The Late Pleistocene tectonic activities of Hainan Island appear various vertical movements and results in a series of river terraces developed in the island.The evolution of these terraces can reveal the characteristics of differential structural activities in different areas of Hainan Island.The optically stimulated luminescence(OSL)dating is used to date the river terraces of 6 rivers in the western Hainan Island.Based on a detailed field geological survey and geomorphology researches,the chronological framework of river terraces(27.3-29.6 ka,2.82-3.92 ka,0.60-0.93 ka,～0.40-0.50 ka)are set up.Combined with the tectonic activity and regional climate evolution around Hainan Island,the origin of those river terraces is discussed.The results show that T4 would be mainly caused by the climate changes.Climate changes altered runoff carrying capacity and sediment flux,leading to accumulation and erosion of these rivers.T3,T2 and T1 terraces would be controlled by multiple faults and the key factor for the development of terraces would be the intermittent differential tectonic uplift movement.The difference of river incision rate indicates that the rate of tectonic uplift rate in its mid-western area is higher than those of southwester area during 0.60-3.92 ka.
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万方数据
