Petrogenesis and tectonic significance of OIB- and arc-type volcanic rocks in the western Yangtze Block: From intracontinental rifting to subduction

doi:10.13745/j.esf.sf.2020.12.4

Abstract

Abstract:

The late Mesoproterozoic to early Neoproterozoic magmatism in the western margin of the Yangtze Block played an important role in the geodynamics and crustal evolution of the Yangtze Block during the assembly and breakup of the Rodinia supercontinent. In this study, new SHRIMP zircon U-Pb dating yielded ages of (1035±15) and (884±9) Ma for the Tianbaoshan basaltic tuff and Yanbian hornblende andesite in the western Yangtze Block, respectively. The Tianbaoshan basaltic tuffs are of alkali basalt, exhibit OIB-like geochemical affinity and enrichments of LILE and HFSE, and have a positive ε_Nd(t) (4.6) value, with geochemical characteristics similar to ocean island balsalt. They are presumably derived from low-degree (1%-5%) partial melting of the upwelling asthenospheric mantle in an intra-plate rifting setting in the garnet+spinel stability field. The Yanbian hornblende andesites have calc-alkaline arc rocks signature, characterized by the enrichments of LILE and LREE and depletion of HFSE, significantly negative Nb, Ta and Ti anomalies, and positive ε_Nd(t) (1.1-2.8) values. They are derived from 5%-10% partial melting of mantle wedge in a subduction setting in the garnet+spinel stability field. On the basis of these results, we propose that the late Mesoproterozoic rifting-early Neoproterozoic subduction related volcanic rocks record a tectonic switch, from a continental-rifting basin to an convergent environment in the western Yangtze Block.

Key words: Meso-Neoproterozoic, western Yangtze Block, zircon U-Pb data, petrogenesis, tectonic setting

CLC Number:

ZHANG Jibiao, DING Xiaozhong, LIU Yanxue. Petrogenesis and tectonic significance of OIB- and arc-type volcanic rocks in the western Yangtze Block: From intracontinental rifting to subduction[J]. Earth Science Frontiers, 2021, 28(4): 250-266.

Figures/Tables 14

References 72

[1]	HOFFMAN P F. Did the breakout of Laurentia turn Gondwanaland inside-out?[J]. Science, 1991, 252(5011):1409-1412. DOI URL
[2]	KARLSTROM K E, ÅHÄLL K I, HARLAN S S, et al. Long-lived (1.8-1.0 Ga) convergent orogen in southern Laurentia, its extensions to Australia and Baltica, and implications for refining Rodinia[J]. Precambrian Research, 2001, 111(1/2/3/4):5-30.
[3]	BOGER S D, WILSON C J L, FANNING C M. Early Paleozoic tectonism within the East Antarctic Craton: the final suture between east and west Gondwana?[J]. Geology, 2001, 29(5):463-466. DOI URL
[4]	LI Z X, LI X H, ZHOU H W, et al. Grenvillian continental collision in South China: new SHRIMP U-Pb zircon results and implications for the configuration of Rodinia[J]. Geology, 2002, 30(2):163. DOI URL
[5]	JACOBS J, FANNING C M, BAUER W. Timing of Grenville-age vs. Pan-African medium- to high grade metamorphism in western Dronning Maud Land (East Antarctica) and significance for correlations in Rodinia and Gondwana[J]. Precambrian Research, 2003, 125(1/2):1-20. DOI URL
[6]	LI Z X, LI X H, KINNY P D, et al. The breakup of Rodinia: did it start with a mantle plume beneath South China?[J]. Earth and Planetary Science Letters, 1999, 173(3):171-181. DOI URL
[7]	LI Z X, LI X H, KINNY P D, et al. Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, South China and correlations with other continents: evidence for a mantle superplume that broke up Rodinia[J]. Precambrian Research, 2003, 122(1/2/3/4):85-109. DOI URL
[8]	GREENTREE M R, LI Z X, LI X H, et al. Late Mesoproterozoic to earliest Neoproterozoic basin record of the Sibao orogenesis in western South China and relationship to the assembly of Rodinia[J]. Precambrian Research, 2006, 151(1/2):79-100. DOI URL
[9]	ZHOU M F, MA Y X, YAN D P, et al. The Yanbian terrane (southern Sichuan Province, SW China): a Neoproterozoic arc assemblage in the western margin of the Yangtze block[J]. Precambrian Research, 2006, 144(1/2):19-38. DOI URL
[10]	ZHOU M F, YAN D P, WANG C L, et al. Subduction-related origin of the 750 Ma Xuelongbao adakitic complex (Sichuan Province, China): implications for the tectonic setting of the giant Neoproterozoic magmatic event in South China[J]. Earth and Planetary Science Letters, 2006, 248(1/2):286-300. DOI URL
[11]	LI X H, LI W X, LI Z X, et al. Amalgamation between the Yangtze and Cathaysia Blocks in South China: constraints from SHRIMP U-Pb zircon ages, geochemistry and Nd-Hf isotopes of the Shuangxiwu volcanic rocks[J]. Precambrian Research, 2009, 174(1/2):117-128. DOI URL
[12]	CHEN W T, SUN W H, ZHOU M F, et al. Ca. 1050 Ma intra-continental rift-related A-type felsic rocks in the southwestern Yangtze Block, South China[J]. Precambrian Research, 2018, 309:22-44.
