Quantification and Restoration of the Pre‐Drift Extension Across the NE Atlantic Conjugate Margins During the Mid‐Permian‐Early Cenozoic Multi‐Rifting Phases. Issue 1 (3rd January 2023)

• Record Type: Journal Article
• Authors: Abdelmalak, Mansour M.; Gac, Sébastien; Faleide, Jan Inge; Shephard, Grace E.; Tsikalas, Filippos; Polteau, Stéphane; Zastrozhnov, Dmitry; Torsvik, Trond H.
• Is Part Of: Tectonics. Volume 42:Issue 1(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-03
• Subjects: quantification -- pre‐drift extension -- conjugate margin restoration -- NE Atlantic -- crustal structure -- basin modeling; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1029/2022TC007386
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: The formation of the NE Atlantic conjugate margins is the result of multiple rifting phases spanning from the Late Paleozoic and culminating in the early Eocene when breakup was accompanied with intense magmatic activity. The pre‐breakup configuration of the NE Atlantic continental margins is controlled by crustal extension, magmatism, and sub‐lithospheric processes, all of which need to be quantified for the pre‐breakup architecture to be restored. Key parameters that need to be extracted from the analysis of crustal structures and sediment record include stretching factors, timing of rifting phases, and nature of the deep crustal structures. The aim of this study is to quantify the pre‐drift extension of the NE Atlantic conjugate margins using interpreted crustal structure and forward basin modeling. We use a set of eight 2D conjugate crustal transects and corresponding stratigraphic models, constrained from an integrated analysis of 2D and 3D seismic and well data. The geometry and thickness of the present‐day crust is compared to a reference thickness which has experienced limited or no crustal extension since Permian time allowing the quantification of crustal stretching. Based on the eight conjugate crustal transects, the total pre‐drift extension is estimated to range between 181 and 390 km with an average of 270–295 km. These estimates are supported by the results of forward basin modeling, which predict total extension between 173 and 325 km, averaging 264 km. The cumulative pre‐drift extension estimates derived from basin modeling are in turn used to calculate the incremental crustal stretching factors at each of the three main rifting phases between the conjugate Greenland‐Norwegian margins. The mid‐Permian early Triassic rifting phase represents 32% of the total extension, while the equivalent values are 41% for the mid‐Jurassic to mid‐Cretaceous and 27% for the Late Cretaceous‐Paleocene rifting phases. These values are used to establish and present at first, a full‐fit palinspastic plate kinematic model for the NE Atlantic since the mid‐Permian and will be the base for future work on more elaborated models in order to build accurate paleogeographic and tectonic maps. Plain Language Summary: Restoring the effect of the multi‐rifting phases is challenging because it is always difficult to quantify their contribution in the total extension. This is mainly due to the lack of extensive data coverage and trustful stratigraphic interpretation. In our contribution we use an extensive amount of seismic reflection and refraction data covering the NE Atlantic to build a set of eight conjugate crustal transects and their corresponding stratigraphic models. The observed crustal thickness is used to quantify the cumulative pre‐drift extension since the mid‐Permian. Forward basin modeling is used to calculate the incremental crustal stretching factors for each of the main rifting phases. The results are used to establish and present at first, a full‐fit palinspastic plate kinematic model for the NE Atlantic since the mid‐Permian and will be the base for future work on more elaborated models in order to build accurate paleogeographic and tectonic maps. Key Points: We quantify the pre‐drift extension in the NE Atlantic margins using crustal structure data and forward basin modeling We quantify the incremental crustal stretching factors and extension for each of the main rifting phases We restore and establish a full‐fit palinspastic plate kinematic model for the NE Atlantic since the mid‐Permian