abstract:

Proterozoic Ophiolite of the eastern Jiangnan orogenic belt in Northeastern Jiangxi was mainly composed of serpentinized ultramafic rock, cumulated rock, isotropic gabbro and diabase, low-temperature and high-pressure blueschist and plagiogranite. LA-ICP-MS zircon U-Pb dating for one gabbro sample from the Northeastern Jiangxi Ophiolite yielded a ²⁰⁷Pb/²⁰⁶Pb age of (992±25) Ma (MSWD=1.19), which represented the intrusion time of the gabbro. The geochronological result suggests the existence of Early Proterozoic palaeo-oceanic basin in the southeastern Yangtze block, which is younger than the late Meso-Proterozoic oceanic basin in the northern margin of the Yangtze block. Therefore, it is proposed that the Meso-Neoproterozoic crystallization basement rocks in the Yangtze craton were formed in a gradually aggregated process with characteristics of trending from northwest to southeast direction.

Key words: Jiangnan orogenic belt, Northeastern Jiangxi Ophiolite, gabbro, zircon U-Pb dating, Early Neoproterozoic

CLC Number:

P588.12

JIANG Xingfu, PENG Songbai, KUSKY Timothy, WANG Lu, DENG Hao, WANG Junpeng. Formation Time of the Northeastern Jiangxi Ophiolite in the Eastern Jiangnan Orogenic Belt:Evidence from LA-ICP-MS Zircon U-Pb Dating of the Gabbro[J]. Geoscience, 2017, 31(04): 697-704.

Figures/Tables 9

References 42

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点号	²⁰⁴Pb/ 10^-6	²³²Th/ 10^-6	²³⁸U/ 10^-6	Th/U	校正后同位素比值					校正后表面年龄/Ma
点号	²⁰⁴Pb/ 10^-6	²³²Th/ 10^-6	²³⁸U/ 10^-6	Th/U	²⁰⁷Pb/ ²³⁵U	1σ	²⁰⁶Pb/ ²³⁸U	1σ		²⁰⁷Pb/ ²⁰⁶Pb		1σ	²⁰⁷Pb/ ²³⁵U		1σ		²⁰⁶Pb/ ²³⁸U		1σ
01	63.60	184	279	0.66	1.741 3	0.054 7	0.182 2	0.002 2	876		65			1 024		20		1 079		12
02	42.43	104	203	0.51	1.634 6	0.047 9	0.173 9	0.001 7	854		67			984		18		1 033		9
03	39.70	95	187	0.51	1.804 7	0.058 9	0.178 4	0.002 0	994		65			1 047		21		1 058		11
04	41.20	113	196	0.58	1.782 4	0.052 6	0.173 4	0.001 8	1 037		63			1 039		19		1 031		10
05	45.50	134	220	0.61	1.765 2	0.054 2	0.172 9	0.001 9	1 017		65			1 033		20		1 028		11
06	36.93	101	174	0.58	1.758 2	0.058 4	0.174 2	0.002 2	998		69			1 030		22		1 035		12
07	69.60	157	316	0.50	1.874 0	0.052 2	0.171 7	0.001 8	1 139		53			1 072		18		1 022		10
08	37.73	113	179	0.63	1.599 7	0.043 8	0.159 5	0.001 6	972		56			970		17		954		9
09	47.10	169	218	0.78	1.555 6	0.036 5	0.155 2	0.001 6	987		44			953		15		930		9
10	54.80	157	265	0.59	1.478 7	0.031 8	0.146 1	0.001 2	1 000		39			922		13		879		7
11	161.80	241	625	0.39	1.710 4	0.034 0	0.178 2	0.001 5	903		64			1 012		13		1 057		8
12	132.50	223	527	0.42	1.667 8	0.032 8	0.170 3	0.001 4	948		31			996		12		1 014		7
13	129.50	273	484	0.56	1.763 8	0.042 4	0.178 5	0.001 8	965		44			1 032		16		1 059		10
14	150.50	249	588	0.42	1.694 9	0.040 4	0.172 4	0.001 5	967		48			1 007		15		1 025		8
15	84.80	143	348	0.41	1.644 4	0.046 3	0.165 9	0.001 7	987		64			987		18		989		9
16	133.70	197	521	0.38	1.787 1	0.048 3	0.178 4	0.001 9	994		55			1 041		18		1 058		10
17	127.60	270	479	0.56	1.836 7	0.045 6	0.177 9	0.001 7	1 057		50			1 059		16		1 056		9
18	177.80	481	712	0.68	1.696 5	0.037 4	0.166 4	0.001 5	1 029		44			1 007		14		992		8
19	131.30	313	534	0.59	1.676 8	0.042 9	0.168 9	0.001 5	974		52			1 000		16		1 006		8
20	112.10	223	462	0.48	1.775 0	0.051 5	0.173 1	0.001 7	1 039		55			1 036		19		1 029		10
21	127.30	240	527	0.46	1.891 0	0.060 9	0.183 9	0.002 4	1 035		61			1 078		21		1 088		13
22	198.70	658	757	0.87	1.804 0	0.049 6	0.176 2	0.001 7	1 033		56			1 047		18		1 046		9
23	222.90	726	909	0.80	1.751 4	0.045 2	0.172 5	0.001 9	1 009		47			1 028		17		1 026		11
24	238.90	512	999	0.51	1.775 0	0.045 1	0.177 1	0.001 8	983		51			1 036		17		1 051		10
25	104.00	202	455	0.44	1.732 8	0.048 3	0.172 3	0.001 7	985		56			1 021		18		1 025		9

