Genetic mineralogy of Late Cretaceous intermediate intrusive rocks in the eastern segment of the Gangdese Belt, southern Tibet—construction of a trans-crustal magma system

doi:10.13745/j.esf.sf.2022.2.83

Abstract

Abstract:

The trans-crustal magmatic system provides a new perspective for understanding the genesis of mineral and inter-mineral disequilibrium before consolidation. The rock-forming minerals may have experienced growth, erosion or fluid transformation in the magma chamber at different crustal levels. How to trace and sort out the evolutionary history of different rock-forming minerals has become a key scientific issue for understanding the genesis of magmatic rocks. We focus on the clinopyroxene-bearing quartz diorite and biotite diorite in the Lilong area on the southern margin of the Gangdese arc in Tibet to conduct a systematic morphological study of the main rock-forming minerals (clinopyroxene, amphibole, biotite, plagioclase, etc.), and to constrain the key elements of the trans-crustal magmatic system. According to the total REE (ΣREE) content of each mineral and the contact relationships between different minerals, clinopyroxene and amphibole in clinopyroxene-bearing quartz diorite are divided into type Ⅰ clinopyroxene (high ΣREE), type Ⅱ clinopyroxene (low ΣREE), type ⅠA amphibole (high ΣREE) and type ⅠB amphibole (low ΣREE). Amphibole in biotite diorite is classified as type Ⅱ amphibole. Thermobarometric and oxybarometric calculations yield the following results: type Ⅰ clinopyroxene: temperature 1159-1175 ℃, pressure 6.37-7.99 kbar, water content 2.5%-3.4%; type Ⅱ clinopyroxene: temperature 1180-1181 ℃, pressure 4.82-5.24 kbar, water content 2.4%-2.8%; Type ⅠA amphibole: temperature 806-854 ℃, pressure 3.20-4.34 kbar, water content 7.5%-7.9%; type ⅠB amphibole: temperature 776-848 ℃, pressure 1.96-3.86 kbar, water content 6.9%-8.6%; type Ⅱ amphibole: temperature 783-857 ℃, pressure 2.46-3.27 kbar, water content 6.5%-9.4%. The above results suggest that clinopyroxene and amphibole originate from different magmatic chambers, as the former has a higher temperature and pressure but lower water content than the latter. Based on the compositions of mineral melts at equilibria, it is inferred that clinopyroxene is derived from evolved basaltic-andesite magma, while amphibole melts, with lower Mg^# value, from rhyolitic magmas. In this study, the “antecrysts” of clinopyroxene and amphibole are identified, which suggest that the magmatic process was completed in an open magmatic system, and experienced different stages of magmatic recharge or mixing events. This study also finds that intermediate magmas can be produced via mixing of antecrysts of different sources with andesitic to rhyolitic melts.

Key words: antecrysts, clinopyroxene, amphibole, trans-crustal magmatic system, multiple magma chamber

CLC Number:

WANG Wenlu, LI Xiaowei, ZHANG Zeming, TIAN Zuolin, LI Zengsheng, SUN Yuqin, LIU Qiang, DING Huixia, HAO Zhaoge. Genetic mineralogy of Late Cretaceous intermediate intrusive rocks in the eastern segment of the Gangdese Belt, southern Tibet—construction of a trans-crustal magma system[J]. Earth Science Frontiers, 2023, 30(2): 183-214.

Figures/Tables 26

Fig.1 (a) Simplified geological map and tectonic units of the Tibetan Plateau and Gangdese and (b) geological map of the Langxian to Linzhi region. Modified after [41].

