Technical note: Incorporating topographic deflection effects into thermal history modelling

Abstract

This contribution describes a set of equations and relations to calculate accurate cooling paths through the 2D temperature field of an exhuming region with periodic topography. A 1D model adequately captures the time-varying component of the system regardless of the complexity of the cooling path, making the computation efficient. A series of 2D finite element models demonstrate how temperatures below the periodic mid-slope, or mean topography, can be mapped to those below ridges and valleys, and how these transitions vary with topographic period and amplitude and the ratio of the near-surface geotherm to the atmospheric lapse rate. These new calculations are implemented into HeFTy to support simultaneous modelling of samples collected along topographic profiles, particularly for terranes with long-lived topography that exhumed through an inflected temperature field. Users should bear in mind the limitations of this simplified approach, notably that it presumes a single dominant topographic wavelength, and that it does not encompass other advective processes such as faulting.