Abstract: The thickness of weathering rind on sandstone gravels from river terrace and alluvial fan deposits in Guangdong area increases with time. The growth curve of weathering thickness has been determined by using age control from radio carbon, thermolumi-nesecence and ESR techniques, showing the exponential decay of weathering rate. Weathering-rind thickness thus provives a measure of the age of deposits or geomorphic surfaces:T = 1485D^4.13 Where T=age in years, and D = weighted mean thickness in mm of about 50 gravels from the surficial part of deposit.Using this method, the authors have determined the ages of two types of geomorphic surfaces in Guangdong area. The ages of the first and second river terraces are determined as 1 000-13300 yrs, and 8600-26500 yrs., respectively; while those of the first-and second-order alluvial fans along the northern front of Zhaoqing basin as 51500 and 24400 yrs., respectively. Based on these data and geomorphic analysis of tectonic deformation, the rates of vertical faulting for three major NE-trending fault zones in the area can be estimated as 0.6-1.6mm/yr. for the period before mid-Holocene, and much less value for Latest Pleistocene.

Key words: Guangdong Province, Weathering rind on sandstone gravel, Growth curve of weathering-rind thickness, Late-Pleistocene age-dating, Geomorphic surface

摘要： 广东地区河流阶地和冲积扇沉积物中砂岩砾石风化晕随时间增厚。风化晕生长速度呈指数衰减,并拟合于下列公式:T 1485D^4.13这里T=时间,以年表示,D=沉积物表部约50块砾石风化晕厚度的加权平均值,以毫米表示。利用风化晕厚度确定出广东地区河流第一和第二级阶地分别为1000—13300年和8600—26500年,肇庆盆地北部山前地带第Ⅰ和第Ⅱ级冲积扇分别为51500年和24400年。同时,在构造地貌变形分析的基础上,估算出本区三条主要北东向断裂带在晚更新世—中全新世的垂直断层作用速度为0.6—1.6毫米/年,中全新世甚或晚更新世晚期以来的活动速度极小。

关键词: 广东, 风化晕, 晚更新世测年, 地貌面