Origin and Tectonic Implications of the Eocene Granite from the Gongshan Block in Northwest Yunnan Province

Abstract

Abstract:

Paleogene granite developed in the Sanjiang area,Yunnan Province, which records magmatism information during the collision between Indian and Asian continents. Integrated geochemistry and zircon U-Pb-Hf isotopic analyses were carried out on the granite in the Gongshan block. Results show that the granite is I-S type with calc-alkaline, peraluminous features. Zircon U-Pb isotopic analyses show that the granite emplaced at 55 Ma with 252-77 Ma inherited zircon grains in it. Magmatic zircons from the granite in the Gongshan show resemblance Hf isotope compositions with those from coveal felsic intrusions in the Lhasa block of Tibetan Plateau and its extended southeastern margin, implying their similar magmatic origin. The mixing calculation results under constraints of isotopic and trace element compositions confirm that the primary magma of the Eocene granite in the study area originate from the partial melting (5%-15%) of mixed protolith between juvenile crust material (53%) and Mesoproterozoic crustal basement component (47%). Similarities of the Eocene granite in the Gongshan block and the coeval Gangdese block and Tengchong block in geochemical features imply their common petrogenesis. We suggest that the Eocene granite in the Gongshan block was most likely derived from intra-crustal decompressional melting related to breakoff of the Neo-Tethyan oceanic slab during post-collision.

Key words: Sanjiang area, Gongshan block, granite, zircon U-Pb-Hf isotope, Yunnan Province

CLC Number:

P588.1
P597

KANG Huan, QING Xingquan, CHEN Yuelong, LI Dapeng, LU Zhen, HU Guoqiang, DENG Weibing. Origin and Tectonic Implications of the Eocene Granite from the Gongshan Block in Northwest Yunnan Province[J]. Geoscience, 2017, 31(06): 1177-1186.

Figures/Tables 11

Fig.1 Geological map of the Sanjiang area of western Yunnan Province and the sampling position

Fig.2 Outcrop of the Maji granite

Fig.3 Micrographs of the Maji granite

Table 1 Whole-rock chemical compositions of gneissic granite from the Gongshan Block

样品	SiO₂	TiO₂	Al₂O₃	Fe₂O₃	MnO	MgO	CaO	Na₂O	K₂O	P₂O₅	烧失量	总量	Nb
NJ-5-1	71.31	0.42	11.57	4.21	0.12	0.4	0.52	3.88	4.95	0.06	0.19	97.64	91
样品	Cs	Ba	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er
NJ-5-1	5	179	94.6	233	28.2	107	21.6	1.51	18.66	3.62	19.1	3.67	10.7
样品	Tm	Li	Be	Sc	V	Cr	Co	Ni	Cu	Zn	Ga	Ge	Rb
NJ-5-1	1.4	80.4	8.43	12.6	3.27	5.95	0.72	4.24	9.29	335	34	2	198
样品	Sr	Y	Zr	Yb	Lu	Hf	Ta	W	Tl	Pb	Bi	Th	U
NJ-5-1	19.5	75	451	8.73	1.19	13.6	8.48	0.62	0.73	23.4	0.15	23.3	5.67

Fig.4 Chondrite-normalized REE (a) and primitive mantle-normalized trace element (b) patterns of the granite from the Gongshan Block

Fig.5 Zircon U-Pb ages and the image of zircon of the gneissic granite from the Gongshan Block

Table 2 The LA-ICP-MS zircon U-Pb dating results of gneissic granite from the Gongshan Block

