Geochemistry and petrogenesis of Miocene dikes in the Shigatse area, southern Tibet

doi:10.13745/j.esf.sf.2025.10.57

Abstract

Abstract:

Dikes are small-scale intrusions with mineral compositions similar to those of contemporaneous magmatic rocks. The Miocene dikes in the southern Gangdese exhibit diverse modes and ages, recording information pertaining to both magmatism and tectonics. This study focuses on dikes in Xaitongmoin County, Shigatse, combining geochemistry, geochronology, and Lu-Hf isotopes to elucidate their petrogenesis, structural characteristics, source properties, and geodynamic implications. Zircon U-Pb dating indicates that the dikes were emplaced between 15.2 and 14.5 Ma, identifying them as post-collisional Miocene intrusions. Geochemically, these dikes exhibit high MgO, high Mg^#, and elevated concentrations of incompatible elements. They also show adakitic characteristics, including high Sr, low Y and Yb, high Sr/Y ratios, enrichment in light rare earth elements (LREE) and large ion lithophile elements (LILE), and depletion in heavy rare earth elements (HREE) and high field strength elements (HFSE). Based on integrated geochemical and structural features, we propose a genetic model: delamination of the lower crust triggered gravitational collapse of the southern Lhasa terrane, leading to superimposed N-S and E-W extensional structures. The delaminated lower crust underwent partial melting upon reaching the asthenosphere and incorporated mantle components. The resulting melts ascended along the normal faults and rifts formed by extension, ultimately forming the Shigatse diorite porphyry dikes with two spatial orientations emplaced in close temporal proximity.

Key words: Gangdise batholith, South Lhasa Block, Miocene, dike rocks, adakitic rocks

CLC Number:

LI Lichan, ZHAO Zhidan, TANG Yan, LIU Dong, WANG Zhenzhen, WANG Qing, ZHU Dicheng, MO Xuanxue. Geochemistry and petrogenesis of Miocene dikes in the Shigatse area, southern Tibet[J]. Earth Science Frontiers, 2025, 32(6): 377-395.

Figures/Tables 14

Fig.1 Magmatic structure map of Lhasa terrane and geological map of the study area. a modified after [9]; b adapted from [39].

Fig.2 Lithostratigraphic section and lithological characteristics of the Shigatse diorite porphyry dikes

Fig.3 Microscopic photographs of the Shigatse diorite porphyry dikes

Table 1 Whole-rock major and trace element data of the Shigatse diorite porphyry dikes

样品	w_B/%
样品	SiO₂			TiO₂			Al₂O₃			Fe₂O₃			MnO			MgO			CaO			Na₂O			K₂O			P₂O₅		LOI
XT2101	56.9			0.78			16.6			6.08			0.08			3.97			5.79			4.14			1.27			0.27		3.96
XT2109	56.8			0.72			16.8			6.62			0.08			4.38			5.87			4.46			1.67			0.29		1.89
XT2113	58.2			0.63			15.8			5.62			0.1			4.76			5.48			4.41			1.82			0.2		2.72
XT2116	56.6			0.63			15.6			5.76			0.09			4.81			5.25			4.96			2.07			0.2		3.74
样品	w_B/10^-6
样品	Li			Be			Sc			V			Cr			Co			Ni			Cu			Zn			Ga		Rb
XT2101	28.13			1.42			11.71			150.2			77.56			19.79			62.96			31.36			59.46			20.73		35.28
XT2109	16.97			1.75			12.02			134.7			78.04			22.1			77.2			65.16			48.41			20		29.4
XT2113	10.03			1.43			13.45			125.4			163.73			20.54			91.27			9.5			45.88			18.75		36.3
XT2116	25.94			1.22			13.81			129			178.65			23.48			95.93			16.61			54.21			18.72		50.68
样品		w_B/10^-6
样品		Sr	Y			Zr			Nb			Sn			Cs		Ba			La			Ce			Pr			Nd
XT2101		830	11.23			95.61			4.34			1.45			3.61		447.5			18.9			40.9			5.04			21.4
XT2109		1202	12.16			112.11			5.08			0.83			0.6		741.2			26.7			56.2			7.02			28.4
XT2113		737.9	11.39			85.72			4.17			0.7			0.7		562.4			13.9			29.6			3.71			15.3
XT2116		784.2	11.44			94			3.69			0.79			1.31		488			14.7			31			3.84			15.8
样品		w_B/10^-6
样品		Sm	Eu			Gd			Tb			Dy			Ho		Er			Tm			Yb			Lu			Hf
XT2101		4.12	1.08			3.11			0.41			2.09			0.4		1.01			0.13			0.89			0.12			2.78
XT2109		4.78	1.33			3.37			0.44			2.25			0.41		1.12			0.16			1.06			0.16			3.13
XT2113		3.1	0.86			2.51			0.4			2			0.42		1.14			0.16			1.02			0.16			2.52
XT2116		3.18	0.82			2.43			0.38			2.02			0.44		1.16			0.17			1			0.17			2.67
样品		w_B/10^-6
样品		Ta			Tl			Pb			Th			U				ΣREE			Sr/Y			δEu			(La/Yb)_N				Y/Yb
XT2101		0.25			0.25			7.65			3.73			0.82				99.58			73.88			0.88			15.24				12.6
XT2109		0.29			0.23			8.62			5.69			1.1				133.44			98.88			0.96			18.1				11.48
XT2113		0.29			0.21			5.66			3.7			0.57				74.38			64.79			0.92			9.84				11.21
XT2116		0.26			0.29			9.95			3.58			0.75				77.04			68.56			0.86			10.48				11.38