点号	²⁰⁴Pb/ 10^-6	²³²Th/ 10^-6	²³⁸U/ 10^-6	Th/U	校正后同位素比值					校正后表面年龄/Ma
点号	²⁰⁴Pb/ 10^-6	²³²Th/ 10^-6	²³⁸U/ 10^-6	Th/U	²⁰⁷Pb/ ²³⁵U	1σ	²⁰⁶Pb/ ²³⁸U	1σ		²⁰⁷Pb/ ²⁰⁶Pb		1σ	²⁰⁷Pb/ ²³⁵U		1σ		²⁰⁶Pb/ ²³⁸U		1σ
01	63.60	184	279	0.66	1.741 3	0.054 7	0.182 2	0.002 2	876		65			1 024		20		1 079		12
02	42.43	104	203	0.51	1.634 6	0.047 9	0.173 9	0.001 7	854		67			984		18		1 033		9
03	39.70	95	187	0.51	1.804 7	0.058 9	0.178 4	0.002 0	994		65			1 047		21		1 058		11
04	41.20	113	196	0.58	1.782 4	0.052 6	0.173 4	0.001 8	1 037		63			1 039		19		1 031		10
05	45.50	134	220	0.61	1.765 2	0.054 2	0.172 9	0.001 9	1 017		65			1 033		20		1 028		11
06	36.93	101	174	0.58	1.758 2	0.058 4	0.174 2	0.002 2	998		69			1 030		22		1 035		12
07	69.60	157	316	0.50	1.874 0	0.052 2	0.171 7	0.001 8	1 139		53			1 072		18		1 022		10
08	37.73	113	179	0.63	1.599 7	0.043 8	0.159 5	0.001 6	972		56			970		17		954		9
09	47.10	169	218	0.78	1.555 6	0.036 5	0.155 2	0.001 6	987		44			953		15		930		9
10	54.80	157	265	0.59	1.478 7	0.031 8	0.146 1	0.001 2	1 000		39			922		13		879		7
11	161.80	241	625	0.39	1.710 4	0.034 0	0.178 2	0.001 5	903		64			1 012		13		1 057		8
12	132.50	223	527	0.42	1.667 8	0.032 8	0.170 3	0.001 4	948		31			996		12		1 014		7
13	129.50	273	484	0.56	1.763 8	0.042 4	0.178 5	0.001 8	965		44			1 032		16		1 059		10
14	150.50	249	588	0.42	1.694 9	0.040 4	0.172 4	0.001 5	967		48			1 007		15		1 025		8
15	84.80	143	348	0.41	1.644 4	0.046 3	0.165 9	0.001 7	987		64			987		18		989		9
16	133.70	197	521	0.38	1.787 1	0.048 3	0.178 4	0.001 9	994		55			1 041		18		1 058		10
17	127.60	270	479	0.56	1.836 7	0.045 6	0.177 9	0.001 7	1 057		50			1 059		16		1 056		9
18	177.80	481	712	0.68	1.696 5	0.037 4	0.166 4	0.001 5	1 029		44			1 007		14		992		8
19	131.30	313	534	0.59	1.676 8	0.042 9	0.168 9	0.001 5	974		52			1 000		16		1 006		8
20	112.10	223	462	0.48	1.775 0	0.051 5	0.173 1	0.001 7	1 039		55			1 036		19		1 029		10
21	127.30	240	527	0.46	1.891 0	0.060 9	0.183 9	0.002 4	1 035		61			1 078		21		1 088		13
22	198.70	658	757	0.87	1.804 0	0.049 6	0.176 2	0.001 7	1 033		56			1 047		18		1 046		9
23	222.90	726	909	0.80	1.751 4	0.045 2	0.172 5	0.001 9	1 009		47			1 028		17		1 026		11
24	238.90	512	999	0.51	1.775 0	0.045 1	0.177 1	0.001 8	983		51			1 036		17		1 051		10
25	104.00	202	455	0.44	1.732 8	0.048 3	0.172 3	0.001 7	985		56			1 021		18		1 025		9

