Effective Elastic Thickness of the Eastern Canadian Shield
Abstract
We have determined the effective elastic thickness of the lithosphere, Te, in eastern Canada from the coherence between surface topography and Bouguer gravity anomalies. We used three complementary methods to estimate the power and cross spectra: the standard Fourier transform, the maximum entropy method (MEM) and the wavelet transform. The wavelet transform and the MEM yield better spatial resolution than standard Fourier methods. For MEM and Fourier transform methods, Te is estimated over areas 508 x 508 km. The standard Fourier method is used to control our results. The study shows important variations in elastic thickness in eastern Canada where it ranges between 30 and 100km. In the eastern part of the Superior province, the elastic thickness is large (Te> 80 km). Previous studies have shown that the central and western parts of the Superior also have large values of Te. In Labrador, the Nain province (the Canadian fragment of the North Atlantic craton) also seems to have high Te. This result differs from those of previous studies suggesting lower Te near the edge of the continent. This difference may be because our calculations exclude the transition to the continental margin. Between the New Quebec and the Torngat orogens, the core zone has lower Te (≈ 30 -> 60 km) decreasing toward the Grenville front. Low values of the elastic thickness are also inferred for the Ungava Peninsula south of the Cape Smith Belt. Over the entire Canadian Shield, values of Te show no correlation with heat flow. Also, there is no clear geographic trend relating Te and the distance to the edge of the craton. Changes in elastic thickness are more likely related to varying crustal composition.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.T32B0885B
- Keywords:
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- 1236 Rheology of the lithosphere and mantle (8160);
- 8110 Continental tectonics: general (0905);
- 8159 Rheology: crust and lithosphere;
- 8164 Stresses: crust and lithosphere