郯庐断裂带北延段熔体-岩石相互作用：来自橄榄岩捕虏体的启示

切穿岩石圈的大型断裂带是地幔与熔/流体反应强烈的区域，也是深入了解熔体-岩石相互作用对岩石圈地幔改造的理想场所。郯庐断裂带是东亚大陆上规模最大的断裂带，其南段在华北克拉通破坏研究中受到了广泛关注。但对郯庐断裂带北延段岩石圈地幔的组成及其改造过程，特别是对其东、西两支处地幔性质的空间差异和交代特征仍缺乏完整的认识。申请人在郯庐断裂带北延段关键位置的密山和吉林地区新发现了普遍发育反应结构或遭受过明显糜棱岩化的橄榄岩捕虏体，是研究熔体-岩石相互作用的绝佳样品。项目将以此为研究对象，在详细岩相学基础上，开展矿物原位主量、微量和Li同位素，以及全岩主量、强亲铁元素和Re-Os同位素分析，限定断裂带东、西两支处地幔属性的空间变化，探讨大型断裂带岩石圈地幔的岩石成因及其演化过程，深化对大型断裂带背景下熔体-岩石相互作用的认识。研究结果将为深入理解断裂带岩浆作用、成矿作用以及脱气作用等过程提供重要约束。

Trans-lithospheric fault zones represent weak zones in the mantle that are exploited as pathways for melts and fluids, and the mantle lithosphere in such areas typically shows evidence for strong reactions with melt/fluid. Peridotite xenoliths from such zones are therefore ideal samples to constrain the chemical and physical effects of melt-rock interactions, leading to a deeper understanding of the resultant lithosphere modification. The Tan-Lu Fault Zone (TLFZ) is the largest fault zone in the East Asia continent, and its southern segment has received extensive attention in the research on the destruction of the North China Craton. However, the lithospheric mantle composition and its evolution in the northern segment of the TLFZ remain incompletely understood. This is particularly true for the differences in metasomatic features and resultant mantle properties between the eastern and western branches of the TLFZ. The peridotites carried by Cenozoic basalts in the northern segment of the TLFZ generally developed reactive textures or suffered obvious mylonitization, and are therefore excellently suited to study melt-rock interactions. In this project, peridotite xenoliths in Mishan and Jilin areas of the northern segment are selected as the study object. Based on detailed petrography, representative samples will be chosen for in situ analyses of major and trace elements and Li isotopes of minerals, as well as analysis of major element and highly siderophile element (HSE) abundances and Re-Os isotopes of whole rocks, with the aim to explore the petrogenesis and evolution of the lithospheric mantle beneath the major fault zone. Combined with results of previous studies, this study will reveal the differences of metasomatic features and lithospheric mantle properties between different branches of the northern segment of the TLFZ. Ultimately, this will lead to a significantly deepened understanding of melt-rock interactions and their variability in major fault zones, which has implications for magmatism and degassing associated with extension, long-term lithospheric stability, and ore formation.