Table 1 Basic data for intermediate rock samples from eastern Gangdese, southern Tibet

样品号	岩性	采样位置	主要矿物组成	坐标
ML20-52	含单斜辉石石英闪长岩	里龙乡东侧	斜长石+单斜辉石+角闪石+黑云母+石英	29°08'01.088″N 93°54'22.434″E
LL20-17 LL20-18	含单斜辉石石英闪长岩	里龙乡	斜长石+单斜辉石+角闪石+黑云母+石英	29°07'06.120″N 93°52'12.523″E
LL20-12 LL20-13	黑云母闪长岩	义当村	斜长石+角闪石+黑云母+石英	29°05'42.800″N 93°52'20.612″E
LL20-14 LL20-15	黑云母闪长岩	义当村	斜长石+角闪石+黑云母+石英	29°05'45.476″N 93°52'20.000″E

Fig.2 Photomicrographs and BSE images of Lilong intermediate rocks (a) Coronitic textures in amphibole surrounding clinopyroxene in clinopyroxene-bearing quartz diorite. (b) Coronitic textures in amphibole. (c) BSE image of Fig.2b. (d) Poikilitic textures in clinopyroxene and amphibole in clinopyroxene-bearing quartz diorite. (e) BSE image showing coronitic textures in clinopyroxene and amphibole and spongy structure of amphibole. (f) Sieve structure of amphibole in clinopyroxene-bearing quartz diorite. (g) Plagioclase and quartz in the spongy structure shown in Fig.2e. (h) Clinopyroxene in clinopyroxene-bearing quartz diorite with no contact with amphibole. (i) Poikilitic textures in clinopyroxene and broken amphibole. (j) Amphibole and plagioclase in biotite diorite. (k) Poikilitic textures in amphibole and biotite in biotite diorite. (l) Spongy structure of amphibole and titanite in biotite diorite. Pl: plagioclase; Amp: amphibole; Bt: biotite; Cpx: clinopyroxene; Q: quartz; Ttn: titanite. Mineral abbreviations after [46].

Table 2 Major element and trace element data of the Lilong intermediate rock

Fig.3 (a) K2O vs. SiO2 diagram (modified from [49]) and (b) A/CNK vs. A/NK diagram (modified from [50]) for Lilong intermediate rocks

Fig.4 Whole rock chondrite-normalized REE patterns (a) and primitive mantle-normalized trace element patterns (b) for Lilong intermediate rocks. Normalized values from [51].

Table 3 Major element composition of clinopyroxenes by electron probe microanalysis

