Читать книгу Continental Rifted Margins 2 - Gwenn Peron-Pinvidic - Страница 10

Gaël LYMER1 and Tim J. RESTON2

1 Fault Analysis Group/iCRAG (Irish Centre for Research in Applied Geosciences), School of Earth Sciences, University College Dublin, Ireland

2 School of Geography, Earth and Environmental Science, University of Birmingham, UK

The West Iberian Margin has historically been at the forefront of fundamental research on rifting and breakup. Decades of drilling, sampling and geophysical campaigns, including a recent high-resolution 3D seismic volume, have placed the West Iberian Margin among the best-documented continental margins worldwide. Data from the West Iberian Margin allowed initial development of the concepts of hyper-extension, detachment faulting, “undercrusting” by serpentinites and exhumed mantle rocks. Above all, they have revolutionized our modern scientific concepts of rifting by allowing us to demonstrate that the rifting process is diachronous across margins and involves the migration and/or the focusing of extension towards the future oceanic spreading center during rift evolution. These concepts resulted in the early theories about the processes of oceanic basin development and still contribute to defining the latest models of continental breakup. Three major models of continental breakup have been defined from observations at the West Iberian Margin: depth-dependent stretching (DDS), cross-cutting polyphase faulting and sequential faulting. The fundamental disparities between these models – in terms of the timing of faulting, the number of faulting phases and rheologies – demonstrate that our knowledge of rifting and breakup remains fundamentally incomplete, as long as the timing of geological events at rifted margins remains undefined.

In this chapter, we summarize the historical investigation of the West Iberian Margin and the current geological knowledge on the features formed during their rift evolution and breakup. We present an overview of their structures and litho-stratigraphy, and the latest ideas for their evolution, highlighting the key remaining questions, how they might be addressed and why answering these questions would represent a paradigm shift in our knowledge of the concepts of development of rifted margins worldwide.