点号	U	Th	Th/U	同位素比值				年龄/Ma					谐和度/%
点号	U	Th	Th/U	²⁰⁷Pb/ ²⁰⁶Pb	²⁰⁷Pb/ ²³⁵U	²⁰⁶Pb/ ²³⁸U	1σ	²⁰⁷Pb/ ²⁰⁶Pb	1σ	²⁰⁷Pb/ ²³⁵U	²⁰⁶Pb/ ²³⁸U	1σ	谐和度/%
NJ-5-1-1	333	40	0.12	0.049 05	0.081 80	0.012 17	0.000 09	150	100	80	78	1	97
NJ-5-1-2	202	91	0.45	0.049 25	0.149 13	0.021 94	0.000 13	167	105	141	140	1	99
NJ-5-1-3	222	43	0.19	0.049 13	0.104 74	0.015 43	0.000 09	154	115	101	99	1	97
NJ-5-1-4	188	144	0.77	0.051 63	0.250 15	0.035 18	0.000 18	333	54	227	223	1	98
NJ-5-1-5	288	198	0.69	0.049 88	0.154 04	0.022 43	0.000 21	191	108	145	143	1	98
NJ-5-1-6	328	211	0.64	0.051 61	0.197 27	0.027 76	0.000 16	333	57	183	177	1	96
NJ-5-1-7	306	70	0.23	0.049 04	0.151 38	0.022 35	0.000 20	150	53	143	143	1	99
NJ-5-1-8	481	119	0.25	0.050 08	0.187 47	0.027 14	0.000 16	198	56	174	173	1	98
NJ-5-1-9	146	24	0.16	0.048 04	0.090 10	0.013 42	0.000 16	102	226	88	86	1	98
NJ-5-1-10	350	143	0.41	0.049 63	0.164 38	0.024 03	0.000 11	176	8	155	153	1	99
NJ-5-1-11	354	128	0.36	0.049 67	0.186 61	0.027 30	0.000 14	189	54	174	174	1	99
NJ-5-1-12	266	173	0.65	0.049 09	0.154 88	0.022 81	0.000 14	154	70	146	145	1	99
NJ-5-1-13	194	56	0.29	0.047 83	0.080 87	0.012 22	0.000 07	100	135	79	78	0	99
NJ-5-1-14	333	79	0.24	0.048 63	0.101 58	0.015 16	0.000 07	132	77	98	97	0	98
NJ-5-1-15	112	33	0.30	0.050 29	0.061 90	0.008 62	0.000 14	209	356	61	55	1	90
NJ-5-1-16	212	41	0.20	0.052 78	0.246 78	0.033 81	0.000 27	320	46	224	214	2	95
NJ-5-1-17	293	394	1.35	0.053 03	0.292 47	0.040 02	0.000 26	332	32	261	253	2	97
NJ-5-1-18	331	94	0.28	0.051 12	0.131 61	0.018 72	0.000 21	256	98	126	120	1	95
NJ-5-1-19	267	46	0.17	0.048 62	0.091 27	0.013 56	0.000 13	128	144	89	87	1	97
NJ-5-1-20	156	49	0.31	0.048 29	0.066 72	0.009 72	0.000 31	122	246	66	62	2	94
NJ-5-1-21	221	20	0.09	0.048 85	0.083 68	0.012 36	0.000 12	139	106	82	79	1	97
NJ-5-1-22	481	63	0.13	0.052 42	0.224 86	0.031 07	0.000 30	306	22	206	197	2	95
NJ-5-1-23	298	64	0.22	0.050 50	0.107 23	0.015 33	0.000 19	217	55	103	98	1	94

Table 2 The LA-ICP-MS zircon U-Pb dating results of gneissic granite from the Gongshan Block

