井中三分量磁测在鲁西大张深覆盖区铁矿勘查中的应用

Application of Three Component Magnetometry in Well in Iron Ore Exploration in Dazhang Deep Covering Area in Western Shandong Province

近年来,在山东省德州市东南部深覆盖区的矽卡岩型铁矿勘查工作取得重大找矿突破,相继发现了李屯、大张、潘店铁矿床;该区找矿工作中使用的“地质—磁法—重力—电法—地震—钻探—测井—综合研究”等找矿方法效果明显。大张地区矽卡岩型铁矿成矿地质条件优越,即该区奥陶纪碳酸盐岩地层广泛分布,燕山晚期中基性侵入岩发育,构造活动显著。以往大张异常西半环地区勘查工作取得了良好找矿成果,而对该异常东半环则尚未进行异常查证。本次研究在总结大张地区矽卡岩型铁矿成矿规律的基础上,在大张异常东半环开展了异常查证工作,施工的DZK2钻孔虽未见矿,但井中三分量磁测工作在该孔揭露的奥陶纪地层和岩体接触带处发现了矿致异常,推断其为一盲矿体,由此表明大张异常东半环亦有较好的铁矿找矿潜力。井中三分量磁测工作成果表明该勘查手段在矽卡岩型铁矿勘查工作的必要性和有效性。

In recent years,great breakthroughs have been made in the exploration of skarn type iron ores in deep covering area in southeast of Dezhou city in Shandong province.Litun iron deposit,Dazhang iron deposit and Pandian iron deposit have been discovered successively.The effect of prospecting methods,such as"Geology—Magnet—Gravity—Electricity—Seismic—Drilling—Logging—Comprehensive study"is obvious in the prospecting work in the area.The ore-forming geological conditions of skarn type iron ore are superior in Dazhang area.The Ordovician carbonate strata are widely distributed in the area.The middle-basic intrusive rocks developed in the late Yanshanian.The tectonic activity is significant.In the past,good prospecting results have been obtained in the west half ring area of Dazhang anomaly,but the east half ring area of the anomaly has not been verified.On the basis of summarizing the ore-forming regularity of skarn type iron ore in Dazhang area,anomaly verification work has been carried out in the east half ring of Dazhang anomaly.Although no iron ore is found in DZK2 borehole in the area,a mineralized anomaly is found in the contact zone between Ordovician strata and intrusive rocks exposed by three component magnetometry in borehole,which is inferred to be a blind orebody.It is showed that the east half ring of Dazhang anomaly also has a good prospecting potential for iron ore.The application of three component magnetometry in borehole in this area proves the necessity and effectiveness of this exploration method in the exploration of skarn type iron ore.