| Abstract: | Abstract The Pearl River Delta in SE China is commonly believed as originating from continuous subsidence of the basement fault-(bounded) blocks initiated at the about 60 ka B.P. A section recently exposed at Xilingang in the hinterland of the Pearl River Delta, however, reveals that the fault-block movement is likely periodic or paroxysmal. Quaternary system of the section can be divided into three parts named as layer A, B and C from the bottom upwards. Both layer A and B are alluvial while layer C is aeolian. OSL dating of sediments proves that layer A is older than 43 ka, layer B in between 43-23ka and layer C younger than 23ka. The unconformable contact with a dip angle larger than 30° between layer A and B suggests a paroxysmal tilting and subsidence of basement fault-blocks after the formation of layer A. The upper interface of layer B is about 20 meters high above the sea level while that in the delta plain used to be buried at 20 meters under the S.L., implying a relatively rapid uplifting of the Xilingang hill after formation of layer B. Three layers, i.e. layer A, B and C are all cut off by a NNE trending normal fault with a fault-throw of 53cm, suggesting that the third paroxysmal movement of fault-blocks in the Pearl River Delta were occurred in recent epoch. |
