Structure of the Lithosphere and Upper Mantle in den Ocean-Continent Transition from SS Precursors

我们建议利用GRSN和Gräfenberg台站记录的大量地震资料，研究具有SS前兆的陆-洋过渡中的岩石圈-地幔过渡带。在西南太平洋地震非常活跃的地区，从阿留申群岛、堪察加半岛和日本俯冲带穿过华北克拉通到青藏高原的走廊中，采样了SS反弹点。走廊经过不同的构造单元，如俯冲带、古大陆盾、褶皱带和高原。我们将沿着走廊研究不同地质单元下的岩石圈和地幔转换，并推断深度的地球动力学过程。我们将为早期提出的大陆和海洋之间的结构差异寻找更高分辨率的证据，直至地幔过渡带。SS前体的高分辨率图像还可以揭示俯冲的海洋岩石圈与地幔过渡的相互作用，并有助于回答关于西北太平洋俯冲带下地幔过渡区内板块停滞的规模和程度的经常争论的问题。我们将尝试利用SS波形数据的短周期内容，利用CMP叠加和偏移技术等方法进行实验，获得高分辨率的岩石圈和上地幔图像，提高上地幔不连续体的横向和深度分辨率，并进一步为研究具有SS前体的岩石圈-软流圈边界等浅层结构创造新的可能性。

We propose to use the large amount of seismic data recorded by the GRSN and Gräfenberg stations to study the lithosphere and mantle transition zone in the continent-ocean transition with SS precursors. SS bounce points from events in the seismically very active region of the southwest Pacific sample a corridor from the Aleutians, Kamchatka and the Japan subduction zone through the North China craton to the Tibetan plateau. The corridor passes different tectonic units such as subduction zones, an old continental shield, a fold belt and a high plateau. We will investigate the lithosphere and the mantle transition beneath different geologic units along the corridor and infer geodynamic processes at depth. We will search for higher resolution evidence for the earlier proposed structural differences between continents and oceans down to the mantle transition zone. High resolution images of SS precursors may also reveal the interaction of the subducted oceanic lithosphere with the mantle transition and serve to answer the often debated question about the scale and extent of the slab stagnation within the mantle transition zone beneath the NW Pacific subduction zone. We will attempt to use the short period content of SS waveform data and experiment with methods like CMP stack and migration techniques to acquire high resolution lithosphere and upper mantle images and to improve the lateral and depth resolution for the upper mantle discontinuities and, further more, to create new possibilities to study the shallower structures such as the lithosphere-asthenosphere boundary with SS precursors.