Garnet becomes an important tool to analyze the timing and genesis of metamorphic rocks (especially skarn deposits), clastic sediments, and igneous rocks due to its common occurrence. However, for in-situ U-Pb dating of garnet, is there any difference to use 91500 or Willsboro as a primary standard and can a robust age be obtained for low-U (≤ 10 ppm) garnet as Willsboro and Mali in small spot sizes of 32–16 μm? Can garnet U-Pb dating be used to exactly identify the ore-related intrusive unit in an intrusive complex and its related distal skarn system setting? In this contribution, Willsboro, Mali, QC04, and three other andradite samples WMQ-2(3), WSG-1, and YJ-4(2) from the Anji polymetallic skarn deposit were analyzed to discuss these questions. In our analysis, zircon 91500 is confirmed as reliable reference material for these garnets in spot sizes of 32–16 μm. Notably, both 91500 and Willsboro are suitable as primary standards for the garnets as Mali and QC04, which have extremely low common lead and are mainly plotted at the lower intersection in the Tera-Wasserburg Concordia diagram; Willsboro is not suitable to calibrate the garnets as WMQ-2(3), WSG-1, and YJ-4(2), which contain relatively high common lead and fall along a mixing line between initial common Pb and radiogenic components in the Tera-Wasserburg Concordia diagram. In the Anji polymetallic system, based on garnet U-Pb, mica Ar-Ar and previous zircon U-Pb dating, proximal Pb-Zn-Ag-Cu and distal Fe and Fe-Zn-Cu skarn deposits were formed by the same magmatic-hydrothermal-mineralization event at 137–138 Ma. These ages, geological evidences, our and previous lead isotopic compositions confirm that Fe, Fe-Zn-Cu, Pb-Zn-Ag-Cu, Mo, and fluorite-chalcedony mineralization have genetic relationships with fine-grained granite. Compared with other units of the Wushanguan complex, the lead isotopic compositions indicate that fine-grained granite supplies most ore-forming materials, and the increased mantle-sourced materials may play an important role in the formation of the Anji skarn system.

石榴石由于经常发生，因此成为分析变质岩（尤其是矽卡岩矿床），碎屑沉积物和火成岩时间和成因的重要工具。但是，对于石榴石的原位U-Pb定年法，使用91500或Willsboro作为主要标准品有什么区别，对于低U（≤10 ppm）石榴石，Willsboro和Mali可以在小点获得稳健的年龄尺寸为32–16μm？石榴石U-Pb测年可以用于准确识别侵入复合物中的矿石相关侵入单元及其相关的远景矽卡岩系统设置吗？在这项贡献中，分析了安吉多金属矽卡岩矿床中的Willsboro，Mali，QC04和其他三个辐射样品WMQ-2（3），WSG-1和YJ-4（2）来讨论这些问题。在我们的分析中 锆石91500被确认为这些石榴石的可靠参考材料，光斑尺寸为32–16μm。值得注意的是，91500和Willsboro都适合作为石榴石的主要标准，如​​Mali和QC04，它们的铅含量极低，并且主要绘制在Tera-Wasserburg Concordia图的较低交点处。威尔斯伯勒（Willsboro）不适合用于校准石榴石，因为WMQ-2（3），WSG-1和YJ-4（2）含有较高的普通铅，并沿Tera的初始普通Pb和放射源成分之间的混合线下落。 -Wasserburg Concordia图。在安吉多金属系统中，基于石榴石U-Pb，云母Ar-Ar和先前的锆石U-Pb年代，同一岩浆形成了近端Pb-Zn-Ag-Cu以及远端Fe和Fe-Zn-Cu矽卡岩矿床。水热矿化事件在137–138 Ma。这些时代，地质证据，我们和以前的铅同位素组成证实，Fe，Fe-Zn-Cu，Pb-Zn-Ag-Cu，Mo和萤石-玉髓的矿化与细粒花岗岩具有遗传关系。与巫山关综合体的其他单元相比，铅同位素组成表明，细粒花岗岩是大多数成矿物质的来源，而地幔源物质的增加可能在安吉矽卡岩系统的形成中起重要作用。