探针点号		类型	w_B/%
探针点号		类型	SiO₂	TiO₂			Al₂O₃			FeO		MnO			MgO			CaO	Na₂O		K₂O			NiO			BaO		Cr₂O₃			Total
ML20-52	1.2	Ⅰ型单斜辉石	52.4	0.16			1.99			10.7		0.62			12.6			21.6	0.62		0.01			0			0		0			100.7
ML20-52	1.4		52.1	0.12			2.12			10.9		0.68			12.9			20.7	0.48		0.02			0.05			0		0.03			100.1
ML20-52	1.6		52.6	0.18			1.68			11.3		0.66			13			20.9	0.49		0.01			0.02			0.03		0.01			100.8
ML20-52	1.7		52.6	0.14			1.76			10.8		0.6			12.7			21.2	0.46		0			0			0		0			100.3
ML20-52	2.2		52.1	0.15			1.6			10.9		0.62			13			20.7	0.55		0.03			0			0		0			99.7
ML20-52	2.3		52.4	0.13			1.62			10.1		0.65			12.8			21.4	0.54		0			0.07			0		0.01			99.7
ML20-52	3.1		52	0.13			2			9.91		0.63			12.5			22	0.42		0			0			0.01		0.01			99.6
ML20-52	3.6		52.5	0.12			1.66			10.8		0.64			12.8			21.4	0.39		0			0			0		0.03			100.3
ML20-52	4.1		52.6	0.1			1.74			11.7		0.8			13.1			20.6	0.45		0.02			0.04			0		0			101.1
ML20-52	4.2		52.4	0.11			2.12			11.3		0.78			12.9			21	0.45		0			0			0.01		0			101
LL20-17	1.4		54.6	0.11			1.31			8.28		0.76			13.5			21.5	0.41		0.01			0			0.02		0.05			100.5
LL20-17	1.7		52.1	0.13			1.31			8.86		0.69			13.8			22.3	0.51		0.02			0			0		0.03			99.8
LL20-17	4.2		52.4	0.09			1.05			8.41		0.75			13.8			22.5	0.44		0			0.07			0.02		0			99.5
LL20-17	4.1		52.3	0.08			0.97			8.51		0.82			13.8			22.4	0.49		0.01			0			0		0.03			99.4
LL20-18	1.2	Ⅱ型单斜辉石	51.6	0.13			1.79			10.6		0.91			13.2			20.9	0.44		0			0			0.02		0.01			99.6
LL20-18	1.4		51.9	0.16			1.74			10.5		1.03			13.3			21.1	0.43		0			0			0		0.04			100.3
LL20-18	1.5		51.9	0.11			1.77			9.48		0.96			13.4			21.7	0.48		0.01			0.04			0		0			99.8
探针点号		类型	以6个氧原子和4个阳离子为基准计算的阳离子数
探针点号		类型	Si		Al^Ⅳ			Al^Ⅵ			Ti			Fe³⁺			Fe²⁺			Mn		Mg			Ca			Na			K
ML20-52	1.2	Ⅰ型单斜辉石	1.96		0.04			0.05			0			0.05			0.28			0.02		0.7			0.87			0.04			0
ML20-52	1.4		1.96		0.04			0.05			0			0.03			0.31			0.02		0.72			0.83			0.03			0
ML20-52	1.6		1.96		0.04			0.04			0			0.04			0.32			0.02		0.72			0.84			0.04			0
ML20-52	1.7		1.97		0.03			0.05			0			0.01			0.33			0.02		0.71			0.85			0.03			0
ML20-52	2.2		1.97		0.03			0.04			0			0.04			0.3			0.02		0.73			0.84			0.04			0
ML20-52	2.3		1.97		0.03			0.04			0			0.02			0.29			0.02		0.72			0.86			0.04			0
ML20-52	3.1		1.96		0.04			0.05			0			0.02			0.29			0.02		0.7			0.89			0.03			0
ML20-52	3.6		1.97		0.03			0.04			0			0.02			0.32			0.02		0.72			0.86			0.03			0
ML20-52	4.1		1.96		0.04			0.04			0			0.04			0.32			0.03		0.73			0.82			0.03			0
ML20-52	4.2		1.95		0.05			0.05			0			0.04			0.31			0.02		0.72			0.84			0.03			0
LL20-17	1.4		2.01		0			0.06			0			0			0.26			0.02		0.74			0.85			0.03			0
LL20-17	1.7		1.96		0.04			0.01			0			0.09			0.19			0.02		0.77			0.9			0.04			0
LL20-17	4.2		1.97		0.03			0.02			0			0.06			0.2			0.02		0.78			0.91			0.03			0
LL20-17	4.1		1.97		0.03			0.01			0			0.07			0.19			0.03		0.77			0.9			0.04			0
LL20-18	1.2	Ⅱ型单斜辉石	1.95		0.05			0.03			0			0.07			0.27			0.03		0.75			0.85			0.03			0
LL20-18	1.4		1.95		0.05			0.03			0			0.06			0.26			0.03		0.75			0.85			0.03			0
LL20-18	1.5		1.95		0.05			0.03			0			0.07			0.23			0.03		0.75			0.87			0.04			0
探针点号		类型	Wo			En			Fs				Mg^#			M $g 平衡熔体 #$				温度/℃			压力/MPa			深度/km				水含量_melt/%
ML20-52	1.2	Ⅰ型单斜辉石	44.1			35.7			18				71			40				1 175			714			26				3.2
ML20-52	1.4		42.7			36.9			18.6				70			39				1 173			799			28.7				2.8
ML20-52	1.6		42.5			36.7			18.9				70			39				1 170			699			25.6				2.8
ML20-52	1.7		43.7			36.4			18.2				69			38				1 164			737			26.8				3
ML20-52	2.2		42.5			37			18.4				71			40				1 172			721			26.3				2.8
ML20-52	2.3		44			36.7			17.3				71			40				1 166			711			25.9				3.2
ML20-52	3.1		45.4			36			17				71			40				1 159			655			24.2				3.4
ML20-52	3.6		43.8			36.5			18.3				69			38				1 166			637			23.6				3
ML20-52	4.1		41.9			36.9			19.7				69			38				1 174			702			25.7				2.6
ML20-52	4.2		42.8			36.5			19.1				70			39				1 172			754			27.3				2.9
LL20-17	1.4		44.7			39			14.8				74			44				1 167			665			24.5				2.5
LL20-17	1.7		44.8			38.5			14.9				80			53				1 174
LL20-17	4.2		45.3			38.8			14.3				79			51				1 171
LL20-17	4.1		45			38.6			14.6				80			52				1 172
LL20-18	1.2	Ⅱ型单斜辉石	42.7			37.5			18.2				74			44				1 181			524			20.1				2.6
LL20-18	1.4		42.7			37.5			18.2				74			44				1 181			482			18.7				2.4
LL20-18	1.5		44			37.7			16.5				77			47				1 180			495			19.1				2.8

