Tectonics, ore bodies, and gamma-ray logging of the Variscan basement, southern Gennargentu massif (central Sardinia, Italy)

Abstract

We present a structural geological map (1:14,000 scale) that covers a 100 km2 area of Variscan basement rocks exposed in central Sardinia. The mapped area is located between 39°56′20′′ N 9°04′59′′ E (northwestern corner) and 39°51′47′′ N 9°13′16′′ E (southeastern corner) on the southern slope of the Gennargentu massif, surrounding the mining village of Gadoni. This village was the hub of a mining district in central Sardinia. The region extends between the external and inner nappe zones of the Variscan orogenic wedge of Sardinia. Despite significant mining, the area lacked an up-to-date structural and stratigraphic synthesis comparable to that achieved in the southern Sardinia. This gap in knowledge was due to: (i) more complex structural deformation; (ii) slightly higher grade regional metamorphism including a late Variscan high-temperature overprint; (iii) difficulty in distinguishing terrigenous stratigraphic units that belong to different tectonic units; and (iv) the absence of key stratigraphic marker for resolve complex structures in the uppermost tectonic unit. Integration of field mapping, structural analysis, portable gamma-ray spectroscopy, and zircon U-Pb ages of intrusive rocks has enabled a new geological map and cross-sections. These contributions synthesize the collisional and postcollisional evolution of the region and its relationship with ore genesis.

Keywords

• Variscan chain
• structural map
• gamma-ray spectroscopy
• skarn
• Sardinia