EGU2020-4998
https://doi.org/10.5194/egusphere-egu2020-4998
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Mapping the continent-ocean transition in the Eastern Black Sea Basin

Tim Minshull1, Vanessa Monteleone1, Hector Marin Moreno2, and Donna Shillington3
Tim Minshull et al.
  • 1School of Ocean and Earth Science, University of Southampton, Southampton, UK (tmin@noc.soton.ac.uk)
  • 2National Oceanography Centre, Southampton, UK (hector.marin.moreno@noc.ac.uk)
  • 3School of Earth and Sustainability, Northern Arizona University, Flagstaff, Arizona, USA (donna.shillington@nau.edu)

The transition from continental to oceanic crust at rifted margins is characterised by changes in a variety of parameters including crustal thickness, basement morphology and magnetisation. Rifted margins also vary significantly in the degree of magmatism that is associated with breakup. The Eastern Black Sea Basin formed by backarc extension in late Cretaceous to early Cenozoic times, by the rotation of Shatsky Ridge relative to the Mid Black Sea High. Wide-angle seismic data show that anomalously thick oceanic crust is present in the southeast of the basin, while further to the northwest the crust is thinner in the centre of the basin. This thinner crust has seismic velocities that are anomalously low for oceanic crust, but is significantly magnetised and has a similar basement morphology to the thicker crust to the southeast. We synthesise constraints from wide-angle seismic data, magnetic anomaly data and new long-offset seismic reflection data into an integrated interpretation of the location and nature of the continent-ocean transition within the basin. Northwest to southeast along the axis of the basin, we infer a series of transitions from mildly stretched continental crust at the Mid Black Sea High to hyper-thinned continental crust, then to thin oceanic crust, and finally to anomalously thick oceanic crust. We explore the geodynamic processes that may have led to this configuration.

How to cite: Minshull, T., Monteleone, V., Marin Moreno, H., and Shillington, D.: Mapping the continent-ocean transition in the Eastern Black Sea Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4998, https://doi.org/10.5194/egusphere-egu2020-4998, 2020

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Display material version 1 – uploaded on 01 May 2020
  • CC1: Comment on EGU2020-4998, Chao Lei, 05 May 2020

    Hi Tim, faults also occurred on the oceanic crust. And how to define syn-rifted sediment.

    • AC1: Reply to CC1, Tim Minshull, 05 May 2020

      Yes - fair comment. Perhaps I should just say that there is evidence for the presence of syn-tectonic sediment packages that are older than the adjacent oceanic crust (so overlain by the same flat-lying sediments that are immediately lying on top of oceanic basement elsewhere). Also, in this basin one can distinguish different basement morphologies.

  • CC2: Comment on EGU2020-4998, Lucia Perez-Diaz, 05 May 2020

    Hi Tim (et al)

    Sorry if my question wasnt' clear enough in the chat. Your work to me highlights how COBs have very little use - a lot of work and effort is required reconciling contrasting information obtained by different means. In the end, you might "identify" a COB, but it is so uncertain (and I'm not jsut talking about locational uncertainty,  but also the age assigned to it, for example) that if these features are used as the basis on which to lead a plate reconstruction effort, the resulting reconstructions will also be tremendously uncertain. 

    In a paper I co-authored in 2015 we discuss this (), and when I saw your display I thought it really highlighted some of the issues we talk about. I guess my question really was, despite all of this, do you still think there is a value in using COBs for tectonic modelling? Thanks!

    • AC2: Reply to CC2, Tim Minshull, 05 May 2020

      OK - I understand what you mean now. My answer would be something like: it depends what you are trying to achieve. I think for plate reconstructions you need isochrons, and COB/COT's are not isochrons, so not much good for that. But if you want to use observations from margins to learn about processes of continental breakup, you need to know which bits are continent, which are ocean and which are exhumed mantle. Of course this is not easy.  

      • CC3: Reply to AC2, Lucia Perez-Diaz, 05 May 2020

        Agreed - it is useful to know what is ocean and what isn't in that case. I guess my issue is mostly with how much weight is often still given to COBs in both kinematic and palinspastic modelling, despite the well-known uncertainties surroundign COB interpretation. Thanks for the quick reply, sorry I wasn't so clear first time around!