[13]	CHEN W T, SUN W H, WANG W, et al. “Grenvillian” intra-plate mafic magmatism in the southwestern Yangtze Block, SW China[J]. Precambrian Research, 2014, 242:138-153.
[14]	ZHAO J H, ASIMOW P D, ZHOU M F, et al. An Andean-type arc system in Rodinia constrained by the Neoproterozoic Shimian ophiolite in South China[J]. Precambrian Research, 2017, 296:93-111.
[15]	ZHAO J H, LI Q W, LIU H, et al. Neoproterozoic magmatism in the western and northern margins of the Yangtze Block (South China) controlled by slab subduction and subduction-transform-edge-propagator[J]. Earth-Science Reviews, 2018, 187:1-18. DOI URL
[16]	ZHAO J H, ZHOU M F, WU Y B, et al. Coupled evolution of Neoproterozoic arc mafic magmatism and mantle wedge in the western margin of the South China Craton[J]. Contributions to Mineralogy and Petrology, 2019, 174(4):1-16.
[17]	LI Q W, ZHAO J H. The Neoproterozoic high-Mg dioritic dikes in South China formed by high pressures fractional crystallization of hydrous basaltic melts[J]. Precambrian Research, 2018, 309:198-211.
[18]	WANG D B, WANG B D, YIN F G, et al. Petrogenesis and tectonic implications of Late Mesoproterozoic A1- and A2-type felsic lavas from the Huili Group, southwestern Yangtze Block[J]. Geological Magazine, 2019, 156(8):1425-1439. DOI URL
[19]	ZHU Y, LAI S C, QIN J F, et al. Petrogenesis and geochemical diversity of late Mesoproterozoic S-type granites in the western Yangtze Block, South China: co-entrainment of peritectic selective phases and accessory minerals[J]. Lithos, 2020, 352/353:105326. DOI URL
[20]	ZHU Y, LAI S C, QIN J F, et al. Petrogenesis and geodynamic implications of Neoproterozoic gabbro-diorites, adakitic granites, and A-type granites in the southwestern margin of the Yangtze Block, South China[J]. Journal of Asian Earth Sciences, 2019, 183:103977.
