Crustal Thickness of the Greenland Craton From Receiver Function Analysis

About 80% of the Greenland continent is covered by the inland ice, and the avail-ability of geological data is thus restricted to the coastal areas and offshore. Information on the subsurface is only available through indirect measurements. In order to investigate the crust and upper mantle a total 16 broad band seismic stations in addition to the four permanent stations were placed in Greenland. Of these six were on the ice sheet. The stations were maintained for periods between 3 months and several years; currently 9 of the temporary stations deployed between May and August 2000 are still in operation. The aim of the project is to utilise receiver function analysis and surface wave dispersion analysis to gain information on the Greenland continent. Here we present the first results on crustal thickness in Greenland based on receiver function analysis on 15 of the stations. Analysing receiver functions from stations on top of 3 km of ice present complications from the P-S conversion and multiples from the base of the ice. However, by modelling the response we can extract crustal information. The coastal stations have been analysed with the method represented by Zhu and Kanamori (2000). The results show crust up to 50 km thick in the Proterozoic of central Greenland, thinner in Archeaean block to the south, and also thinning to the north still in (presumed) Proterozoic area under the icecover. Along the northeastern coast the crust is thinner, as expected by the presence of riftbasins.