Deep controls on intraplate basin inversion - Intraplate Earthquakes - page 258

view, and we refer to the review by Turner and Williams ( 2004 ) and the references quoted
therein.
One of the fundamental problems of geoscience is to link cause and effect on a regional
scale and many million years back in time. What are the causative events that result
in intraplate deformation? The North Atlantic realm and the European continent furnish
excellent present and past examples of the existence and action of intraplate stresses
originating from different sources.
In the past, some 65 Ma ago, the generally north-south convergence of Africa and

Europe during the Late Cretaceous (e.g., Rosenbaum et al ., 2002 ) furnishes an example of
stresses transmitted into the interior of the European plate causing compressional shortening
of sedimentary basins and rifts in the Alpine foreland, and hence their inversion (Ziegler,
1987 , 1990 ) . These relatively mild intraplate continental deformations have in Europe
become known as “basin inversion” and the locations of the main examples are sketched
out in Figure 10.1 . The term “basin inversion” describes the process when an elongate
stretch of a former area of subsidence - a sedimentary basin or a continental rift - reverses
its vertical direction of movement and becomes uplifted and eroded (Ziegler, 1987 ) . The
concept was first considered on a regional scale in the European continent by Voigt ( 1962 ) .
With the work of Ziegler ( 1987 , 1990) the concept was placed in a plate tectonic framework
involving a causal relationship between stress-producing processes at plate boundaries (the
Africa-Europe collision) and stress-induced deformation in the interior of the European
continent.
At the present day, the North Atlantic depth Anomaly (NAA), related to the magmatic
opening of the North Atlantic around 56 Ma (Tegner et al ., 1998 ) and still visible in the
melt anomaly of Iceland and the anomalously shallow North Atlantic Ocean, is a source of
excess lithospheric potential energy and anomalous mantle pressure, which causes stresses
that propagate through the lithosphere into the surrounding continental plates.
In this chapter, keeping in mind our goal to link cause and effect, we start with an
overview of the present-day stress field of the North Atlantic-European realm placed in
the context of the NAA (Section 10.2), something reasonably well known, in order to
make inferences about present-day lithosphere processes that “cause” intraplate stresses
and, possibly, deformation. This is followed by an overview of past (

+

65 Ma) intraplate
deformation in Europe and how it occurred (the “effect”), as expressed by the geological
record and predictive models of “basin inversion” (Section 10.3), and a discussion on how
this might inform us as regards the link between intraplate forces and strain in continents
in general (Section 10.4).

10.2 Present-day intraplate stress in the Europe-North Atlantic area

A range of stress sources contribute to the stress state of the lithosphere. These include
(e.g., Ranalli, 1995 ) slab pull, shear resistance at subduction zones and strike slip faults,
convection drag at the base of the lithosphere, stresses transferred to the interior of plates
from plate boundary processes, horizontal gradients of lithospheric potential energy, and