大东山锡矿田矿床地质特征及矿床成因

Geological characteristics and origin of the Dadongshan tin orefield

大东山锡矿田矿化类型复杂,其中矽卡岩型锡矿规模大,可分含锡矽卡岩型和硫化物矽卡岩型.岩体区有脉状和面状云英岩产出,前者多具锡矿化,后者具钨矿化.燕山第四期花岗岩是锡(钨)成矿母岩,含SiO2 74.96%～75.28%,K2O+Na2O 7.37%～8.54%,K2O＞Na2O,与南岭地区钨锡成矿岩体具有相似的岩石化学特征.锡矿成因类型可划分为接触交代型、侵入岩浆热液型和风化矿床.根据成矿地质条件,认为在接触带寻找硫化物矽卡岩、硫化物型锡矿有较大前景,而在岩体区具有寻找云英岩型钨矿的潜力.

The Dadongshan tin orefield is complex in terms of mineralization types. The skarn type tin deposits are large in scale and can be divided into tin-bearing skarn subtype and sulfide skarn subtype. Greisen is occurred in outcropped area of granites as dikes or planar greisen. Granites formed during the forth stage of Yanshanian period are the metallogenetic mother intrusion with high content of silicon and alkali metals (SiO_(2)= 74. 96%~75. 28%;Na_(2)O+K_(2)O=7.37%~8.54%;Na_(2)O/K_(2)O<1),showing similar lithochemical features to tungsten-tin mineralized granites in Nanling region. The tin deposits in the orefield can be classified into three genetic types,i. e. contact metasomatictype, magmatic hydrothermal type and weathering type. Analyses of ore-forming geological conditions show that there are relatively excellent prospecting potential of sulfide skarn and sulfide tin deposits along the contact zone and of greisen tungsten deposits in the outcropped area of granites.