辽宁岫岩县桑皮峪透闪石玉成矿年龄研究

运用偏光显微镜、电子探针对辽宁岫岩县桑皮峪透闪石玉的岩石学特征进行了研究，并运用二次离子质谱仪测定从桑皮峪透闪石玉中分离的锆石和榍石的年龄。结果表明：桑皮峪透闪石玉主要由透闪石组成，次要矿物包括磷灰石、方解石、绿泥石、石墨、褐铁矿、锆石、榍石等。偏光显微镜下桑皮峪透闪石玉的主要结构是毛毡状纤维交织结构、显微细晶质结构和纤维变晶结构；主要构造为块状构造。主要化学成分为SiO₂、MgO和CaO，Mg²⁺/（Mg²⁺+Fe²⁺）值为0.964~0.971。桑皮峪透闪石玉的锆石U-Pb谐和年龄为1 851±7 Ma，榍石的²⁰⁷Pb/²⁰⁶Pb年龄为1 848±17 Ma，表明桑皮峪透闪石玉矿形成于古元古代白云岩的区域变质时期。

A study of the mineralization age of nephrite from Sangpiyu, Xiuyan County, Liaoning Province

The petrological characteristics of Sangpiyu tremolite jade from Xiuyan County of Liaoning Province were studied using polarizing microscope and electron probe microanalysis (EPMA). The zircon and titanite grains which are separated from Sangpiyu tremolite jade were dated by secondary ion mass spectrometry (SIMS). The results show that Sangpiyu tremolite jade is mainly composed of tremolite, and its secondary minerals mainly include apatite, calcite, chlorite, graphite, limonite, zircon and titanite. Under polarized light microscope, the main textures of Sangpiyu tremolite jade are felt-like fiber interweaving texture, micro-fine crystalline texture and fibrous metamorphic texture. The main structure is massive structure. The main chemical components of Sangpiyu tremolite jade are SiO₂, MgO and CaO. The ratio of Mg²⁺/(Mg²⁺+Fe²⁺) ranges from 0.964 to 0.971. The zircon ²⁰⁶Pb/²³⁸U age of Sangpiyu tremolite jade is 1 851±7 Ma, and the titanite²⁰⁷Pb/²⁰⁶Pb age is 1 848±17 Ma. The Sangpiyu tremolite jade was formed in the dolomite during the period of palao-Proterozoic regional metamorphism.