[21]	ZHU Y, LAI S C, QIN J F, et al. Neoproterozoic peraluminous granites in the western margin of the Yangtze Block, South China: implications for the reworking of mature continental crust[J]. Precambrian Research, 2019, 333:105443. DOI URL
[22]	LI X H, LI Z X, ZHOU H W, et al. U-Pb zircon geochronology, geochemistry and Nd isotopic study of Neoproterozoic bimodal volcanic rocks in the Kangdian Rift of South China: implications for the initial rifting of Rodinia[J]. Precambrian Research, 2002, 113(1/2):135-154. DOI URL
[23]	LI X H, LI Z X, SINCLAIR J A, et al. Revisiting the “Yanbian Terrane”: implications for Neoproterozoic tectonic evolution of the western Yangtze Block, South China[J]. Precambrian Research, 2006, 151(1/2):14-30. DOI URL
[24]	ZHENG Y F, ZHANG S B, ZHAO Z F, et al. Contrasting zircon Hf and O isotopes in the two episodes of Neoproterozoic granitoids in South China: implications for growth and reworking of continental crust[J]. Lithos, 2007, 96(1/2):127-150. DOI URL
[25]	YANG Y J, ZHU W G, BAI Z J, et al. Petrogenesis and tectonic implications of the Neoproterozoic Datian mafic-ultramafic dykes in the Panzhihua area, western Yangtze Block, SW China[J]. International Journal of Earth Sciences, 2017, 106(1):185-213. DOI URL
[26]	SUN W H, ZHOU M F, GAO J F, et al. Detrital zircon U-Pb geochronological and Lu-Hf isotopic constraints on the Precambrian magmatic and crustal evolution of the western Yangtze Block, SW China[J]. Precambrian Research, 2009, 172(1/2):99-126. DOI URL
[27]	WANG W, ZHOU M F, ZHAO X F, et al. Late Paleoproterozoic to Mesoproterozoic rift successions in SW China: implication for the Yangtze Block - North Australia - Northwest Laurentia connection in the Columbia supercontinent[J]. Sedimentary Geology, 2014, 309:33-47. DOI URL
[28]	CHEN W T, ZHOU M F, ZHAO X F. Late Paleoproterozoic sedimentary and mafic rocks in the Hekou area, SW China: implication for the reconstruction of the Yangtze Block in Columbia[J]. Precambrian Research, 2013, 231:61-77. DOI URL
[29]	SUN W H, ZHOU M F. The ~860 Ma, Cordilleran-type Guandaoshan dioritic pluton in the Yangtze Block, SW China: implications for the origin of Neoproterozoic magmatism[J]. Journal of Geology, 2008, 116(3):238-253. DOI URL
[30]	张传恒, 高林志, 武振杰, 等. 滇中昆阳群凝灰岩锆石SHRIMP U-Pb年龄: 华南格林威尔期造山的证据[J]. 科学通报, 2007, 52(7):818-824.
[31]	尹福光, 孙志明, 任光明, 等. 上扬子陆块西南缘早—中元古代造山运动的地质记录[J]. 地质学报, 2012, 86(12):1917-1932.
[32]	ZHU W G, ZHONG H, LI Z X, et al. SIMS zircon U-Pb ages, geochemistry and Nd-Hf isotopes of ca. 1.0 Ga mafic dykes and volcanic rocks in the Huili area, SW China: origin and tectonic significance[J]. Precambrian Research, 2016, 273:67-89. DOI URL
[33]	耿元生, 旷红伟, 柳永清, 等. 扬子地块西、北缘中元古代地层的划分与对比[J]. 地质学报, 2017, 91(10):2151-2174.
[34]	LI X H, LI W X, LI Z X, et al. 850-790 Ma bimodal volcanic and intrusive rocks in northern Zhejiang, South China: a major episode of continental rift magmatism during the breakup of Rodinia[J]. Lithos, 2008, 102(1/2):341-357. DOI URL
[35]	ZHAO J H, ZHOU M F, YAN D P, et al. Reappraisal of the ages of Neoproterozoic strata in South China: no connection with the Grenvillian orogeny[J]. Geology, 2011, 39(4):299-302. DOI URL
[36]	PENG M, WU Y B, WANG J, et al. Paleoproterozoic mafic dyke from Kongling terrain in the Yangtze Craton and its implication[J]. Chinese Science Bulletin, 2009, 54(6):1098-1104.
[37]	ZHANG L J, MA C Q, WANG L X, et al. Discovery of Paleoproterozoic rapakivi granite on the northern margin of the Yangtze block and its geological significance[J]. Chinese Science Bulletin, 2011, 56(3):306-318. DOI URL
[38]	HAN Q S, PENG S B, POLAT A, et al. Petrogenesis and geochronology of Paleoproterozoic magmatic rocks in the Kongling complex: evidence for a collisional orogenic event in the Yangtze craton[J]. Lithos, 2019, 342/343:513-529. DOI URL
[39]	张宗清, 张国伟, 唐索寒, 等. 鱼洞子群变质岩年龄及秦岭造山带太古宙基底[J]. 地质学报, 2001, 75(2):198-204.
