The Bregaglia Intrusion forms a large plutonic body between the Val Bregaglia in the north and the Tonale Fault in the south; it extends with a narrow tail of about 40 km westward along the Tonale Fault (Insubric Fault). It comprises mainly calc-alkaline tonalite and granodiorite, derived from a primitive mantle melt and channeled from the base of the continental crust into the Periadriatic Fault System. The base of the pluton overlying the Gruf Complex shows evidence of synmagmatic folding and thrusting indicating contemporaneous late stage N–S shortening. Crystallization and emplacement of the Bregaglia Intrusion took place between 32 and 28 Ma. A smaller body related to the Bregaglia Intrusion crops out northwest of Sondrio (Triangia Pluton), where it intrudes the subvertical Tonale Nappe and its contact with the adjacent root zone of the Campo Nappe Complex.