Open AccessPetrography and geochemistry of granitoids and related rocks from the pre-Neogene basement of the Slavonia-Srijem Depression (Croatia)
Author(s) -
Sanja Šuica,
Vesnica Garašić,
Alan B. Woodland
Publication year - 2022
Publication title -
geologia croatica online/geologia croatica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.226
H-Index - 28
eISSN - 1333-4875
pISSN - 1330-030X
DOI - 10.4154/gc.2022.09
Subject(s) - geochemistry , geology , rhyolite , petrography , igneous rock , zircon , alkali basalt , amphibole , basement , alkali feldspar , pluton , petrology , feldspar , volcanic rock , quartz , volcano , paleontology , civil engineering , engineering , tectonics
The pre-Neogene basement of the Slavonia-Srijem Depression (eastern Croatia) is composed of various types of igneous, metamorphic and sedimentary rocks. Here we present the petrography and geochemistry of a heterogenous group represented by two types of alkali granite, granite, syenite, rhyolite and orthogneiss. The alkali granite type 1 has an A-type geochemical affinity: a ferroan character, high alkali content, high concentration of rare earth elements (REE3+), Rb, Zr, Nb and Y, and low CaO, MgO, P2O5, Ba, Sr and Eu contents. The syenite has similar characteristics, but displays enrichment in Ba, K, Eu and Zr, which could be a consequence of feldspar and zircon accumulation. The alkali granite type 2 is an A-type granite but differs from the alkali granite type 1 in having lower K2O and Rb, accompanied by higher Na2O and Sr concentrations, possibly resulting from alteration or a different parental magma/evolutionary process. The granite and rhyolite are distinguished from both types of alkali granite by their magnesian character, lower Zr, Nb and Y concentrations, less pronounced Eu negative anomaly, as well as higher Ba, Sr and LREE/HREE. The orthogneiss displays differences in major element chemistry compared to the alkali granite type 1, but has similar trace element and REE patterns. The alkali granites are characterized by Y/Nb<1.2, indicating an ocean island basalt-like source, while the granite originated from melting of a crustal, probably metasedimentary source. The A-type granites could belong to the Late Cretaceous A-type magmatism of the Sava Zone, while the granite is significantly different from the Sava Zone A-type granites as well as the other rocks investigated in this study.