Structural map of Variscan northern Sardinia (Italy)

Casini, Leonardo; Cuccuru, Stefano; Maino, M.; Oggiano, Giacomo; Puccini, Antonio; Rossi, P.

doi:10.1080/17445647.2014.936914

Cited by 28 publications

(35 citation statements)

References 39 publications

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“…The magmatic activity lasted between 340 and 285 Ma (Cocherie, Rossi, Fanning, & Guerrot, 2005;Paquette, Ménot, Pin, & Orsini, 2003). 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 Gaggero, Oggiano, Buzzi, Slejko, & Cortesogno, 2007;Paquette et al, 2003). Despite the recent improvement of geochronological and geochemical data, the knowledge of the Sardinia portion of the batholith is still far from complete, as large areas, they lack detailed geological and structural field mapping.…”

Section: Introductionmentioning

confidence: 99%

Structural and metallogenic map of late Variscan Arbus Pluton (SW Sardinia, Italy)

et al. 2015

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This 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. ARTICLE HISTORY

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Section: Introductionmentioning

confidence: 99%

Structural and metallogenic map of late Variscan Arbus Pluton (SW Sardinia, Italy)

et al. 2015

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“…In fact, the quartzites and amphibolites of the metamorphic basement are characterized by the lowest uranium concentrations (<2 µg/g) and were mainly investigated with HPGe measurements because they are badly exposed and poorly suited to in situ measurements. In contrast, the highest values in Figure 4 are found in the U-rich monzogranites (∼9 µg/g) of the La Maddalena pluton (Casini, Cuccuru, Maino, et al, 2015), investigated mostly with in situ studies.…”

Section: Mapping Radiometric Datamentioning

confidence: 81%

“…We suggest that the distribution of eU content is related to the Post-Variscan brittle structure, reported in Casini, Cuccuru, Maino, et al (2015), that affects the metamorphic units and the plutons of the VBNS. In particular, in the Tempio Pausania pluton (southwest of the study area), the major NE-SW faults correspond to anomalies in eU distribution and mark an area with higher eU content (5-7 µg/g) compared to the adjacent sectors of the pluton with lower eU content (∼3.5 µg/g).…”

Section: Discussionmentioning

confidence: 99%

“…The studies were planned based on the Geological map of Sardinia at a scale of 1:200,000 (Barca et al, 1996) and the structural map of Variscan Northern Sardinia at a scale of 1:100,000 (Casini, Cuccuru, Maino, et al, 2015).…”

Section: Methodsmentioning

confidence: 99%

“…Three main magmatic suites can be recognized: a magnesium-potassium complex exposed only in northern Corsica, a peraluminous calc-alkaline complex (Casini et al, 2012;Rossi & Cocherie, 1991) and finally, a late to postorogenic alkaline suite in the VBNS (Bonin, 2007). The 2100 km 2 of the VBNS (Figure 1) are characterized by several calc-alkaline plutons and a few minor alkaline complexes emplaced within migmatites and amphibolite-facies of metamorphic rocks (Casini, Cuccuru, Maino, et al, 2015). According to Cruciani, Franceschelli, Massonne, Carosi, and Montomoli (2013), the migmatites outcropping in the study area are related to high-pressure metamorphism that occurred in the Internal Nappes of the Sardinia Variscides at the age of the initial continent-continent collision.…”

Section: Geological Settingmentioning

confidence: 99%

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Uranium distribution in the Variscan Basement of Northeastern Sardinia

Xhixha¹,

Albéri

Baldoncini

et al. 2015

Journal of Maps

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We present a detailed map of uranium distribution and its uncertainties in the Variscan Basement of Northeastern Sardinia (VBNS) at a scale of 1:100,000. An area of 2100 km 2 was investigated by means of 535 data points obtained from laboratory and in situ gamma-ray spectrometry measurements. These data volume corresponds to the highest sampling density of the European Variscides, aimed at studying the genetic processes of the upper crust potentially triggered by an enrichment of radiogenic heat-producing elements. For the first time, the Kriging with Variance of Measurement Error method was used to assign weights to the input data which are based on the degree of confidence associated with the measurements obtained using different gamma-ray spectrometry techniques. A detailed tuning of the model parameters for the adopted Experimental Semi-Variogram led to the identification of a maximum distance of spatial variability coherent to the observed tendency of the experimental data. We demonstrate that the obtained uranium distribution in the VBNS, characterized by several calc-alkaline plutons emplaced within migmatitic massifs and amphibolite-facies metamorphic rocks, is an excellent benchmark for the study of 'hot' collisional chains. The uranium map of VBNS, and in particular the Arzachena minor pluton, confirms the emplacement model based on the recognition of the different petrological associations characterizing the Variscan magmatic processes in the Late Paleozoic. Furthermore, the presented model of the uranium content of the geological bedrock is a potential baseline for future mapping of radon-prone areas.ARTICLE HISTORY

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Syntectonic magmatism and reactivation of collisional structures during late-Variscan shearing (SW Sardinia, Italy)

Secchi

Casini

Cifelli

et al. 2022

Int J Earth Sci (Geol Rundsch)

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The Arbus igneous complex (SW Sardinia, Italy) represents a good example of a short time lived post-collisional composite pluton emplaced at shallow crustal level in the external zone of the Variscan chain. The pluton almost consists of granodiorite and leucogranite rock-suites emplaced at 304 ± 1 Ma within a main NW trending thrust separating the metamorphic wedge from the fold and thrust belt foreland. The pluton emplaced into a dilatational step over connecting two NW–SE dextral shear zones which belongs to a regional network of post-collisional strike-slip structures marking the transition from collision to post-collisional extension. The microstructure observed for quartz and K-feldspar confirms the lack of significant post-emplacement deformation, indicating only limited high-temperature sub-solidus recrystallization. Anisotropy of magnetic susceptivity data and field-structural analysis have been carried out to reconstruct the geometry of the pluton and the trajectories of magmatic flow in relation to regional deformation structures. Overall, the magmatic and the magnetic fabrics are broadly discordant with the metamorphic foliation of the country rocks, defining an EW trending elliptical asymmetric sill rooted in the SW quadrant. The reconstructed architecture combined to petrologic observation indicates that accretion of the pluton involved injection of multiple dykes through a sub-vertical feeder zone, combined to lateral flow of the roof controlled by inherited collisional structure. The duration of magmatic activity and the cooling history of the contact metamorphic aureole have been evaluated through a suite of 2D thermal models. All these observations, together with the available geochronological constraints are suggestive of very rapid construction of the pluton. The proposed emplacement model is fully consistent with the regional phase of strike-slip tectonics and widespread magmatism accommodating the large rotation of the Corsica-Sardinia block during the Carboniferous-Permian transition.

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Structural map of Variscan northern Sardinia (Italy)

Cited by 28 publications

References 39 publications

Structural and metallogenic map of late Variscan Arbus Pluton (SW Sardinia, Italy)

Structural and metallogenic map of late Variscan Arbus Pluton (SW Sardinia, Italy)

Uranium distribution in the Variscan Basement of Northeastern Sardinia

Syntectonic magmatism and reactivation of collisional structures during late-Variscan shearing (SW Sardinia, Italy)

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