In this study we investigate how landscapes are inherited from
continental rifting on long timescales. Areas that are currently
undergoing extension typically have topographical features and drainage
patterns that are easy to recognize. How these topographical rift
features evolve on long timescales, however, is poorly understood.
Recent work from onshore parts of the northeast Atlantic margin suggests
that some present-day landforms are inherited from late Paleozoic,
Mesozoic and Early Cenozoic rifting and opening of the North Atlantic
Ocean. These relict landscapes are difficult to recognize, as the
topography is reworked by post-rift Cenozoic uplift and erosion, as well
as repeated Quaternary glaciations. For that reason, interpretations of
these landscapes vary considerably. However, some of these relict rift
features are demonstrably preserved in half-grabens, as sedimentary
basins with well-established ages. Our research studies the topography
around three half-grabens in Norway and on Svalbard, and aims to
quantify landscape inheritance from rifting and margin formation. To do
so, we use structural and geomorphological field observations, and
remote sensing such as digital elevation model analyses and seismic
images. We classify landscapes in detail, systematically reviewing
present-day landscape distributions in order to distinguish extensional
tectonic landforms from other geomorphological features. Preliminary
results find that certain present-day landforms along the northeast
Atlantic Ocean are relics from rifting from as far back as the late
Paleozoic. This is expressed by, among other things, major topographic
contrasts between footwall and hanging wall in all three half-grabens.
This means higher topographical elevations and deeper incision in the
footwalls compared to the hanging walls. Additionally, the three study
areas have very different landscapes, suggesting that their individual
post-rift landscape evolutions were very different from each other.
These differences seem to be influenced by the degree of glacial
incision, the degree of erosional exploitation of pre-rift structures,
and possible Late-Cretaceous or younger reactivation of basin-bounding
normal faults.