点号	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu
01	0	18.0	0	0	0.9	0.6	6.0	3.3	53.5	28	162	46	556	135
02	0	12.0	0	0.4	0.2	0.6	5.5	3.1	45.8	23	140	43	543	137
03	0.5	10.2	0	0.3	1.1	0.3	4.6	2.4	40.1	21	123	37	468	117
04	0	10.9	0	0.5	0.5	0.2	4.6	2.1	35.8	18	102	30	357	84
05	0	13.1	0.2	1.0	2.2	0.5	7.9	3.5	54.5	26	157	47	576	142
06	0.1	9.8	0	0	1.8	0.4	4.0	1.7	29.4	14	81	24	283	66
07	0.1	17.9	0	0.1	0.4	0.4	10.3	3.9	64.2	34	203	61	734	178
08	0	12.5	0	0.5	0	0.5	7.8	2.5	41.0	21	123	37	456	113
09	0	17.1	0	0	0.7	0.5	7.7	3.0	48.2	23	131	38	432	98
10	0	12.4	0	0.8	1.2	0.5	9.2	4.1	64.9	31	182	54	631	151
11	0	13.0	0.1	0.6	0.8	0.3	10.1	4.0	62.4	31	182	56	677	156
12	0	11.5	0.1	0	1.2	0.8	6.6	3.9	60.2	30	174	51	620	145
13	0	14.5	0.1	1.0	1.2	0.5	11.0	4.9	69.3	33	189	54	641	148
14	0	12.6	0.1	0	1.4	0.4	9.9	4.3	62.6	31	183	53	646	152
15	0.2	10.6	0	0.6	0.6	0.4	6.0	2.8	43.3	22	129	40	498	118
16	0	15.2	0.1	0.7	0.9	0.6	8.4	3.8	59.1	30	177	54	658	159
17	0	16.0	0	0.3	1.7	0.1	6.8	3.1	45.8	22	126	35	416	95
18	0	20.2	0	0	1.4	0.8	8.5	4.0	59.4	28	156	45	516	114
19	0	21.0	0.1	1.1	1.6	0.7	8.0	3.8	57.6	28	160	46	532	120
20	0.1	13.3	0	0.8	1.6	0.4	8.5	4.1	62.4	30	178	53	642	147
21	0.1	22.4	0	1.0	1.3	0.3	11.1	4.6	76.0	39	236	71	853	199
22	0	25.8	0	0.5	1.1	0.8	10.3	4.6	67.9	33	185	52	588	130
23	0	38.0	0.2	0.9	2.1	0.6	15.4	7.2	105.5	50	274	76	856	186
24	0.1	19.8	0.1	0.3	2.9	0.3	19.0	9.8	142.6	70	403	116	1 372	306
25	0.1	20.6	0	1.2	0.4	0.8	11.1	4.8	72.7	36	221	67	842	189

点号	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu
01	0	18.0	0	0	0.9	0.6	6.0	3.3	53.5	28	162	46	556	135
02	0	12.0	0	0.4	0.2	0.6	5.5	3.1	45.8	23	140	43	543	137
03	0.5	10.2	0	0.3	1.1	0.3	4.6	2.4	40.1	21	123	37	468	117
04	0	10.9	0	0.5	0.5	0.2	4.6	2.1	35.8	18	102	30	357	84
05	0	13.1	0.2	1.0	2.2	0.5	7.9	3.5	54.5	26	157	47	576	142
06	0.1	9.8	0	0	1.8	0.4	4.0	1.7	29.4	14	81	24	283	66
07	0.1	17.9	0	0.1	0.4	0.4	10.3	3.9	64.2	34	203	61	734	178
08	0	12.5	0	0.5	0	0.5	7.8	2.5	41.0	21	123	37	456	113
09	0	17.1	0	0	0.7	0.5	7.7	3.0	48.2	23	131	38	432	98
10	0	12.4	0	0.8	1.2	0.5	9.2	4.1	64.9	31	182	54	631	151
11	0	13.0	0.1	0.6	0.8	0.3	10.1	4.0	62.4	31	182	56	677	156
12	0	11.5	0.1	0	1.2	0.8	6.6	3.9	60.2	30	174	51	620	145
13	0	14.5	0.1	1.0	1.2	0.5	11.0	4.9	69.3	33	189	54	641	148
14	0	12.6	0.1	0	1.4	0.4	9.9	4.3	62.6	31	183	53	646	152
15	0.2	10.6	0	0.6	0.6	0.4	6.0	2.8	43.3	22	129	40	498	118
16	0	15.2	0.1	0.7	0.9	0.6	8.4	3.8	59.1	30	177	54	658	159
17	0	16.0	0	0.3	1.7	0.1	6.8	3.1	45.8	22	126	35	416	95
18	0	20.2	0	0	1.4	0.8	8.5	4.0	59.4	28	156	45	516	114
19	0	21.0	0.1	1.1	1.6	0.7	8.0	3.8	57.6	28	160	46	532	120
20	0.1	13.3	0	0.8	1.6	0.4	8.5	4.1	62.4	30	178	53	642	147
21	0.1	22.4	0	1.0	1.3	0.3	11.1	4.6	76.0	39	236	71	853	199
22	0	25.8	0	0.5	1.1	0.8	10.3	4.6	67.9	33	185	52	588	130
23	0	38.0	0.2	0.9	2.1	0.6	15.4	7.2	105.5	50	274	76	856	186
24	0.1	19.8	0.1	0.3	2.9	0.3	19.0	9.8	142.6	70	403	116	1 372	306
25	0.1	20.6	0	1.2	0.4	0.8	11.1	4.8	72.7	36	221	67	842	189