新疆克拉玛依高硅碱性玄武岩中碳酸盐矿物成因及其对岩石成因的约束

高硅碱性玄武岩地幔源区俯冲再循环沉积碳酸盐的识别对深部碳循环的研究具有重要的意义。克拉玛依侏罗纪地层中发育两种类型的高硅碱性玄武岩：含原生碳酸盐矿物的橄榄玄武岩和不含碳酸盐矿物的玄武岩。本项目以克拉玛依含碳酸盐矿物碱性橄榄玄武岩为研究对象，通过详细的岩石学、矿物化学（EMPA和LA-ICP-MS）研究揭示碳酸盐矿物的成因；利用橄榄石中熔融包裹体恢复玄武岩母岩浆成分，并结合全岩Mg-Zn-C-Sr-Nd同位素以及前人高温高压实验成果，约束高硅碱性橄榄玄武岩中碳的来源，揭示是否有俯冲再循环沉积碳酸盐的参与；通过对比含碳酸盐矿物橄榄玄武岩与同一露头发育的不含碳酸盐矿物玄武岩的地球化学特征，查明两类岩石成因上的区别和联系，探讨俯冲再循环沉积碳酸盐是否为高硅碱性玄武岩形成的必要条件，为阐明高硅碱性玄武岩的岩石成因提供一个典型案例，同时也为全球碳循环的向下部分提供新的信息。

The identification of the subducted recycled carbonate in the mantle source of the high-Si alkali basalts can significantly contribute to the study of the deep carbon recycle. There are two different types of high-Si alkali basalts observed in Karamay Jurassic strata, i.e., siderite/calcite-bearing olivine basalt and carbonate minerals-free basalt. In this program, we will focus on the siderite/calcite-bearing alkali olivine basalt and investigate the genesis of the carbonate minerals (i.e., siderite and calcite) based on the detail petrographic observations and the associated minerals chemistry by EMPA and LA-ICP-MS. Studies on the melt inclusions enclosed by olivine grains in the alkali basalts could give us an opportunity to understand the physical and geochemical information on the parental melts, while the whole-rock Mg-Zn-C-Sr-Nd isotope compositions might throw light on the source of the magmatic carbonate minerals in the Karamay alkali basalts. Based on these results, we will further discuss whether the subducted recycled carbonates were involved into the mantle source of the alkali basalts. Additionally, the co-occurrence of some carbonate mineral-free alkali basalts and the siderite/calcite-bearing olivine basalts in the same outcrops in Karamay provide us a rare but perfect opportunity to reveal the genetic links between these two types of high-Si alkali basalt by comparing their geochemical and isotopic compositions. Based on that, we can unravel whether the subducted recycled carbonates are essential to the formation of alkali basalts. Our studies in this program will not only provide crucial constraints to the petrogenesis of the alkali basalts, but also provide important clues to the research of deep carbon recycling.