广西灵山断裂北段晚更新世以来地质地貌特征

Geological and Geomorphological Features of Northern Lingshan Fault in Guangxi Since Late Pleistocene

灵山断裂北段位于广西钦州市灵山县,其活动性较强,但关于断裂沿线晚更新世以来的地质地貌特征目前还没有系统的研究报道。为了查明灵山断裂北段晚更新世以来的地质地貌特征,采用地质地貌详细调查、槽探、微地貌测量、OSL测年等方法,获得约17ka以及全新世以来的位移速率。结果表明:灵山断裂北段自晚更新世以来运动性质为右旋走滑兼正断,断裂沿线地质地貌主要表现为断错冲沟水系、冲洪积扇体变形、断错河流阶地、陡坎等;灵山断裂北段晚更新世以来活动明显,约17ka以来水平位移速率为1.27~1.54mm/a,垂直位移速率为0.53~0.65mm/a;全新世仍有活动,约2 360a以来水平位移速率为1.21~1.63mm/a,垂直位移速率为0.53mm/a。

The northern Lingshan fault is located in Lingshan County, Qinzhou, Guangxi Province. The northern Lingshan fault is quite active, but its geological and geomorphological features have never been systematically studied. In this study geological and geomorphological survey, trenching and OSL dating methods are adopted to determine its geological and geomorphological features of the northern Lingshan fault since Late Pleistocene and its displacement rate for about 17 000 a. The results show that the kinetic property of northern Lingshan fault is dextral strike-slip fault with normal fault, and that the geological and geomorphological features along the fault are of great variety. For example, the water systerms and terraces are dextrally slipped, and the alluvial fan conglomerates are deformed. Its dextral slip rate is 1.27--1.54mm/a, vertical movement rate is 0.53--0. 65 mm/a since about 17 000 a. The fault was also active in Holocene, with its dextral slip rate at 1.21--1.63 mm/a, and vertical movement rate at 0.53 mm/a since about 2 360 a.