GRANITOID ROCKS OF THE VELKA FATRA MTS. — Rb/Sr ISOTOPE GEOCHRONOLOGY (WESTERN CARPATHIANS, SLOVAKIA)

Year, pages: 1996, 81 - 89

Isotope study of granitoid rocks of the Lubochna Massif in the Velka Fatra Mts. has been carried out on whole-rock (WR) samples and separated mineral phases (muscovite, biotite) using the Rb/Sr method. It confirmed the long duration of the granitoid magmatism with "re-cycled" crustal-mantle source material (I_Sr = 0.7057). During the main Meso-Hercynian event (350–340 Ma) the crust tectonically thickened. As a result of the collision of the upper overheated unit with the lower, cooler one, the anatectic Lubochna leucogranites (LLG) in the middle crust were melted. In the subsequent, extension phase, these leucogranites were emplaced into the upper cover unit, into the block of the "relatively older crystalline complex", composed of the Smrekovica tonalites (ST), Kornietov granodiorites (KGD) and Lipova granites (LG), which were also partly melted and re-magmatised, however, preserving their original composition and zoning. This event is documented by the WR, Bi, Mu isochron (340 Ma) for all rock types. The age of the pre-existing granitoid body (ST, KGD and LG), showing an "inherited isochron" with an apparent age of 420 Ma is problematic. More than 340 Ma ago, this zoned Velka Fatra pluton, like the Eo-Hercynian crystalline block, was probably already isotopically homogenized and solidified. The presented study confirmed that during the Meso-Hercynian stage there was no isotopic homogenization affecting the whole Velka Fatra pluton. Only local ⁸⁷Sr/⁸⁶Sr isotopic homogenization has been recorded.

Kohut, M., Carl, C., Michalko, J. 1996. GRANITOID ROCKS OF THE VELKA FATRA MTS. — Rb/Sr ISOTOPE GEOCHRONOLOGY (WESTERN CARPATHIANS, SLOVAKIA). In Geologica Carpathica, vol. 47, no.2, pp. 81-89. 1335-0552.

Kohut, M., Carl, C., Michalko, J. (1996). GRANITOID ROCKS OF THE VELKA FATRA MTS. — Rb/Sr ISOTOPE GEOCHRONOLOGY (WESTERN CARPATHIANS, SLOVAKIA). Geologica Carpathica, 47(2), 81-89. 1335-0552.