Spatial Form And Ore-controlling Factors Of Vanadium Titano-magnetite Deposits In Hongge,Sichuan

The layered intrusions in Panxi area host giant vanadium-titanium magnetite deposits which are famous all over the world.The structure features of the Panxi area are characterized by the long-lived NE trend tectonic belt and EW trend fold basement.The Hongge intrusion is one of the main mafic-ultramafic layered intrusions in the Kangdian axi tectonic belt,resulting in the beneficial metallogenetic potentiality in this area.For a long time,the Hongge vanadium-titanium magnetite deposit was identified as typical layered ore deposit.The main ore bodies of the Hongge deposit occur as paralleled layered or layered-like in the middle to bottom part of the intrusion,and the ore bodies are cutted by faults.Through systematic study on previous results,in combination with verification after detailed field investigation,the author proposes the following points:(1)The Hongge deposit is a vanadium-titanium magnetite deposit.The orebodies are hosted in the dolostone of the Sinian Dengying Group,medium-to coarse-grained gabbro,(olivine)pyroxenite,fine-grained gabbro,basalt and granite.The ore types include:(1)Massive iron-rich ore,the gangue minerals comprise minor plagioclase,hornblende,biotite and sulfide;(2)Gabbro type iron ore,the gangue minerals comprise mineral assemblages of gabbro with gabbro texture;(3)(Olivine)pyroxenite type iron ore,the gangue minerals are pyroxene,olivine,plagioclase and hornblende.(2)The shape and occurrence of the ores in the Hongge deposit are complicated,and the ore bodies display various spatial distribution.The layered-like and lenticular ores,they are hosted in gabbro and crop out in level with rhythmic bedding;peviform or multi-peviform ores;irregular ores crop out along the migration chanel of magma(or ore forming fuild).(3)The ore-controlling factors include:(1)Magmatic crystallization differentiation,V-Ti oxide enriched melts formedafter fractional crystallization from the magma chamber and then intrude the dolostone to form the iron ores;(2)Injection of ore forming fluid,the V-Ti oxide enriched fluid derived from the deep or magma chamber inject into the dolostone,basalt and weak belt of the intrusion along the migration channel of magma and contact zone of intrusion;(3)The previous ores transformed by the emplacement of syenite and granite magma which are formed by the evolution of the same sourced magma.In the upper part of the intrusion,the syenite intrusions and dykes are more injected.Granites are more likely occurred in the edge and head of the gabbro intrusion,the iron ores in the granites crop out as crossed residual or xenolith;(4)The disruption on ores by fault after mineralization,the fault displacement is usually less than 50 m.