西太平洋“地球上最大火山”形成机制的三维地球动力学数值模拟

西太平洋为地球上海底火山最聚集的区域，其中的大塔穆火山被称为“地球上面积最大的单体火山”。本项目探索目前尚未解决的重要科学问题：“在洋中脊三联点和地幔柱的共同作用下，地球上最大火山是怎样形成的？”项目拟聚焦如下核心研究内容：(1) 通过一系列三维地球动力学模拟实验，定量研究洋中脊三联点与深部地幔热点相互作用对大塔穆火山形成的影响；(2) 计算耦合的三维地幔流场速度与温度结构，分别用大塔穆火山区内实际观测的磁异常条带、岩浆地球化学成分等作为约束；(3) 计算熔融岩浆量，用主动源地震与重力得到的地壳厚度和体积估算作为约束；(4) 反演出能解释上述观测的最佳模型参数，揭示大塔穆火山形成最关键的地质控制因素。项目申请人已完成大量的前期观测，所在项目组具有地球动力学数值模拟的长期积累。项目创新点在于首次通过定量数值建模研究大塔穆火山的形成机制，对研究地球岩石圈动力演化的基本规律具有重要意义。

The Western Pacific Ocean has the most underwater volcanoes on Earth, and among them the Tamu Massif is proved to be the Earth's largest single volcano. This proposal seeks to address an important question: "How did the Earth's largest volcano form by the interaction between a ridge-ridge-ridge triple junction and a mantle plume?"We focus on following tasks: 1.set up a three-dimensional geodynamic model to describe the ridge-plume interaction; 2.calculate the coupled mantle flow and temperature structure, and constrain with magnetic anomalies and magmatic geochemistry characteristics; 3.calculate melted magma supply, constrain with crustal thickness and crustal volume estimates from seismic sounding and gravity predictions; 4.test optimal theoretical parameters then complete the numerical modeling to discuss the geological control mechanism of the volcano's formation. The practicability of this proposal is high because the applicant has been involved in prior geophysical and geochemical observations and the working panel has experience in numerical modeling for geodynamics. It is creative to conduct a quantitative analysis of the volcano's formation, which can provide insights to the geodynamic evolution of the lithosphere on Earth.