Sedimentary basin structure of the Bohai Bay from teleseismic receiver functions
Wu Yan
Ding Zhifeng
Zhu Lupei
Abstract：We calculated P wave receiver functions using 895 teleseismic events from September 2006 to September 2009 recorded by 70 temporary stations lo-cated in the Bohai Bay basin.We found that it is difficult to identify the P to S converted phases from the Moho discontinuity.The first few seconds after the direct P arrival are mainly controlled by the sedimentary structure response which includes the Ps phase generated by the bottom of the basin and its multi-ple reverberations in the basin.Based on these characteristics,we used the neighborhood algorithm to invert the data and try to find the best basin velocity model that produces the best fit between the theoretical receiver functions and observed ones in the least-squares sense.The results show that there is a series of depressions and uplifts orienting in the NNE direction in the Bohai Bay basin. The sedimentary depth in the Jizhong Depression is about 3--6 km.There are several secondary depressions and uplifts alternating in the NNE or NE direction in the Jizhong depression.The thickest sedimentary layer is located in the east-ern Jizhong depression.The above shows the characteristics of a half rift valley (rift valley)-half horst (horst)structure.The ratio of the P velocity to S veloci-ty in the uplifts is larger than that in the depressions,which may be caused by the lack of the Paleogene stratum in the uplifts.The proximity of geothermal fields to the high vP/vS ratio depressions shows a close relationship between the high temperatures of the stratum and the large vP/vS ratios .The average of S velocity of the sedimentary in the uplift is smaller than that in the depression, and the thicker sedimentary area always has a higher average S velocity.These characteristics show a relationship between thick sedimentary and high average S velocity.It may be because that the thicker sedimentary area has a thicker Pa-leogene stratum and the S velocity of the Paleogene stratum is much higher than that of the Neogene and Quaternary stratums.The sedimentary structure pro-vides a base to determine crustal structure beneath the Bohai Bay basin.
Keywords：receiver functionBohai Bay basinsedimentary structureneigh-borhood algorithm
Publication Date：2014-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：13( 837-849 )