Jurassic arc volcanism on Crimea (Ukraine): Implications for the paleo-subduction zone configuration of the Black Sea region

• Published in: Lithos Vol. 119; no. 3; pp. 412 - 426
• Main Authors: Meijers, M.J.M, Vrouwe, B., van Hinsbergen, D.J.J., Kuiper, K.F., Wijbrans, J., Davies, G.R., Stephenson, R.A., Kaymakcı, N., Matenco, L., Saintot, A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2010
• Subjects: 40Ar/39Ar dating; Arc volcanism; Black Sea region; Jurassic–Cretaceous; Tethys; X-ray fluorescence analysis; MED, Black Sea; MED, Ukraine; Laurasia; ANE, Europe; Tethys Sea; Arc volcanism; Jurassic–Cretaceous; X-ray fluorescence analysis; Tethys; 40Ar/39Ar dating; Black Sea region
• ISSN: 0024-4937; 1872-6143
• DOI: 10.1016/j.lithos.2010.07.017

The early Cretaceous and younger opening of the Black Sea has obliterated much of the older record of Tethyan subduction below southeastern Europe. The earlier Mesozoic evolution was dominated by opening and closure of Tethyan oceans between Gondwana and Laurasia with their consumption, at least in part, accommodated along the southern Eurasian margin. Crimea (Ukraine), a peninsula in the northern Black Sea, represents the northernmost region of southeastern Europe that exposes a record of a pre-Cretaceous Tethyan active margin. To shed new light on the paleosubduction zone configuration of the southeastern European margin in the Jurassic, we report
40Ar/
39Ar isotope dating on 10 samples and whole rock geochemistry on 31 samples from supposedly Jurassic magmatic rocks from the Crimean peninsula. The samples can be subdivided into two age groups: middle Jurassic (~
172–158
Ma) and uppermost Jurassic to lowermost Cretaceous (~
151–142
Ma), that both have a subduction-related geochemical signature. The ages of the younger group are in conflict with previously assigned biostratigraphic ages of the units under- and overlying the volcanic complex. This might suggest a scenario where the latter were juxtaposed by faulting. We argue that the Crimean volcanics represent a fragment of a volcanic arc overlying the southeastern European continental margin. These data therefore provide evidence for Jurassic northwards subduction below the Eurasian margin, preceding the opening of the Black Sea as a back-arc basin. We argue that the corresponding Jurassic trench was already positioned south of the Turkish Pontides and the Caucasus belt, implying a very shallow slab angle in the Jurassic.
►New constraints on paleosubduction zone configuration of southeastern European margin ►We report middle Jurassic to earliest Cretaceous
40Ar/
39Ar ages from Crimea (Ukraine) ►Whole rock geochemistry shows a subduction-related geochemical signature ►These data provide evidence for Jurassic northwards subduction below Eurasia ►We argue that the trench was positioned south of the Turkish Pontides and the Caucasus.