The Jan Mayen Microplate Complex (JMMC) in the NE Atlantic is interpreted to mostly consist of continental fragments with possible interstitial embryonic oceanic crust. A complex Cenozoic rifting history accompanied by extensive extrusive and intrusive volcanism have made the geological characterization of the JMMC challenging especially due to poor seismic imaging beneath the breakup basalt succession. The presence of continental crust in the JMMC is inferred by seismic and magnetic data, but ground truthing evidence have yet to be provided. Here, we present the results from a seafloor sampling campaign undertaken in 2011 on the Southern Jan Mayen Ridge complex. Seabed samples were recovered using a gravity corer and a dredge along a 1000 m high escarpment with a 19° slope. Sampling locations were selected based on the interpretation of seismic profiles that suggest the presence of possible pre-breakup successions outcropping along this steep escarpment. Results include a sequence of samples with age diagnostic palynomorph assemblages ranging from Permian/Triassic to Eocene, and including igneous samples related to the Early Eocene breakup volcanism. Importantly, the samples were retrieved from hard substrate in an erosional gully lacking overburden sediments and have ages arranged in younging upward sequential order, supporting their near in-situ position. The sampling results were integrated into a lithostratigraphic pseudo-well that can be used to constrain the evolution and breakup of the JMMC. Additionally, evidence for active migration of Jurassic sourced hydrocarbons comprise the first indication of a working hydrocarbon system, with important implications for the petroleum prospectivity of the Dreki area. Finally, these results confirm that the Southern Jan Mayen Ridge is indeed a sliver of continental crust.
Bibliographical noteThe authors would like to acknowledge the contribution from the vessel’s crew (captain I. Rasmussen) and operator (Thor Ltd), the two surveyors (K. Høysæth and H.B. Bortne), and two sampling assistants (F. Gausepohl and A.-M. Voelsch). Sverre Planke and Dougal Jerram are partly funded through a Norwegian Research Council Centers of Excellence project (project number 223272, CEED). Adriano Mazzini is funded by the European Research Council under the European Union's Seventh Framework Programme Grant agreement n° 308126 (LUSI LAB project, PI A. Mazzini). TGS and VBPR funded the cruise and allowed the publication of the data and interpretation. Steve Killops from APT refined our interpretation of the biomarker data. The reviewers and the editor are also thanked for their constructive comments. Finally, this article is dedicated to the biostratigrapher Haavard Selnes who sadly passed away in 2015.
- Jan Mayen microplate complex
- NE Atlantic
- Petroleum system
- Seafloor sampling