关键词: 裂变径迹, 前展式, 后展式, 构造隆升, 青藏高原

Abstract: In order to analyze changes in of tectonic deformation and extension mode during the process of eastward compression of Qinghai-Tibet Plateau, the eastern edge of Qinghai-Tibet Plateau is selected as the study area, and apatite/zircon fission track studies were carried out. The results show that many differences between the Zoige Basin and the Longmenshan Block in the aspect of low-temperature geochronology and tectonic uplift: the cooling rates of several samples in the Zoige basin are relatively stable, ranging from 1.257 ℃ to 1.285 ℃ /Myr, while the cooling rates of several samples in the Longmenshan Block changes greatly, ranging from 1.243 ℃ to 2.875 ℃ /Myr; Zoige Basin has experienced two obvious tectonic thermal events since 100 Ma with the first in 100-80 Ma (cooling rate is 4.40±0.395 ℃ /Myr) and the second in 21-12 Ma (cooling rate is 2.89±0.597 ℃ /Myr). The eastern edge of Longmenshan Block has generally shown a gradual increase in the degree of tectonic uplift since 70 Ma, and the uplift has continued to increase since 8 Ma with the cooling rate of 5.75±0.238 ℃ /Myr; The tectonic deformation of Zoige Basin can be classified as forward expansion, while the Longmenshan Block has backward expansion (especially since 8 Ma). The process mentioned above is summarized a“s reflection and refraction of tectonic expansion”, the“ reflection tectonic stress”reached current location of Longriba fault in Pliocene (about 4.48 Ma), with the result of the Longriba fault zone with the features of both thrust and dextral strike slip.

Key words: fission track, piggyback propagation, overstep propagation, tec tonic uplift, Qinghai-Tibet Plateau