Petrochronological Evidence for a Three-Stage Magmatic Evolution of the Youngest Nepheline Syenites from the Ditrău Alkaline Massif, Romania

The Ditrău Alkaline Massif (DAM) is an igneous massif in the Eastern Carpathian Mountains of Romania. Numerous geochronological and geochemical studies have proposed a long formation history (ca. 70 m.y.) DAM from Middle Triassic to Cretaceous times, which hardly reconcilable with evolutionary models geotectonic environment during Mesozoic this part Mountains. In order put tighter age constraints on processes forming DAM, two nepheline syenites so-called Ghiduţ Lăzarea suites were investigated. Based field evidence, rock represent younger intrusives. Detailed zircon characterization, situ SIMS U-Pb dating, modelling used establish timing crystallization thus set time these parts DAM. intrusion dated suite sample took place at 232 ± 1 Ma Karnium, whereas syenite was intruded 225 Norium. Together published data, three different magmatic events can be identified: 231.1 0.8 Ma, 230.7 0.2 224.9 1.1 Ma. Although ages 2 are statistically indistinguishable, combination petrochronological data certainly favor independent events. Thus, encompassed span ca. 13 m.y. Additionally, each event tentatively divided older syenitic stage one, difference some 100,000 years. No indication any post 215 or hydrothermal activity found. new interpretation significantly improve our understanding temporal evolution alkaline complexes as such, demonstrating that underlying (melt generation, assimilation, fractionation, duration plumbing systems) work same scale for both sorts suites.