[40]	HUI B, DONG Y P, CHENG C, et al. Zircon U-Pb chronology, Hf isotope analysis and whole-rock geochemistry for the Neoarchean-Paleoproterozoic Yudongzi complex, northwestern margin of the Yangtze Craton, China[J]. Precambrian Research, 2017, 301:65-85. DOI URL
[41]	WANG K, LI Z X, DONG S W, et al. Early crustal evolution of the Yangtze Craton, South China: new constraints from zircon U-Pb-Hf isotopes and geochemistry of ca. 2.9-2.6 Ga granitic rocks in the Zhongxiang Complex[J]. Precambrian Research, 2018, 314:325-352. DOI URL
[42]	LU G M, WANG W, ERNST R E, et al. Petrogenesis of Paleo-Mesoproterozoic mafic rocks in the southwestern Yangtze Block of South China: implications for tectonic evolution and paleogeographic reconstruction[J]. Precambrian Research, 2019, 322:66-84.
[43]	GREENTREE M R, LI Z X. The oldest known rocks in south western China: SHRIMP U-Pb magmatic crystallisation age and detrital provenance analysis of the Paleoproterozoic Dahongshan Group[J]. Journal of Asian Earth Sciences, 2008, 33(5/6):289-302. DOI URL
[44]	四川省地质矿产局. 四川省区域地质志[M]. 北京: 地质出版社, 1991: 1-730.
[45]	ZHAO X F, ZHOU M F, LI J W, et al. Late paleoproterozoic to early mesoproterozoic Dongchuan group in Yunnan, SW China: implications for tectonic evolution of the Yangtze block[J]. Precambrian Research, 2010, 182(1/2):57-69. DOI URL
[46]	杨红, 刘福来, 刘平华, 等. 扬子地块西南缘大红山群石榴白云母-长石石英片岩的白云母⁴⁰Ar-³⁹Ar定年及其地质意义[J]. 岩石学报, 2013, 29(6):2161-2170.
[47]	ZHAO X F, ZHOU M F, HITZMAN M W, et al. Late Paleoproterozoic to early Mesoproterozoic Tangdan sedimentary rock-hosted strata-bound copper deposit, Yunnan Province, Southwest China[J]. Economic Geology, 2012, 107(2):357-375. DOI URL
[48]	关俊雷, 郑来林, 刘建辉, 等. 四川省会理县河口地区辉绿岩体的锆石SHRIMP U-Pb年龄及其地质意义[J]. 地质学报, 2011, 85(4):482-490.
[49]	耿元生, 杨崇辉, 王新社, 等. 扬子地台西缘变质基底演化[M]. 北京: 地质出版社, 2008: 1-50.
[50]	PECCERILLO A, TAYLOR S R. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, Northern Turkey[J]. Contributions to Mineralogy and Petrology, 1976, 58(1):63-81. DOI URL
[51]	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 Publication, 1989, 42(1):313-345. DOI URL
[52]	IRVINE T N, BARAGAR W R A. A guide to the chemical classification of the common volcanic rocks[J]. Canadian Journal of Earth Sciences, 1971, 8(5):523-548. DOI URL
[53]	ZHAO J H, ZHOU M F. Geochemistry of Neoproterozoic mafic intrusions in the Panzhihua district (Sichuan Province, SW China): implications for subduction-related metasomatism in the upper mantle[J]. Precambrian Research, 2007, 152(1/2):27-47. DOI URL
[54]	SHARMA M. Siberian traps[M]//MAHONEY J J, COFFIN M F. Large Igneous Provinces: continental, oceanic, and planetary flood volcanism, vol. 100. Washington DC: American Geophysical Union, 1997: 273-295.
[55]	NIU Y L, O’HARA M J. Origin of ocean island basalts: a new perspective from petrology, geochemistry, and mineral physics considerations[J]. Journal of Geophysical Research: Solid Earth, 2003, 108(B4):2209.
