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对大麻坪橄榄辉石岩包体利用LA-ICP-MS和SHRIMP进行的锆石U-Pb同位素年代学研究发现,橄榄辉石岩包体中的锆石年龄极其复杂,包括中太古代(3123?.4Ma)、晚太古代(2541?4Ma)、早元古代(1844?3Ma)、古生代(418~427Ma)和两组中生代年龄(223~244,97~158Ma).中生代锆石具有典型的岩浆成因特征(如内部韵律环带结构和高Th含量),反映该地区存在两次中生代隐性岩浆活动.其中97~158Ma年龄与汉诺坝麻粒岩包体的年龄分布一致,反映麻粒岩相变质作用是由岩浆底侵作用带来的大量热引起的,底侵作用和麻粒岩相变质作用同步发生,两种作用至少从158Ma持续至97Ma.418~427Ma年龄则可能反映了加里东期蒙古板块向华北板块俯冲的影响.1.84,2.54和3.12Ga年龄与华北克拉通的3次重要壳幔演化事件一致.这些年龄表明目前该地区深部地壳仍存在古老下地壳物质.
Zircon U-Pb zircon dating from LA-ICP-MS and SHRIMP on the clippings of the ductile olivine pyroxenite shows that the age of zircons in the olivine pyroxene inclusions is extremely complex, including Meso-Archean (3123 4Ma), Early Proterozoic (1844? 3Ma), Paleozoic (418 ~ 427Ma) and two Mesozoic age groups (223 ~ 244,97 ~ 158Ma). Mesozoic zircons are typical The genetic characteristics of magma (such as internal rhythm and high Th content) indicate that there are two Mesozoic recessive magmatic activities in this area, of which the ages of 97 ~ 158 Ma are consistent with the age distribution of Hannover Bagh granulite inclusions, The facies metamorphism is caused by a large amount of heat caused by the magmatic underplating. The underplating and the granulite facies metamorphism occur synchronously, and the two effects occur at least from 158Ma to 97Ma. The age of 418 to 427Ma may reflect Gary The influence of the Mongolian plate to the subduction of the North China Plate in the Eastern China Period. The ages of 1.84, 2.54 and 3.12 Ga coincide with the three major crust-mantle evolution events of the North China Craton, indicating that there are still ancient lower crustal materials in the deep crust in the area at present.