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Characteristics And Genesis Of The Songhu Iron Deposit In Xinjiang Province

Posted on:2016-06-07Degree:MasterType:Thesis
Country:ChinaCandidate:Y XuFull Text:PDF
GTID:2180330461494928Subject:Geological Engineering
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The Songhu iron deposit is located in the Awulale iron metallogenic belt, western Tianshan in Xinjiang. It is typical in diversity of ores and complexity in mineralization. On the basis of previous studies, geological and geochemical studies have been carried out on the deposit, with focuses on discrimination of its alteration and mineralization characteristics, division of ore types and periods with stages, and interference of its mineralization processes.Field investigation and microscopic investigation indicate occurrence of the Songhu iron deposit in the Lower Carboniferous volcanic- sedimentary rocks of the Dahalajunshan Group with lithologies of andeside, dacite, tuff, and tuffaceous sandstone. There occurs a discordant contact between major orebodies and host wall rocks. Iron ores may be divided into three types of ore pulp, altered rock, and hydrothermal vein. The ore pulp ore is characterized by honeycomb and banded structures, the altered rock ore by disseminated and taxitic structures, and the hydrothermal vein ore by fine vein and network structures. Wall rock alterations widely occurring in the Songhu orefield include chloritization, epidotization,actinolitization, magnetitization, pyritization, silication, and carbonation. The K-feldspathization is spread in the orefield. In contrast, the chloritization,epidotization, actinolitization, and magnetitization occur as belts, silication and carbonation as veins, and pyritization as dots.Based on veins penetrating combined with mineral assemblage and texture and structute, mineralization process of the Songhu iron deposit can be divided into ore pulp,volcanic hydrothermal, and supergene periods. The ore pulp period consists of oxide and sulfide stages, and the volcanic hydrothermal period is composed of feldspar- chlorite- magnetite, sulphide, and carbonate stages. The supergene period includes a transformation stage.. Formation temperature of ores is defined in the range of 500 ℃ ~ 700 ℃ during the ore pulp period, and about 400 ℃ during the volcanic hydrothermal period.All of the data presented in this thesis support an origin of the Songhu irondeposit via ore pulp mineralization superimposed by volcanic hydrothermal mineralization. The ores of the ore pulp type was formed by cooling and crystallization of ore magma resulted from magma dissolution, the ores of the altered rock type by replacement of the volcanic rocks by volcanic hydrothermal solution,and those of the hydrothermal vein type by filling and crystallization of volcanic hydrothermal solution in fractures.
Keywords/Search Tags:Ore deposit geology, ore deposit geochemistry, metallogenic process, ore magma-hydrothermal compound iron deposit, Awulale in Xinjiang Province
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