湖南东坡矿田金船塘、红旗岭锡多金属矿床Rb-Sr、Sm-Nd同位素年代学研究

The Rb-Sr and Sm-Nd Geochronology Constraints on the Formation Age of Jinchuantang and Hongqiling Tin-polymetallic Deposits in Dongpo Orefield,Hunan Province

与千里山岩体有密切时空联系的东坡矿田是我国主要钨锡多金属矿产资源基地之一。在前人对千里山复式岩体成岩时代和金船塘与千里山岩体第一期似斑状花岗岩侵入活动有关的成矿作用研究的基础上,笔者选择金船塘及红旗岭矿床含矿石英脉中的石英和金船塘矿床矽卡岩矿石中的单矿物,进行石英流体包裹体Rb-Sr和矽卡岩矿物（包括符山石和石榴石）Sm-Nd同位素年代学研究,得出金船塘及红旗岭矿床石英流体包裹体Rb-Sr等时线年龄分别为133.4±5.9 Ma（MSWD=1.3）和143.1±8.7 Ma（MSWD=47）,金船塘矿床矽卡岩矿物Sm-Nd等时线年龄为141±11 Ma（MSWD=0.27）。同位素年代学研究表明金船塘矿床至少存在164 Ma±、133~141 Ma两期成矿作用,在测定误差范围内,它们分别与千里山岩体第一期似斑状花岗岩（152 Ma）和第二期等粒黑云母花岗岩（136~137Ma）的侵入活动有关,而红旗岭矿床的成矿作用与千里山岩体第二期岩浆侵入活动有关。

Jinchuantang and Hongqiling tin-polymetallic deposit are components of Dongpo orefield which is one of the famous mineral resource bases of China and considered to be closely associated to Qianlishan batholith in metallogeny.The quartz from auriferous quartz veins of Jinchuantang and Hongqiling deposit,and skarn minerals（vesuvianite and garnet） from Jinchuantang deposit are sampled for fluid inclusion Rb-Sr dating of quartz and Sm-Nd dating of skarn minerals.The results shows that Rb-Sr isochron ages for fluid inclusion in quartz from Jinchuantang and Hongqiling deposit are 133.4±5.9 Ma（MSWD=1.3） and 143.1±8.7 Ma（MSWD=47） respectively,the Sm-Nd isochron ages for skarn minerals from Jinchuantang deposit are 141±11 Ma（MSWD=0.27）.According to previous research,mineralization of Jinchuantang tin-polymetallic deposit has a strong affiliation to porphyritic granite（first stage） of Qianlishan batholith.Synthesize the geochronology research of Qianlishan batholith and closely relationship between mineralization of Jinchuantang deposit and porphyritic granite（first stage） of Qianlishan batholith,another stage of mineralization during 133~141 Ma is discovered in Dongpo orefield by isochron dating of fluid inclusion Rb-Sr system of quarts vein in Jinchuantang and Hongqiling deposits and single mineral Sm-Nd system of skarn in Jinchuantang deposits.As a result,two stages of mineralization are existed in Jinchuantang deposit,which related to the porphyritic（~152 Ma） and equigranular（133~141 Ma） granites of Qianlishan batholith respectively within the determination error,and mineralization of Hongqiling deposit is dominately associated to equigranular granites of Qianlishan batholith.