par CONSTANTIN CRANGANU
Université "Al. I. Cuza", Faculté de biologie-géographie-géologie
A model for the computation of the Transylvanian Basin subsidence is presented.
From the point of view of the initiation mechanism of subsidence, a distinction
between the thermic model and the stretching model is made. The thermic model
assumes: a) a thermic event preceding the subsidence; b) a modest raising
with erosion of a few hundreds meters; c) a thermic cooling fowling implicitly
by subsidence. The stretching model imagines a tectonic cause replacing the
thermic event. A second distinction between the sedimentary subsidence (due
to accumulation of great thicknesses sediments) which make that basin bottom
gradually plunge) and the tectonic subsidence (which takes place in a empty
basin or with a few sediments) is made. The influence of eustatic variation
on sedimentation is minutely presented with the help of a lot of balance
equations. Finally are presented the data on the Transylvania Basin paleo-sinking
with the help of 26 curves constructed on the basis of 26 drillings situated
between the Târnava Mica rivers, a zone with maximum thickness of sedimentary
deposits.
Key words: Thermic model, stretching model, sedimentary subsidence, tectonic
subsidence, eustatic variations.