Breakup volcanism and plate tectonics in the NW Atlantic

Abstract

Passive margins are the locus of tectonic and magmatic processes leading to the formation of highly variable along-strike and conjugate margins structures. Using extensive new seismic, gravity, and magnetic datasets, complemented by seabed samples and field work, we investigate the tectonomagmatic evolution of the northwest (NW) Atlantic where breakup-related igneous rocks were emplaced during several Paleogene events associated with lithospheric stretching, continental breakup, and the formation of new oceanic basins. Interpretational methods include integrated seismic-gravity-magnetic (SGM) interpretation and seismic volcanostratigraphy. In addition, seabed and field samples were collected and analyzed to constrain the basin stratigraphy, hydrocarbon potential, and the geochronology and geochemistry of the volcanic sequences. Offshore, 2D seismic data reveal several Seaward Dipping Reflector (SDR) wedges and escarpments in the Labrador Sea, Davis Strait, and Baffin Bay. Onshore, eastward prograding foreset-bedded hyaloclastite delta deposits and overlying horizontal lava successions outcrop on Nuussuaq. These hyaloclastites and lava successions are world class analogues to the Lava Delta and Landward Flows volcanic seismic facies units identified offshore. Our mapping results document an aerial extent of the Paleogene breakup-related volcanics of 0.3×10 6 km 2 , with an estimated volume of 0.5-0.6×10 6 km 3. Basalt samples recovered by dredging the Upernavik Escarpment have late Paleocene to/early Eocene ages, whereas the sedimentary samples provide an excellent seismic tie with the stratigraphy and the geology in this frontier area. From the integrated SGM interpretation, we identify a rapidly thinning crust and changes in top and intra-basement seismic reflection characteristics in the oceanic domain correlated with transition between different magnetic domains. The mapping results were subsequently integrated in a plate tectonic model. The plate tectonic reconstruction and basalt geochronology suggest that the majority of the volcanism in the NW Atlantic

Segmentation of Rifts Through Structural Inheritance: Creation of the Davis Strait

“…The suture, outlined in green as given by van Gool et al (), in this region is perpendicular to the extension direction generated by the plate motion in the late Paleocene/early Eocene (Matthews et al, ). The model rifting first to the south of the Davis Strait follows the geological history of the region, with Labrador Sea spreading occurring before Baffin Bay spreading in the north (Abdelmalak et al, ; Peace et al, ).…”

“…. The model rifting first to the south of the Davis Strait follows the geological history of the region, with Labrador Sea spreading occurring before Baffin Bay spreading in the north (Abdelmalak et al, 2018;Peace et al, 2017).…”

“…Based on this history, a first‐order characterization of the West Greenland rift system (sometimes referred to as the NW Atlantic; e.g., Abdelmalak et al, ) can be given in four points (later referred to as “the checklist”): Rifting south of Davis Strait in the Labrador Sea produced new oceanic crust. Rifting north of Davis Strait in Baffin Bay produced new oceanic crust. A right‐stepping segmentation geometry (the Davis Strait) was formed to link Labrador Sea with Baffin Bay. Continental crust is preserved in the Davis Strait during rifting. …”

“…Based on this history, a first-order characterization of the West Greenland rift system (sometimes referred to as the NW Atlantic; e.g., Abdelmalak et al, 2018) can be given in four points (later referred to as "the checklist"):…”

Northeast Atlantic breakup volcanism and consequences for Paleogene climate change – MagellanPlus Workshop report

“…Seismic volcanostratigraphy is an interpretive framework that relates particular seismic facies to various volcanic emplacement environments, which has enabled large areas of volcanic margins to be interpreted from remote seismic data (e.g. Abdelmalak et al, 2016Abdelmalak et al, , 2019. This framework, developed through the joint analysis of results from ODP Legs 104 and 152 and large amounts of seismic data, enables seismic data to be used to infer the duration of volcanism, emplacement rate changes, subsidence history, and other aspects of volcanic margin formation that are tied to both the underlying geodynamic drivers of rift volcanism and the impact of that volcanism on the hydrosphere and atmosphere.…”