Fig.4 Whole rock major element classification diagrams of Shigatse diorite porphyry dikes. Base map adapted from [39].

Fig.5 Whole rock rare earth element and incompatible element distribution diagrams of Shigatse diorite porphyry dikes. Standardized values adapted from [43].

Table2 U-Pb age data of the Shigatse diorite porphyry dikes

Table 3 Hafnium isotopic compositions of zircons of the Shigatse diorite porphyry dikes

测点号	¹⁷⁶Yb/¹⁷⁷Hf	2σ	¹⁷⁶Lu/¹⁷⁷Hf	2σ	¹⁷⁶Hf/¹⁷⁷Hf	2σ	Age/Ma	ε_Hf(t)	T_DM/Ma	$T D M C$ /Ma
XT2101 01	0.030 550	0.000 460	0.001 340	0.000 024	0.283 063	0.000 029	14.7	13.7	270	322
XT2101 02	0.020 170	0.000 590	0.000 944	0.000 026	0.283 073	0.000 038	14.7	12.0	253	354
XT2101 03	0.022 000	0.000 400	0.000 923	0.000 017	0.283 048	0.000 023	14.7	13.5	288	344
XT2101 04	0.006 450	0.000 850	0.000 274	0.000 034	0.283 060	0.000 024	14.7	14.0	266	312
XT2101 06	0.027 470	0.000 970	0.001 179	0.000 030	0.283 090	0.000 024	14.7	14.7	230	259
XT2101 07	0.030 680	0.000 330	0.001 186	0.000 012	0.282 898	0.000 035	14.7	4.3	504	793
XT2101 08	0.026 080	0.000 420	0.001 085	0.000 016	0.282 916	0.000 033	14.7	4.9	477	753
XT2101 09	0.012 900	0.000 330	0.000 610	0.000 016	0.282 863	0.000 023	14.7	3.1	546	872
XT2101 10	0.015 950	0.000 350	0.000 735	0.000 016	0.283 038	0.000 025	14.7	12.6	301	382
XT2101 11	0.022 030	0.000 650	0.000 876	0.000 025	0.283 020	0.000 024	14.7	10.0	327	477
XT2101 12	0.018 710	0.000 970	0.000 767	0.000 031	0.282 944	0.000 041	14.7	5.9	434	690
XT2101 13	0.014 220	0.000 230	0.000 549	0.000 010	0.282 873	0.000 022	14.7	3.4	531	850
XT2101 15	0.026 260	0.000 590	0.001 026	0.000 020	0.283 038	0.000 018	14.7	10.6	303	439
XT2101 17	0.048 600	0.001 700	0.001 571	0.000 055	0.282 749	0.000 025	14.7	-0.5	724	1118
XT2101 18	0.017 770	0.000 360	0.000 759	0.000 011	0.282 863	0.000 021	14.7	3.1	548	872
XT2109 01	0.038 980	0.000 400	0.001 682	0.000 016	0.283 024	0.000 032	14.7	12.2	329	416
XT2109 02	0.056 120	0.000 810	0.002 039	0.000 028	0.282 919	0.000 026	14.7	5.1	485	746
XT2109 03	0.033 200	0.001 200	0.001 196	0.000 034	0.282 885	0.000 026	14.7	3.8	523	823
XT2109 04	0.047 490	0.000 310	0.001 799	0.000 015	0.283 040	0.000 027	14.7	10.7	306	435
XT2109 05	0.139 240	0.000 910	0.004 528	0.000 021	0.283 058	0.000 020	14.7	11.0	303	406
XT2109 06	0.068 600	0.001 300	0.002 685	0.000 050	0.283 053	0.000 023	14.7	11.1	295	409
