Magnetic fabric study of the Keziletage pluton in east part of southern TianShan and its tectonic implications

Abstract

The Keziletage pluton which plays an important role in studying the nature of continental lithosphere and restraining the tectonic evolution of the Southern TianShan orogenic belts is located in the middle of the Keziletage synclinorium, a secondary tectonic unit of the South TianShan syncline fold belt. Emplacement mechanism of the Keziletage pluton in Xinjiang is studied through detailed analyses of magnetic fabrics. Data from 28 sampling sites within the pluton show that the value of the average susceptibility (Km) is high. The corrected anisotropy degree (Pj) is less than 1.2, which can be an indicator of flow magnetic fabrics. The shape parameter (T) of magnetic susceptibility ellipsoid displays that the Keziletage pluton is dominated by oblate compression fabric. Although the magnetic fabrics show NE-SW compression as a whole, the magnetic lineations are little over magnetic foliations. We suggest that the collision of Tarim blocks to YiLi-mid TianShan micro-plate became much weaker during the emplacement when the regional tectonic setting was changing to extension environment.