Buried Depth Of Archean Crystalline Basement And Concealed Iron Ore In Anshan-Benxi Region

Anshan-Benxi area is one of most important banded iron formation(BIF) mine areas in our country. BIF main hosted in Archean Yingtaoyuan group and Cigou group. At present, the exploitable iron ores in surface and shallow have been mining. But the buried depth of basement in some areas which covered by cap rock is not clear. These areas have some prospecting potential. In recent years, Dataigou iron provides a reference for the discovery concealed iron ore through the magnetic anomaly. Previous studies of archean rock in Anshan-Benxi region are mostly for the lithology and geological characteristics. But for archean crystalline basement spatial distribution form and buried depth yet have not detailed study. According to 1:200,000 magnetic anomaly shows that there are many high magnetic anomalies areas in Anshan-Benxi region. These areas have potential for prospecting.This paper studies the buried depth of archean crystalline basement in Anshan-Benxi area, by analyzing 1:200,000 gravity and 1:200,000 magnetic anomaly field, combining with the borehole data and measured density data, using 2-D man-machine interactive inversion, 3D geological surface modeling, 3D magnetic susceptibility inversion method. The studies acquired some new understandings. These provide useful information for the study of deep geological and mineral resources evaluation in Anshan-Benxi region. The main knowledge and results achieved are as follows:(1) Draw the contour map of archean crystalline basement in Anshan-Benxi region. The depth of archean crystalline basement are 0 ~ 4500 m. Shallow depth areas are mainly Neoproterozoic cap rock coverage which mainly growth in the southwest of Benxi and the northeast of study area. These areas have the potential to find concealed iron ore.(2) Build the 3D model of achean crystalline basement in Anshan-Benxi region.(3) Predicted the location of concealed iron ore in Anshan-Benxi region. Obtained the 3D shape of concealed iron ore in Pingdingshan area by using 3D magnetic susceptibility inversion method.(4) Summarized 4 structures of achean crystalline basement. 1, supracrustal rocks-granitic gneiss type; 2, granitic gneiss-iron bearing formation residual mass; 3, archean basement rocks floating in the Yanshanian granitic intrusions on; 4, large areas of Yanshanian granite intrusions.