Table 3 Major element composition of clinopyroxenes by electron probe microanalysis

探针点号		类型	w_B/%
探针点号		类型	SiO₂	TiO₂			Al₂O₃			FeO		MnO			MgO			CaO	Na₂O		K₂O			NiO			BaO		Cr₂O₃			Total
ML20-52	1.2	Ⅰ型单斜辉石	52.4	0.16			1.99			10.7		0.62			12.6			21.6	0.62		0.01			0			0		0			100.7
ML20-52	1.4		52.1	0.12			2.12			10.9		0.68			12.9			20.7	0.48		0.02			0.05			0		0.03			100.1
ML20-52	1.6		52.6	0.18			1.68			11.3		0.66			13			20.9	0.49		0.01			0.02			0.03		0.01			100.8
ML20-52	1.7		52.6	0.14			1.76			10.8		0.6			12.7			21.2	0.46		0			0			0		0			100.3
ML20-52	2.2		52.1	0.15			1.6			10.9		0.62			13			20.7	0.55		0.03			0			0		0			99.7
ML20-52	2.3		52.4	0.13			1.62			10.1		0.65			12.8			21.4	0.54		0			0.07			0		0.01			99.7
ML20-52	3.1		52	0.13			2			9.91		0.63			12.5			22	0.42		0			0			0.01		0.01			99.6
ML20-52	3.6		52.5	0.12			1.66			10.8		0.64			12.8			21.4	0.39		0			0			0		0.03			100.3
ML20-52	4.1		52.6	0.1			1.74			11.7		0.8			13.1			20.6	0.45		0.02			0.04			0		0			101.1
ML20-52	4.2		52.4	0.11			2.12			11.3		0.78			12.9			21	0.45		0			0			0.01		0			101
LL20-17	1.4		54.6	0.11			1.31			8.28		0.76			13.5			21.5	0.41		0.01			0			0.02		0.05			100.5
LL20-17	1.7		52.1	0.13			1.31			8.86		0.69			13.8			22.3	0.51		0.02			0			0		0.03			99.8
LL20-17	4.2		52.4	0.09			1.05			8.41		0.75			13.8			22.5	0.44		0			0.07			0.02		0			99.5
LL20-17	4.1		52.3	0.08			0.97			8.51		0.82			13.8			22.4	0.49		0.01			0			0		0.03			99.4
LL20-18	1.2	Ⅱ型单斜辉石	51.6	0.13			1.79			10.6		0.91			13.2			20.9	0.44		0			0			0.02		0.01			99.6
LL20-18	1.4		51.9	0.16			1.74			10.5		1.03			13.3			21.1	0.43		0			0			0		0.04			100.3
LL20-18	1.5		51.9	0.11			1.77			9.48		0.96			13.4			21.7	0.48		0.01			0.04			0		0			99.8
探针点号		类型	以6个氧原子和4个阳离子为基准计算的阳离子数
探针点号		类型	Si		Al^Ⅳ			Al^Ⅵ			Ti			Fe³⁺			Fe²⁺			Mn		Mg			Ca			Na			K
ML20-52	1.2	Ⅰ型单斜辉石	1.96		0.04			0.05			0			0.05			0.28			0.02		0.7			0.87			0.04			0
ML20-52	1.4		1.96		0.04			0.05			0			0.03			0.31			0.02		0.72			0.83			0.03			0
ML20-52	1.6		1.96		0.04			0.04			0			0.04			0.32			0.02		0.72			0.84			0.04			0
ML20-52	1.7		1.97		0.03			0.05			0			0.01			0.33			0.02		0.71			0.85			0.03			0
ML20-52	2.2		1.97		0.03			0.04			0			0.04			0.3			0.02		0.73			0.84			0.04			0
ML20-52	2.3		1.97		0.03			0.04			0			0.02			0.29			0.02		0.72			0.86			0.04			0
ML20-52	3.1		1.96		0.04			0.05			0			0.02			0.29			0.02		0.7			0.89			0.03			0
ML20-52	3.6		1.97		0.03			0.04			0			0.02			0.32			0.02		0.72			0.86			0.03			0
ML20-52	4.1		1.96		0.04			0.04			0			0.04			0.32			0.03		0.73			0.82			0.03			0
