Measurements of the evolution of the Earth's ancient magnetic field may help constrain when the field first originated, when rapid convection began in the outer core, and the time of origin of the inner core. These events in turn may have had critical implications for the evolution the planetary interior, atmosphere, and life. However, little is known about the early history of the Earth's magnetic field due to the general absence of unaltered, ancient materials. However, the investigator's preliminary work suggests that part of the Shaw Batholith and other rocks in the Pilbara craton, Western Australia likely retain magnetic records dating back to their formation from 2.2-3.5 billion years ago. These rocks may therefore contain some of the oldest known paleomagnetic records on Earth. This grant will help determine the age and nature of the magnetization in the northernmost portion of the Shaw Batholith and to establish whether it retains records of the oldest geomagnetic reversals, and (2) begin to assess the fidelity of the geomagnetic, magnetostratigraphic, and environmental magnetic records in surface and drill core samples from other areas of the Pilbara. --