XT2109 07	0.012 630	0.000 220	0.000 537	0.000 008	0.282 876	0.000 027	14.7	3.5	526	843
XT2109 08	0.034 201	0.000 610	0.001 294	0.000 017	0.282 810	0.000 027	14.7	1.9	631	974
XT2109 09	0.027 900	0.001 400	0.001 153	0.000 060	0.283 050	0.000 021	14.7	13.1	287	354
XT2109 10	0.019 310	0.000 780	0.000 758	0.000 021	0.282 879	0.000 024	14.7	3.6	525	836
XT2109 11	0.013 470	0.000 120	0.000 545	0.000 005	0.282 866	0.000 021	14.7	3.1	541	867
XT2109 12	0.031 500	0.002 500	0.001 194	0.000 083	0.283 038	0.000 032	14.7	10.6	304	440
XT2109 13	0.045 550	0.000 830	0.001 555	0.000 022	0.282 910	0.000 025	14.7	4.7	492	767
XT2109 14	0.063 600	0.001 400	0.002 421	0.000 052	0.283 078	0.000 026	14.7	11.9	255	354
XT2109 15	0.067 900	0.001 200	0.002 442	0.000 042	0.282 985	0.000 029	14.7	7.4	393	596
XT2109 16	0.044 400	0.002 400	0.001 421	0.000 076	0.282 903	0.000 022	14.7	4.5	500	782
XT2109 17	0.066 500	0.001 400	0.002 437	0.000 045	0.283 059	0.000 021	14.7	11.3	284	395
XT2109 18	0.021 700	0.000 270	0.000 831	0.000 008	0.282 879	0.000 023	14.7	3.7	526	835
XT2113 01	0.039 540	0.000 580	0.001 534	0.000 020	0.283 101	0.000 020	14.5	12.9	216	294
XT2113 02	0.021 630	0.000 290	0.000 750	0.000 008	0.282 764	0.000 020	14.5	-0.4	687	1096
XT2113 03	0.052 080	0.000 200	0.001 742	0.000 009	0.282 886	0.000 022	14.5	3.9	529	821
XT2113 04	0.059 000	0.000 660	0.002 005	0.000 019	0.282 930	0.000 019	14.5	5.4	469	721
XT2113 05	0.057 330	0.000 510	0.002 039	0.000 022	0.282 924	0.000 022	14.5	5.2	478	735
XT2113 06	0.067 280	0.000 580	0.002 440	0.000 025	0.282 957	0.000 026	14.5	6.4	435	660
XT2113 07	0.061 650	0.000 550	0.002 091	0.000 012	0.282 921	0.000 022	14.5	5.1	483	741
XT2113 08	0.040 210	0.000 100	0.001 389	0.000 005	0.282 921	0.000 021	14.5	5.1	474	741
XT2113 09	0.044 200	0.001 100	0.001 571	0.000 047	0.282 991	0.000 025	14.5	7.6	375	583
XT2113 10	0.028 704	0.000 039	0.001 141	0.000 001	0.283 055	0.000 019	14.5	13.3	280	342
XT2113 11	0.037 800	0.001 100	0.001 569	0.000 045	0.283 047	0.000 018	14.5	13.1	294	359
XT2113 12	0.034 540	0.000 390	0.001 423	0.000 014	0.283 054	0.000 022	14.5	13.3	283	344
XT2113 13	0.035 900	0.000 790	0.001 471	0.000 034	0.283 042	0.000 024	14.5	13.0	301	368
XT2113 14	0.021 480	0.000 360	0.000 910	0.000 013	0.283 059	0.000 024	14.5	13.4	272	333
XT2113 15	0.048 140	0.000 800	0.001 993	0.000 021	0.283 062	0.000 022	14.5	13.6	276	327
XT2113 16	0.029 160	0.000 380	0.001 203	0.000 013	0.283 064	0.000 025	14.5	13.7	267	318
