Fluid inclusion Ar-40/Ar-39 geochronology of andalusite from syntectonic quartz veins: New perspectives on dating deformation and metamorphism in low-pressure metamorphic belts

doi:10.1016/j.gca.2022.01.025

	Fluid inclusion Ar-40/Ar-39 geochronology of andalusite from syntectonic quartz veins: New perspectives on dating deformation and metamorphism in low-pressure metamorphic belts
	Xiao, Ming 8,9,10; Jiang, Yingde 9,10; Zhao, Guochun 7,8; Qiu, Huaning 5,6; Cai, Yue 3,4; Bai, Xiujuan 5,6; Yuan, Chao 9,10; Zhang, Wanfeng 9,10; Kong, Lingzhu 2,9,10; Wang, Sheng 1
刊名	GEOCHIMICA ET COSMOCHIMICA ACTA
	2022-04-15
卷号	323 页码:141-163
关键词	Andalusite Syn-tectonic quartz veins Ar-40/Ar-39 stepwise crushing Tectono-thermal evolution Metapelitic terranes
ISSN号	0016-7037
DOI	10.1016/j.gca.2022.01.025
通讯作者	Jiang, Yingde(jiangyd@gig.ac.cn)
英文摘要	Syn-tectonic quartz veins are widely present in low- to medium-grade metapelitic belts, however, dating these veins is challenging due to the lack of suitable target minerals for most geochronological methods. Andalusite is a common K-poor aluminosilicate mineral in these quartz veins. In this study, we demonstrate the feasibility of dating fluid inclusions in andalusite using the Ar-40/Ar-39 gentle stepwise crushing technique. Three andalusite samples in syn-tectonic quartz veins from the Chinese Altai, Central Asia yielded similar gas release patterns. The first crushing steps generated significant excess Ar-40 which likely originated from secondary gas inclusions. These steps gave anomalously old and quickly declining apparent ages. The following crushing steps generated less significant excess Ar-40 and yielded concordant and well-defined Early Permian ages of 282-277 Ma. These steps were likely dominated by the degassing of intra-crystal liquid-rich fluid inclusion planes. Two of the crushed powder samples from the stepwise crushing experiments were selected for additional Ar-40/Ar-39 stepwise heating using a furnace and yielded a much younger age of 216 Ma. Laser stepwise heating of muscovite flakes in two of the investigated andalusite samples and one chloridized biotite sample from a different andalusite-bearing quartz vein yielded Ar-40/Ar-39 ages of 243-241 Ma and 214 Ma, respectively. Compared with gases released from the crushing experiments, gases extracted from the heating experiments showed distinct Cl-K-Ca compositional characteristics and younger ages with near atmospheric initial Ar-40/Ar-36 value. These observations suggest that 1) contrary to common wisdom, excess Ar-40 in K-poor nesosilicates are preferably preserved in fluid inclusions rather than mineral lattices, and 2) K (Ar) contamination from K-bearing solid phases is negligible during gentle stepwise crushing. As such, the 282-277 Ma fluid inclusion Ar-40/Ar-39 ages could be considered as the timing of andalusite growth in the quartz veins. The younger muscovite Ar-40/Ar-39 ages likely record more recent cooling events. The youngest Ar-40/Ar-39 ages of the crushed andalusite powder and the biotite sample could reflect the timing of sericitization and chloritization of the samples, which is evidenced by petrologic observations and x-ray K mapping results. Furthermore, andalusite Ar-40/Ar-39 ages agree with the monazite/zircon U-Pb ages (280-273 Ma) of syn-tectonic leucogranite and pegmatite dykes and metamorphic ages (299-262 Ma) for the low-pressure metamorphic rocks of the region. These results suggest that fluid inclusion Ar-40/Ar-39 geochronology of andalusite can be used to constrain the timing of deformation and associated metamorphism in low-pressure metapelitic terranes, which can also provide more complete pictures of the tectono-thermal evolution in combination with traditional 40Ar/39Ar stepwise heating geochronology. (C) 2022 Elsevier Ltd. All rights reserved.
资助项目	Guangdong Basic and Applied Basic Research Foundation[2019A1515012190] ; National Natural Science Foundation of China[42022017] ; National Natural Science Foundation of China[41630315] ; National Natural Science Foundation of China[41688103] ; International Partnership Program of Chinese Academy of Sciences[132744KYSB20190039] ; China Postdoctoral Science Foundation[2019M663133] ; Director?s Fund of Guangzhou Insti-tute of Geochemistry, CAS[2019SZJJ-06] ; NSF[EAR-1714892] ; GIGCAS
WOS关键词	ASIAN OROGENIC BELT ; PALEOZOIC TECTONIC EVOLUTION ; NW CHINA IMPLICATIONS ; U-PB AGE ; EXCESS AR-40 ; CONTINENTAL-CRUST ; ALTAI OROGEN ; RETROGRADE METAMORPHISM ; ACCRETIONARY WEDGE ; NORTHWESTERN CHINA
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	PERGAMON-ELSEVIER SCIENCE LTD
WOS记录号	WOS:000831742200002
资助机构	Guangdong Basic and Applied Basic Research Foundation ; National Natural Science Foundation of China ; International Partnership Program of Chinese Academy of Sciences ; China Postdoctoral Science Foundation ; Director?s Fund of Guangzhou Insti-tute of Geochemistry, CAS ; NSF ; GIGCAS
内容类型	期刊论文
源URL	[http://ir.nigpas.ac.cn/handle/332004/41082]
专题	中国科学院南京地质古生物研究所
通讯作者	Jiang, Yingde
作者单位	1.Chinese Acad Sci, Ctr Excellence Life & Paleoenvironm, Hefei 230601, Peoples R China 2.Univ Chinese Acad Sci, Beijing, Peoples R China 3.Lamont Doherty Earth Observ Columbia Univ, 61 Rt 9W, Palisades, NY 10964 USA 4.Chinese Acad Sci, Nanjing Inst Geol & Palaeontol, State Key Lab Palaeobiol & Stratig, Nanjing 210008, Peoples R China 5.China Univ Geosci, Sch Earth Resources, Wuhan 430074, Peoples R China 6.China Univ Geosci Wuhan, Key Lab Tecton & Petr Resources, Minist Educ, Wuhan 430074, Peoples R China 7.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Northern Taibai St 229, Xi'an 710069, Peoples R China 8.Univ Hong Kong, Dept Earth Sci, Pokfulam Rd, Hong Kong, Peoples R China 9.CAS Ctr Excellence Deep Earth Sci, Guangzhou 510640, Peoples R China 10.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Peoples R China
推荐引用方式 GB/T 7714	Xiao, Ming,Jiang, Yingde,Zhao, Guochun,et al. Fluid inclusion Ar-40/Ar-39 geochronology of andalusite from syntectonic quartz veins: New perspectives on dating deformation and metamorphism in low-pressure metamorphic belts[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2022,323:141-163.
APA	Xiao, Ming.,Jiang, Yingde.,Zhao, Guochun.,Qiu, Huaning.,Cai, Yue.,...&Wang, Sheng.(2022).Fluid inclusion Ar-40/Ar-39 geochronology of andalusite from syntectonic quartz veins: New perspectives on dating deformation and metamorphism in low-pressure metamorphic belts.GEOCHIMICA ET COSMOCHIMICA ACTA,323,141-163.
MLA	Xiao, Ming,et al."Fluid inclusion Ar-40/Ar-39 geochronology of andalusite from syntectonic quartz veins: New perspectives on dating deformation and metamorphism in low-pressure metamorphic belts".GEOCHIMICA ET COSMOCHIMICA ACTA 323(2022):141-163.