| The iron-copper mineralization belt of Awulale is an important Late Plaeozoicmetallogenetic belt in western Tianshan, where the characteristic of mineral resourcesdistribution is that iron deposits locate in the east and copper deposits locate in thewest. As a typical volcano-subvolcanic hydrothermal iron deposit, the medium-sizedAkesayi iron deposit is located in the center of the metallogenetic belt, which ishosted by lower Carboniferous Akeshake volcanic-sedimengtary Formation. In thisthesis, based on the predecessors`work and fieldwork of geological survey, wefocused on the study of basic geology, ore geology, element and isotope geochemistry,fluid inclusion, geochronology, mineralization mechanism, metallogenic mode andcomparation with typical volcanogenic iron deposits domestic and overseas, and themain understanding are as follows.(1) Akeshake magnetite bodies are mainly hosted in AkeShake group andesiticcrystal debris and debris tuff, tuff, a small amount hosted in quartz diorite porphyrite,the ore minerals are mainly magnetite, accompanied by small amounts of hematite,pyrite and chalcopyrite, gangue minerals are mainly feldspar, quartz, pyroxene,chlorite, sericite and carbonate minerals, etc.,which is a medium-sized magnetitedeposit.(2) The deposit consists of several ore bodies, which is mainly divided into Eastore block and West ore block. The West Mine is controlled by interlaminar cracks andfissures vein branching，with Lenticular and vein Spreading, and there are complexbranching phenomenons. East magnetite ore body segments scattered in a long strip ofvolcanic edifice, the volcanic center lithology andesitic tuff lavas, lateral turn intolava (andesite), pyroclastic rocks, ore controlled by volcano channel secondary faults,fissures control, which has complex shapes, such as elongated strips, pulse shape,lenticular distribution. (3) The ore bodies distributed in the outer ring of ancient volcanic fracture zone,the main lenticular vein distribution, tilt angle steeper. From the ore body to rock,alteration mineral assemblage evolved from medium high temperature to lowtemperature, mainly developed epidote, chlorite, prehnite, sericite, pumpellyite,biotite, actinolite, barite and other alteration minerals.(4) The REE of rock(ore) analysis showed that LREE and HREE fractionationare different significantly and belonging LREE enrichment and Eu anomalies, andsimilar with modern mid-ocean ridge, the Red Sea and other hot fluids and metal-richchemical sediments, reflecting the Akeshayi magnetite deposits are genetically relatedto submarine volcanism.(5) The test of fluid inclusions of ore of the volcanic lava types, reflecting themagnetite is in medium and low hydrothermal ore-forming eruptions in the late stageor from strong to weak period and a large number of volatile substances of lowtemperature heat phase. Showing that the main mineralization period of this area is agap during the eruption of volcanic activity.(6) The deposit can be divided into four ore–forming stages: the end of the LateDevonian rift embryonic development period; late Early Carboniferous rift peakperiod; Late Carboniferous volcanic hot liquid transformation mineralization period;Late Carboniferous late magmatic mineralization enrichment of the magma gas-liquidreplacement.(7) Combining the ore deposit geology characteristic with compared with typicalskarn iron deposits and volcanic iron deposits, conclusions have been drawn that theAkeshayi ore is a typical volcano-subvolcanic hydrothermal iron deposit.Mineralization stage throughout the whole process of volcanic lava to the volcanoclastic rock construction of formation.(8) Taking these research results, the establishment of Akeshayi iron ore depositmetallogenic mode. |
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