测点号	¹⁷⁶Yb/¹⁷⁷Hf	2σ	¹⁷⁶Lu/¹⁷⁷Hf	2σ	¹⁷⁶Hf/¹⁷⁷Hf	2σ	Age/Ma	ε_Hf(t)	T_DM/Ma	$T D M C$ /Ma
XT2113 17	0.030 010	0.000 410	0.001 204	0.000 018	0.283 064	0.000 019	14.5	13.8	267	317
XT2113 18	0.028 320	0.000 170	0.001 197	0.000 007	0.283 038	0.000 019	14.5	12.8	304	379
XT2113 19	0.029 950	0.000 840	0.001 200	0.000 033	0.283 062	0.000 023	14.5	13.5	270	327
XT2113 20	0.015 976	0.000 062	0.000 687	0.000 003	0.283 039	0.000 025	14.5	13.1	299	366
XT2113 21	0.027 390	0.000 360	0.001 144	0.000 014	0.283 056	0.000 022	14.5	13.5	278	336
XT2113 22	0.049 290	0.000 360	0.001 810	0.000 011	0.282 939	0.000 021	14.5	5.8	453	700
XT2113 23	0.052 340	0.000 200	0.001 751	0.000 004	0.282 924	0.000 019	14.5	5.2	474	734
XT2113 24	0.061 190	0.000 240	0.002 158	0.000 015	0.282 948	0.000 021	14.5	6.1	444	680
XT2116 01	0.054 280	0.000 470	0.002 087	0.000 013	0.282 953	0.000 024	15.2	6.3	436	668
XT2116 02	0.039 700	0.001 000	0.001 486	0.000 041	0.282 952	0.000 030	15.2	6.3	431	670
XT2116 03	0.016 500	0.001 000	0.000 636	0.000 036	0.282 854	0.000 029	15.2	2.8	559	893
XT2116 04	0.028 870	0.000 860	0.001 115	0.000 034	0.282 924	0.000 022	15.2	5.2	466	735
XT2116 05	0.010 560	0.000 310	0.000 407	0.000 010	0.282 893	0.000 019	15.2	4.2	501	801
XT2116 06	0.027 650	0.000 250	0.001 034	0.000 013	0.282 905	0.000 023	15.2	4.6	492	777
XT2116 07	0.027 590	0.000 320	0.001 138	0.000 009	0.283 021	0.000 049	15.2	8.6	328	515
XT2116 08	0.008 250	0.000 110	0.000 338	0.000 003	0.282 875	0.000 020	15.2	3.4	525	847
XT2116 09	0.039 460	0.000 460	0.001 554	0.000 017	0.282 879	0.000 021	15.2	3.7	537	835
XT2116 10	0.014 920	0.000 260	0.000 583	0.000 008	0.282 849	0.000 020	15.2	2.6	565	904
XT2116 11	0.031 100	0.000 630	0.001 151	0.000 021	0.282 918	0.000 027	15.2	5.0	475	748
XT2116 12	0.028 430	0.000 170	0.001 166	0.000 005	0.282 890	0.000 027	15.2	4.0	515	811
XT2116 13	0.031 120	0.000 560	0.001 195	0.000 013	0.282 890	0.000 026	15.2	4.0	516	812
XT2116 14	0.039 980	0.000 950	0.001 471	0.000 042	0.282 907	0.000 024	15.2	4.7	495	772
XT2116 15	0.016 610	0.000 250	0.000 678	0.000 007	0.282 880	0.000 026	15.2	3.8	523	831
XT2116 16	0.018 960	0.000 210	0.000 759	0.000 009	0.282 887	0.000 025	15.2	3.9	514	818
XT2116 17	0.017 200	0.000 130	0.000 674	0.000 004	0.282 894	0.000 021	15.2	4.0	503	807
XT2116 18	0.016 920	0.000 340	0.000 628	0.000 013	0.282 887	0.000 022	15.2	4.0	512	816

