39Ar-40Ar Geochronology and EBSD Analysis of Mylonite in Zanhuang Massif:Implications for Paleoproterozoic Tectono-Thermal Evolution of North China Craton
Lü Tao
Jiang Kang
Wang Junpeng
Jiao Yunzhe
Zhai Lei
Abstract：The Zanhuang massif is located in the southeast part of the Central Orogenic Belt of the North China Craton,with complex rock association and tectonic deformation from Archaean to Paleoproterozoic.It is important to study the Early Precambrian tectono-thermal evolution of the Central Orogenic Belt of the North China Craton.In this study,a large-scale rock structure mapping,petrography,biotite 39Ar-40Ar geochronology and quartz EBSD fabric analysis of a well-out cropping ductile shear zone in the Zanhuang massif were carried out to define the kinematic characteristics and formation age of the shear zone,and to further explore the Paleoproterozoic tectono-thermal evolution of the North China Craton.The main lithology of the ductile shear zone is granitic mylonite,mainly composed of quartz(30％-40％),biotite(5％-15％)and feldspar(35％-55％).In the study area,the rocks are strongly deformed and metamorphosed,and a series of normal faults,folds,lineaments,foliations,and rotated porphyroblasts are developed.The surface occurrence and the trail of rotating patches all indicate the NW-SE shear.A plateau age of 1 781-1 745 Ma for biotite in mylonite was obtained by argon age test,indicating that the shear zone was formed in the Late Paleoproterozoic.EBSD fabric of quartz in mylonite shows that the quartz is mainly underside a-slip,indicating that the deformation temperature is lower than 400 ℃.Based on the previous research results,this study shows that the Zanhuang metamorphic complex experienced a strong disturbance caused by a tectono-thermal event in the Late Paleoproterozoic.
Keywords：Paleoproterozoicmylonite39Ar-40Ar datingtectono-thermal evolutionZanhuang massifNorth China Cratonstructural geology
Publication Date：2025-04-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 1273-1283 )