Structure and rifting evolution of the northern Newfoundland Basin from Erable multichannel seismic reflection profiles across the southeastern margin of Flemish Cap

J K Welford,J.-C Sibuet,S P Srivastava,S Deemer,J Hall,J A Smith

doi:10.1111/j.1365-246x.2009.04477.x

Abstract

We present the results from processing and interpreting five lines from the 1992 Erable multichannel seismic reflection experiment extending from the southeastern margin of Flemish Cap into the northern Newfoundland Basin. These profiles reveal significant along strike variations in the rifting styles experienced by Flemish Cap. In the southwest, a 100-km-wide transition zone is identified between thinned continental crust and thin oceanic crust. Similar to the conjugate Galicia Bank and Iberian margins, this transition zone contains a section of deep basement adjacent to a series of shallower ridges and is interpreted as exhumed serpentinized mantle. Along strike towards the northeast, this transition zone pinches out completely within 100 km and is replaced by thin oceanic crust directly adjacent to thinned continental crust. By interpreting nearby seismic profiles and profiles on the conjugate margins using the same classification criteria, we construct regional maps of the distribution of crustal domains on both sides of the North Atlantic. These maps reveal significant variations in rifting style on the conjugate margins and along strike of each margin and also highlight the role of ancient transfer zones in compartmentalizing these rifting variations into four distinct regions. We propose that the limited localization of shallow topographically high serpentinized peridotite ridges on the Newfoundland-Iberia and Flemish Cap-Galicia Bank conjugate margins, was directly related to an increase in the rate of extension following the separation of Flemish Cap and Galicia Bank which exhumed deeper, less serpentinized mantle.

Highlights

The non-volcanic/magma-poor Newfoundland/Iberia and Flemish Cap/Galicia Bank conjugate continental margins (Fig. 1) are ideal locations for studying the dynamics of rifting since most of their extensional crustal structures have not been altered or obscured by magmatic processes
While early attention was focused on central Iberia and Galicia Bank, seismic data coverage over the Newfoundland and Flemish Cap margins has increased to the point that better comparisons and interpretations are possible for the conjugate pair
Into the northern Newfoundland Basin allows us to obtain valuable geometrical constraints on rifting. By comparing these constraints with those obtained along strike and on the Iberian and Galicia Bank margins, we investigate regional variations in rifting style and speculate about the timing of rifting, rifting processes and the influence of features like transfer zones on how these specific conjugate margins evolved

Summary

Introduction

The non-volcanic/magma-poor Newfoundland/Iberia and Flemish Cap/Galicia Bank conjugate continental margins (Fig. 1) are ideal locations for studying the dynamics of rifting since most of their extensional crustal structures have not been altered or obscured by magmatic processes These margins have been the focus of significant geophysical investigation (Boillot et al 1980, 1987; Shipboard Scientific Party 1987; Keen & de Voogd 1988; Mauffret et al 1989; Todd & Reid 1989; Tucholke et al 1989; Whitmarsh et al 1990; Pinheiro et al 1992; Beslier et al 1993; Whitmarsh et al 1993; Reid 1994; Sibuet et al 1995; Funck et al 2003; Henning et al 2004; Hopper et al 2004, 2006; Lau et al 2006a,b; Shillington et al 2006; van Avendonk et al 2006; Clark et al 2007; Afilhado et al 2008; Deemer et al 2009). In the Newfoundland Basin, an increasing number of seismic surveys have illuminated the transition zone but with only one drillhole available for ground truthing (Shipboard Scientific Party 2004; Muntener & Manatschal 2006; Tucholke & Sibuet 2007), significant debate remains

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Conclusion