Table 3 Hafnium isotopic compositions of zircons of the Shigatse diorite porphyry dikes

测点号	¹⁷⁶Yb/¹⁷⁷Hf	2σ	¹⁷⁶Lu/¹⁷⁷Hf	2σ	¹⁷⁶Hf/¹⁷⁷Hf	2σ	Age/Ma	ε_Hf(t)	T_DM/Ma	$T D M C$ /Ma
XT2101 01	0.030 550	0.000 460	0.001 340	0.000 024	0.283 063	0.000 029	14.7	13.7	270	322
XT2101 02	0.020 170	0.000 590	0.000 944	0.000 026	0.283 073	0.000 038	14.7	12.0	253	354
XT2101 03	0.022 000	0.000 400	0.000 923	0.000 017	0.283 048	0.000 023	14.7	13.5	288	344
XT2101 04	0.006 450	0.000 850	0.000 274	0.000 034	0.283 060	0.000 024	14.7	14.0	266	312
XT2101 06	0.027 470	0.000 970	0.001 179	0.000 030	0.283 090	0.000 024	14.7	14.7	230	259
XT2101 07	0.030 680	0.000 330	0.001 186	0.000 012	0.282 898	0.000 035	14.7	4.3	504	793
XT2101 08	0.026 080	0.000 420	0.001 085	0.000 016	0.282 916	0.000 033	14.7	4.9	477	753
XT2101 09	0.012 900	0.000 330	0.000 610	0.000 016	0.282 863	0.000 023	14.7	3.1	546	872
XT2101 10	0.015 950	0.000 350	0.000 735	0.000 016	0.283 038	0.000 025	14.7	12.6	301	382
XT2101 11	0.022 030	0.000 650	0.000 876	0.000 025	0.283 020	0.000 024	14.7	10.0	327	477
XT2101 12	0.018 710	0.000 970	0.000 767	0.000 031	0.282 944	0.000 041	14.7	5.9	434	690
XT2101 13	0.014 220	0.000 230	0.000 549	0.000 010	0.282 873	0.000 022	14.7	3.4	531	850
XT2101 15	0.026 260	0.000 590	0.001 026	0.000 020	0.283 038	0.000 018	14.7	10.6	303	439
XT2101 17	0.048 600	0.001 700	0.001 571	0.000 055	0.282 749	0.000 025	14.7	-0.5	724	1118
XT2101 18	0.017 770	0.000 360	0.000 759	0.000 011	0.282 863	0.000 021	14.7	3.1	548	872
XT2109 01	0.038 980	0.000 400	0.001 682	0.000 016	0.283 024	0.000 032	14.7	12.2	329	416
XT2109 02	0.056 120	0.000 810	0.002 039	0.000 028	0.282 919	0.000 026	14.7	5.1	485	746
XT2109 03	0.033 200	0.001 200	0.001 196	0.000 034	0.282 885	0.000 026	14.7	3.8	523	823
XT2109 04	0.047 490	0.000 310	0.001 799	0.000 015	0.283 040	0.000 027	14.7	10.7	306	435
XT2109 05	0.139 240	0.000 910	0.004 528	0.000 021	0.283 058	0.000 020	14.7	11.0	303	406
XT2109 06	0.068 600	0.001 300	0.002 685	0.000 050	0.283 053	0.000 023	14.7	11.1	295	409
XT2109 07	0.012 630	0.000 220	0.000 537	0.000 008	0.282 876	0.000 027	14.7	3.5	526	843
XT2109 08	0.034 201	0.000 610	0.001 294	0.000 017	0.282 810	0.000 027	14.7	1.9	631	974
XT2109 09	0.027 900	0.001 400	0.001 153	0.000 060	0.283 050	0.000 021	14.7	13.1	287	354
XT2109 10	0.019 310	0.000 780	0.000 758	0.000 021	0.282 879	0.000 024	14.7	3.6	525	836
XT2109 11	0.013 470	0.000 120	0.000 545	0.000 005	0.282 866	0.000 021	14.7	3.1	541	867
XT2109 12	0.031 500	0.002 500	0.001 194	0.000 083	0.283 038	0.000 032	14.7	10.6	304	440
