蓝田和牧护关岩体位于东秦岭造山带西端,两者以洛南-栾川断裂为界。前者主要岩性为巨斑状二长花岗岩和中细粒二长花岗岩,而后者主要由二长花岗岩、花岗闪长岩和黑云母花岗岩组成。选自两岩体的锆石韵律震荡环带发育,Th/U大于0.1,属于岩浆成因锆石,其SIMS U-Pb年龄分别为147±2 Ma和149±1 Ma,均形成于晚侏罗世。蓝田和牧护关岩体锆石εHf(t)值分别集中于-16.9~-7.2和-9.3~-6.8,二阶段Hf模式年龄集中范围分别为1.7~2.3 Ga和1.6~1.8 Ga,指示它们的岩浆来源可能主要为新生的早-中元古代地壳物质。岩石地球化学进一步指示二者形成经历了古老地壳熔融、围岩混染、岩浆混合和结晶分异等复杂演化过程。综合研究表明,东秦岭地区约150 Ma的岩浆作用代表了该区晚侏罗世-早白垩世岩石圈伸展作用,其动力学背景很可能与晚中生代古太平洋板块向东亚大陆边缘俯冲有关。 The Lantian and Muhuiguan rocks are located at the western end of the East Qinling orogen, both of which are bordered by the Luonan-Luanchuan fault. The main lithology of the former is macular porphyritic monzonitic granite and medium-fine granodiorite, while the latter is mainly composed of monzogranite, granodiorite and biotite granite. The rhythmic zircon zone of zircons from the two rocks developed with a Th / U greater than 0.1 and belonging to the magmatic origin zircon with SIMS U-Pb age of 147 ± 2 Ma and 149 ± 1 Ma, respectively, formed in the Late Jurassic world. The εHf (t) values ​​of zircon from Lantian and Muowu rocks concentrate at -16.9 ~ -7.2 and -9.3 ~ -6.8, respectively. The second-order Hf model ages range from 1.7 to 2.3 Ga and 1.6 to 1.8 Ga, indicating that they Of the magma may be mainly derived from the early Mesozoic crustal material. Petrological geochemistry further indicates that the formation of the two experienced complex evolution processes such as ancient crustal melting, surrounding rock contamination, magma mixing and crystallization differentiation. The comprehensive study shows that the magmatism of about 150 Ma in East Qinling area represents the extension of Late Jurassic to Early Cretaceous lithosphere, and its dynamic background is probably related to the subduction of the Paleozoic Paleo-Pacific plate to East Asia continental margin.