EGU23-15137
https://doi.org/10.5194/egusphere-egu23-15137
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

An integrated structural and AMS study to define the emplacement of the Arbus pluton (SW Sardinia, Italy)

Francesca Cifelli1, Francesco Secchi2,3, Leonardo Casini2, Stefano Naitza4,3, Enrico Carta2, and Giacomo Oggiano2
Francesca Cifelli et al.
  • 1Università degli Studi Roma Tre, Dipartimento di Scienze, Rome, Italy (francesca.cifelli@uniroma3.it)
  • 2Dipartimento di Scienze Chimiche, Fisiche, Matematiche e Naturali, Università Degli Studi di Sassari, Sassari, Italy
  • 3CNR IGAG Roma Sapienza
  • 4Dipartimento Scienze Chimiche e Geologiche. Università Degli Studi di Cagliari, Cagliari, Italy

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 col- lision 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.

How to cite: Cifelli, F., Secchi, F., Casini, L., Naitza, S., Carta, E., and Oggiano, G.: An integrated structural and AMS study to define the emplacement of the Arbus pluton (SW Sardinia, Italy), EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15137, https://doi.org/10.5194/egusphere-egu23-15137, 2023.