A new attempt to map the northern segment of the Lvliang Mountains， Shanxi， using the slab method

Abstract：This paper introduces the main results obtained in mapping the ancient orogenic area in the northern segment of the Lüliang Mountains， Shanxi， with the slab method. By 1∶250 000 mapping， three important tectonic boundaries have been found， and on that basis three tectonic slabs have been defined. Each slab has a binary structure and three slabs overlap each other， suggesting strong crustal shortening， which proves the existence of the orogenic belt. The geological event that took place at 1850 Ma was convergence rather than breakup. The Lüliang orogeny resulted in real cratonization of the North China block. During the Lǚliang orogeny there occurred two types of ductile shear zones： I-type ductile shear zones occurred between slabs， and II-type ductile shear zones in the interior of a single slab. So it is necessary to distinguish them in geological maps.