重力方法在库车坳陷钾盐远景调查评价中的应用效果分析

Application Effect Analysis of the Gravity Methods in the Prospecting Survey and Evaluation of Sylvite Located in Kuqa Depression

新疆库车坳陷的古盐湖沉积了巨厚的盐岩层,在构造环境上具备形成钾矿的条件。巨厚的盐岩层与围岩存在较明显的密度差异,这一差异可以在地表产生足够大的布格重力异常的变化,通过分析重力场的变化可以反过来定性的分析深部盐岩层厚度变化特征。通过分析厚度变化特征,再结合地质、钻探资料,可以圈定有利于聚盐成钾的次级凹陷。笔者采用相应的数据处理手段,提取出了反应目的层盐岩厚度变化的布格重力剩余异常。利用剩余异常反推的盐岩层厚度变化情况与已知钻孔所揭示的盐岩层厚度变化情况吻合度较高,达到利用重力方法找(钾)盐岩的效果。

The ancient saline lake of the Xinjiang Kuqa depression deposits huge thick salt rocks, which is suitable tectonic setting for the potash salt ore development. The obvious density varia- tion between the huge thick salt rocks and the wall rocks can form a large enough change of bou- guer gravity anomaly on the earth＇s surface. The thickness change characteristics of deep salt rocks can be analyzed qualitatively in reverse by studying the change of the gravitational field. The secondary depression favorable for potash ore concentration can be circled by analyzing the thickness change characteristics and the geological and drilling data. This paper picks up the bouger gravity residual anomaly which reflects the taking corresponding data processing means. The salt thickness change of the target stratum, by salt thickness change inferred by the residual a nomaly is fitted with that explored by drills, which achieves the purpose of looking for potash ore by gravity measures.