Contemporaneous crust-derived I- and S-type granite magmatism and normal faulting on Tinos, Delos, and Naxos, Greece: Constraints on Aegean orogenic collapse

Aegean orogenic collapse occurred around 15 million years ago, marked by the simultaneous intrusion of I-type and S-type granite magmas alongside normal faulting on the Cycladic islands of Tinos, Delos, and Naxos. The study reveals that these granitoids, derived from crustal anatexis of variable metaigneous and metasedimentary sources, are unrelated to Hellenic subduction. I-type granites originated from dehydration melting of igneous basement protoliths, while S-type leucogranites formed via muscovite dehydration melting of sedimentary rocks. Field observations, geochemistry, Sr-Nd isotopes, and U-Pb geochronology constrain the timing of extensional structures, indicating that top-to-the-(N)NE shear zones active from 20 to 15 Ma were later folded and cut by normal faults. This transition from compressional to extensional stress fields signifies a critical phase in Aegean tectonic evolution.

Lamont, T. N., Roberts, N. M. W., Searle, M. P., Gardiner, N. J., Gopon, P., Hsieh, Y.-T., Holdship, P., & White, R. W. (2023). Contemporaneous crust-derived I- and S-type granite magmatism and normal faulting on Tinos, Delos, and Naxos, Greece: Constraints on Aegean orogenic collapse. GSA Bulletin. https://doi.org/10.1130/b36489.1