[56]	OLIEROOK H K H, JOURDAN F, MERLE R E, et al. Bunbury Basalt: Gondwana breakup products or earliest vestiges of the Kerguelen mantle plume?[J]. Earth and Planetary Science Letters, 2016, 440:20-32. DOI URL
[57]	CONDIE K C. Geochemical changes in basalts and andesites across the Archean-Proterozoic boundary: identification and significance[J]. Lithos, 1989, 23(1/2):1-18. DOI URL
[58]	KELEMEN P B, HANGHØJ K, GREENE A R. One view of the geochemistry of subduction-related magmatic arcs, with an emphasis on primitive andesite and lower crust[M]//Treatise on geochemistry. Amsterdam: Elsevier, 2007: 1-70.
[59]	赵振华. 微量元素地球化学原理[M]. 北京: 科学出版社, 2016.
[60]	MA L, WANG Q, WYMAN D A, et al. Late Cretaceous back-arc extension and arc system evolution in the Gangdese area, southern Tibet: geochronological, petrological, and Sr-Nd-Hf-O isotopic evidence from Dagze diabases[J]. Journal of Geophysical Research: Solid Earth, 2015, 120(9):6159-6181. DOI URL
[61]	BUSSY F, HERNANDEZ J, VON RAUMER J. Bimodal magmatism as a consequence of the post-collisional readjustment of the thickened Variscan continental lithosphere (Aiguilles Rouges-Mont Blanc Massifs, Western Alps)[J]. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 2000, 91(1/2):221-233.
[62]	FAN W M, GUO F, WANG Y J, et al. Post-orogenic bimodal volcanism along the Sulu orogenic belt in Eastern China[J]. Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, 2001, 26(9/10):733-746. DOI URL
[63]	PERFIT M R, GUST D A, BENCE A, et al. Chemical characteristics of island-arc basalts: implications for mantle sources[J]. Chemical Geology, 1980, 30(3):227-256. DOI URL
[64]	WANG X L, SHU L S, XING G F, et al. Post-orogenic extension in the eastern part of the Jiangnan orogen: evidence from ca 800-760 Ma volcanic rocks[J]. Precambrian Research, 2012, 222/223:404-423. DOI URL
[65]	MESCHEDE M. A method of discriminating between different types of mid-ocean ridge basalts and continental tholeiites with the Nb-1bZr-1bY diagram[J]. Chemical Geology, 1986, 56(3/4):207-218.
[66]	WOOD D A. The application of a Th-Hf-Ta diagram to problems of tectonomagmatic classification and to establishing the nature of crustal contamination of basaltic lavas of the British Tertiary Volcanic Province[J]. Earth and Planetary Science Letters, 1980, 50(1):11-30.
[67]	HAWKESWORTH C J, LIGHTFOOT P C, FEDORENKO V A, et al. Magma differentiation and mineralisation in the Siberian continental flood basalts[J]. Lithos, 1995, 34(1/2/3):61-88. DOI URL
[68]	MÜNKER C. The isotope and trace element budget of the Cambrian Devil River Arc System, New Zealand: identification of four source components[J]. Journal of Petrology, 2000, 41(6):759-788. DOI URL
[69]	SAUNDERS A D, NORRY M J, TARNEY J. Fluid influence on the trace element compositions of subduction zone magmas[J]. Philosophical Transactions of the Royal Society of London A, 1991, 335(1638):377-392.
[70]	WANG X C, LI X H, LI W X, et al. The Bikou basalts in the northwestern Yangtze Block, South China: remnants of 820-810 Ma continental flood basalts?[J]. Geological Society of America Bulletin, 2007, 120:1478-1492. DOI URL
[71]	邓尚贤. 滇中苍山群和苴林群的变质作用演化与地球化学研究[D]. 广州: 中国科学院广州地球化学研究所, 2000.
