Geological Characteristics And Genetic Mineralogy Of Quyang Rutile Deposit,Hebei Province

The Quyang rutile deposit,approximately 5 kilometers southeast of the Quyang County,is located in the Xiaomu Township,Quyang County,Hebei Province.The Quyang rutile deposit,tectonically located on the side of the Trans-North China Orogen at the junction of the East Block and the Trans-North China Orogen,is a large-scale rutile deposit discovered in the Hebei Province in recent years.Since the Quyang rutile deposit was discovered,much attentions have been paid to its geological feature,spatial distribution of the orebodies,occurrence states of the rutile,ore-controlling condition,metallogenesis and resources potential.Hence,on the basis of previous studies,we select the Quyang rutile deposit to make a systematic research on the geological characteristics of deposits,petrography,genetic mineralogy,electron probe microanalyzer,chemical composition and phase analysis of raw titanium ores.These new data,in combination with the regional geological observations,we draw the following main conclusions.The deposit geology reveals that the outcropping strata in the mining area include the Paleoproterozoic Hutuo Group,Mesoproterozoic Great Wall System and Jixian System,Neoproterozoic Qingbaikou System,Cambrian,Ordovician,Cenozoic Tertiary and Quaternary sediments.Structurally,the mining area is characterized by a series of EW-trending anticline?syncline?and a series of NE-,NW–NNW-and EW-trending brittle faults.Thirty orebodies have been identified,hosted in the hematite–sericite quartz schist and hematite–sericite quartz conglomerate of the second-third member of Doucun Formation of the Hutuo Group,all of which occur as layered and stratiform.The ore minerals are dominated by hematite and rutile with minor ilmenite.The dominant gangue minerals are quartz and sericite with minor feldspar,epidote and etc.The rutile is associated with hematite in space,and has a gentic relationship with hematite.The multiple analysis of the ore shows that the orebodies contain the average,the lowest and the highest grade of TiO₂ of 3.96%,1.00%and 8.26%,respectively,with the average grade of industrial orebodies of 2.72%.The phase analysis of raw titanium ores reveals that the TiO₂ of the deposit mainly occurred in the rutile with a distribution rate of61%,whereas the content of the TiO₂ in the other oxides?i.e.,ilmenite?account for 39%of the total.The genetic mineralogy reveals that the typomorphic mineral assemblage of the Quyang rutile deposit are rutile,hematite,ilmenite,sericite,quartz and epidote,which indicate that they were formed in low-grade metamorphism?i.e.,greenschist facies?.Based on the color,size,crystal morphology and occurrence state of the rutile,the rutile in the Quyang deposit can be subdivided into three types.The first and third types of the rutile may be a product of the early-stage mineralization,and occurred in a intermediate-high metamorphism,whereas the second type of the rutile was commonly associated with the hematite,sericite and epidote,indicating that it was formed in the metamorphism?i.e.,greenschist facies?.Compared with the characteristics of the typical rutile deposits in China,we concluded that the Quyang rutile deposit genetically belong to the sedimentary metamorphic rutile deposit.These new data,in combination with the regional geological observations,we arrived at the metallogenic process as follows:?1?In the early Paleoproterozoic?².1 Ga?,the study area was in a rift environment and widely deposited abundant sediments;?2?Accompanying the finally amalgamation of the East Block and the West Block along the Trans-North China Orogen in the late Paleoproterozoic?1.95¹.8 Ga?,the extensive greenschist facies metamorphism promoted the enrichment of the titanium elements in this area,resulting in the formation of the rutile deposit at the Quyang.