The emplacement age of the Muntele Mare Variscan granite (Apuseni Mountains, Romania)

Abstract

Like the Alps and Western Carpathians, the Apuseni Mountains represent a fragment of the Variscan orogen involved in the Alpine crustal shortenings. Thus the more extensive Alpine tectonic unit in the Apuseni Mountains, the Bihor Autochthonous Unit is overlain by several nappe systems. During the Variscan orogeny, the Bihor Unit was a part of the Some terrane involved as the upper plate in subduction, continental collision and finally in the orogen collapse and exhumation. The Variscan thermotectonic events were marked in the future Bihor Unit by the large Muntele Mare granitoid intrusion, an S-type anatectic body. Zircon U-Pb laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) dating yielded a weighted mean age of 290.9 ± 3.0 Ma and a concordia age of 291.1 ± 1.1 Ma. U-Pb isotope dilution zircon analyses yielded a lower intercept crystallization age of 296.6 + 5.7/-6.2 Ma. These two ages coincide in the error limits. Thus, the Muntele Mare granitoid pluton is a sign of the last stage in the Variscan history of the Apuseni Mountains. Many zircon grains show inheritance and/or Pb loss, typical for anatectic granitoid, overprinted by later thermotectonic events.

Sedimentary deposition of Bozeş Formation (Apuseni Mts., Romania) - detrital zircon dating and micropaleontological ages

“…As a result of a more detailed study on foraminifera assemblages performed along the valley, Dimian and Popa-Dimian (1964) assigned a Late Santonian -Campanian age for the sediments, the base of the section being represented by the upstream deposits, while downwards they become stratigraphically younger. The same authors also described an ammonite fauna, including P. colligatus Balintoni et al, 2009) Lupu et al, 1967).…”

Constraints on the depositional age and tectonometamorphic evolution of marbles from the Biharia Nappe System (Apuseni Mountains, Romania)

“…The presence of several different types of twinning in the thin sections allows us to infer a polyphase deformation of the Sohodol Marbles with the last stage at low temperatures, less than 200°C (Passchier & Trouw 1996;Ferrill et al 2004). The presence of Late Cretaceous post-tectonic sediments (Schuller 2004;Schuller et al 2009) overlying the marbles indicate thermal conditions for the Sohodol Marbles of ≤ 200°CduringLateCretaceoustimes.…”

From nappe stacking to exhumation: Cretaceous tectonics in the Apuseni Mountains (Romania)

“…1999; Balintoni et al. 2009, 2010). Following the pre-Mesozoic tectonics, the units experienced polyphase nappe stacking, metamorphic overprinting, and deformation during Alpine orogeny (Balintoni 1994; Dallmeyer et al.…”

“…1981; Hârtopanu and Hârtopanu 1986; Balintoni et al. 2009). On the west side of the Bihor gneiss–granite basement, a non-metamorphosed Permian–Early Cretaceous sedimentary sequence unconformably overlies these basement rocks (Fig.…”