XT2109 13	0.045 550	0.000 830	0.001 555	0.000 022	0.282 910	0.000 025	14.7	4.7	492	767
XT2109 14	0.063 600	0.001 400	0.002 421	0.000 052	0.283 078	0.000 026	14.7	11.9	255	354
XT2109 15	0.067 900	0.001 200	0.002 442	0.000 042	0.282 985	0.000 029	14.7	7.4	393	596
XT2109 16	0.044 400	0.002 400	0.001 421	0.000 076	0.282 903	0.000 022	14.7	4.5	500	782
XT2109 17	0.066 500	0.001 400	0.002 437	0.000 045	0.283 059	0.000 021	14.7	11.3	284	395
XT2109 18	0.021 700	0.000 270	0.000 831	0.000 008	0.282 879	0.000 023	14.7	3.7	526	835
XT2113 01	0.039 540	0.000 580	0.001 534	0.000 020	0.283 101	0.000 020	14.5	12.9	216	294
XT2113 02	0.021 630	0.000 290	0.000 750	0.000 008	0.282 764	0.000 020	14.5	-0.4	687	1096
XT2113 03	0.052 080	0.000 200	0.001 742	0.000 009	0.282 886	0.000 022	14.5	3.9	529	821
XT2113 04	0.059 000	0.000 660	0.002 005	0.000 019	0.282 930	0.000 019	14.5	5.4	469	721
XT2113 05	0.057 330	0.000 510	0.002 039	0.000 022	0.282 924	0.000 022	14.5	5.2	478	735
XT2113 06	0.067 280	0.000 580	0.002 440	0.000 025	0.282 957	0.000 026	14.5	6.4	435	660
XT2113 07	0.061 650	0.000 550	0.002 091	0.000 012	0.282 921	0.000 022	14.5	5.1	483	741
XT2113 08	0.040 210	0.000 100	0.001 389	0.000 005	0.282 921	0.000 021	14.5	5.1	474	741
XT2113 09	0.044 200	0.001 100	0.001 571	0.000 047	0.282 991	0.000 025	14.5	7.6	375	583
XT2113 10	0.028 704	0.000 039	0.001 141	0.000 001	0.283 055	0.000 019	14.5	13.3	280	342
XT2113 11	0.037 800	0.001 100	0.001 569	0.000 045	0.283 047	0.000 018	14.5	13.1	294	359
XT2113 12	0.034 540	0.000 390	0.001 423	0.000 014	0.283 054	0.000 022	14.5	13.3	283	344
XT2113 13	0.035 900	0.000 790	0.001 471	0.000 034	0.283 042	0.000 024	14.5	13.0	301	368
XT2113 14	0.021 480	0.000 360	0.000 910	0.000 013	0.283 059	0.000 024	14.5	13.4	272	333
XT2113 15	0.048 140	0.000 800	0.001 993	0.000 021	0.283 062	0.000 022	14.5	13.6	276	327
XT2113 16	0.029 160	0.000 380	0.001 203	0.000 013	0.283 064	0.000 025	14.5	13.7	267	318
测点号	¹⁷⁶Yb/¹⁷⁷Hf	2σ	¹⁷⁶Lu/¹⁷⁷Hf	2σ	¹⁷⁶Hf/¹⁷⁷Hf	2σ	Age/Ma	ε_Hf(t)	T_DM/Ma	$T D M C$ /Ma
XT2113 17	0.030 010	0.000 410	0.001 204	0.000 018	0.283 064	0.000 019	14.5	13.8	267	317
XT2113 18	0.028 320	0.000 170	0.001 197	0.000 007	0.283 038	0.000 019	14.5	12.8	304	379
XT2113 19	0.029 950	0.000 840	0.001 200	0.000 033	0.283 062	0.000 023	14.5	13.5	270	327
XT2113 20	0.015 976	0.000 062	0.000 687	0.000 003	0.283 039	0.000 025	14.5	13.1	299	366
XT2113 21	0.027 390	0.000 360	0.001 144	0.000 014	0.283 056	0.000 022	14.5	13.5	278	336
XT2113 22	0.049 290	0.000 360	0.001 810	0.000 011	0.282 939	0.000 021	14.5	5.8	453	700
