论文部分内容阅读
本文介绍瞬变电磁方法在冀东沉积变质型铁矿勘查中的应用。根据冀东地区成矿地质背景,以及BIF型铁矿的矿体形态、产状、赋存部位、规模大小及含矿岩层特征,建立了层状模型、透镜体模型与向形模型三种地质模型。将地质模型转化为可处理的地球物理模型,按实际地质情况改变模型参数,完成了瞬变电磁的时域二维正演计算。分析了三种模型在多种情况下(低阻覆盖层、不同倾角、不同深度、发射源特征和不同电阻率)的瞬变电磁响应特征。结果表明,低阻覆盖层对于瞬变电磁场的扩散有一定的屏蔽作用,因而减小探测深度;随着矿体倾角的逐渐增大,瞬变电磁响应强度逐渐减弱,水平板状矿体比垂直板状矿体的响应要更为明显;勘探效果随着地质体埋深的增加而逐渐减弱;发射磁矩的大小对于瞬变电磁场的强弱产生直接影响,在实际应用中需要结合多方面因素,选择最佳的发射边长来达到最佳的勘查效果。利用冀东司家营地区进行的瞬变电磁勘察数据,研究了该地区铁矿床的瞬变电磁响应特征,验证了上述模型的结论。
This paper introduces the application of transient electromagnetic method in the prospecting of sedimentary metamorphic iron ore in eastern Hebei. According to the mineralization geological background of Jidong area and the shape, occurrence, occurrence, size and ore-bearing strata of BIF iron ore, the authors established three kinds of geological models: layered model, lens model and directional model model. Transforming the geological model into a manageable geophysical model, changing the model parameters according to the actual geological conditions, and completing the two-dimensional forward modeling of the transient electromagnetic field in the time domain. The transient electromagnetic responses of the three models under different conditions (low resistance overburden, different dip angles, different depths, source characteristics and different resistivities) are analyzed. The results show that the low resistivity cover has a certain shielding effect on the transient electromagnetic field diffusion, thus reducing the detection depth. With the gradual increase of ore body inclination, the transient electromagnetic response strength gradually weakened, The response of the plate-shaped ore body is more obvious; the exploration effect decreases gradually with the increase of the buried depth of the geological body; the size of the transmitting magnetic moment has a direct impact on the strength of the transient electromagnetic field. In practical application, , Choose the best launch side to achieve the best exploration results. Based on the transient electromagnetic survey data of Jidong Sijiaying area, the transient electromagnetic response characteristics of the iron deposits in the area are studied, and the conclusion of the above model is verified.