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Rezumat articol ediţie STUDIA UNIVERSITATIS BABEĹž-BOLYAI
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Rezumat: Two types of volcanism developed in Gutâi Mts. (inner volcanic chain of Eastern Carpathians): a felsic, extensional/“back-arc” type and an intermediate, arc type.
The felsic volcanism of explosive origin, consisting of caldera-related rhyolitic ignimbrites and resedimented volcaniclastics, had taken place during Early-Middle Badenian and Early Sarmatian.
The intermediate volcanism, consisting of extrusive (effusive and explosive) and intrusive activity, had developed during Sarmatian and Pannonian (13.4-7.0 Ma). It is represented by typical calc-alkaline series, from basalts to rhyolites. Lava flows of basaltic andesites and andesites are predominant, often emplaced in subaqueous environment. Extrusive domes, mainly composed of dacites, are associated to the andesitic volcanic structures.
The intrusive volcanic activity developed contemporaneously with the paroxysm of the intermediate volcanism. The intrusive rocks consist mainly of porphyritic aspects of a compositional series from gabbroes to granodiorites.
The geochemical study on the volcanic rocks shows the calc-alkaline character of both felsic and intermediate volcanism and typical subduction zones geochemical signatures for the intermediate one. The felsic volcanism shows affinities with subduction-related rocks as well. The main petrogenetic process in Gutâi Mts. was crustal assimilation, strongly constrained by trace element and isotope geochemistry. |
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