点号	U	Th	Th/U	同位素比值				年龄/Ma					谐和度/%
点号	U	Th	Th/U	²⁰⁷Pb/ ²⁰⁶Pb	²⁰⁷Pb/ ²³⁵U	²⁰⁶Pb/ ²³⁸U	1σ	²⁰⁷Pb/ ²⁰⁶Pb	1σ	²⁰⁷Pb/ ²³⁵U	²⁰⁶Pb/ ²³⁸U	1σ	谐和度/%
NJ-5-1-1	333	40	0.12	0.049 05	0.081 80	0.012 17	0.000 09	150	100	80	78	1	97
NJ-5-1-2	202	91	0.45	0.049 25	0.149 13	0.021 94	0.000 13	167	105	141	140	1	99
NJ-5-1-3	222	43	0.19	0.049 13	0.104 74	0.015 43	0.000 09	154	115	101	99	1	97
NJ-5-1-4	188	144	0.77	0.051 63	0.250 15	0.035 18	0.000 18	333	54	227	223	1	98
NJ-5-1-5	288	198	0.69	0.049 88	0.154 04	0.022 43	0.000 21	191	108	145	143	1	98
NJ-5-1-6	328	211	0.64	0.051 61	0.197 27	0.027 76	0.000 16	333	57	183	177	1	96
NJ-5-1-7	306	70	0.23	0.049 04	0.151 38	0.022 35	0.000 20	150	53	143	143	1	99
NJ-5-1-8	481	119	0.25	0.050 08	0.187 47	0.027 14	0.000 16	198	56	174	173	1	98
NJ-5-1-9	146	24	0.16	0.048 04	0.090 10	0.013 42	0.000 16	102	226	88	86	1	98
NJ-5-1-10	350	143	0.41	0.049 63	0.164 38	0.024 03	0.000 11	176	8	155	153	1	99
NJ-5-1-11	354	128	0.36	0.049 67	0.186 61	0.027 30	0.000 14	189	54	174	174	1	99
NJ-5-1-12	266	173	0.65	0.049 09	0.154 88	0.022 81	0.000 14	154	70	146	145	1	99
NJ-5-1-13	194	56	0.29	0.047 83	0.080 87	0.012 22	0.000 07	100	135	79	78	0	99
NJ-5-1-14	333	79	0.24	0.048 63	0.101 58	0.015 16	0.000 07	132	77	98	97	0	98
NJ-5-1-15	112	33	0.30	0.050 29	0.061 90	0.008 62	0.000 14	209	356	61	55	1	90
NJ-5-1-16	212	41	0.20	0.052 78	0.246 78	0.033 81	0.000 27	320	46	224	214	2	95
NJ-5-1-17	293	394	1.35	0.053 03	0.292 47	0.040 02	0.000 26	332	32	261	253	2	97
NJ-5-1-18	331	94	0.28	0.051 12	0.131 61	0.018 72	0.000 21	256	98	126	120	1	95
NJ-5-1-19	267	46	0.17	0.048 62	0.091 27	0.013 56	0.000 13	128	144	89	87	1	97
NJ-5-1-20	156	49	0.31	0.048 29	0.066 72	0.009 72	0.000 31	122	246	66	62	2	94
NJ-5-1-21	221	20	0.09	0.048 85	0.083 68	0.012 36	0.000 12	139	106	82	79	1	97
NJ-5-1-22	481	63	0.13	0.052 42	0.224 86	0.031 07	0.000 30	306	22	206	197	2	95
NJ-5-1-23	298	64	0.22	0.050 50	0.107 23	0.015 33	0.000 19	217	55	103	98	1	94

Table 3 The Hf isotope component results of zircons from the Gongshan Block gneissic granite

分析点	t/Ma	¹⁷⁶Yb/¹⁷⁷Hf	¹⁷⁶Lu/¹⁷⁷Hf	¹⁷⁶Hf/¹⁷⁷Hf	±2σ	ε_Hf(0)	ε_Hf(t)	$T D M C$ /Ga
NJ-5-1-1	78	0.030 401	0.000 499	0.282 782	0.000 021	0.34	2.02	1.0
NJ-5-1-4	223	0.042 639	0.000 644	0.282 787	0.000 020	0.54	5.34	0.9
NJ-5-1-6	177	0.072 429	0.001 638	0.282 857	0.000 022	2.99	6.68	0.8
NJ-5-1-7	143	0.092 090	0.002 092	0.282 794	0.000 020	0.77	3.71	1.0
NJ-5-1-8	173	0.092 345	0.001 998	0.282 815	0.000 021	1.53	5.09	0.9
NJ-5-1-15	55	0.025 197	0.000 518	0.282 849	0.000 018	2.73	3.92	0.9
NJ-5-1-18	120	0.145 100	0.002 585	0.282 802	0.000 022	1.07	3.49	1.0
NJ-5-1-21	79	0.020 340	0.000 366	0.282 792	0.000 020	0.71	2.43	1.0
NJ-5-1-22	197	0.066 343	0.001 192	0.282 856	0.000 022	2.96	7.14	0.8
NJ-5-1-23	98	0.029 849	0.000 416	0.282 733	0.000 018	-1.37	0.75	1.1

Table 3 The Hf isotope component results of zircons from the Gongshan Block gneissic granite

