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

doi:10.1111/1755-6724.12695

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 40Ar/39Ar Geochronology
	L(U) Zeng ; ZHANG Lifei
刊名	地质学报（英文版）
	2016
关键词	pelitic schist HP-UHP metamorphism P-T pseudosection 40Ar/39Ar geochronology Chinese western Tianshan pelitic schist HP-UHP metamorphism P-T pseudosection 40Ar/39Ar geochronology Chinese western Tianshan P-T PATH CONSISTENT THERMODYNAMIC DATA COESITE-BEARING ECLOGITE HP-LT ROCKS NW-CHINA TECTONIC IMPLICATIONS METAMORPHIC ROCKS SOUTHWEST TIANSHAN CENTRAL-ASIA TIEN-SHAN
DOI	10.1111/1755-6724.12695
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 Ar-40/Ar-39 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-Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O (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 Ar-40/Ar-39 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.; This study is financially supported by National Natural Science Foundation of China; SCI(E); luzeng@pku.edu.cn; 2; 628-640; 90
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/446417]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	L,ZHANG Lifei. Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and 40Ar/39Ar Geochronology[J]. 地质学报（英文版）,2016.
APA	L,&ZHANG Lifei.(2016).Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and 40Ar/39Ar Geochronology.地质学报（英文版）.
MLA	L,et al."Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and 40Ar/39Ar Geochronology".地质学报（英文版） (2016).