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中文摘要：
南秦岭印支期五龙岩体侵位于中元古代佛坪群变质岩，在岩体南部发育一些暗色包体，它们和寄主黑云母花岗闪长岩界限或截然，或呈过渡关系。通过对五龙岩体的地球化学、锆石LA—ICPMS U—Pb年代学研究结果表明，寄主黑云母花岗闪长岩表现出明显埃达克岩的地球化学特征：强烈亏损重稀土元素Yb（0．33×10^-6～0．96×10^-6）和Y（4．77×10^-6～11．2×10^-6）；富集Sr（643×10^-6～1115×10^-6），Ba（775×10^-6～1386×10^-6）；高Sr／Y（57．8～160）和Y／Yb（11．0～14．3）比值，不发育Eu异常（6Eu=0．70～0．83），表明其源区是以石榴石士角闪石为主，很少或没有斜长石。暗色包体表现出高Mg（4．15％～8．13％），Cr（14．8×10^-6～371×10^-6），Ni（20．0×10^-6～224×10^-6）和Nb／Ta（15．4～21．9），暗示其起源于地幔底侵岩浆。锆石LA—ICP-MS U—Pb定年年龄为：225．3Ma±6Ma，应为五龙黑云母花岗闪长岩的侵位年龄。综合分析五龙埃达克质黑云母花岗闪长岩可能是由于幔源岩浆底侵于壳幔边界，诱发增厚的基性下地壳达到含角闪石的榴辉岩相或麻粒岩相发生部分熔融形成埃达克质岩浆，它的形成可能代表了印支期秦岭造山带后碰撞造山阶段勉略洋俯冲板块的断离作用。
英文摘要：
In the south Qinling area, the Wulong pluton intruded in the metamorphic complex of the Fuping Group during Meso-Proterozoic. Some mafic enclaves with clear or obscure contact boundary with the host granodiorites occurred in the southern part of the pluton. Based on the study of petrology, geochemistry and chronology of the granitic rocks, it was indicated that the Wulong pluton was of some adakitic affinities characterized by depletion in HREE （ωyb= 0. 33×10^-6-0.96×10^-6,ωY= 4.77×10^-6-11.2×10^-6）; enrichment in Sr （643×10^-6-1115×10^-6）, Ba （775×10^-6-1 386×10^-6）, high Sr/Y ration （57.3-160） and Y/Yb ration （11.0- 14.3）, slightly negative Eu anomalies（δEu=0.70-0.83）, suggesting a source of major garnet ＋ amphibole assemblage with minor or without plagioclase. The high Mg （ωMgO = 4. 15%- 8.13%）,Cr （14.8×10^-6-371×10^-6）,Ni （20.0×10^-6-224×10^-6）, and Nb/Ta ration （15.42 -21.9） of the mafic enclaves reflected that the pluton was resulted from the mafic mantle magma. The Zircon LA-ICP-MS dating for the Wulong pluton yielded a value of 225.3 Ma± 6 Ma which represented the age of emplacement of the host rocks. Bases on this study,combined with previous work, it was considered that the partial melting of thickened lower crust which was triggered by the under-plating mantle-derived magmas generated the magma. Its formation was probably to represent the break-off of oceanic slab during the late Indo-China orogenic stage in Qinling area.
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