安徽泥河铁矿深部找矿综合地质地球物理研究

【作者】 匡海阳；

【导师】 吕庆田；

【作者基本信息】 东华理工大学 ， 地球探测与信息技术， 2012， 硕士

【摘要】 长江中下游成矿带是我国东部重要的铁、铜多金属矿产资源基地，使用现代地球物理探测技术对该成矿带典型矿床深部结构进行探测，以矿体（容矿岩体）与围岩物性差异为基础，建立地质-地球物理找矿模型进行隐伏矿体定位预测，对认识深部矿床成因、总结找矿方法和深部找矿的实践具有重要意义。本文主要立足于全国深部矿产资源勘查现状，选择长江中下游典型深部隐伏矿床—泥河玢岩铁矿为个案，从深部找矿的角度出发，进行地质研究和综合地球物理探测研究。总结了泥河铁矿区域成矿地质背景，分析了泥河铁矿成矿规律，在此基础上，对泥河铁矿进行了重、磁、电综合地球物理探测，并对数据进行了处理、反演和解释，最后，通过重、磁3D反演与电磁测深3D成像，结合成矿模式建立了泥河铁矿3D地质地球物理模型，并提出了泥河铁矿深部综合找矿模式。通过研究，本文取得了如下认识及成果：⑴总结了泥河铁矿区域成矿地质背景，系统分析了该区的成矿作用与成矿规律。根据前人研究总结了泥河式“玢岩铁矿”的成矿模式：泥河铁矿床是与燕山期早白垩世闪长玢岩有关的火山—次火山岩浆热液矿床，矿床的形成受火山构造、基底膏盐层等控制和影响。⑵对泥河矿区1:5万重力数据和1:1万高精度地面磁测数据进行了二阶趋势分析、化极、解析延拓等处理，得到了矿区局部布格重力异常图和局部化极ΔT磁异常图。二者联合解释发现，位场分离后的重磁局部高值异常区吻合极好，体现明显的“重磁同高”特征。⑶对泥河矿区进行了多种电磁测深法（AMT、CSAMT、TEM）探测，并对数据进行了去噪、静态效应校正、近场源校正等处理，对处理后的数据进行了二维、一维反演。结合地质资料和重、磁数据，对矿区电磁探测结果进行了解释，电磁反演剖面的电性特征刻画了砖桥组火山岩地层分布，结合重磁高值异常，分辨出闪长玢岩体的隆起部位和基本形态，预测出矿体的赋存位置。⑷在已有地质资料和钻孔约束的条件下，采用人机交互的方式，重磁联合反演了泥河铁矿体的3D模型。反演结果反映了矿体的三维空间分布，直观显示出矿体的位置、形态及走向等特征。从反演结果可知矿体基本走向与地层走向一致，为北东向。磁铁矿体埋深-600~-1100m范围内，主要位于西南部，黄铁矿主要集中在矿区的东北部，中部少量的硬石膏，黄铁矿和石膏矿埋深相对于磁铁矿较浅。⑸将28条AMT测深数据的2D反演结果进行3D插值平滑处理，建立了矿区地下1500m范围的3D电性模型。通过对不同取值范围的3D电阻率结构体的显示，结合地质及重磁资料可以推断不同岩体分布的范围及形态，深部视电阻率值大于150ohm.m的3D电性模型在深度为-500~-800m存在的向上隆起形态与重磁3D反演结果吻合较好，推测为基岩侵入部位及形态，指示出这些隆起部位为有利的成矿区。⑹在总结前人对泥河矿区成矿地质规律研究的基础上，结合本文地球物理特征的研究，尝试建立了泥河铁矿的3D地质地球物理模型，探讨了泥河铁矿深部综合找矿模式。认为：在正确成矿理论和成矿模式的指导下，重、磁、电等多种地球物理探测手段组合运用，多物性、多参数综合解释的方法对隐伏矿体进行定位和预测是深部找矿行之有效的模式。更多还原

【Abstract】 Middle-Lower Yangtze Valley is an important poly-metallic mineral deposits base ineastern China. Prospecting the deep structure in typical deposits by advanced geophysicalsurvey methods, forming geological and geophysical model to prognosis of concealed oresbased on the differences between ore-body and surrounding rock is necessary for findingout the origin of deep deposit and strengthening different geophysics technologies inmineral exploration.In this paper, based on the present situation of deep exploration of mineral resources,we study the geologic and geophysical survey of Nihe porphyrite iron deposit, which is atypical concealed deposit in Middle-Lower Yangtze Valley. Summarized the regionalgeological background and mineralizing setting, analyzed the metallogeny, formed themetallogenic model of Nihe iron deposit; and did integrative geophysical prospecting suchas gravity, magnetic and electromagnetic prospecting, did data processing, inversion andinterpretation to every method; finally, did gravity and magnetic3D joint inversion andresistivity3D imaging, formed3D geologic-geophysical model of Nihe iron deposit, putforward prospecting model of Nihe iron deposit. After the study, this paper shows thepractice and cognition as follows:⑴Summarized geological background of mineralization and metallogeny of Niheiron deposit, established metallogenic model of Nihe porphyrite iron according topredecessor’s research achievements. Nihe iron deposit is a volcanic-subvolcanicmagmatic hydrothermal deposit which in connection with Yanshanian Early Cretaceousdiorite porphyrite, the form of deposit is controlled by volcanic structure and basement saltbed.⑵Did second-order tendency analysis, reduction to the pole and analyticalcontinuation to large scale gravity data and high-accuracy ground magnetic survey data ofNihe deposit, obtained the local bouguer gravity anomaly map and reduction magneticanomaly map. Combined the both results, the region of high value of gravity and magneticcoinciding good.⑶Conducted multiple magnetotelluric sounding method (AMT,CSAMT,TEM)prospecting, did denoising, static correction, near-field sources correction, and didtwo-dimension or0ne0dimension to the correction data. Interpreted the results ofmagnetotelluric prospecting combined with geology, gravity and magnetic data, thecharacteristics of resistivity profile traced the distribution of zhuanqiao bridge volcanicrock formation, identified the uplift position and shape of diorite porphyrite, predicted thepossibility position of ore-body.⑷Constraint with geological data and well log, did gravity and magnetic3D joint inversion to Nihe iron ore-body by human-computer interaction model. The result ofinversion reflected the distribution of ore-body in three dimension, displayed the position,shape and tendency of ore-body objectively. It shows the tendency of ore-body isconsistent with course of seam, both are north-east. The depth of magnetite in thewest-south part extending from600m to1100m underground, pyrites are mainly in thenorth-east part, anhydrite is mainly in the middle and lower than magnetite.⑸Interpolated and smoothed in3D with the results of28AMT profiles, establishedthe3D resistivity model of mining area beyond the1500m under the ground. Accordingthe different range of resistivity data volume, inferred the distribution of different rockmass combined with gravity and magnetic. The3D model of resistivity higher than150ohm.m shows the shape and position of uplift, which is in accordance with the3Dresults of gravity and magnetic, we inferred it as the position of rock body, and it in favorof mineralization.⑹Based on the research of metallogenic regularity by predecessor, combining withthe study to the geophysical in this paper, established3D geologic-geophysical model ofNihe iron-ore deposit, discussed the prospecting model: guided by metallogenic theory,multiple geophysical exploration method (such as gravity, magnetic, electromagnetic)associated use, comprehensive interpretation by multiple physical property and parameteris an efficient deep prospecting model.更多还原