XT2113 23	0.052 340	0.000 200	0.001 751	0.000 004	0.282 924	0.000 019	14.5	5.2	474	734
XT2113 24	0.061 190	0.000 240	0.002 158	0.000 015	0.282 948	0.000 021	14.5	6.1	444	680
XT2116 01	0.054 280	0.000 470	0.002 087	0.000 013	0.282 953	0.000 024	15.2	6.3	436	668
XT2116 02	0.039 700	0.001 000	0.001 486	0.000 041	0.282 952	0.000 030	15.2	6.3	431	670
XT2116 03	0.016 500	0.001 000	0.000 636	0.000 036	0.282 854	0.000 029	15.2	2.8	559	893
XT2116 04	0.028 870	0.000 860	0.001 115	0.000 034	0.282 924	0.000 022	15.2	5.2	466	735
XT2116 05	0.010 560	0.000 310	0.000 407	0.000 010	0.282 893	0.000 019	15.2	4.2	501	801
XT2116 06	0.027 650	0.000 250	0.001 034	0.000 013	0.282 905	0.000 023	15.2	4.6	492	777
XT2116 07	0.027 590	0.000 320	0.001 138	0.000 009	0.283 021	0.000 049	15.2	8.6	328	515
XT2116 08	0.008 250	0.000 110	0.000 338	0.000 003	0.282 875	0.000 020	15.2	3.4	525	847
XT2116 09	0.039 460	0.000 460	0.001 554	0.000 017	0.282 879	0.000 021	15.2	3.7	537	835
XT2116 10	0.014 920	0.000 260	0.000 583	0.000 008	0.282 849	0.000 020	15.2	2.6	565	904
XT2116 11	0.031 100	0.000 630	0.001 151	0.000 021	0.282 918	0.000 027	15.2	5.0	475	748
XT2116 12	0.028 430	0.000 170	0.001 166	0.000 005	0.282 890	0.000 027	15.2	4.0	515	811
XT2116 13	0.031 120	0.000 560	0.001 195	0.000 013	0.282 890	0.000 026	15.2	4.0	516	812
XT2116 14	0.039 980	0.000 950	0.001 471	0.000 042	0.282 907	0.000 024	15.2	4.7	495	772
XT2116 15	0.016 610	0.000 250	0.000 678	0.000 007	0.282 880	0.000 026	15.2	3.8	523	831
XT2116 16	0.018 960	0.000 210	0.000 759	0.000 009	0.282 887	0.000 025	15.2	3.9	514	818
XT2116 17	0.017 200	0.000 130	0.000 674	0.000 004	0.282 894	0.000 021	15.2	4.0	503	807
XT2116 18	0.016 920	0.000 340	0.000 628	0.000 013	0.282 887	0.000 022	15.2	4.0	512	816

Fig.6 Zircon trace-element diagrams of Shigatse diorite porphyry dikes. a modified after [44]; b adapted from [45].

Fig.7 Zircon U-Pb concordia diagram and cathodoluminescence (CL) images

Fig.8 Adakitic discrimination diagrams of Shigatse diorite porphyry dikes. a modified after [54]; b adapted from [54].

Fig.9 Genetic discrimination diagrams of Shigatse diorite porphyry dikes. Base map adapted from [59] and the southern Tibet Miocene adakitic rocks data from [55,58].

Fig.10 Zircon U-Pb ages and Hf isotopes. The Gangdese Miocene adakitic rocks data adapted from [25,63-64].

Fig.11 Diagram of the genesis model of the Miocene adakite dike rock in Shigatse. Modified after [5].

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