Eocene continental breakup in Baffin Bay

We question the timing of continental breakup and early oceanization in Baffin Bay, North-East Atlantic. North of the Ungava fault zone, the breakup was syn-magmatic and led to the development of conjugate volcanic passive margins (VPMs). We investigated the innermost part of the W-Greenland VPM where a remarkable inner-SDR is fully exposed in the Svartenhuk area. Our new radiometric ages and paleomagnetic data from syn-tectonic basaltic lavas indicate that continental stretching and thinning spanned the C26r to, at least, the C24r period, giving an Eocene lower boundary age for continental breakup in Baffin Bay. These results contradict the proposed flooring of Baffin Bay by a Paleocene oceanic crust older than C24n and also question the accretion of oceanic crust before C22. We confront our results to the dynamics of the northward oceanic-rift propagation across the Ungava transform fault system, and we suggest that plate breakup in Baffin Bay occurred ~8 m.y. later than in N-Labrador Sea as a result of the thermal and mechanical barrier effect induced by the Ungava transform zone. •Coupling of 40Ar/39Ar and unspiked KAr ages with paleomagnetic data•Dating of the West Greenland Volcanic Province in Svartenhuk Halvø•Dating of the syn-magmatic deformation of the West Greenland volcanic margin•Baffin Bay continental breakup is younger than Early Eocene (C24r)