ML20-52	4.2		1.95		0.05			0.05			0			0.04			0.31			0.02		0.72			0.84			0.03			0
LL20-17	1.4		2.01		0			0.06			0			0			0.26			0.02		0.74			0.85			0.03			0
LL20-17	1.7		1.96		0.04			0.01			0			0.09			0.19			0.02		0.77			0.9			0.04			0
LL20-17	4.2		1.97		0.03			0.02			0			0.06			0.2			0.02		0.78			0.91			0.03			0
LL20-17	4.1		1.97		0.03			0.01			0			0.07			0.19			0.03		0.77			0.9			0.04			0
LL20-18	1.2	Ⅱ型单斜辉石	1.95		0.05			0.03			0			0.07			0.27			0.03		0.75			0.85			0.03			0
LL20-18	1.4		1.95		0.05			0.03			0			0.06			0.26			0.03		0.75			0.85			0.03			0
LL20-18	1.5		1.95		0.05			0.03			0			0.07			0.23			0.03		0.75			0.87			0.04			0
探针点号		类型	Wo			En			Fs				Mg^#			M $g 平衡熔体 #$				温度/℃			压力/MPa			深度/km				水含量_melt/%
ML20-52	1.2	Ⅰ型单斜辉石	44.1			35.7			18				71			40				1 175			714			26				3.2
ML20-52	1.4		42.7			36.9			18.6				70			39				1 173			799			28.7				2.8
ML20-52	1.6		42.5			36.7			18.9				70			39				1 170			699			25.6				2.8
ML20-52	1.7		43.7			36.4			18.2				69			38				1 164			737			26.8				3
ML20-52	2.2		42.5			37			18.4				71			40				1 172			721			26.3				2.8
ML20-52	2.3		44			36.7			17.3				71			40				1 166			711			25.9				3.2
ML20-52	3.1		45.4			36			17				71			40				1 159			655			24.2				3.4
ML20-52	3.6		43.8			36.5			18.3				69			38				1 166			637			23.6				3
ML20-52	4.1		41.9			36.9			19.7				69			38				1 174			702			25.7				2.6
ML20-52	4.2		42.8			36.5			19.1				70			39				1 172			754			27.3				2.9
LL20-17	1.4		44.7			39			14.8				74			44				1 167			665			24.5				2.5
LL20-17	1.7		44.8			38.5			14.9				80			53				1 174
LL20-17	4.2		45.3			38.8			14.3				79			51				1 171
LL20-17	4.1		45			38.6			14.6				80			52				1 172
LL20-18	1.2	Ⅱ型单斜辉石	42.7			37.5			18.2				74			44				1 181			524			20.1				2.6
LL20-18	1.4		42.7			37.5			18.2				74			44				1 181			482			18.7				2.4
LL20-18	1.5		44			37.7			16.5				77			47				1 180			495			19.1				2.8

Table 4 LA- ICP-MS in- situ trace elements analysis data of clinopyroxenes

Table 5 Major element composition of amphibole by electron probe microanalysis

Table 6 LA- ICP-MS in-situ trace elements analysis data of amphibole

Table 7 Major element composition of plagoclase by electron probe microanalysis

Table 8 Major element composition by electron probe microanalysis and LA-ICP MS in-situ trace elements analysis data of biotite

Fig.5 Classification diagrams for Lilong intermediate rocks. (a) Pyroxenes (after [57]). (b) Calcic amphiboles (after [58]). (c) Plagioclases (after [59]). (d) Biotite (after [59]).