[72]	DU L L, GUO J H, NUTMAN A P, et al. Implications for Rodinia reconstructions for the initiation of Neoproterozoic subduction at ~860 Ma on the western margin of the Yangtze Block: evidence from the Guandaoshan Pluton[J]. Lithos, 2014, 196/197:67-82. DOI URL

Analysis	w_B/10^-6		Corrected ratio					Corrected age/Ma																Disc/%		Th/U ratios
Analysis	U	Th	²⁰⁷Pb/²⁰⁶Pb		1σ			²⁰⁷Pb/²³⁵U		1σ		²⁰⁶Pb/²³⁸U		1σ		²⁰⁷Pb/²⁰⁶Pb		1σ		²⁰⁶Pb/²³⁸U		1σ		Disc/%		Th/U ratios
HL-1
1.1	252	85		0.074 48		0.000 84	1.753		0.030		0.170 72		0.002 23		1 027		29		1 014		13		1		0.35
2.1	506	276		0.058 29		0.000 77	0.565		0.010		0.070 30		0.000 89		453		33		436.5		5.5		4		0.56
3.1	644	241		0.074 30		0.000 53	1.747		0.025		0.170 63		0.002 12		1 049		20		1 014		12		3		0.39
4.1	399	206		0.052 21		0.001 14	0.310		0.007		0.043 05		0.000 58		260		51		271.5		3.6		-4		0.53
5.1	202	151		0.096 42		0.001 23	3.606		0.067		0.271 22		0.003 64		1 530		26		1 546		20		-1		0.77
6.1	272	209		0.075 43		0.000 83	1.728		0.032		0.166 21		0.002 53		1 023		23		987		14		3		0.79
7.1	228	139		0.074 06		0.000 89	1.700		0.030		0.166 42		0.002 22		1 043		26		990		13		5		0.63
8.1	348	121		0.074 11		0.000 70	1.700		0.027		0.166 34		0.002 13		1 041		19		990		12		5		0.36
9.1	251	194		0.075 80		0.000 83	1.789		0.031		0.171 22		0.002 33		1 036		23		1 015		13		2		0.80
10.1	215	136		0.076 57		0.000 91	1.815		0.033		0.171 93		0.002 32		1 035		25		1 019		13		2		0.65
11.1	506	253		0.074 56		0.000 61	1.745		0.026		0.169 82		0.002 11		1 026		18		1 009		12		2		0.52
12.1	385	180		0.072 53		0.001 12	1.647		0.033		0.164 94		0.002 17		1 030		34		983		12		4		0.48
13.1	197	139		0.105 63		0.000 87	4.251		0.067		0.291 91		0.003 95		1 679		16		1 643		21		2		0.73
14.1	1 588	949		0.073 22		0.001 11	0.304		0.006		0.030 19		0.000 37		397		160		186.3		2.3		53		0.62
15.1	358	306		0.093 23		0.000 67	3.084		0.045		0.239 93		0.003 12		1 422		15		1 378		17		3		0.88
YB-1
1.1	139	118		0.071 52		2.0	1.398		3.2		0.141 91		2.5		785		62		849		20		-8		0.88
2.1	891	733		0.074 87		0.84	1.498		2.5		0.145 12		2.3		850		42		866		19		-2		0.85
3.1	199	163		0.070 41		1.8	1.508		3.0		0.155 24		2.4		941		50		930		21		1		0.85
4.1	206	155		0.064 92		1.8	1.302		3.0		0.145 53		2.4		760		61		876		20		-15		0.78
5.1	352	365		0.071 32		1.5	1.457		2.8		0.148 12		2.4		724		98		883		20		-22		1.07
6.1	404	293		0.067 33		4.6	1.330		5.2		0.143 43		2.3		852		160		865		19		-1		0.75
7.1	680	567		0.069 23		0.95	1.431		2.5		0.149 97		2.3		841		25		898		19		-7		0.86
8.1	354	242		0.070 33		1.3	1.507		2.7		0.155 41		2.3		877		29		929		20		-6		0.71
