Research On Geology Of Iron Deposit In Taliabu,Sula Islands,Indonesia

The studied iron ore area is a recently discovered large-scale skarn-type magnetite deposit by Chinese geologists including author in Taliabu of Sula islands in Indonesia.Sula islands belong to the northern edge of SE Asia epicontinental crust,situated in the conjunction zone between southwestern edge of Eastern Asia continental crust,Australian crust and Philippine ocean crust.It is not only an important part of circum-Pacific metallogenetic belt,but also the extension of SE Asia Sn-Fe metallogenic belt.The geological conditions in Sula islands are very favorable for mineralization,but the geological work there is in extremely low degree without any exploration.Based on the abundant first-hand information from the field geological work for the iron deposit,the typical geological features of the deposit are studied,the genetic type of ore deposit is determined,the five stages of mineralization are divided,metallogenetic factors are summarized,and prospecting criteria is established by this thesis.As a successful case quickly and accurately to find large magnetite deposits in the forested area of Southeast Asia,present research in the area of exploration and metallogenic study of skarn and ore magma magnetite deposit is of great applicative value and scientific significance.Systematical research on the deposits shows that the magnetite orebodies occur near the contact zones between granite bodies and the carbonate layers of Upper Carboniferous Pzmm strata.The wall rocks are mainly of skarn,marble and granite.The orebodies are dominantly in lenticular-like or lenticular or stratoid shapes with the average thickness of 28.4m,their strike is generally in EW direction,they are longer than 2000m and extend 48-620m along dip direction,and the dip angles are commonly 30°-45°.Iron mainly occurs as magnetite,and the average TFe grade is 35.07%.The preliminarily explored iron ore resources are larger than 0.15 billion tons.The ore minerals are of magnetite,locally containing a certain amount of sphalerite and chalcopyrite;on the earth's surface,limonitization occurs locally.The gangue mine rals are mainly composed of diopside.For the iron ores,there are granular texture and m inor metasomatic texture,lumpy structure and disseminated structure.The iron ores in t his deposit is convenient for ore-dressing,and show favorable technical performance of processing.Iron is the main element of recovery.The magnetite particles are in monocry stal embedding or intergrowth embedding,the main interlocking minerals are silicate mi nerals,e.g.diopside,and the inlaid relationship is relatively simple,mostly of regular ad joining.This research has revealed that magnetite formed mainly in oxide stage,sphalerite and chalcopyrite and other sulfides formed in sulfides stages.Skarnization is a wall-rock alteration most closely related to magnetite mineralization.While development of strong skarnization,especially the large number of diopside,tremolite and serpentine associated with magnetite,mark an important ore-hunting indicator.The skarn-type ore is the main body of the deposit associated with less important type of ore magma penetration.Now believe the ore-forming metals mainly from granitic magma by crustal melting and ore-forming fluid mainly from late-to post-magmatic hydrothermal solution.Prospecting criteria of the iron deposit in the area include indicators of the contact zone between granites and strata,geological structural signs,aeromagnetic signs,remote sensing and wall-rock alteration signs and magnetic soil signs.