Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and ~(40)Ar/~(39)Ar Geochronology

CORC > 北京大学 > 地球与空间科学学院

	Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and ~(40)Ar/~(39)Ar Geochronology
	Lu Zeng ; Zhang Lifei
刊名	Acta Geologica Sinica
	2016
关键词	pelitic schist HP–UHP metamorphism P–T pseudosection ~(40)Ar/~(39)Ar geochronology,Chinese western Tianshan
英文摘要	Metapelite is one of the predominant rock types in the high-pressure–ultrahigh-pressure (HP–UHP) metamorphic belt of western Tianshan, NW China; however, the spatial and temporal variations of this belt during metamorphism are poorly understood. In this study, we present comparative petrological studies and ~(40)Ar/~(39)Ar geochronology of HP and UHP pelitic schist exposed along the Habutengsu valley. The schist mainly comprises quartz, white mica, garnet, albite and bluish amphibole. In the MnO–Na_2O–CaO–K_2O–FeO–MgO–Al_2O_3–SiO_2–H_2O (MnNCKFMASH) system, P–T pseudosections were constructed using THERMOCALC 333 for two representative pelitic schists. The results demonstrate that there was a break in the peak metamorphic pressures in the Habutengsu area. The northern schist has experienced UHP metamorphism, consistent with the presence of coesite in the same section, while the southern one formed at lower pressures that stabilized the quartz. This result supports the previous finding of a metamorphic gradient through the HP–UHP metamorphic belt of the Chinese western Tianshan by the authors. Additionally, phengite in the northern schist was modelled as having a Si content of 3.55–3.70 (a.p.f.u.) at the peak stage, a value much higher than that of oriented matrix phengite (Si content 3.32–3.38 a.p.f.u.). This indicates that the phengite flakes in the UHP schist were subjected to recrystallization during exhumation, which is consistent with the presence of phengite aggregates surrounding garnet porphyroblast. The ~(40)Ar/~(39)Ar age spectra of white mica (dominantly phengite) from the two schists exhibit similar plateau ages of ca. 315 Ma, which is interpreted as the timing of a tectonometamorphic event that occurred during the exhumation of the HP–UHP metamorphic belt of the Chinese western Tianshan.; supported by National Natural Science Foundation of China; 中文核心期刊要目总览(PKU); 中国科技核心期刊(ISTIC); 中国科学引文数据库(CSCD); 2; 628-640; 90
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/446560]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Lu Zeng,Zhang Lifei. Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and ~(40)Ar/~(39)Ar Geochronology[J]. Acta Geologica Sinica,2016.
APA	Lu Zeng,&Zhang Lifei.(2016).Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and ~(40)Ar/~(39)Ar Geochronology.Acta Geologica Sinica.
MLA	Lu Zeng,et al."Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and ~(40)Ar/~(39)Ar Geochronology".Acta Geologica Sinica (2016).