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P Wave Tomography Beneath Greenland and Surrounding Regions: 1. Crust and Upper Mantle
Author(s) -
Toyokuni Genti,
Matsuno Takaya,
Zhao Dapeng
Publication year - 2020
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2020jb019837
Subject(s) - geology , lithosphere , crust , plume , seismology , transition zone , mantle (geology) , seismic tomography , mantle plume , geophysics , seismogram , tectonics , meteorology , physics
We study the 3‐D P wave velocity ( Vp ) structure of the crust and upper mantle beneath Greenland and surrounding regions using the latest P wave arrival time data. The Greenland Ice Sheet Monitoring Network (GLISN), initiated in 2009, is an international project for seismic observation in these regions using 34 stations. We use a regional seismic tomography method to simultaneously invert P wave arrival times of local earthquakes and P wave relative traveltime residuals of teleseismic events. These data are extracted from the ISC‐EHB catalog; however, for the teleseismic data, we picked new arrival times from seismograms using a cross‐correlation method. Our tomographic results clearly reveal the Iceland plume, the Jan Mayen plume, and a newly discovered “Svalbard plume,” which merge together in the mantle transition zone. A high‐ Vp body exists beneath the Greenland Sea, which might act as an obstacle against the rising Svalbard plume. Furthermore, our results reveal a remarkable low‐ Vp anomaly elongated in the NW‐SE direction at depths ≤250 km beneath central Greenland, which is connected with the Iceland and Jan Mayen hotspots. Although previous studies have suggested a similar feature, our result is the first to show the low‐ Vp zone existing at all depths in the Greenland lithosphere, and its spatial distribution coincides with a high heat flux region. These characteristics indicate that the low‐ Vp zone reflects residual heat from the Iceland plume when the Greenland lithosphere passed over this plume at ~80–20 Ma. Our results also indicate the possible existence of residual heat from the Jan Mayen plume.