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The Miocene–Pliocene subsidence of the tectonic platforms in the Romanian Carpathians foreland is analysed using standard 1D backstripping techniques for individual wells, combined in two regional sections and six contour maps. The subsidence patterns were integrated together with previous paleostress and kinematic studies, in order to derive the Tertiary kinematics of the buried faults in the Carpathians lower plate. The study revealed accelerated subsidence during the Early Miocene in the western part of the Moesian Platform/Getic Depression, in direct relationship with the opening of a WSW–ENE trending extensional basin. The largest subsidence recorded in the front of the Carpathians took place during the Late Miocene, due to final E-ward emplacement of the thrust sheets. The Late Miocene subsidence showed anomalous high values between the Intramoesian and Trotus faults as a result of the orogenic collision with the East-European Platform northward and acceleration of the subduction process in the SE Carpathians corner. Further Pliocene subsidence continued only in the latter region, the depocenter being shifted southward near the junction with the South Carpathians foreland. [Copyright &y& Elsevier]

Abstract: The DACIA PLAN (Danube and Carpathian Integrated Action on Process in the Lithosphere and Neotectonics) deep seismic sounding survey was performed in August–September 2001 in south-eastern Romania, at the same time as the regional deep refraction seismic survey VRANCEA 2001. The main goal of the experiment was to obtain new information on the deep structure of the external Carpathians nappes and the architecture of Tertiary/Quaternary basins developed within and adjacent to the seismically-active Vrancea zone, including the Focsani Basin. The seismic reflection line had a WNW–ESE orientation, running from internal East Carpathians units, across the mountainous south-eastern Carpathians, and the foreland Focsani Basin towards the Danube Delta. There were 131 shot points along the profile, with about 1 km spacing, and data were recorded with stand-alone RefTek-125s (also known as “Texans”), supplied by the University Texas at El Paso and the PASSCAL Institute. The entire line was recorded in three deployments, using about 340 receivers in the first deployment and 640 receivers in each of the other two deployments. The resulting deep seismic reflection stacks, processed to 20 s along the entire profile and to 10 s in the eastern Focsani Basin, are presented here. The regional architecture of the latter, interpreted in the context of abundant independent constraint from exploration seismic and subsurface data, is well imaged. Image quality within and beneath the thrust belt is of much poorer quality. Nevertheless, there is good evidence to suggest that a thick (∼10 km) sedimentary basin having the structure of a graben and of indeterminate age underlies the westernmost part of the Focsani Basin, in the depth range 10–25 km. Most of the crustal depth seismicity observed in the Vrancea zone (as opposed to the more intense upper mantle seismicity) appears to be associated with this sedimentary basin. The sedimentary successions within this basin and other horizons visible further to the west, beneath the Carpathian nappes, suggest that the geometry of the Neogene and recent uplift observed in the Vrancea zone, likely coupled with contemporaneous rapid subsidence in the foreland, is detached from deeper levels of the crust at about 10 km depth. The Moho lies at a depth of about 40 km along the profile, its poor expression in the reflection stack being strengthened by independent estimates from the refraction data. Given the apparent thickness of the (meta)sedimentary supracrustal units, the crystalline crust beneath this area is quite thin (<20 km) supporting the hypothesis that there may have been delamination of (lower) continental crust in this area involved in the evolution of the seismic Vrancea zone. [Copyright &y& Elsevier]

Abstract: Results are presented from GPS measurements performed in the Southeastern Carpathians between 1997 and 2004. Data from 25 stations observed during 13 campaigns were analyzed by the Department of Earth Observation and Space Systems (DEOS) of Delft University of Technology. The repeatabilities of the solutions are on the order of 1–4 mm for the horizontal, and 4–8 mm for the vertical component. The resulting velocity estimates have an uncertainty of <1 mm/yr and <3 mm/yr, respectively. The region southeast of the Carpathian bend zone shows a horizontal movement towards SSE of ∼2.5 mm/yr, while the Transylvanian Basin shows very small motions with respect to Eurasia. The vertical velocity field indicates the existence of uplift and subsidence domains in the SE Carpathians, in good agreement with Pliocene–Quaternary orogen and basin studies. Another 29 GPS stations installed in the last 3 yr will generate a denser velocity field in the coming years for this region. [Copyright &y& Elsevier]

It has been widely documented that the depth of foredeeps does not always reflect the topography of the neighboring orogens. In many cases, the topographic load is insufficient to explain basin subsidence. Such is the case of the SE Carpathians where an anomalously deep (almost 13 km) foreland basin has evolved since the Middle Miocene (Badenian). A peculiar feature of this basin is its position relative to the orogen. In contrast to typical foredeeps, which deepen towards the belt, the maximum depth of this basin is 10–20 km out of the orogen. The subsidence in the Carpathians Bend foreland is characterized by two stages: the first is Middle Miocene (Badenian) in age and is related to NE–SW extension when fault-bounded basins were formed. Modeling shows that the foreland underwent small pre-orogenic uniform thinning. The modeling also predicts <100 m post-rift subsidence in accordance with the regional unconformity observed at the Middle/Upper Miocene (Badenian/Sarmatian) boundary. The second subsidence stage follows rifting and is caused by flexural loading of the Carpathians nappes. According to the planform flexural modeling results, the location of depocenter in front of the Carpathians Bend in the latter contractional stage can be accounted for by the present topography if lateral variations in lithospheric strength are taken into account. Since the depth of the predicted basin is half of what is actually observed, an extra-load is required, which is equivalent to 500–800 m in terms of extra topography. In this case, the predicted basin corresponds with the observed geometry in terms of position/shape and depth, the latter depending on the magnitude of intraplate stresses as well. The modeling also suggests that the flexural fore-bulge of the Carpathians system is represented by the uplifted Dobrogea. Our explanation for the large subsidence recorded by the SE Carpathians foredeep highlights the control exerted by lateral changes in lithospheric strength on 3-D subsidence patterns in arcuate orogenic belts. [Copyright &y& Elsevier]