Previous studies of felsic granulite and pyroxenite xenoliths have confirmed the existence of the Archean lower crust beneath the Fuxin region which experienced magma underplating in the Phanerozoic. U-Pb-Hf-O isotopes of zircons in felsic granulite xenoliths from the Fuxin late Cretaceous basalts in the North China Craton were analyzed to evaluate the role of magma underplating in the modification of the Archean lower crust during the Phanerozoic. The felsic granulites recorded a uniform upper intercept age of 2.5 Ga and a spread of concordant Mesozoic zircons from 177 to 105 Ma, with a peak at 118 Ma. Most Precambrian zircons show discordant U-Pb ages and obvious core-rim structure. The Mesozoic zircons from the granulite xenoliths can be divided into two groups: zircons with an age of >106 and those with an age of ≤106 Ma. Zircons with ages older than 106 Ma are characterized by an unzoned or core-rim structure and enriched Hf-O isotopic compositions, whereas zircons with ages of ≤106 Ma mainly exhibit oscillatory zoning and have depleted Hf-O isotopic compositions. Some >106 Ma zircons with strongly negative ε_Hf(t) values of −40.4 to −24.9 are considered to be age resets of ancient zircons. The relatively higher Hf-O isotopic values for the rest of the >106 Ma zircons indicate that various proportions of underplated magmas with high ε_Hf(t) and δ¹⁸O values contributed to their formation. The underplated magmas may have originated from the lithospheric mantle, metasomatized by melts/fluids from subducted Paleo-Asian and Paleo-Pacific oceanic crusts. The ≤106 Ma zircons probably crystallized in a melt from the depleted mantle. These observations suggest that long-lived magma underplating occurred beneath the Fuxin region during the Mesozoic, and the derivation of underplated magmas changed from an enriched lithospheric mantle to a depleted asthenospheric mantle at ∼106 Ma. Combined with our previous studies, we conclude that magma underplating not only provided heat for remelting, but also added exotic material in the modification of ancient lower crust beneath the Fuxin region during the Mesozoic. Furthermore, continuous modifications of cratonic lower crust by magma underplating weaken its refractory and made it more susceptible to chemical erosion and partial melting, which played an important role in the lower crust destruction of the craton.

前期对长英质麻粒岩和辉石岩捕虏体的研究证实，阜新地区存在太古代下地壳，该地区在显生宙经历了岩浆底侵作用。对华北克拉通阜新晚白垩世玄武岩长英质麻粒岩包体中的锆石U-Pb-Hf-O同位素进行了分析，以评价显生宙岩浆底侵对太古代下地壳改造的作用。长英质麻粒岩记录了 2.5 Ga 的均匀上截距年龄，一致的中生代锆石分布范围为 177 Ma 至 105 Ma，峰值为 118 Ma。大多数前寒武纪锆石显示出不一致的U-Pb年龄和明显的核缘结构。麻粒岩捕虏体中生代的锆石可分为两类：年龄>106 Ma的锆石和年龄≤106 Ma的锆石。年龄大于106 Ma的锆石具有无环带或核缘结构和富Hf-O同位素组成，而年龄≤106 Ma的锆石主要表现出振荡分带和贫Hf-O同位素组成。一些 >106 Ma 的锆石具有强负 ε_Hf (t) 值 -40.4 至 -24.9 被认为是古代锆石的年龄重置。其余 >106 Ma 锆石的 Hf-O 同位素值相对较高，表明不同比例的底板岩浆具有高 ε _Hf (t) 和 δ ¹⁸O值有助于它们的形成。盘底岩浆可能起源于岩石圈地幔，被俯冲的古亚洲和古太平洋洋壳的熔体/流体交代。≤106 Ma 的锆石可能是在贫化地幔的熔体中结晶的。这些观测结果表明，中生代时期，阜新地区下方发生了长期的岩浆底侵作用，并且底侵岩浆的来源在~106 Ma时从富集的岩石圈地幔转变为贫化的软流圈地幔。结合我们前期的研究，我们得出结论，中生代岩浆底侵不仅为重熔提供了热量，而且还为阜新地区古下地壳的改造添加了外来物质。此外，