9.1	2 513	163		0.064 24		1.3	1.072		2.7		0.121 02		2.3		759		35		737		16		3		0.07
10.1	240	307		0.074 52		1.5	1.639		2.8		0.159 65		2.4		1 037		45		954		21		8		1.32
11.1	345	212		0.067 01		2.0	1.311		3.1		0.142 13		2.4		850		58		857		19		-1		0.64
12.1	388	314		0.067 12		2.1	1.368		3.1		0.147 82		2.3		777		49		886		19		-14		0.84
13.1	744	1 033		0.070 15		0.82	1.406		2.4		0.145 47		2.3		835		18		872		18		-4		1.44
14.1	131	92		0.065 83		2.6	1.329		3.5		0.146 62		2.4		777		57		881		20		-13		0.73
15.1	159	116		0.071 02		2.4	1.504		3.4		0.153 71		2.4		776		90		915		20		-18		0.75
16.1	180	213		0.069 71		1.6	1.483		2.8		0.154 23		2.4		853		34		922		20		-8		1.22
17.1	385	402		0.072 34		1.3	1.459		2.6		0.146 32		2.3		882		49		876		19		1		1.08
18.1	143	104		0.067 73		8.4	1.40		8.7		0.150 32		2.4		986		230		909		21		8		0.75
19.1	319	172		0.069 12		1.2	1.404		2.6		0.147 31		2.3		861		29		884		19		-3		0.56

Analysis	w_B/10^-6		Corrected ratio					Corrected age/Ma																Disc/%		Th/U ratios
Analysis	U	Th	²⁰⁷Pb/²⁰⁶Pb		1σ			²⁰⁷Pb/²³⁵U		1σ		²⁰⁶Pb/²³⁸U		1σ		²⁰⁷Pb/²⁰⁶Pb		1σ		²⁰⁶Pb/²³⁸U		1σ		Disc/%		Th/U ratios
HL-1
1.1	252	85		0.074 48		0.000 84	1.753		0.030		0.170 72		0.002 23		1 027		29		1 014		13		1		0.35
2.1	506	276		0.058 29		0.000 77	0.565		0.010		0.070 30		0.000 89		453		33		436.5		5.5		4		0.56
3.1	644	241		0.074 30		0.000 53	1.747		0.025		0.170 63		0.002 12		1 049		20		1 014		12		3		0.39
4.1	399	206		0.052 21		0.001 14	0.310		0.007		0.043 05		0.000 58		260		51		271.5		3.6		-4		0.53
5.1	202	151		0.096 42		0.001 23	3.606		0.067		0.271 22		0.003 64		1 530		26		1 546		20		-1		0.77
6.1	272	209		0.075 43		0.000 83	1.728		0.032		0.166 21		0.002 53		1 023		23		987		14		3		0.79
7.1	228	139		0.074 06		0.000 89	1.700		0.030		0.166 42		0.002 22		1 043		26		990		13		5		0.63
8.1	348	121		0.074 11		0.000 70	1.700		0.027		0.166 34		0.002 13		1 041		19		990		12		5		0.36
9.1	251	194		0.075 80		0.000 83	1.789		0.031		0.171 22		0.002 33		1 036		23		1 015		13		2		0.80
10.1	215	136		0.076 57		0.000 91	1.815		0.033		0.171 93		0.002 32		1 035		25		1 019		13		2		0.65
11.1	506	253		0.074 56		0.000 61	1.745		0.026		0.169 82		0.002 11		1 026		18		1 009		12		2		0.52
12.1	385	180		0.072 53		0.001 12	1.647		0.033		0.164 94		0.002 17		1 030		34		983		12		4		0.48
13.1	197	139		0.105 63		0.000 87	4.251		0.067		0.291 91		0.003 95		1 679		16		1 643		21		2		0.73
14.1	1 588	949		0.073 22		0.001 11	0.304		0.006		0.030 19		0.000 37		397		160		186.3		2.3		53		0.62
15.1	358	306		0.093 23		0.000 67	3.084		0.045		0.239 93		0.003 12		1 422		15		1 378		17		3		0.88
YB-1
1.1	139	118		0.071 52		2.0	1.398		3.2		0.141 91		2.5		785		62		849		20		-8		0.88
