Magnetic characterization of the zigzag shaped J‐anomaly: Implications for kinematics and breakup processes at the Iberia–Newfoundland margins

Abstract

Lithospheric breakup is generally defined as the process that results in a new plate boundary and oceanic crust. However, how this process occurs in magma‐poor systems remains debated. As recently suggested, the J‐magnetic anomaly at the Iberia–Newfoundland margins has polygenic sources and therefore cannot be interpreted as an isochron. However, the presence of the J‐anomaly on both margins suggests a common origin. By using analytic signal map of magnetic data, we highlight landward zigzagged limits for the J‐anomalies at the Iberian–Newfoundland margins. The zigzag segments neither match the axis nor the transform systems of previously proposed plate reconstructions, but are aligned with NE‐SW Palaeozoic trends. However, they can be fitted using recently published plate restorations, as expected if they have a single origin. Therefore, a link between the location of syn‐ to post‐breakup magmatic additions along the J‐anomaly and an inherited lithospheric trend is proposed.

A kinematic reconstruction of Iberia using intracontinental strike‐slip corridors

“…In the southern N‐Atlantic, the progressive northward oceanization is compatible with the model of Szameitat et al. (2020) involving a V‐shape propagator.…”

“…The V‐shaped propagation of these magnetic anomalies could result from lateral contrast of magnetization between different types of crust, as described by Szameitat et al. (2020) for the M‐series in the southern N‐Atlantic (Figure 4b,c).…”

“…During a large part of its Mesozoic history, Iberia was a continental rigid block delimited by intracontinental deforming regions, 40–200 km wide (Ady & Whittaker, 2019; Angrand et al., 2020; King et al., 2020) and hereafter referred to as strike‐slip corridors. The M‐series magnetic anomalies fringing Iberia on its N‐Atlantic side have been shown to not represent classical oceanic magnetic anomalies and therefore to be unreliable for reconstructions (Nirrengarten et al., 2017; Szameitat et al., 2020). Moreover, kinematic reconstructions proposed Late Cretaceous subduction east of Iberia not harmonizing with tomographic data in the Pyrenees (Chevrot et al, 2018; Gong et al., 2008; Neres et al., 2012; Nirrengarten et al., 2017; Vissers & Meijer, 2012b).…”

The continent-to-ocean transition in the Iberia Abyssal Plain

“…The J anomaly may extend into the West Iberia Margin (Tucholke and Ludwig, 1982;Russell and Whitmarsh, 2003), but it has been argued that it was not formed by seafloor spreading and is not an isochron, and thus should not be used for kinematic reconstructions (Nirrengarten et al, 2017(Nirrengarten et al, , 2018. Based on magnetic field modeling, the J anomaly has been associated with a basement ridge of thick crust formed by synrift magmatic underplating and extrusive volcanism on preexisting exhumed mantle (Bronner et al, 2011;Szameitat et al, 2020). In contrast, the FRAME-p3 model shows that the J anomaly actually occurs over subdued basement relief (Figs.…”

Investigating the Plate Kinematics of the Bay of Biscay Using Deformable Plate Tectonic Models

“…The three main plate kinematic scenarios proposed for Iberia during the Early-Mid Cretaceous consist of a strike-slip and rift-perpendicular scenario along the Iberia-Eurasia plate boundary (Jammes et al, 2009), a strike-slip scenario (Olivet, 1996;Stampfli & Borel, 2002), and a scissor scenario implying subduction within the Pyrenean realm (Sibuet et al, 2004;Vissers & Meijer, 2012). The origins of these three contrasting plate kinematic scenarios arise from geological observations in the Pyrenees, the integration of the southern North Atlantic and Alpine-Tethys plate kinematics, discrepancies with paleomagnetic data, and the uncertain nature of offshore M-series magnetic anomalies and their inappropriate use as plate kinematic indicators prior to M0 (Angrand et al, 2020;Barnett-Moore et al, 2016;Causer et al, 2019;Nirrengarten et al, 2017Nirrengarten et al, , 2018Szameitat et al, 2020;van Hinsbergen et al, 2020).…”