Analysis On Geological Characteristics Of Taohua Iron Deposit Of Wushan Country In Chongqing

The geotectonic location of Taohua mining area of Wushan in Chongqing lies in Qiyaoshan arcuate-folded area in Southeast Chongqing depression-folding beam of upper Yangtze Syneclise of Yangtze para-platform.Mining area lies in NE end at Hejiaping anticline belonging to secondary fold of SE wing at Qiyaoshan anticline.The deposit is hosted in grey green and violet silty shale in the Huangjiadeng Formation of upper devonian.The orebody has a clear demarcation with the roof and bottom of orebody,and is occurred in form of stratiform and stratiform-like.Ore minerals which are about 90% in ores mostly contain hematite and siderite secondly;Gangue minaerals that have a low content in ores mostly contain quartz and hydromica and chamosite and collophanite.Impurity P mainly occurs in form of collophanite in iron ores,which usually distributes in hematite ores by form of fine briquettes and sometimes forms oolites of circle layer with hematites.The average grade of ores in mining area reaches TFe43.58%.The content of harmful component P is 0.5～1.1%,which is generally quite high.As a result,ores in this mining area become oolitic hematite ores containing high P.Ores texture mostly are pisolitic-oolitic and oolitic-sandy.Ores structure mostly are banding and massive.The formation of iron deposit mainly is controlled by the condition of lithofacies- paleogeography.This paper summarizes the condition of lithofacies-paleogeography that is beneficial to form iron deposit:①Paleoclimate condition of damp-heat impels laterization of rocks containing iron on ancient land,which provides adequate iron source;②In ralatively quite closed or semi-closed inland furumi basin and ancient coastal bay,because of their sea depth are ralative shallow,the condition of no great storms is useful for sedimentation of iron deposit;③Generally speaking,the transgression sedimentary series of shallow sea are helpful for oolitic hematite ore facies;④The iron may be mainly transported in the form of colloids and fine suspended gels or adsorbing oxides by the ancient land rivers.This area lies in metallogenic province of Western Hubei and Northwestern Hunan,which belongs to a relatively quite closed inland furumi basin and has useful condition of no invasion of great sea storms and quiet sea for sedimentation of iron deposit.The main metallogenic material Fe mostly comes from around ancient land weathered.Nearshore facies totally have the condition of building oolites,superadd containing abundant core materials.At state of suspending,various hematite micrites form hematite oolites in methods of collochemistry sedimentary.After being transformed and enriched by sea wave and tide process,these oolites form the Ningxiang-type iron deposit which is finally believed to belong to nearshore facies and upper offshore facies.The genetic type of hematite deposit belongs to syngenetic deposit.Oolitic hematites are formed by collochemistry sedimentary.