CHEMIE DER ERDE-GEOCHEMISTRY, vol.71, no.1, pp.59-75, 2011 (SCI-Expanded)
The Koprubasi intrusion from the eastern Pontides of NE Turkey consists of granodiorite and monzogranite, and contains a number of mafic microgranular enclaves (MMEs). We report here U-Pb zircon age, geochemical and Sr-Nd isotopic data for these rocks in order to determining magma sources and magma production processes. On the basis of U-Pb zircon sensitive high-resolution ion microprobe dating (SHRIMP), the magma emplacement age of the granodiorite is 79.3 +/- 1.4 Ma. The rocks of the pluton are calc-alkaline, metaluminous to peraluminous characteristics, and display features of I-type granites. They are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) with negative Eu anomalies (Eu/Eu* = 0.60-0.76), but are depleted in high field strength elements (HFSE). They have small range of (87)Sr/(86)Sr((i)) (0.7067-0.7070) and epsilon(Nd(i)) (-3.2 to -4.4) values. Fractionation of plagioclase, hornblende and Fe-Ti oxides played an important role in the evolution of the Koprubasi intrusion. A relatively shallow intrusion depth (similar to 2-8 km) was estimated from the Al-in-hornblende geobarometry. All these characteristics, combined with the low values of K(2)O/Na(2)O, SiO(2), Al(2)O(3)/(FeO(T) + MgO + TiO(2)) and (Na(2)O + K(2)O)/(FeO(T) + MgO + TiO(2)), suggest an origin by dehydration melting from a metabasaltic lower crustal source. (C) 2010 Elsevier GmbH. All rights reserved.