Qian'an iron geochemistry of ore genesis of the instructions

Title: Qian'an iron geochemistry of ore genesis of the instructions
　　Author: Ding Wenjun
　　Degree-granting units: China University of Geosciences (Beijing)
　　Keywords: BIFs;; Qian'an;; geochemistry;; trace elements
　　Summary:
　　Different scholars have Qian'an area of ​​Precambrian iron ore deposit geology, petrology and geochemistry in areas such as in-depth study, but its source has not conducted into the mineral depth. Qian'an Xingshan in 2006 first discovered the rich deposits of iron ore body large, but its cause is unknown. This has taken the Xingshan Qian'an two horses rare earth magnets and two representative of the rich ore deposits, ordinary ore, gneiss, mixed granite, pegmatite about 100 samples, through its constant, trace, rare earth and the earth isotopes chemical characteristics of research, restore its original rock, into the mineral's origin and cause of high-grade ore.
　　Qian'an area constant element magnetite-quartzite rock to restore the original diagram shows the original rock is basalt, which TFe2O3 and SiO2 have a good negative correlation, the trace element depleted Nd, Ta, the magnetite δ18O are basic - ultrabasic range of rock δ18O values ​​in order to infer the original rock is basalt; and the original rock is rock rhyolite and sedimentary rocks, and magnetite-quartzite rock which does not have a genetic link. Pegmatite and gneiss constants, and distribution of trace elements and REE contents similar to infer that it is gneiss formed through hydrothermal transformation; the mining of granite and gneiss mixed constant, consistent with the distribution of trace elements and rare earth elements, inferred its the same protolith.
　　By common ore minerals and rich Qian'an constant, trace elements and rare earth elements, the results show that their chemical composition mainly by Fe2O3 (T), SiO2 composition, and have low Al2O3 and TiO2 content, indicating that its formation is almost no detrital material to join. And by the PAAS normalized REE distribution patterns show the loss http://www.chinamagnets.biz/Neodymium/Ball-Neodymium-Magnets.php of light rare earths and heavy rare earth enrichment of features, or both ordinary mineral-rich ore, have positive Eu anomalies, the Co / Zn and Ni / Zn ratio and similar hydrothermal characteristics, indicating that the formation of a high-temperature hydrothermal join; the Y / Ho> 44, Y positive anomaly that causes the seawater; δLa indicating no terrigenous join; LaN / YbN <1, that both the water feature , there are hydrothermal features, all of these data show Qian'an iron ore material source for the sea and hydrothermal, and other local sources of the same BIF iron minerals.