Abstract

The growing recognition that many passive margins have experienced periods of post-rift uplift has raised new questions about the nature of the tectonic processes that drive such uplift. The eastern North America margin is of particular interest because it is a classic Atlantic-style margin that has long been suspected of tectonic rejuvenation, yet the timing of post-rift uplift events remains elusive. To address this question we present apatite U-Th/He and fission track ages from a 1300 m vertical transect in the White Mountains of New Hampshire (USA), including a 910-m-deep bore hole. Thermal modeling suggests a period of accelerated denudation from ca. 85 to 65 Ma. This timing is broadly similar to the timing of accelerated exhumation and compression on passive margins elsewhere in the Atlantic, raising the question of whether a common mechanism, such as a change in lateral stresses, changes in mantle convection, or climate change, could be responsible.

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