Abstract
ABSTRACTThis paper presents the geological, structural and metallogenic map of the Arbus Pluton, a late Variscan composite intrusion belonging to the Corsica-Sardinia Batholith. The pluton is surrounded and crosscut by a wide variety of vein ore deposits. The Arbus Pluton was emplaced at shallow crustal levels at the end of the Variscan Orogeny, along an E–W trending shear zone located in the low-grade external nappe pile of the Sardinian basement. The architecture of the pluton is roughly concentric with a core of cordierite-bearing leucogranites and an outer shell composed of pyroxene-bearing and hornblende granodiorites. New U/Pb dating on zircons of granodiorite yields an emplacement age of 303.7 ± 1.1 which improves previous Rb/Sr and Ar/Ar dating. The map has been compiled on the basis of new geological/structural surveys and petrographical studies coupled with in situ gamma ray spectrometry. All the data-sets have been processed using a geographical information system.
Highlights
The Paleozoic basement of Sardinia (Figure 1) is part of the Southern Variscan Belt (Rossi, Oggiano, & Cocherie, 2009)
According to Cocherie et al (2005), building the batholith involved three main episodes corresponding to three different magmatic suites: (i) the oldest Mg-K suite (U1) formed between 340 and 336 Ma, (ii) the calcalkaline suite (U2) between 320 and 290 Ma (Casini, Cuccuru, Maino, et al, 2015; Casini, Cuccuru, Maino, Oggiano, & Tiepolo, 2012) and (iii) a late-Variscan composite suite (U3) including alkaline and layered tholeitic bodies mostly emplaced around 285 Ma (Casini et al, 2015; Gaggero, Oggiano, Buzzi, Slejko, & Cortesogno, 2007; Paquette et al, 2003)
Past studies (Secchi, Brotzu, & Callegari, 1991) evidenced a mafic to felsic evolution dominated by crystal/liquid fractionation, in contrast with the processes documented for most igneous sequences of northern Sardinia (Bralia et al, 1981; Poli, Ghezzo, & Conticelli, 1989; Zorpi, Coulon, & Orsini, 1991)
Summary
The Paleozoic basement of Sardinia (Figure 1) is part of the Southern Variscan Belt (Rossi, Oggiano, & Cocherie, 2009). According to Cocherie et al (2005), building the batholith involved three main episodes corresponding to three different magmatic suites: (i) the oldest Mg-K suite (U1) formed between 340 and 336 Ma, (ii) the calcalkaline suite (U2) between 320 and 290 Ma (Casini, Cuccuru, Maino, et al, 2015; Casini, Cuccuru, Maino, Oggiano, & Tiepolo, 2012) and (iii) a late-Variscan composite suite (U3) including alkaline and layered tholeitic bodies mostly emplaced around 285 Ma (Casini et al, 2015; Gaggero, Oggiano, Buzzi, Slejko, & Cortesogno, 2007; Paquette et al, 2003). The Arbus Pluton is associated with a large hydrothermal vein network (Montevecchio–Ingurtosu–Gennamari district), already described in detailed but outdated papers (Cavinato & Zuffardi, 1948; Dessau, 1935, 1936; Zuffardi, 1958)
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