Laser step–heating <sup>40</sup>Ar/<sup>39</sup>Ar analyses of biotites from meta–granites in the UHP Brossasco–Isasca Unit of Dora–Maira Massif, Italy

Two undeformed metagranite samples were collected from the UHP Brossasco–Isasca Unit (BIU) of Dora–Maira Massif, Italy to carry out the laser step–heating 40Ar/39Ar analyses of individual biotite crystals. The metagranites occur as undeformed domains (m– to ten of meters in size) within strongly deformed augen–gneiss. They still preserve their medium– to coarse– grained igneous texture and are composed mainly of K–feldspar, plagioclase...