Abstract
ABSTRACT This paper deals with the geological mapping of the late-Variscan Sàrrabus pluton, (south-eastern Sardinia), a shallow multiple and composite igneous complex dominated by several generations of granodiorites, metaluminous and peraluminous granites and repeated pulses of mantle-derived mafic magmas. The map has been compiled based on geological surveys at 1:10,000 and 1:5,000 scales, assisted by in situ gamma-ray spectrometry and detailed petrographic investigations. Granite-related ore deposits have been also reported. The emplacement age of the pluton can be constrained by U/Pb dating on zircons of Cala Regina granodiorite, yielding an age of 286 ± 9 Ma. The resulting scenario documents a bimodal magmatism controlled by an EW trending shear zone, followed by the shallower emplacement of several pulses of independent granite magmas.
Highlights
The Sardinia-Corsica block is a segment of the Southern Variscan Belt (Carmignani et al, 1994; Rossi et al, 2009), resulting from the early Carboniferous collision between Laurussia and Gondwana (Matte, 1986)
The more radiogenic nature of the granodioritic/monzogranitic Monte Nai Unit allows to discriminate it with respect to the granodioritic Cala Regina and Monte Cresia Units, while the peraluminous satellite intrusions of the Monte Maria Unit emerge as higher radiogenic spots within the southern low radiogenic part of the pluton
The whole data set is consistent with fast growth of the pluton during the granodioritic stage (i.e. Monte Cresia, Monte Nai and Cala Regina Units)
Summary
The Sardinia-Corsica block is a segment of the Southern Variscan Belt (Carmignani et al, 1994; Rossi et al, 2009), resulting from the early Carboniferous collision between Laurussia and Gondwana (Matte, 1986). This paper deals with the Sàrrabus igneous massif, which is a wide (400 km2) multiple and composite pluton located in south-easternmost part of the batholith It shows a complex architecture, including uncommon suites (i.e. hastingsite granites) and, compared to other massifs at the scale of the Variscan belt, a large incidence of mafic dikes. A wide network of fluorite-barite and Pb–Ag sulfide hydrothermal veins, mostly hosted in the metamorphic basement close to the contact with the intrusives is spatially and genetically associated with the Sàrrabus pluton Within this scenario, the geological map represents a mandatory basic tool for disclosing the tectono-magmatic history of the massif. The geological map represents a mandatory basic tool for disclosing the tectono-magmatic history of the massif In this regard, some unsolved issues mainly concern the discrimination within different intrusive units of similar composition and internal petrographic and structural features. The geostatistical processing of more than 100 in situ measurements better allowed the distinction among units and was useful in the reconstruction of the architecture of the Sàrrabus igneous massif, providing a geological-structural map at 1:50,000 full scale realized with a multi-methodological approach
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