SUN Tian-qi1, ZHANG Ju-quan1*, WANG Ji-zhong2, GAO Xin-yu1, WANG Yi-qi1, LI Ya-qi1, WANG Lin-xuan1, XU Cui3
（1. Resource College, Hebei GEO University, Shijiazhuang 050031, China;
2. School of Gemology and Materials Technology, Hebei GEO University, Shijiazhuang 050031, China;
3. Laboratory, Regional Geological Survey Institute of Hebei Province, Langfang 065000, China）
Abstract: This paper has carried out detailed analyses of compositions of magnetites from ores and intrusive rocks in the Baijian Iron Deposit in the Handan-Xingtai Area. Based on the genetic mineralogy study, it is believed that the Baijian Iron Deposit was mainly formed by the contact metasomatism, rather than the ‘ore magma’ injection. Under favorable fault tectonic conditions, the iron-rich magmatic hydrothermal fluid filled into the contact zones and fractures of wallrocks, resulting to the contact metasomatism of the carbonate wallrocks and the formation of skarn Fe deposit. The study shows that the magnetite in the deposit is mainly euhedral to subhedral crystals, with part of them are replaced by hematite, pyrite and chalcopyrite. The alterations of the wall rocks are dominated by skarnization and albitization, with the zonation of alteration. Compared with magnetite in intrusions, the magnetites in ore bodies are rich in Mg, Mn, Si, Al, and Ca, but poor in Fe2+, V, and Cr, and obviously different to compositions of the typical ‘ore magma’ magnetite；Based on genetic diagram and covariant diagrams of the cation numbers in a unit molecule of the magnetite obtained by calculation, it is found that there are significant negative correlations between Mg, Mn and. Fe2+, and between Si and. Fe3+ contents, but positive correlation between Ca and Si contents. In addition, the non-redox reaction occurred in process of mineralization could also explain the occurrence of stomatal ores in the upper part of orebodies in the deposit. The differences and correlations between two elements of them in compositions of magnetites and the occurrence of non-redox reaction display the characteristics of typical skarn iron deposit.
Keywords: Baijian iron deposit; contact metasomatism; magnetite; genetic mineralogy
ACTA MINERALOGICA SINICA Vol. 39, No.1, 2019, page 31-40