分析点	t/Ma	¹⁷⁶Yb/¹⁷⁷Hf	¹⁷⁶Lu/¹⁷⁷Hf	¹⁷⁶Hf/¹⁷⁷Hf	±2σ	ε_Hf(0)	ε_Hf(t)	$T D M C$ /Ga
NJ-5-1-1	78	0.030 401	0.000 499	0.282 782	0.000 021	0.34	2.02	1.0
NJ-5-1-4	223	0.042 639	0.000 644	0.282 787	0.000 020	0.54	5.34	0.9
NJ-5-1-6	177	0.072 429	0.001 638	0.282 857	0.000 022	2.99	6.68	0.8
NJ-5-1-7	143	0.092 090	0.002 092	0.282 794	0.000 020	0.77	3.71	1.0
NJ-5-1-8	173	0.092 345	0.001 998	0.282 815	0.000 021	1.53	5.09	0.9
NJ-5-1-15	55	0.025 197	0.000 518	0.282 849	0.000 018	2.73	3.92	0.9
NJ-5-1-18	120	0.145 100	0.002 585	0.282 802	0.000 022	1.07	3.49	1.0
NJ-5-1-21	79	0.020 340	0.000 366	0.282 792	0.000 020	0.71	2.43	1.0
NJ-5-1-22	197	0.066 343	0.001 192	0.282 856	0.000 022	2.96	7.14	0.8
NJ-5-1-23	98	0.029 849	0.000 416	0.282 733	0.000 018	-1.37	0.75	1.1

Fig.6 The εHf(t) vs.U-Pb age plot of the gneissic granite from the Gongshan Block

Table 4 The simulation results of the partial melting

元素	母体成分 C₀/10^-6	总分配系数 (D)	F=0.01 浓度/10^-6	F=0.1 浓度/10^-6	实际浓度/ 10^-6
Ce	36.18	0.09	351.52	196.11	233.00
Nd	16.47	0.12	128.79	79.51	107.00
Sm	3.84	0.18	19.94	14.44	21.60
Eu	1.06	0.37	3.35	2.80	1.51
Gd	4.12	0.28	14.38	11.72	18.66
Yb	2.62	1.32	1.99	2.04	8.73

Fig.7 The rare earth element distribution patterns of partial melting in diagenetic model