2.1	891	733		0.074 87		0.84	1.498		2.5		0.145 12		2.3		850		42		866		19		-2		0.85
3.1	199	163		0.070 41		1.8	1.508		3.0		0.155 24		2.4		941		50		930		21		1		0.85
4.1	206	155		0.064 92		1.8	1.302		3.0		0.145 53		2.4		760		61		876		20		-15		0.78
5.1	352	365		0.071 32		1.5	1.457		2.8		0.148 12		2.4		724		98		883		20		-22		1.07
6.1	404	293		0.067 33		4.6	1.330		5.2		0.143 43		2.3		852		160		865		19		-1		0.75
7.1	680	567		0.069 23		0.95	1.431		2.5		0.149 97		2.3		841		25		898		19		-7		0.86
8.1	354	242		0.070 33		1.3	1.507		2.7		0.155 41		2.3		877		29		929		20		-6		0.71
9.1	2 513	163		0.064 24		1.3	1.072		2.7		0.121 02		2.3		759		35		737		16		3		0.07
10.1	240	307		0.074 52		1.5	1.639		2.8		0.159 65		2.4		1 037		45		954		21		8		1.32
11.1	345	212		0.067 01		2.0	1.311		3.1		0.142 13		2.4		850		58		857		19		-1		0.64
12.1	388	314		0.067 12		2.1	1.368		3.1		0.147 82		2.3		777		49		886		19		-14		0.84
13.1	744	1 033		0.070 15		0.82	1.406		2.4		0.145 47		2.3		835		18		872		18		-4		1.44
14.1	131	92		0.065 83		2.6	1.329		3.5		0.146 62		2.4		777		57		881		20		-13		0.73
15.1	159	116		0.071 02		2.4	1.504		3.4		0.153 71		2.4		776		90		915		20		-18		0.75
16.1	180	213		0.069 71		1.6	1.483		2.8		0.154 23		2.4		853		34		922		20		-8		1.22
17.1	385	402		0.072 34		1.3	1.459		2.6		0.146 32		2.3		882		49		876		19		1		1.08
18.1	143	104		0.067 73		8.4	1.40		8.7		0.150 32		2.4		986		230		909		21		8		0.75
19.1	319	172		0.069 12		1.2	1.404		2.6		0.147 31		2.3		861		29		884		19		-3		0.56

Sample	Age/Ma	w_B/10^-6		¹⁴⁷Sm/¹⁴⁴Nd	¹⁴³Nd/¹⁴⁴Nd	(¹⁴³Nd/¹⁴⁴Nd)_i	1σ	ε_Nd(t)	T_DM1/Ma	T_DM2/Ma
Sample	Age/Ma	Sm	Nd	¹⁴⁷Sm/¹⁴⁴Nd	¹⁴³Nd/¹⁴⁴Nd	(¹⁴³Nd/¹⁴⁴Nd)_i	1σ	ε_Nd(t)	T_DM1/Ma	T_DM2/Ma
HL-2	1 035	10.3	50.4	0.123 49	0.511 537	0.511 302	0.000 002	4.6	1 309	1 294
YB-2	884	3.68	17.6	0.126 34	0.511 639	0.511 498	0.000 002	2.8	1 361	1 319
YB-3	884	3.83	16.5	0.140 26	0.511 591	0.511 498	0.000 003	1.8	1 548	1 394
YB-4	884	6.16	29.3	0.127 04	0.511 594	0.511 498	0.000 002	1.9	1 443	1 390
YB-5	884	4.79	23.0	0.125 84	0.511 554	0.511 498	0.000 002	1.1	1 503	1 453

Sample	Age/Ma	w_B/10^-6		¹⁴⁷Sm/¹⁴⁴Nd	¹⁴³Nd/¹⁴⁴Nd	(¹⁴³Nd/¹⁴⁴Nd)_i	1σ	ε_Nd(t)	T_DM1/Ma	T_DM2/Ma
Sample	Age/Ma	Sm	Nd	¹⁴⁷Sm/¹⁴⁴Nd	¹⁴³Nd/¹⁴⁴Nd	(¹⁴³Nd/¹⁴⁴Nd)_i	1σ	ε_Nd(t)	T_DM1/Ma	T_DM2/Ma
HL-2	1 035	10.3	50.4	0.123 49	0.511 537	0.511 302	0.000 002	4.6	1 309	1 294
YB-2	884	3.68	17.6	0.126 34	0.511 639	0.511 498	0.000 002	2.8	1 361	1 319
YB-3	884	3.83	16.5	0.140 26	0.511 591	0.511 498	0.000 003	1.8	1 548	1 394
YB-4	884	6.16	29.3	0.127 04	0.511 594	0.511 498	0.000 002	1.9	1 443	1 390
YB-5	884	4.79	23.0	0.125 84	0.511 554	0.511 498	0.000 002	1.1	1 503	1 453