山东禹城李屯地区重磁异常特征与找矿预测

doi:10.19657/j.geoscience.1000-8527.2024.008

摘要/Abstract

摘要：

近年来,山东禹城取得了富铁矿找矿重大突破,具有良好的找矿潜力,但区内尚有多处局部异常尚未查证。该区新生界厚度大(900~1100 m)、磁铁矿体埋藏深,矿体引起的地球物理异常弱,找矿难度大。为系统总结该区磁铁矿异常特征,为钻孔部署提供依据,重点剖析了禹城李屯地区航空重磁平面异常特征、地面高精度磁测异常特征,总结了矽卡岩型铁矿主要重磁异常找矿标志,主要为化极磁异常、剩余磁异常、垂向导数和总梯度模的异常中心,圈定了叠道村和于庄村2处找矿靶区。通过地震约束下的2.5D重磁剖面反演,推断了矿体赋存位置,指导部署了验证钻孔孔位,经钻探验证在禹城市李屯地区叠道村异常取得重大找矿新突破。研究成果对于该区下一步找矿勘查和其他深覆盖区矽卡岩型富铁矿找矿具有指导作用和借鉴意义。

关键词: 李屯地区, 富铁矿, 重磁异常, 找矿预测

Abstract:

Recently, significant breakthroughs have been made in the exploration of rich iron deposits in Yucheng, Shandong. However, there are still multiple local magnetic anomalies in the area that have not been verified, which have a promising ore-prospecting potential. However, the Cenozoic Erathem in this area is very thick, about 900-1,100 m, and the magnetite orebody is deeply buried, which leads to weak signals of geophysical anomaly, making it challenging to find the iron ores through surface exploration. In order to systematically summarize the abnormal characteristics of magnetite in this area and provide a basis for drilling deployment, the paper focuses on analyzing the abnormal characteristics of airborne gravity and magnetic plane and the abnormal characteristics of high-precision magnetic survey on the ground in Litun area, Yucheng, and summarizes the main prospecting signs of gravity and magnetic anomalies of skarn type iron ore, which are mainly the anomaly centers of polarized magnetic anomalies, residual magnetic anomalies, vertical derivatives and total gradient modes. Accordingly, two prospecting targets in Diedao Village and Yuzhuang village were delineated. Through the 2.5D gravity and magnetic profile inversion based on the electrical seismic constraints, we delineated two ore target areas, which can further guide the deploying the locations of the verification drilling holes. Significant breakthroughs in ore prospecting have been made in the Litun area of Yucheng City after the drilling verification of stacked-channel anomalies. The results in this study are of great significance and guidance for the future mineral exploration in this area and the search for iron-rich skarn-type ores in other deep ore hidden areas.

Key words: Litun Area, iron-rich ore, gravity and magnetic anomaly, ore-prospecting predictions

中图分类号:

P631.2

张文艳, 朱裕振, 刘雪, 汝亮, 闫冰. 山东禹城李屯地区重磁异常特征与找矿预测[J]. 现代地质, 2024, 38(01): 68-76.

ZHANG Wenyan, ZHU Yuzhen, LIU Xue, RU Liang, YAN Bing. Magnetic Field Anomany Characteristics and Ore Predictions in the Litun Area of Yucheng, Shandong[J]. Geoscience, 2024, 38(01): 68-76.

图/表 9

图1 禹城李屯地区基岩地质简图

Fig.1 Geological sketch of bedrock in Litun,Yucheng

图2 李屯铁矿0勘探线地质剖面图[13]

Fig.2 Geological section of 0 Exploration Line in Litun iron ore[13]

表1 禹城地区岩(矿)石物性参数一览[14]

Table 1 Statistics of physical parameters in Yucheng area [14]

岩石名称	密度(10³kg/m³)		磁化率(10^-5SI)		剩磁(10^-3A/m)		物性特征
岩石名称	变化范围	平均值	变化范围	平均值	变化范围	平均值	物性特征
第四系和新近系泥岩	1.71~2.11	1.93					低密度、无磁性
石炭系—二叠系泥岩、砂岩	2.62~2.71	2.66	微弱	微弱			中等密度、无磁性
寒武系—奥陶系灰岩	2.71~2.74	2.73	微弱	微弱	微弱	微弱	中高密度、无磁性
闪长岩	2.55~2.99	2.76	31.84~7244.6	2719.1	81.60~4827	862.1	中高密度、中高磁性
二长花岗岩	2.48~2.63	2.61	34.4~2648.2	1356.6	226.8~1776	991	中等密度、中等磁性
泰山岩群	2.52-3.07	2.95	400~3162	2600			高密度、中高磁性
磁铁矿石	4.20~4.81	4.26	32010~219809	63788	32938~130522	46377	高密度、高磁性

图3 禹城地区航空重磁异常特征平面图

Fig.3 Plane distribution maps of airborne gravity anomaly and aeromagnetic anomaly characteristics in Yucheng

图4 李屯地区航空重力异常特征图

Fig.4 Plane distribution maps of airborne gravity anomaly characteristics in Litun

图5 李屯地区航磁异常特征图

Fig.5 Plane distribution maps of aeromagnetic anomaly characteristics in Litun

图6 李屯地区地磁异常特征图

Fig.6 Plane distribution maps of ground geomagnetic anomaly characteristics in Litun

图7 找矿靶区预测

Fig.7 Map of prospecting for target prediction

图8 HP6线2.5D重磁震剖面联合反演剖面

Fig.8 2.5D gravity magnetic inversion profile of the line HP6

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