The syn‐rift tectono‐stratigraphic record of rifted margins (Part II): A new model to break through the proximal/distal interpretation frontier

Abstract

One fundamental lesson from the last decade's research into rifted margins is that stratigraphic horizons cannot be simply correlated from the proximal into distal domain, which makes the interpretation of poorly calibrated and largely inaccessible distal margins difficult. In this contribution, we propose a new tectono‐stratigraphic model to help break through the proximal/distal interpretation frontier. After reviewing the scientific advances on rifted margins achieved during the last century, we describe the primary spatio‐temporal evolution of active deformation during rifting. We show that different rift domains are associated with specific (1) periods of active deformation; (2) tectonic structures and related stratigraphic architecture; (3) amounts of accommodation creation owing to specific ranges of horizontal widening and vertical deepening and (4) depositional environments. We demonstrate that the sequential localization of extension during rifting results in a younging of the base of passive infill (i.e. sediment deposited in a non‐tectonic setting) oceanward. We propose a panel of few to few tens of My time intervals related to specific tectonic events—our Tectonic Sequences—that may be correlated more or less easily and continuously across rifted margins. This study underlines the value of an iterative approach between fieldwork on fossil rifted margins and offshore geophysical studies, where field studies offer easy‐to‐access and high‐resolution calibration of dismembered rifted margin remnants, while geophysical studies provide comparatively low‐resolution imaging of entire, intact but largely inaccessible, rifted margins. It also highlights the necessity of jettisoning outdated dogma on rifted margins and changing our routines when interpreting seismic sections and outcrops.

Evolution of rift systems and their fault networks in response to surface processes

“…That we see the same phase and domain progression in all models in this study regardless of the rift type (e.g., symmetric, asymmetric, or wide) and efficiency of surface processes supports the application of deformation domains to the margins of a variety of rift configurations (e.g., Chenin et al, 2021). Additionally, that processes like rift obliquity (Agostini et al, 2009) and sediment supply can extend phases helps explain the large ranges of observed margin domain widths (e.g., 10 to 100 km for the necking domain, Chenin et al, 2017).…”

“…The five phases in this study are comparable to the deformation phases (e.g., stretching phase) linked to domains in margin architecture (Lavier and Manatschal, 2006;Peron-Pinvidic et al, 2013). Rifted margin domains comprise the 1) proximal domain (distributed deformation and coalescence) to the 2) necking domain (fault system growth), 3) hyper-extended domain (fault system decline and basinward localization), 4) domain of lithospheric mantle exhumation (no comparable phase), and 5) oceanic crust domain (continental breakup; Chenin et al, 2021). Figure 10 compares the final architecture of our medium bedrock erodibility models at 30 Myr to the structural domains, where we first define anything outside of the initial border faults as the proximal domain.…”

“…Phase 1 (Distributed deformation and coalescence): Phase 1 is analogous to the early "stretching phase" (Peron-Pinvidic et al, 2013;Naliboff et al, 2017;Chenin et al, 2021). The Trondelag platform in Norway provides a remnant example of this phase (Peron-Pinvidic et al, 2013).…”

Evolution of Rift Systems and Their Fault Networks in Response to Surface Processes

“…Phase 1 (Distributed deformation and coalescence) : Phase 1 is analogous to the early “stretching phase” (Chenin et al., 2021; Naliboff et al., 2017; Peron‐Pinvidic et al., 2013). The Trondelag platform in Norway provides a remnant example of this phase (Peron‐Pinvidic et al., 2013).…”

“…The five phases in this study are comparable to the deformation phases (e.g., stretching phase) linked to domains in margin architecture (Lavier & Manatschal, 2006; Peron‐Pinvidic et al., 2013). Rifted margin domains comprise the (a) proximal domain ( distributed deformation and coalescence ) to the (b) necking domain ( fault system growth ), (c) hyper‐extended domain ( fault system decline and basinward localization ), (d) domain of lithospheric mantle exhumation (no comparable phase), and (e) oceanic crust domain ( continental breakup ; Chenin et al., 2021). Figure 10 compares the final architecture of our medium bedrock erodibility models at 30 Myr to the structural domains, where we first define anything outside of the initial border faults as the proximal domain.…”