摘要
垄上锡多金属矿床是湘东锡田锡矿田中的一个大型矿床,矿体赋存在锡田复式花岗岩体与泥盆系中统棋梓桥组的接触带中。笔者以白云母为测试对象,利用40Ar/39Ar同位素定年方法,精确厘定了该矿床的形成时间。结果表明:垄上矿床2个白云母样品的40Ar/39Ar坪年龄分别为(155.6±1.3)Ma、(157.2±1.4)Ma,等时线年龄分别为(155.4±1.7)Ma(MSWD=0.74)、(156.5±1.7)Ma(MSWD=1.4),与该矿田中的荷树下锡多金属矿床的成矿年龄(150Ma)在误差范围内一致,也与锡田复式岩体早期花岗岩侵入时间(151～165Ma)吻合。因此得出以下认识:湘东锡田地区主要锡多金属矿床的成矿年龄为150～160Ma;成矿作用与区内的锡田复式花岗岩体关系密切,它们都是华南燕山早期大规模成岩成矿作用高峰期的产物。
The Longshang tin-polymetallic deposit, located in the Xitian area, eastern Hunan, is a large one of the Xitian tin orefield. Its orebodies occur in the contact zones between the Xintian composite granite and carbonate rocks of the Middle Devonian Qiziqiao Formation. In this study, ^40Ar/^39Ar isotopic dating of muscovite was carried out in order to determine accurately the mineralization age of the deposit. The results show that the ^40Ar/^39Ar plateau ages of two muscovite samples from the deposit are 155.6±1.3 Ma and 157.2±1.4 Ma respectively and their isochron ages are 155.4±1.7 Ma （MSWD=0.74） and 156.5±1.7 Ma （MSWD=1.4） respectively, which agree within the error limits with mineralization age （150 Ma） of the Heshuxia tin-polymetallic deposit reported previously in the same ore field and are also in accordance with the early intrusive stage of the Xitian composite granite （151-165 Ma）. Based on these age data, this paper suggests that the mineralization age of the tin- polymetallic deposit in the Xitian ore field is 150-160 Ma and that their mineralization is closely related to the Xitian composite granite. Both are products during a peak stage of large-scale rock- and ore-forming processes in the early Yanshanian in South China.
出处
《中国地质》
CAS
CSCD
2008年第4期706-713,共8页
Geology in China
基金
中国地质调查局地质大调查项目(1212010533307
1212010813061)资助
