New Fission Track Constrains on the Uplift and Erosion History of SE Brazil

New fission track data on apatites from 28 samples collected along 2 profiles across the onshore continental margin of SE Brazil are discussed. The fission track ages range from 60 to 180 Ma. with the younger ages generally occurring near the coast, and the older ages in the higher elevation regions inland. The mean track length range from 12-14.5 p.m and show a positive correlation with the elevation. The distribution of ages and mean track lengths are interpreted in terms of differential erosion, with an estimated >3.5 km of erosion for the coastal region and <500 m from above the escarpment. Isostatic considerations suggest that the present day elevation of the escarpment has a component of uplift related to differential erosion and associated rebound.