Plate tectonics on the Romanian territory as inferred from geophysical data

Plate tectonics on the Romanian territory still represents a challenge to geoscientists. Several previous models were mainly based on geological arguments (ophiolitic scares) and almost never on the geophysical behavior of a plate boundary. Starting from the potential field information, the paper represents an attempt to outline plate wedges and their dynamics based on geophysical data interpretation. Gravity, and geomagnetic maps, heat flow, geomagnetic induction vector, earthquakes, and deep seismic (DSS) and magnetotelluric (MTS) data were used on purpose. Consequently, a three-plate tectonic model has been considered. East European Plate (EEP), Moesian microplate (MoP), and Intracarpathian microplate (IaP) seem to meet into the Vrancea area, which active seismicity has been considered to be due to the presence of a continental unstable transform-transform-compression triple-junction. They are separated by Tornquist-Teisseyre Zone (TTZ), Trans-Getica Fault (TGF) and Peceneaga-Camena Fault (PCF). The SE extension of TTZ, as the contact between EEP and IaP, was revealed on the Romanian territory. Its Moho “keel”, pointed out by DSS on Polish and Ukrainian territories, was MTS confirmed from the northern state border to the Vrancea area, and well reflected in the gravity data too. The sharp end of the geomagnetic pattern of the buried North Dobrogea structures toward Carpathians, and the presence of an important electric discontinuity separating two compartments with distinct lithosphere thickness (220/150 km) support the hypothesis. Unlike previous models, the authors consider that TTZ does not extend towards the Black Sea. Instead, it might be broken and shifted westward along a second major lithosphere contact, TGF, the northern wedge of MoP. TGF was sharply outlined at least at the basement level, in the filtered images of the geomagnetic anomaly in the southern part of South Carpathians. The divergence of Wiese vectors along it advocates for the presence of an active fault in the lower crust of the area. Regional stress and active seismicity in the area are evidence for its transform nature. A third major lithospheric contact, PCF, represents the boundary between EEP and MoP. Its crustal nature was revealed by DSS data, showing a step of about 10 km at the both Moho and Conrad boundaries. Recent studies on PCF kinematics, and stress tensor data advocate for its transform nature. Some considerations are also made on the crust and lithosphere thickness of each of the discriminated compartments. A brief scenario connected to the Black Sea opening is used to describe timing and dynamics of the revealed lithosphere blocks.