中文摘要：

在北苏鲁超高压变质带的威海地区,普遍发育与含黑云母正片麻岩深熔作用存在密切成因关系的伟晶岩,它们主要以规模不一的脉体、无根不规则的透镜体赋存于超高压的含黑云母正片麻岩中。锆石中矿物包体的激光拉曼鉴定、锆石阴极发光图像分析、不同性质锆石微区U-Pb定年以及锆石原位微量元素和Lu-Hf同位素测试等综合研究结果表明,伟晶岩（WH19）中的锆石成因相对复杂,可划分为两种类型：第一类具有强发光效应（白色）的继承性岩浆结晶锆石的核（Ic）、强发光效应（灰白色）新生岩浆结晶锆石的幔（m）和相对弱发光效应（黑色）的岩浆结晶锆石的边（r）;第二类具有强发光效应（灰白色）新生岩浆结晶锆石的核（c）和相对弱发光效应（黑色）的岩浆结晶锆石的边（r）。其中继承性岩浆结晶锆石核部（Ic）的矿物包体为Qtz＋Kfs＋Pl＋Ap,与围岩含黑云母正片麻岩的基质矿物组合十分相似。继承性岩浆结晶锆石核部（Ic）记录的206Pb/238U年龄为769～228Ma,所组成的不一致线的上交点年龄为788±21Ma,下交点年龄为225±20Ma,这两组年龄分别与围岩含黑云母正片麻岩的原岩形成时代和超高压变质时代完全一致,表明该类继承性岩浆锆石来源于围岩含黑云母正片麻岩。新生岩浆结晶锆石的核部（c）和幔部（m）的矿物包体为Qtz＋Kfs＋Ap,与伟晶岩的基质矿物组合相似,记录的206Pb/238U年龄为223～217Ma,谐和年龄为219.5±1.4Ma,应代表伟晶质岩浆的形成年龄或新生岩浆的初始结晶年龄。这组年龄比含黑云母正片麻岩的超高压年龄偏新,表明深熔作用应滞后于苏鲁地体超高压变质时代,更有可能发生于构造折返麻粒岩相升温减压退变质阶段。新生岩浆结晶锆石的边部（r）矿物包体相对较少,记录的^206Pb/^238U年龄为217～211Ma,谐和年龄为214.6±1.7Ma,应代表伟晶质岩浆结

英文摘要：

Migmatites, such as pegmatite and granitic leucosome are widely distributed within biotite-bearing orthogneiss in the Weihai area, north Sulu ultrahigh-pressure （UHP） metamorphic terrane, eastern China. A combined study of mineral inclusions, cathodoluminescence （CL） images, U-Pb SHRIMP dates, and in-situ trace element and Lu-Hf isotope data for zircons provided insight into the nature and timing of partial melting in these rocks. Most magmatic zircons in the studied pegmatite sample WH19 have distinct overgrowths around inherited magmatic cores （type I） or occur as new, simple crystals without inherited magmatie cores （type Ⅱ）. Inherited magmatic core with Qtz ＋ Kfs ＋ Pl ＋ Ap inclusions, record ^206Pb/ ^238U ages ranging from ^769 to ^228 Ma, which show a upper intercept at 788±20 Ma and a lower intercept at 228±20 Ma, representing a Neoproterozoic protolith age and a UHP metamorphic age of biotite-bearing orthogneiss as a host rock, respectively. In contrast, newly formed magmatic zircon core and mantle with Qtz ＋ Kfs ＋ Ap inclusions that record partial melting time of 219. 5 ± 1. 4 Ma shortly after UHP metamorphic age, whereas the magmatic rims record a younger （214.6 ± 1.7 Ma） Late Triassic regional amphibolite-facies overprint. These data indicate that the partial melting in the north Sulu UHP terrane took place in the UHP biotite-bearing orthogneiss, but that occurred during post-UHP, retrograde granulite-facies metamorphism. Furthermore, crystallization of the magmatic zircon associated with the partial melting was complete by the time of the regional amphibolite-facies retrograde stage. Inherited magmatic zircon cores from pegmatite sample WH19 give disperse ^176Lu/^177Hf （0. 00031-0. 00360） and ^176 Hf/^177 Hf（t） （0. 282051-0. 282348） with εHf（t） ratios of --8.3-2.1 and Hf model ages （TDM2） Of 1. 43 -2. 02 Ga, indicating the protolith of the biotite-bearing orthogneiss as the host rock was generated by reworking of Paleoproterozoic crust. In co