盐源盆地重力异常解释推断及成盐远景区预测

The interpretation and inference of gravity anomaly and the prediction of salt formation prospect in Yanyuan basin

盐源盆地是一个新生代沉积盆地,该区三叠系白山组、盐塘组地层蕴藏丰富的岩盐矿产。已知盐井沟岩盐体共施工普查井4个、生产井1个,其中普3孔钻遇岩盐体,有效控制深度1001 m(未揭穿盐体)。利用该区最新的1∶5万重力数据,结合岩盐矿的物性和异常特征,建立了岩盐矿产的地质—地球物理模型。对局部重力异常进行了推断解释,并采用2.5D模型拟合剖面计算,得到引起局部异常的地质体空间几何形态和物性参数。根据本次重力工作成果,结合地质认识,在研究区内共划分2个成盐远景区,对下一步在该区找盐意义重大。

Yanyuan basin is a Cenozoic sedimentary basin in southwest Sichuan basin,where Baishan Formation strata and Yantang Formation strata have rich rock salt.There are four drill holes and a producing well in the salt range of Yanjinggou area,and although the drilling depth of Pu-3 well is 1001 meters,it does not intersect the salt deposit.The latest 1∶50000 gravimetric data were employed and processed in this paper to build geological-geophysical model of rock-salt minerals by integrating the physical characteristics with gravity anomaly features of rock salt deposit,and a gravimetric profile was simulated by performing the 2.5 D forward modelling calculation to infer the geometric and physical parameters of the geological bodies that result in local anomalies.Based on the interpretation of gravity anomalies and the geological understanding of Yanyuan basin,the authors predicted two prospective zones for rock salt exploration in the study area,which has great prospecting significance in Yanyuan basin.