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大陆深俯冲作用对邻区岩石圈地幔影响的时空范围是大陆动力学研究的核心问题之一,来源于大陆岩石圈地幔的火成岩为探索这一科学问题提供了重要资料.我们对华北陆块东南部朝鲜-辽东半岛以及辽南-吉南地区晚三叠世花岗质-镁铁质火成岩进行了详细的岩石学、同位素年代学和地球化学研究,结果表明它们是由华南与华北陆块俯冲碰撞后伸展过程中多元岩浆混合形成;相对亏损和富集地幔组分的识别标志着晚三叠世期间华北陆块东南部表现为亏损与富集岩石圈地幔共存的属性.鲁西-辽南-吉南地区早白垩世镁铁质火成岩Sr-Nd-Pb-Hf同位素组成表现出与郯庐断裂距离有关的空间变化,结合吉南地区三叠纪变质锆石和新元古代岩浆锆石的发现,推测起源于深俯冲华南陆块部分熔融的熔体改造了靠近郯庐断裂带的鲁西一侧(如方城、费县、上峪)和辽南地区的岩石圈地幔,而起源于华北陆块加厚地壳部分熔融的熔体则主要改造远离郯庐断裂带的鲁西西北部(如济南、金岭)和吉南地区的岩石圈地幔.因此,华南大陆深俯冲作用对邻区华北岩石圈地幔影响的时间为晚三叠世-早白垩世,影响的空间范围约为200 km.
The temporal and spatial extent of continental subduction on the lithospheric mantle in the neighboring area is one of the core issues in continental dynamics research. The igneous rocks originating from the continental lithospheric mantle provide important information for exploring this scientific issue. The detailed petrological, isotopic chronological and geochemical studies of Late Triassic granitic-mafic igneous rocks in North Korea-Liaodong Peninsula and southern Liaoning-South China region show that they are subducted by subduction of the South China and North China terranes The assemblage of multivariate magmas formed after the collision and the identification of relative depletion and enriched mantle components indicates the coexistence of depleted and enriched lithospheric mantle during the Late Triassic in the southeastern part of North China. - The Sr-Nd-Pb-Hf isotopic composition of the Early Cretaceous mafic igneous rocks in the southern part of Ji’nan shows a spatial variation related to the Tan-Lu fault distance. Combined with the discovery of Triassic metamorphic zircons and Neoproterozoic zircons in southern China It is speculated that the partial melting of the melt originating from the deep subduction of the South China Block altered the lithosphere near the Luxi fault (such as Fangcheng, Fei County, Shangyu) and the Liaonan area Mantle, while the melt originating from the thick crust in part of the North China terrain mainly reformed the lithospheric mantle away from the northwestern Luxilu (such as Jinan and Jinling) and the Ji Nan area away from the Tan-Lu fault zone. The time of influence on the lithospheric mantle in the adjacent area in North China is from Late Triassic to Early Cretaceous, and the spatial extent of the influence is about 200 km.