辽东-鲁西中-新太古代高钾花岗质岩石成因及壳幔动力学体制

A great transformation of global geodynamic regimes of crust/mantle interactions that occurred at ~3.0 Ga has been indicated by a mass of recent studies, and the high-K granitoid appearing is the most crucial signature of the great transformation. As the investigated object for 2.9-3.1 Ga and 2.60-2.47 Ga high-K granitoids in Eastern Liaoning Anshan-Benxi and Western Shandong terranes, respectively, of the North China Craton, this program plan to study features and types, spatial and temporal distribution, and petrogenesis of lithological assemblages of the earliest high-K granitoids after the great transformation and the high-K granitoids at the end of Archean through tracer methods of zircon U-Pb-Lu-Hf-O and whole-rock Sr-Nd-felspar Pb isotopic and trace elementary systematics. Combining petrogenesis of gabbros, high-Mg diorites, quartz mozonites and sanukites that show close relationships with these high-K granitoids, this study want to analyze times and features and natures of ancient continental, juvenile crustal or crust-mantle hybrid sources of these high-K granitoids,and crust/mantle interaction processes. On the basis of investigations on the petrogenesis of these high-K granitoids and correlated igneous rocks, we want to explore the appearing reasons of the Meso- to Neoarchean high-K granitoids, responses of the NCC to the global Meso- to Neoarchean great tranformation event and its crust/mantle dynamic mechanism, to innovate and develop the theory and cognition on formation and evolution of the early continental crust of the earth.

近年来大量研究表明~3.0Ga全球壳幔动力学体制发生了明显转折,主要标志之一是高钾花岗质岩石的出现。本项目拟以辽宁鞍山-本溪2.9-3.1Ga和鲁西2.60-2.47Ga高钾花岗质岩石组合为对象，通过锆石U-Pb-Lu-Hf-O、全岩Sr-Nd-长石Pb同位素和微量元素示踪，开展这一转折期后最早出现的和太古代末期高钾花岗质岩石组合特征、类型、时空分布和岩石成因研究，结合与之有密切成因联系的辉长岩、高镁闪长岩、石英二长岩、赞岐岩等岩石成因研究，分析不同阶段高钾花岗质岩石组合所记录的古老陆壳、初生地壳性质与特征和太古宙不同阶段的壳幔岩浆作用过程，分析中太古代晚期高钾花岗质岩石组合出现的原因、华北克拉通对全球中太古代晚期全球壳幔动力学体制转化事件的响应，探索中-新太古代华北克拉通中-新太古代壳幔动力学机制，创新和发展早期大陆地壳形成演化理论和认识。

国家自然科学基金项目《辽东-鲁西中-新太古代高钾花岗质岩石成因及壳幔动力学体制》（41772188）重点研究了华北克拉通东部辽东和鲁西地区太古宙高钾花岗质岩石和相关火成岩的岩石成因、变形特征及形成的构造背景。本项目获得了如下创新成果：（1）中太古代晚期世界上最早、规模最大的鞍山-本溪高钾花岗质岩石组合的岩浆起源于既有古老变质火山、也有变质沉积物和变质花岗质岩石的混合源区，标志地表物质明显卷入到下地壳，形成于前板块俯冲的Buckling构造过程。（2）新太古代晚期赞岐岩类高钾花岗岩组合，其岩浆主要起源于受俯冲沉积物熔体、板片熔体和脱水流体交代的岩石圈地幔的部分熔融，形成于典型岛弧构造背景。（3）在新太古代晚期-末期广泛出现的壳源高钾花岗质岩浆作用，可以形成于高温Buckling构造对接带、弧-陆和弧-弧碰撞带等以碰撞-对接为主体的构造背景，也可以出现面型分布以地壳减薄为主体的克拉通化过程。（4）创立了太古代地壳厚度和热状态的研究方法，确定了华北克拉通东部从~2.9-2.5 Ga的莫霍面的深度和地幔潜能温度，重建了大陆岩石圈的热结构，揭示板块构造已经全面启动。（5）中太古代晚期以高热前俯冲对接构造体制为主和新太古代以热的板片俯冲形成的侧向增生动力学体制为主。（6）本项目共发表学术论文25篇，其中第一标注论文8篇（外刊发表的SCI论文7篇，1篇论文发表在Nature Communications刊物上），第二标注论文16篇（外刊发表的SCI论文14篇），所发表的文章已被引用293次。（7）本项目共培养博士研究生5人。