中文摘要：

伊春桃山花岗岩具有高硅、富碱和低钙、镁、偏铝质-过铝质特点,稀土元素配分模式以轻稀土元素略微富集且缓向右倾斜、重稀土元素较为平坦、具有铕亏损的海鸥型,富集高场强元素（HFS）Zr和Ga,亏损Ba、Sr、Eu等大离子亲石元素,与区域上晚二叠世-早侏罗世的正长-碱长花岗岩具有类似的岩石地球化学特征。花岗岩锆石CL图像表明,锆石具有明显的继承性核和新生的边,核部的稀土微量元素变化较大,而新生的锆石边部稀土微量元素较稳定,说明部分锆石的核部受到了后期热事件的影响,而边部则是溶解后再沉淀的产物,即岩浆结晶作用形成。但无论是核部还是边部,它们的微量元素特征都指示其形成于大陆地壳环境,而非洋壳环境。锆石SHRIMPU-Pb定年结果表明,继承性锆石核具有两组平均年龄,分别为2540±10Ma和2471±12Ma,新生的锆石边部平均年龄为1821±10Ma。结合上述特征,我们认为,桃山花岗岩的源岩年龄为2.54Ga,区域上构造热事件的年龄为2.47Ga,而花岗岩的结晶年龄为1.82Ga,因此,桃山花岗岩所在的地区可能为一前寒武纪的古老微陆块。

英文摘要：

Taoshan granite is characterized by high silica and alkali,low calcium and magnesium,and meta-aluminous nature. The chondrite-normalized rare earth element （REE） pattern shows slight light rare earth elements （LREE） enrichment relative to heavy rare earth element （HREE）,with a gently right-oblique LREE pattern and a relatively flat HREE one,which constitute a seagull-like curve with strong Eu negative anomaly. In primitive mantle-normalized trace element （TE） spider diagram,the granite displays features of enrichment of high-field strength elements （HFS） such as Zr and Ga,and depletion of Ba,Sr and Eu,which are similar to those of Late Permian-Early Jurassic syenogranites and alkali feldspar granites in the Yichun area. Cathodoluminescence （CL） images of zircons from this granite indicate that zircons are mostly composed of inherited cores and crystalline rims. The contents of the REE and TE in the zircon cores are changed greatly,but the overgrowth rim＇s still very constant according to Sensitive High-Resolution Ion Microprobe Mass Spectrometer-Reverse Geometry （SHRIMP-RG） analyses,reflecting some cores were affected by late tectonothermal event and happened in Pb losses while the overgrowth rims were products of dissolution-reprecipitation of inherited cores,implying that they were crystallized from the granite magma. Even though,both the inherited cores and rims were forming in a continental crust not in an oceanic crust. Zircon SHRIMP U-Pb dating on the zircon cores yielded two weighted mean ages of 2540±10 Ma and 2471±12 Ma,respectively,whereas the zircon rim gave a weighted mean age of 1821±10 Ma. Based on CL images and REE and TE characteristics,we propose that the protolith of the Taoshan granite has an age of 2.54Ga,undergoing a tectonothermal event at 2.47Ga and an anatexis event at ~1821 Ma. Therefore,the area where the Taoshan granite occurs is an ancient microcontinent in Precambrian.