Indication Of Mineralization Of Genetic Mineralogy Characteristics In The Huakou Silver Polymetallic Deposit,Shaxian,Fujian Province

The Huakou silver polymetallic deposit in Shaxian is a typical medium-low temperature hydrothermal deposit.It is diffcult to recognise the mineralization regularity of this deposit because the basic researches about the deposit are not enough.Based on the field observation and indoor petrographic studies,this paper mainly focuses on the study of characteristics of metal sulfides on the crystal structure,the composition and the sulfur isotope,combines with the study on characteristics of ore fluids,to analyze the indicative function about mineralization.Through these studies,this paper discusses the deposit's genetic model and its metallogenic prognosis.The research results list below:1.According to the characteristics of mineral mineragraphy in orebodies,it is recognized that the metal mineral formation sequence of this deposit:the pre mineralization pyrite ? pyrrhotite ? the mineralization period pyrite ? the early generation chalcopyrite?sphalerite?the early generation galena(the later generation chalcopyrite)? the late generation of galena(matildite)? native silver,argentite and other containing silver minerals?the late mineralization pyrite.2.The crystal structure of metal sulfides in the orefield shows that pyrrhotites are mainly monoclinic-pyrrhotite,and the main formation temperature of pyrrhotites according to the structure of the typomorphic is slightly lower than 254?.3.The composition of metal sulfides show that magmatic hydrothermal characteristics of these metal sulfides is obvious.The study on distribution of silver of metal sulfides proves that the galena is compactly connected with the silver.It indicates that the silver in the deposit is in two forms as isomorphism-phase and independent silver minerals.4.The 834S value of the sulfide in Huakou orefield tends to 0,which indicates the sulfur source of metal sulfides is single with the characteristics of deep magma sources.5.The characteristics of genetic mineralogy,combined with the fluid inclusion study,indicate that the Huakou silver polymetallic deposit is middle and low temperature magmatic hydrothermal vein type deposit.The characteristics of genetic mineralogy also indicate that there are two stages in the formation of the deposit:The early mineralization stage which its temperature concentrated in 200?300 ? is the main mineralization stage of Pb,Zn,Cu.The late mineralization stage is the main ore-forming stage for Ag(Bi),during this stage,the temperature is concentrated at the range of 120?200?.6.The Correlation study of the metallogenic elements indicates that independent silver minerals are the main factor to determine the degree of silver mineralization in the deposit.In addition,the silver-rich liquid in the late ore-forming process continued to migrate,and this phenomena show the ore-forming fluid trajectory,which is of guiding significance for further ore prospecting work.7.The comprehensive study shows that the metallogenic condition of the Huakou orefield is advantageous.There is some prospect and risk in the area of metamorphic rocks.The peripheral areas of the orefield have good prospect for ore prospecting because of the favorable conditions for ore forming.