Zircon U-Pb ages of Myaxunar jadeitite and constrain on the fluid in subduction zone of Neo-Tethys

	Zircon U-Pb ages of Myaxunar jadeitite and constrain on the fluid in subduction zone of Neo-Tethys
	Qi Min 3; Xiang Hua ; Zhang ZeMing ; Zhong ZengQiu 1
刊名	ACTA PETROLOGICA SINICA
	2014
卷号	30 期号:8 页码:2279-2286
关键词	Jadeitite Zircon U-Pb age Fluid-rock interactions Myanmar
ISSN号	1000-0569
英文摘要	The Jadeite rocks, which usually produced by the interaction between subduction-related fluids and ultramafic rocks (peridotite), are generally occurs in serpentinized ultramafic rocks in oceanic subduction zones. The Myanmar jadeitite is the largest and most important jadeitite deposits in the world, which occurs in a distinctive tectonic unit of the Tethys subduction zone. This paper presents a combined study of zircon geochronology, microstructure and trace elements in one Myanmar purple jadeitite. Most of the studied zircon grains occur as irregular crystals and experienced various degrees of recrystallization. Zircon U-Pb ages are positively correlated with Ti content indicating that the zircon with low Ti content are experienced higher degree of recrystallization. Unrecrystallized zircons are identified according CL images, they are characterized by relatively high Th/U ratios (0. 11 - 0. 29), relatively high REE concentrations (Sigma REE = 607 x 10(-6) similar to 2494 x 10(-6)) and Ti contents between 1. 58 x 10(-6) similar to 8. 60 x 10-(6). Crystallization temperature estimated by Ti-in-zircon geothermometer are 598 similar to 732 degrees C. The Pb-206/U-238 weighted mean age is 158 +/- 4Ma (MSWD =3. 5, N =6), which should represents the protolith age. Recrystallization zircons, which show discrepant patches zoning, can be divided into recrystallized zircon and incomplete recrystallized zircon according to their Th/U ratio and REE contents. Recrystallized zircons have relatively low Th/U ratios (0. 11 similar to 0. 17), relatively low REE concentrations (Sigma REE =143 similar to 362 x 10(-6)) and very low contents of Ti. Ti-in-zircon geothermometer gives the crystallization temperature of 473 -543 C, which is consistent with the jadeite formation temperature. The 206Pb/238U weighted mean age is 79 2Ma (MSWD = 0. 88, N = 5), which represents the formation age of the studied jadeitite. Incompletely recrystallized zircons give Th/U ratios of 0. 14 - 0. 43, Ce/Ce* ratios of 2. 83 44. 8 and Ti contents between O. 25 - 7. 17. The U-Pb ages range between 91 - 142Ma and we believed such ages has no clear geological implications. The results, together with previous studies suggest that multi stages of metasoamtism during the Neo-Tethys subduction and formed different generation of jadeitite between 147 - 79Ma.
学科主题	变质岩岩石学
WOS关键词	MYANMAR JADEITITE ; GEOCHRONOLOGY CONSTRAINTS ; NORTHWESTERN MYANMAR ; BURMA ; ROCKS ; TECTONICS ; EVOLUTION ; PETROLOGY ; ISOTOPE ; COMPLEX
WOS研究方向	Geology
语种	中文
出版者	SCIENCE PRESS
WOS记录号	WOS:000340023300012
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/40504]
专题	中国地质科学院地质研究所
作者单位	1.Chinese Acad Geol Sci, Inst Geol, State Key Lab Continental Tecton & Dynam, Beijing 100037, Peoples R China 2.China Univ Geosci, Fac Earth Sci, Wuhan 430074, Peoples R China 3.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Qi Min,Xiang Hua,Zhang ZeMing,et al. Zircon U-Pb ages of Myaxunar jadeitite and constrain on the fluid in subduction zone of Neo-Tethys[J]. ACTA PETROLOGICA SINICA,2014,30(8):2279-2286.
APA	Qi Min,Xiang Hua,Zhang ZeMing,&Zhong ZengQiu.(2014).Zircon U-Pb ages of Myaxunar jadeitite and constrain on the fluid in subduction zone of Neo-Tethys.ACTA PETROLOGICA SINICA,30(8),2279-2286.
MLA	Qi Min,et al."Zircon U-Pb ages of Myaxunar jadeitite and constrain on the fluid in subduction zone of Neo-Tethys".ACTA PETROLOGICA SINICA 30.8(2014):2279-2286.