The evolution of sedimentary basins and their thermal structure are the result of
the coupling between shallow crustal and deep lithospheric - mantle processes. When
sources of shallow crustal deformation are not detectable, then deep lithospheric
processes have the role to reveal the origin of these events. A particular method
of investigating these deep processes is to evaluate their lithospheric thermal imprint,
in particular when anomalous thermal values are exhibited. One such example is the
Transylvanian Basin situated at the interior of the highly bended Carpathians chain,
which shows lower heat flow values when compared with average cratonic values and
even lower when compared with the neighbouring Pannonian extensional basin. The basin
architecture suggests that a deep lithospheric - asthenospheric mechanism is responsible
for Middle - Late Miocene subsidence, coeval with phases of Carpathian collision.
The interplay between upper crustal evolution and deep lithospheric mechanics is investigated
by means of 2D lithospheric-scaled heat flow modelling, simulating the present-day
thermal regime of the basin. The heat flow correction for transient effects shows
the great importance of paleoclimate and sedimentation during the evolution of the
basin, calculated values being similar to 20% higher when compared with measured heat
flow. The modelling implies that the low values of heat flow are the result of a combination
of thermal effects of Middle - Upper Miocene sedimentation and the presence of depleted
rocks in the basin basement, with their thickness dependent on the amount of enrichment
in felsic magmatism during their evolution in a supra-subduction zone. The observations
infer a thinned lower part of the mantle during the Miocene evolution of the basin,
but the lithosphere thermal time constant suggests such changes do not affect the
thermal regime at present day. Larger effects in the SE part of the basin are likely
driven by the recent asthenospheric uplift due to the Vrancea slab descent.
