Akademik Veri Yönetim Sistemi
10.Geochemistry Symposium, Antalya, Türkiye, 17 - 19 Ekim 2024, cilt.1, sa.1, ss.1
LA-ICP-MS zircon geochronology and geochemistry
(whole-rock & mineral chemistry) from the Misis-Andirin Complex (MAC)
volcanic rocks are reported. The MAC records magmatic, sedimentary, and
tectonic processes operating at the northern active margin of the Neotethys
(South Tethys) in the eastern Mediterranean district. The MAC represents an
association of an originally active continental margin including the Engizek
(in the NE), Andirin (central) and Misis (in the SW) segments. The felsic
extrusives are depleted in HFSE (high-field-strength elements), enriched in
LILE (large-ion lithophile elements) and have flat-type REE patterns; these
trends and also biotite chemistry verify their supra-subduction zone tectonic
environment. The studied volcanic unit consists of mainly rhyolite, dacite and
rare andesite rocks, and is intercalated with Bulgurkaya Formation. These
felsic extrusive rocks show relative depletions in Ti + Nb, and partial
enrichment in Cs, Rb, Ba, and Th in the N-MORB (normal-mid ocean ridge basalt)
normalized spider plot, suggesting their derivation from a supra-subduction
geodynamic environment. The La/Nb (1.92–2.33) and Nb/Th (1.0–1.12) ratios of
all the analysed extrusives from Andirin region present arc magmas or volcanic
rocks affinity that could have been contributed by crustal source contents and
also examined volcanics yield nearly flat Ba/La ratios with relatively
increasing Th/Yb, suggesting the contribution of sediments or crustal
contamination. The Al-in-hornblende thermobarometry (2.04 to 1.55 kbar) of
Mg-Fe hornblende in the volcanics of the MAC represents their crystallization
of amphibole in the moderate to shallow crustal level at a maximum 6.7 km to a
minimum 5.1 km depth. The ilmenite-magnetite thermometer based on Fe-Ti oxide equilibria
shows that the Andirin region felsic magmas were at 717℃ and at an ƒO2
of approximately 2.16 log units (+1.51 NNO). The MAC extrusive volcanic rocks
were produced throughout the Eocene period, and our new U-Pb zircon dating
(47.13 ± 0.5 Ma) confirmed mainly younger Lutetian age of the volcanic activity
in the Andirin area.