Geological map of the Mount Avic massif (Western Alps Ophiolites)

Abstract

The Mount Avic massif consists of serpentinized peridotite exposed in the southern Aosta valley (Northwestern Alps), covering an area of ca. 180 km². The 1:10,000 scale geological map is located in the southern portion of the massif, where serpentinite is in contact with ophiolitic rocks pertaining to the Piemonte Zone, which represents the fossil Mesozoic Tethyan ocean. Southwards, ophiolites are overthrusted by the continental-derived Austroalpine Mont Glacier unit. Serpentinite consists of antigorite, magnetite, and coarse grained Ti-clinohumite, olivine, and diopside, which are reminiscent of the original mantle texture. Rodingitic mafic dykes are intruded within serpentinite; other mafic rocks, consisting of (not rodingitized) metagabbro and metabasalt with relict eclogitic minerals, occur as tectonic slices associated with serpentinite, calcschist and sulphide-rich epidosite. The map gives detailed and updated information on the structure and lithostratigraphy of the Mount Avic ophiolites, providing an insight to the mantle-crust transition of the Tethyan oceanic lithosphere.

Keywords:

• geological map
• Mount Avic
• Western Alps
• ophiolite
• Aosta Valley
• serpentinite

Acknowledgments

Funding for this research was provided by P.U.R. grants from the ‘Università degli Studi di Milano’ and grants from ‘Dote ricerca: FSE, Regione Lombardia’. The authors are grateful to Ente Parco Naturale del Mont Avic for logistic supports. We thank John Abraham, Gisella Rebay, and Laura Federico for their valuable comments, which helped to considerably improve the quality of the manuscript.