SHRIMP GEOCHRONOLOGY OF GRANITOID ROCKS IN THE SOUTHERN ANATOLIDE BELT, WESTERN TURKEY

U–Pb dating of magmatic zircons with the Sensitive High-mass Resolution Ion Microprobe (SHRIMP) resolves the disputed age of granitoid magmatism and deformation history in the western Turkish portion of the Alpine-Himalaya chain.

Magmatic zircon grains from granitoid intrusions in key structural outcrops of the Çine submassif in the southern Anatolide belt invariably yield Pan-African ages.

Homogeneous long-prismatic grains and rims of pyramidal-prismatic grains are Neoproterozoic to earliest Cambrian in age, while core ages range from Palaeoproterozoic to Neoproterozoic. Cathodoluminescence (CL) imaging combined with statistical treatment of the isotope data lead to crystallisation ages of the analysed granites at 541±14 Ma and 566±6 Ma.

This suggests that crystalline basement rocks in much of the Anatolide belt were deformed, metamorphosed and intruded in the late Neoproterozoic to earliest Cambrian, and neither crystallised nor remelted during Alpine convergence, which effectively rules out the possibility of remelting or high-grade metamorphism related to a Tertiary event.

Structural and metamorphic evidence for Alpine convergence in Pan-African basement rocks is limited to greenschist facies top-to south shear zones, which occur across a number of tectonic units on a regional scale and are likely to relate to the assembly of the Anatolide belt in the early Tertiary.