The Study On Fluid Inclusion Of Liangkeshu Pegmatite Iron Deposit In Altay

Altay orogenic belt located in the junctions of four countries: China, Mongolia,Russian, Kazakhstan.It is an important part of Central Asian Orogenic Belt （Sengor etal.,1993;Xiao et al.,2004）. The Liangkeshu pegmatite iron deposit in Xinjiang UygurAutonomous Region is located in Later Paleozoic sedimentary of the southern marginof Altay orogenic belt. It mainly occurs in pegmatite dikes found in the contactsbetween the monzonitic granite pluton and stratum, some in skarn. It is closelyassociated with pegmatite on space and origin, and is a newly found iron ore type.This paper studies the age of granite and inclusions within quartz about the deposit,and concludes that:（1）The LA-ICP-MS zircon U-Pb age of monzonitic granite is （376.7±1.3） Ma.The granite formed in active continental margin environment. The age limits thatLiangkeshu pegmatite iron deposit formed in late Middle Devonian.（2）The iron mineralized bodies mainly occurs in pegmatite presenting asstripped、disseminated or rounded structure. The surrounding rock altered. Forexample, albitization, epidotization, skarnization. The mineralization periods can bedivided into magmatic thermal fluid period、hypergenesis and pegmatites、skarn、quartz-magnetite three mineralization stages.（3）The main inclusions type within quartz in pegmatite is fluid inclusion of thegas liquid two phase flow.（4）The range of homogenization temperrature is156℃³67℃, the mainmineralization temperrature is between210℃and250℃. The range of NaCleqis2¹6%, the range of density is0.80⁰.95g/cm³. The range of estimated pressure is0.4-17.5Mpa.δDSMOWof quartz is between-110‰and-76‰.δ¹⁸OSMOWof quartz isbetween5.3‰and7.9‰. It indicates that the ore-forming fluids come from magmaticwater.（5）The REE within magnetite changes in a wide range. LREE is relative rich. The oxygen fugacity is high. The range of Fe₂O₃/FeO is between2.05and2.23. Theaverange of Ni/Co is1.21. It indicates the ore-forming material comes from the depthof earth crust.