Continental rifting and postbreakup evolution of Southwest Iberia: Tectono‐stratigraphic record of the first segment of the North Atlantic Ocean

• Main Author: Sousa Lemos Pereira, Ricardo Nuno
• Format: Thesis
• Language: English
• Published: 2013
• Subjects: QE Geology; Newfoundland; North Atlantic
• Online Access: https://orca.cardiff.ac.uk/id/eprint/49558/; https://orca.cardiff.ac.uk/id/eprint/49558/1/Final%20Thesis.pdf; https://orca.cardiff.ac.uk/id/eprint/49558/2/Dissertation%20Publication%20form%20signed.pdf

The Southwest Iberia continental margin, located in the south‐eastern North Atlantic Ocean and in proximity of an oceanic triple junction separating the westernmost Tethys, the Central and North Atlantic Ocean, is part of a world‐class example of a magma‐poor hyper‐extended rifted margin that records the complete rift‐to‐drift evolution, mantle exhumation and subsequent tectonic inversion. Nevertheless, the Southwest Iberian margin remains a poorly investigated province and key uncertainties are yet to be addressed. The current work presents an integrated analysis of the tectono‐stratigraphic rift‐to‐drift evolution of the Southwest Iberian margin and discusses its overall geodynamic implications. The tectono‐stratigraphic analysis of the continental margin reveals that three major extensional pulses controlled the architecture of the discrete tectonic sectors prior to continental breakup. Growth strata within each of these sectors denote persistent tectonic subsidence and demonstrate not only the progressive westwards rift locus migration towards the breakup position, but also conclusive evidence of multiphased rifting. In such a context, the current geometry of the margin is interpreted to have resulted mainly from rifting between the conjugate margins of Iberia‐Newfoundland, but also from the combined continental extension between Nova Scotia and Morocco and the oblique rifting in the westernmost Tethys. The integrated tectono‐stratigraphic analysis carried out herein shows that eight discrete Megasequences can be assigned to major tectonic events and used for modelling burial history of the discrete rift segments, consequently demonstrating that extension was significant not only during the transition to seafloor spreading, but also during the Early to mid‐Jurassic. This analysis additionally reveals that similar depositional architectures can be grouped into meaningful Tectonic System Tracts, namely, the Rift Initiation System Tracts (RIST), the Rift Climax System Tracts (RCST), and the Late Rift System ...