Seminar

northern Tian Shan, China

The applications of the Optically Stimulated Luminescence (OSL) dating on the fluvial and tectonic processes in the northern Tian Shan, China

  • Date

    January 12,2021

  • Time

    10:00AM

  • Venue

    JL104

  • Speaker

    Mr. HU Guiming Department of Earth Sciences, HKU

The Tian Shan is a natural laboratory for the study of the interactions between the fluvial geomorphology and growth of thrust-related folds. The Simplifies procedures of OSL dating were developed to overcome the problems of dim and incomplete OSL signals of young sediments. It was applied on measuring the young quartz grains of the 18 river terraces in the Aijihai (AJH) gorge. The maximum vertical average river incision rate since ~3.7 ka is 7 cm/a. During the 3.0-2.4 ka, a rapid incision rate of 15 cm/a was found. In the lower AJH River, an excavated pit with a length of ~8 km was used to decipher the sedimentary aggradation since the late Quaternary. Based on the OSL dating on sand lenses in the pit, three apparent age hiatuses of depositions occurred at ~35-25 ka, ~15-11 ka and ~4.1-3.1 ka, respectively.

The Jiangnanmiao (JNM) backthrusting activities in the Qingshuihe (QSH) anticline were studied. The results show that the thrust and fold belt I is still active during the Holocene and the JNM backthrust is controlled by an active Holocene structural wedge. This structural deformation on the QSH anticline in fold Group I was dated from ~270 to ~3.5 ka, with slip rate ranging from ~0.4 mm/yr to ~0.8 mm/yr.