"Pamir-type" iron deposit is one of the most important categorized magnetite deposits in West Kunlun, Xinjiang, and its metallogenesis is still unclear. Previous studies on geological characteristics, ore-forming ages suggested that these magnetite deposits were obviously distinguished from those typical BIFs magnetite deposits globally. Wengjile magnetite deposit and Zileyi magnetite deposit, two representative magnetite deposits in this region, were selected in this study. Litho geochemistry of admellite and wall rocks, ore-forming minerals characteristics, trace element geochemistry and in situ Pb-Pb isotopic composition of magnetite were discussed in this study to explore the metallognesis and ore-forming background of "Pamir -type" iron deposit. Wengjile magnetite deposit lies in the contact zone between Wengjile biotite-admellite and Paleoproterozoic Bulunkuole Group biotite quartz-schist. The deposit is closely associated with Wengjile biotite-admellite in spatial and temporal. Geochemical characteristic of Wengjile biotite-adamellite is higher in SiO2 (69.10% similar to 74. 51%), Al2O5 (14.24% similar to 16.13%), K2O(4.46% similar to 4.91%) and Na2O (3.82% similar to 4.29%), and lower in MgO (0. 25% similar to 0. 69%), CaO (1.1% similar to 1. 99%) and TiO2 (0.139% similar to 0.398), and has a very narrow variation of Na2O/K2O (0.80 similar to 0. 87) and unanimous Rittmann Index (2.20 similar to 3. 24). Aluminum saturation index (1.44 similar to 1.51) suggested it belonged to a weak peraluminous rock. Total Rare Earth Element is higher (170.4 x 10(-6) similar to 400.5 x 10(-6), and delta Eu (0.44 similar to 0.87) is a strong negative Eu anomaly. The rocks contain variable contents of trace element in the trace element spider diagram, but generally have a similar variation trend such as systematic enrichment of LILE such as K, Rb, Sr, Ba (where Sr > 421 x 10(-6),Ba > 853 x 10(-6)) and REE but depletion of HFSE such as Nb, Ta, P and Ti. The content of the major oxides in Bulunkuole biotite quartz schist are SiO2 (57.07% similar to 60. 99%), and Al2O3 (14.46% similar to 8.61%, MgO (2.22% similar to 3. 60%), CaO (1.12% similar to 2. 86%),TiO2 (0.75% similar to 1. 12%), and are rich in REE (146.0 x 10(-6) similar to 200.5 x 10(-6), and has a median Eu anomaly (delta Eu is 0.65 similar to 0. 74). Trace element analyses suggested there is a lower Rb/Sr ratio (0.16 similar to 0. 89) and obvious depletion of Th, Zr, Hf, Nb, Ta, P and Ti but apparent positive anomaly of barium, which may suggest that the rock has the characteristics of aluminum-rich sedimentary formed in the environment of margin of ancient continental. The geochemical similarity between Wengjile biotite-admellite and Bulunkuole biotite schist demonstrated there is a genetic relationship between them. Zircon LA ICP-MS U-Pb dating of Wengjile biotite-admellite suggested the rocks formed around 15.0 +/- 0.3Ma and 15.4 +/- 0.2Ma. Trace element geochemistry of magnetite using LA ICP-MS indicated that magnetite from Wengjile magnetite deposit has higher Si, Mn, Zn, Pb, Hf, Sn and variable Mn and Ga, and magnetite from Zileyi magnetite deposit has relatively higher LILE such as Mg, Al, Ti, V, Co, Ni, Sc and lower variable Mn and Zn. In contrast, the range of variation of trace elements in magnetite from the Wengjile magnetite deposit is relatively larger, while the range of magnetite in the Zileyi magnetite deposit is relatively small. The Pb-Pb isotopes of the magnetite from the two deposits are distinctly different. The Pb-206/Pb-204 of the magnetite from Wengjile magnetite deposit varied from 9. 0699 to 41. 4030 with an average value of 20. 4808, and Pb-207/Pb-204 varied between 11.0454 and 34. 1993 with an average of 17. 5573; and Pb-208/Pb-204 varied between 28. 6800 and 84. 1533 with an average value of 44. 8547. The Pb-206/Pb-204, Pb-207/Pb-204 and Pb-208/Pb-204 of the magnetite from Zileyi magnetite deposit are lower. The calculated isotope ratios of Pb-206/(204) Pb varied from 0.67 to 1.37 with an average of 1. 16; (208)pb/(206)ph varied from 1.85 to 3 61 with an average of 2. 24, and Pb-208/Pb-204 between 2.36 and 3.04, with an average of 2.56. Pb-Pb isotope results indicated that the magnetite from the Wengjile magnetite deposit may be related to biotite-adamellite and is hydrothermal but magnetite from Zileyi was not. In summary, there are not only deposits -related to sediment process, but also some hydrothermal magnetite deposits, which related to magmatic hydrothermal activity in the Tashkurgan region.
