Exploration for iron ore in Agbado-Okudu, Kogi State, Nigeria
Exploration for iron ore in Agbado-Okudu, Kogi State, Nigeria
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DOI：
10.1007/s12517-017-3250-3
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发表时间：
2017-12
影响因子：
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通讯作者：
N. Olasunkanmi;O. Bamigboye;A. Aina
中科院分区：
文献类型：
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作者：
N. Olasunkanmi;O. Bamigboye;A. Aina
本报告详述了铁矿石地球物理勘探的结果，其中包括垂直磁场强度和重力测量，以描绘存款的几何形状和深度范围，并为Agbado-Okudu的钻探前目的获取定量和定性信息。它位于Lokoja-Jakura大理石采石场附近，距离Jakura约3公里，位于尼日利亚Kogi州的低纬度前寒武纪基底复合区。在该存款上沿沿着16条导线共进行了517个磁测点的测量，沿沿着11条剖面在东北-西南方位进行了330个重力阅读。磁重数据增强包括线性回归曲线拟合和快速傅里叶变换，利用Gosoft Oasis Montaj软件的可扩展性，构造剩余磁异常、剩余重力异常、解析信号振幅、不同谱指数下的欧拉反褶积、功率谱和震源参数图像。RM和RG异常的解释揭示了正异常与铁矿存款完美相关的主要成因体，其形式为水平或缓倾岩墙，走向长度为600 m，平均宽度为110-130 m，位于该区域北部的片麻岩杂岩内，走向南部。与负异常相关的第二个成因体，推断为一个垂直/近垂直的薄板走向东北-西南与花岗岩和石英侵入体相吻合。NW-SE和E-W向线性构造走向符合尼日利亚已知构造走向的Kibarian和Liberian造山旋回，表明该铁矿存款受构造控制。据估计，震源深度范围为≤ 2-24 m和37.5-60 m，分别被视为浅深度和较深深度。建议进行10个深度在50米至100米之间的垂直钻孔，其中5个需要优先注意，以确定主要致病体的厚度。
This report details the result of geophysical exploration for iron ore; which involved vertical magnetic intensity (∆Z) and gravity measurements, to delineate the geometry and depth extent of the deposit and acquiring quantitative and qualitative information for pre-drilling purposes in Agbado-Okudu. It is located about 3 km from Jakura along Lokoja-Jakura marble quarry and within low latitude precambrian basement complex district of Kogi State, Nigeria. A total of 517 magnetic measurement points along 16 traverses and 330 gravity reading along 11 profiles on the deposit in northeast–southwest azimuth were undertaken. The magnetic and gravity data enhancement involved linear regression curve fitting and fast Fourier transform, which were used to construct residual magnetic (RM) and gravity (RG) anomalies, analytic signal amplitude, Euler deconvolution at varying spectral indices (SI), power spectrum, and source parameter image (SPI), using the submenu of Geosoft Oasis Montaj software. Interpretation of the RM and RG anomalies revealed a primary causative body which perfectly correlates the positive anomalies and iron ore deposit, in form of a horizontal or gently dipping dyke with strike length of 600 m and average width of 110–130 m, within the gneiss complex in the north and trending south of the area. A secondary causative body associated with the negative anomalies and inferred as a vertical/near vertical thin sheet striking northeast–southwest coincided with the granitic and quartzitic intrusion. The NW–SE and E–W lineament trend conformed Kibarian and Liberian orogeny cycles of generally known structural trends in Nigeria, which shows that the iron ore deposit is structurally controlled. Depths to sources were estimated within range ≤ 2–24 m and 37.5–60 m, regarded as shallow and relatively deep depths, respectively. Ten vertical boreholes ranging in depth between 50 and 100 m are recommended, five of which require a priority attention to ascertain the thickness of the primary causative body.