Fig.6 Chondrite-normalized REE distribution patterns (a, c, e) and primitive mantle-normalized trace element distribution patterns (b, d, f) for different types of clinopyroxenes and amphiboles from Lilong intermediate rocks. Normalized values from [51].

Fig.7 BSE images and quantitative major and trace element mapping by LA-ICP-MS of spongy amphibole wrapping around clinopyroxene in clinopyroxene-bearing diorite. In BSE image, red circle indicates clinopyroxene core with amphibole on the peripheral; orange line indicates profiling line AB. Color scheme for element maps is based on probability density of element to accentuate distribution characteristics.

Fig.8 Variations along AB line (position see Fig.7) of important elements in spongy amphibole wrapping around clinopyroxene

Fig.9 Temperature (a, after [56,62]) and pressure (b, after [56,62]) contrast diagrams, and plots of temperature vs. SiO2 contents in melt at equilibrium (c) and temperature vs. magmatic water content in melt (d) for amphibole

Table 9 Trace element composition of calculated equilibrated melts with clinopyroxene

Fig.10 Chondrite-normalized REE distribution patterns for clinopyroxenes (a) and amphibole (b, c) from Lilong intermediate rock melts at equilibrium. Normalized values from [51]; whole rock REE value for each element averaged over all samples.

Table 10 Major element composition of calculated equilibrated melts with amphibole

标号		类型	w_B/%							Mg^#
标号		类型	SiO₂	TiO₂	FeO	MgO	CaO	K₂O	Al₂O₃	Mg^#
ML20-52	1.3	ⅠA型角闪石	76.8	0.21	1.87	0.44	2.73	4.06	15.5	30
ML20-52	1.J1		78.2	0.17	2.07	0.57	3.26	3.27	15.4	33
ML20-52	1.J2		75.2	0.22	2.26	0.48	2.81	4.39	16.1	27
ML20-52	1.J5		77.3	0.21	1.83	0.46	3.17	3.56	15.4	31
LL20-17	4.4	ⅠB型角闪石	80.5	0.16	1.03	0.26	2.23	3.93	14.1	31
LL20-17	4.6		79.7	0.17	1.1	0.27	2.38	3.95	14.4	31
LL20-18	2.4		74.3	0.29	1.97	0.45	2.85	4.22	15.6	29
LL20-18	2.5		74.6	0.3	1.94	0.45	2.88	4.17	15.4	29
LL20-18	4.3		75.4	0.26	1.79	0.37	2.55	4.24	15.2	27
LL20-18	4.4		75.5	0.25	1.77	0.39	2.6	4.28	15.3	28
LL20-18	4.5		75.9	0.24	1.92	0.44	2.67	4.22	15.5	29
LL20-18	4.6		75.4	0.26	1.85	0.42	2.67	4.2	15.5	29
LL20-12	1.3	Ⅱ型角闪石	76.7	0.26	1.91	0.46	2.77	3.47	14.9	30
LL20-12	1.4		76.7	0.24	1.93	0.44	2.65	3.43	14.8	29
LL20-12	1.8		76.8	0.26	1.9	0.48	2.9	3.52	15	31
LL20-12	2.2		75.5	0.3	2.25	0.54	2.98	3.46	15.2	30
LL20-13	1.2		75.8	0.3	2.01	0.46	2.74	3.73	14.9	29
LL20-13	1.3		75.4	0.29	2.15	0.47	2.74	3.59	15.1	28
LL20-13	2.1		77.4	0.25	1.8	0.43	2.64	3.71	14.8	30
LL20-13	2.3		74.4	0.28	3.09	0.75	3.04	3.6	15.5	30
LL20-13	2.5		76.2	0.29	2.11	0.48	2.78	3.84	15.1	29
LL20-15	4.3		78.2	0.21	1.38	0.3	2.44	4.14	15	28
LL20-15	4.4		78.1	0.21	1.49	0.34	2.62	4.11	15.5	29

