Published: 2026-08-21
Granitic magmatism at the Adria–Europe boundary during the waning of Neotethys: Geochemical and geochronological insights from the Sava Zone, Pannonian Basin (Croatia)
Authors: Sanja Šuica, Dejan Prelević, István Dunkl, Jin-Cheng Xie, Vesnica Garašić, Alan B. Woodland, Nina Trinajstić, Mihovil Brlek
Abstract:
In southeastern Europe, the Late Cretaceous Sava Zone igneous rocks consisting of tholeiitic and alkaline basalts, rhyolites and minor A-type granites were interpreted as intraoceanic or fore-arc. This view had strong impact on regional interpretation, proposing that Neothetys ocean did not close during the Mid-Late Jurassic ophiolite obduction but remained open in the Late Cretaceous. The Sava zone is largely covered by deposits of the Pannonian Basin. The Late Cretaceous igneous rocks from the boreholes in eastern Croatia were subjected to geochemical, in situ zircon U-Pb dating and Hf in zircon isotope analysis. Drava depression is situated in the upper-plate Tisia megaunit, and the orthogneiss with Late Permian A-type protolith (257 ± 2.6 Ma, εHf(i) = +2.4 to −3.1) placed the studied part of Slavonia-Srijem depression within the same unit. Drava hosts calc-alkaline to high-K calc-alkaline I-type granodiorite-monzodiorite (77.3 ± 1.1 Ma, εHf(i) = +3.3 to −3.2), with microgranular mafic enclaves, and hybrid quartz-monzodioritic rocks originating from magma-mixing. Slavonia-Srijem hosts A-type alkali-feldspar granites and quartz-alkali-feldspar syenite (83.7 ± 0.6 to 78.8 ± 0.7 Ma; εHf(i) = +9.7 to −0.8). Both suites were generated by mixing of mantle and continental crust-derived melts and display geochemical affinity towards Sava Zone, but distinction arise from lower thickness of crust in Slavonia-Srijem. They point to intracontinental origin of Sava Zone magmatism, caused by asthenosphere uprise, proving the absence of ocean in the Late Cretaceous, and indicating complex (post-)collisional processes as a trigger for magmatism.
In southeastern Europe, the Late Cretaceous Sava Zone igneous rocks consisting of tholeiitic and alkaline basalts, rhyolites and minor A-type granites were interpreted as intraoceanic or fore-arc. This view had strong impact on regional interpretation, proposing that Neothetys ocean did not close during the Mid-Late Jurassic ophiolite obduction but remained open in the Late Cretaceous. The Sava zone is largely covered by deposits of the Pannonian Basin. The Late Cretaceous igneous rocks from the boreholes in eastern Croatia were subjected to geochemical, in situ zircon U-Pb dating and Hf in zircon isotope analysis. Drava depression is situated in the upper-plate Tisia megaunit, and the orthogneiss with Late Permian A-type protolith (257 ± 2.6 Ma, εHf(i) = +2.4 to −3.1) placed the studied part of Slavonia-Srijem depression within the same unit. Drava hosts calc-alkaline to high-K calc-alkaline I-type granodiorite-monzodiorite (77.3 ± 1.1 Ma, εHf(i) = +3.3 to −3.2), with microgranular mafic enclaves, and hybrid quartz-monzodioritic rocks originating from magma-mixing. Slavonia-Srijem hosts A-type alkali-feldspar granites and quartz-alkali-feldspar syenite (83.7 ± 0.6 to 78.8 ± 0.7 Ma; εHf(i) = +9.7 to −0.8). Both suites were generated by mixing of mantle and continental crust-derived melts and display geochemical affinity towards Sava Zone, but distinction arise from lower thickness of crust in Slavonia-Srijem. They point to intracontinental origin of Sava Zone magmatism, caused by asthenosphere uprise, proving the absence of ocean in the Late Cretaceous, and indicating complex (post-)collisional processes as a trigger for magmatism.
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