地震CT在寻找隐伏铜镍矿中的应用

SEISMIC TOMOGRAPHY AND ITS APPLICATION TO PROSPECTING OF CONCEALED NICKEL-COPPER ORE

用透射地震ＣＴ方法在金川龙首矿进行了隐伏铜镍矿体的探测试验．试验是在地下５００ｍ的１２８０平面上进行的，覆盖面积３００ｍ×３００ｍ．使用ＥＳ－２４０１Ｘ型４８道高分辨数字地震仪．铜镍矿体为高波速值的超基性侵入岩，采用纵波速度作为层析物理量是敏感的．研究区划分成８１×６４个单元，单元体大小为４ｍ×４ｍ．有效地震射线７６１９条，使用联合迭代重建法（ＳＩＲＴ）求解慢度走时方程．速度图像及地质解释表明测区中西部有一个高波速异常体，推断与含铜镍矿体或花岗体有关；此外还发现一条近东西向的低波速带，推断为断裂．

Seismic Tomography Technique is applied to prospecting test of concealed Nickel-Copper ore in Jinchuan Longshou Mine, Northwest China. The prospecting test covers an area of 300m×300m in the depth of 500m underground. The equipment used is ES-2401X 48-channel Seismography. The Frequency bandwidth is selected from 400Hz to 4000Hz. The software of seismic tomography is developed by Institute of Geology, Academia Sinica. The test area is divided into total 81×64elements, individual size 4m×4m. The seismic waves are excited by dynamic source of 50g. Total 165 effective shots are available, and 7619 seismic rays are calculated into velocity imaging. The velocity image shows there is a high velocity zone of 40m×40m, with value over 5.3km/s, in the west part of the test area,deduced as a Nickel-Copper ore bearing district, and a low velocity belt in width of 10m in the middle from east to west, infered as a fault. Drilling confirms thees interpertation true.