| The Dabaozhuang Fe-S deposit is located in western of Luzong areas and consists of medium Fe, lagre S orebodies. Dabaozhuang is an ideal example of studying hematite in porphyritic deposit because of massive hematite mineral in Dabaozhuang deposit and it’s similar to Gushan iron deposit. Based on the field work and petrography of hematite in Dabaohzhuang deposit we suggested that main ore structure include massive and disseminate.The hematite is divided into three types according to the mineral structure and sequence:fine granular (Typel) formed earlier, fine crystal, assemblages and unable to figure out single crystal; acicular (Type2):in distributed in fine granular assemblages, euhedral crystalandthe rationof length and width is more than tenfold; spatulate pattern (Type3) bigger thanTypel and mostly are euhedral crystal;Based on petrographic investigations from polished thin sections, several representative hematites were selected for in situ trace element analyses, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The results show that Ga, Nb, Sn, Mg, Al, Ti, V, Mn and Co elements in minerals are higher than detection limit, Li, Ca, Cd, Gd, Hf, Ta and Au elements below the detection limit. The results of Cr, Sr, As, Cu, Pb and Zn elements are partial higher than detection limit. According to the LA-ICP-MS test, we know that Typel and Type2 develops inclusion. The analysis of results indicates that the trace elements in different kinds of hematite samples have correlation, such as Al vs Ga, Co vs Mn, Mg vs Mn and Ti vs Sn diagrams of hematite present unanimous correlation, Al vs Sn diagrams opposite correlation, while Ti and V without obvious correlation. The elements distribution and microscopictre on ship of Typel and Type2 hematite indicated that both of them form of same fluid. Low Ga content of Type3 may reflect the weak water-rock interaction. We use trace elements classfication diagram of magnetite due to without establishing trace elements genetic discrimination of hematite and we found that magnetite classification diagram is not suitable for hematite. But the characteristics of trace elements of hematite and hydrothermal origin magnetite are common, suggesting that Dabaozhuang depositis belong to the low-middle temperature hydrothermal, and also inherit some features of early high temperature stage of magnetite apatite deposit. |
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