中国东北是认识和理解大洋俯冲带弧后地区深部动力学过程、陆内火山成因的理想场所。虽然前人研究表明太平洋俯冲板片正滞留于该地区下方地幔过渡带中并可能发生脱水作用，但对上地幔的实际含水量分布以及相关交代、岩浆作用仍不清楚。由于地幔矿物电导率对含水量变化非常敏感，利用天然源电磁感应方法探测上地幔电导率分布将有助于厘清上述问题。然而，受到场源信号周期范围的制约，传统深部电磁测深方法难以有效约束上地幔深度的电导率结构。本研究拟基于东北地区已有相对密集的长期电磁观测剖面资料，利用对上地幔导电性敏感的太阳静日变化（Sq）电磁响应构建上地幔的精细电导率结构，并通过结合高温高压实验等多学科资料定量约束含水量的空间分布。本研究有望为上地幔的实际含水状况提供关键观测依据，同时对理解东北地区新生代构造、岩浆（火山）、成矿作用的深部动力学机制具有一定的指导意义。

Northeast China is an ideal location to recognize and understand the deep geodynamic processes of back-arc regions and the origin of intraplate volcanism. Although previous studies in this area have suggested that the westward subducting Pacific slab is currently stagnant in the mantle transition zone and may introduce water into the overlying upper mantle through dehydration, the actual water distribution in the upper mantle and the subduction-related metasomatic and magmatic processes remain largely unclear. Given that water can significantly enhance electrical conductivity, mantle conductivity structure obtained from natural-source electromagnetic soundings can help to clarify these issues. However, owing to the limited period range of the source signals, traditional electromagnetic sounding methods are unable to effectively constrain the conductivity structure in the upper mantle depths. In this study, based on the newly obtained long-term electromagnetic data from a relative dense profile in NE China, we plan to rebuilt detailed upper mantle conductivity structure by using solar quiet (Sq) daily variations, which are mainly originated from the ionospheric current systems and particularly sensitive to conductivity distribution in the upper mantle depths. Combining information from other related multi-disciplinary studies, we will further determine the spatial distribution of water in the upper mantle. These results could provide evidence for the water content distribution in the upper mantle, and improve our understanding of the deep geodynamics of the Cenozoic tectonic, magmatic (volcanic) and metallization events in Northeast China.