The International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-four month research fellowship by Dr. Eric Tohver to work with Dr. Wilson Teixeira at the University of Sao Paulo in Sao Paulo, Brazil.
This fellow will undertake a paleomagnetic and geochronological study of the late Precambrian sediments of the western Amazon craton in the western Brazilian states of Mato Grosso and Mato Grosso do Sul. These sediments record the opening of the Iapetus Ocean between ancestral North America and the Amazon craton during the break-up of the Rodinia supercontinent. Glacial sediments found in this rift sequence have been ascribed to a snowball Earth episode, a period of extreme climatic conditions linked to the break-up of Rodinia. Radiogenic dating using the 40 Ar/39Ar technique will be carried out on primary, authigenic minerals from these sediments in order to determine the timing of rifting as well as the age of the glacial event. These geochronological results will be used in conjunction with paleomagnetic data to establish the paleogeographic context of the glacial deposits. In addition, these data will be compared with those from North America to document the opening of the Iapetus Ocean. This project will establish the tectonic link between North and South America Precambrian times. These sediments present a unique opportunity to help resolve the ongoing debate regarding extreme climates proposed for end Precambrian times.
The host, Dr. Teixeira is a leading expert in the Precambrian geology of South America and has recently established a new laboratory with laser extraction lines to complement the existing paleomagnetic laboratory, which utilized a field-free room and a 2G cryogenic magnetometer.
