Imaging mantle transition zone discontinuities in southwest China from dense array ambient noise interferometry

作者：Jikun Feng,Huajian Yao,Weitao Wang

摘要：Body waves retrieved from ambient noise cross-correlation functions(NCFs) have been reported by more and more recent studies in addition to the dominant recovered surface waves. And one of important applications of these recovered body waves is to investigate the structure of discontinuities within the mantle transition zone(MTZ). In this study, clear body wave phases reflected from the MTZ discontinuities at 410 km and 660 km have been observed on the NCFs in the frequency band of 0.1–0.2 Hz from a dense regional seismic array in southwest China. The original timedomain reflected signals in the NCFs were first converted to the depth-domain NCFs based on a velocity model before they were further stacked spatially within different bins. Then the depth-domain NCFs were stacked to investigate the lateral variations of the MTZ discontinuities, that is, the 410-km and 660-km discontinuities. Our results exhibit a simple and lateral coherent P410 P phase and a much more complicated P660 P phase along two profiles, which are in good agreement with mineralogical prediction and recent receiver function studies in the same area. This interferometric method can provide stable reflected body wave phases mainly in the frequency band 0.1–0.2 Hz due to the secondary microseism noise, which can be potentially used for high-resolution mantle interface imaging. This approach is also a good complement to traditional imaging methods, such as receiver function imaging.

發文機構：Laboratory of Seismology and Physics of Earth’s Interior Mengcheng National Geophysical Observatory Institute of Geophysics

關鍵詞：ambientnoiseINTERFEROMETRYMANTLEtransitionzone410-kmand660-kmDISCONTINUITIESreflectedbodywavesSOUTHWESTChina

分類號： P631.4[天文地球—地質礦產勘探][天文地球—地質學]