The crustal structure of Central East Greenland: results from combined land-sea seismic refraction experiments
We present results from the first combined marine-land seismic refraction survey in the area of the East Greenland Caledonides, together with gravimetric measurements. The seismic and gravimetric models show a consistent picture of the crustal structures. In the western area, which is part of the Ca...
| Published in: | Geophysical Journal International |
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| Main Authors: | , |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1998
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| Subjects: | |
| Online Access: | http://gji.oxfordjournals.org/cgi/content/short/135/1/63 https://doi.org/10.1046/j.1365-246X.1998.00586.x |
| Summary: | We present results from the first combined marine-land seismic refraction survey in the area of the East Greenland Caledonides, together with gravimetric measurements. The seismic and gravimetric models show a consistent picture of the crustal structures. In the western area, which is part of the Caledonian mountains of East Greenland, crystalline rocks with P -wave velocities of about 5.5 km s− 1 occur at the surface. Seismic velocities increase continuously with depth and reach values of 6.6 km s− 1 at 12 km. The total thickness of the crust as revealed by the seismic measurements reaches high values of up to 48 km in the southwestern part of the region (28° W). Gravity data, which also cover the region west of the seismic lines, indicate a possible further increase of the crustal thickness. These high values raise questions about whether they represent a Caledonide crustal root, which would stand in strong contrast to the findings in the Caledonian areas of Europe, or whether the crustal thickening represents a pre-Caledonian structure and is affine rather to the older regions west of the Caledonides and adjacent to the Greenland inland ice. Towards the east crustal thickness decreases rapidly. It reaches a minimum of 22 km under the Late Palaeozoic-Mesozoic sedimentary basin of Jameson Land. The crustal thinning is the result of the stretching of East Greenland, which was produced by a general extensional tectonic regime and the collapse of the Caledonian mountain chain from Devonian time onwards. In the area of transition from thick to thin crust, the seismic data indicate a layered structure at the Moho. This region is interpreted as a zone of extensive intrusion or underplating during the rifting in the Tertiary. |
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