Source constraints on the genesis of Danubian granites in the South Carpathians Alpine Belt (Romania)
Authors
Duchesne, J.C.
Laurent, O.
Gerdes, A.
Bonin, B.
Liégeois, J.P.
Tatu, M.
Berza, T.
Discipline
Earth and related Environmental sciences
Subject
Geodynamics and mineral resources
Audience
Scientific
Date
2017Metadata
Show full item recordDescription
The pre-Alpine basement of the Lower Danubian nappes in the South Carpathians ismade up of two Precambrian terranes (Drăgşan and Lainici-Păiuş) that were intruded by Pan-African/Cadomian and Variscan granitoid massifs. We focus on the major and trace element geochemistry (1) in the Drăgşan terrane, of the Variscan Retezat and Parâng intrusions; (2) in the Lainici-Păiuş terrane, of the Variscan Furcǎtura, Petreanu and Frumosu intrusions and of the Pan-African Vârful Pietrii, Şuşiţa and Olteţ granites and granitic leucosomes of migmatites; and (3) in the Upper Danubian nappes basement, of the VariscanMunteleMic, Sfârdin, Cherbelezu and Ogradena intrusions. For each intrusion, in which a range of composition is observed, we decipher the differentiation mechanisms (fractional crystallization, hybridization, melt laden with restite minerals, etc.) in order to define the parental liquid compositions. The latter are calc-alkaline to alkali-calcic (except Olteţ that is calcic) and mediumto high-K in composition.With [La/Yb]N N 10 and Sr/Y N 15,mostmelts display the so-called continental adakite affinities. The parental melt compositions are compared with experimental data to determine the melting conditions and the nature of the source rock. When the P-T conditions can be estimated, the temperatures range between 850 °C and 875 °C and the pressure between 5 and 15 kbar regardless of the ages of the granites and the terrane in which they have intruded. The source rock composition is dominated by a variety of mafic igneous compositions or metasediments rich in volcanic components. Clay-rich (pelitic) protoliths have not been identified. We confirm a Variscan age (c. 300 Ma) for the Frumosu intrusion granite and inherited Precambrian ages (c. 1.7 1.9 and 2.6 2.9 Ga) for the Motru dyke swarm. Thus, both Drăgşan and Lainici-Păiuş together with the Upper Danubian basement terranes were affected by Variscan post-collisional granitic plutonism. In the South Carpathians, both Pan-African and Variscan granites were generated in a crust thickened by stacking of terranes. The source of the Pan-African granites in Lainici-Păiuş is different from that of the Variscan granites (from Lainici-Păiuş and Drăgşan terranes and from the Upper Danubian nappe basement), but all these sources were notably depleted in metapelite component.
Citation
Duchesne, J.C.; Laurent, O.; Gerdes, A.; Bonin, B.; Liégeois, J.P.; Tatu, M.; Berza, T. (2017). Source constraints on the genesis of Danubian granites in the South Carpathians Alpine Belt (Romania). , Lithos, Vol. 294-295, 198-221,Identifiers
Type
Article
Peer-Review
Yes
Language
eng