Chen Li-chun

Geological analysis and FT dating of the large-scale right-lateral strike-slip movement of the Red River fault zone

Tectonically, the large-scale right-lateral strike-slip movement along the Red River fault zone is characterized at its late phase with the southeastward extension and deformation of the Northwestern Yunnan normal fault depression on its northern segment, and the dextral shear displacement on its central-southern segment. Research of the relations between stratum deformation and fault movement on the typical fault segments, such as Jianchuan, southeast Midu, Yuanjiang River, Yuanyang, etc. since the Miocene Epoch shows that there are two times dextral faulting dominated by normal shearing occurring along the Red River fault zone since the Miocene Epoch. The fission track dating (abbreviated to FT dating, the same below) is conducted on apatite samples collected from the above fault segments and relating to these movements. Based on the measured single grain’s age and the confined track length, we choose the Laslet annealing model to retrieve the thermal history of the samples, and the results show that the fault zone experienced two times obvious shear displacement, one in 5.5 ± 1.5 MaBP and the other in 2.1 ± 0.8 MaBP. The central-southern segment sees two intensive uplifts of mountain mass in the Yuanjiang River-Yuanyang region at 3.6–3.8 MaBP and 1.6–2.3 MaBP, which correspond to the above-mentioned two dextral normal displacement events since the late Miocene Epoch.

Quantitative data about active tectonics and possible locations of strong earthquakes in the future in the northwestern Beijing

Deterministic, probabilistic and composite-grading methods are used to get the possible locations of strong earthquakes in the future in Norwest Beijing and its vicinity based on the quantitative data and their accuracy about active tectonics in the research area and by ordering, some questions in the results are also discussed. It shows that the most dangerous fault segments for strong earthquakes in the future include: segmentsB andA of the southern boundary fault of the Yangyuan basin, the southern boundary fault of the Xuanhua basin, the east segment of the southern Huai’an fault and the east segment of the northern Yanggao-Tianzhen fault. The most dangerous area is Yangyuan-Shenjing basin, the second one is Tianzhen-Huai’an-Xuanhua basin and the third dangerous areas are Wanquan-Zhangjiakou and northeast of Yuxian to southwest of Fanshan.

Measurement of terrace deformation and crustal shortening of some renascent fold zones within Kalpin nappe structure

The Kalpin nappe structure is a strongest thrust and fold deformation belt in front of the Tianshan Mountains since the Cenozoic time. The tectonic deformation occurred in 5–6 striking Mesozoic-Cenozoic fold zones, and some renascent folds formed on the recent alluvial-proluvial fans in front of the folded mountains. We used the total station to measure gully terraces along the longitudinal topographic profile in the renascent fold zones and collected samples from terrace deposits for age determination. Using the obtained formation time and shortening amount of the deformed terraces, we calculated the shortening rate of 4 renascent folds to be 0.1±0.03 mm/a, 0.12±0.04 mm/a, 0.59±0.18 mm/a, and 0.26±0.08 mm/a, respectively. The formation time of the renascent folds is some later than the major tectonic uplift event of the Qinghai-Tibet Plateau 0.14 Ma ago. It may be the long-distance effect of this tectonic event on the Tianshan piedmont fold belt.

Late Quaternary Large Earthquakes on the Western Branch of the Xiaojiang Fault and Their Tectonic Implications

Xiaojiang 差错是沿着西藏的高原的东南的边缘的一个主要活跃左侧面的差错。在云南省的最大的历史的地震，与大小 8 并且吝啬的 coseismic ∼ 的左侧面的排水量 6.9 m，发生在学习这个差错的 Xiaojiang 差错的西方的分支上在理解当前的变丑和西藏的高原的运动学的特征是重要的。活动和段很好在 Xiaojiang 差错上被承担了，当 paleoseismic 研究工作总是是这个差错上的弱连接时。为了调查 paleoseismic 历史和 Xiaojiang 的大地震活动，指责，我们在 Caohaizi 的北边打开了一条大沟下垂 Xiaojiang 差错的西方的分支上的池溏。六个 paleoseismic 事件通过 E6 被鉴别了，并且称为 E1 从对最年轻的炭和森林最旧是丰富的 20 件样品被标明日期在 40 000-36 抑制 paleoseismic 事件的年龄 300 BC ， 35 400-24 800 BC ， 9 500 BC广告 500 ，广告 390-720 ，广告 1120-1620 和广告1750礼品我们把最年轻的事件 E6 与 1833 M8 地震联系。事件 E4， E5 和 E6 在迟了的 Holocene 显示出 Xiaojiang 差错的西方的海滨的一个连续记录，与 370-480 年的平均复发间隔。在迟了的 Holocene 的大地震复发是远的不到 2000-4000 年的复发在以前的研究摆姿势。因此， Xiaojiang 差错上的地震危险应该被重新估计。而且， Xiaojiang 差错和其它上的大地震的不规则的复发在 Xianshuihe-Xiaojiang 系统指责，沿着西藏的高原的东南的边缘显示四川云南块的不平的向东南的挤出。