EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Fluid inclusion 40Ar/39Ar geochronology of andalusite from syn-tectonic quartz veins: perspectives on dating regional deformation and metamorphism events

Ming Xiao1,2,3, Ying-De Jiang1,2, Hua-Ning Qiu4, and Guo-Chun Zhao3,5
Ming Xiao et al.
  • 1State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
  • 2CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
  • 3Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
  • 4Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education, Wuhan 430074, China
  • 5State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Northern Taibai Street 229, Xi’an 710069, China

A long-lasting orogenic process often generates vast complexity of deformation and metamorphism. Understanding the time scales of these processes is essential for the reconstruction of the finite architecture of a fossil orogenic belt, which, nevertheless, is not always straightforward. This is because multiple episodes of tectonic events would lead to multiple growth periods of accessory minerals and deformation of rock-forming minerals, which brings challenges for conventional dating methods such as U–Pb, K/Ar, and 40Ar/39Ar step-heating. Fortunately, the emplacement of syn-tectonic quartz veins witness the deformation process and potentially, the associated metamorphism. They, therefore, have the potential to provide vital age information for regional crustal evolution. These veins, especially those in metapelitic terranes, usually contain andalusite, a fluid inclusion bearing K-poor pure aluminosilicate, which stands a good chance for directly dating syn-tectonic veining events by the fluid inclusion 40Ar/39Ar stepwise crushing technique.

Combined with detailed petro-structural investigation, this study applies the fluid inclusion 40Ar/39Ar geochronology, for the first time, on andalusite minerals in syn-tectonic quartz veins from the Chinese Altai Orogenic Belt, Central Asia, to explore a new way for dating deformation and metamorphism. 40Ar/39Ar stepwise crushing on three andalusite samples yielded well-defined Early Permain ages of 282–274 Ma. These ages are consistent with previously published emplacement ages of regional syn-tectonic leucosome/pegmatite/granite veins and metamorphic ages for local and region schist/gneiss from the same metamorphic series. These results collectively suggest that the fluid inclusion 40Ar/39Ar geochronology of andalusite in syn-tectonic quartz veins has the potential to constrain the timing of fluid-present deformation and potentially contemporaneous metamorphism. This work, therefore, provides a novel way for the age constraints of regional tectonic-thermal evolution of metapelitic terranes in general.


This project was supported by the Guangdong Basic and Applied Basic Research Foundation (No. 2019A1515012190), the International Partnership Program of Chinese Academy of Sciences (No. 132744KYSB20190039) and the Projects funded by China Postdoctoral Science Foundation (No. 2019M663133). A Guangdong Special Support Program to Y.D. Jiang is also acknowledged.

How to cite: Xiao, M., Jiang, Y.-D., Qiu, H.-N., and Zhao, G.-C.: Fluid inclusion 40Ar/39Ar geochronology of andalusite from syn-tectonic quartz veins: perspectives on dating regional deformation and metamorphism events, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16501,, 2021.

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