Research Information System
EGU Genral Assembly 2016, Viyena, Austria, 17 - 22 April 2016, vol.18, no.20164561, pp.456
Massive, fine-grained metavolcanic rocks of the Çamlıca metamorphic unit exposed in the Biga Peninsula, northwest Turkey, have provided new Carboniferous ages and arc-related calc-alkaline volcanics indicating that the
Biga Peninsula was possibly involved in the Variscan orogeny. The metavolcanic rocks are mainly composed of
metalava- metatuff intercalation and have an andesitic composition. Chondrite-normalized REE patterns within
these rocks are fractionated (LaN/YbN ∼ 2.2 to 8.9), Europium anomalies are slightly variable (Eu/Eu* 0.6 to
0.7) and generally negative (average Eu/Eu* 0.68). The metavolcanic rocks have a distinct negative Nb anomaly
and negative Sr, Hf, Ba and Zr anomalies. These large negative anomalies indicate crustal involvement in their
derivation. The crustal influence may be related to either partial melting at the base of continental crust or contamination of mafic magma with crustal material. Tectonic discrimination diagrams show that all metavolcanic rocks
were formed within a volcanic arc setting. Zircon ages (LA-ICPMS) of two samples yield 333.5±2.7 Ma and
334.0±4.8 Ma. These ages are interpreted to be the time of protolith crystallization. This volcanic episode in the
Biga Peninsula can be correlated with the Central Europian Variscides. Carboniferous calc-alkaline magmatism in
the Sakarya Zone can be ascribed to arc-magmatism as a result of northward subduction of the Palaeo-Tethys under
the southern margin of Laurasia. Geochemical and U-Pb zircon data indicate that the Sakarya Zone is strikingly
similar to that of the Armorican terranes in central Europe. The Biga Peninsula can provide a link between the
Sakarya Zone and the Armorican terranes.