Ductile deformation and regional strain field in the southern segment of the Tancheng-Lujiang fault zone,eastern China

Studies in a segment of the Tancheng-Lujiang fault zone show that it is a major transcurrent ductile shear zone with a considerable sinistral displacement. The formations (PtT₁₊₂) at depths of 5 to 15 km may have cropped out in this area during subsequent erosion. Many ductilely deformed structures are in it. The deformed zone was formed during the Indo-Sinian orogeny. On the basis of measurements and analyses of many deformed pebbles within the shear zone, it is suggested that the deformation in the zone studied may be catagorized as a variation of simple shear and plane strain with a constant volume. The intensely deformed belt is generally 40 to 50 km wide, with the average strain ratio 27.68 and the maximum greater than 87.37. From analysis of elongation strain, we estimate that the deformed belt has been elongated by 164.23 km and narrowed by 222.5 km. The internal belt was formed by a high shear strain , calculated to be more than 11.34. The deformed belt is associated with syntectonic dynamothermal metamorphism, represented by greenschist facies and retrogressive metamorphism on previous amphibolite facies.