Tracking partial melting and protolith nature by zircon U-Pb and Hf-O isotope compositions of migmatites in the North Dabie terrane with emphasis on Paleozoic low-delta O-18 magmatism

doi:10.1130/B31719.1

	Tracking partial melting and protolith nature by zircon U-Pb and Hf-O isotope compositions of migmatites in the North Dabie terrane with emphasis on Paleozoic low-delta O-18 magmatism
	Yang, Sai-Hong 1,4; Zhao, Yu-Jie 2; Liu, Xiao-Chi1 ; Li, Long 3; Wu, Yuan-Bao 2
刊名	GEOLOGICAL SOCIETY OF AMERICA BULLETIN
	2018
卷号	130 期号:1-2 页码:139-153
ISSN号	0016-7606
DOI	10.1130/B31719.1
文献子类	Article
英文摘要	An integrated study using cathodoluminescence (CL) images, U-Pb geochronology, and Hf-O isotopic compositions of zircons, and whole-rock geochemistry was carried out on migmatites from the North Dabie terrane in order to constrain the sources and processes of the melt during partial melting and implications for tectonics in the northern Yangtze block. CL imaging revealed that zircon grains in the migmatites occur as - either new crystals or overgrowth rims around older inherited cores. The zircons display euhedral in shape with oscillatory or weak zoning and variable Th/U ratios, suggesting that they are of metamorphic origin and grew during partial melting. These zircons have concordia U-Pb ages from 129 +/- 2 Ma to 140 +/- 4 Ma, indicating partial melting of the North Dabie terrane due to the extension and collapse of the thickened orogenic root in the Early Cretaceous. The metamorphic zircons in two leucosome samples show higher delta O-18 but lower epsilon(Hf)(t) values than the inherited zircons in the same sample or adjacent melanosome samples, suggesting that the leucosomes were derived from external melt. The large variation of zircon epsilon(Hf)(t) values (-17.9 +/- 0.5 to -4.6 +/- 0.6) in one leucosome sample implies mixing between outside Hf from external melt and internal Hf from the dissolution-reprecipitation of the inherited zircons. The metamorphic zircons in one melanosome sample have higher Hf-176/Hf-177 ratios than, but similar delta O-18 values to those of the inherited zircons in the same sample, providing strong evidence for the generation of the metamorphic zircons by breakdown of a zirconium-bearing phase other than zircon in a closed system. The inherited zircon cores show oscillatory or weak zoning, resorption textures, and overprinting by over-growth rims, suggesting that they are magmatic zircons inherited from the protoliths. Their U-Pb ages are ca. 450 Ma, providing unambiguous evidence for the presence of early Paleozoic magmatism in the DabieSulu orogen. The inherited zircon cores have epsilon(Hf)(t) values of 8.6-14.0 and depleted mantle model (T-DM2) ages of ca. 880-540 Ma, indicating prompt reworking of juvenile crust during their formation. Inherited zircons in two samples (a melanosome and a leucosome) show delta O-18 values of similar to 5.3 parts per thousand, suggesting no involvement of hydrothermal materials. In contrast, inherited zircons in a melanosome sample show delta O-18 values from 3.22 parts per thousand +/- 0.24 parts per thousand to 5.00 parts per thousand +/- 0.29 parts per thousand, with a weighted average of 4.28 parts per thousand +/- 0.23 parts per thousand. These values are distinctly lower than the normal mantle zircon values, suggesting the occurrence of Paleo-zoic low-delta O-18 magma in the northern part of the Yangtze block. The Paleozoic low-delta O-18 magma is inferred to have been generated by remelting of preexisting O-18-depleted rocks in a rift setting. Combined with previous geological observation, we proposed a rift setting for the northern Yangtze block during the early Paleozoic, which might have resulted in the final opening of the Paleotethys Ocean along the Qinling-Tongbai-Hong'an orogenic belt.
WOS关键词	ULTRAHIGH-PRESSURE METAMORPHISM ; EAST-CENTRAL CHINA ; SULU OROGENIC BELT ; TRACE-ELEMENT ; LU-HF ; TECTONIC EVOLUTION ; QINLING TERRANE ; GEOLOGICAL IMPLICATIONS ; CONTINENTAL SUBDUCTION ; CRUSTAL ARCHITECTURE
WOS研究方向	Geology
语种	英语
出版者	GEOLOGICAL SOC AMER, INC
WOS记录号	WOS:000418364200007
资助机构	Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; 41273035 ; 41273035 ; 41273035 ; 41273035 ; 41573047) ; 41573047) ; 41573047) ; 41573047) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; 41273035 ; 41273035 ; 41273035 ; 41273035 ; 41573047) ; 41573047) ; 41573047) ; 41573047) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; 41273035 ; 41273035 ; 41273035 ; 41273035 ; 41573047) ; 41573047) ; 41573047) ; 41573047) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; Chinese 973 project(2015CB856106) ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; National Natural Science Foundation of China(41625008 ; 41273035 ; 41273035 ; 41273035 ; 41273035 ; 41573047) ; 41573047) ; 41573047) ; 41573047)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/82250]
专题	中国科学院地质与地球物理研究所
通讯作者	Wu, Yuan-Bao
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China 2.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Fac Earth Sci, Wuhan 430074, Hubei, Peoples R China 3.Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2R3, Canada 4.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式 GB/T 7714	Yang, Sai-Hong,Zhao, Yu-Jie,Liu, Xiao-Chi,et al. Tracking partial melting and protolith nature by zircon U-Pb and Hf-O isotope compositions of migmatites in the North Dabie terrane with emphasis on Paleozoic low-delta O-18 magmatism[J]. GEOLOGICAL SOCIETY OF AMERICA BULLETIN,2018,130(1-2):139-153.
APA	Yang, Sai-Hong,Zhao, Yu-Jie,Liu, Xiao-Chi,Li, Long,&Wu, Yuan-Bao.(2018).Tracking partial melting and protolith nature by zircon U-Pb and Hf-O isotope compositions of migmatites in the North Dabie terrane with emphasis on Paleozoic low-delta O-18 magmatism.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,130(1-2),139-153.
MLA	Yang, Sai-Hong,et al."Tracking partial melting and protolith nature by zircon U-Pb and Hf-O isotope compositions of migmatites in the North Dabie terrane with emphasis on Paleozoic low-delta O-18 magmatism".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 130.1-2(2018):139-153.