SW limit of the East European Platform (Romania) – insight from Palaeozoic kinematics

Abstract

The limits of the East European Platform (EEP) are debated to the present day. Some researchers consider that areas of the platform whose basement has suffered Caledonian or younger tectogenesis are no longer part of the platform, but they belong to a younger one even more to the West. When establishing the limits of this Platform, it’s very difficult considering the thick sedimentary cover that overlays the basement or that the Carpathian thrusts are hiding it. For the Western border of the Platform, some consider it to be represented by the Transeuropean Suture Zone but a second hypothesis places this limit on the Ustilug-Rohatin fault which would associate a large block of the platform to a much younger one to the West. Overlying the basement there is a series of almost horizontal sedimentary successions starting from Ediacaran and Ordovician which have been dated through fossil studies. The Cambrian sedimentary succession is missing in some parts of the platform. This paper’s aim is to bring new insights in regards to the South-Western limit of the EEP which is covered in Romania by the Carpathian nappes. The structural image of this limit is very important for the dynamics of the basement and the influence it had over the entire region, and ultimately to have a better control over the hydrocarbon potential in the deeper systems of the area. The severe lack of well data and deep seismic imaging is a real problem that only puts extra burdens on the research. Several deep refraction seismic profiles were shot in the past and they were used in the subsequent studies drawing the mentioned theories about the platform boundaries. Using modern interpretation of the information from the intensively explored areas for hydrocarbons, including well data, reflection seismic profiles combined with the published interpretations from the deep refraction profiles, the structural image of the South-Western boundary and its dynamics is starting to take shape. The kinematics of the fault systems of the Palaeozoic at its different levels are highlighted on seismic profiles on syn-kinematic wedges. Several structural maps were drawn for the Palaeozoic and base Mezozoic and different fault systems are easily identified. This could have an influence over the information currently theorized about the EEC/WEP contact zone. Our results show the presence of a large NNE-SSW fault oriented system, with a cumulative fault offset of 1 km. The fault offset was established during the Palaeozoic as proven on the presence of syn-kinematic sedimentation. The importance of knowing the regional evolution of the Eastern side of the WEP is important especially for understanding the unexplored deeper hydrocarbons systems. Their presence or lack thereof could be well influenced by these processes.

AAPG Datapages/Search and Discovery Article #90325 © 2018 AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin, Lisbon, Portugal, May 2-3, 2018