成都平原西部土壤汞异常来源研究

四川唐昌地区是成都平原上典型的土壤汞含量高异常区。为研究汞异常来源，在该地区开展了多剖面地气测量，工作区面积约4 km2，布置了5条测量剖面，共121个测点，点距30 m。利用地气采样器积累式收集地气样品，采样时间为45 d，通过中子活化分析技术测试了地气样品中10余种元素。地气中As、Au、Fe、La、Sm等多个元素出现规律性异常分布，反映出该地区隐伏断裂的具体位置，断裂走向为NE 40°，宽度90～120 m。用ICP MS分析断裂上方收集的地气样品，发现含有微量的汞。成都平原西部汞异常区的分布趋势与隐伏断裂走向一致，且位置重合；而来自地下深部的汞能够随地气迁移至地表；隐伏断裂为地气迁移提供了有利通道，成为地表土壤汞异常的重要来源。成都平原西部汞异常是地球自身作用造成的.

ON THE SOURCE OF MERCURY ANOMALY IN SOIL OF WEST CHENGDU PLAIN

In Chengdu plain,Tangchang area is a representative area with high mercury anomaly in soil. In order to study the source of mercury anomaly, multi-section geogas prospecting was performed in Tangchang area. Five measuring lines with total 121 sampling points were laid in workplace of 4 km~2. The interval of sampling points was 30 m. A kind of special sampler was used to collect geogas,and the continuous sampling time is 45 d. More than 10 elements in geogas samples were determined by INAA. Several of them,including As,Au,Fe,La,Sm,exhibit a regular abnormal distribution,which reflects the concrete position of the concealed fault in this area. The fault strike is NE 40°,and the fault width is 90～120m. Determined by ICP-MS,trace mercury was found in geogas samples above the concealed fault. The regional distribution tendency of mercury anomaly area in west Chengdu plain is consistent with the concealed fault strike at the same position. The mercury can transfer along with the geogas from deep crust to surface soil. As a route way,the concealed fault provides a good condition for the transfer of geogas and mercury,which has become an important source of mercury anomaly in surface soil. The mercury anomaly in soil of west Chengdu plain is a result of earth self-action.