Some seismic signatures in the Romanian crust

Abstract

Some new seismic reflection data in the W of the Moesian platform, Focşani depression and Transylvania depression show seismic patterns which reflect the local structure and evolution of the each area. These local areas were affected by subsidence which over-printed the changes on the old pattern. The old and more or less reflective lower crust was fractured and some rigid blocks have preserved the reflectivity up to the present. The Ba˛ileşti section illustrates a transparent or diffractive upper crust and a well-marked lower crust by an alternation of reflective and non-reflective zones. The crystalline crust of the Râmnicu Sa˛rat section has two patterns: one relatively reflective, near the bottom of the depression (the W side), whilst the other, on the E flank of depression, is transparent. The E flank seems to be more fractured due to some tensile fractures originating in the bending stress during subsidence. The Târgu Mureşsection has a specific crustal pattern. A near-transparent crystalline crust overlies a very large crust-mantle transition zone which is fragmented in alternated reflective and transparent blocks.