1. data collection
Collect geological, mineral and gravity data, geological inspection certificate data, physical property data, exploration right data, mining right data and working degree data in the study area extensively, so as to determine the nature of aeromagnetic anomalies more effectively.
2. Arrangement of aeromagnetic anomalies
Anomalies related to magnetite were screened from the national aeromagnetic local anomaly database (1 1000), aeromagnetic anomaly cards (more than 400) and aeromagnetic reports over the years, and the known/inferred aeromagnetic anomaly distribution map of iron ore was compiled.
Fig. 5- 1 working degree map of iron ore comprehensive survey area in Luannan-Zunhua area, Hebei Province
1- large, medium and small iron deposits; 2— Workspace and code of large-scale investigation project (see Table 5-1for details); 3 —— Iron ore prospecting completion area in Luannan-Zunhua area; 4— Color contour map of aeromagnetic δT anomaly
Fig. 5-2 Work Flow Chart for Optimization of Iron Ore Prospecting Target Area
Fig. 5-3 Distribution Map of Aeromagnetic Optimized Iron Ore Target in Important Metallogenic Belt of Shanxi-Hebei-Liaoxi Iron Mine
3 preparation of iron ore mining areas and exploration (mining) rights distribution map.
Based on the map of iron ore resources in China (1:5 million) (Zhao et al., 2005), North China1:kloc-0/.50 million,1:200,000,1:50,000, etc.
The distribution map of iron ore exploration and mining rights collected up to 2009 is superimposed on the iron ore distribution map.
4. Aeromagnetic map compilation
Compile aeromagnetic △T profile, aeromagnetic △T isoline, aeromagnetic △T residual anomaly profile, aeromagnetic △T polarization isoline and other related maps to provide basic maps and potential field conversion maps for analysis and research.
5. Study on regional metallogenic geological background and metallogenic regularity.
Through the study of regional metallogenic geological background and metallogenic regularity, the information of ore-controlling conditions is extracted, which provides geological structure basis and basis for qualitative interpretation of aeromagnetic anomalies.
6. Study on typical mineral deposits
Based on the study of typical deposits in important metallogenic belts, a geological-geophysical prospecting model for determining iron ore prospecting indicators is established.
7. Aeromagnetic anomaly screening
According to the geological-geophysical prospecting model and iron ore prospecting criteria, the low-slow anomalies or strong magnetic anomalies that were not numbered in the past were reinterpreted, and the inferred interpretation results of previous aeromagnetic anomalies were reviewed and reinterpreted to screen iron ore-induced anomalies.
8. Supplementary measurement of physical property data and detection of suspected ore-induced anomalies
In important iron ore-forming areas, in areas that need quantitative interpretation but lack physical property data, the measured physical property data are supplemented; The aeromagnetic anomaly reconnaissance has a good anomaly shape and a good prospect for iron ore exploration, but it has not been verified yet.
9. reinterpretation of key aeromagnetic anomalies
Qualitative and quantitative interpretation of key aeromagnetic anomalies.
According to the geological, mineral and geophysical data of important metallogenic belts, the selected aeromagnetic anomalies are analyzed in terms of metallogenic geological structure, magnetism, topography, abnormal characteristics and comprehensive geophysical methods, and qualitative explanations are given.
2.5D man-machine interactive quantitative calculation is carried out for key mine-induced anomalies, and the projection range, buried depth, width and occurrence of the top of magnetic ore body on the surface are determined.
10. Optimization of iron ore prospecting target area
Through the analysis of ore-controlling conditions, the study of prospecting criteria and the qualitative and quantitative explanation of ore-induced anomalies of key iron ores, the aeromagnetic anomalies with prospecting prospects are screened out and the prospecting target area is delineated.
In a word, the optimization of iron ore prospecting target area focuses on the screening of ore-induced anomalies. Through screening, analysis, research, re-inference and re-screening of aeromagnetic anomalies, aeromagnetic anomalies which are closely related to iron ore and have good prospecting prospects are screened out. Finally, the prospecting target area is delineated according to the abnormal distribution characteristics, which provides a scientific basis for the next iron ore exploration and deployment.