References 46

[1]	METCALFE I. Gondwana dispersion and Asian accretion: Tectonic and palaeogeographic evolution of eastern Tethys[J]. Journal of Asian Earth Sciences, 2013, 66: 1-33. DOI URL
[2]	YIN A, HARRISON T M. Geologic evolution of the Himalayan-Tibetan orogen[J]. Annual Review of Earth and Planetary Sciences, 2000, 28: 211-280. DOI URL
[3]	康欢, 李大鹏, 陈岳龙, 等. 云南保山东缘早古生代高Si花岗岩的成因及构造意义[J]. 现代地质, 2016, 30(5): 1026-1037.
[4]	WANG Y J, ZHANG A M, FAN W M, et al. Petrogenesis of late Triassic post-collisional basaltic rocks of the Lancangjiang tectonic zone, southwest China, and tectonic implications for the evolution of the eastern Paleotethys: Geochronological and geochemical constraints[J]. Lithos, 2010, 120(3/4): 529-546. DOI URL
[5]	董方浏, 侯增谦, 高永丰, 等. 滇西腾冲新生代花岗岩:成因类型与构造意义[J]. 岩石学报, 2006, 22(4): 927-937.
[6]	杨启军, 徐义刚, 黄小龙, 等. 滇西腾冲—梁河地区花岗岩的年代学、地球化学及其构造意义[J]. 岩石学报, 2009, 25(5): 1092-1104.
[7]	黄玉, 赵志丹, 张凤琴, 等. 西藏冈底斯仁布—拉萨一带花岗岩基的地球化学及其意义[J]. 岩石学报, 2010, 26(10): 3131-3142.
[8]	XU Y G, YANG Q J, LAN J B, et al. Temporal-spatial distribution and tectonic implications of the batholiths in the Gaoligong-Tengliang-Yingjiang area, western Yunnan: Constraints from zircon U-Pb ages and Hf isotopes[J]. Journal of Asian Earth Sciences, 2012, 53: 151-175. DOI URL
[9]	莫宣学, 董国臣, 赵志丹, 等. 西藏冈底斯带花岗岩的时空分布特征及地壳生长演化信息[J]. 高校地质学报, 2005, 11(3): 281-290.
[10]	董国臣, 莫宣学, 赵志丹, 等. 冈底斯岩浆带中段岩浆混合作用:来自花岗杂岩的证据[J]. 岩石学报, 2006, 22(4): 835-844.
[11]	季建清. 滇西南腾冲—盈江—那邦地区岩石学与新生代岩石圈构造演化[D]. 北京: 中国科学院地质与地球物理研究所, 1998: 1-88.
[12]	SONG S G, NIU Y L, WEI C J, et al. Metamorphism, anatexis, zircon ages and tectonic evolution of the Gongshan block in the northern Indochina continent—An eastern extension of the Lhasa Block[J]. Lithos, 2010, 120(3/4): 327-346. DOI URL
[13]	李再会, 林仕良, 丛峰, 等. 滇西高黎贡山群变质岩的锆石年龄及其构造意义[J]. 岩石学报, 2012, 28(5): 183-195.
[14]	董美玲, 董国臣, 莫宣学, 等. 滇西保山地块早古生代花岗岩类的年代学、地球化学及意义[J]. 岩石学报, 2012, 28(5): 107-118.
[15]	LI D P, CHEN Y L, HOU K J, et al. Detrital zircon record of Paleozoic and Mesozoic meta-sedimentary strata in the eastern part of the Baoshan block: Implications of their provenance and the tectonic evolution of the southeastern margin of the Tibetan plateau[J]. Lithos, 2015, 227: 194-204. DOI URL
[16]	云南省地质矿产局. 云南省区域地质志[M]. 北京: 地质出版社, 1990: 1-730.
[17]	宋彪, 张玉海, 万渝生, 等. 锆石SHRIMP样品靶制作、年龄测定及有关现象讨论[J]. 地质论评, 2002, 48(S1): 26-30.
[18]	SLÁMA J, KOŠLER J, CONDON D J, et al. Plešovice zircon — A new natural reference material for U-Pb and Hf isotopic microanalysis[J]. Chemical Geology, 2008, 249(1/2): 1-35. DOI URL
[19]	LUDWIG K R. Isoplot/Ex Version 3.0: A Geochronological Toolkit for Microsoft Excel[M]. Berkeley: Berkeley Geochronology Center, 2003: 1-30.
[20]	WU F Y, YANG Y H, XIE L W, et al. Hf isotopic compositions of the standard zircons and baddeleyites used in U-Pb geochronology[J]. Chemical Geology, 2006, 234(1/2): 105-126. DOI URL
