Study On Geophysics Methods For Iron Ore Exploration In Southern Peru

Iron is important material foundation for national economy and social development. With the development of national economy in recent years, the demand of the steel material is increasing quickly, the gap comparing internal production capacity of iron mine to the demand for iron mine stone in the steel industry become bigger. Facing this trend,"walking out" to explore and develop the foreign iron mine resources, building up a group of iron mine supply base overseas are pressing for our country's steel industry to acquire iron mine resources from foreign countries long-term, stably, safely, then lower the cost of the whole national economy develops. Peru is rich in iron resources, which is one of the most important investment target of China. Geophysical methods are rapid and effective ones for iron ore exploration. There is no comprehensive study of the geophysical method for iron ores exploration in Peru. It is an urgent need to do this work. Funded by Junefield Mining Institute in Central South University, the geophysical prospecting methods are studied for acquiring new advancement for iron ores exploration. The magnetic exploration method is primarily used, supplemented with IP methods. Because of special geological conditions, geophysical environment and large workload, particular characteristics are obvious in geophysical methods choice, data processing, conversions and interpretation. Methods are studied of the magnetic anomalies process and conversion methods, Dual-Frequency Induced Polarization information extraction methods and the data pre-process programming. The geophysical methods and technical procedures for iron ore exploration is summarized. Then work of metallogenic prognosis for different types of iron deposits is carried out in southern Peru.Research are as follows:It is introduced of distribution and types of iron ore resources in Peru, which is divided into three zones:the coastal zone of iron ore; the Andean zone of iron ore; the eastern zone of iron ore.The structural information and outline map of aeromagnetic structure is prepared by a series of data processing and analysis work, including preprocessing aeromagnetic data, reduction to pole at low latitudes, inversed reduction to equator, derivation, continuation, gradient modules and so on. By analyzing the dependence between structure and iron ore, comparing aeromagnetic map and the known iron ores, perspective iron ores zones are outlined. Because of the large amount of magnetic surface profiling and data, the preprocessing of raw data is automated by coding the programs using VB and batch programming languages. Peru is located at low geomagnetic latitudes environment (-12°<I0<20°), it is analyzed of the characteristics of Peru's position in the global geomagnetic field. Those are studied of the magnetization direction conversion methods and field source separation technologies at low geomagnetic latitudes. Those methods are proposed by theoretic analysis, models calculation. In actual projects, reduction to equator inversed, the first-order horizontal and vertical derivative modules, anomaly difference method stroked by analytic continuation, weighting factor method for reduction to pole at low geomagnetic latitudes are used.The DFIP method is applied as a complementary method to test the magnetic anomalies. Based on the experimental work of the DFIP method, it is analyzed of the "disconnect" phenomenon of central gradient array, the influence of the infinity electrodes position to the measurement results. Then a computer program is prepared to process the DFIP raw data automatically using VBA.Those are analyzed of the geophysical characteristics and potential reserves prospecting of two iron deposits. One type is hydrothermal contact metasomatic iron deposit, taking the Morritos iron deposit as an example.18covered veins are prospected. Another type is known as iron oxide copper-gold iron deposit, taking the Marcona and Pongo as examples. By analyzing similarities and differences of the two ores, making outline map of structures by processing ground magnetic survey data, the metallogenic prognosis in surrounding zones are carried out.