Apatite fission track evidence for the Cenozoic uplift of the Lüliang Mountains and a discussion on the uplift mechanism

Abstract：From part of huge sedimentary basin in Mesozoic to the present NS-treading gigantic mountains composed of geological bodies of various geological ages, there exists the product of uplift of Lüliang Mountains of different stages. Detailed field investigation and thermal chronologic study were carried out at the mutation positions of geomorphology and strata in north, middle and south sections of the mountains. The relationship of “age-depth” in apatite fission track and different erosion thicknesses in different parts of the mountains suggests that isostatic uplift was not responsible for the uplift of the Lüliang Mountains. EW-trending uneven erosion controlled by the thrust fault and distribution of annealing zone witnessed the fact that bilateral thrusts of NS-treading fault constituted the main uplift mechanism. According to the apatite fission track age from different parts of the Lüliang Mountains, the uplift can be subdivided into five stages, i.e., (58±3) Ma, (40±3) Ma, (30±3) Ma, (23±3) Ma and (10±3) Ma. The initial uplift originated from (58±3) Ma, then Ningwu fault began to form and resulted in the differential uplift pattern in the eastern part of North Lüliang Mountains. The differential erosion between Jinxi fault-fold belt and Lüliang Mountains block formed in different stages, the north was formed not later than (30±3) Ma, the middle was formed at (23±3) Ma, and the south was strengthened at (10±3) Ma.