Table 11 Partition coefficient and trace element composition of calculated equilibrated melts with amphibole

Fig.11 Equilibrium tests between clinopyroxenes (a) and amphibole (b) and their host rocks of Lilong intermediate rocks. The dotted curves after reference [75] represent the range of equilibrium compositions between mineral and melt using an Fe-Mg distribution coefficient of 0.28±0.08 for clinopyroxene (after reference [53]) and 0.28±0.11 for amphibole (after reference [62]).

Fig.12 Cross-plots of major oxide contents vs. SiO2 content in amphibole melt at equilibrium in comparison with whole-rock data

Table 12 Main features of some rock-forming minerals in intermediate rocks from the Lilong area

岩性	矿物	Mg^#	M $g 平衡熔体 #$	An	Nb/Ta	Nb/Ta _平衡熔体	Sr/Y	Sr/Y_平衡熔体	∑REE含量/ 10^-6	深度/km
含单斜辉石石英闪长岩	Ⅰ型单斜辉石	69~80	38~53				0.18~0.48	0.59~1.55	76.1~185.2	23.6~28.7
含单斜辉石石英闪长岩	Ⅱ型单斜辉石	74~77	44~47				0.80~0.91	2.57~2.91	51.5~58.8	18.7~20.1
含单斜辉石石英闪长岩	ⅠA型角闪石	62~63	27~33		13.4~14.9	12.6~14.0	0.23~0.28	4.59~6.53	471.2~530.2	12.2~16.4
含单斜辉石石英闪长岩	ⅠB型角闪石	61~67	27~31		12.3~22.2	11.6~20.9	0.70~0.85	10.7~18.29	104.7~196.2	7.7~15.1
黑云母闪长岩	Ⅱ型角闪石	59~66	29~36		13.3~22.2	12.5~20.9	0.56~1.61	9.53~30.7	129.6~200	9.5~12.6
两种岩性都存在	斜长石			35~48
含单斜辉石石英闪长岩	黑云母				12.1~21.7	3.63~6.50				6.22~7.44
黑云母闪长岩	黑云母				9.40~12.0	2.83~3.59				6.76~7.24

Table 12 Main features of some rock-forming minerals in intermediate rocks from the Lilong area

岩性	矿物	Mg^#	M $g 平衡熔体 #$	An	Nb/Ta	Nb/Ta _平衡熔体	Sr/Y	Sr/Y_平衡熔体	∑REE含量/ 10^-6	深度/km
含单斜辉石石英闪长岩	Ⅰ型单斜辉石	69~80	38~53				0.18~0.48	0.59~1.55	76.1~185.2	23.6~28.7
含单斜辉石石英闪长岩	Ⅱ型单斜辉石	74~77	44~47				0.80~0.91	2.57~2.91	51.5~58.8	18.7~20.1
含单斜辉石石英闪长岩	ⅠA型角闪石	62~63	27~33		13.4~14.9	12.6~14.0	0.23~0.28	4.59~6.53	471.2~530.2	12.2~16.4
含单斜辉石石英闪长岩	ⅠB型角闪石	61~67	27~31		12.3~22.2	11.6~20.9	0.70~0.85	10.7~18.29	104.7~196.2	7.7~15.1
黑云母闪长岩	Ⅱ型角闪石	59~66	29~36		13.3~22.2	12.5~20.9	0.56~1.61	9.53~30.7	129.6~200	9.5~12.6
两种岩性都存在	斜长石			35~48
含单斜辉石石英闪长岩	黑云母				12.1~21.7	3.63~6.50				6.22~7.44
黑云母闪长岩	黑云母				9.40~12.0	2.83~3.59				6.76~7.24

Fig.13 AlIV vs. La (a) and Hf (b) diagrams for clinopyroxene. Modified after [92].

Fig.14 Schematic model of a trans-crustal magmatic system revealed by the Lilong intermediate intrusive rocks

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