Migration of RomUkrSeis WARR data reveals complex basement structure for the area of accretion of Tisza–Dacia microplate to the East European Craton

The RomUkrSeis profile is a 675-km long WARR (wide-angle reflection and refraction) SW–NE trending profile running from the Apuseni Mountains and Transylvanian Basin to the East European Craton. To achieve a more detailed seismic image of the basement and upper crust, we applied finite-difference migration of refracted and reflected waves to the RomUkrSeis data. The new migration image allows elucidation of the Carpathian accretionary prism in the central part of the profile, as well as the Teisseyre-Tornquist Zone. This zone separates the cratonic segment in the northeast from the Tisza–Dacia terrain in the southwest. The new image of the cratonic block reveals a high-reflectivity dome-like structure related to the Archean cratonic basement of the Ukrainian Shield (Podolian Block) and underneath the Volyn-Podolian Monocline. Here, a high reflectivity boundary at ≥ 20 km depth and deepening SW toward the Carpathians likely represents the cratonic crystalline basement, overlain by thick succession of Ediacaran metasedimentary rocks formed during Rodinia break-up. To the SW of the Eastern Carpathians the profile passes along the junction of the Tisza and Dacia terranes, revealing a collage of blocks of different wave image patterns and affinity. The collage includes the unrooted block of the Apuseni ophiolite complex, Tisza and Dacia crystalline basement domains with a southwestward narrowing zone of high reflectivity in the deep part of the Dacia terrane, which is interpreted as a suture zone between Tisza and Dacia. A transparent block in the Inner Carpathians area likely belongs to the upper crust with abundant Neogene magmatic bodies.