Autori: Ionescu, C., Hoeck, V., Tomek, C., Koller, F. Balintoni, I., Besutiu, L

Editorial: A.H.F. Robertson, S. Karamata and K. Šarić, Elsevier Science B.V., Lithos, 108, p.172-191, 2009.

Rezumat:

In the Transylvanian Depression (Romania) a number of deep wells were drilled to investigate and exploit
methane gas fields. From these, only a few penetrated the Middle to Upper Jurassic volcanics in the
basement. From three boreholes (Deleni, Cenade and Zoreni) rock samples were available for investigations.
Deleni and Cenade show calc-alkaline basalts to andesites which are similar to the island arc volcanics of the
Southern Apuseni Mountains. Zoreni basalts and basaltic andesites show a boninitic affinity, which was not
found up to now in outcrops. The distribution of the volcanics in the basement of the Transylvanian
Depression, which correlates with a geomagnetic anomaly, can be explained by the presence of a magnetiterich
ophiolite layer beneath the island arc volcanics. Comparable oceanic crust rocks are found further west,
in the Southern Apuseni Mountains. They are considered to be remnants of a marginal or back-arc basin, in
which a volcanic arc including boninites developed. Upon the westward-directed subduction of an open
ocean, the island arc and part of the back-arc basin were overthrusted eastwards onto continental crust
during the Late Jurassic or Early Cretaceous. A flip in the subduction direction caused late Early Cretaceous
westward thrusting of the back-arc basin and island arc rocks onto the crystalline basement of the Tisia
continent.

Cuvinte cheie: Mezozoic, Depresiunea Transilvaniei, Vulcanite de arc insular, Boninite, Subductie intra-oceanica // Mesozoic, Transylvanian Depression, Island arc volcanics, Boninites, Intra-oceanic subductionY

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