Extension-related Miocene calc-alkaline magmatism in the Apuseni Mountains, Romania

Origin of magmas

Emilian Roşu, Ioan Seghedi, Hilary Downes, David H M Alderton, Alexandru Szakács, Z. Pécskay, Cristian Panaiotu, Cristina Emilia Panaiotu, Liviu Nedelcu

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

The Miocene magmatism of the Apuseni Mountains in the Carpatho-Pannonian area hosts some of Europe's largest porphyry epithermal Cu-Au ore systems associated with shallow subvolcanic intrusions. Detailed field observations combined with K-Ar ages, geochemical analyses, Sr-Nd isotopes and paleomagnetic data constrain a model for the geotectonic evolution and processes of melt generation that may account for the exceptional mineralizing potential of the magmatic activity in this region. The magmatic activity developed mainly between 14.7 and 7.4 Ma and after a gap ceased at around 1.6 Ma. Geotectonic conditions do not support contemporaneous subduction processes, but were represented by transtensional and rotational tectonics, which generated horst and graben structures and favoured the generation and ascent of magmas. The "subduction signature" of the magmas emphasizes the significant involvement of fluids (mantle lithosphere and/or lower crust) inherited during previous geodynamic events. The mechanism of magmagenesis is considered to be related to decompressional melting (various degrees of) of a heterogeneous source situated at the crust-lithosphere mantle boundary. Mixing with asthenospheric melts generated during the extension-related attenuation of the lithosphere may also be implied. The evolution from normal to adakitic-like calc-alkaline and alkaline magmas generally is time-dependent as a consequence of variable fluid-present melting. Fractional crystallization-assimilation processes in shallow magma chambers are suggested for early magmatism but were almost absent from later magmatism, which related to an increasingly extensional regime. The youngest alkalic (shoshonitic) magmatism (1.6 Ma) is asthenosphere-derived, but in a different extensional event, being almost coeval with the OIB-like alkali-basaltic magmatism (2.5 Ma) occurring along the South Transylvanian fault. The fluid-present melting of the source seems to be the critical factor for the presence of the copper-gold-bearing mineralizing fluids.

Original languageEnglish
Pages (from-to)153-172
Number of pages20
JournalSchweizerische Mineralogische und Petrographische Mitteilungen
Volume84
Issue number1-2
Publication statusPublished - 2004

Fingerprint

magmatism
Miocene
Melting
mountain
Fluids
lithosphere
fluid
melting
Bearings (structural)
Geodynamics
subduction
melt
mantle
Alkalies
Tectonics
Crystallization
Isotopes
Gold
ocean island basalt
Ores

Keywords

  • Adakite-like
  • Alkaline
  • Apuseni Mountains
  • Calc-alkaline
  • Extension
  • Miocene
  • Romania

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

Cite this

Extension-related Miocene calc-alkaline magmatism in the Apuseni Mountains, Romania : Origin of magmas. / Roşu, Emilian; Seghedi, Ioan; Downes, Hilary; Alderton, David H M; Szakács, Alexandru; Pécskay, Z.; Panaiotu, Cristian; Panaiotu, Cristina Emilia; Nedelcu, Liviu.

In: Schweizerische Mineralogische und Petrographische Mitteilungen, Vol. 84, No. 1-2, 2004, p. 153-172.

Research output: Contribution to journalArticle

Roşu, E, Seghedi, I, Downes, H, Alderton, DHM, Szakács, A, Pécskay, Z, Panaiotu, C, Panaiotu, CE & Nedelcu, L 2004, 'Extension-related Miocene calc-alkaline magmatism in the Apuseni Mountains, Romania: Origin of magmas', Schweizerische Mineralogische und Petrographische Mitteilungen, vol. 84, no. 1-2, pp. 153-172.
Roşu, Emilian ; Seghedi, Ioan ; Downes, Hilary ; Alderton, David H M ; Szakács, Alexandru ; Pécskay, Z. ; Panaiotu, Cristian ; Panaiotu, Cristina Emilia ; Nedelcu, Liviu. / Extension-related Miocene calc-alkaline magmatism in the Apuseni Mountains, Romania : Origin of magmas. In: Schweizerische Mineralogische und Petrographische Mitteilungen. 2004 ; Vol. 84, No. 1-2. pp. 153-172.
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