Petrogenesis and geodynamic evolution of the Kajan Neogene subvolcanic rocks,Nain, Central Iran |
| |
| Institution: | 1. Università degli Studi di Catania, Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Corso Italia 57, 95129 Catania, Italy;2. Università degli Studi di Siena, Dipartimento di Scienze Fisiche, della Terra e dell''Ambiente, Strada Laterina 8, 53100 Siena, Italy;3. Università degli Studi di Palermo, Dipartimento di Scienze della Terra e del Mare, Via Archirafi 22, 90134 Palermo, Italy;4. Consiglio Nazionale delle Ricerche, Istituto per l''Ambiente Marino Costiero, Via del Mare 3, 91021 Torretta Granitola (Campobello di Mazara, Trapani), Italy;5. Consiglio Nazionale delle Ricerche, Istituto per l''Ambiente Marino Costiero, Calata Porta di Massa, Interno Porto di Napoli, 80133 Napoli, Italy;1. Ghent University, Department of Geology, Renard Centre of Marine Geology, Campus Sterre S8, Krijgslaan 281, 9000 Ghent, Belgium;2. VLIZ – Flanders Marine Institute, Wandelaarkaai 7, 8400 Oostende, Belgium;3. MARUM – Center for Marine Environmental Sciences, Bremen University, Leobener Strasse, 28359 Bremen, Germany |
| |
| Abstract: | Kajan subvolcanic rocks in the Urumieh–Dokhtar magmatic arc (UDMA), Central Iran, form a Late Miocene-Pliocene shallow-level intrusion. These subvolcanics correspond to a variety of intermediate and felsic rocks, comprising quartz diorite, quartz monzodiorite, tonalite and granite. These lithologies are medium-K calc-alkaline, with SiO2 (wt.%) varying from 52% (wt.%) to 75 (wt.%). The major element chemical data also show that MgO, CaO, TiO2, P2O5, MnO, Al2O3 and Fe2O3 define linear trends with negative slopes against SiO2, whilst Na2O and K2O are positively correlated with silica. Contents of incompatible trace elements (e.g. Ba, Rb, Nb, La and Zr) become higher with increasing SiO2, whereas Sr shows an opposite behaviour. Chondrite-normalized multi-element patterns show enrichment in LILE relative to HFSE and troughs in Nb, P and Ti. These observations are typical of subduction related magmas that formed in an active continental margin. The Kajan rocks show a strong affinity with calc-alkaline arc magmas, confirmed by REE fractionation (LaN/YbN = 4.5–6.4) with moderate HREE fractionation (SmN/YbN = 1.08–1.57). The negative Eu anomaly (Eu/Eu* <1), the low to moderate Sr content (< 400 ppm) and the Dy/Yb values reflect plagioclase and hornblende (+- clinopyroxene) fractionation from a calc-alkaline melt Whole–rock Sr and Nd isotope analyses show that the 87Sr/86Sr initial ratios vary from 0.704432 to 0.705989, and the 143Nd/144Nd initial ratios go from 0.512722 to 0.512813. All the studied samples have similar Sr-Nd isotopes, indicating an origin from a similar source, with granite samples that has more radiogenic Sr and low radiogenic Nd isotopes, suggesting a minor interaction with upper crust during magma ascent. The Kajan subvolcanic rocks plot within the depleted mantle quadrant of the conventional Sr-Nd isotope diagram, a compositional region corresponding to mantle-derived igneous rocks. |
| |
| Keywords: | Urumieh–Dokhtar magmatic arc (UDMA) Magma differentiation Sr and Nd isotope ratios Calc-alkaline magmas |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
