Crustal structure of Iceland and Greenland from receiver function studies

Abstract

[1] We used data from both permanent and temporary seismic networks on Iceland and Greenland to investigate the crustal thickness by partly reinterpreting earlier data (P receiver functions) and adding S receiver functions to better constrain the results. We obtained good conversions from the Moho and also crustal multiples in both Iceland and Greenland. The central ice covered part of Greenland has an average crustal thickness of 40 km, typical for a craton. At the edges of Greenland the crustal thickness decreases to 30-40 km. On the east coast of Greenland, where the track of the Iceland plume is thought to have affected the lithosphere, the crustal thickness is only 24-26 km. In contrast to previous studies, we find that the crustal thickness in the east and the northwest coastal regions of Iceland is more than 40 km, similar to beneath the active volcanic region. In the southwest region of Iceland and along the mid-ocean ridge, the crustal thickness is only 25 km or less. Also in contrast to earlier receiver function interpretations, which deduced a broad crust-mantle transition zone for Iceland, we find indications for a normal, sharper Moho beneath a number of sites.

Continental crust beneath southeast Iceland

“…The geochemical signatures of the Öraefajökull lavas bear witness to this, and an extension of the JMM beneath Öraefajökull also explains the surprisingly thick crust in southeast Iceland. We calculate a maximum crustal thickness of around 32 km, which fits well with seismic refraction results and receiver function analysis (10,45,46) (Fig. S4).…”

Moho depth of the European Plate from teleseismic receiver functions

“…An average Poisson's ratio σ in the crust and the Moho depth H are estimated in a grid search over the σ−Η space, and the (σ, H) pair which is in the closest agreement with the observed converted and reverberated phases is determined. This method was found to be very sensitive to the average Poisson's ratio in the crust, but it works only for sharp Moho (with large contrast of elastic parameters), when clear Moho conversions and their associated multiples are observed (e.g., Kumar et al 2007). Weak point of this method is the assumption of an average V P velocity in the crust.…”

“…For temporary passive experiments, this is even bigger problem, due to the limited number of events. Usually during 1 year of a campaign, only about few tens of good quality records, with magnitude M≥5.5, are collected Gregersen et al 2006;Wilde-Piórko et al 2008 (2005) and Geissler et al (2008) differ only by about ±1 km; however, in other regions, differences can reach more than ±5 km, as is the case for Greenland (Dahl-Jensen et al 2003;Kumar et al 2007). & In seismic refraction and wide angle reflection method observed PmP waves are weak for weak contrast at the Moho (gradient Moho zone).…”

Moho and basement depth in the NE Atlantic Ocean based on seismic refraction data and receiver functions

“…Of particular concern were the measurements on Iceland, as Schlindwein (2006) pointed out that the P-S converted phases there are only weak, which is why the use of the receiver function technique may be limited. For this reason, the 53 available measurements by Kumar et al (2007) were cross-checked with the seismic refraction data and the seismically controlled gravity inversion of Kaban et al (2002). In this process, 14 receiver functions were rejected, as they were not consistent with the other methods.…”