Plate-wide stress relaxation explains European Palaeocene basin inversions

Abstract

During Late Cretaceous and Cenozoic times, many Palaeozoic and Mesozoic rifts and basin structures in the interior of the European continent underwent several phases of inversion (the process of shortening a previously extensional basin). The main phases occurred during the Late Cretaceous and Middle Palaeocene, and have been previously explained by pulses of compression, mainly from the Alpine orogen. Here we show that the main phases differed both in structural style and cause. The Cretaceous phase was characterized by narrow uplift zones, reverse activation of faults, crustal shortening, and the formation of asymmetric marginal troughs. In contrast, the Middle Palaeocene phase was characterized by dome-like uplift of a wider area with only mild fault movements, and formation of more distal and shallow marginal troughs. A simple flexural model explains how domal, secondary inversion follows inevitably from primary, convergence-related inversion on relaxation of the in-plane tectonic stress. The onset of relaxation inversions was plate-wide and simultaneous, and may have been triggered by stress changes caused by elevation of the North Atlantic lithosphere by the Iceland plume or the drop in the north-south convergence rate between Africa and Europe.

The ICE hypothesis stands: How the dogma of late Cenozoic tectonic uplift can no longer be sustained in the light of data and physical laws

“…This overburial estimate furthermore is inconsistent with our detailed and thoroughly tested model of inversion zone evolution (e.g. Hansen et al, 2000;Nielsen and Hansen, 2000;Nielsen et al, 2005Nielsen et al, , 2007 because the wells Aars-1 and Farsø-1 are not located on the inversion ridge but in the associated marginal trough, which experienced increased subsidence and not uplift and erosion during the late Cretaceous inversions.…”

“…We furthermore acknowledge that Alpine tectonism has taken place in the Alps and that ridge push developed in the North Atlantic at the time of break-up. Such processes could have contributed to stress variations causing minor flexural displacements during the Cenozoic along inversion structures in the eastern North Sea (Nielsen et al, 2005. However, a direct coupling of in-plane stress variations and Neogene tectonic uplift in Fennoscandia -including the eastern North Sea area -via the referenced interpretations of Neogene sedimentology and stratigraphy (Chalmers et al (this volume)) are at best irrelevant to the ICE hypothesis because this is a clear over interpretation of data.…”

The evolution of western Scandinavian topography: A review of Neogene uplift versus the ICE (isostasy–climate–erosion) hypothesis

“…A preliminary analysis indicates that the correlation between oxygen isotopes and lithology can be extended further into the Oligocene and the Neogene(e.g. Rasmussen and Dybkjaer, 2005), and that variations in sediment accumulation rates in the North Sea may have mainly climatic rather than tectonic explanations, although inversion and small vertical flexural movements occurred (Nielsen et al, 2005(Nielsen et al, , 2007a; Rasmussen and Dybkjaer, 2005).…”

“…During the Cenozoic the Danish basin was a tectonically quiet trap for sediments from Scandinavia, except for moderate flexural inversion movements Nielsen et al, 2005Nielsen et al, , 2007a, which were instrumental in preserving Cenozoic depocentres in gentle flexures and protected them from Quaternary erosion. It is therefore ideal for establishing a high-resolution proxy record of NW European climate.…”

The KTB apatite fission-track profiles: Building on a firm foundation?

“…Ridge-push forces from seafloor spreading in the incipient north Atlantic and the evolution of the north (NASA-LPDAAC, 2001). ASTER GDEM is a product of METI and NASA; fault information based on GISEurope 1:1.5 M dataset of BRGM (Cassard et al, 2008). Atlantic lithosphere due to the Iceland plume may have combined with the Alpine orogenic stresses to shape the Late Cretaceous stress field (Ziegler et al, 1995;Nielsen et al, 2005). From the Late Turonian, culminating in the Late Cretaceous-Palaeocene, the BM was exhumed following stages of reverse faulting in the latest Turonian and post-Santonian/Campanian (Malkovský, 1987;Ziegler, 1990;Ziegler and Dèzes, 2007).…”