Combined apatite fission track and (U-Th)/He thermochronometry in a slowly cooled terrane: Results from a 3440-m-deep drill hole in the southern Canadian Shield

Abstract

Combined apatite fission track (AFT) and (U-Th)/He (AHe) thermochronometry can be particularly valuable for deciphering the low temperature thermal history of slowly cooled terranes, especially in those parts where Phanerozoic structural or stratigraphic geological history constraints are absent. We evaluate the results of such a combined approach through the study of 19 samples from a range of lithologies (e.g., granophyre, quartz gabbro, norite) over different depths in a 3440-m-deep drill hole in the 1.85 Ga Sudbury Igneous Complex (SIC), southern Canadian Shield. AFT ages range from ∼360 Ma at the surface to ∼140 Ma at the base of the well, with the age-depth profile following a sinuous ..