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2 2013

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ESR geochronology of the Minjiang River terraces at Wenchuan, eastern margin of Tibetan Plateau, China

Liu C.-R., Yin G.-M., Zhang H.-P., Zheng W.-J., Voinchet P., Han F., Wang D., Song W.-J., Bahain J.-J.

Geochronometria

2013

Vol. 40, no. 4

360--367

The Minjiang River terrace along the Longmen Shan fault zone near Wenchuan, at the eastern margin of the Tibetan Plateau, China, provides archives for tectonic activity and quaternary climate change. However, previous studies were not able to provide ages older than 100 ka due to the limitations of dating material or/and methods applied to date the fluvial sediments. In this study, we used the ESR signal of the Ti-Li center in quartz to obtain the ages of four higher terraces (T3-T6). According to the results, the terraces T3 to T6 were formed at 64±19 ka, 101±15 ka, 153±33 ka, and 423±115 ka, respectively. Combined with previous studies, these results indicate that the formations of all terraces correspond to glacial/interglacial transition periods, such as, T1-T5 being correlated to MIS2/1, MIS4/3, MIS5d/5c, and MIS6/5e respectively, while T6 probably to MIS12/11. According to these data, it is found that the average incision rate was significantly higher over the last 150 ka than that previous 100 ka (250 to 150 ka). As both tectonics and climate have affected the formation of these terraces, in addition to the overall uplifting of Tibetan Plateau, the regional uplift due to isostasy would be an additional tectonic factor in the formation of river terraces in the eastern margin of Ti-betan plateau.

ESR dating of the Donggutuo Palaeolithic site in the Nihewan Basin, northern China

Liu C.-R., Yin G.-M., Fang F., Voinchet P., Deng C.-L., Han F., Li J.-P., Song W.-J., Wang D., Bahain J.-J.

Geochronometria

2013

Vol. 40, no. 4

348--354

The fluvio-lacustrine sequences in the Nihewan Basin, northern China, provide important terrestrial archives about Palaeolithic settlements and, therefore, about early human occupation in high northern latitude in East Asia. Here we present detailed ESR dating of the Donggutuo Palaeo-lithic site, located in this basin. Four levels A, B, C and E of the Donggutuo archaeological layer yield ESR ages ranging from 1060±129 ka to 1171±132 ka with a mean of 1119±132 ka. The ages are con-sistent with the paleomagnetic data, which show that the Donggutuo Palaeolithic site lies just below the onset of the Jaramillo normal subchron (0.99-1.07 Ma). Furthermore, our results indicate that the reliable ESR dating range of bleached quartz using Ti-Li centre can be effectively extended to 1100 ka and the Ti-Li centre was zeroed before the last deposition, which requires improvement of the understanding of the bleaching mechanism conditions.