In situ Rb-Sr dating of K-bearing minerals in the Gonen granitoid from the western Sakarya Zone, NW Anatolia

Granitoids with ages ranging from Paleozoic to Tertiary are widely distributed in the western Sakarya Zone. The Gospacing diaeresisnen granitoid is one of these Paleozoic (Early Carboniferous) granitoids and exposed on the western part of the Sakarya Zone in NW Anatolia. The Gospacing diaeresisnen granitoid is unconformably overlain by the Jurassic Bay & imath;rkospacing diaeresisy Formation consisting of conglomerate, sandstone, siltstone, and claystone intercalation. Medium to coarse-grained, yellowish brown-colored Gospacing diaeresisnen granitoid chiefly made up of K-feldspar, plagioclase, muscovite, quartz, and biotite. In this paper, it is presented in situ Rb-Sr isochron ages for the Gospacing diaeresisnen granitoid in the western Sakarya Zone. The isochron derived from muscovite and plagiocalse minerals occurring in the granitoid yielded 299.3 +/- 3.4 Ma (Late Carboniferous), which is interpreted as the emplacement age of the Gospacing diaeresisnen granitoid. This study also testifies that radiometric in situ Rb-Sr dating can be applied to resolve absolute dating of magmatic complexes. According to the initial 87Sr/86Sr ratio, the magma producing the Gospacing diaeresisnen granitoid was derived from the enriched subcontinental lithospheric mantle forming the ancient crust. The Carboniferous magmatic event can be attributed to the northward subduction of the Palae-Tethys oceanic crust along the southern margin of Laurasia in the Early-Late Carboniferous.