[21]	侯可军, 李延河, 邹天人, 等. LA-MC-ICP-MS锆石Hf同位素的分析方法及地质应用[J]. 岩石学报, 2007, 23(10): 2595-2604.
[22]	赵志丹, 朱弟成, 董国臣, 等. 西藏当雄南部约54Ma辉长岩-花岗岩杂岩的岩石成因及意义[J]. 岩石学报, 2011, 27(12): 3513-3524.
[23]	高永娟, 林仕良, 丛峰, 等. 滇西腾冲—梁河古近纪花岗岩锆石U-Pb定年、Hf同位素及地球化学[J]. 岩石学报, 2014, 88(1): 63-71.
[24]	BOYNTON W V. Cosmochemistry of the rare earth elements: Meteorite studies[J]. Developments in Geochemistry, 1984, 2(2): 63-114.
[25]	SUN S S, MCDONOUGH W F. Chemical and isotopic systematics of oceanic basalts; implications for mantle composition and processes[J]. Geological Society of London Special Publications, 1989, 42(1): 313-345. DOI URL
[26]	HOSKIN P W O. The composition of zircon and igneous and metamorphic petrogenesis[J]. Reviews in Mineralogy and Geochemistry, 2003, 53(1): 27-62. DOI URL
[27]	侯增谦, 郑远川, 杨志明, 等. 大陆碰撞成矿作用:Ⅰ. 冈底斯新生代斑岩成矿系统[J]. 矿床地质, 2012, 31(4): 647-670.
[28]	马莉燕, 范蔚茗, 王岳军, 等. 那邦地区花岗片麻岩的锆石U-Pb年代学及Hf同位素组成特征[J]. 大地构造与成矿学, 2013, 37(2): 273-283.
[29]	吕伯西. 中华人民共和国地质矿产部地质专报: 三江地区花岗岩类及其成矿专属性[M]. 北京: 地质出版社, 1993:1-330.
[30]	丛峰, 林仕良, 谢韬, 等. 滇西腾冲—梁河地区花岗岩锆石稀土元素组成和U-Pb同位素年龄[J]. 吉林大学学报(地球科学版), 2010, 40(3): 573-580.
[31]	唐渊, 王冬兵, 廖世勇, 等. 滇西高黎贡变质岩带南段淡色花岗岩脉年代学特征及构造意义[J]. 岩石学报, 2016, 32(8): 2347-2366.
[32]	HARRIS N B W, XU R, LEWIS C L, et al. The geological evolution of Tibet-Plutonic Rocks of the 1985 Tibet Geotraverse, Lhasa to Golmud[J]. Philosophical Transactions of the Royal Society of London, 1988, 327: 145-168.
[33]	王立强, 林鑫, 李壮, 等. 西藏蒙亚啊铅锌矿区花岗斑岩年代学、地球化学及Hf同位素组成特征[J]. 地质学报, 2014, 88(12): 2572-2583.
[34]	XU W C, ZHANG H F, HARRIS N, et al, Geochronology and geochemistry of Mesoproterozoic granitoids in the Lhasa terrane, South Tibet: implications for Mid-Ocean Ridge subduction and crustal growth[J]. Precambrian Research, 2013, 236(5):46-58. DOI URL
[35]	管琪, 朱弟成, 赵志丹, 等. 西藏拉萨地块南缘晚白垩世镁铁质岩浆作用的年代学、地球化学及意义[J]. 岩石学报, 2011, 27(7): 2083-2094.
[36]	张德会, 赵仑山. 地球化学[M]. 北京: 地质出版社, 2013:1-364.
[37]	VERVOORT J D, PATCHETT P J, BLICHERT-TOFT J, et al. Relationships between Lu-Hf and Sm-Nd isotopic systems in the global sedimentary system[J]. Earth and Planetary Science Letters, 1999, 168(1/2):79-99. DOI URL
[38]	于炳松, 赵志丹, 苏尚国. 岩石学[M]. 北京: 地质出版社, 2012: 1-275.
[39]	刘飞, 陈岳龙, 蒋丽婷. MATLAB在碎屑沉积岩矿物含量计算中的应用[J]. 沉积学报, 2006, 24(2): 229-234.
[40]	赵振华. 微量元素地球化学原理[M]. 北京: 科学出版社, 1997: 1-238.
[41]	罗茂澄, 王立强, 冷秋锋, 等. 邦铺钼(铜)矿床二长花岗斑岩、黑云二长花岗岩锆石Hf同位素和Ce⁴⁺/Ce³⁺比值[J]. 矿床地质, 2011, 30(2): 266-278.
[42]	林进展, 曹华文, 张寿庭, 等. 青藏高原东南缘腾冲来利山A型花岗岩地球化学特征、锆石U-Pb定年及其构造意义[J]. 大地构造与成矿学, 2015(5): 959-971.
[43]	莫宣学, 赵志丹, 邓晋福, 等. 印度—亚洲大陆主碰撞过程的火山作用响应[J]. 地学前缘, 2003, 10(3): 135-148.
[44]	王成善, 李祥辉, 胡修棉. 再论印度—亚洲大陆碰撞的启动时间[J]. 地质学报, 2003, 77(1): 16-24.
[45]	ROWLEY D B. Age of initiation of collision between India and Asia: A review of stratigraphic data[J]. Earth and Planetary Science Letters, 1996, 145(1/4): 1-13. DOI URL
[46]	李皓扬, 钟孙霖, 王彦斌, 等. 藏南林周盆地林子宗火山岩的时代、成因及其地质意义:锆石U-Pb年龄和Hf同位素证据[J]. 岩石学报, 2007, 23(2): 493-500.