Source of Dresser Formation 3.5 Ga dating
From Australian Government- Geoscience AustraliaAustralian Stratigraphic Units Database: 

Panorama Formation:  Paleoarchean min age: 3427 MA Age method: isotopic, U/Pb-Pb/Pb ion probe

Dresser Formation: Min Age: Ma: 3477 Age method: inferred, overlying unit

McPhee Formation:  Min Age: 3477 Age method: isotopic, U/Pb-Pb/Pb ion probe