The Antrona Nappe is an Upper Penninic tectonic unit made up of oceanic rocks with eclogitic relics (similar to the Zermatt-Saas Fee Nappe, except for the metacherts that are missing). Structurally, it is situated below the Monte Rosa Nappe, but above the Siviez-Mischabel Nappe and its probable extension in the Camughera Nappe. This peculiar position between two Middle Penninic units raises questions concerning its kinematic history and paleogeographic origin.

The Mesozoic-aged Antrona Ophiolites separate the Monte Rosa Nappe (SE) from the overlying Portjengrat Unit (NW ; St.Bernard Nappe). They were affected by high-pressure metamorphism.